WorldWideScience

Sample records for aperture radar imagery

  1. Interferometric synthetic aperture radar imagery of the Gulf Stream

    Science.gov (United States)

    Ainsworth, T. L.; Cannella, M. E.; Jansen, R. W.; Chubb, S. R.; Carande, R. E.; Foley, E. W.; Goldstein, R. M.; Valenzuela, G. R.

    1993-01-01

    The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.

  2. Stellwagen Bank National Marine Sanctuary - Synthetic Aperture Radar (SAR) Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geodatabase contains Synthetic Aperture Radar images (SAR), which consist of a fine resolution (12.5-50m), two-dimensional radar backscatter map of the...

  3. Water Level Detection Using Synthetic Aperture Radar Imagery

    International Nuclear Information System (INIS)

    Reservoir water levels are of interest for international safeguards and domestic monitoring because they can be used as indicators of processing activity, uranium mine tailings protection status, or power generation for clandestine operation. Monitoring of water levels using satellite technology, especially civilian synthetic aperture radar (SAR) for remote or restricted-access sites worldwide has the potential to be a valuable tool for national/international safeguards as well as environmental monitoring applications. Unlike optical sensors, SAR is capable of reliable repeat monitoring regardless of cloud cover or solar illumination, i.e. it can image the target through clouds and darkness. Because of this ability, quick turn around for a SAR image is almost always guaranteed. SAR is very sensitive to the land/water interface and can be used to extract detailed elevation models. SAR is also sensitive to metallic structures or objects and can thus be useful in detection of heavy equipment or undeclared construction at decommissioned facilities. Although spaceborne SAR cannot match the resolution of optical satellites, future SAR satellites will offer much better resolution (e.g., approximately 3 metres for RADARSAT-2). Furthermore, future SAR satellites will offer different polarization and frequency channels to provide terrain and vegetation classification. The objective is to investigate the use of SAR for water level detection using Canada's RADARSAT-1 imagery. Three Canadian sites were chosen for our study: Niagara Area Hydro Reservoir; Quirke Lake uranium tailings management facility (TMF); and JEB Pit TMF. Initial results, using RADARSAT-1 data acquired over a three year period, show dramatic changes in both the total water surface area and markers (natural or man-made) becoming visible as the water level decreases. These very promising results indicated that SAR imagery can be used as an excellent tool for mapping remote location (which is useful for

  4. Potential applications of synthetic aperture radar (SAR) satellite imagery to nuclear safeguards

    International Nuclear Information System (INIS)

    Particular strengths of synthetic aperture radar (SAR) satellite imagery are highlighted and potential applications of this unique all-weather, day/night information source to safeguards are described and illustrated by examples. The potential applications can be discussed in three categories: infrastructure analysis, surface change detection, and subsidence mapping. Examples are drawn from the literature and from experiments carried out under the Canadian Safeguards Support Program on proxy sites. Many new unclassified high resolution SAR satellites will soon be launched, and their impact on the state-of-the-art in satellite imaging for safeguards is estimated. We conclude that radar imagery can provide day/night all-weather information that is complementary to high resolution optical imagery. We further conclude that radar imagery can provide some unique information that is difficult to obtain in any other way. (author)

  5. A Supervised Classification Method for Levee Slide Detection Using Complex Synthetic Aperture Radar Imagery

    Directory of Open Access Journals (Sweden)

    Ramakalavathi Marapareddy

    2016-09-01

    Full Text Available The dynamics of surface and sub-surface water events can lead to slope instability, resulting in anomalies such as slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We have implemented a supervised Mahalanobis distance classification algorithm for the detection of slough slides on levees using complex polarimetric Synthetic Aperture Radar (polSAR data. The classifier output was followed by a spatial majority filter post-processing step that improved the accuracy. The effectiveness of the algorithm is demonstrated using fully quad-polarimetric L-band Synthetic Aperture Radar (SAR imagery from the NASA Jet Propulsion Laboratory’s (JPL’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR. The study area is a section of the lower Mississippi River valley in the southern USA. Slide detection accuracy of up to 98 percent was achieved, although the number of available slides examples was small.

  6. Volcanology: Lessons learned from Synthetic Aperture Radar imagery

    Science.gov (United States)

    Pinel, Virginie; Poland, Michael P.; Hooper, Andy

    2014-01-01

    Twenty years of continuous Earth observation by satellite SAR have resulted in numerous new insights into active volcanism, including a better understanding of subsurface magma storage and transport, deposition of volcanic materials on the surface, and the structure and development of volcanic edifices. This massive archive of data has resulted in fundamental leaps in our understanding of how volcanoes work – for example, identifying magma accumulation at supposedly quiescent volcanoes, even in remote areas or in the absence of ground-based data. In addition, global compilations of volcanic activity facilitate comparison of deformation behavior between different volcanic arcs and statistical evaluation of the strong link between deformation and eruption. SAR data are also increasingly used in timely hazard evaluation thanks to decreases in data latency and growth in processing and analysis techniques. The existing archive of SAR imagery is on the cusp of being enhanced by a new generation of satellite SAR missions, in addition to ground-based and airborne SAR systems, which will provide enhanced temporal and spatial resolution, broader geographic coverage, and improved availability of data to the scientific community. Now is therefore an opportune time to review the contributions of SAR imagery to volcano science, monitoring, and hazard mitigation, and to explore the future potential for SAR in volcanology. Provided that the ever-growing volume of SAR data can be managed effectively, we expect the future application of SAR data to expand from being a research tool for analyzing volcanic activity after the fact, to being a monitoring and research tool capable of imaging a wide variety of processes on different temporal and spatial scales as those processes are occurring. These data can then be used to develop new models of how volcanoes work and to improve quantitative forecasts of volcanic activity as a means of mitigating risk from future eruptions.

  7. Analyses of Multi-Year Synthetic Aperture Radar Imagery of Dry-Fallen Intertidal Flats

    Science.gov (United States)

    Gade, M.; Melchionna, S.; Kemme, L.

    2015-04-01

    We analyzed a great deal of high-resolution Synthetic Aperture Radar (SAR) data of dry-fallen intertidal flats in the German Wadden Sea with respect to the imaging of sediments, macrophytes, and mussels. TerraSAR-X and Radarsat-2 images of five test areas along the German North Sea coast acquired between 2008 and 2013 form the basis for the present investigation and are used to demonstrate that pairs of SAR images, if combined through basic algebraic operations, can already provide useful indicators for morphological changes and for bivalve (oyster and mussel) beds. Depending on the type of sediment, but also on the water level and on environmental conditions (wind speed) exposed sediments may show up on SAR imagery as areas of enhanced, or reduced, radar backscattering. The (multi-temporal) analysis of series of such images allows for the detection of mussel beds, and our results show evidence that also single-acquisition, multi-polarization SAR imagery can be used for that purpose.

  8. CLASSIFIER FUSION OF HIGH-RESOLUTION OPTICAL AND SYNTHETIC APERTURE RADAR (SAR SATELLITE IMAGERY FOR CLASSIFICATION IN URBAN AREA

    Directory of Open Access Journals (Sweden)

    T. Alipour Fard

    2014-10-01

    Full Text Available This study concerned with fusion of synthetic aperture radar and optical satellite imagery. Due to the difference in the underlying sensor technology, data from synthetic aperture radar (SAR and optical sensors refer to different properties of the observed scene and it is believed that when they are fused together, they complement each other to improve the performance of a particular application. In this paper, two category of features are generate and six classifier fusion operators implemented and evaluated. Implementation results show significant improvement in the classification accuracy.

  9. Potential applications of synthetic aperture radar (SAR) satellite imagery to nuclear safeguards

    International Nuclear Information System (INIS)

    Particular strengths and weaknesses of synthetic aperture radar (SAR) satellite imagery are highlighted and potential applications of this unique all-weather, day/night information source to safeguards are described and illustrated by examples. Examples are drawn from the literature and from experiments carried out under the Canadian Safeguards Support Program on proxy sites. Many new unclassified high resolution SAR satellites will soon be launched, and their impact on the state-of-the-art in satellite imaging for safeguards is estimated. Today, all unclassified SAR satellites in regular operation are C-band, using approximately 5.3 gigahertz centre frequency for radar pulse emissions. Resolution is limited to 9 metres. Within one year 3 m resolution C-band and 1 m resolution X-band (specifically 9.6 gigahertz) systems will be available. This divides our summary of applicable techniques into the concrete and proven (for low resolution C-band) and the intriguing but more speculative (for 1m X-band). The resolution of current C-band sensors such as RADARSAT-1 is insufficient to permit identification of any but the largest of structures (roads, dams, large ships, airstrips, bridges, large buildings). RADARSAT-2 will have significantly improved resolution (3m), but identification remains out of reach for many targets, and the identification possible with high resolution optical systems such as Quickbird or IKONOS cannot be matched. C-band SARs have a particular strength, however, when used in a monitoring mode where multiple observations over time can be combined using sophisticated comparative methods. Combining multitemporal observations using colour composites is a simple but effective method that has been used for many years with all types of imagery. SAR-specific techniques which rely upon the inherent radar phase measurements (so-called coherent, or interferometric techniques) are much more involved. When conditions are favourable these techniques can render

  10. Sea Ice Deformation State From Synthetic Aperture Radar Imagery - Part II: Effects of Spatial Resolution and Noise Level

    DEFF Research Database (Denmark)

    Dierking, Wolfgang; Dall, Jørgen

    2008-01-01

    C- and L-band airborne synthetic aperture radar (SAR) imagery acquired at like- and cross-polarization over sea ice under winter conditions is examined with the objective to study the discrimination between level ice and ice deformation features. High-resolution low-noise data were analysed....... The signal-to-noise ratio is varied between typical noise levels for airborne imagery and satellite data. Areal fraction of deformed ice and average deformation distance are determined for each image product. At L-band, the retrieved values of the areal fraction get larger as the image resolution is degraded...... ice. The retrieval of deformation parameters using simulated images that resemble ERS-2 SAR, Envisat ASAR and ALOS PALSAR data products is discussed. Basic differences between real and simulated ERS-2 SAR images are analyzed....

  11. A 2D wavenumber domain phase model for ground moving vehicles in synthetic aperture radar imagery

    International Nuclear Information System (INIS)

    In this paper, fundamental phase characteristics of moving vehicles in synthetic aperture radar (SAR) data are reviewed. A 2D phase model for a moving point scatterer is expressed in terms of range and azimuth wavenumbers. The moving point scatterer impulse response is then the 2D Fourier transform of the associated complex sinusoid. Numerical computation of the 2D phase for arbitrary relative radar-point scatter motion is organized as a composition of functions expressing time, frequency and angle in terms of wavenumber vectors. An analytic model for the phase is subsequently derived in the special case that the Doppler cone angle is 90°. With that model it is observed that the map from velocity and acceleration to quadratic phase is not one-to-one and therefore the associated inverse problem is ill-posed. An example of moving vehicle Doppler energy dispersion and corresponding phase measured in clutter suppressed SAR image data is provided. Clutter suppression is achieved by application of spacetime adaptive processing. (paper)

  12. Exploiting synthetic aperture radar imagery for retrieving vibration signatures of concealed machinery

    Science.gov (United States)

    Pérez, Francisco; Campbell, Justin B.; Jaramillo, Monica; Dunkel, Ralf; Atwood, Thomas; Doerry, Armin; Gerstle, Walter H.; Santhanam, Balu; Hayat, Majeed M.

    2016-05-01

    It has been demonstrated that the instantaneous acceleration associated with vibrating objects that are directly imaged by synthetic aperture radar (SAR) can be estimated through the application of the discrete fractional Fourier transform (DFrFT) using the information contained in the complex SAR image. In general, vibration signatures may include, for example, the number of chirped sinusoids as well as their respective base frequencies and chirp rates. By further processing the DFrFT-processed data for clutter-noise rejection by means of pseudo- subspace methods, has been shown that the SAR-vibrometry method can be reliable as long as the signal-to-noise ratio (SNR) and the signal-to-clutter ratio (SCR) of the slow-time SAR signal at the range-line of interest exceeds 15dB. Meanwhile, the Nyquist theorem dictates that the maximum measurable vibration frequency is limited by half of the pulse-repetition frequency. This paper focuses on the detection and estimation of vibrations generated by machinery concealed within buildings and other structures. This is a challenging task in general because the vibration signatures of the source are typically altered by their housing structure; moreover, the SNR at the surface of the housing structure tends to be reduced. Here, experimental results for three different vibrating targets, including one concealed target, are reported using complex SAR images acquired by the General Atomics Lynx radar at resolutions of 1-ft and 4-in. The concealed vibrating target is actuated by a gear motor with an off-balance weight attached to it, which is enclosed by a wooden housing. The vibrations of the motor are transmitted to a chimney that extends above the housing structure. Using the SAR vibrometry approach, it is shown that it is possible to distinguish among the three vibrating objects based upon their vibration signatures.

  13. Agricultural crop harvest progress monitoring by fully polarimetric synthetic aperture radar imagery

    Science.gov (United States)

    Yang, Hao; Zhao, Chunjiang; Yang, Guijun; Li, Zengyuan; Chen, Erxue; Yuan, Lin; Yang, Xiaodong; Xu, Xingang

    2015-01-01

    Dynamic mapping and monitoring of crop harvest on a large spatial scale will provide critical information for the formulation of optimal harvesting strategies. This study evaluates the feasibility of C-band polarimetric synthetic aperture radar (PolSAR) for monitoring the harvesting progress of oilseed rape (Brassica napus L.) fields. Five multitemporal, quad-pol Radarsat-2 images and one optical ZY-1 02C image were acquired over a farmland area in China during the 2013 growing season. Typical polarimetric signatures were obtained relying on polarimetric decomposition methods. Temporal evolutions of these signatures of harvested fields were compared with the ones of unharvested fields in the context of the entire growing cycle. Significant sensitivity was observed between the specific polarimetric parameters and the harvest status of oilseed rape fields. Based on this sensitivity, a new method that integrates two polarimetric features was devised to detect the harvest status of oilseed rape fields using a single image. The validation results are encouraging even for the harvested fields covered with high residues. This research demonstrates the capability of PolSAR remote sensing in crop harvest monitoring, which is a step toward more complex applications of PolSAR data in precision agriculture.

  14. Joint use of multiple Synthetic Aperture Radar imagery for the detection of bivalve beds and morphological changes on intertidal flats

    Science.gov (United States)

    Gade, Martin; Melchionna, Sabrina

    2016-03-01

    We analyzed a large amount of high-resolution Synthetic Aperture Radar (SAR) data of dry-fallen intertidal flats on the German North Sea coast with respect to the imaging of sediments, macrophytes, and mussels. TerraSAR-X and Radarsat-2 images of four test areas acquired from 2008 to 2013 form the basis for the present investigation and are used to demonstrate that pairs of SAR images, if combined through basic algebraic operations, can already provide indicators for morphological changes and for bivalve (oyster and mussel) beds. Multi-temporal analyses of series of SAR images allow detecting bivalve beds, since the radar backscattering from those beds is generally high, whereas that from sediments may vary with imaging geometry and environmental conditions. Our results further show evidence that also single-acquisition, dual-polarization SAR imagery can be used in this respect. The polarization coefficient (i.e., the ratio of the difference and the sum of both co-polarizations) can be used to infer indicators for oyster and blue-mussel beds.

  15. Synthetic Aperture Radar Interferometry

    Science.gov (United States)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  16. Inverse synthetic aperture radar imagery of a man with a rocket propelled grenade launcher

    Science.gov (United States)

    Tran, Chi N.; Innocenti, Roberto; Kirose, Getachew; Ranney, Kenneth I.; Smith, Gregory

    2004-08-01

    As the Army moves toward more lightly armored Future Combat System (FCS) vehicles, enemy personnel will present an increasing threat to U.S. soldiers. In particular, they face a very real threat from adversaries using shoulder-launched, rocket propelled grenade (RPG). The Army Research Laboratory has utilized its Aberdeen Proving Ground (APG) turntable facility to collect very high resolution, fully polarimetric Ka band radar data at low depression angles of a man holding an RPG. In this paper, we examine the resulting low resolution and high resolution range profiles; and based on the observed radar cross section (RCS) value, we attempt to determine the utility of Ka band radar for detecting enemy personnel carrying RPG launchers.

  17. Synthetic Aperture Radar - Hardware Development

    OpenAIRE

    Rosner, V.; Seller, R.; L. Dudas; Kazi, K.; Miko, G.

    2009-01-01

    Experimental real and synthetic aperture radar are developed from the base-band digital unit to the analogue RF parts, based on solid state units, using pulse compression for radar imaging. Proper QPSK code is found for matched filter.

  18. Applications of Radarsat-1 synthetic aperture radar imagery to assess hurricane-related flooding of coastal Louisiana

    Science.gov (United States)

    Kiage, L.M.; Walker, N.D.; Balasubramanian, S.; Babin, A.; Barras, J.

    2005-01-01

    The Louisiana coast is subjected to hurricane impacts including flooding of human settlements, river channels and coastal marshes, and salt water intrusion. Information on the extent of flooding is often required quickly for emergency relief, repairs of infrastructure, and production of flood risk maps. This study investigates the feasibility of using Radarsat-1 SAR imagery to detect flooded areas in coastal Louisiana after Hurricane Lili, October 2002. Arithmetic differencing and multi-temporal enhancement techniques were employed to detect flooding and to investigate relationships between backscatter and water level changes. Strong positive correlations (R2=0.7-0.94) were observed between water level and SAR backscatter within marsh areas proximate to Atchafalaya Bay. Although variations in elevation and vegetation type did influence and complicate the radar signature at individual sites, multi-date differences in backscatter largely reflected the patterns of flooding within large marsh areas. Preliminary analyses show that SAR imagery was not useful in mapping urban flooding in New Orleans after Hurricane Katrina's landfall on 29 August 2005. ?? 2005 Taylor & Francis.

  19. Digital exploitation of synthetic aperture radar

    Science.gov (United States)

    Wagner, H. L.; Shuchman, R. A.

    1977-01-01

    A digital processing and analysis scheme for use with digitized synthetic aperture radar data was developed. Using data from a four channel system, the imagery is preprocessed using specially designed software and then analyzed using preexisting facilities originally intended for use with MSS type data. Geometric and radiometric correction may be performed if desired, as well as classification analysis, Fast Fourier transform, filtering and level slice and display functions. The system provides low cost output in real time, permitting interactive imagery analysis. System information flow diagrams as well as sample output products are shown.

  20. Synthetic Aperture Radar - Hardware Development

    Directory of Open Access Journals (Sweden)

    V. Rosner

    2009-06-01

    Full Text Available Experimental real and synthetic aperture radar are developed from the base-band digital unit to the analogue RF parts, based on solid state units, using pulse compression for radar imaging. Proper QPSK code is found for matched filter.

  1. Application of Lipschitz Regularity and Multiscale Techniques for the Automatic Detection of Oil Spills in Synthetic Aperture Radar Imagery

    Science.gov (United States)

    Ajadi, O. A.; Meyer, F. J.; Tello, M.

    2015-12-01

    This research presents a promising new method for the detection and tracking of oil spills from Synthetic Aperture Radar (SAR) data. The method presented here combines a number of advanced image processing techniques in order to overcome some common performance limitations of SAR-based oil spill detection. Principal among these limitations are: (1) the radar cross section of the ocean surface strongly depends on wind and wave activities and is therefore highly variable; (2) the radar cross section of oil covered waters is often indistinguishable from other dark ocean features such as low wind areas or oil lookalikes, leading to ambiguities in oil spill detection. In this paper, we introduce two novel image analysis techniques to largely mitigate the aforementioned performance limitations, namely Lipschitz regularity (LR) and Wavelet transforms. We used LR, an image texture parameter akin to the slope of the local power spectrum, in our approach to mitigate these limitations. We show that the LR parameter is much less sensitive to variations of wind and waves than the original image amplitude, lending itself well for normalizing image content. Beyond its benefit for image normalization, we also show that the LR transform enhances the contrast between oil-covered and oil-free ocean surfaces and therefore improves overall spill detection performance. To calculate LR, the SAR images are decomposed using two-dimensional continuous wavelet transform (2D-CWT), which are furthermore transformed into Holder space to measure LR. Finally, we demonstrate that the implementation of wavelet transforms provide additional benefits related to the adaptive reduction of speckle noise. We show how LR and CWT are integrated into our image analysis workflow for application to oil spill detection. To describe the performance of this approach under controlled conditions, we applied our method to simulated SAR data of wind driven oceans containing oil spills of various properties. We also

  2. SETTLEMENT AREA MAPPING USING OPTICAL AND SYNTHETIC APERTURE RADAR (SAR) REMOTE SENSING IMAGERY TO SUPPORT TSUNAMI RISK ASSESSMENT

    Science.gov (United States)

    Khomarudin, R.; Strunz, G.; Ludwig, R.; Post, J.; Zosseder, K.; Esch, T.; Indrajit, A.; Khomarudin, R.

    2009-12-01

    In Indonesia more than 60% of the population and more than 80% of the industrial areas are located in the coastal regions. Many of the development activities take place in the coastal areas such as fisheries, agriculture, industry, transportation, tourism, urban development, that are particularly vulnerable to natural disasters. Indonesia is one of the most vulnerable countries on the world with respect to the tsunami threat. In the framework of the GITEWS (German Indonesian Tsunami Early Warning System) project a comprehensive risk assessment is being performed. To mitigate and decrease the loss of lives caused by tsunami, the information on people activities and settlement area is important. Remote sensing techniques can be applied to map settlement areas, which are used as input for tsunami risk assessment. This paper presents the results of the development and application of classification techniques for settlement extraction using Landsat TM and TerraSAR-X imagery. Several methods, like region growing, Index based built up index (IBI) and speckle divergence methods, have been investigated to extract settlement areas in the districts of Cilacap and Padang. The decision tree and neighborhood algorithm has also been used for performing the classification steps. The results of this research are promising, especially the SAR techniques based on TerraSAR-X gave highly accurate results with more than 85% overall accuracy and low omission and commission errors. Keyword: Remote Sensing, Settlement Mapping, Region Growing, Index Based Built-up Index, SAR Speckle Divergence

  3. Synthetic aperture radar: principles and applications

    International Nuclear Information System (INIS)

    In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information. (author)

  4. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  5. Synthetic Aperture Radar Missions Study Report

    Science.gov (United States)

    Bard, S.

    2000-01-01

    This report reviews the history of the LightSAR project and summarizes actions the agency can undertake to support industry-led efforts to develop an operational synthetic aperture radar (SAR) capability in the United States.

  6. Motion compensation of Synthetic Aperture Radar

    OpenAIRE

    Duncan, David; Long, David

    2003-01-01

    Synthetic aperture radar (SAR) is a digital signal processing technique which enhances the azimuth resolution of a radar image using the target doppler history created by the motion of the radar platform. If the platform deviates from a constant velocity, straight-line path then image quality is lost and image details become unfocused. Motion compensation (MOCO) is a technique in which the position and attitude of the platform is recorded or estimated and then used to correct the scene's dopp...

  7. RADARSAT-1 synthetic aperture radar analysis

    International Nuclear Information System (INIS)

    The M/V Selendang Ayu grounded off Unalaska Island in Alaska on December 8, 2004, and spilled over 1270 m3 of oil and an unknown quantity of soybeans. The freighter grounded nearshore in a high-wave energy zone along a remote and rugged coastline, a terrain which can cause difficulties for remote sensors in detecting oil slicks. In addition, guano, kelp beds, whale and fish sperm, and releases from fishing activities generated biogenic films on the sea surface that had a signature similar to that of petroleum films. RADARSAT-1 synthetic aperture radar (SAR) imagery was used as part of the response effort to assist in the pollution monitoring effort. This paper described the methodology and results of the RADARSAT-1 analysis. Detailed information on the spill response was reported daily, and provided an opportunity to compare field observations with RADARSAT-1 SAR imagery. Observers recorded observations onto electronic maps during 35 aerial surveillance flights. Fifty-seven incident reports describing the vessel status were also used for comparison. Using screening criteria for the favorable wind and wave conditions, 37 images were available for viewing the wreck, and 22 images were acceptable for oil slick viewing. Image analysis for the wreck suggested that the sensor has the resolution and capability to monitor a grounded freighter. Visual inspection of the images showed that SAR can capture changes in vessel status, such as the gradual sinking of the bow. However, SAR's oil slick detection capability was disappointing due to the significant number of biogenic films in the nearshore areas of Alaska. It was concluded that future work should concentrate on developing a ranking system to indicate analysis confidence that a particular image does in fact contain a petroleum pocket. 25 refs., 2 tabs., 10 figs

  8. RADARSAT-1 synthetic aperture radar analysis

    Energy Technology Data Exchange (ETDEWEB)

    Simecek-Beatty, D. [National Oceanic and Atmospheric Adminstration, National Ocean Service, Seattle, WA (United States). Office of Response and Restoration; Pichel, W.G. [National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information Service, Camp Springs, MD (United States). Office of Research and Applications

    2006-07-01

    The M/V Selendang Ayu grounded off Unalaska Island in Alaska on December 8, 2004, and spilled over 1270 m{sup 3} of oil and an unknown quantity of soybeans. The freighter grounded nearshore in a high-wave energy zone along a remote and rugged coastline, a terrain which can cause difficulties for remote sensors in detecting oil slicks. In addition, guano, kelp beds, whale and fish sperm, and releases from fishing activities generated biogenic films on the sea surface that had a signature similar to that of petroleum films. RADARSAT-1 synthetic aperture radar (SAR) imagery was used as part of the response effort to assist in the pollution monitoring effort. This paper described the methodology and results of the RADARSAT-1 analysis. Detailed information on the spill response was reported daily, and provided an opportunity to compare field observations with RADARSAT-1 SAR imagery. Observers recorded observations onto electronic maps during 35 aerial surveillance flights. Fifty-seven incident reports describing the vessel status were also used for comparison. Using screening criteria for the favorable wind and wave conditions, 37 images were available for viewing the wreck, and 22 images were acceptable for oil slick viewing. Image analysis for the wreck suggested that the sensor has the resolution and capability to monitor a grounded freighter. Visual inspection of the images showed that SAR can capture changes in vessel status, such as the gradual sinking of the bow. However, SAR's oil slick detection capability was disappointing due to the significant number of biogenic films in the nearshore areas of Alaska. It was concluded that future work should concentrate on developing a ranking system to indicate analysis confidence that a particular image does in fact contain a petroleum pocket. 25 refs., 2 tabs., 10 figs.

  9. Multibeam synthetic aperture radar for global oceanography

    Science.gov (United States)

    Jain, A.

    1979-01-01

    A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam iilluminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system.

  10. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  11. Simultaneous Navigation and Synthetic Aperture Radar Focusing

    OpenAIRE

    Sjanic, Zoran; Gustafsson, Fredrik

    2015-01-01

    Synthetic aperture radar (SAR) equipment is a radar imaging system that can be used to create high-resolution images of a scene by utilizing the movement of a flying platform. Knowledge of the platforms trajectory is essential to get good and focused images. An emerging application field is real-time SAR imaging using small and cheap platforms where estimation errors in navigation systems imply unfocused images. This contribution investigates a joint estimation of the trajectory and SAR image...

  12. Sparse synthetic aperture radar imaging with optimized azimuthal aperture

    Institute of Scientific and Technical Information of China (English)

    ZENG Cao; WANG MinHang; LIAO GuiSheng; ZHU ShengQi

    2012-01-01

    To counter the problem of acquiring and processing huge amounts of data for synthetic aperture radar (SAR) using traditional sampling techniques,a method for sparse SAR imaging with an optimized azimuthal aperture is presented.The equivalence of an azimuthal match filter and synthetic array beamforming is shown so that optimization of the azimuthal sparse aperture can be converted to optimization of synthetic array beamforming.The azimuthal sparse aperture,which is composed of a middle aperture and symmetrical bilateral apertures,can be obtained by optimization algorithms (density weighting and simulated annealing algorithms,respectively).Furthermore,sparse imaging of spectrum analysis SAR based on the optimized sparse aperture is achieved by padding zeros at null samplings and using a non-uniform Taylor window. Compared with traditional sampling,this method has the advantages of reducing the amount of sampling and alleviating the computational burden with acceptable image quality.Unlike periodic sparse sampling,the proposed method exhibits no image ghosts.The results obtained from airborne measurements demonstrate the effectiveness and superiority of the proposed method.

  13. Analytic inversion in synthetic aperture radar.

    OpenAIRE

    Rothaus, O. S.

    1994-01-01

    A method of processing synthetic aperture radar signals that avoids some of the approximations currently in use that appear to be responsible for severe phase distortions is described. As a practical matter, this method requires N3 numerical operations, as opposed to the N2 ln N currently the case, but N3 is now easily managed, for N in the range of interest.

  14. Convolutional neural networks for synthetic aperture radar classification

    Science.gov (United States)

    Profeta, Andrew; Rodriguez, Andres; Clouse, H. Scott

    2016-05-01

    For electro-optical object recognition, convolutional neural networks (CNNs) are the state-of-the-art. For large datasets, CNNs are able to learn meaningful features used for classification. However, their application to synthetic aperture radar (SAR) has been limited. In this work we experimented with various CNN architectures on the MSTAR SAR dataset. As the input to the CNN we used the magnitude and phase (2 channels) of the SAR imagery. We used the deep learning toolboxes CAFFE and Torch7. Our results show that we can achieve 93% accuracy on the MSTAR dataset using CNNs.

  15. Synthetic aperture radar and interferometry development at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-04-01

    Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic aperture radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. SAR complements photographic and other optical imaging capabilities because of the minimum constrains on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies. Interferometry is a method for generating a three-dimensional image of terrain. The height projection is obtained by acquiring two SAR images from two slightly differing locations. It is different from the common method of stereoscopic imaging for topography. The latter relies on differing geometric projections for triangulation to define the surface geometry whereas interferometry relies on differences in radar propagation times between the two SAR locations. This paper presents the capabilities of SAR, explains how SAR works, describes a few SAR applications, provides an overview of SAR development at Sandia, and briefly describes the motion compensation subsystem.

  16. Performance limits for Synthetic Aperture Radar.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-02-01

    The performance of a Synthetic Aperture Radar (SAR) system depends on a variety of factors, many which are interdependent in some manner. It is often difficult to ''get your arms around'' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics, no matter how bright the engineer tasked to generate a system design. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall SAR system. For example, there are definite optimum frequency bands that depend on weather conditions and range, and minimum radar PRF for a fixed real antenna aperture dimension is independent of frequency. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the ''seek time''.

  17. Signal based motion compensation for synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    John Kirk

    1999-06-07

    The purpose of the Signal Based Motion Compensation (SBMC) for Synthetic Aperture Radar (SAR) effort is to develop a method to measure and compensate for both down range and cross range motion of the radar in order to provide high quality focused SAR imagery in the absence of precision measurements of the platform motion. Currently SAR systems require very precise navigation sensors for motion compensation. These sensors are very expensive and are often supplied in pairs for reliability. In the case of GPS they can be jammed, further degrading performance. This makes for a potentially very expensive and possibly vulnerable SAR system. SBMC can eliminate or reduce the need for these expensive navigation sensors thus reducing the cost of budget minded SAR systems. The results on this program demonstrated the capability of the SBMC approach.

  18. Augmented reality using ultra-wideband radar imagery

    Science.gov (United States)

    Nguyen, Lam; Koenig, Francois; Sherbondy, Kelly

    2011-06-01

    The U.S. Army Research Laboratory (ARL) has been investigating the utility of ultra-wideband (UWB) synthetic aperture radar (SAR) technology for detecting concealed targets in various applications. We have designed and built a vehicle-based, low-frequency UWB SAR radar for proof-of-concept demonstration in detecting obstacles for autonomous navigation, detecting concealed targets (mines, etc.), and mapping internal building structures to locate enemy activity. Although the low-frequency UWB radar technology offers valuable information to complement other technologies due to its penetration capability, it is very difficult to comprehend the radar imagery and correlate the detection list from the radar with the objects in the real world. Using augmented reality (AR) technology, we can superimpose the information from the radar onto the video image of the real world in real-time. Using this, Soldiers would view the environment and the superimposed graphics (SAR imagery, detection locations, digital map, etc.) via a standard display or a head-mounted display. The superimposed information would be constantly changed and adjusted for every perspective and movement of the user. ARL has been collaborating with ITT Industries to implement an AR system that integrates the video data captured from the real world and the information from the UWB radar. ARL conducted an experiment and demonstrated the real-time geo-registration of the two independent data streams. The integration of the AR sub-system into the radar system is underway. This paper presents the integration of the AR and SAR systems. It shows results that include the real-time embedding of the SAR imagery and other information into the video data stream.

  19. Imaging of concrete specimens using inverse synthetic aperture radar

    International Nuclear Information System (INIS)

    Radar Measurement results of laboratory size concrete specimens are presented in this paper. The purpose of this research work is to study various aspects of the radar method in an effort to develop an improved radar system for nondestructive testing of concrete structures. The radar system used for the study is an Inverse Synthetic Aperture Radar (ISAR), which is capable of transmitting microwaves at three different frequency ranges of 2-3.4, 3.4-5.8, and 8-12 GHz. Radar measurement setup is such that the radar is locates 14.4 m away from a concrete target to satisfy a far-field criterion. The concrete target is rotated for 20 degrees during the measurements for the generation of two-dimensional (cross-range) imagery. Concrete targets used for the measurements have the dimensions of 305 mm (width)x305 mm (height)x92 mm (thickness) with different inside configurations. Comparisons are made for dry and wet specimens, specimens with and without inclusions. Each specimen is made to model various situations that a concrete structure can have in reality. Results show that center frequency, frequency bandwidth, and polarization of the incident wave have different effects on identifying the thickness or inclusions inside concrete specimens. Results also suggest that a certain combination of measurement parameters is suitable for a specific application area. Thus, measurement parameters can be optimized for a specific problem. The findings are presented and discussed in details in the paper. Signal processing schemes implemented for imaging of the specimens are also discussed

  20. Wind energy applications of synthetic aperture radar

    DEFF Research Database (Denmark)

    Badger, Merete

    planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning areaddressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore......Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting windfields are valuable in offshore wind energy...... in offshore wind resource assessment isinvestigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive tothe wind speed...

  1. Cancellation of singularities for synthetic aperture radar

    International Nuclear Information System (INIS)

    In a basic model for synthetic aperture radar (SAR) imaging, one wishes to recover a function or distribution f from line integrals over circles whose centers lie on a given curve γ. In this paper, we consider the problem of recovering the singularities (wavefront set) of f given its SAR data, and specifically whether it is possible to choose a singular f whose singularities are hidden from γ, meaning that its SAR data is smooth. We show that f 's singularities can be hidden to leading order if a certain discrete reflection map is the identity, and give examples where this is the case. Finally, numerical experiments illustrate the hiding of singularities. (paper)

  2. Cancellation of singularities for synthetic aperture radar

    Science.gov (United States)

    Caday, Peter

    2015-01-01

    In a basic model for synthetic aperture radar (SAR) imaging, one wishes to recover a function or distribution f from line integrals over circles whose centers lie on a given curve γ. In this paper, we consider the problem of recovering the singularities (wavefront set) of f given its SAR data, and specifically whether it is possible to choose a singular f whose singularities are hidden from γ, meaning that its SAR data is smooth. We show that f 's singularities can be hidden to leading order if a certain discrete reflection map is the identity, and give examples where this is the case. Finally, numerical experiments illustrate the hiding of singularities.

  3. Detection of small, slow ground targets using Synthetic Aperture Radar

    Science.gov (United States)

    Chen, Curtis; Chapin, Elaine; Rosen, Paul

    2005-01-01

    Synthetic aperture radar (SAR) along-track interferometry (ATI) is a technique for sensing Earth-surface motion. The technique involves interferometrically combining data from two radar images acquired from phase centers separated along the platform flight track.

  4. Motion Measurement for Synthetic Aperture Radar.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3 - D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000.

  5. Motion measurement for synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3-D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract AC04-94AL85000.

  6. Multi-mission, autonomous, synthetic aperture radar

    Science.gov (United States)

    Walls, Thomas J.; Wilson, Michael L.; Madsen, David; Jensen, Mark; Sullivan, Stephanie; Addario, Michael; Hally, Iain

    2014-05-01

    Unmanned aerial systems (UASs) have become a critical asset in current battlespaces and continue to play an increasing role for intelligence, surveillance and reconnaissance (ISR) missions. With the development of medium-to-low altitude, rapidly deployable aircraft platforms, the ISR community has seen an increasing push to develop ISR sensors and systems with real-time mission support capabilities. This paper describes recent flight demonstrations and test results of the RASAR (Real-time, Autonomous, Synthetic Aperture Radar) sensor system. RASAR is a modular, multi-band (L and X) synthetic aperture radar (SAR) imaging sensor designed for self-contained, autonomous, real-time operation with mission flexibility to support a wide range of ISR needs within the size, weight and power constraints of Group III UASs. The sensor command and control and real-time image formation processing are designed to allow integration of RASAR into a larger, multi-intelligence system of systems. The multi-intelligence architecture and a demonstration of real-time autonomous cross-cueing of a separate optical sensor will be presented.

  7. Triangulation using synthetic aperture radar images

    Science.gov (United States)

    Wu, Sherman S. C.; Howington-Kraus, Annie E.

    1991-01-01

    For the extraction of topographic information about Venus from stereoradar images obtained from the Magellan Mission, a Synthetic Aperture Radar (SAR) compilation system was developed on analytical stereoplotters. The system software was extensively tested by using stereoradar images from various spacecraft and airborne radar systems, including Seasat, SIR-B, ERIM XCL, and STAR-1. Stereomodeling from radar images was proven feasible, and development is on a correct approach. During testing, the software was enhanced and modified to obtain more flexibility and better precision. Triangulation software for establishing control points by using SAR images was also developed through a joint effort with the Defense Mapping Agency. The SAR triangulation system comprises four main programs, TRIDATA, MODDATA, TRISAR, and SHEAR. The first two programs are used to sort and update the data; the third program, the main one, performs iterative statistical adjustment; and the fourth program analyzes the results. Also, input are flight data and data from the Global Positioning System and Inertial System (navigation information). The SAR triangulation system was tested with six strips of STAR-1 radar images on a VAX-750 computer. Each strip contains images of 10 minutes flight time (equivalent to a ground distance of 73.5 km); the images cover a ground width of 22.5 km. All images were collected from the same side. With an input of 44 primary control points, 441 ground control points were produced. The adjustment process converged after eight iterations. With a 6-m/pixel resolution of the radar images, the triangulation adjustment has an average standard elevation error of 81 m. Development of Magellan radargrammetry will be continued to convert both SAR compilation and triangulation systems into digital form.

  8. Synthetic aperture radar sensors : viable for marine oil spill response?

    International Nuclear Information System (INIS)

    The movement of marine oil spills has been observed and tracked for several years using space borne Synthetic Aperture Radars (SAR). The advantages of SAR for monitoring oil spills include wide field-of-view, foul weather independence, and day/night capabilities. However, SAR displays several shortcomings such as low spatial resolution, long revisit times, no positive means of oil detection, confusion with numerous false targets, and a limited wind speed window in which to observe the oil spill. The authors reviewed the history behind the use of SAR sensors in their capacity as marine oil spill response tools. They presented case studies to better illustrate the benefits of using SAR imagery, in light of the new generation of SAR sensors currently emerging. It is expected that the new SAR sensors coming on stream will enable oil response teams to use the information gathered in a tactical oil spill response. 20 refs., 3 tabs., 5 figs

  9. Mathematical Problems in Synthetic Aperture Radar

    CERN Document Server

    Klein, Jens

    2010-01-01

    This thesis is concerned with problems related to Synthetic Aperture Radar (SAR). The thesis is structured as follows: The first chapter explains what SAR is, and the physical and mathematical background is illuminated. The following chapter points out a problem with a divergent integral in a common approach and proposes an improvement. Numerical comparisons are shown that indicate that the improvements allow for a superior image quality. Thereafter the problem of limited data is analyzed. In a realistic SAR-measurement the data gathered from the electromagnetic waves reflected from the surface can only be collected from a limited area. However the reconstruction formula requires data from an infinite distance. The chapter gives an analysis of the artifacts which can obscure the reconstructed images due to this problem. Additionally, some numerical examples are shown that point to the severity of the problem. In chapter 4 the fact that data is available only from a limited area is used to propose a new invers...

  10. Synthetic aperture radar imaging exploiting multiple scattering

    International Nuclear Information System (INIS)

    In this paper, we consider an imaging scenario, where a bi-static synthetic aperture radar (SAR) system is used in a multiple scattering environment. We consider a ray-theoretic approximation to the Green function to model a multiple scattering environment. This allows us to incorporate the multiple paths followed by the transmitted signal, thereby providing different views of the object to be imaged. However, the received signal from the multiple paths and additive thermal noise may interfere and produce artifacts when standard backprojection-based reconstruction algorithms are used. We use microlocal analysis in a statistical setting to develop a novel filtered-backprojection type image reconstruction method that not only exploits the multi-paths leading to enhancement of the reconstructed image but also suppresses the artifacts due to interference. We assume a priori knowledge of the second-order statistics of the target and noise to suppress the artifacts due to interference in a mean-square error sense. We present numerical simulations to demonstrate the performance of our image reconstruction method. While the focus of this paper is on radar applications, our image formation method is also applicable to other problems arising in fields such as acoustic, geophysical and medical imaging

  11. Multi-static synthetic aperture radar and inverse scattering

    OpenAIRE

    Gustafsson, Mats

    2004-01-01

    In this paper synthetic aperture radar is analyzed from an inverse scattering perspective. It is shown that the classical point scattering model can be generalized to a dipole scattering model. The dipole scattering model reduces to the point scattering model for small aperture angles. For large aperture angles or multiple illumination apertures the dipole model gives an anisotropic reflectivity such that orthogonal scattering processes are separated. Moreover, it is shown th...

  12. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    Andrei Yu Ivanov; Anna I Ginzburg

    2002-09-01

    Continuous observations since 1991 by using synthetic aperture radar (SAR) on board the Almaz-1, ERS-1/2, JERS-1, and RADARSAT satellites support the well-known fact that oceanic eddies are distributed worldwide in the ocean. The paper is devoted to an evaluation of the potential of SAR for detection of eddies and vortical motions in the ocean. The classification of typical vortical features in the ocean detected in remote sensing images (visible, infrared, and SAR) is presented as well as available information on their spatial and temporal scales. Examples of the Almaz-1 and ERS-1/2 SAR images showing different eddy types, such as rings, spiral eddies of the open ocean, eddies behind islands and in bays, spin-off eddies and mushroom-like structures (vortex dipoles) are given and discussed. It is shown that a common feature for most of the eddies detected in the SAR images is a broad spectrum of spatial scales, spiral shape and shear nature. It is concluded that the spaceborne SARs give valuable information on ocean eddies, especially in combination with visible and infrared satellite data.

  13. Synthetic aperture radar signal processing: Trends and technologies

    Science.gov (United States)

    Curlander, John C.

    1993-01-01

    An overview of synthetic aperture radar (SAR) technology is presented in vugraph form. The following topics are covered: an SAR ground data system; SAR signal processing algorithms; SAR correlator architectures; and current and future trends.

  14. Rectification of terrain induced distortions in radar imagery

    Science.gov (United States)

    Kwok, Ronald; Curlander, John C.; Pang, Shirley S.

    1987-01-01

    This paper describes a technique to generate geocoded synthetic aperture radar (SAR) imagery corrected for terrain induced geometric distortions. This algorithm transforms the raw slant range image, generated by the signal processor, into a map registered product, resampled to either Universal Transverse Mercator (UTM) or Polar Stereographic projections, and corrected for foreshortening. The technique utilizes the space platform trajectory information in conjunction with a digital elevation map (DEM) of the target area to generate an ortho-radar map with near-autonomous operation. The current procedure requires only two to three tie-points to compensate for the platform position uncertainty that results in translational error between the image and the DEM. This approach is unique in that it does not require generation of a simulated radar image from the DEM or a grid of tie-points to characterize the image-to-map distortions. Rather, it models the inherent distortions based on knowledge of the radar data collection characteristics, the signal Doppler parameters, and the local terrain height to automatically predict the registration transformation. This algorithm has been implemented on a minicomputer system equipped with an array processor and a large random-access memory to optimize the throughput.

  15. Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations

    Science.gov (United States)

    Lu, Zhong; Mann, Dörte; Freymueller, Jeffrey T.; Meyer, David

    2000-01-01

    ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preemptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by ∼18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by ∼10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was ∼5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km3 and the average thickness of the erupted lava to be ∼7.4 m. Copyright 2000 by the American Geophysical Union.

  16. Oil Slick Characterization Using Synthetic Aperture Radar

    Science.gov (United States)

    Jones, C. E.; Breivik, O.; Brekke, C.; Skrunes, S.; Holt, B.

    2015-12-01

    Oil spills are a hazard worldwide with potential of causing high impact disasters, and require an active oil spill response capability to protect personnel, the ecosystem, and the energy supply. As the amount of oil in traditionally accessible reserves decline, there will be increasing oil extraction from the Arctic and deep-water wells, both new sources with high risk and high cost for monitoring and response. Although radar has long been used for mapping the spatial extent of oil slicks, it is only since the Deepwater Horizon spill that synthetic aperture radar (SAR) has been shown capable of characterizing oil properties within a slick, and therefore useful for directing response to the recoverable thicker slicks or emulsions. Here we discuss a 2015 Norwegian oil-on-water spill experiment in which emulsions of known quantity and water-to-oil ratio along with a look-alike slick of plant oil were released in the North Sea and imaged with polarimetric SAR (PolSAR) by NASA's UAVSAR instrument for several hours following release. During the experiment, extensive in situ measurements were made from ship or aircraft with meteorological instruments, released drift buoys, and optical/IR imagers. The experiment was designed to provide validation data for development of a physical model relating polarization-dependent electromagnetic scattering to the dielectric properties of oil mixed with ocean water, which is the basis for oil characterization with SAR. Data were acquired with X-, C-, and L-band satellite-based SARs to enable multi-frequency comparison of characterization capabilities. In addition, the data are used to develop methods to differentiate mineral slicks from biogenic look-alikes, and to better understand slick weathering and dispersion. The results will provide a basis for modeling oil-in-ice spills, currently a high priority for nations involved in Arctic oil exploration. Here we discuss the Norwegian experiment, the validation data, and the results of

  17. Wind energy applications of synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Bruun Christiansen, M.

    2006-11-15

    Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting wind fields are valuable in offshore wind energy planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning are addressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore wind resource assessment. Firstly, wind wakes behind two large offshore wind farms in Denmark Horns Rev and Nysted are identified. A region of reduced wind speed is found downstream of both wind farms from the SAR wind fields. The wake extent and magnitude depends on the wind speed, the atmospheric stability, and the fraction of turbines operating. Wind farm wake effects are detected up to 20 km downwind of the last turbine. This distance is longer than predicted by state-of-the art wake models. Wake losses are typically 10-20% near the wind farms. Secondly, the potential of using SAR wind maps in offshore wind resource assessment is investigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive to the wind speed and the highest possible accuracy on SAR wind retrievals is therefore sought. A 1.1 m s{sup -1} deviation on the mean wind speed is found through comparison with mast measurements at Horns Rev. The accuracy on mean wind speeds and energy densities found from satellite measurements varies with different empirical model functions. Additional uncertainties are introduced by the infrequent satellite sampling at fixed times of the day. The accuracy on satellite based wind resource

  18. A parametric study of rate of advance and area coverage rate performance of synthetic aperture radar.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hensley, Jr., William H. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Burns, Bryan L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Doerry, Armin Walter [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2014-11-01

    The linear ground distance per unit time and ground area covered per unit time of producing synthetic aperture radar (SAR) imagery, termed rate of advance (ROA) and area coverage rate (ACR), are important metrics for platform and radar performance in surveillance applications. These metrics depend on many parameters of a SAR system such as wavelength, aircraft velocity, resolution, antenna beamwidth, imaging mode, and geometry. Often the effects of these parameters on rate of advance and area coverage rate are non-linear. This report addresses the impact of different parameter spaces as they relate to rate of advance and area coverage rate performance.

  19. Digital Beamforming Synthetic Aperture Radar (DBSAR) Polarimetric Upgrade

    Science.gov (United States)

    Rincon, Rafael F.; Perrine, Martin; McLinden, Matthew; Valett, Susan

    2011-01-01

    The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art radar system developed at NASA/Goddard Space Flight Center for the development and implementation of digital beamforming radar techniques. DBSAR was recently upgraded to polarimetric operation in order to enhance its capability as a science instrument. Two polarimetric approaches were carried out which will be demonstrated in upcoming flight campaigns.

  20. A fast autofocus algorithm for synthetic aperture radar processing

    DEFF Research Database (Denmark)

    Dall, Jørgen

    1992-01-01

    High-resolution synthetic aperture radar (SAR) imaging requires the motion of the radar platform to be known very accurately. Otherwise, phase errors are induced in the processing of the raw SAR data, and bad focusing results. In particular, a constant error in the measured along-track velocity...... or the cross-track acceleration leads to a phase error that varies quadratically over the synthetic aperture. The process of estimating this quadratic phase error directly from the radar data is termed autofocus. A novel autofocus algorithm with a computational complexity which is at least an order...

  1. On the soil roughness parameterization problem in soil moisture retrieval of bare surfaces from Synthetic Aperture Radar 1959

    Science.gov (United States)

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unles...

  2. Synthetic aperture radar imaging with motion estimation and autofocus

    International Nuclear Information System (INIS)

    We introduce from first principles a synthetic aperture radar (SAR) imaging and target motion estimation method that is combined with compensation for radar platform trajectory perturbations. The main steps of the method are (a) segmentation of the data into properly calibrated small apertures, (b) motion or platform trajectory perturbation estimation using the Wigner transform and the ambiguity function of the data in a complementary way and (c) combination of small aperture estimates and construction of high-resolution images over wide apertures. The analysis provides quantitative criteria for implementing the aperture segmentation and the parameter estimation process. X-band persistent surveillance SAR is a specific application that is covered by our analysis. Detailed numerical simulations illustrate the robust applicability of the theory and validate the theoretical resolution analysis. (paper)

  3. Lynx: A High-Resolution Synthetic Aperture Radar

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, A.W.; Hensley, W.H.; Pace, F.; Stence, J.; Tsunoda, S.I.; Walker, B.C.; Woodring, M.

    1999-03-08

    Lynx is a high resolution, synthetic aperture radar (SAR) that has been designed and built by Sandia National Laboratories in collaboration with General Atomics (GA). Although Lynx may be operated on a wide variety of manned and unmanned platforms, it is primarily intended to be fielded on unmanned aerial vehicles. In particular, it may be operated on the Predator, I-GNAT, or Prowler II platforms manufactured by GA Aeronautical Systems, Inc. The Lynx production weight is less than 120 lb. and has a slant range of 30 km (in 4 mm/hr rain). It has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode. In ground moving target indicator mode, the minimum detectable velocity is 6 knots with a minimum target cross-section of 10 dBsm. In coherent change detection mode, Lynx makes registered, complex image comparisons either of 0.1 m resolution (minimum) spotlight images or of 0.3 m resolution (minimum) strip images. The Lynx user interface features a view manager that allows it to pan and zoom like a video camera. Lynx was developed under corporate finding from GA and will be manufactured by GA for both military and commercial applications. The Lynx system architecture will be presented and some of its unique features will be described. Imagery at the finest resolutions in both spotlight and strip modes have been obtained and will also be presented.

  4. Observations of the marine environment from spaceborne side-looking real aperture radars

    Science.gov (United States)

    Kalmykov, A. I.; Velichko, S. A.; Tsymbal, V. N.; Kuleshov, Yu. A.; Weinman, J. A.; Jurkevich, I.

    1993-01-01

    Real aperture, side looking X-band radars have been operated from the Soviet Cosmos-1500, -1602, -1766 and Ocean satellites since 1984. Wind velocities were inferred from sea surface radar scattering for speeds ranging from approximately 2 m/s to those of hurricane proportions. The wind speeds were within 10-20 percent of the measured in situ values, and the direction of the wind velocity agreed with in situ direction measurements within 20-50 deg. Various atmospheric mesoscale eddies and tropical cyclones were thus located, and their strengths were inferred from sea surface reflectivity measurements. Rain cells were observed over both land and sea with these spaceborne radars. Algorithms to retrieve rainfall rates from spaceborne radar measurements were also developed. Spaceborne radars have been used to monitor various marine hazards. For example, information derived from those radars was used to plan rescue operations of distressed ships trapped in sea ice. Icebergs have also been monitored, and oil spills were mapped. Tsunamis produced by underwater earthquakes were also observed from space by the radars on the Cosmos 1500 series of satellites. The Cosmos-1500 satellite series have provided all weather radar imagery of the earths surface to a user community in real time by means of a 137.4 MHz Automatic Picture Transmission channel. This feature enabled the radar information to be used in direct support of Soviet polar maritime activities.

  5. Synthetic Aperture Radar (SAR) data processing

    Science.gov (United States)

    Beckner, F. L.; Ahr, H. A.; Ausherman, D. A.; Cutrona, L. J.; Francisco, S.; Harrison, R. E.; Heuser, J. S.; Jordan, R. L.; Justus, J.; Manning, B.

    1978-01-01

    The available and optimal methods for generating SAR imagery for NASA applications were identified. The SAR image quality and data processing requirements associated with these applications were studied. Mathematical operations and algorithms required to process sensor data into SAR imagery were defined. The architecture of SAR image formation processors was discussed, and technology necessary to implement the SAR data processors used in both general purpose and dedicated imaging systems was addressed.

  6. Synthetic aperture radar system design for random field classification

    Science.gov (United States)

    Harger, R. O.

    1973-01-01

    An optimum design study is carried out for synthetic aperture radar systems intended for classifying randomly reflecting areas (such as agricultural fields) characterized by a reflectivity density spectral density. The problem solution is obtained, neglecting interfield interference and assuming areas of known configuration and location, as well as a certain Gaussian signal field property. The optimum processor is nonlinear, but includes conventional matched filter processing. A set of summary design curves is plotted, and is applied to the design of a satellite synthetic aperture radar system.

  7. Polarimetric synthetic aperture radar data and the complex Wishart distribution

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2003-01-01

    When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart distribu......When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart...

  8. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging

    OpenAIRE

    Shuanghui Zhang; Yongxiang Liu; Xiang Li; Guoan Bi

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed met...

  9. Nonlinear ocean internal waves observed by multifrequency synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    YANG Jingsong; XIAO Qingmei; HUANG Weigen; FU Bin; CHEN Peng

    2008-01-01

    A numerical model which consists of the Korteweg-de Vries (KdV) equation, the action balance equation and the radar backscat- tering model is developed to simulate the frequency dependence of synthetic aperture radar (SAR) remote sensing of nonlinear o- cean internal waves. Muhifrequency data collected by NASA SIR - C SAR and NASA JPL AIRSAR are used as comparison. Case studies show that the results of simulation agree well with the results of SAR data.

  10. Bistatic Synthetic Aperture Radar Point Spread Function Characteristic Analysis

    Institute of Scientific and Technical Information of China (English)

    HU Cheng; ZENG Tao; ZENG Hai-bin

    2007-01-01

    Based on the point spread function (PSF) theory, the side-lobe extension direction of the impulse response in bistatic synthetic aperture radar (BSAR) is analyzed in detail;in addition, the corresponding auto-focus in BSAR should be considered along iso-range direction, not the traditional azimuth resolution (AR) direction.The conclusion is verified by the computer simulation.

  11. Wind retrieval from synthetic aperture radar - an overview

    DEFF Research Database (Denmark)

    Dagestad, Knut-Frode; Horstmann, Jochen; Mouche, Alexis;

    2013-01-01

    This paper represents a consensus on the state-of-the-art in wind retrieval using synthetic aperture radar (SAR), after the SEASAR 2012 workshop “Advances in SAR Oceanography” hosted by the European Space Agency (ESA) and the Norwegian Space Centre in Tromsø, Norway 18–22 June 2012. We document t...

  12. Offshore Wind Potential in South India from Synthetic Aperture Radar

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Bingöl, Ferhat; Badger, Merete;

    The offshore wind energy potential for pre-feasibility in South India in the area from 77° to 80° Eastern longitude and 7° to 10° Northern latitude is observed from a total of 164 ENVISAT Advanced Synthetic Aperture Radar (ASAR) satellite images during the years 2002 to 2011. All satellite scenes...

  13. Geometric rectification of radar imagery using digital elevation models

    Science.gov (United States)

    Naraghi, M.; Stromberg, W.; Daily, M.

    1983-01-01

    Geologic analysis of radar imagery requires accurate spatial rectification to allow rock type discrimination and meaningful exploitation of multisensor data files. A procedure is described which removes distortions produced by most sources including the heretofore elusive problem of terrain induced effects. Rectified imagery is presented which displays geologic features not apparent in the distorted data.

  14. Time-frequency analysis of synthetic aperture radar signals

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, B.

    1996-08-01

    Synthetic aperture radar (SAR) has become an important tool for remote sensing of the environment. SAR is a set of digital signal processing algorithms that are used to focus the signal returned to the radar because radar systems in themselves cannot produce the high resolution images required in remote sensing applications. To reconstruct an image, several parameters must be estimated and the quality of output image depends on the degree of accuracy of these parameters. In this thesis, we derive the fundamental SAR algorithms and concentrate on the estimation of one of its critical parameters. We show that the common technique for estimating this particular parameter can sometimes lead to erroneous results and reduced quality images. We also employ time-frequency analysis techniques to examine variations in the radar signals caused by platform motion and show how these results can be used to improve output image quality.

  15. Synthetic impulse and aperture radar (SIAR) a novel multi-frequency MIMO radar

    CERN Document Server

    Chen, Baixiao

    2014-01-01

    Analyzes and discusses the operating principle, signal processing method, and experimental results of this advanced radar technology This book systematically discusses the operating principle, signal processing method, target measurement technology, and experimental results of a new kind of radar called synthetic impulse and aperture radar (SIAR). The purpose is to help readers acquire an insight into the concept and principle of the SIAR, to know its operation mode, signal processing method, the difference between the traditional radar and itself, the designing ideals, and the developing me

  16. Probing the Martian Subsurface with Synthetic Aperture Radar

    Science.gov (United States)

    Campbell, B. A.; Maxwell, T. A.; Freeman, A.

    2005-01-01

    Many regions of the martian surface are covered by fine-grained materials emplaced by volcanic, fluvial, or aeolian processes. These mantling deposits likely hide ancient channel systems (particularly at smaller scale lengths) and volcanic, impact, glacial, or shoreline features. Synthetic aperture radar (SAR) offers the capability to probe meters below the surface, with imaging resolution in the 10 s of m range, to reveal the buried terrain and enhance our understanding of Mars geologic and climate history. This presentation focuses on the practical applications of a Mars orbital SAR, methods for polarimetric and interferometric radar studies, and examples of such techniques for Mars-analog sites on the Moon and Earth.

  17. Synthetic Aperture Radar : A Focus on Current Problems.

    Directory of Open Access Journals (Sweden)

    M.S. Ranga Rao

    1997-10-01

    Full Text Available Synthetic aperture radar (SAR is a powerful tool for mapping and remote sensing. The theory and operation of SAR have seen a period of intense activity in recent years. This paper attempts to review some of the more advanced topics studied in connection with madern SAR systems based on digital processing . Following a brief review of the principles involved in the operation of SAR, attention is focussed on special topics such as advanced SAR modelling and ffocussing techniques, in particular clutterlock and autofocus, Doppler centroid (DC estimation methods involving seismic migration technique, moving target, biststic radar imaging , effects of system nonlinearities,etc.

  18. Materials identification synthetic aperture radar: progress toward a realized capability

    International Nuclear Information System (INIS)

    Most non-metallic materials have frequency-dependent reflectivity functions, that is, they reflect electromagnetic energy in a manner that depends on frequency. Pulsed-chirped synthetic aperture radar and other multispectral radar systems do not generally take into account the frequency dependence of material reflections in forming scenes or making other inferences. In this report, we introduce a simple mathematical approach to using existing pulsed chirp synthetic aperture systems in a manner which results in a determination of a frequency-dependent reflectivity function for each pixel in a computed scene. Our analysis of collected data suggests that the method may be useful to distinguish disturbed from non-disturbed earth, and to detect chemicals on the surface of the earth. The method we have developed provides the analyst with a vector above each pixel with each vector component referencing a frequency band. This additional information may be useful for considering surface texture, subsurface layering and materials identification. (paper)

  19. Seamless Synthetic Aperture Radar Archive for Interferometry Analysis

    OpenAIRE

    S. Baker; C. Baru; Bryson, G; Buechler, B.; Crosby, C.; Fielding, E.; Meertens, C.; Nicoll, J.; Youn, C.

    2014-01-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived interferometric SAR (InSAR) data products. A unified application programming interface...

  20. Inverse synthetic aperture radar imaging principles, algorithms and applications

    CERN Document Server

    Chen , Victor C

    2014-01-01

    Inverse Synthetic Aperture Radar Imaging: Principles, Algorithms and Applications is based on the latest research on ISAR imaging of moving targets and non-cooperative target recognition (NCTR). With a focus on the advances and applications, this book will provide readers with a working knowledge on various algorithms of ISAR imaging of targets and implementation with MATLAB. These MATLAB algorithms will prove useful in order to visualize and manipulate some simulated ISAR images.

  1. Passive Interferometric Ocean Currents Observation Synthetic Aperture Radar (PICOSAR)

    OpenAIRE

    Börner, Thomas; López-Dekker, Paco; Krieger, Gerhard; Bachmann, Markus; Moreira, Alberto; Müller, Hartmut

    2014-01-01

    This chapter describes PICOSAR (Passive Interferometric Ocean Currents Observation Synthetic Aperture Radar), a concept consisting of two small, low-cost and low power spacecraft carrying a passive, receive-only SAR payload. PICOSAR enhances the functionality of a full SAR system such as Sentinel-1 or TerraSAR-X by adding a unique along-track interferometer dedicated to ocean surface current measurements. The passive nature of this system and the focus on a single application and single opera...

  2. A FUZZY LOGIC-BASED APPROACH FOR THE DETECTION OF FLOODED VEGETATION BY MEANS OF SYNTHETIC APERTURE RADAR DATA

    OpenAIRE

    Tsyganskaya, V.; S. Martinis; A. Twele; Cao, W.; Schmitt, A.; P. Marzahn; R. Ludwig

    2016-01-01

    In this paper an algorithm designed to map flooded vegetation from synthetic aperture radar (SAR) imagery is introduced. The approach is based on fuzzy logic which enables to deal with the ambiguity of SAR data and to integrate multiple ancillary data containing topographical information, simple hydraulic considerations and land cover information. This allows the exclusion of image elements with a backscatter value similar to flooded vegetation, to significantly reduce misclassification error...

  3. Smart antennas for space-borne synthetic aperture radars

    Science.gov (United States)

    Qin, F.; Gao, S.; Mao, C.; Wang, Z.; Patyuchenko, A.; Younis, M.; Krieger, G.

    2015-11-01

    This paper discusses smart antennas for space-borne synthetic aperture radar (SAR). First, some recent development in smart antennas for space-borne SAR is reviewed. Then, the paper presents a low-cost space-borne SAR system using digital beam forming on receive. The smart antenna system is also discussed, and some results are shown. The antenna system, consisting of a parabolic reflector and multi-feed array, is designed and optimized for dual-band dual-polarized digital beam-forming performance. The operating frequencies are at X and Ka bands with the center frequency of 9.6 and 35.75 GHz, respectively. The stacked dipoles and square patches with parasitic elements are employed as the feed elements at X and Ka bands. Dual-band antenna arrays are combined in the same aperture, which not only reduce the aperture of the feed array, but also coincide the center of dual-band feed arrays.

  4. Signal processing techniques for forward imaging using ultrawideband synthetic aperture radar

    Science.gov (United States)

    Nguyen, Lam H.; Ton, Tuan T.; Wong, David C.; Ressler, Marc A.

    2003-09-01

    The U.S. Army Research Laboratory (ARL), as part of a customer and mission-funded exploratory development program, has been developing a prototype of low-frequency, ultra-wideband (UWB) forward-imaging synthetic aperture radar (SAR) to support the U.S. Army's vision for increased mobility and survivability of unmanned ground vehicle missions. The ability of the UWB radar technology to detect objects under foilage could provide an important obstacle-avoidance capability for robotic vehicles, which could improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U.S. forces. In a recent experiment at Aberdeen Proving Ground (APG), we exercised the UWB SAR radar in forward-looking mode and collected data to support the investigation. This paper discusses the signal processing algorithms and techniques that we developed and applied to the recent UWB SAR forward-looking data. The algorithms include motion data processing, self-interference signal (SIR) removal, radio frequency interference (RFI) signal removal, forward-looking image formation, and visualization techniques. We present forward-loking SAR imagery and also volumetric imagery of some targets.

  5. Synthetic aperture radar data visualization on the iPod Touch

    Science.gov (United States)

    Fouts, Aaron; Vickery, Rhonda; Majumder, Uttam; Burchett, Tracy; Klein, Troy; Minardi, Michael

    2010-04-01

    A major area of focus for the Air Force is sensor performance in urban environments. Aircraft with multiple sensor modalities, such as Synthetic Aperture RADAR (SAR), Infrared (IR), and Electro-Optics (EO), are essential for intelligence, surveillance, and reconnaissance (ISR) of current and future urban battlefields. Although applications exist for visualization of these types of imagery, they usually require at least a laptop computer and internet connection. Field operatives need to be able to access georeferenced information about imagery as part of a Geographic Information System (GIS) on mobile devices. The iPod/iPhone has a 640x480 resolution multi-touch display, making it an excellent device for interacting with georeferenced imagery. We created an iPhone application that loads SAR imagery and allows the user to interact with it. The user multi-touch interface provides pan and zoom capabilities as well as options to change parameters relating to the query. We describe how operatives in the field can use this application to investigate SAR and GIS related problems on the iPhone mobile device, which otherwise would require a computer and Internet connection.

  6. INTERFEROMETRIC SYNTHETIC APERTURE RADAR (INSAR TECHNOLOGY AND GEOMORPHOLOGY INTERPRETATION

    Directory of Open Access Journals (Sweden)

    M. Maghsoudi

    2013-09-01

    Full Text Available Geomorphology is briefly the study of landforms and their formative processes on the surface of the planet earth as human habitat. The landforms evolution and the formative processes can best be studied by technologies with main application in study of elevation. Interferometric Synthetic Aperture Radar (InSAR is the appropriate technology for this application. With phase differences calculations in radar waves, the results of this technology can extensively be interpreted for geomorphologic researches. The purpose of the study is to review the geomorphologic studies using InSAR and also the technical studies about InSAR with geomorphologic interpretations. This study states that the InSAR technology can be recommended to be employed as a fundamental for geomorphology researches.

  7. Passive synthetic aperture radar imaging of ground moving targets

    Science.gov (United States)

    Wacks, Steven; Yazici, Birsen

    2012-05-01

    In this paper we present a method for imaging ground moving targets using passive synthetic aperture radar. A passive radar imaging system uses small, mobile receivers that do not radiate any energy. For these reasons, passive imaging systems result in signicant cost, manufacturing, and stealth advantages. The received signals are obtained by multiple airborne receivers collecting scattered waves due to illuminating sources of opportunity such as commercial television, radio, and cell phone towers. We describe a novel forward model and a corresponding ltered-backprojection type image reconstruction method combined with entropy optimization. Our method determines the location and velocity of multiple targets moving at dierent velocities. Furthermore, it can accommodate arbitrary imaging geometries. we present numerical simulations to verify the imaging method.

  8. Synthetic aperture radar images with composite azimuth resolution

    Energy Technology Data Exchange (ETDEWEB)

    Bielek, Timothy P; Bickel, Douglas L

    2015-03-31

    A synthetic aperture radar (SAR) image is produced by using all phase histories of a set of phase histories to produce a first pixel array having a first azimuth resolution, and using less than all phase histories of the set to produce a second pixel array having a second azimuth resolution that is coarser than the first azimuth resolution. The first and second pixel arrays are combined to produce a third pixel array defining a desired SAR image that shows distinct shadows of moving objects while preserving detail in stationary background clutter.

  9. Monitoring coastal inundation with Synthetic Aperture Radar satellite data

    Science.gov (United States)

    Suzuoki, Yukihiro; Rangoonwala, Amina; Ramsey, Elijah W., III

    2011-01-01

    Maps representing the presence and absence of surface inundation in the Louisiana coastal zone were created from available satellite scenes acquired by the Japanese Aerospace Exploration Agency's Advanced Land Observing Satellite and by the European Space Agency's Envisat from late 2006 through summer 2009. Detection of aboveground surface flooding relied on the well-documented and distinct signature of decreased backscatter in Synthetic Aperture Radar (SAR), which is indicative of inundated marsh in the Gulf of Mexico. Even though decreases in backscatter were distinctive, the multiplicity of possible interactions between changing flood depths and canopy height yielded complex SAR-based representations of the marshes.

  10. Imaging frequency-dependent reflectivity from synthetic-aperture radar

    International Nuclear Information System (INIS)

    This paper develops a method for using a synthetic-aperture radar system to obtain not only a spatial image of a scene but also the localized frequency dependence of the scene reflectivity. In other words, for each image pixel, we also obtain a plot of the frequency dependence of the reflectivity in that pixel. We present a method for extracting this information from the data, and also a formula that characterizes the performance of this imaging system. We conclude with some simulations suggesting that the method may be promising. (paper)

  11. Synthetic Aperture Radar Raw Signals Simulation of Extended Scenes

    Institute of Scientific and Technical Information of China (English)

    Sun Jin-yao; Sun Hong

    2004-01-01

    A synthetic aperture radar (SAR) raw signal simulation algorithm for extended scenes is presented. This algorithm is based on the SAR two-dimensional system transform function (STF). To cope with range-variant nature of SAR STF and increase the speed of this algorithm, new formulas for range-variant phase corrections in range Doppler (RD) domain are developed. In this way, many azimuth lines can be simulated with the same SAR STF. It only needs twodimensional fast Fourier transform code and complex multiplications. Comparing with time-domain simulation algorithm, it is very simple and thus efficient. Simulation results have shown that this algorithm is accurate and efficient.

  12. Imaging algorithms for synthetic aperture ultra-wideband radar

    International Nuclear Information System (INIS)

    Synthetic aperture ultra-wideband radar images is an important emerging technology with the potential to produce high-resolution images for a variety of applications, including the nondestructive evaluation of civil structures, minefield clearing, unexploded ordnance detection and removal, hazardous waste identification, and detection of miscellaneous buried objects. In FY-93, the authors developed imaging software for two- and three-dimensional problems for several geometries, and produced high-resolution images of a laboratory concrete test-bed and of a simulated mine field located at Lawrence Livermore National Laboratory's Nevada Test Site

  13. Apodized RFI filtering of synthetic aperture radar images

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    Fine resolution Synthetic Aperture Radar (SAR) systems necessarily require wide bandwidths that often overlap spectrum utilized by other wireless services. These other emitters pose a source of Radio Frequency Interference (RFI) to the SAR echo signals that degrades SAR image quality. Filtering, or excising, the offending spectral contaminants will mitigate the interference, but at a cost of often degrading the SAR image in other ways, notably by raising offensive sidelobe levels. This report proposes borrowing an idea from nonlinear sidelobe apodization techniques to suppress interference without the attendant increase in sidelobe levels. The simple post-processing technique is termed Apodized RFI Filtering (ARF).

  14. Image formation for synthetic aperture radar using MATLAB

    OpenAIRE

    Cequiel Mir, Mireia

    2008-01-01

    The study of SAR (Synthetic Aperture Radar) image formation using MATLAB it is explained in the following project. The main to use MATLAB in this project was the most important thing to choose it. As MATLAB it is one of the most tools used by engineers, I considered really interesting the project, and moreover with the image treatment that it involved. The study of this field requires some background information to identify the steps which must be done to obtain some results. SAR images tr...

  15. Experiment in Onboard Synthetic Aperture Radar Data Processing

    Science.gov (United States)

    Holland, Matthew

    2011-01-01

    Single event upsets (SEUs) are a threat to any computing system running on hardware that has not been physically radiation hardened. In addition to mandating the use of performance-limited, hardened heritage equipment, prior techniques for dealing with the SEU problem often involved hardware-based error detection and correction (EDAC). With limited computing resources, software- based EDAC, or any more elaborate recovery methods, were often not feasible. Synthetic aperture radars (SARs), when operated in the space environment, are interesting due to their relevance to NASAs objectives, but problematic in the sense of producing prodigious amounts of raw data. Prior implementations of the SAR data processing algorithm have been too slow, too computationally intensive, and require too much application memory for onboard execution to be a realistic option when using the type of heritage processing technology described above. This standard C-language implementation of SAR data processing is distributed over many cores of a Tilera Multicore Processor, and employs novel Radiation Hardening by Software (RHBS) techniques designed to protect the component processes (one per core) and their shared application memory from the sort of SEUs expected in the space environment. The source code includes calls to Tilera APIs, and a specialized Tilera compiler is required to produce a Tilera executable. The compiled application reads input data describing the position and orientation of a radar platform, as well as its radar-burst data, over time and writes out processed data in a form that is useful for analysis of the radar observations.

  16. Precipitation observations from high frequency spaceborne polarimetric synthetic aperture radar and ground-based radar: Theory and model validation

    Science.gov (United States)

    Fritz, Jason P.

    Global weather monitoring is a very useful tool to better understand the Earth's hydrological cycle and provide critical information for emergency and warning systems in severe cases. Developed countries have installed numerous ground-based radars for this purpose, but they obviously are not global in extent. To address this issue, the Tropical Rainfall Measurement Mission (TRMM) was launched in 1997 and has been quite successful. The follow-on Global Precipitation Measurement (GPM) mission will replace TRMM once it is launched. However, a single precipitation radar satellite is still limited, so it would be beneficial if additional existing satellite platforms can be used for meteorological purposes. Within the past few years, several X-band Synthetic Aperture Radar (SAR) satellites have been launched and more are planned. While the primary SAR application is surface monitoring, and they are heralded as "all weather'' systems, strong precipitation induces propagation and backscatter effects in the data. Thus, there exists a potential for weather monitoring using this technology. The process of extracting meteorological parameters from radar measurements is essentially an inversion problem that has been extensively studied for radars designed to estimate these parameters. Before attempting to solve the inverse problem for SAR data, however, the forward problem must be addressed to gain knowledge on exactly how precipitation impacts SAR imagery. This is accomplished by simulating storms in SAR data starting from real measurements of a storm by ground-based polarimetric radar. In addition, real storm observations by current SAR platforms are also quantitatively analyzed by comparison to theoretical results using simultaneous acquisitions by ground radars even in single polarization. For storm simulation, a novel approach is presented here using neural networks to accommodate the oscillations present when the particle scattering requires the Mie solution, i

  17. Experiments on a Ground-Based Tomographic Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Hoonyol Lee

    2016-08-01

    Full Text Available This paper presents the development and experiment of three-dimensional image formation by using a ground-based tomographic synthetic aperture radar (GB-TomoSAR system. GB-TomoSAR formulates two-dimensional synthetic aperture by the motion of antennae, both in azimuth and vertical directions. After range compression, three-dimensional image focusing is performed by applying Deramp-FFT (Fast Fourier Transform algorithms, both in azimuth and vertical directions. Geometric and radiometric calibrations were applied to make an image cube, which is then projected into range-azimuth and range-vertical cross-sections for visualization. An experiment with a C-band GB-TomoSAR system with a scan length of 2.49 m and 1.86 m in azimuth and vertical-direction, respectively, shows distinctive three-dimensional radar backscattering of stable buildings and roads with resolutions similar to the theoretical values. Unstable objects such as trees and moving cars generate severe noise due to decorrelation during the eight-hour image-acquisition time.

  18. Filtering and segmentation of the Cassini synthetic aperture radar images on Titan

    Science.gov (United States)

    Bratsolis, E.; Bampasidis, G.; Solomonidou, A.; Coustenis, A.; Hirtzig, M.

    2011-10-01

    A filtering technique is applied to obtain the restored synthetic aperture radar (SAR) images. One of the major problems hampering the derivation of meaningful texture information from SAR imagery is the speckle noise. It overlays "real" structures and causes gray value variations even in homogeneous parts of the image. Our method, the TSPR (total sum preserving regularization) filter, is based on probabilistic methods and regards an image as a random element drawn from a prespecified set of possible images optimized by a synchronous local iterative method. The despeckle filter can be used as intermediate stage for the extraction of meaningful regions that correspond to structural units in the scene or distinguish objects of interest like lakes, drainage networks, equatorial dunes or impact craters, where different textures appear.

  19. Temporal stability of soil moisture and radar backscatter observed by the advanced Synthetic Aperture Radar (ASAR)

    OpenAIRE

    Alexander Löw; José Martínez-Fernández; Klaus Scipal; Günter Blöschl; Stefan Hasenauer; Annett Bartsch; Daniel Sabel; Marcela Doubkova; Carsten Pathe; Wolfgang Wagner

    2008-01-01

    The high spatio-temporal variability of soil moisture is the result of atmospheric forcing and redistribution processes related to terrain, soil, and vegetation characteristics. Despite this high variability, many field studies have shown that in the temporal domain soil moisture measured at specific locations is correlated to the mean soil moisture content over an area. Since the measurements taken by Synthetic Aperture Radar (SAR) instruments are very sensitive to soil moisture it is hypoth...

  20. Polarization Hierarchy and System Operating Architecture for Polarimetric Synthetic Aperture Radar

    OpenAIRE

    Yang Ruliang; Dai Bowei; Li Haiying

    2016-01-01

    Polarization hierarchy and system operating architecture is one of the key technologies for Polarimetric Synthetic Aperture Radar (PolSAR) system design. In this paper the polarization hierarchies of PolSAR, including Single-Polarization radar, Dual-Polarization radar, Full-Polarization radar, and Compact Polarization radar, are discussed. In addition, the system operating architectures such as Polarization Timedivision multiplexing pulse, Polarization Frequency-division multiplexing pulse, P...

  1. Performance limits for maritime Inverse Synthetic Aperture Radar (ISAR).

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2013-11-01

    The performance of an Inverse Synthetic Aperture Radar (ISAR) system depends on a variety of factors, many which are interdependent in some manner. In this report we specifically examine ISAR as applied to maritime targets (e.g. ships). It is often difficult to get your arms around the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall ISAR system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the seek time.

  2. Offshore wind potential in South India from synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Hasager, C.B.; Bingoel, F.; Badger, M.; Karagali, I.; Sreevalsan, E.

    2011-10-15

    The offshore wind energy potential for pre-feasibility in South India in the area from 77 deg. to 80 deg. Eastern longitude and 7 deg. to 10 deg. Northern latitude is observed from a total of 164 ENVISAT Advanced Synthetic Aperture Radar (ASAR) satellite images during the years 2002 to 2011. All satellite scenes are from Wide Swath Mode and each cover approximately 400 km by 400 km. The ocean wind speed maps are retrieved and processed at Risoe DTU. The results show wind energy density from 200 W/m2 to 500 W/m2 at 10 m height above sea level. QuikSCAT ocean winds are included as background information on the 10-year mean and a general description of the winds and climate with monsoons in India is presented. (Author)

  3. Lunar cartography with the Apollo 17 ALSE radar imagery

    Science.gov (United States)

    Tiernan, M.; Roth, L.; Thompson, T. W.; Elachi, C.; Brown, W. E., Jr.

    1976-01-01

    Lunar position differences between thirteen craters in Mare Serenitatis were computed from VHF radar-imagery obtained by the Lunar Sounder instrument flown on the Apollo 17 command module. The radar-derived position differences agree with those obtained by conventional photogrammetric reductions of Apollo metric photography. This demonstrates the feasibility of using the Apollo Lunar Sounder data to determine the positions of lunar features along the Apollo 17 orbital tracks. This will be particularly useful for western limb and farside areas, where no Apollo metric camera pictures are available.

  4. Radar imagery from the 1994 Lock Linnhe ship wake experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mullenhoff, C.J.; Lehman, S.K.; Jones, H. [Lawrence Livermore National Lab., CA (United States)] [and others

    1994-11-15

    The 1994 Loch Linnhe radar ocean imaging trials were held from September 4 through September 17. Two ships were used: the R.V. Colonel Templer, and the RMAS Collie. Thorn EMI, Inc., fielded a dual band, dual polarization radar on a hillside overlooking the loch. A primary purpose of the experiment was to obtain highly visible images of ship generated internal waves. Presented here is imagery for a few of the good ship runs, as well as a study of the environment of the visibility of ship generated internal waves.

  5. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    Science.gov (United States)

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  6. Synthetic-aperture radar imaging through dispersive media

    International Nuclear Information System (INIS)

    In this paper we develop a method for synthetic-aperture radar (SAR) imaging through a dispersive medium. We consider the case when the sensor and scatterers are embedded in a known homogeneous dispersive material, the scene to be imaged lies on a known surface and the radar antenna flight path is an arbitrary but known smooth curve. The scattering is modeled using a linearized (Born) scalar model. We assume that the measurements are polluted with additive noise. Furthermore, we assume that we have prior knowledge about the power-spectral densities of the scene and the noise. This leads us to formulate the problem in a statistical framework. We develop a filtered-back-projection imaging algorithm in which we choose the filter according to the statistical properties of the scene and noise. We present numerical simulations for a case where the scene consists of point-like scatterers located on the ground, and demonstrate how the ability to resolve the targets depends on a quantity which we call the noise-to-target ratio. In our simulations, the dispersive material is modeled with the Fung–Ulaby equations for leafy vegetation. However, the method is also applicable to other dielectric materials where the dispersion is considered relevant in the frequency range of the transmitted signals

  7. Three-dimensional subsurface imaging synthetic aperture radar

    International Nuclear Information System (INIS)

    The objective of this applied research and development project is to develop a system known as '3-D SISAR'. This system consists of a ground penetrating radar with software algorithms designed for the detection, location, and identification of buried objects in the underground hazardous waste environments found at DOE storage sites. Three-dimensional maps of the object locations will be produced which can assist the development of remediation strategies and the characterization of the digface during remediation operations. It is expected that the 3-D SISAR will also prove useful for monitoring hydrocarbon based contaminant migration after remediation. The underground imaging technique being developed under this contract utilizes a spotlight mode Synthetic Aperture Radar (SAR) approach which, due to its inherent stand-off capability, will permit the rapid survey of a site and achieve a high degree of productivity over large areas. When deployed from an airborne platform, the stand-off techniques is also seen as a way to overcome practical survey limitations encountered at vegetated sites

  8. Interferometric synthetic aperture radar: building tomorrow's tools today

    Science.gov (United States)

    Lu, Zhong

    2006-01-01

    A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface. Part of the energy is reflected back to the SAR system and recorded. Using a sophisticated image processing technique, called SAR processing (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image representing the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets, slowing of the signal by the atmosphere, and the interaction of EM waves with ground surface. Interferometric SAR (InSAR) imaging, a recently developed remote sensing technique, utilizes the interaction of EM waves, referred to as interference, to measure precise distances. Very simply, InSAR involves the use of two or more SAR images of the same area to extract landscape topography and its deformation patterns.

  9. Ground Processing of Cassini RADAR Imagery of Titan

    OpenAIRE

    Stiles, Bryan W.; Gim, Yonggyu; Hamilton, Gary; Hensley, Scott; Johnson, William T. K.; Shimada, Joanne; West, Richard D.; Callahan, Phil

    2006-01-01

    The Cassini RADAR instrument onboard the Cassini Orbiter is currently collecting SAR Imagery of the surface of Saturn's largest moon, Titan. This paper describes the ground processing of Cassini SAR data. We focus upon the unusual features of the data and how these features impact the processing. We exhibit a data dependent mechanism we have implemented for eliminating artifacts due to attitude and ephemeris knowledge error. Finally we describe how we trade-off SAR ...

  10. A new polarimetric change detector in radar imagery

    OpenAIRE

    Marino, Armando; Cloude, Shane R.; Lopez-Sanchez, Juan M.

    2013-01-01

    In modern society, the anthropogenic influences on ecosystems are central points to understand the evolution of our planet. A polarimetric synthetic aperture radar may have a significant contribution in tackling problems concerning land use change, since such data are available with any-weather conditions. Additionally, the discrimination capability can be enhanced by the polarimetric analysis. Recently, an algorithm able to identify targets scattering an electromagnetic wave with any degree ...

  11. Autofocus algorithm for synthetic aperture radar imaging with large curvilinear apertures

    International Nuclear Information System (INIS)

    An approach to autofocusing for large curved synthetic aperture radar (SAR) apertures is presented. Its essential feature is that phase corrections are being extracted not directly from SAR images, but rather from reconstructed SAR phase-history data representing windowed patches of the scene, of sizes sufficiently small to allow the linearization of the forward- and back-projection formulae. The algorithm processes data associated with each patch independently and in two steps. The first step employs a phase-gradient-type method in which phase correction compensating (possibly rapid) trajectory perturbations are estimated from the reconstructed phase history for the dominant scattering point on the patch. The second step uses phase-gradient-corrected data and extracts the absolute phase value, removing in this way phase ambiguities and reducing possible imperfections of the first stage, and providing the distances between the sensor and the scattering point with accuracy comparable to the wavelength. The features of the proposed autofocusing method are illustrated in its applications to intentionally corrupted small-scene 2006 Gotcha data. The examples include the extraction of absolute phases (ranges) for selected prominent point targets. They are then used to focus the scene and determine relative target–target distances. (paper)

  12. The Analysis of Moonborne Cross Track Synthetic Aperture Radar Interferometry for Global Environment Change Monitoring

    International Nuclear Information System (INIS)

    Faced to the earth observation requirement of large scale global environment change, a SAR (Synthetic Aperture Radar) antenna system is proposed to set on Moon's surface for interferometry in this paper. With several advantages superior to low earth obit SAR, such as high space resolution, large range swath and short revisit interval, the moonborne SAR could be a potential data resource of global changes monitoring and environment change research. Due to the high stability and ease of maintenance, the novel system is competent for offering a long and continuous time series of remote sensing imagery. The Moonborne SAR system performance is discussed at the beginning. Then, the peculiarity of interferometry is analyzed in both repeat pass and single pass cases. The chief distinguishing feature which is worth to research the potentiality of repeat pass interferometry is that the revisit interval is reduced to one day in most cases, and in worst case one month. Decorrelation deriving from geometry variety is discussed in detail. It turns out that the feasibility of moonborne SAR repeat pass interferometry depends on the declination of Moon. The severity of shift effects in radar echoes increased as Moon approaches to the equatorial plane. Moreover, referring to the single pass interferometry, two antennas are assumed to set on different latitude of Moon. There is enough space on Moon to form a long baseline, which is highly related to the interferogram precision

  13. GNSS-based passive radar sensing using hybrid-aperture system

    Science.gov (United States)

    Silver, Randy; Zhang, Yan Rockee; Suarez, Hernan; Pan, Yu; Huang, Yih-Ru

    2013-05-01

    A hybrid-aperture radar system is being developed for passive, GNSS-based sensing and imaging missions. Different from previous work, the real aperture (RA) array has excellent cross-range resolution and electronic scanning capability, and synthetic aperture processing is applied for the dimension along the UAV/aircraft flight path. The hybrid aperture thus provides real-time, combined sensing capability and multiple functions. Multi-level signal synchronization and tracking is used to ensure the signal phase coherency and integrity. The advantages of covert radar sensing and reduced onboard computing complexity of this sensor are being demonstrated through experiments.

  14. Advanced Land Observing Satellite (ALOS) Phased Array Type L-Band Synthetic Aperture Radar (PALSAR) mosaic for the Kahiltna terrane, Alaska, 2007-2010

    Science.gov (United States)

    Cole, Christopher J.; Johnson, Michaela R.; Graham, Garth E.

    2015-01-01

    The U.S. Geological Survey (USGS) has initiated a multi-disciplinary study investigating the applicability of remote sensing technologies for geologic mapping and identification of prospective areas for base and precious metal deposits in remote parts of Alaska. The Kahiltna terrane in southwestern Alaska was selected for investigation because of its known mineral deposits and potential for additional mineral resources. An assortment of technologies is being investigated to aid in remote analysis of terrain, and includes imaging spectroscopy (hyperspectral remote sensing), high spatial resolution electro-optical imagery, and Synthetic Aperture Radar (SAR). However, there are significant challenges to applying imaging spectroscopy and electro-optical imagery technologies in this area because of the low solar angle for parts of the year, seasonal periods of darkness and snow cover, and the frequently cloudy weather that characterizes Alaska. Synthetic Aperture Radar (SAR) was selected because this technology does not rely on solar illumination and has all-weather capability.

  15. Polarimetric Synthetic Aperture Radar Image Classification by a Hybrid Method

    Institute of Scientific and Technical Information of China (English)

    Kamran Ullah Khan; YANG Jian

    2007-01-01

    Different methods proposed so far for accurate classification of land cover types in polarimetric synthetic aperture radar (SAR) image are data specific and no general method is available. A novel hybrid framework for this classification was developed in this work. A set of effective features derived from the coherence matrix of polarimetric SARdata was proposed.Constituents of the feature set are wavelet,texture,and nonlinear features.The proposed feature set has a strong discrimination power. A neural network was used as the classification engine in a unique way. By exploiting the speed of the conjugate gradient method and the convergence rate of the Levenberg-Marquardt method (near the optimal point), an overall speed up of the classification procedure was achieved. Principal component analysis(PCA)was used to shrink the dimension of the feature vector without sacrificing much of the classification accuracy. The proposed approach is compared with the maximum likelihood estimator (MLE)based on the complex Wishart distribution and the results show the superiority of the proposed method,with the average classification accuracy by the proposed method(95.4%)higher than that of the MLE(93.77%). Use of PCA to reduce the dimensionality of the feature vector helps reduce the memory requirements and computational cost, thereby enhancing the speed of the process.

  16. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation.

    Science.gov (United States)

    Nitti, Davide O; Bovenga, Fabio; Chiaradia, Maria T; Greco, Mario; Pinelli, Gianpaolo

    2015-07-28

    This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.

  17. Saturation Adaptive Quantizer Design for Synthetic Aperture Radar Data Compression

    Directory of Open Access Journals (Sweden)

    Navneet Agrawal

    2010-01-01

    Full Text Available The essence of remote sensing resides in the acquisition of information about remote targets for further processing. As a high resolution microwave remote sensing instrument, the Synthetic Aperture Radar (SAR has been more and more widely used. The data compression is one of the most important digital signal processing stage in remote sensing. The traditional compression algorithm is the Block adaptive quantization (BAQ due to its simplicity in implementation and results. The theoretical foundation of BAQ is the distribution of raw SAR data but in fact, the raw data is not Gaussian distributed especially when there is some saturation with the receiver. In order to overcome this drawback, the authors have studied the correlation between the mean value of the signal and its standard deviation. We also evaluated the correlation between the mean input signal and standard deviation of the output signal from the A/D. Monte-Carlo experiment shows that none of the above two correlations are optimal in the whole data set . Thus, we propose a new algorithm which gives optimum results irrespective of the degree of saturation in whole range of data. Results obtained from simulated data and real data show that the performance of new algorithm is better than conventional BAQ especially when raw data is heavily saturated. The authors have used data received from Indian satellite Chandrayaan-1 and European Space Agency (ESA in order to carry out the experimental results.

  18. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation.

    Science.gov (United States)

    Nitti, Davide O; Bovenga, Fabio; Chiaradia, Maria T; Greco, Mario; Pinelli, Gianpaolo

    2015-01-01

    This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system. PMID:26225977

  19. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation

    Directory of Open Access Journals (Sweden)

    Davide O. Nitti

    2015-07-01

    Full Text Available This study explores the potential of Synthetic Aperture Radar (SAR to aid Unmanned Aerial Vehicle (UAV navigation when Inertial Navigation System (INS measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE UAV class, which permits heavy and wide payloads (as required by SAR and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM. A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.

  20. Dual frequency Synthetic Aperture Radar (SAR) mission for monitoring our dynamic planet

    Science.gov (United States)

    Hilland, J.; Bard, S.; Key, R.; Kim, Y.; Vaze, P.; Huneycutt, B.

    2000-01-01

    Advances in spaceborne Synthetic Aperture Radar (SAR) remote sensing technology make it possible to acquire global-scale data sets that provide unique information about the Earth's continually changing surface characteristics.

  1. Integrated High-Speed Digital Optical True-Time-Delay Modules for Synthetic Aperture Radars Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Crystal Research, Inc. proposes an integrated high-speed digital optical true-time-delay module for advanced synthetic aperture radars. The unique feature of this...

  2. Feature Extraction in the North Sinai Desert Using Spaceborne Synthetic Aperture Radar: Potential Archaeological Applications

    Directory of Open Access Journals (Sweden)

    Christopher Stewart

    2016-10-01

    Full Text Available Techniques were implemented to extract anthropogenic features in the desert region of North Sinai using data from the first- and second-generation Phased Array type L-band Synthetic Aperture Radar (PALSAR-1 and 2. To obtain a synoptic view over the study area, a mosaic of average, multitemporal (De Grandi filtered PALSAR-1 σ° backscatter of North Sinai was produced. Two subset regions were selected for further analysis. The first included an area of abundant linear features of high relative backscatter in a strategic, but sparsely developed area between the Wadi Tumilat and Gebel Maghara. The second included an area of low backscatter anomaly features in a coastal sabkha around the archaeological sites of Tell el-Farama, Tell el-Mahzan, and Tell el-Kanais. Over the subset region between the Wadi Tumilat and Gebel Maghara, algorithms were developed to extract linear features and convert them to vector format to facilitate interpretation. The algorithms were based on mathematical morphology, but to distinguish apparent man-made features from sand dune ridges, several techniques were applied. The first technique took as input the average σ° backscatter and used a Digital Elevation Model (DEM derived Local Incidence Angle (LAI mask to exclude sand dune ridges. The second technique, which proved more effective, used the average interferometric coherence as input. Extracted features were compared with other available information layers and in some cases revealed partially buried roads. Over the coastal subset region a time series of PALSAR-2 spotlight data were processed. The coefficient of variation (CoV of De Grandi filtered imagery clearly revealed anomaly features of low CoV. These were compared with the results of an archaeological field walking survey carried out previously. The features generally correspond with isolated areas identified in the field survey as having a higher density of archaeological finds, and interpreted as possible

  3. DETERMINATION OF TARGET LOCATION FOR BISTATIC SYNTHETIC APERTURE RADAR BY GENETIC ALGORITHM

    OpenAIRE

    Mesut KARTAL; KARGIN, Serdar; Kent, Sedef

    2012-01-01

    In this work, the problem of determining the target locations with minimum error is studied by means of the genetic optimization method for synthetic aperture radars. The measurements at each antenna location along the synthetic aperture are being used in the genetic algorithm for error minimization. To increase the amount of data, a second receiver positioned at a different location is used and bistatic synthetic aperture is formed. The additional phase information increases the error minimi...

  4. Coastal wind field retrieval from polarimetric synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi; JIANG Xingwei; SONG Qingtao; LIN Mingsen; XIE Xuetong

    2014-01-01

    Coastal winds are strongly influenced by topology and discontinuity between land and sea surfaces. Wind assessment from remote sensing in such a complex area remains a challenge. Space-borne scatterometer does not provide any information about the coastal wind field, as the coarse spatial resolution hampers the radar backscattering. Synthetic aperture radar (SAR) with a high spatial resolution and all-weather observa-tion abilities has become one of the most important tools for ocean wind retrieval, especially in the coastal area. Conventional methods of wind field retrieval from SAR, however, require wind direction as initial infor-mation, such as the wind direction from numerical weather prediction models (NWP), which may not match the time of SAR image acquiring. Fortunately, the polarimetric observations of SAR enable independent wind retrieval from SAR images alone. In order to accurately measure coastal wind fields, this paper propos-es a new method of using co-polarization backscattering coefficients from polarimetric SAR observations up to polarimetric correlation backscattering coefficients, which are acquired from the conjugate product of co-polarization backscatter and cross-polarization backscatter. Co-polarization backscattering coefficients and polarimetric correlation backscattering coefficients are obtained form Radarsat-2 single-look complex (SLC) data.The maximum likelihood estimation is used to gain the initial results followed by the coarse spa-tial filtering and fine spatial filtering. Wind direction accuracy of the final inversion results is 10.67 with a wind speed accuracy of 0.32 m/s. Unlike previous methods, the methods described in this article utilize the SAR data itself to obtain the wind vectors and do not need external wind directional information. High spatial resolution and high accuracy are the most important features of the method described herein since the use of full polarimetric observations contains more information about the

  5. Signal Processing Algorithms for FMCW Moving Target Indicator Synthetic Aperture Radar

    NARCIS (Netherlands)

    Meta, A.; Hoogeboom, P.

    2005-01-01

    The combination of Frequency Modulated Continuous Wave (FMCW) technology and Synthetic Aperture Radar (SAR) leads to lightweight, cost-effective imaging sensors of high resolution. In FMCW SAR applications the conventional stopand- go approximation used in pulse radar algorithms cannot be considered

  6. Modified Range-Doppler Processing for FM-CW Synthetic Aperture Radar

    NARCIS (Netherlands)

    Wit, J.J.M. de; Meta, A.; Hoogeboom, P.

    2006-01-01

    The combination of compact frequency-modulated continuous-wave (FM-CW) technology and high-resolution synthetic aperture radar (SAR) processing techniques should pave the way for the development of a lightweight, cost-effective, high-resolution, airborne imaging radar. Regarding FM-CW SAR signal pro

  7. Operational Ship Monitoring System Based on Synthetic Aperture Radar Processing

    Directory of Open Access Journals (Sweden)

    Antonio Tabasco

    2009-08-01

    Full Text Available This paper presents a Ship Monitoring System (SIMONS working with Synthetic Aperture Radar (SAR images. It is able to infer ship detection and classification information, and merge the results with other input channels, such as polls from the Automatic Identification System (AIS. Two main stages can be identified, namely: SAR processing and data dissemination. The former has three independent modules, which are related to Coastline Detection (CD, Ship Detection (SD and Ship Classification (SC. The later is solved via an advanced web interface, which is compliant with the OpenSource standards fixed by the Open Geospatial Consortium (OGC. SIMONS has been designed to be a modular, unsupervised and reliable system that meets Near-Real Time (NRT delivery requirements. From data ingestion to product delivery, the processing chain is fully automatic accepting ERS and ENVISAT formats. SIMONS has been developed by GMV Aerospace, S.A. with three main goals, namely: 1 To limit the dependence on the ancillary information provided by systems such as AIS. 2 To achieve the maximum level of automatism and restrict human manipulation. 3 To limit the error sources and their propagation. Spanish authorities have validated SIMONS. The results have been satisfactory and have confirmed that the system is useful for improving decision making. For single-polarimetric images with a resolution of 30 m, SIMONS permits the location of ships larger than 40 m with a classification ratio around 50% of positive matches. These values are expected to be improved with SAR data from new sensors. In the paper, the performance of SD and SC modules is assessed by cross-check of SAR data with AIS reports.

  8. Non-breaking swell dissipation from synthethic aperture radar

    Science.gov (United States)

    Stopa, Justin; Husson, Romain; Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand

    2015-04-01

    Swells have the unique ability to propagate away from their generation region with very little attenuation. Only one study exists in the ocean wave literature that measures the decay rate by following a swell with in-situ measurements along its great circle route. More recently used space-borne synthetic aperture radar (SAR) to measure the attenuation. They estimated the dissipation rate from SAR with a limited number of cases: 11 storms with 22 total events. The present work extrapolates their technique to more events since ENVISAT has collected SAR data from 2002-2012. The dissipation rate is then determined in a two step process. First swell sources are identified from density maps of back-propagated waves at their group velocity along great circles. Next a "point-source" model is assumed and the waves from all directions and frequencies are propagated forward to find matching SAR observations. Relatively small directional bins are used to group observations creating transects from a given swell event. This ensemble of tracks is the basic dataset used to calculate a more statistically robust measure of the dissipation rate. Individual tracks and the swell behavior are explored through this dataset. Our results are in agreement with previous findings and it is verified that swells are very persistent with e-folding scales larger than 20,000 km and they behave nonlinearly as a function of wave frequency. The results are discussed in terms of their implications in spectral wave models as well as identify limitations of the remotely sensed wave spectra. The wind's role on the dissipation rate cannot be determined from this analysis stressing the need for concurrent wind and wave observations.

  9. NASA-ISRO synthetic aperture radar: science and applications

    Science.gov (United States)

    Kumar, Raj; Rosen, Paul; Misra, Tapan

    2016-05-01

    NASA-ISRO Synthetic Aperture Radar (NISAR), a novel SAR concept will be utilized to image wide swath at high resolution of stripmap SAR. It will have observations in L- and S-bands to understand highly spatial and temporally complex processes such as ecosystem disturbances, ice sheet changes, and natural hazards including earthquakes, tsunamis, volcanoes, and landslides. NISAR with several advanced features such as 12 days interferometric orbit, achievement of high resolution and wide swath images through SweepSAR technology and simultaneous data acquisition in dual frequency would support a host of applications. The primary objectives of NISAR are to monitor ecosystems including monitoring changes in ecosystem structure and biomass estimation, carbon flux monitoring; mangroves and wetlands characterization; alpine forest characterization and delineation of tree-line ecotone, land surface deformation including measurement of deformation due to co-seismic and inter-seismic activities; landslides; land subsidence and volcanic deformation, cryosphere studies including measurements of dynamics of polar ice sheet, ice discharge to the ocean, Himalayan snow and glacier dynamics, deep and coastal ocean studies including retrieval of ocean parameters, mapping of coastal erosion and shore-line change; demarcation of high tide line (HTL) and low tide line (LTL) for coastal regulation zones (CRZ) mapping, geological studies including mapping of structural and lithological features; lineaments and paleo-channels; geo-morphological mapping, natural disaster response including mapping and monitoring of floods, forest fires, oil spills, earthquake damage and monitoring of extreme weather events such as cyclones. In addition to the above, NISAR would support various other applications such as enhanced crop monitoring, soil moisture estimation, urban area development, weather and hydrological forecasting.

  10. Synthetic Aperture Radar Data Processing on an FPGA Multi-Core System

    DEFF Research Database (Denmark)

    Schleuniger, Pascal; Kusk, Anders; Dall, Jørgen;

    2013-01-01

    Synthetic aperture radar, SAR, is a high resolution imaging radar. The direct back-projection algorithm allows for a precise SAR output image reconstruction and can compensate for deviations in the flight track of airborne radars. Often graphic processing units, GPUs are used for data processing...... that the system provides real-time processing of a SAR application that maps a 3000m wide area with a resolution of 2x2 meters....

  11. Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

    OpenAIRE

    Zygmuntowska, M.; Khvorostovsky, K.; V. Helm; S. Sandven

    2013-01-01

    Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300m along track. In this study, airborne Ku-band radar altimeter data over different ...

  12. High Resolution Ionospheric Mapping Using Spaceborne Synthetic Aperture Radars

    Science.gov (United States)

    Meyer, F. J.; Chotoo, K.; Roth, A. P.

    2012-12-01

    Spaceborne Synthetic Aperture Radars (SARs) are imaging radar systems that utilize the Doppler history of signals acquired during satellite flyby to produce high resolution images of the Earth. With modern sensors, operating at frequencies between about 1 GHz (L-band) and 10 GHz (X-band), radar images with resolutions in the meter to sub-meter range can be produced. The presence of the ionosphere is significantly affecting the propagation properties of the microwave signals transmitted by these systems, causing distortions of signal polarization and phase. These distortions can lead to a wide range of imaging artifacts including image range shifts, interferometric phase biases, loss of image focus, change of image geometry, and Faraday rotation. While these artifacts are particularly pronounced at L-band, they are still observable in data acquired at C- or even X-band. In recent years, a wealth of methods for measuring and correcting ionospheric influence were developed. These methods are self-calibration procedures that measure ionosphere-induced distortions to infer the two-dimensional TEC maps that affected the data. These TEC maps are then removed from the data to produce high performance SAR images. Besides being effective in correcting SAR observations, these self-calibration methods are producing high quality TEC information with sub-TECU sensitivity and sub-kilometer spatial resolution. The intent of this paper is to utilize SAR-derived ionospheric information and make the case for SAR as a data source for ionospheric research. After a short summary of ionosphere-induced distortions, the concept of TEC estimation from SAR is introduced. Here, the current state-of-the-art of ionospheric TEC estimation is presented, including Faraday rotation-based, interferometric, correlation-based, and autofocus-based techniques. For every approach, performance numbers are given that quantify the achievable TEC estimation accuracy as a function of system parameters, scene

  13. A despeckle filter for the Cassini synthetic aperture radar images of Titan's surface

    Science.gov (United States)

    Bratsolis, Emmanuel; Bampasidis, Georgios; Solomonidou, Anezina; Coustenis, Athena

    2012-02-01

    Cassini synthetic aperture radar (SAR) images of Titan, the largest satellite of Saturn, reveal surface features with shapes ranging from quasi-circular to more complex ones, interpreted as liquid hydrocarbon deposits assembled in the form of lakes or seas. One of the major problems hampering the derivation of meaningful texture information from SAR imagery is the speckle noise. It overlays real structures and causes gray value variations even in homogeneous parts of the image. We propose a filtering technique which can be applied to obtain restored SAR images. Our technique is based on probabilistic methods and regards an image as a random element drawn from a prespecified set of possible images. The despeckle filter can be used as an intermediate step for the extraction of regions of interest, corresponding to structured units in a given area or distinct objects of interest, such as lake-like features on Titan. This tool can therefore be used, among other, to study seasonal surficial changes of Titan's polar regions. In this study we also present a segmentation technique that allows us to separate the lakes from the local background.

  14. Autofocusing circular synthetic aperture sonar imagery using phase corrections modeled as generalized cones.

    Science.gov (United States)

    Marston, Timothy M; Kennedy, Jermaine L; Marston, Philip L

    2014-08-01

    Circular synthetic aperture sonar (CSAS) is a coherent aperture synthesis technique that utilizes backscattered acoustic information from an encircled scene to generate information rich, high-resolution imagery. The aperture length required for image synthesis is much longer than in its linear synthetic aperture sonar counterpart and can result in challenging phase delay and navigation estimation constraints. Residual uncorrected phase errors manifest as focus aberrations in reconstructed CSAS imagery. This paper demonstrates that phase error in image patches can be approximated as an aspect variant linear phase shift representable as a generalized cone in wave-number space. If the geometry of the generalized cone is known, it can be applied as the spectral phase of an inverse filter for aberration correction. A method is derived for reconstructing the error cone geometry from independent estimates of its local curvatures, which are found via a series of one-dimensional line searches that maximize the focus of CSAS sub-aperture images. This approach is applied to real and simulated CSAS data containing aperture distortions, and the results successfully demonstrate estimation and correction of the underlying focus aberrations.

  15. NOAA high resolution sea surface winds data from Synthetic Aperture Radar (SAR) on the RADARSAT-2 satellite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Synthetic Aperture Radar (SAR)-derived high resolution wind products are calculated from high resolution SAR images of normalized radar cross section (NRCS) of the...

  16. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    Science.gov (United States)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  17. The DESDynI Synthetic Aperture Radar Array-Fed Reflector Antenna

    Science.gov (United States)

    Chamberlain, Neil; Ghaemi, Hirad; Giersch, Louis; Harcke, Leif; Hodges, Richard; Hoffman, James; Johnson, William; Jordan, Rolando; Khayatian, Behrouz; Rosen, Paul; Sadowy, Gregory; Shaffer, Scott; Shen, Yuhsyen; Veilleux, Louise; Wu, Patrick

    2010-01-01

    DESDynI is a mission being developed by NASA with radar and lidar instruments for Earth-orbit remote sensing. This paper focuses on the design of a largeaperture antenna for the radar instrument. The antenna comprises a deployable reflector antenna and an active switched array of patch elements fed by transmit/ receive modules. The antenna and radar architecture facilitates a new mode of synthetic aperture radar imaging called 'SweepSAR'. A system-level description of the antenna is provided, along with predictions of antenna performance.

  18. Ultrawideband-Ultrawidebeam Synthetic Aperture Radar – Signal Processing and Applications

    OpenAIRE

    Vu, Viet Thuy

    2011-01-01

    This dissertation presents practical issues in Ultrawideband – Ultrawidebeam (UWB) Synthetic Aperture Radar (SAR) signal processing and crucial applications developed on UWB SAR. In the context of this dissertation, UWB SAR refers to the SAR systems utilizing large fractional bandwidth signals and synthesizing long apertures associated with wide antenna beamwidths. On one hand, such specific systems give us opportunities to develop unique applications. One the other hand, signal processing fo...

  19. Concept Development for Advanced Spaceborne Synthetic Aperture Radar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The effort will focus on P-Band and L-band polarimetric radar architectures that employ advanced and innovative techniques to increase the science value of the...

  20. a Fuzzy Logic-Based Approach for the Detection of Flooded Vegetation by Means of Synthetic Aperture Radar Data

    Science.gov (United States)

    Tsyganskaya, V.; Martinis, S.; Twele, A.; Cao, W.; Schmitt, A.; Marzahn, P.; Ludwig, R.

    2016-06-01

    In this paper an algorithm designed to map flooded vegetation from synthetic aperture radar (SAR) imagery is introduced. The approach is based on fuzzy logic which enables to deal with the ambiguity of SAR data and to integrate multiple ancillary data containing topographical information, simple hydraulic considerations and land cover information. This allows the exclusion of image elements with a backscatter value similar to flooded vegetation, to significantly reduce misclassification errors. The flooded vegetation mapping procedure is tested on a flood event that occurred in Germany over parts of the Saale catchment on January 2011 using a time series of high resolution TerraSAR-X data covering the time interval from 2009 to 2015. The results show that the analysis of multi-temporal X-band data combined with ancillary data using a fuzzy logic-based approach permits the detection of flooded vegetation areas.

  1. A FUZZY LOGIC-BASED APPROACH FOR THE DETECTION OF FLOODED VEGETATION BY MEANS OF SYNTHETIC APERTURE RADAR DATA

    Directory of Open Access Journals (Sweden)

    V. Tsyganskaya

    2016-06-01

    Full Text Available In this paper an algorithm designed to map flooded vegetation from synthetic aperture radar (SAR imagery is introduced. The approach is based on fuzzy logic which enables to deal with the ambiguity of SAR data and to integrate multiple ancillary data containing topographical information, simple hydraulic considerations and land cover information. This allows the exclusion of image elements with a backscatter value similar to flooded vegetation, to significantly reduce misclassification errors. The flooded vegetation mapping procedure is tested on a flood event that occurred in Germany over parts of the Saale catchment on January 2011 using a time series of high resolution TerraSAR-X data covering the time interval from 2009 to 2015. The results show that the analysis of multi-temporal X-band data combined with ancillary data using a fuzzy logic-based approach permits the detection of flooded vegetation areas.

  2. Nonlinear filtering for tracking large objects in radar imagery

    Science.gov (United States)

    Greenewald, John H.; Musick, Stanton H.

    2005-05-01

    Detecting and tracking a moving ground target in radar imagery is a challenge intensified by clutter, sensor anomalies, and the substantial signature variations that occur when a target's aspect angle changes rapidly. In its GMTI mode, a radar produces range-Doppler images that contain both kinematic reports and shape features. An HRR signature, when formed as the Fourier transform of the range-Doppler image across its Doppler dimension, becomes a derived measurement and an alternative source of identity information. Although HRR signatures can vary enormously with even small changes in target aspect, such signatures were vital for associating kinematic reports to tracks in this work. This development started with video phase history (VPH) data recorded from a live experiment involving a GMTI radar viewing a single moving target. Since the target could appear anywhere in the range-Doppler image derived from the VPH data, the goal was to localize it in a small range-Doppler "chip" that could be extracted and used in subsequent research. Although the clutter in any given VPH frame generally caused false chips to be formed in the full range-Doppler image, at most one chip contained the target. The most effective approach for creating any chip is to ensure that the object is present in the return from each pulse that contributes to that chip, and to correct any phase distortions arising from range gate changes. Processing constraints dictated that the algorithm for target chip extraction be coded in MATLAB with a time budget of a few seconds per frame. Furthermore, templates and shape models to describe the target were prohibited. This paper describes the nonlinear filtering approach used to reason over multiple frames of VPH data. This nonlinear approach automatically detects and segments potential targets in the range-Doppler imagery, and then extracts kinematic and shape features that are tracked over multiple data frames to ensure that the real target is in the

  3. Stereoscopic Height Estimation from Multiple Aspect Synthetic Aperture Radar Images; TOPICAL

    International Nuclear Information System (INIS)

    A Synthetic Aperture Radar (SAR) image is a two-dimensional projection of the radar reflectivity from a 3-dimensional object or scene. Stereoscopic SAR employs two SAR images from distinct flight paths that can be processed together to extract information of the third collapsed dimension (typically height) with some degree of accuracy. However, more than two SAR images of the same scene can similarly be processed to further improve height accuracy, and hence 3-dimensional position accuracy. This report shows how

  4. Investigation on Beamspace Multiple-Input Multiple-Output Synthetic Aperture Radar Data Imaging

    OpenAIRE

    Hongbo Mo; Wei Xu; Zhimin Zeng

    2016-01-01

    The multiple-input multiple-output (MIMO) technique can improve the high-resolution wide-swath imaging capacity of synthetic aperture radar (SAR) systems. Beamspace MIMO-SAR utilizes multiple subpulses transmitted with different time delays by different transmit beams to obtain more spatial diversities based on the relationship between the time delay and the elevation angle in the side-looking radar imaging geometry. This paper presents a beamspace MIMO-SAR imaging approach, which takes advan...

  5. Correction and Characterization of Radio Frequency Interference Signatures in L-band Synthetic Aperture Radar Data

    OpenAIRE

    Meyer, Franz; Nicoll, Jeremy; Doulgeris, Anthony Paul

    2013-01-01

    Radio frequency interference (RFI) is a known issue in low-frequency radar remote sensing. In synthetic aperture radar (SAR) image processing, RFI can cause severe degradation of image quality, distortion of polarimetric signatures, and an increase of the SAR phase noise level. To address this issue, a processing system was developed that is capable of reliably detecting, characterizing, and mitigating RFI signatures in SAR observations. In addition to being the basis for image correction, th...

  6. Statistically normalized coherent change detection for synthetic aperture sonar imagery

    Science.gov (United States)

    G-Michael, Tesfaye; Tucker, J. D.; Roberts, Rodney G.

    2016-05-01

    Coherent Change Detection (CCD) is a process of highlighting an area of activity in scenes (seafloor) under survey and generated from pairs of synthetic aperture sonar (SAS) images of approximately the same location observed at two different time instances. The problem of CCD and subsequent anomaly feature extraction/detection is complicated due to several factors such as the presence of random speckle pattern in the images, changing environmental conditions, and platform instabilities. These complications make the detection of weak target activities even more difficult. Typically, the degree of similarity between two images measured at each pixel locations is the coherence between the complex pixel values in the two images. Higher coherence indicates little change in the scene represented by the pixel and lower coherence indicates change activity in the scene. Such coherence estimation scheme based on the pixel intensity correlation is an ad-hoc procedure where the effectiveness of the change detection is determined by the choice of threshold which can lead to high false alarm rates. In this paper, we propose a novel approach for anomalous change pattern detection using the statistical normalized coherence and multi-pass coherent processing. This method may be used to mitigate shadows by reducing the false alarms resulting in the coherent map due to speckles and shadows. Test results of the proposed methods on a data set of SAS images will be presented, illustrating the effectiveness of the normalized coherence in terms statistics from multi-pass survey of the same scene.

  7. Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

    Science.gov (United States)

    Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

    2016-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of

  8. Advances in Detection and Classification of Underwater Targets using Synthetic Aperture Sonar Imagery

    OpenAIRE

    Fei, Tai

    2015-01-01

    In this PhD thesis, the problem of underwater mine detection and classification using synthetic aperture sonar (SAS) imagery is considered. The automatic detection and automatic classification (ADAC) system is applied to images obtained by SAS systems. The ADAC system contains four steps, namely mine-like object (MLO) detection, image segmentation, feature extraction, and mine type classification. This thesis focuses on the last three steps. In the mine-like object detectio...

  9. Synthetic aperture radar interferometry coherence analysis over Katmai volcano group, Alaska

    Science.gov (United States)

    Lu, Zhiming; Freymueller, J.T.

    1998-01-01

    The feasibility of measuring volcanic deformation or monitoring deformation of active volcanoes using space-borne synthetic aperture radar (SAR) interferometry depends on the ability to maintain phase coherence over appropriate time intervals. Using ERS 1 C band (?? = 5.66 cm) SAR imagery, we studied the seasonal and temporal changes of the interferometric SAR coherence for fresh lava, weathered lava, tephra with weak water reworking, tephra with strong water reworking, and fluvial deposits representing the range of typical volcanic surface materials in the Katmai volcano group, Alaska. For interferograms based on two passes with 35 days separation taken during the same summer season, we found that coherence increases after early June, reaches a peak between the middle of July and the middle of September, and finally decreases until the middle of November when coherence is completely lost for all five sites. Fresh lava has the highest coherence, followed by either weathered lava or fluvial deposits. These surfaces maintain relatively high levels of coherence for periods up to the length of the summer season. Coherence degrades more rapidly with time for surfaces covered with tephra. For images taken in different summers, only the lavas maintained coherence well enough to provide useful interferometric images, but we found only a small reduction in coherence after the first year for surfaces with lava. Measurement of volcanic deformation is possible using summer images spaced a few years apart, as long as the surface is dominated by lavas. Our studies suggest that in order to make volcanic monitoring feasible along the Aleutian arc or other regions with similar climatic conditions, observation intervals of the satellite with C band SAR should be at least every month from July through September, every week during the late spring/early summer or late fall, and every 2-3 days during the winter. Copyright 1998 by the American Geophysical Union.

  10. Wavefront curvature limitations and compensation to polar format processing for synthetic aperture radar images.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-01-01

    Limitations on focused scene size for the Polar Format Algorithm (PFA) for Synthetic Aperture Radar (SAR) image formation are derived. A post processing filtering technique for compensating the spatially variant blurring in the image is examined. Modifications to this technique to enhance its robustness are proposed.

  11. Basics of Polar-Format algorithm for processing Synthetic Aperture Radar images.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2012-05-01

    The purpose of this report is to provide a background to Synthetic Aperture Radar (SAR) image formation using the Polar Format (PFA) processing algorithm. This is meant to be an aid to those tasked to implement real-time image formation using the Polar Format processing algorithm.

  12. Mapping Offshore Winds Around Iceland Using Satellite Synthetic Aperture Radar and Mesoscale Model Simulations

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Nawri, Nikolai;

    2015-01-01

    The offshore wind climate in Iceland is examined based on satellite synthetic aperture radar (SAR), coastal meteorological station measurements, and results from two atmospheric model data sets, HARMONIE and NORA10. The offshore winds in Iceland are highly influenced by the rugged coastline. Lee...

  13. Complex Wishart distribution based analysis of polarimetric synthetic aperture radar data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Skriver, Henning; Conradsen, Knut

    2007-01-01

    Multi-look, polarimetric synthetic aperture radar (SAR) data are often worked with in the so-called covariance matrix representation. For each pixel this representation gives a 3x3 Hermitian, positive definite matrix which follows a complex Wishart distribution. Based on this distribution a test...

  14. P-SAR: An Advanced Miniature Synthetic Aperture Radar for Forestry Applications. Preliminary Design

    NARCIS (Netherlands)

    Figueras i Ventura, J.; Hoogeboom, P.

    2005-01-01

    A preliminary study of the design of a small, low cost, Pband airborne, polarimetric synthetic aperture radar (SAR) is presented. The design was requested by the Wageningen University and the Borneo Orangutan Survival Foundation (BOS) to carry out forest biomass monitoring in Indonesia. The requirem

  15. Design of a Small, Low Cost, P-Band Airborne Polarimetric Synthetic Aperture Radar

    NARCIS (Netherlands)

    Figueras i Ventura, J.; Hoogeboom, P.

    2004-01-01

    A preliminary study of the design of a small, low cost, P-band airborne, polarimetric Synthetic Aperture Radar desired by the Wageningen University and the Borneo Orangutan Survival Foundation (BOS) to carry out forest biomass monitoring in Indonesia is presented. The requirements of the application

  16. Three-dimensional subsurface imaging Synthetic Aperture Radar

    International Nuclear Information System (INIS)

    This report describes the development of a system known as 3-D SISAR. This system consists of a ground penetrating radar with software algorithms designed for the detection, location, and identification of buried objects in the underground hazardous waste environments at DOE storage sites

  17. Three-dimensional subsurface imaging Synthetic Aperture Radar

    Energy Technology Data Exchange (ETDEWEB)

    Wuenschel, E. [Mirage Systems, Inc., Sunnyvale, CA (United States)

    1995-10-01

    This report describes the development of a system known as 3-D SISAR. This system consists of a ground penetrating radar with software algorithms designed for the detection, location, and identification of buried objects in the underground hazardous waste environments at DOE storage sites.

  18. Three-dimensional, subsurface imaging synthetic aperture radar

    International Nuclear Information System (INIS)

    The objective of this applied research and devolpment project is to develop a system known as 3-D SISAR. This sytem consists of a gound penetrating radar with software algorithms designed for detection, location, and identification of buried objects in the underground hazardous waste environments found at US DOE storage sites. Three-dimensional maps can assist the development of remdiation strategies and characterization of the digface during remediation. The system should also be useful for monitoring hydrocarbon-based contaminant migration after remediation. 5 figs

  19. Spotlight-Mode Synthetic Aperture Radar Processing for High-Resolution Lunar Mapping

    Science.gov (United States)

    Harcke, Leif; Weintraub, Lawrence; Yun, Sang-Ho; Dickinson, Richard; Gurrola, Eric; Hensley, Scott; Marechal, Nicholas

    2010-01-01

    During the 2008-2009 year, the Goldstone Solar System Radar was upgraded to support radar mapping of the lunar poles at 4 m resolution. The finer resolution of the new system and the accompanying migration through resolution cells called for spotlight, rather than delay-Doppler, imaging techniques. A new pre-processing system supports fast-time Doppler removal and motion compensation to a point. Two spotlight imaging techniques which compensate for phase errors due to i) out of focus-plane motion of the radar and ii) local topography, have been implemented and tested. One is based on the polar format algorithm followed by a unique autofocus technique, the other is a full bistatic time-domain backprojection technique. The processing system yields imagery of the specified resolution. Products enabled by this new system include topographic mapping through radar interferometry, and change detection techniques (amplitude and coherent change) for geolocation of the NASA LCROSS mission impact site.

  20. Tracking lava flow emplacement on the east rift zone of Kilauea, Hawai’i with synthetic aperture radar (SAR) coherence

    Science.gov (United States)

    Dietterich, Hannah R.; Poland, Michael P.; Schmidt, David; Cashman, Katharine V.; Sherrod, David R.; Espinosa, Arkin Tapia

    2012-01-01

    Lava flow mapping is both an essential component of volcano monitoring and a valuable tool for investigating lava flow behavior. Although maps are traditionally created through field surveys, remote sensing allows an extraordinary view of active lava flows while avoiding the difficulties of mapping on location. Synthetic aperture radar (SAR) imagery, in particular, can detect changes in a flow field by comparing two images collected at different times with SAR coherence. New lava flows radically alter the scattering properties of the surface, making the radar signal decorrelated in SAR coherence images. We describe a new technique, SAR Coherence Mapping (SCM), to map lava flows automatically from coherence images independent of look angle or satellite path. We use this approach to map lava flow emplacement during the Pu‘u ‘Ō‘ō-Kupaianaha eruption at Kīlauea, Hawai‘i. The resulting flow maps correspond well with field mapping and better resolve the internal structure of surface flows, as well as the locations of active flow paths. However, the SCM technique is only moderately successful at mapping flows that enter vegetation, which is also often decorrelated between successive SAR images. Along with measurements of planform morphology, we are able to show that the length of time a flow stays decorrelated after initial emplacement is linearly related to the flow thickness. Finally, we use interferograms obtained after flow surfaces become correlated to show that persistent decorrelation is caused by post-emplacement flow subsidence.

  1. Soil Moisture Estimation in South-Eastern New Mexico Using High Resolution Synthetic Aperture Radar (SAR Data

    Directory of Open Access Journals (Sweden)

    A.K.M. Azad Hossain

    2016-01-01

    Full Text Available Soil moisture monitoring and characterization of the spatial and temporal variability of this hydrologic parameter at scales from small catchments to large river basins continues to receive much attention, reflecting its critical role in subsurface-land surface-atmospheric interactions and its importance to drought analysis, irrigation planning, crop yield forecasting, flood protection, and forest fire prevention. Synthetic Aperture Radar (SAR data acquired at different spatial resolutions have been successfully used to estimate soil moisture in different semi-arid areas of the world for many years. This research investigated the potential of linear multiple regressions and Artificial Neural Networks (ANN based models that incorporate different geophysical variables with Radarsat 1 SAR fine imagery and concurrently measured soil moisture measurements to estimate surface soil moisture in Nash Draw, NM. An artificial neural network based model with vegetation density, soil type, and elevation data as input in addition to radar backscatter values was found suitable to estimate surface soil moisture in this area with reasonable accuracy. This model was applied to a time series of SAR data acquired in 2006 to produce soil moisture data covering a normal wet season in the study site.

  2. A Dual-polarized Microstrip Subarray Antenna for an Inflatable L-band Synthetic Aperture Radar

    Science.gov (United States)

    Zawadzki, Mark; Huang, John

    1999-01-01

    Inflatable technology has been identified as a potential solution to the problem of achieving small mass, high packaging efficiency, and reliable deployment for future NASA spaceborne synthetic aperture radar (SAR) antennas. Presently, there exists a requirement for a dual-polarized L-band SAR antenna with an aperture size of 10m x 3m, a center frequency of 1.25GHz, a bandwidth of 80MHz, electronic beam scanning, and a mass of less than 100kg. The work presented below is part of the ongoing effort to develop such an inflatable antenna array.

  3. Detection performance analysis for MIMO radar with distributed apertures in Gaussian colored noise

    Institute of Scientific and Technical Information of China (English)

    GUAN Jian; HUANG Yong

    2009-01-01

    This paper establishes the classic linear model of signal of the MIMO radar system with distributed apertures.Based on this model,the design principle and detection performance of MIMO radar detector is investigated under conditions of Gaussian colored noise and partially correlated observation channels.First,the research on design principle of detector shows that the clutter suppression and matched filtering can be independently implemented at each receiving aperture,which greatly reduces the difficulty in implementation of these detectors.Based on these results,a Max detector is proposed for the case where partial channels are disabled due to strong noise and stealth techniques.The second part is the performance analysis of detector.The Fishier divergence coefficient and the statistical equivalent decomposition of limit statistics are used to theoretically analyze the detection performance of AMF detector,and then the analytical expressions of the detection performance of the AMF detector is derived.Analysis results show that both the colored nature of noise and the correlation among observation channels can reduce the capability of spatial diversity of the MIMO radar system,change the target RCSs among observation channels from quick fluctuation to slow fluctuation,and degenerate the detection performance of this radar system into that of the phased array radar system at high signal-to-noise ratio.

  4. Synthetic Aperture Radar: The NCCS Enables Search and Rescue

    Science.gov (United States)

    2002-01-01

    For as long as planes have gone down, dedicated men and women have used ever-improving technologies to aid their search for survivors. Nearly 2,000 general aviation crashes occur each year in U.S.-and many, like the Montana incident, occur without witnesses. On average, every day in the U.S. one airplane is reported missing. The Air Force Rescue Coordination Center (AFRCC) organizes search missions for about 100 aircraft each year. Some of these are not found before the searches called off, and are discovered only by chance long after the crash. In some cases, the crash site is never found. NASA Search and Rescue Mission is using NCCS rescues to develop tools for processing radar data that can help these effort

  5. Evaluation Digital Elevation Model Generated by Synthetic Aperture Radar Data

    Science.gov (United States)

    Makineci, H. B.; Karabörk, H.

    2016-06-01

    Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS). Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry) and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data) and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

  6. EVALUATION DIGITAL ELEVATION MODEL GENERATED BY SYNTHETIC APERTURE RADAR DATA

    Directory of Open Access Journals (Sweden)

    H. B. Makineci

    2016-06-01

    Full Text Available Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS. Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

  7. IFP V4.0:a polar-reformatting image formation processor for synthetic aperture radar.

    Energy Technology Data Exchange (ETDEWEB)

    Eichel, Paul H.

    2005-09-01

    IFP V4.0 is the fourth generation of an extraordinarily powerful and flexible image formation processor for spotlight mode synthetic aperture radar. It has been successfully utilized in processing phase histories from numerous radars and has been instrumental in the development of many new capabilities for spotlight mode SAR. This document provides a brief history of the development of IFP, a full exposition of the signal processing steps involved, and a short user's manual for the software implementing this latest iteration.

  8. Coherent Performance Analysis of the HJ-1-C Synthetic Aperture Radar

    OpenAIRE

    Li Hai-ying; Zhang Shan-shan; Li Shi-qiang; Zhang Hua-chun

    2014-01-01

    Synthetic Aperture Radar (SAR) is a coherent imaging radar. Hence, coherence is critical in SAR imaging. In a coherent system, several sources can degrade performance. Based on the HJ-1-C SAR system implementation and sensor characteristics, this study evaluates the effect of frequency stability and pulse-to-pulse timing jitter on the SAR coherent performance. A stable crystal oscillator with short-term stability of 10×1.0−10 / 5 ms is used to generate the reference frequency by using a direc...

  9. Study on the Algorithm to Retrieve Precipitation with X-Band Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    XIE Yanan; HUAN Jianping; TAO Yang

    2010-01-01

    In order to obtain the global precipitation distribution data,this paper investigates the precipitation distribution model,the normalized radar cross-section model,and the retrieval algorithm with X-band synthetic aperture radar(X-SAR).A new retrieval algorithm based on the surface-scattering reference attenuation is developed to retrieve the rain rate above the ground surface.This new algorithm needs no statistical work load and has more extensive applications.Calculations using the new algorithm for three cases verify that the rainfall is retrieved with high precision,which proves the capability of the algorithm.

  10. SIMULATION STUDY OF IMAGING OF UNDERWATER BOTTOM TOPOGRAPHY BY SYNTHETIC APERTURE RADAR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Interaction between current and underwater bottom topography modulates roughness of the sea surface, which in turn yields variation of the radar scattering echo. By using the mechanism, this paper presents a simulation model for Synthetic Aperture Radar (SAR) imaging of underwater bottom topography. The numerical simulations experiments were made using the Princeton Ocean Model (POM) and analytical expression theory of SAR Image in Mischief sea area. It is concluded that the SAR image is better visual when water depth of underwater bottom topography is shallow or gradient of underwater bottom topography is high.

  11. Swell dissipation from 10 years of Envisat advanced synthetic aperture radar in wave mode

    Science.gov (United States)

    Stopa, Justin E.; Ardhuin, Fabrice; Husson, Romain; Jiang, Haoyu; Chapron, Bertrand; Collard, Fabrice

    2016-04-01

    Swells are found in all oceans and strongly influence the wave climate and air-sea processes. The poorly known swell dissipation is the largest source of error in wave forecasts and hindcasts. We use synthetic aperture radar data to identify swell sources and trajectories, allowing a statistically significant estimation of swell dissipation. We mined the entire Envisat mission 2003-2012 to find suitable storms with swells (13 analysis reveals that swell dissipation weakly correlates with the wave steepness, wind speed, orbital wave velocity, and the relative direction of wind and waves. Although several negative dissipation rates are found, there are uncertainties in the synthetic aperture radar-derived swell heights and dissipation rates. An acceptable range of the swell dissipation rate is -0.1 to 6 × 10-7 m-1 with a median of 1 × 10-7 m-1.

  12. Remote sensing satellite formation for bistatic synthetic aperture radar observation

    Science.gov (United States)

    D'Errico, Marco; Moccia, Antonio

    2001-12-01

    In recent years the Italian Space Agency has been proceeding to the definition and launch of small missions. In this ambit, the BISSAT mission was proposed and selected along with five other missions for a competitive Phase A study. BISSAT mission concept consists in flying a passive SAR on board a small satellite, which observes the area illuminated by an active SAR, operating on an already existing large platform. Several scientific applications of bistatic measurements can be envisaged: improvement of image classification and pattern recognition, derivation of medium-resolution digital elevation models, velocity measurements, measurements of sea-wave spectra. BISSAT payload is developed on the basis of the X-band SAR of the COSMO/SkyMed mission, while BISSAT bus is based on an upgrade of MITA. Orbit design has been performed, leading to the same orbit parameters apart from the ascending node right ascension (5.24 degree(s) shift) and the time of the passage on the ascending node (1.17s shift). A minimum distance at the passage of the orbit crossing point of about 42 km (5.7s) is computed. To maintain adequate swath overlap along the orbit, attitude maneuver or antenna electronic steering must be envisaged and traded-off taking into account radar performance and cost of hardware upgrade.

  13. SYNTHETIC APERTURE RADAR (SAR) BASED CLASSIFIERS FOR LAND APPLICATIONS IN GERMANY

    OpenAIRE

    Suresh, G.; Gehrke, R.; T. Wiatr; Hovenbitzer, M.

    2016-01-01

    Land cover information is essential for urban planning and for land cover change monitoring. This paper presents an overview of the work conducted at the Federal Agency for Cartography and Geodesy (BKG) with respect to Synthetic Aperture Radar (SAR) based land cover classification. Two land cover classification approaches using SAR images are reported in this paper. The first method involves a rule-based classification using only SAR backscatter intensity while the other method involves super...

  14. Sequential Ensembles Tolerant to Synthetic Aperture Radar (SAR) Soil Moisture Retrieval Errors

    OpenAIRE

    Ju Hyoung Lee

    2016-01-01

    Due to complicated and undefined systematic errors in satellite observation, data assimilation integrating model states with satellite observations is more complicated than field measurements-based data assimilation at a local scale. In the case of Synthetic Aperture Radar (SAR) soil moisture, the systematic errors arising from uncertainties in roughness conditions are significant and unavoidable, but current satellite bias correction methods do not resolve the problems very well. Thus, apart...

  15. Change Detection in Synthetic Aperture Radar Images Using a Multiscale-Driven Approach

    OpenAIRE

    Olaniyi A. Ajadi; Franz J. Meyer; Peter W. Webley

    2016-01-01

    Despite the significant progress that was achieved throughout the recent years, to this day, automatic change detection and classification from synthetic aperture radar (SAR) images remains a difficult task. This is, in large part, due to (a) the high level of speckle noise that is inherent to SAR data; (b) the complex scattering response of SAR even for rather homogeneous targets; (c) the low temporal sampling that is often achieved with SAR systems, since sequential images do not always hav...

  16. Swell dissipation from 10 years of Envisat advanced synthetic aperture radar in wave mode

    OpenAIRE

    Stopa, J. E.; Ardhuin, Fabrice; Husson, R.; Jiang, H. Y.; Chapron, B.; Collard, F.

    2016-01-01

    Swells are found in all oceans and strongly influence the wave climate and air-sea processes. The poorly known swell dissipation is the largest source of error in wave forecasts and hindcasts. We use synthetic aperture radar data to identify swell sources and trajectories, allowing a statistically significant estimation of swell dissipation. We mined the entire Envisat mission 2003-2012 to find suitable storms with swells (13 < T< 18 s) that are observed several times along their propagation....

  17. a Robust Change Detector for Multilook Polarimetric Synthetic Aperture Radar Data

    Science.gov (United States)

    Ghanbari; Akbari; Abkar; Sahebi; Liu

    2014-10-01

    In this paper, we propose a robust unsupervised change detection algorithm for multilook polarimetric synthetic aperture radar (PolSAR) data. The Hotelling-Lawley trace (HLT) statistic is used as a test statistic to measure the similarity of two covariance matrices. The generalized Kittler and Illingworth (K&I) minimum-error thresholding algorithm is then applied on the test statistic image to accurately discriminates changed and unchanged areas. The algorithm, tested on real PolSAR images, provides satisfactory results.

  18. Experimental investigation of real aperture synthetically organised radar for breast cancer detection

    OpenAIRE

    Craddock, IJ; Nilavalan, R.; Leendertz, JA; Preece, AW; Benjamin, R.

    2005-01-01

    Breast cancer is the most common cancer in woman, and early detection increases the likelihood of successful treatment and long-term survival screen film mammography is currently the most effective method for detecting breast tumours, however this technique suffers from relatively high false negative and positive detection rates, and it involves uncomfortable compression of the breast. This paper presents the experimental investigation of real aperture synthetically organised radar for breast...

  19. Determining the mixing of oil and sea water using polarimetric synthetic aperture radar

    OpenAIRE

    Minchew, Brent

    2012-01-01

    Knowledge of the characteristics of spilled oil in the ocean is important for cleanup operations, predictions of the impact on wildlife, and studies of the nature of the ocean surface and currents. Herein I discuss a method for evaluating the characteristics of oil in a marine environment using synthetic aperture radar (SAR) and present a new, simple classification, called the oil/water mixing index (Mdex), to quickly assess the results. I link the Mdex results to the Bonn Agreement for...

  20. A COMPARISON OF SOME ELECTRONIC COUNTERMEASURES ON INVERSE SYNTHETIC APERTURE RADAR (ISAR)

    Institute of Scientific and Technical Information of China (English)

    Fan Luhong; Pi Yiming; Huang Shunji; Hou Yinming

    2006-01-01

    Inverse Synthetic Aperture Radar (ISAR) is an important means for target classification, recognition, identification and many other military applications. A simulation model of ISAR system is established after analyzing the principle of ISAR imaging, and then several ECM (Electronic Counter Measurement) techniques are studied. Simulation experiments are done on the basis of such research. The experimental result of the research can be used for ECM equipment.

  1. Improved Interferometric Synthetic Aperture Radar Processing via Advanced Co-registration and Phase Correction Techniques

    OpenAIRE

    M. Shahbazi; Mahdi Motagh

    2012-01-01

    Interferometric Synthetic Aperture Radar (InSAR) applies the interferograms of two or more SAR images to generate maps of surface deformation or digital elevation models. InSAR operational pro cessing chain for displacement map generation comprises of five major stages: co-registration and re-sampling, interferogram generation, flat-earth correction, topography correction and phase unwrapping. This paper discusses and evaluates the authors’ proposed algorithms for SAR image matchi ng and for ...

  2. Operational Use of Civil Space-Based Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Montgomery, Donald R. (Editor)

    1996-01-01

    Synthetic Aperture Radar (SAR) is a remote-sensing technology which uses the motion of the aircraft or spacecraft carrying the radar to synthesize an antenna aperture larger than the physical antenna to yield a high-spatial resolution imaging capability. SAR systems can thus obtain high-spatial resolution geophysical measurements of the Earth over wide surface areas, under all-weather, day/night conditions. This report was prepared to document the results of a six-month study by an Ad Hoc Interagency Working Group on the Operational Use of Civil (i.e., non-military) Space-based Synthetic Aperture Radar (SAR). The Assistant Administrator of NOAA for Satellite and Information Services convened this working group and chaired three meetings of the group over a six-month period. This action was taken in response to a request by the Associate Administrator of NASA for Mission to Planet Earth for an assessment of operational applications of SAR to be accomplished in parallel with a separate study requested of the Committee on Earth Studies of the Space Studies Board of the National Research Council on the scientific results of SAR research missions. The representatives of participating agencies are listed following the Preface. There was no formal charter for the working group or long term plans for future meetings. However, the working group may be reconstituted in the future as a coordination body for multiagency use of operational SAR systems.

  3. Coherent Performance Analysis of the HJ-1-C Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Li Hai-ying

    2014-06-01

    Full Text Available Synthetic Aperture Radar (SAR is a coherent imaging radar. Hence, coherence is critical in SAR imaging. In a coherent system, several sources can degrade performance. Based on the HJ-1-C SAR system implementation and sensor characteristics, this study evaluates the effect of frequency stability and pulse-to-pulse timing jitter on the SAR coherent performance. A stable crystal oscillator with short-term stability of 10×1.0−10 / 5 ms is used to generate the reference frequency by using a direct multiplier and divider. Azimuth ISLR degradation owing to the crystal oscillator phase noise is negligible. The standard deviation of the pulse-to-pulse timing jitter of HJ-1-C SAR is lower than 2ns (rms and the azimuth random phase error in the synthetic aperture time slightly degrades the side lobe of the azimuth impulse response. The mathematical expressions and simulation results are presented and suggest that the coherent performance of the HJ-1-C SAR system meets the requirements of synthetic aperture radar imaging.

  4. NASA L-SAR instrument for the NISAR (NASA-ISRO) Synthetic Aperture Radar mission

    Science.gov (United States)

    Hoffman, James P.; Shaffer, Scott; Perkovic-Martin, Dragana

    2016-05-01

    The National Aeronautics and Space Administration (NASA) in the United States and the Indian Space Research Organization (ISRO) have partnered to develop an Earth-orbiting science and applications mission that exploits synthetic aperture radar to map Earth's surface every 12 days or less. To meet demanding coverage, sampling, and accuracy requirements, the system was designed to achieve over 240 km swath at fine resolution, and using full polarimetry where needed. To address the broad range of disciplines and scientific study areas of the mission, a dual-frequency system was conceived, at L-band (24 cm wavelength) and S-band (10 cm wavelength). To achieve these observational characteristics, a reflector-feed system is considered, whereby the feed aperture elements are individually sampled to allow a scan-on-receive ("SweepSAR") capability at both L-band and S-band. The instrument leverages the expanding capabilities of on-board digital processing to enable real-time calibration and digital beamforming. This paper describes the mission characteristics, current status of the L-band Synthetic Aperture Radar (L-SAR) portion of the instrument, and the technology development efforts in the United States that are reducing risk on the key radar technologies needed to ensure proper SweepSAR operations.

  5. Apertures

    CERN Document Server

    Hansen, R C

    2014-01-01

    Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

  6. Retrieval of soil moisture using airborne synthetic- and real- aperture radar data at different spatial scales

    Science.gov (United States)

    Kim, S.; Tsang, L.; Liao, T.; Huang, H.; Jackson, T. J.

    2013-12-01

    For the studies of surface soil moisture, radar observations offer high spatial resolution through aperture synthesis. The spatial resolution may be tens of meters from airborne platform to a few kilometers for global mapping from spaceborne platforms such as the L-band Soil Moisture Active Passive (SMAP) mission. A suite of sophisticated radar scattering forward models 'data-cubes' were developed for 17 land cover classes that simulate the radar response to soil moisture, surface roughness, and diverse vegetation. The inversion of the forward models to estimate soil moisture becomes a well-constrained problem through time-series analysis and parameterization of vegetation structure through an empirical allometric relationship. The retrieval approach has been developed for application using SMAP radar observations. This paper studies the applicability of the approach to radar observations over various spatial scales. The high-resolution airborne L-band radar data were collected by the Uninhabited Aerial Vehicle Synthetic Aperture Radar during the SMAP Validation Experiment 2012 conducted near Winnipeg, Canada in 2012 over agriculture fields. During the six-week campaign period, there were three major drying cycles of surface soil moisture that occurred while the agricultural vegetation grew from bare condition to full canopy. The volumetric soil moisture and radar backscattering generally showed a positive relationship when the vegetation effect was not strong, such as over pasture fields, or when the vegetation effect did not change substantially over time, such as for wheat fields. However, the significant temporal changes in corn and soybean canopies from bare to full growth result in a reverse of this relationship over these fields. The data-cube retrieval approach was able to systematically correct for the effect of the changing vegetation. Errors in soil moisture retrieval ranged from 0.037 to 0.086 cm3/cm3, when evaluated over all the available fields. In

  7. Measurement of turbulence in the oceanic mixed layer using Synthetic Aperture Radar (SAR

    Directory of Open Access Journals (Sweden)

    S. G. George

    2012-09-01

    Full Text Available Turbulence in the surface layer of the ocean contributes to the transfer of heat, gas and momentum across the air-sea boundary. As such, study of turbulence in the ocean surface layer is becoming increasingly important for understanding its effects on climate change. Direct Numerical Simulation (DNS techniques were implemented to examine the interaction of small-scale wake turbulence in the upper ocean layer with incident electromagnetic radar waves. Hydrodynamic-electromagnetic wave interaction models were invoked to demonstrate the ability of Synthetic Aperture Radar (SAR to observe and characterise surface turbulent wake flows. A range of simulated radar images are presented for a turbulent surface current field behind a moving surface vessel, and compared with the surface flow fields to investigate the impact of turbulent currents on simulated radar backscatter. This has yielded insights into the feasibility of resolving small-scale turbulence with remote-sensing radar and highlights the potential for extracting details of the flow structure and characteristics of turbulence using SAR.

  8. Analysis of urban area land cover using SEASAT Synthetic Aperture Radar data

    Science.gov (United States)

    Henderson, F. M. (Principal Investigator)

    1980-01-01

    Digitally processed SEASAT synthetic aperture raar (SAR) imagery of the Denver, Colorado urban area was examined to explore the potential of SAR data for mapping urban land cover and the compatability of SAR derived land cover classes with the United States Geological Survey classification system. The imagery is examined at three different scales to determine the effect of image enlargement on accuracy and level of detail extractable. At each scale the value of employing a simplistic preprocessing smoothing algorithm to improve image interpretation is addressed. A visual interpretation approach and an automated machine/visual approach are employed to evaluate the feasibility of producing a semiautomated land cover classification from SAR data. Confusion matrices of omission and commission errors are employed to define classification accuracies for each interpretation approach and image scale.

  9. Interferometric synthetic aperture radar (InSAR)—its past, present and future

    Science.gov (United States)

    Lu, Zhong; Kwoun, Oh-Ig; Rykhus, R.P.

    2007-01-01

    Very simply, interferometric synthetic aperture radar (InSAR) involves the use of two or more synthetic aperture radar (SAR) images of the same area to extract landscape topography and its deformation patterns. A SAR system transmits electromagnetic waves at a wavelength that can range from a few millimeters to tens of centimeters and therefore can operate during day and night under all-weather conditions. Using SAR processing technique (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) radar signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image that represents the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets. InSAR imaging utilizes the interaction of electromagnetic waves, referred to as interference, to measure precise distances between the satellite antenna and ground resolution elements to derive landscape topography and its subtle change in elevation.

  10. Polarimetric analysis of radar backscatter from ground-based scatterometers and wheat biomass monitoring with advanced synthetic aperture radar images

    Science.gov (United States)

    He, Lei; Tong, Ling; Li, Yuxia; Chen, Yan; Tan, Longfei; Guo, Caizheng

    2016-04-01

    This article presents an analysis of the scattering measurements for an entire wheat growth cycle by ground-based scatterometers at a frequency of 5.3 GHz. Since wheat ears are related to wheat growth and yield, the radar backscatter of wheat was analyzed at two different periods, i.e., with and without wheat ears. Simultaneously, parameters such as wheat and soil characteristics as well as volume scattering and soil scattering were analyzed for the two periods during the entire growth cycle. Wheat ears have been demonstrated to have a great influence on radar backscatter; therefore, a modified version of water-cloud model used for retrieving biomass should consider the effect of wheat ears. This work presents two retrieval models based on the water-cloud model and adopts the advanced integral equation model to simulate the soil backscatter before the heading stage and the backscatter from the layer under wheat ears after the heading stage. The research results showed that the biomass retrieved from the advanced synthetic aperture radar (ASAR) images to agree well with the data measured in situ after setting the modified water-cloud model for the growth stages with ears. Furthermore, it was concluded that wheat ears should form an essential component of theoretical modeling as they influence the final yield.

  11. Climate Change Indicator for Hazard Identification of Indian North West Coast Marine Environment Using Synthetic Aperture Radar (sar)

    Science.gov (United States)

    Gambheer, Phani Raj

    2012-07-01

    Stormwater runoff, Petroleum Hydrocarbon plumes are found abundantly near coastal cities, coastal population settlements especially in developing nations as more than half the world's human population. Ever increasing coastal populations and development in coastal areas have led to increased loading of toxic substances, nutrients and pathogens. These hazards cause deleterious effects on the population in many ways directly or indirectly which lead to algal blooms, hypoxia, beach closures, and damage to coastal fisheries. Hence these pollution hazards are important and the coastal administrations and people need to be aware of such a danger lurking very close to them. These hazards due to their small size, dynamic and episodic in nature are difficult to be visualized or to sample using in-situ traditional scientific methods. Natural obstructions like cloud cover and complex coastal circulations can hinder to detect and monitor such occurrences in the selected areas chosen for observations. This study takes recourse to Synthetic Aperture Radar (SAR) imagery because the pollution hazards are easily detectable as surfactants are deposited on the sea surface, along with nutrients and pathogens, smoothing capillary and small gravity waves to produce areas of reduced backscatter compared with surrounding ocean. These black spots can be termed as `Ecologic Indicator' and formed probably due to stronger thermal stratification, a deepening event of thermocline. SAR imagery that delivers useful data better than others regardless of darkness or cloud cover, should be made as an important observational tool for assessment and monitoring marine pollution hazards in the areas close to coastal regions. Till now the effects of climate change, sea level rise and global warming seems to have not affected the coastal populace of India in intrusions of sea water but it takes significance to the human health as the tides dominate these latitudes with bringing these polluted waters. KEY

  12. Multichannel synthetic aperture radar signatures and imaging of a moving target

    International Nuclear Information System (INIS)

    An airborne multichannel synthetic aperture radar imaging process is analyzed to derive spatial image and spectral signatures of a point target moving at a constant velocity. These signatures are expressed in terms of the moving target focal position that changes with the antenna array element location and the relative target-to-radar velocity vector and, as a result, the geometric transformation between two coordinate frames. One frame is stationary while the other moves with the target. The resulting target image spectrum is used to formulate a moving target image refocusing algorithm and a calibration approach useful to compensate the image modulation due to the directional antenna pattern effects. The potential applications of the multichannel signatures to target motion estimation and adaptive image processing will be explored. (paper)

  13. Research on Motion Compensation for Airborne Forward Looking Synthetic Aperture Radar with Linear Array Antennas

    Directory of Open Access Journals (Sweden)

    Zhang Ying-jie

    2013-06-01

    Full Text Available Combined with Frequency-Modulated Continuous-Wave (FMCW technology, airborne forward-looking Synthetic Aperture Radar (SAR with linear array antennas can obtain the image in front of the aircraft and also have the advantages of FMCW radar such as small size and lightweight. Moreover, it is suitable to be installed on platform like helicopter and small unmanned aerial vehicle. Motion compensation for forward-looking SAR with linear array antennas is one of the key problems to obtain the image in front of the aircraft in practice. This paper analyses the influence of motion error in aircraft on echo model based on the geometry of forward looking SAR with linear array antennas, and proposes a motion compensation scheme. Moreover, the compensation scheme is applicable to an improved frequency scaling algorithm (FSA for FMCW forward looking SAR with linear array antennas. Finally, the compensation scheme is verified with the simulation.

  14. Rainfall observation from X-band, space-borne, synthetic aperture radar

    Directory of Open Access Journals (Sweden)

    J. A. Weinman

    2009-02-01

    Full Text Available Satellites carrying X-band Synthetic Aperture Radars (SAR have recently been launched by several countries. These provide new opportunities to measure precipitation with higher spatial resolution than has heretofore been possible. Two algorithms to retrieve precipitation from such measurements over land have been developed, and the retrieved rainfall distributions were found to be consistent. A maritime rainfall distribution obtained from dual frequency (X and C-band data was used to compute the Differential Polarized Phase Shift. The computed Differential Polarized Phase Shift compared well with the value measured from space. Finally, we show a comparison between a recent X-band SAR image of a precipitation distribution and an observation of the same rainfall from ground-based operational weather radar. Although no quantitative comparison of retrieved and conventional rainfall distributions could be made with the available data at this time, the results presented here point the way to such comparisons.

  15. Effectiveness of WRF wind direction for retrieving coastal sea surface wind from synthetic aperture radar

    DEFF Research Database (Denmark)

    Takeyama, Yuko; Ohsawa, Teruo; Kozai, Katsutoshi;

    2013-01-01

    Wind direction is required as input to the geophysical model function (GMF) for the retrieval of sea surface wind speed from a synthetic aperture radar (SAR) images. The present study verifies the effectiveness of using the wind direction obtained from the weather research and forecasting model...... directions: the meso‐analysis of the Japan Meteorological Agency (MANAL), the SeaWinds microwave scatterometer on QuikSCAT and the National Center for Environmental Prediction final operational global analysis data (NCEP FNL). In comparison with the errors of the SAR‐retrieved wind speeds obtained using the...

  16. Segmentation of synthetic aperture radar image using multiscale information measure-based spectral clustering

    Institute of Scientific and Technical Information of China (English)

    Haixia Xu; Zheng Tian; Mingtao Ding

    2008-01-01

    @@ A multiscale information measure (MIM), calculable from per-pixel wavelet coefficients, but relying on global statistics of synthetic aperture radar (SAR) image, is proposed. It fully exploits the variations in speckle pattern when the image resolution varies from course to fine, thus it can capture the intrinsic texture of the scene backscatter and the texture due to speckle simultaneously. Graph spectral segmentation methods based on MIM and the usual similarity measure are carried out on two real SAR images.Experimental results show that MIM can characterize texture information of SAR image more effectively than the commonly used similarity measure.

  17. Ocean wave diffraction in near-shore regions observed by Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Observation and analysis of ocean wave diffraction in near-shore and near-island region was performed with Synthetic Aperture Radar (SAR) data, using an optimized retrieval method named parameterized first-guess spectrum retrieval method. The results retrieved from ERS-SAR and ENVISAT-ASAR images showed that, in the region sheltered by land jut, the energy of long waves is reduced by 10%-20% and that the propagation direction of long waves is changed due to the effect of topography. In the shadow zone behind the island, ocean wave can propagate along the seashore instead of perpendicular to the coastline, as shown by SAR images.

  18. Fusion of multistatic synthetic aperture radar data to obtain a superresolution image

    International Nuclear Information System (INIS)

    When using a single emitter and a single receiver, the Synthetic Aperture Radar (SAR) data gives information in the Fourier domain of the scene over a line segment whose width is related to the bandwidth of the emitted signal. The mathematical problem of image reconstruction in SAR then becomes a Fourier Synthesis (FS) inverse problem. When there are more than one emitter or receiver looking at the same scene, the problem becomes fusion and inversion. In this paper we report a Bayesian joint data fusion and inversion method to obtain a super resolution image. The proposed method shows a good performance on real data obtained at ONERA in France.

  19. Offshore wind resource mapping for Europe by Synthetic Aperture Radar (SAR) satellite data

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete

    2015-01-01

    satellite remote sensing observations and atmospheric modelling. The satellite data include Synthetic Aperture Radar (SAR) from the European Space Agency from Envisat and the Copernicus mission Sentinel-1. SAR has the advantage of high spatial resolution such that we can cover near-coastal areas where many...... wind farms are planned. In the Danish RUNE project near-shore offshore winds are investigate from SAR, atmospheric modelling and ground-based remote sensing lidar. In the European Space Agency project ResGrow SAR wind resource maps at various locations in the European Seas are used to estimate the wind...

  20. Application of improved equivalent edge currents in synthetic aperture radar imaging

    Institute of Scientific and Technical Information of China (English)

    Yanwei Zhao; Ping Zhou; Xiangyang Zhang; Min Zhang

    2010-01-01

    Target modeling and scattering function calculating are important prerequisites and groundwork for the synthetic aperture radar (SAR) imaging simulation. According to the difficult prob-lems that normal methods cannot calculate the scattering function of electrically large object under the condition to wideband, an ef-fective method of improved equivalent edge currents is presented and applied to SAR imaging simulation for the first time. This method improves calculating velocity and has relatively high pre-cision. The concrete steps of applying the method are given. By way of the simulation experiment, the effectiveness of the method is verified.

  1. Detection and suppression of narrow band RFI for synthetic aperture radar imaging

    OpenAIRE

    Yang Lin; Zheng Huifang; Feng Jin; Li Ning; Chen Jiaqi

    2015-01-01

    Radio frequency interference (RFI) is becoming more and more frequently, which makes it an important issue in SAR imaging. RFI presented in synthetic aperture radar either on purpose or inadvertent will distort the useful SAR echoes, thus degrade the SAR image quality. To resolve this issue, a long time study was carried out to study the characteristic of the RFI through the RFI-affected spaceborne and airborne SAR data. Based on the narrow band nature of RFI, this paper proposes a new proces...

  2. Imaging Algorithm for Rotor Synthetic Aperture Radar Using Stepped-frequency Waveform

    Directory of Open Access Journals (Sweden)

    Zeng Cao

    2014-08-01

    Full Text Available For ROtor Synthetic Aperture Radar (ROSAR using the stepped-frequency waveform, an imaging method based on Range Migration Correction (RMC for ROSAR is proposed. First, the signal model of ROSAR using stepped-frequency waveform is derived; Second, the range migration correction in frequency domain is proposed; Third, the high-resolution images are achieved by using the ω-k algorithm; Finally, the azimuth resolution performance is analyzed. Simulation results demonstrate the effectiveness and high resolution performance of the proposed method.

  3. Survey of Study on Internal Waves Detection in Synthetic Aperture Radar Image

    Directory of Open Access Journals (Sweden)

    Chong Jin-song

    2013-12-01

    Full Text Available In recent years, Internal Waves (IWs detection in Synthetic Aperture Radar (SAR image has received considerable attentions in the area of marine remote sensing and has already become one of the most important marine applications of SAR. Typical research results at home and abroad are reviewed. Three areas of researches are introduced and summarized, including parameter inversion method of IWs, the effect of different SAR parameter and wind field conditions on IWs imaging, the 2-dimentional SAR imaging simulation of IWs.

  4. Towards a Semantic Interpretation of Urban Areas with Airborne Synthetic Aperture Radar Tomography

    Science.gov (United States)

    D'Hondt, O.; Guillaso, S.; Hellwich, O.

    2016-06-01

    In this paper, we introduce a method to detect and reconstruct building parts from tomographic Synthetic Aperture Radar (SAR) airborne data. Our approach extends recent works in two ways: first, the radiometric information is used to guide the extraction of geometric primitives. Second, building facades and roofs are extracted thanks to geometric classification rules. We demonstrate our method on a 3 image L-Band airborne dataset over the city of Dresden, Germany. Experiments show how our technique allows to use the complementarity between the radiometric image and the tomographic point cloud to extract buildings parts in challenging situations.

  5. Detection of landmines and UXO using advanced synthetic aperture radar technology

    Science.gov (United States)

    Schreiber, Eric; Peichl, Markus; Dill, Stephan; Heinzel, Andreas; Bischeltsrieder, Florian

    2016-05-01

    A main problem of effective landmine and UXO decontamination is efficient and reliable detection and localization of suspicious objects in reasonable time. This requirement demands for fast sensors investigating large areas with sufficient spatial resolution and sensitivity. Ground penetrating radar (GPR) is a suitable tool and is considered as a complementing sensor since nearly two decades. However, most GPRs operate in very close distance to ground in a rather punctual method of operation. In contrast, synthetic aperture radar (SAR) is a technique allowing fast and laminar stand-off investigation of an area. TIRAMI-SAR is imaging radar at lower microwaves for fast close-in detection of buried and unburied objects on a larger area. This allows efficient confirmation of a threat by investigating such regions of detection by other sensors. For proper object detection sufficient spatial resolution is required. Hence the SAR principle is applied. SAR for landmine/UXO detection can be applied by side-looking radar moved on safe ground along the area of interest, being typically the un-safe ground. Additionally, reliable detection of buried and unburied objects requires sufficient suppression of background clutter. For that purpose TIRAMI-SAR is using several antennas in multi-static configuration and wave polarization together with advanced SAR processing. The advantages and necessity of a multi-static antenna configuration for this kind of GPR approach is illustrated in the paper.

  6. Waveform analysis of airborne synthetic aperture radar altimeter over Arctic sea ice

    Directory of Open Access Journals (Sweden)

    M. Zygmuntowska

    2013-03-01

    Full Text Available Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat was launched in 2010 carrying a Ku-band Radar Altimeter (SIRAL designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types has been analyzed. A set of parameters has been defined to characterize the difference in strength and width of the returned power waveforms. With a Bayesian based method it is possible to classify about 80% of the waveforms by three parameters: maximum of the returned power echo, the trailing edge width and pulse peakiness. Furthermore, the radar power echo maximum can be used to minimize the rate of false detection of leads compared to the widely used Pulse Peakiness parameter. The possibility to distinguish between different ice types and open water allows to improve the freeboard retrieval and the conversion into sea ice thickness where surface type dependent values for the sea ice density and snow load can be used.

  7. Worldwide Weather Radar Imagery May Allow Substantial Increase in Meteorite Fall Recovery

    Science.gov (United States)

    Fries, Marc; Matson, Robert; Schaefer, Jacob; Fries, Jeffery; Hankey, Mike; Anderson, Lindsay

    2014-01-01

    Weather radar imagery is a valuable new technique for the rapid recovery of meteorite falls, to include falls which would not otherwise be recovered (e.g. Battle Mountain). Weather radar imagery reveals about one new meteorite fall per year (18 falls since 1998), using weather radars in the United States alone. However, an additional 75 other nations operate weather radar networks according to the UN World Meteorological Organization (WMO). If the imagery of those radars were analyzed, the current rate of meteorite falls could be improved considerably, to as much as 3.6 times the current recovery rate based on comparison of total radar areal coverage. Recently, the addition of weather radar imagery, seismometry and internet-based aggregation of eyewitness reports has improved the speed and accuracy of fresh meteorite fall recovery [e.g. 1,2]. This was demonstrated recently with the radar-enabled recovery of the Sutter's Mill fall [3]. Arguably, the meteorites recovered via these methods are of special scientific value as they are relatively unweathered, fresh falls. To illustrate this, a recent SAO/NASA ADS search using the keyword "meteorite" shows that all 50 of the top search results included at least one named meteorite recovered from a meteorite fall. This is true even though only 1260 named meteorite falls are recorded among the >49,000 individual falls recorded in the Meteoritical Society online database. The US NEXRAD system used thus far to locate meteorite falls covers most of the United States' surface area. Using a WMO map of the world's weather radars, we estimate that the total coverage of the other 75 national weather radar networks equals about 3.6x NEXRAD's coverage area. There are two findings to draw from this calculation: 1) For the past 16 years during which 18 falls are seen in US radar data, there should be an additional 65 meteorite falls recorded in worldwide radar imagery. Also: 2) if all of the world's radar data could be analyzed, the

  8. Change Detection in Synthetic Aperture Radar Images Based on Deep Neural Networks.

    Science.gov (United States)

    Gong, Maoguo; Zhao, Jiaojiao; Liu, Jia; Miao, Qiguang; Jiao, Licheng

    2016-01-01

    This paper presents a novel change detection approach for synthetic aperture radar images based on deep learning. The approach accomplishes the detection of the changed and unchanged areas by designing a deep neural network. The main guideline is to produce a change detection map directly from two images with the trained deep neural network. The method can omit the process of generating a difference image (DI) that shows difference degrees between multitemporal synthetic aperture radar images. Thus, it can avoid the effect of the DI on the change detection results. The learning algorithm for deep architectures includes unsupervised feature learning and supervised fine-tuning to complete classification. The unsupervised feature learning aims at learning the representation of the relationships between the two images. In addition, the supervised fine-tuning aims at learning the concepts of the changed and unchanged pixels. Experiments on real data sets and theoretical analysis indicate the advantages, feasibility, and potential of the proposed method. Moreover, based on the results achieved by various traditional algorithms, respectively, deep learning can further improve the detection performance. PMID:26068879

  9. Onboard Data Compression of Synthetic Aperture Radar Data: Status and Prospects

    Science.gov (United States)

    Klimesh, Matthew A.; Moision, Bruce

    2008-01-01

    Synthetic aperture radar (SAR) instruments on spacecraft are capable of producing huge quantities of data. Onboard lossy data compression is commonly used to reduce the burden on the communication link. In this paper an overview is given of various SAR data compression techniques, along with an assessment of how much improvement is possible (and practical) and how to approach the problem of obtaining it. Synthetic aperture radar (SAR) instruments on spacecraft are capable of acquiring huge quantities of data. As a result, the available downlink rate and onboard storage capacity can be limiting factors in mission design for spacecraft with SAR instruments. This is true both for Earth-orbiting missions and missions to more distant targets such as Venus, Titan, and Europa. (Of course for missions beyond Earth orbit downlink rates are much lower and thus potentially much more limiting.) Typically spacecraft with SAR instruments use some form of data compression in order to reduce the storage size and/or downlink rate necessary to accommodate the SAR data. Our aim here is to give an overview of SAR data compression strategies that have been considered, and to assess the prospects for additional improvements.

  10. Oil detection in a coastal marsh with polarimetric Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Ramsey, Elijah W., III; Rangoonwala, Amina; Suzuoki, Yukihiro; Jones, Cathleen E.

    2011-01-01

    The National Aeronautics and Space Administration's airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR) sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  11. Oil Detection in a Coastal Marsh with Polarimetric Synthetic Aperture Radar (SAR

    Directory of Open Access Journals (Sweden)

    Cathleen E. Jones

    2011-12-01

    Full Text Available The National Aeronautics and Space Administration’s airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD and Cloude-Pottier (CP decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  12. Exact spectrum of non-linear chirp scaling and its application in geosynchronous synthetic aperture radar imaging

    Directory of Open Access Journals (Sweden)

    Chen Qi

    2013-07-01

    Full Text Available Non-linear chirp scaling (NLCS is a feasible method to deal with time-variant frequency modulation (FM rate problem in synthetic aperture radar (SAR imaging. However, approximations in derivation of NLCS spectrum lead to performance decline in some cases. Presented is the exact spectrum of the NLCS function. Simulation with a geosynchronous synthetic aperture radar (GEO-SAR configuration is implemented. The results show that using the presented spectrum can significantly improve imaging performance, and the NLCS algorithm is suitable for GEO-SAR imaging after modification.

  13. Interseismic Deformation of the Altyn Tagh Fault Determined by Interferometric Synthetic Aperture Radar (InSAR) Measurements

    OpenAIRE

    Sen Zhu; Caijun Xu; Yangmao Wen; Yang Liu

    2016-01-01

    The Altyn Tagh Fault (ATF) is one of the major left-lateral strike-slip faults in the northeastern area of the Tibetan Plateau. In this study, the interseismic deformation across the ATF at 85°E was measured using 216 interferograms from 33 ENVISAT advanced synthetic aperture radar images on a descending track acquired from 2003 to 2010, and 66 interferograms from 15 advanced synthetic aperture radar images on an ascending track acquired from 2005 to 2010. To retrieve the pattern of interseis...

  14. A Simple Low-Cost Shared-Aperture Dual-Band Dual-Polarized High Gain Antenna for Synthetic Aperture Radars

    OpenAIRE

    Qin, Fan; Gao, Steven; Qi, Luo; Mao, Chunxu; Gu, Chao; Wei, Gao; Xu, Jiadong; Li, Jianzhou; Wu, Changying; Zheng, Kuisong; Zheng, Shufeng

    2016-01-01

    This paper presents a novel shared-aperture dual-band dual-polarized high-gain antenna for potential applications in synthetic aperture radars (SAR). To reduce the complexity of SAR antennas, a dual-band dual-polarized high gain antenna based on the concept of Fabry-Perot resonant cavity is designed. This antenna operates in both C and X bands with a frequency ratio of 1:1.8. To form two separate resonant cavities, two frequency selective surface (FSS) layers are employed, leading to high fle...

  15. STORM: A New Airborne Polarimetric Real-Aperture Radar for Earth Observations

    Science.gov (United States)

    Podvin, D. Hauser. T.; Dechambre, M.; Valentin, R.; Caudal, G.; Daloze, J.-F.

    2003-04-01

    The successful launch of the Envisat in March 2002 offers new possibilities for estimating geophysical quantities characterizing continental or sea surface using the multi-polarization ASAR. In addition, in the context of the preparation of future missions which will embark polarimetric SAR (e.g. RADARSAT2) it is important to better assess the benefit of multi-polarization or polarimetric SAR systems. Airborne radar systems remain a very useful way to validate satellite measurements and to develop or validate algorithms needed to retrieve geophysical quantities from the radar measurements. CETP has designed and developed a new airborne radar called STORM] , which has a full polarimetric capability. STORM is derived from two previous versions of airborne radars developed at CETP, namely RESSAC (Hauser et al, JGR 1992) and RENE (Leloch-Duplex et al, Annales of Telecommunications, 1996). STORM is a real-aperture, C-Band system with a FM/CW transmission and with a rotating antenna to explore in azimuth. It offers a polarization diversity, receiving the complex signal in amplitude and phase simultaneously in H and V polarizations, which makes it possible to analyze the radar cross-section in HH, VV, HV, and other cross-polarized terms related to the scattering matrix. The antenna are pointed towards the surface with a mean incidence angle of 20° and a 3-dB aperture of about 30° in elevation and 8° in azimuth. The backscattered signal is analyzed from nadir to about 35° along the look-direction in 1012 range gates every 1.53m. The first tests with this system have been carried out in October 2001 over corner reflectors , over grass and ocean. In this workshop, we will present a validation of this system based on the results obtained with this first data set. In particular, we will present the calibration method of the complex signal (amplitude, phase), and distribution of phase differences (HH/VV, HV/VH) obtained over the different scatters (corner reflectors, grass

  16. Maximum a posteriori classification of multifrequency, multilook, synthetic aperture radar intensity data

    International Nuclear Information System (INIS)

    The authors present a maximum a posteriori (MAP) classifier for classifying multifrequency, multilook, single polarization, synthetic aperture radar (SAR) intensity data into regions or ensembles of pixels of homogeneous and similar radar backscatter characteristics. A model for the prior joint distribution of the multifrequency SAR intensity data is combined with a Markov random field for representing the interactions between region labels to obtain an expression for the posterior distribution of the region labels given the multifrequency SAR observations. The maximization of the posterior distribution yields Bayes's optimum region labeling or classification of the SAR data or its MAP estimate. The performance of the MAP classifier is evaluated by using computer-simulated multilook SAR intensity data as a function of the parameters in the classification process. Multilook SAR intensity data are shown to yield higher classification accuracies than one-look SAR complex amplitude data. Examples using actual two-frequency, four-look, SAR intensity data acquired by the NASA/jet Propulsion Laboratory airborne polarimetric SAR are presented. The MAP classifier is extended to the case in which the radar backscatter from the remotely sensed surface varies within the SAR image because of incidence angle effects. The results obtained illustrate the practicality of the method for combining SAR intensity observations acquired at two different frequencies and for improving classification accuracy of SAR data. 26 refs., 4 figs., 6 tabs

  17. Imaging Algorithm for Arc Synthetic Aperture Radar Using Frequency Modulated Continuous Wave

    Directory of Open Access Journals (Sweden)

    Lu Matt

    2016-08-01

    Full Text Available Arc Synthetic Aperture Radar (Arc-SAR is a new operation-mode radar that is suitable for wide observation in certain areas. With its high resolution, wide observation area, and short repetition visit period, Arc-SAR is widely used in monitoring deformation measurements, landslides, and natural hazards. Because of the special movement of Arc-SAR, the BackproPagation Algorithm (BPA is widely used in its image processing. Here, we propose a novel two-dimensional frequency domain algorithm to process an Arc-SAR signal. First, we derive a signal model of Arc-SAR based on that of frequency-modulated continuous-wave radar. Next, because the length of the arm is far shorter than the distance of the antenna to the target, the signal can be processed in a 2D frequency domain. Finally, we analyze the error of the frequency method used. This algorithm has the advantages of high computation speed and accuracy. The simulation and experimental data results confirm the effectiveness and validity of the proposed method.

  18. Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

    Directory of Open Access Journals (Sweden)

    M. Zygmuntowska

    2013-08-01

    Full Text Available Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types have been analyzed. A set of parameters has been defined to characterize the differences in strength and width of the returned power waveforms. With a Bayesian-based method, it is possible to classify about 80% of the waveforms from three parameters: maximum of the returned power waveform, the trailing edge width and pulse peakiness. Furthermore, the maximum of the power waveform can be used to reduce the number of false detections of leads, compared to the widely used pulse peakiness parameter. For the pulse peakiness the false classification rate is 12.6% while for the power maximum it is reduced to 6.5%. The ability to distinguish between different ice types and leads allows us to improve the freeboard retrieval and the conversion from freeboard into sea ice thickness, where surface type dependent values for the sea ice density and snow load can be used.

  19. Contribution of multitemporal polarimetric synthetic aperture radar data for monitoring winter wheat and rapeseed crops

    Science.gov (United States)

    Betbeder, Julie; Fieuzal, Remy; Philippets, Yannick; Ferro-Famil, Laurent; Baup, Frederic

    2016-04-01

    This paper aims to evaluate the contribution of multitemporal polarimetric synthetic aperture radar (SAR) data for winter wheat and rapeseed crops parameters [height, leaf area index, and dry biomass (DB)] estimation, during their whole vegetation cycles in comparison to backscattering coefficients and optical data. Angular sensitivities and dynamics of polarimetric indicators were also analyzed following the growth stages of these two common crop types using, in total, 14 radar images (Radarsat-2), 16 optical images (Formosat-2, Spot-4/5), and numerous ground data. The results of this study show the importance of correcting the angular effect on SAR signals especially for copolarized signals and polarimetric indicators associated to single-bounce scattering mechanisms. The analysis of the temporal dynamic of polarimetric indicators has shown their high potential to detect crop growth changes. Moreover, this study shows the high interest of using SAR parameters (backscattering coefficients and polarimetric indicators) for crop parameters estimation during the whole vegetation cycle instead of optical vegetation index. They particularly revealed their high potential for rapeseed height and DB monitoring [i.e., Shannon entropy polarimetry (r2=0.70) and radar vegetation index (r2=0.80), respectively].

  20. Multitemporal L- and C-Band Synthetic Aperture Radar To Highlight Differences in Water Status Among Boreal Forest and Wetland Systems in the Yukon Flats, Interior Alaska

    Science.gov (United States)

    Balser, Andrew W.; Wylie, Bruce K.

    2010-01-01

    Tracking landscape-scale water status in high-latitude boreal systems is indispensible to understanding the fate of stored and sequestered carbon in a climate change scenario. Spaceborne synthetic aperture radar (SAR) imagery provides critical information for water and moisture status in Alaskan boreal environments at the landscape scale. When combined with results from optical sensor analyses, a complementary picture of vegetation, biomass, and water status emerges. Whereas L-band SAR showed better inherent capacity to map water status, C-band had much more temporal coverage in this study. Analysis through the use of L- and C-band SARs combined with Landsat Enhanced Thematic Mapper Plus (ETM+) enables landscape stratification by vegetation and by seasonal and interannual hydrology. Resultant classifications are highly relevant to biogeochemistry at the landscape scale. These results enhance our understanding of ecosystem processes relevant to carbon balance and may be scaled up to inform regional carbon flux estimates and better parameterize general circulation models (GCMs).

  1. Automated analysis of radar imagery of Venus: handling lack of ground truth

    OpenAIRE

    Burl, M. C.; Fayyad, Usama M.; Perona, Pietro; Smyth, Padhraic

    1994-01-01

    Lack of verifiable ground truth is a common problem in remote sensing image analysis. For example, consider the synthetic aperture radar (SAR) image data of Venus obtained by the Magellan spacecraft. Planetary scientists are interested in automatically cataloging the locations of all the small volcanoes in this data set; however, the problem is very difficult and cannot be performed with perfect reliability even by human experts. Thus, training and evaluating the performance of an automatic a...

  2. Motion of the Lambert Glacier estimated by using differential Interferometric Synthetic Aperture Radar

    International Nuclear Information System (INIS)

    Interferometric Synthetic Aperture Radar (InSAR) is one of the most promising remote sensing technologies and has been widely applied in constructing topographic information and estimating the deformation of the Earth's surface. Ice velocity is an important parameter for calculating the mass balance and modelling ice shelve dynamics. Ice velocity is also an important indicator for climate changes. Therefore, it plays an important role in studying the global climate change and global sea level rise. In this paper, the ERS-1/2 tandem data and the ASTER GDEM are combined together to obtained the deformation in line of sight by using the differential Interferometric SAR for the Lambert Amery glacier in Antarctica. Then the surface parallel assumption is adopted in order to achieve the ice flow velocity. The results showed that ice velocity would be increased along the Lambert glacier; the maximum ice velocity would be reach about 450m/year in the study area

  3. Coherent interferometric imaging for synthetic aperture radar in the presence of noise

    International Nuclear Information System (INIS)

    This paper shows that the coherent interferometric imaging strategy originally proposed in the context of passive or active arrays of antennas can be implemented for synthetic aperture radar, in which a single antenna is used as an emitter and as a receiver at successive positions along a trajectory. The idea is to backpropagate the cross correlations of the recorded signals over selected frequency-spatial windows rather than the signals themselves. The theoretical analysis shows that the signal-to-noise ratio can be enhanced dramatically compared to the standard matched filter processing, without any loss of resolution. This holds true when the fluctuations of the recorded signals have a spatial correlation (along the antenna trajectory) that is larger than the distance between two successive positions of the antenna and smaller than the length of the antenna trajectory. As a result, a good compromise between resolution and deblurring can be achieved by an appropriate choice of the spatial window size

  4. Detection of oil spills near offshore installations using synthetic aperture radar (SAR)

    International Nuclear Information System (INIS)

    Remote sensing using synthetic aperture radar (SAR) is attracting increasing interest for the detection of oil spills from offshore oil installations. Three systems are already operating and three more are planned. SAR can provide high spatial resolution and is not affected by the time of day or cloud conditions. Examples of images obtained from UK and Norwegian offshore installations are shown and their interpretation are explained. SAR image analysis is used by a satellite-based oil spill monitoring service covering the Norwegian sector of the North Sea and part of the North Sea, the Norwegian Sea and the Baltic Sea. An algorithm has been developed at the Nansen Environmental and Remote Sensing Centre (NERSC) in Norway to help distinguish between oil spills, natural films, current shear zones and rain cells

  5. A multiscale approach to a synthetic aperture radar in dispersive random media

    International Nuclear Information System (INIS)

    We consider synthetic aperture radar (SAR) image formation in the situation when the propagation medium is random and dispersive. The propagation model is the Klein–Gordon equation with a random index of refraction and a random dispersive term. We show via a multiscale analysis how medium heterogeneities and dispersion affect the image. In fact, in a situation with a strong source chirp signal, the main effect of the medium heterogeneities is to introduce random phase distortions in the SAR data. We carry out a novel scaling analysis that gives a precise characterization of this canonical phase perturbation and how it affects image resolution and stability. The main effect of the phase perturbation is to reduce the azimuthal resolution and the signal-to-noise ratio and we quantify this performance degradation. (paper)

  6. Comparison of synthetic aperture radar and impact-echo imaging for detecting delamination in concrete

    International Nuclear Information System (INIS)

    In this paper we evaluate the utility of microwave and mechanical wave nondestructive testing techniques to detect delamination in reinforced concrete bridge deck mock-up samples. The mechanical wave tests comprise air-coupled impact-echo measurements, while the microwave measurements comprise three-dimensional synthetic aperture radar imaging using wideband reflectometery in the frequency range of 1–4 GHz. The results of these investigations are presented in terms of images that are generated from these data. Based on a comparison of the results, we show that the two methods are complementary, in that provide distinct capabilities for defect detection. More specifically, the former approach is unable to detect depth of a delaminated region, while the latter may provide this information. Therefore, the two methods may be used in a complementary fashion (i.e., data fusion) to give more comprehensive information about the 3D location of delamination

  7. Object Hierarchy-based Supervised Characterisation ofSynthetic Aperture Radar Sensor Images

    Directory of Open Access Journals (Sweden)

    Ish Rishabh

    2008-01-01

    Full Text Available A method of supervised characterisation of synthetic aperture radar (SAR satellite imageshas been discussed in which simple object shape features of satellite images have been usedto classify and describe the terrain types. This scheme is based on a multilevel approach inwhich objects of interest are first segmented out from the image and subsequently characterisedbased on their shape features. Once all objects have been characterised, the entire image canbe characterised. Emphasis has been laid on the hierarchical information extraction from theimage which enables greater flexibility in characterising the image and is not restricted to mereclassification. The paper also describes a method for giving relative importance among features,i.e., to give more weights to those features that are better than others in distinguishing betweencompeting classes. A method of comparing two SAR sensor images based on terrain elementspresent in the images has also been described here.

  8. Implementation of a fast time-domain processor for FMCW Synthetic Aperture Radar data

    Science.gov (United States)

    Frioud, Max; Wellig, Peter; Stanko, Stephan; Meier, Erich

    2015-10-01

    For the purpose of getting sensitive information relevant to civil or military security, high-resolution airborne Synthetic Aperture Radar (SAR) provides the possibility to organize missions at short notice regardless of the daylight and of the weather conditions. The use of compact millimeter-wave FMCW SAR systems allows reaching these goals more safely and at lower cost using unmanned lightweight platforms. As a counterpart these platforms are relatively unstable, making the data-processing more difficult. In order to reach optimum focusing quality also in unfavorable flight conditions or for highly non-linear tracks we developed a fast Time-Domain Processor that relies on parallelization using the GPU resources. A production areal processing rate as high as 6 km2/h using 20 cm ground pixel spacing on a single PC station was achieved. The processing quality and efficiency is demonstrated using real data from the MIRANDA35 Ka-band SAR system.

  9. National Aeronautics and Space Administration and the Indian Space Research Organisation Synthetic Aperture Radar Mission Concept

    Science.gov (United States)

    Bawden, G. W.; Rosen, P. A.; Dubayah, R.; Hager, B. H.; Joughin, I. R.

    2014-12-01

    The U.S. National Aeronautics and Space Administration and the Indian Space Research Organisation are planning a synthetic aperture radar (currently named NISAR) mission for launch in 2020. The mission is a dual L- and S-band polarimetric SAR satellite with a 12-day interferometric orbit and 240 km wide ground swath. The 3-year mission will have a circular sun synchronous orbit (6 am and 6 pm) with a 98° inclination and 747 km altitude that will provide systematic global coverage. Its primary science objectives are to: measure solid Earth surface deformation (earthquakes, volcanic unrest, land subsidence/uplift, landslides); track and understand cryosphere dynamics (glaciers, ice sheets, sea ice, and permafrost); characterize and track changes in vegetation structure and wetlands for understanding ecosystem dynamics and carbon cycle; and support global disaster response. We will describe the current mission concept: the satellite design/capabilities, spacecraft, launch vehicle, and data flow.

  10. Preparations to use Synthetic Aperture Radar (SAR) in sea ice remote sensing in the Baltic Sea

    Science.gov (United States)

    Leppäranta, M.; Kuittinen, R.; Kemppainen, H.

    Remote sensing methods are largely used in ice mapping in the Baltic Sea. The next significant step will come true in next decade with satellite Synthetic Aperture Radars (SAR); in particular, SAR is weather independent and provides information of ice roughness. As an early phase of a joint Finnish-Swedish research programme BEPERS (Bothnian Experiment in Preparation for ERS-1), a field experiment ``BEPERS Pilot Study'' was carried through in 1987. The French VARAN-S X-band SAR was chartered for this experiment. Four study areas of around 10 × 50 km size were chosen representing different ice types and conditions. Intensive ground and remote sensing observations were made for correct interpretation of the SAR images. Digital analyses of the SAR images showed that the ice cover could be classified into four classes: 1) open water or bare smooth ice, 2) smooth of slightly deformed ice, 3) ridges and 4) leads with brash ice.

  11. CROSS-RANGE RESOLUTION OF SYNTHETIC APERTURE RADAR BASED ON DIVING MODEL

    Institute of Scientific and Technical Information of China (English)

    Sun Bing; Zhou Yinqing; Chen Jie

    2011-01-01

    This paper concentrates on the cross-range resolution of Synthetic Aperture Radar (SAR) based on diving model.In comparison to the azimuth resolution,the cross-range resolution can manifest the two-dimensional resolution ability of the imaging sensor SAR correctly.The diving model of SAR is an extended model from the conventional stripmap model,and the cross-range resolution expression is deduced from the equivalent linear frequency modulation pulses' compression.This expression points out that only the cross-range velocity component of the horizontal velocity contributes to the cross-range resolution.Also the cross-range resolution expressions and the performance of the conventional stripmap operation,squint side-look operation and beam circular-scanning operation are discussed.The cross-range resolution expression based on diving model will provide more general and more accurate reference.

  12. Feature Understanding and Target Detection for Sparse Microwave Synthetic Aperture Radar Images

    Directory of Open Access Journals (Sweden)

    Zhang Zenghui

    2016-02-01

    Full Text Available Sparse microwave imaging using sparse priors of observed scenes in space, time, frequency, or polarization domain and echo data with sampling rate smaller than the traditional Nyquist rate as well as optimization algorithms for reconstructing the microwave images of observed scenes has many advantages over traditional microwave imaging systems. In sparse microwave imaging, image acquisition and representation vary; therefore, new feature analysis and cognitive interpretation theories and methods should be developed based on current research results. In this study, we analyze the statistical properties of sparse Synthetic Aperture Radar (SAR images and changes in point, line and regional features induced by sparse reconstruction. For SAR images recovered by the spatial sparse model, the statistical distribution degrades, whereas points and lines can be accurately extracted by low sampling rates. Furthermore, the target detection method based on sparse SAR images is studied. Owing to a weak background noise, target detection is easier using sparse SAR images than traditional ones.

  13. Parameters estimation of sinusoidal frequency modulation signal with application in synthetic aperture radar imaging

    Science.gov (United States)

    Wang, Yong; Wang, Zhaofa; Zhao, Bin; Xu, Liang

    2016-04-01

    A method for estimating the parameters of the sinusoidal frequency modulation (SFM) signal is presented in this paper. Based on the modified discrete sinusoid frequency modulation transform (DSFMT), the SFM signal can be transformed into the DSFMT domain where it is energy-concentrated and then the parameters can be estimated by the global maximum. To search for the location of the global maximum with less computational load, particle swarm optimization is used in this paper. Then the algorithm is used in the synthetic aperture radar imaging with high frequency vibration of the platform, and the focus performance can be improved significantly. Simulation results demonstrate the effectiveness of the method proposed in this paper.

  14. Analysis of wideband forward looking synthetic aperture radar for sensing land mines

    Science.gov (United States)

    Kovvali, Narayan; Carin, Lawrence

    2004-08-01

    Signal processing algorithms are considered for the analysis of wideband, forward looking synthetic aperture radar data and for sensing metal and plastic land mines, with principal application to unpaved roads. Simple prescreening algorithms are considered for reduction of the search space required for a subsequent classifier. The classifier employs features based on viewing the target at multiple ranges, with classification implemented via a support vector machine and a relevance vector machine (RVM). Concerning classifier training, we consider cases for which training is performed on both mine and nonmine (clutter) data. In addition, motivated by the fact that the clutter statistics may vary significantly between the training and testing data, we also consider RVM implementation when we only train on mine data.

  15. Focusing Azimuth-Invariant Bistatic Synthetic Aperture Radar Data Based on a Polynomial Model

    Institute of Scientific and Technical Information of China (English)

    ZHONG Hua; LIU Xing-zhao; WANG Jun-feng

    2009-01-01

    In this paper, a focusing approach is presented to widen the use of efficient monostatic imaging algorithms for azimuth-invariant bistatic synthetic aperture radar (SAR) data. The bistatic range history is modeled by a polynomial of azimuth time. Using this model, an analytic form of the signal spectrum in the 2D frequency domain is derived, and a simple single-valued relation between the transmitter and receive ranges is established. In this way, a lot of monostatic image formation algorithms can be extended for the bistatic SAR data, and a bistatic chirp scaling algorithm is developed as an application of the new approach. This algorithm can be used to process the azimuth-invariant bistatic configuration where the transmitter and receiver platforms are moving on parallel tracks with the same velocity. In addition, some simulation results are given to demonstrate the validity of the proposed approach.

  16. Physics-Based Predictions for Coherent Change Detection Using X-Band Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Mark Preiss

    2005-12-01

    Full Text Available A theoretical model is developed to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The model is derived using a dyadic form for surface reflectivity in the Kirchhoff approximation. This permits the combination of Kirchhoff theory and spotlight synthetic aperture radar (SAR image formation theory. The resulting model is used to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The theoretical model is applied to SAR images formed before and after surface changes observed by a repeat-pass SAR system. The change in surface associated with a tyre track following vehicle passage is modelled and SAR coherency estimates are obtained. Predicted coherency distributions for both the change and no-change scenarios are used to estimate receiver operator curves for the detection of the changes using a high-resolution, X-band SAR system.

  17. Radar imagery interpretation to assess the hydrocarbon potential of four sites in the Philippines

    Energy Technology Data Exchange (ETDEWEB)

    1988-11-17

    The Republic of the Philippines is intensely interested in the identification, development, and conservation of natural resources. In keeping with this, the Government of the Philippines has recently completed a nationwide sedimentary basin evaluation program to assess hydrocarbon potential and assist in future exploration activities. This program of collection and interpretation of the radar imagery was designed to augment and complement the existing data base. The primary objective of the project was to further the goals of international energy development by aiding the Republic of the Philippines in the assessment of potential petroleum and geothermal prospects within the areas imaged. Secondary goals were to assist the Republic of the Philippines in utilizing state-of-the-art radar remote sensing technology for resource exploration, and to train key Philippines scientists in the use of imaging radar data. 29 refs., 30 figs., 14 tabs.

  18. Bistatic Synthetic Aperture Radar Imaging of Moving Targets using Ultra-Narrowband Continuous Waveforms

    CERN Document Server

    Wang, Ling

    2013-01-01

    We consider a synthetic aperture radar (SAR) system that uses ultra-narrowband continuous waveforms (CW) as an illumination source. Such a system has many practical advantages, such as the use of relatively simple, low-cost and low-power transmitters, and in some cases, using the transmitters of opportunity, such as TV, radio stations. Additionally, ultra-narrowband CW signals are suitable for motion estimation due to their ability to acquire high resolution Doppler information. In this paper, we present a novel synthetic aperture imaging method for moving targets using a bi-static SAR system transmitting ultra-narrowband continuous waveforms. Our method exploits the high Doppler resolution provided by ultra-narrowband CW signals to image both the scene reflectivity and to determine the velocity of multiple moving targets. Starting from the first principle, we develop a novel forward model based on the temporal Doppler induced by the movement of antennas and moving targets. We form the reflectivity image of t...

  19. On the convergence of the phase gradient autofocus algorithm for synthetic aperture radar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, M.J.

    1996-01-01

    Synthetic Aperture Radar (SAR) imaging is a class of coherent range and Doppler signal processing techniques applied to remote sensing. The aperture is synthesized by recording and processing coherent signals at known positions along the flight path. Demands for greater image resolution put an extreme burden on requirements for inertial measurement units that are used to maintain accurate pulse-to-pulse position information. The recently developed Phase Gradient Autofocus algorithm relieves this burden by taking a data-driven digital signal processing approach to estimating the range-invariant phase aberrations due to either uncompensated motions of the SAR platform or to atmospheric turbulence. Although the performance of this four-step algorithm has been demonstrated, its convergence has not been modeled mathematically. A new sensitivity study of algorithm performance is a necessary step towards this model. Insights that are significant to the application of this algorithm to both SAR and to other coherent imaging applications are developed. New details on algorithm implementation identify an easily avoided biased phase estimate. A new algorithm for defining support of the point spread function is proposed, which promises to reduce the number of iterations required even for rural scenes with low signal-to-clutter ratios.

  20. Moving Target Indication via RADARSAT-2 Multichannel Synthetic Aperture Radar Processing

    Directory of Open Access Journals (Sweden)

    Dragošević MV

    2010-01-01

    Full Text Available With the recent launches of the German TerraSAR-X and the Canadian RADARSAT-2, both equipped with phased array antennas and multiple receiver channels, synthetic aperture radar, ground moving target indication (SAR-GMTI data are now routinely being acquired from space. Defence R&D Canada has been conducting SAR-GMTI trials to assess the performance and limitations of the RADARSAT-2 GMTI system. Several SAR-GMTI modes developed for RADARSAT-2 are described and preliminary test results of these modes are presented. Detailed equations of motion of a moving target for multiaperture spaceborne SAR geometry are derived and a moving target parameter estimation algorithm developed for RADARSAT-2 (called the Fractrum Estimator is presented. Limitations of the simple dual-aperture SAR-GMTI mode are analysed as a function of the signal-to-noise ratio and target speed. Recently acquired RADARSAT-2 GMTI data are used to demonstrate the capability of different system modes and to validate the signal model and the algorithm.

  1. Remotely Sensed Active Layer Thickness (ReSALT at Barrow, Alaska Using Interferometric Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Kevin Schaefer

    2015-03-01

    Full Text Available Active layer thickness (ALT is a critical parameter for monitoring the status of permafrost that is typically measured at specific locations using probing, in situ temperature sensors, or other ground-based observations. Here we evaluated the Remotely Sensed Active Layer Thickness (ReSALT product that uses the Interferometric Synthetic Aperture Radar technique to measure seasonal surface subsidence and infer ALT around Barrow, Alaska. We compared ReSALT with ground-based ALT obtained using probing and calibrated, 500 MHz Ground Penetrating Radar at multiple sites around Barrow. ReSALT accurately reproduced observed ALT within uncertainty of the GPR and probing data in ~76% of the study area. However, ReSALT was less than observed ALT in ~22% of the study area with well-drained soils and in ~1% of the area where soils contained gravel. ReSALT was greater than observed ALT in some drained thermokarst lake basins representing ~1% of the area. These results indicate remote sensing techniques based on InSAR could be an effective way to measure and monitor ALT over large areas on the Arctic coastal plain.

  2. Change Detection in Synthetic Aperture Radar Images Using a Multiscale-Driven Approach

    Directory of Open Access Journals (Sweden)

    Olaniyi A. Ajadi

    2016-06-01

    Full Text Available Despite the significant progress that was achieved throughout the recent years, to this day, automatic change detection and classification from synthetic aperture radar (SAR images remains a difficult task. This is, in large part, due to (a the high level of speckle noise that is inherent to SAR data; (b the complex scattering response of SAR even for rather homogeneous targets; (c the low temporal sampling that is often achieved with SAR systems, since sequential images do not always have the same radar geometry (incident angle, orbit path, etc.; and (d the typically limited performance of SAR in delineating the exact boundary of changed regions. With this paper we present a promising change detection method that utilizes SAR images and provides solutions for these previously mentioned difficulties. We will show that the presented approach enables automatic and high-performance change detection across a wide range of spatial scales (resolution levels. The developed method follows a three-step approach of (i initial pre-processing; (ii data enhancement/filtering; and (iii wavelet-based, multi-scale change detection. The stand-alone property of our approach is the high flexibility in applying the change detection approach to a wide range of change detection problems. The performance of the developed approach is demonstrated using synthetic data as well as a real-data application to wildfire progression near Fairbanks, Alaska.

  3. A High Resolution, Light-Weight, Synthetic Aperture Radar for UAV Application

    International Nuclear Information System (INIS)

    (U) Sandia National Laboratories in collaboration with General Atomics (GA) has designed and built a high resolution, light-weight, Ku-band Synthetic Aperture Radar (SAR) known as ''Lynx''. Although Lynx can be operated on a wide variety of manned and unmanned platforms, its design is optimized for use on medium altitude Unmanned Aerial Vehicles (UAVS). In particular, it can be operated on the Predator, I-GNAT, and Prowler II platforms manufactured by GA. (U) The radar production weight is less than 120 lb and operates within a 3 GHz band from 15.2 GHz to 18.2 GHz with a peak output power of 320 W. Operating range is resolution and mode dependent but can exceed 45 km in adverse weather (4 mm/hr rain). Lynx has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in strip map mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside and ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers

  4. A Large Aperture UWB Antenna Array for Real Beam Radar Imaging

    Directory of Open Access Journals (Sweden)

    Chao-Hsiang Liao

    2012-01-01

    Full Text Available The development of four-element ultra-wideband (UWB comb taper slot antenna array with 18 cm element spacing for real beam radar imaging is described. The four-element UWB array system with optimum element spacing is analyzed by energy pattern. A wideband double ridge horn antenna is used as the transmitting antenna, the developed large aperture UWB array is used as the receiving antenna. The transmitting antenna and the receiving antenna are combined with impulse time domain measurement system to achieve real beam radar imaging. The receiving impulse signals at various positions are processed by the time delay and sum algorithm. The examples of several aluminum cans have been verified in the resolution and compared with using the UWB array as a receive antenna and the double ridge horn as a transmit antenna in the test setup. The crossrange resolution of UWB antenna array is better than wideband double ridge horn antenna because the beam width of UWB array is narrower.

  5. Operational Mapping of Soil Moisture Using Synthetic Aperture Radar Data: Application to the Touch Basin (France

    Directory of Open Access Journals (Sweden)

    Jean François Desprats

    2007-10-01

    Full Text Available Soil moisture is a key parameter in different environmental applications, suchas hydrology and natural risk assessment. In this paper, surface soil moisture mappingwas carried out over a basin in France using satellite synthetic aperture radar (SARimages acquired in 2006 and 2007 by C-band (5.3 GHz sensors. The comparisonbetween soil moisture estimated from SAR data and in situ measurements shows goodagreement, with a mapping accuracy better than 3%. This result shows that themonitoring of soil moisture from SAR images is possible in operational phase. Moreover,moistures simulated by the operational Météo-France ISBA soil-vegetation-atmospheretransfer model in the SIM-Safran-ISBA-Modcou chain were compared to radar moistureestimates to validate its pertinence. The difference between ISBA simulations and radarestimates fluctuates between 0.4 and 10% (RMSE. The comparison between ISBA andgravimetric measurements of the 12 March 2007 shows a RMSE of about 6%. Generally,these results are very encouraging. Results show also that the soil moisture estimatedfrom SAR images is not correlated with the textural units defined in the European Soil Geographical Database (SGDBE at 1:1000000 scale. However, dependence was observed between texture maps and ISBA moisture. This dependence is induced by the use of the texture map as an input parameter in the ISBA model. Even if this parameter is very important for soil moisture estimations, radar results shown that the textural map scale at 1:1000000 is not appropriate to differentiate moistures zones.

  6. An Autonomous Cryobot Synthetic Aperture Radar for Subsurface Exploration of Europa

    Science.gov (United States)

    Pradhan, O.; Gasiewski, A. J.

    2015-12-01

    We present the design and field testing of a forward-looking end-fire synthetic aperture radar (SAR) for the 'Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. Results proving the feasibility of an end-fire SAR system for vehicle guidance and obstacle avoidance in a sub-surface ice environment will be presented. Data collected by the SAR will also be used for constructing sub-surface images of the glacier which can be used for: (i) mapping of englacial features such as crevasses, moulins, and embedded liquid water and (ii) ice-depth and glacier bed analysis to construct digital elevation models (DEM) that can help in the selection of crybot trajectories and future drill sites for extracting long-term climate records. The project consists of three parts, (i) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form agile radiating elements, (ii) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (iii) field testing of the SAR in melt holes. The antennas have been designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar system was also designed and integrated at CET utilizing rugged RF components and FPGA based digital processing. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. The antennas are designed to operate inside ice while being immersed in a thin layer of surrounding low-conductivity melt water. Small holes in the corners of the cavities allow flooding of these cavities with the same melt-water thus allowing for quarter-wavelength cavity-backed reflection. Testing of

  7. Estimating snow water equivalent (SWE) using interferometric synthetic aperture radar (InSAR)

    Science.gov (United States)

    Deeb, Elias J.

    Since the early 1990s, radar interferometry and interferometric synthetic aperture radar (InSAR) have been used extensively to measure changes in the Earth's surface. Previous research has presented theory for estimating snow properties, including potential for snow water equivalent (SWE) retrieval, using InSAR. The motivation behind using remote sensing to estimate SWE is to provide a more complete, continuous set of "observations" to assist in water management operations, climate change studies, and flood hazard forecasting. The research presented here primarily investigates the feasibility of using the InSAR technique at two different wavelengths (C-Band and L-Band) for SWE retrieval of dry snow within the Kuparuk watershed, North Slope, Alaska. Estimating snow distribution around meteorological towers on the coastal plain using a three-day repeat orbit of C-Band InSAR data was successful (Chapter 2). A longer wavelength L-band SAR is evaluated for SWE retrievals (Chapter 3) showing the ability to resolve larger snow accumulation events over a longer period of time. Comparisons of InSAR estimates and late spring manual sampling of SWE show a R2 = 0.61 when a coherence threshold is used to eliminate noisy SAR data. Qualitative comparisons with a high resolution digital elevation model (DEM) highlight areas of scour on windward slopes and areas of deposition on leeward slopes. When compared to a mid-winter transect of manually sampled snow depths, the InSAR SWE estimates yield a RMSE of 2.21cm when a bulk snow density is used and corrections for bracketing the satellite acquisition timing is performed. In an effort to validate the interaction of radar waves with a snowpack, the importance of the "dry snow" assumption for the estimation of SWE using InSAR is tested with an experiment in Little Cottonwood Canyon, Alta, Utah (Chapter 5). Snow wetness is shown to have a significant effect on the velocity of propagation within the snowpack. Despite the radar

  8. Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

    Science.gov (United States)

    Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  9. Rapid damage mapping for the 2015 M7.8 Gorkha earthquake using synthetic aperture radar data from COSMO-SkyMed and ALOS-2 satellites

    Science.gov (United States)

    Yun, Sang-Ho; Hudnut, Kenneth W.; Owen, Susan; Webb, Frank; Simons, Mark; Sacco, Patrizia; Gurrola, Eric; Manipon, Gerald; Liang, Cunren; Fielding, Eric; Milillo, Pietro; Hua, Hook; Coletta, Alessandro

    2015-01-01

    The 25 April 2015 Mw 7.8 Gorkha earthquake caused more than 8000 fatalities and widespread building damage in central Nepal. The Italian Space Agency’s COSMO–SkyMed Synthetic Aperture Radar (SAR) satellite acquired data over Kathmandu area four days after the earthquake and the Japan Aerospace Exploration Agency’s Advanced Land Observing Satellite-2 SAR satellite for larger area nine days after the mainshock. We used these radar observations and rapidly produced damage proxy maps (DPMs) derived from temporal changes in Interferometric SAR coherence. Our DPMs were qualitatively validated through comparison with independent damage analyses by the National Geospatial-Intelligence Agency and the United Nations Institute for Training and Research’s United Nations Operational Satellite Applications Programme, and based on our own visual inspection of DigitalGlobe’s WorldView optical pre- versus postevent imagery. Our maps were quickly released to responding agencies and the public, and used for damage assessment, determining inspection/imaging priorities, and reconnaissance fieldwork.

  10. Rapid, Repeat-sample Monitoring of Crustal Deformations and Environmental Phenomena with the Uninhabited Aerial Vehicle Synthetic Aperture Radar

    Science.gov (United States)

    Smith, Robert C.

    2006-01-01

    The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR) mission being developed by the Jet Propulsion Laboratory and the Dryden Flight Research Center in support of NASA s Science Mission Directorate. UAVSAR's unique ability to fly a repeatable flight path, along with an electronically steerable array, allows interferometric data to be obtained with accuracies measured in millimeters. Deploying the radar on an airborne platform will also allow for radar images to be collected and compared with images from the same area taken hours or even years later - providing for long-term trending and near real-time notification of changes and deformations. UAVSAR s data processing algorithms will provide for near-real time data reduction providing disaster planning and response teams with highly accurate data to aid in the prediction of, and response to, natural phenomena. UAVSAR data can be applied to increasing our understanding of the processes behind solid earth, cryosphere, carbon cycle and other areas of interest in earth science. Technologies developed for UAVSAR may also be applicable to a future earth-orbiting InSAR mission and possibly for missions to the Moon or Mars. The UAVSAR is expected to fly on a Gulfstream III aircraft this winter, followed by a flight test program lasting until the second half of 2007. Following radar calibration and data reduction activities, the platform will be ready for science users in the summer of 2008.

  11. Indoor experimental facility for airborne synthetic aperture radar (SAR) configurations - rail-SAR

    Science.gov (United States)

    Kirose, Getachew; Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Koenig, Francois; Narayanan, Ram M.

    2014-05-01

    The Army Research Laboratory (ARL) is developing an indoor experimental facility to evaluate and assess airborne synthetic-aperture-radar-(SAR)-based detection capabilities. The rail-SAR is located in a multi-use facility that also provides a base for research and development in the area of autonomous robotic navigation. Radar explosive hazard detection is one key sensordevelopment area to be investigated at this indoor facility. In particular, the mostly wooden, multi-story building houses a two (2) story housing structure and an open area built over a large sandbox. The housing structure includes reconfigurable indoor walls which enable the realization of multiple See-Through-The-Wall (STTW) scenarios. The open sandbox, on the other hand, allows for surface and buried explosive hazard scenarios. The indoor facility is not rated for true explosive hazard materials so all targets will need to be inert and contain surrogate explosive fills. In this paper we discuss the current system status and describe data collection exercises conducted using canonical targets and frequencies that may be of interest to designers of ultra-wideband (UWB) airborne, ground penetrating SAR systems. A bi-static antenna configuration will be used to investigate the effects of varying airborne SAR parameters such as depression angle, bandwidth, and integration angle, for various target types and deployment scenarios. Canonical targets data were used to evaluate overall facility capabilities and limitations. These data is analyzed and summarized for future evaluations. Finally, processing techniques for dealing with RF multi-path and RFI due to operating inside the indoor facility are described in detail. Discussion of this facility and its capabilities and limitations will provide the explosive hazard community with a great airborne platform asset for sensor to target assessment.

  12. Progress report on the NASA/JPL airborne synthetic aperture radar system

    Science.gov (United States)

    Lou, Y.; Imel, D.; Chu, A.; Miller, T.; Moller, D.; Skotnicki, W.

    2001-01-01

    AIRSAR has served as a test-bed for both imaging radar techniques and radar technologies for over a decade. In fact, the polarimetric, cross-track interferometric, and along-track introferometric radar techniques were all developed using AIRSAR.

  13. Digital Beamforming Synthetic Aperture Radar (DBSAR): Performance Analysis During the Eco-3D 2011 and Summer 2012 Flight Campaigns

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Carter, Lynn; Ranson, K. Jon; Vega, Manuel; Osmanoglu, Batuhan; Lee, SeungKuk; Sun, Guoqing

    2014-01-01

    The Digital Beamforming Synthetic Aperture radar (DBSAR) is a state-of-the-art airborne radar developed at NASA/Goddard for the implementation, and testing of digital beamforming techniques applicable to Earth and planetary sciences. The DBSAR measurements have been employed to study: The estimation of vegetation biomass and structure - critical parameters in the study of the carbon cycle; The measurement of geological features - to explore its applicability to planetary science by measuring planetary analogue targets. The instrument flew two test campaigns over the East coast of the United States in 2011, and 2012. During the campaigns the instrument operated in full polarimetric mode collecting data from vegetation and topography features.

  14. Road-Aided Ground Slowly Moving Target 2D Motion Estimation for Single-Channel Synthetic Aperture Radar

    OpenAIRE

    Zhirui Wang; Jia Xu; Zuzhen Huang; Xudong Zhang; Xiang-Gen Xia; Teng Long; Qian Bao

    2016-01-01

    To detect and estimate ground slowly moving targets in airborne single-channel synthetic aperture radar (SAR), a road-aided ground moving target indication (GMTI) algorithm is proposed in this paper. First, the road area is extracted from a focused SAR image based on radar vision. Second, after stationary clutter suppression in the range-Doppler domain, a moving target is detected and located in the image domain via the watershed method. The target’s position on the road as well as its radial...

  15. Monitoring the effect of restoration measures in Indonesian peatlands by radar satellite imagery.

    Science.gov (United States)

    Jaenicke, J; Englhart, S; Siegert, F

    2011-03-01

    In the context of the ongoing climate change discussions the importance of peatlands as carbon stores is increasingly recognised in the public. Drainage, deforestation and peat fires are the main reasons for the release of huge amounts of carbon from peatlands. Successful restoration of degraded tropical peatlands is of high interest due to their huge carbon store and sequestration potential. The blocking of drainage canals by dam building has become one of the most important measures to restore the hydrology and the ecological function of the peat domes. This study investigates the capability of using multitemporal radar remote sensing imagery for monitoring the hydrological effects of these measures. The study area is the former Mega Rice Project area in Central Kalimantan, Indonesia, where peat drainage and forest degradation is especially intense. Restoration measures started in July 2004 by building 30 large dams until June 2008. We applied change detection analysis with more than 80 ENVISAT ASAR and ALOS PALSAR images, acquired between 2004 and 2009. Radar signal increases of up to 1.36 dB show that high frequency multitemporal radar satellite imagery can be used to detect an increase in peat soil moisture after dam construction, especially in deforested areas with a high density of dams. Furthermore, a strong correlation between cross-polarised radar backscatter coefficients and groundwater levels above -50 cm was found. Monitoring peatland rewetting and quantifying groundwater level variations is important information for vegetation re-establishment, fire hazard warning and making carbon emission mitigation tradable under the voluntary carbon market or REDD (Reducing Emissions from Deforestation and Degradation) mechanism. PMID:20971549

  16. Observations and modeling of the current deformation in Afar using Synthetic Aperture Radar Interferometry

    Science.gov (United States)

    Tomic, Jelena

    The Afar system is a unique place on Earth where a triple rift junction may be emerging. As the three rifts separating Arabia, Nubia and Somalia plates have not achieved a complete connection at present, I observe a 200 km wide area of complex surface deformation. A variety of extensional structures including a network of faults, fissures, dikes, and volcanic centers are collectively accommodating far field movement of the surrounding plates. Understanding the nature and distribution of the deformation over this vast region is critical since here I observe the transition between established oceanic ridges (the Red Sea and the Aden-Goubbet ridges) and continental deformation. In this study I use the technique of Synthetic Aperture Radar Interferometry (InSAR) to analyze radar data of the Afar region, and to construct a 10 yr timeline of surface displacement over a 200 km by 400 km area. By combining data acquired from ascending and descending passes I construct a two-dimensional velocity maps of the region. The maps show localized extensional deformation across the Asal-Ghoubbet rift segment accommodating the diverging motion of the Arabia-Somalia plates, as well as regional uplift asymmetrically distributed north and south of the Asal Rift area. The vertical velocity map in the rift indicates subsidence of the rift floor with respect to the rift shoulders, accommodated by fault creep. To interpret the observed velocity across the Asal rift I develop a 2-dimensional and a 3-dimensional dislocation model using a combination of dikes, sill and faults embedded in an elastic half space. The forward modeling allows me to place the overall geometry of sub-surface structures and estimate rates of dike and sill inflation, and fault movement. Then I construct a 3-dimensional model to perform a least-squares inversion of the radar-derived velocity maps. The results show an inflating body centered under the Fieale volcano expanding at a rate of 2 106 m3/yr. Faults bordering

  17. Detection of flooded urban areas in high resolution Synthetic Aperture Radar images using double scattering

    Science.gov (United States)

    Mason, D. C.; Giustarini, L.; Garcia-Pintado, J.; Cloke, H. L.

    2014-05-01

    Flooding is a particular hazard in urban areas worldwide due to the increased risks to life and property in these regions. Synthetic Aperture Radar (SAR) sensors are often used to image flooding because of their all-weather day-night capability, and now possess sufficient resolution to image urban flooding. The flood extents extracted from the images may be used for flood relief management and improved urban flood inundation modelling. A difficulty with using SAR for urban flood detection is that, due to its side-looking nature, substantial areas of urban ground surface may not be visible to the SAR due to radar layover and shadow caused by buildings and taller vegetation. This paper investigates whether urban flooding can be detected in layover regions (where flooding may not normally be apparent) using double scattering between the (possibly flooded) ground surface and the walls of adjacent buildings. The method estimates double scattering strengths using a SAR image in conjunction with a high resolution LiDAR (Light Detection and Ranging) height map of the urban area. A SAR simulator is applied to the LiDAR data to generate maps of layover and shadow, and estimate the positions of double scattering curves in the SAR image. Observations of double scattering strengths were compared to the predictions from an electromagnetic scattering model, for both the case of a single image containing flooding, and a change detection case in which the flooded image was compared to an un-flooded image of the same area acquired with the same radar parameters. The method proved successful in detecting double scattering due to flooding in the single-image case, for which flooded double scattering curves were detected with 100% classification accuracy (albeit using a small sample set) and un-flooded curves with 91% classification accuracy. The same measures of success were achieved using change detection between flooded and un-flooded images. Depending on the particular flooding

  18. Anti-jamming of Inverse Synthetic Aperture Radar based on Slope-varying Linear Frequency Modulation Signal

    Directory of Open Access Journals (Sweden)

    Zhu Yupeng

    2009-09-01

    Full Text Available Deceptive jamming technology against inverse synthetic aperture radar is matured now, which is meaningful in military application. But the research on anti-jamming technology for inverse synthetic aperture radar (ISAR is still not a mature technology. Through the analysis on the theory of deceptive jamming technology against ISAR, a new method for anti-jamming against ISAR based on linear frequency modulation signal’s frequency slope-varying is presented. The false target echo energy is suppressed due to frequency modulation slope mis-matching. Doppler domain averaging is adopted for improving the quality of the ISAR image, which helps automatic target recognition. Simulation result based on simulating data shows the validity of the new algorithm.Defence Science Journal, 2009, 59(5, pp.537-544, DOI:http://dx.doi.org/10.14429/dsj.59.1556

  19. Direction synthesis in DOA estimation for monostatic multiple input multiple output (MIMO) radar based on synthetic impulse and aperture radar (SIAR) and its performance analysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new direction synthetic method for monostatic multiple input multiple output (MIMO) radar is presented based on synthetic impulse and aperture radar (SIAR) system. Concerned with the monostatic MIMO radar which simultaneously emits orthogonal signals with multi-carrier-frequency and possesses sparsely distributed transmitting and receiving arrays with respective location, as well as the situation for the presence of multipath propagation in the low flying target’s echo, the method integrates the aperture of the transmitting arrays with the receiving arrays to form the digital beam-forming (DBF) in azimuth and elevation dimensions. And a study has been made of planar general MUSIC algorithm based on decorrelating the multipath signals of multi-carrier-frequency MIMO radar. Through compensat-ing the phase delay of both the transmitting and the receiving arrays and synthe-sizing the transmitting beam in two dimensions at the receiver, the angular resolu-tion and measurement accuracy are improved and the computational complexity is reduced after transforming the three-dimensional (3D) parameter estimation prob-lem into a two-dimensional (2D) one. Finally, the Cramer-Rao Bounds (CRBs) of DOA estimation for azimuth and elevation is put forward with the exsiting multipath propagation. Results of computer simulation demonstrate the validity of the new method.

  20. Direction synthesis in DOA estimation for monostatic multiple input multiple output(MIMO) radar based on synthetic impulse and aperture radar (SIAR) and its performance analysis

    Institute of Scientific and Technical Information of China (English)

    ZHAO GuangHui; CHEN BaiXiao; ZHU ShouPing

    2008-01-01

    A new direction synthetic method for monostatic multiple input multiple output (MIMO) radar is presented based on synthetic impulse and aperture radar (SIAR) system. Concerned with the monostatic MIMO radar which simultaneously emits orthogonal signals with multi-carrier-frequency and possesses sparsely distributed transmitting and receiving arrays with respective location, as well as the situation for the presence of multipath propagation in the low flying target's echo, the method integrates the aperture of the transmitting arrays with the receiving arrays to form the digital beam-forming (DBF) in azimuth and elevation dimensions. And a study has been made of planar general MUSIC algorithm based on decorrelating the multipath signals of multi-carrier-frequency MIMO radar. Through compensat-ing the phase delay of both the transmitting and the receiving arrays and synthe-sizing the transmitting beam in two dimensions at the receiver, the angular resolu-tion and measurement accuracy are improved and the computational complexity is reduced after transforming the three-dimensional (3D) parameter estimation prob-lem into a two-dimensional (2D) one. Finally, the Cramer-Rao Bounds (CRBs) of DOA estimation for azimuth and elevation is put forward with the exsitJng multipath propagation. Results of computer simulation demonstrate the validity of the new method.

  1. Synthetic Aperture Radar (sar) Based Classifiers for Land Applications in Germany

    Science.gov (United States)

    Suresh, G.; Gehrke, R.; Wiatr, T.; Hovenbitzer, M.

    2016-06-01

    Land cover information is essential for urban planning and for land cover change monitoring. This paper presents an overview of the work conducted at the Federal Agency for Cartography and Geodesy (BKG) with respect to Synthetic Aperture Radar (SAR) based land cover classification. Two land cover classification approaches using SAR images are reported in this paper. The first method involves a rule-based classification using only SAR backscatter intensity while the other method involves supervised classification of a polarimetric composite of the same SAR image. The LBM-DE has been used for training and validation of the SAR classification results. Images acquired from the Sentinel-1a satellite are used for classification and the results have been reported and discussed. The availability of Sentinel-1a images that are weather and daylight independent allows for the creation of a land cover classification system that can be updated and validated periodically, and hence, be used to assist other land cover classification systems that use optical data. With the availability of Sentinel-2 data, land cover classification combining Sentinel-1a and Sentinel-2 images present a path for the future.

  2. Research on synthetic aperture radar imaging technology of one-dimensional layered rough surfaces

    Institute of Scientific and Technical Information of China (English)

    Ji Wei-Jie; Tong Chuang-Ming

    2013-01-01

    A quick and exact imaging method for one-dimensional layered rough surfaces is proposed in this paper to study the scattering characteristics of a layered medium that exists widely in nature.The boundary integral equations of layered rough surfaces are solved by using the propagation-inside-layer expansion combined with the forward and backward spectral acceleration method (PILE+FB-SA),and the back scattering data are obtained.Then,a conventional synthetic aperture radar (SAR) imaging procedure called back projection method is used to generate a two-dimensional (2D) image of the layered rough surfaces.Combined with the relative dielectric permittivity of realistic soil,the random rough surfaces with Gauss spectrum are used to simulate the layered medium with rough interfaces.Since the back scattering data are computed by using the fast numerical method,this method can be used to study layered rough surfaces with any parameter,which has a great application value in the detection and remote sensing areas.

  3. Reduction of ionospheric distortions for spaceborne synthetic aperture radar with the help of image registration

    International Nuclear Information System (INIS)

    We propose a robust technique for reducing the ionospheric distortions in spaceborne synthetic aperture radar (SAR) images. It is based on probing the terrain on two distinct carrier frequencies. Compared to our previous work on the subject (Smith and Tsynkov 2011 SIAM J. Imaging Sciences 4 501–42), the increase in robustness is achieved by applying an area-based image registration algorithm to the two images obtained on two frequencies. This enables an accurate evaluation of the shift between the two images, which, in turn, translates into an accurate estimate of the total electron content and its along-track gradient in the ionosphere. These estimates allow one to correct the matched filter and thus improve the quality of the image. Moreover, for the analysis of SAR resolution in the current paper we take into account the Ohm conductivity in the ionosphere (in addition to its temporal dispersion), and also consider the true Kolmogorov spectrum of the ionospheric turbulence, as opposed to its approximate representation that we have used previously. (paper)

  4. Generation of large-scale digital elevation models via synthetic aperture radar interferometry

    International Nuclear Information System (INIS)

    It is investigated the possibility to generate a large-scale Digital Elevation Model by applying the Synthetic Aperture Radar interferometry technique and using tandem data acquired by the ERS-1/ERS-2 sensors. The presented study is mainly focused on the phase unwrapping step that represents the most critical point of the overall processing chain. In particular, it is concentrated on the unwrapping problems related to the use of a large ERS tandem data set that, in order to be unwrapped, must be partitioned. The paper discusses the inclusion of external information (even rough) of the scene topography, the application of a region growing unwrapping technique and the insertion of possible constraints on the phase to be retrieved in order to minimize the global unwrapping errors. The main goal is the generation of a digital elevation model relative to an area of 300 km by 100 km located in the southern part of Italy. Comparisons between the achieved result and a precise digital terrain model, relative to a smaller area, are also included

  5. Research on synthetic aperture radar imaging technology of one-dimensional layered rough surfaces

    International Nuclear Information System (INIS)

    A quick and exact imaging method for one-dimensional layered rough surfaces is proposed in this paper to study the scattering characteristics of a layered medium that exists widely in nature. The boundary integral equations of layered rough surfaces are solved by using the propagation-inside-layer expansion combined with the forward and backward spectral acceleration method (PILE+FB-SA), and the back scattering data are obtained. Then, a conventional synthetic aperture radar (SAR) imaging procedure called back projection method is used to generate a two-dimensional (2D) image of the layered rough surfaces. Combined with the relative dielectric permittivity of realistic soil, the random rough surfaces with Gauss spectrum are used to simulate the layered medium with rough interfaces. Since the back scattering data are computed by using the fast numerical method, this method can be used to study layered rough surfaces with any parameter, which has a great application value in the detection and remote sensing areas. (general)

  6. Synthetic aperture radar imaging based on attributed scatter model using sparse recovery techniques

    Institute of Scientific and Technical Information of China (English)

    苏伍各; 王宏强; 阳召成

    2014-01-01

    The sparse recovery algorithms formulate synthetic aperture radar (SAR) imaging problem in terms of sparse representation (SR) of a small number of strong scatters’ positions among a much large number of potential scatters’ positions, and provide an effective approach to improve the SAR image resolution. Based on the attributed scatter center model, several experiments were performed with different practical considerations to evaluate the performance of five representative SR techniques, namely, sparse Bayesian learning (SBL), fast Bayesian matching pursuit (FBMP), smoothed l0 norm method (SL0), sparse reconstruction by separable approximation (SpaRSA), fast iterative shrinkage-thresholding algorithm (FISTA), and the parameter settings in five SR algorithms were discussed. In different situations, the performances of these algorithms were also discussed. Through the comparison of MSE and failure rate in each algorithm simulation, FBMP and SpaRSA are found suitable for dealing with problems in the SAR imaging based on attributed scattering center model. Although the SBL is time-consuming, it always get better performance when related to failure rate and high SNR.

  7. In-situ data collection for oil palm tree height determination using synthetic aperture radar

    Science.gov (United States)

    Pohl, C.; Loong, C. K.

    2016-04-01

    The oil palm is recognized as the “golden crop,” producing the highest oil yield among oil seed crops. Malaysia, the world's second largest producer of palm oil, has 16 per cent of its territory planted with oil palms. To cope with the increasing global demand on edible oil, additional areas of oil palm are forecast to increase globally by 12 to 19 million hectares by 2050. Due to the limited land bank in Malaysia, new strategies have to be developed to avoid unauthorized clearing of primary forest for the use of oil palm cultivation. Microwave remote sensing could play a part by providing relevant, timely and accurate information for a plantation monitoring system. The use of synthetic aperture radar (SAR) has the advantage of daylight- and weather-independence, a criterion that is very relevant in constantly cloud-covered tropical regions, such as Malaysia. Using interferometric SAR, (InSAR) topographical and tree height profiles of oil palm plantations can be created; such information is useful for mapping oil palm age profiles of the plantations in the country. This paper reports on the use of SAR and InSAR in a multisensory context to provide up-to-date information at plantation level. Remote sensing and in-situ data collection for tree height determination are described. Further research to be carried out over the next two years is outlined.

  8. Land subsidence detection using synthetic aperture radar (SAR) in Sidoarjo Mudflow area

    Science.gov (United States)

    Yulyta, Sendy Ayu; Taufik, Muhammad; Hayati, Noorlaila

    2016-05-01

    According to BPLS (Badan Penanggulangan Lumpur Sidoarjo) which is the Sidoarjo Mudflow Management Agency, land subsidence occurred in Porong, Sidoarjo was caused by the rocks bearing capacity decreasing which led by the mud outpouring since 2006. The subsidence varies in many ways depends on the radius of location from the mud flow center point and the geological structure. One of the most efficient technologies to monitor this multi temporal phenomenon is using the Synthetic Aperture Radar (SAR) as an applicative Spatial Geodesy. This study used 4 (four) times series L-Band ALOS PALSAR from 2008 to 2011 Fine Beam Single data (February 2008, January 2009 and February 2010 and January 2011) which then processed by the Differential SAR Interferometry (DInSAR) method to obtain the deformation vector at a radius of 1.5 km from the center of mudflow. The result showed that there was a significant subsidence which annually occurred on southern and western area of Sidoarjo mud flow. The deformation vector that occurred in the year 2008-2011 was up to 20 cm/year or 0.05 cm/day. For verification purpose, we also compared the result obtained from the SAR detection with the data measured by Global Position System (GPS) and some deformation monitoring results obtained from another researchs. The comparison showed a correlation that the subsidence occurred on the same location.

  9. A NOVEL SVM FOR GROUND PENETRATING SYNTHETIC APERTURE RADAR LANDMINE DETECTION

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The use of vehicle- or air-borne Ground Penetrating Synthetic Aperture Radar (GPSAR) to quickly detect landmines over large areas is becoming a trend. However, producing too many false alarms in GPSAR landmine detection is a major challenge in practical applications of GPSAR. Support Vector Machine (SVM), employing structural risk minimization theory, does not need large amounts of training data, which makes it suitable for solving the landmine detection problem. In this paper, a novel SVM with a hypersphere instead of a hyperplane classification boundary is proposed for landmine detection in GPSAR. The HyperSphere-SVM (HS-SVM) can be trained with both landmine and clutter data, or with landmine data only, which are called the two-class HS-SVM and the one-class HS-SVM, respectively. The HS-SVM has better generalization capability than the traditional HyperPlane-SVM (HP-SVM) with respect to varying operating conditions. Quantitative comparisons have been made using real data collected with the rail-GPSAR landmine detection system, which show that both the two-class and the one-class HS-SVMs have better detection performance than the HP-SVM.

  10. Unsupervised polarimetric synthetic aperture radar image classification based on sketch map and adaptive Markov random field

    Science.gov (United States)

    Shi, Junfei; Li, Lingling; Liu, Fang; Jiao, Licheng; Liu, Hongying; Yang, Shuyuan; Liu, Lu; Hao, Hongxia

    2016-04-01

    Markov random field (MRF) model is an effective tool for polarimetric synthetic aperture radar (PolSAR) image classification. However, due to the lack of suitable contextual information in conventional MRF methods, there is usually a contradiction between edge preservation and region homogeneity in the classification result. To preserve edge details and obtain homogeneous regions simultaneously, an adaptive MRF framework is proposed based on a polarimetric sketch map. The polarimetric sketch map can provide the edge positions and edge directions in detail, which can guide the selection of neighborhood structures. Specifically, the polarimetric sketch map is extracted to partition a PolSAR image into structural and nonstructural parts, and then adaptive neighborhoods are learned for two parts. For structural areas, geometric weighted neighborhood structures are constructed to preserve image details. For nonstructural areas, the maximum homogeneous regions are obtained to improve the region homogeneity. Experiments are taken on both the simulated and real PolSAR data, and the experimental results illustrate that the proposed method can obtain better performance on both region homogeneity and edge preservation than the state-of-the-art methods.

  11. Detection of Built-Up Areas Using Polarimetric Synthetic Aperture Radar Data and Hyperspectral Image

    Science.gov (United States)

    Bordbari, R.; Maghsoudi, Y.; Salehi, M.

    2015-12-01

    Polarimetric synthetic aperture radar (POLSAR) is an advantageous data for information extraction about objects and structures by using the wave scattering and polarization properties. Hyperspectral remote sensing exploits the fact that all materials reflect, absorb, and emit electromagnetic energy, at specific wavelengths, in distinctive patterns related to their molecular composition. As a result of their fine spectral resolution, Hyperspectral image (HIS) sensors provide a significant amount of information about the physical and chemical composition of the materials occupying the pixel surface. In target detection applications, the main objective is to search the pixels of an HSI data cube for the presence of a specific material (target). In this research, a hierarchical constrained energy minimization (hCEM) method using 5 different adjusting parameters has been used for target detection from hyperspectral data. Furthermore, to detect the built-up areas from POLSAR data, building objects discriminated from surrounding natural media presented on the scene using Freeman polarimetric target decomposition (PTD) and the correlation coefficient between co-pol and cross-pol channels. Also, target detection method has been implemented based on the different polarization basis for using the more information. Finally a majority voting method has been used for fusing the target maps. The polarimetric image C-band SAR data acquired by Radarsat-2, over San Francisco Bay area was used for the evaluation of the proposed method.

  12. Detection and suppression of narrow band RFI for synthetic aperture radar imaging

    Directory of Open Access Journals (Sweden)

    Yang Lin

    2015-08-01

    Full Text Available Radio frequency interference (RFI is becoming more and more frequently, which makes it an important issue in SAR imaging. RFI presented in synthetic aperture radar either on purpose or inadvertent will distort the useful SAR echoes, thus degrade the SAR image quality. To resolve this issue, a long time study was carried out to study the characteristic of the RFI through the RFI-affected spaceborne and airborne SAR data. Based on the narrow band nature of RFI, this paper proposes a new process which contains both RFI detection and RFI suppression. A useful subband spectral kurtosis detector is first used to detect RFI, and then its results are used for RFI suppression. The proposed process has two advantages: one is the economization on the compute time for unnecessary interference suppression when no RFI existed; the other is improving the performance of the suppression method with knowing the exact position where RFI is. Moreover, the previous RFI suppression method—subband spectral cancelation (SSC is supplemented and perfected. The subband division step is also elaborated detail in this paper. The experiment results show that the subband spectral kurtosis detector exhibits good performance in recognizing both weak and narrow-band RFI. In addition, the validity of the SSC method with subband spectral kurtosis detector is also validated on the real SAR echoes.

  13. Optimal waveform-based clutter suppression algorithm for recursive synthetic aperture radar imaging systems

    Science.gov (United States)

    Zhu, Binqi; Gao, Yesheng; Wang, Kaizhi; Liu, Xingzhao

    2016-04-01

    A computational method for suppressing clutter and generating clear microwave images of targets is proposed in this paper, which combines synthetic aperture radar (SAR) principles with recursive method and waveform design theory, and it is suitable for SAR for special applications. The nonlinear recursive model is introduced into the SAR operation principle, and the cubature Kalman filter algorithm is used to estimate target and clutter responses in each azimuth position based on their previous states, which are both assumed to be Gaussian distributions. NP criteria-based optimal waveforms are designed repeatedly as the sensor flies along its azimuth path and are used as the transmitting signals. A clutter suppression filter is then designed and added to suppress the clutter response while maintaining most of the target response. Thus, with fewer disturbances from the clutter response, we can generate the SAR image with traditional azimuth matched filters. Our simulations show that the clutter suppression filter significantly reduces the clutter response, and our algorithm greatly improves the SINR of the SAR image based on different clutter suppression filter parameters. As such, this algorithm may be preferable for special target imaging when prior information on the target is available.

  14. On the detection of crevasses in glacial ice with synthetic-aperture radar.

    Energy Technology Data Exchange (ETDEWEB)

    Brock, Billy C.

    2010-02-01

    The intent of this study is to provide an analysis of the scattering from a crevasse in Antarctic ice, utilizing a physics-based model for the scattering process. Of primary interest is a crevasse covered with a snow bridge, which makes the crevasse undetectable in visible-light images. It is demonstrated that a crevasse covered with a snow bridge can be visible in synthetic-aperture-radar (SAR) images. The model of the crevasse and snow bridge incorporates a complex dielectric permittivity model for dry snow and ice that takes into account the density profile of the glacier. The surface structure is based on a fractal model that can produce sastrugi-like features found on the surface of Antarctic glaciers. Simulated phase histories, computed with the Shooting and Bouncing Ray (SBR) method, are processed into SAR images. The viability of the SBR method for predicting scattering from a crevasse covered with a snow bridge is demonstrated. Some suggestions for improving the model are given.

  15. A parameter inversion for sea bridge based on high-resolution polarimetric synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    LIU Genwang; ZHANG Jie; ZHANG Xi; MENG Junmin; WANG Guoyu

    2016-01-01

    Each reflection return of a bridge over water is displayed as wide stripe in a high-resolution synthetic aperture radar (SAR) image, which lead to difficulties in a parameter inversion. Therefore, a method of bridge parameter inversion is proposed for high-resolution full polarimetric SAR (PolSAR). First, the single, double and triple-bounce returns from each component of the bridge are distinguished by the polarization scattering features. Then the reasons which lead to the backscatter echoes of the bridge over water being displayed as stripes are analyzed, using a principle of microwave reflection, as well as an extraction method for each reflection return, and a parameter retrieval method is obtained. Finally, the parameters of the bridge, including the height (top and bottom surfaces of the sea bridge), width, thickness, span, and height of the bridge tower, are retrieved using full polarimetric AIRSAR data. When a comparison of the measured data is completed, the results indicate that the proposed method can invert the parameters with a high accuracy, and that the inversion error of the bridge height (bottom surface) is only 1.3%. Moreover, the results also show that for the high-resolution SAR, the C and L-band images have the same ability in regards to parameter retrieval.

  16. An extended chirp scaling algorithm for spaceborne sliding spotlight synthetic aperture radar imaging

    Institute of Scientific and Technical Information of China (English)

    Guo Jiao; Xu Youshuan; Fu Longsheng

    2014-01-01

    A system impulse response with low sidelobes is critical in synthetic aperture radar (SAR) images because sidelobes contribute to noise and interfere with nearby scatterers. However, the conventional tricks of sidelobe suppression are unable to be exactly applied to the case of space-borne sliding spotlight SAR due to great azimuth shifts in both time and frequency domains. In this paper, an extended chirp scaling algorithm is presented for spaceborne sliding spotlight SAR data imaging. The proposed algorithm firstly uses the spectral analysis (SPECAN) technique to avoid the azimuth spectrum folding effect and then employs the chirp scaling (CS) algorithm to achieve data focusing, i.e., the so-called two-step approach. To suppress the sidelobe level, an efficient strategy for the azimuth spectral weighting which only involves matrix multiplications and short fast Fourier transformations (FFTs) is proposed, which is a post-process executed on the focused SAR image and particularly simple to be implemented. The SAR image processed by the proposed extended CS algorithm is very precise and perfectly phase-preserving. In the end, computer simulation results verify the analysis and confirm the validity of the proposed algorithm.

  17. Polarimetric synthetic aperture radar image classification using fuzzy logic in the H/α-Wishart algorithm

    Science.gov (United States)

    Zhu, Teng; Yu, Jie; Li, Xiaojuan; Yang, Jie

    2015-01-01

    To solve the problem that the H/α-Wishart unsupervised classification algorithm can generate only inflexible clusters due to arbitrarily fixed zone boundaries in the clustering processing, a refined fuzzy logic based classification scheme called the H/α-Wishart fuzzy clustering algorithm is proposed in this paper. A fuzzy membership function was developed for the degree of pixels belonging to each class instead of an arbitrary boundary. To devise a unified fuzzy function, a normalized Wishart distance is proposed during the clustering step in the new algorithm. Then the degree of membership is computed to implement fuzzy clustering. After an iterative procedure, the algorithm yields a classification result. The new classification scheme is applied to two L-band polarimetric synthetic aperture radar (PolSAR) images and an X-band high-resolution PolSAR image of a field in LingShui, Hainan Province, China. Experimental results show that the classification precision of the refined algorithm is greater than that of the H/α-Wishart algorithm and that the refined algorithm performs well in differentiating shadows and water areas.

  18. Application of Multifractal Analysis to Segmentation of Water Bodies in Optical and Synthetic Aperture Radar Satellite Images

    OpenAIRE

    Martin, Victor Manuel San; Figliola, Alejandra

    2016-01-01

    A method for segmenting water bodies in optical and synthetic aperture radar (SAR) satellite images is proposed. It makes use of the textural features of the different regions in the image for segmentation. The method consists in a multiscale analysis of the images, which allows us to study the images regularity both, locally and globally. As results of the analysis, coarse multifractal spectra of studied images and a group of images that associates each position (pixel) with its correspondin...

  19. Soil Moisture Estimation in South-Eastern New Mexico Using High Resolution Synthetic Aperture Radar (SAR) Data

    OpenAIRE

    A.K.M. Azad Hossain; Greg Easson

    2016-01-01

    Soil moisture monitoring and characterization of the spatial and temporal variability of this hydrologic parameter at scales from small catchments to large river basins continues to receive much attention, reflecting its critical role in subsurface-land surface-atmospheric interactions and its importance to drought analysis, irrigation planning, crop yield forecasting, flood protection, and forest fire prevention. Synthetic Aperture Radar (SAR) data acquired at different spatial resolutions h...

  20. Necessity to adapt land use and land cover classification systems to readily accept radar data

    Science.gov (United States)

    Drake, B.

    1977-01-01

    A hierarchial, four level, standardized system for classifying land use/land cover primarily from remote-sensor data (USGS system) is described. The USGS system was developed for nonmicrowave imaging sensors such as camera systems and line scanners. The USGS system is not compatible with the land use/land cover classifications at different levels that can be made from radar imagery, and particularly from synthetic-aperture radar (SAR) imagery. The use of radar imagery for classifying land use/land cover at different levels is discussed, and a possible revision of the USGS system to more readily accept land use/land cover classifications from radar imagery is proposed.

  1. Performance Investigation on Scan-On-Receive and Adaptive Digital Beam-Forming for High-Resolution Wide-Swath Synthetic Aperture Radar

    OpenAIRE

    Bordoni, Federica; Younis, Marwan; Makhoul Varona, Eduardo; Gebert, Nicolas; Krieger, Gerhard

    2009-01-01

    The work investigates the performance of the Smart Multi-Aperture Radar Technique (SMART) Synthetic Aperture Radar (SAR) system for high-resolution wide-swath imaging based on Scan-on-Receive (SCORE) algorithm for receive beam steering. SCORE algorithm works under model mismatch conditions in presence of topographic height. A study on the potentiality of an adaptive approach for receive beam steering based on spatial spectral estimation is presented. The impact of topographic height on SCORE ...

  2. Optimization Of Wind and Wave Fields for Typical Marine Radar Using Synthetic Aperture Method

    OpenAIRE

    M.N. V. Pavan Kumar; Debajyoti Chatterjee; Nekkala Sateesh; Abhijit Dey; Pavan Kumar

    2012-01-01

    This paper deals with the use of the wave-radar for sea-state monitoring. The radar used here is popular as marine radar. SEA STATE monitoring by X-band Mare Radar system is becoming increasingly interesting, also due to its spatial resolution, which is much higher than the resolution of the relatively more common high-frequency (HF) coastal radars. In addition, compared to HF radar, Xband radar systems offer an improved operational flexibility; due to their small dimension, low weight, and e...

  3. Gulf of Mexico Ecological Forecasting - Atlantic Bluefin Tuna Population Assessment and Management using Synthetic Aperture Radar (SAR) Data

    Science.gov (United States)

    Laygo, K.; Jones, I.; Huerta, J.; Holt, B.

    2010-12-01

    Atlantic Bluefin Tuna (Thunnus thynnus) is one of the largest vertebrates in the world and is in high demand in sushi markets. It is a highly political species and is managed internationally by the International Commission for the Conservation of Atlantic Tuna. The Gulf of Mexico and the Mediterranean Sea are the only two known spawning sites in the world. However, there is a large variance in estimates of adult Atlantic Tuna spawning. This research focuses on extending Earth science research results to existing decision-making systems, National Oceanic and Atmospheric Administration (NOAA) and the National Marine Fisheries Service (NMFS)for population assessment and management of Atlantic Bluefin Tuna. The research team is a multi-sector and multi-disciplinary team composed of government (NOAA_NMFS), academic (University of South Florida Institute for Marine Remote Sensing) and commercial (Roffer’s Ocean Fishing Forecasting Service, Inc.) institutions. Their goal is to reduce the variance in the estimates of adult Bluefin Tuna spawning stock abundance in the Gulf of Mexico (GOM). Therefore, this paper will be derived from the innovative use of several earth orbiting satellites focusing on the use of synthetic aperture radar (SAR) data to identify Sargassum, which is a floating marine algae that may be relevant to the presence of Bluefin Tuna aggregations. The SAR imagery will be examined in combination with MODIS and MERIS Chlorophyll-a products to detect fine-scale surface current shear, eddy and frontal features, as well as biological slicks due to the presence of Sargassum. In addition, wind records from NOAA buoy data will be studied to analyze wind patterns in the Gulf of Mexico. The fine-resolution, all-weather capabilities of SAR provide a valuable complement to optical/IR sensors, which are often impacted by cloud cover. This study will provide an assessment of whether or not SAR can contribute to decision support efforts relevant to commercial fisheries

  4. An Empirical Assessment of Temporal Decorrelation Using the Uninhabited Aerial Vehicle Synthetic Aperture Radar over Forested Landscapes

    Directory of Open Access Journals (Sweden)

    Michelle Hofton

    2012-04-01

    Full Text Available We present an empirical assessment of the impact of temporal decorrelation on interferometric coherence measured over a forested landscape. A series of repeat-pass interferometric radar images with a zero spatial baseline were collected with UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar, a fully polarimetric airborne L-band radar system. The dataset provided temporal separations of 45 minutes, 2, 7 and 9 days. Coincident airborne lidar and weather data were collected. We theoretically demonstrate that UAVSAR measurement accuracy enables accurate quantification of temporal decorrelation. Data analysis revealed precipitation events to be the main driver of temporal decorrelation over the acquisition period. The experiment also shows temporal decorrelation increases with canopy height, and this pattern was found consistent across forest types and polarization.

  5. Lagrangian modelling of ocean surface waves and synthetic aperture radar wave measurements

    Energy Technology Data Exchange (ETDEWEB)

    Fouques, Sebastien

    2005-07-01

    The present thesis is concerned with the estimation of the ocean wave spectrum from synthetic aperture radar imaging and the modelling of ocean surface waves using the Lagrangian formalism. The first part gives a short overview of the theories of ocean surface waves and synthetic aperture radar (SAR) whereas the second part consists of five independent publications. The first two articles investigate the influence of the radar backscatter model on the SAR imaging of ocean waves. In Article I, Monte Carlo simulations of SAR images of the ocean surface are carried out using a nonlinear backscatter model that include both specular reflection and Bragg scattering and the results are compared to simulations from the classical Hasselmann integral transform (Hasselmann and Hasselmann, 1991). It is shown that nonlinearities in the backscatter model strongly influence the imaging of range-travelling waves and that the former can suppress the range-splitting effect (Bruning et al., 1988). Furthermore, in Article II a database of Envisat-ASAR Wave Mode products co-located with directional wave spectra from the numerical model WAM and which contains range-travelling wave cases only, is set up. The WAM spectra are used as input to several ocean-to-SAR integral transforms, with various real aperture radar (RAR) models and the obtained SAR image cross-spectra are compared to the Envisat-ASAR observations. A first result is that the use of a linear backscatter model leads to a high proportion of non-physical negative backscatter values in the RAR image, as suggested by Schulz-Stellenfleth (2001). Then, a comparison between the observed SAR cross-spectra and the ones simulated through Hasselmann's integral transform reveals that only twenty percents of the observations show a range-splitting effect as strong as in the simulations. A much better agreement is obtained when using the integral transform by Schulz-Stellenfleth (2003), which is based on a nonlinear hackscatter model

  6. Motion estimation and imaging of complex scenes with synthetic aperture radar

    International Nuclear Information System (INIS)

    We study synthetic aperture radar (SAR) imaging and motion estimation of complex scenes consisting of stationary and moving targets. We use the classic SAR setup with a single antenna emitting signals and receiving the echoes from the scene. The known motion estimation methods for SAR work only in simple cases, with one or a few targets in the same motion. We propose to extend the applicability of these methods to complex scenes, by complementing them with a data pre-processing step intended to separate the echoes from the stationary targets and the moving ones. We present two approaches. The first is an iteration designed to subtract the echoes from the stationary targets one by one. This approach first estimates the location of each stationary target from a preliminary image, and then uses the location to define a filter that removes the corresponding target’s echo from the data. The second approach is based on the robust principal component analysis (PCA) method. The key observation is that with appropriate pre-processing and windowing, the discrete samples of the stationary target echoes form a low-rank matrix, whereas the samples of a few moving target echoes form a high-rank sparse matrix. The robust PCA method is designed to separate the low rank from the sparse part, and thus can be used for the SAR data separation. We present a brief analysis of the two methods and explain how they can be combined to improve the data separation for extended and complex imaging scenes. We also assess the performance of the methods with extensive numerical simulations. (paper)

  7. Quantifying methane ebullition in thermokarst lakes with space borne synthetic aperture radar (SAR)

    Science.gov (United States)

    Engram, M. J.; Walter Anthony, K.; Meyer, F. J.; Grosse, G.

    2011-12-01

    Northern high latitude wetlands and thermokarst lakes in permafrost regions have been identified as strong sources for methane (CH4), a powerful greenhouse gas. Quantifying the spatial distribution and magnitude of CH4 sources in these regions has become increasingly important in the current scenario of global warming and amidst concerns of partial release of the large permafrost soil carbon pool through thawing by thermokarst lakes. Ebullition (bubbling) is an important mode of CH4 emission from thermokarst lakes to the atmosphere. However, due to its sporadic behavior, large uncertainties remain in estimating the magnitude of ebullition emissions from lakes. Synthetic Aperture Radar (SAR) remote sensing of lake ice is a potentially valuable tool to constrain bottom-up estimates of lake ebullition in regions where lake ice forms. Here we explored various SAR imaging parameters as they correlate to field measurements of CH4 ebullition bubbles in the ice of ten thermokarst lakes on the northern Seward Peninsula, Alaska. We found that ebullition bubbles trapped in frozen lakes were strongly correlated with L-band single polarized horizontal (HH) SAR (R2 = 0.70, P = 0.002) and with the 'roughness' component of a classic Pauli decomposition of PALSAR L-band quad-polarized signal (R2 = 0.77, P = 0.001). We found no such correlation with ERS-2 C-band single polarized vertical (VV) SAR. We present the results of our single-pol and quad-pol SAR geospatial analysis, a discussion of probable scattering mechanisms of ebullition bubbles in frozen thermokarst lakes and our recommendation for the optimal season for SAR observation. Our results indicate that calibrated L-band SAR could be a valuable tool for estimating methane ebullition in lakes on a regional scale by evaluating the backscatter intensity from early winter lake ice.

  8. Coal mining induced land subsidence monitoring using multiband spaceborne differential interferometric synthetic aperture radar data

    Science.gov (United States)

    Yue, Huanyin; Liu, Guang; Guo, Huadong; Li, Xinwu; Kang, Zhizhong; Wang, Runfeng; Zhong, Xuelian

    2011-01-01

    The differential interferometric synthetic aperture radar (SAR)(DInSAR) technique has been applied to the earth surface deformation monitoring in many areas. In this paper, the DInSAR technique is used to process the spaceborne SAR data including C band ENVISAT ASAR, L band JERS SAR, and ALOS PALSAR data to derive the temporal land subsidence information in the Fengfeng coal mine area, Hebei province in China. Since JERS and ALOS do not have precise orbit, an orbit adjustment must be accomplished before the DInSAR interferogram was formed. Twenty-three differential interferograms are derived to show the temporal change of the land subsidence range and position. At the acquisition time of ENVISAT ASAR, the leveling in the Dashucun coal mine in Fengfeng area was carried, the historical excavation data in 8 coal mines in Fengfeng area from 1992 to 2007 were collected as well. In our analysis, the DInSAR results are compared with leveling data and historical excavation data. The comparison results show the DInSAR subsidence results are consistent with the leveling results and the historical excavation data, and the L band DInSAR shows more advantages than C band in the coal mining induced subsidence monitoring in a rural area. The feasibility and limitations in coal mining induced subsidence monitoring with DInSAR are analyzed, and the possibility of underground mining activity monitoring by spaceborne InSAR data is evaluated. The experimental results show that both C and L band can accomplish monitoring mining area subsidence, but C band has more restricted conditions of its perpendicular baseline. In order to get a satisfactory outcome in mining area subsidence by the DInSAR method, the time series of SAR images of every visit and SAR deformation interferograms should be archived.

  9. Iceberg and ship detection and classification in single, dual and quad polarized synthetic aperture radar

    Science.gov (United States)

    Howell, Carl

    Iceberg and ship identification in satellite synthetic aperture radar (SAR) data is an essential part of offering an operational iceberg surveillance program. Identification here refers to detection of ocean SAR targets and then classification of these targets as iceberg, ship, or unknown. Maximizing the detection and minimizing incorrect classification of iceberg and ship targets are required. Because coarser resolution satellite SAR data is at times not as intuitive as satellite optical data for manual human interpreted target classification, this process can be labor intensive, subjective, and error prone. Therefore, it is desired that an automated method for iceberg or ship identification be implemented. The methodology investigated here follows a well known standard in supervised pattern recognition, the maximum likelihood-quadratic discriminant function. The goal here in this thesis is to build class models from known iceberg and ship targets. Each class model is based on features that describe targets such as brightness, texture, and shape. Based on these descriptors as training input into the discriminant functions, future unknown targets can be compared with the class model for best fit. The best fit (or minimum distance) is used to assign class status for these unknown targets. One major consideration when using this type of pattern recognition approach is feature selection. Feature selection is based on the notion that some subset (subspace) of the descriptive metrics will lead to improved classification accuracy when comparing discriminant functions. Sequential forward selection and variants of exhaustive search algorithms are implemented and compared. RADARSAT-1, ENVSIAT AP (HH/HV), and EMISAR SAR iceberg and ship targets are used for algorithm training, feature selection, and performance estimation.

  10. Sequential Ensembles Tolerant to Synthetic Aperture Radar (SAR Soil Moisture Retrieval Errors

    Directory of Open Access Journals (Sweden)

    Ju Hyoung Lee

    2016-04-01

    Full Text Available Due to complicated and undefined systematic errors in satellite observation, data assimilation integrating model states with satellite observations is more complicated than field measurements-based data assimilation at a local scale. In the case of Synthetic Aperture Radar (SAR soil moisture, the systematic errors arising from uncertainties in roughness conditions are significant and unavoidable, but current satellite bias correction methods do not resolve the problems very well. Thus, apart from the bias correction process of satellite observation, it is important to assess the inherent capability of satellite data assimilation in such sub-optimal but more realistic observational error conditions. To this end, time-evolving sequential ensembles of the Ensemble Kalman Filter (EnKF is compared with stationary ensemble of the Ensemble Optimal Interpolation (EnOI scheme that does not evolve the ensembles over time. As the sensitivity analysis demonstrated that the surface roughness is more sensitive to the SAR retrievals than measurement errors, it is a scope of this study to monitor how data assimilation alters the effects of roughness on SAR soil moisture retrievals. In results, two data assimilation schemes all provided intermediate values between SAR overestimation, and model underestimation. However, under the same SAR observational error conditions, the sequential ensembles approached a calibrated model showing the lowest Root Mean Square Error (RMSE, while the stationary ensemble converged towards the SAR observations exhibiting the highest RMSE. As compared to stationary ensembles, sequential ensembles have a better tolerance to SAR retrieval errors. Such inherent nature of EnKF suggests an operational merit as a satellite data assimilation system, due to the limitation of bias correction methods currently available.

  11. Detection of explosive hazards using spectrum features from forward-looking ground penetrating radar imagery

    Science.gov (United States)

    Farrell, Justin; Havens, Timothy C.; Ho, K. C.; Keller, James M.; Ton, Tuan T.; Wong, David C.; Soumekh, Mehrdad

    2011-06-01

    Buried explosives have proven to be a challenging problem for which ground penetrating radar (GPR) has shown to be effective. This paper discusses an explosive hazard detection algorithm for forward looking GPR (FLGPR). The proposed algorithm uses the fast Fourier transform (FFT) to obtain spectral features of anomalies in the FLGPR imagery. Results show that the spectral characteristics of explosive hazards differ from that of background clutter and are useful for rejecting false alarms (FAs). A genetic algorithm (GA) is developed in order to select a subset of spectral features to produce a more generalized classifier. Furthermore, a GA-based K-Nearest Neighbor probability density estimator is employed in which targets and false alarms are used as training data to produce a two-class classifier. The experimental results of this paper use data collected by the US Army and show the effectiveness of spectrum based features in the detection of explosive hazards.

  12. Shadow enhancement in synthetic aperture sonar imagery for improved target classification

    NARCIS (Netherlands)

    Sabel, J.C.; Groen, J.; Quesson, B.A.J.

    2005-01-01

    The acoustic shadow of a target is a strong classification clue in naval mine hunting. A shadow of bottom targets appears at relatively short ranges (≤ about 200 m) in high resolution images from sidescan or synthetic aperture sonar (SAS), against a background of sea floor reverberation. In SAS howe

  13. Satellite microwave remote sensing of North Eurasian inundation dynamics: development of coarse-resolution products and comparison with high-resolution synthetic aperture radar data

    International Nuclear Information System (INIS)

    Wetlands are not only primary producers of atmospheric greenhouse gases but also possess unique features that are favourable for application of satellite microwave remote sensing to monitoring their status and trend. In this study we apply combined passive and active microwave remote sensing data sets from the NASA sensors AMSR-E and QuikSCAT to map surface water dynamics over Northern Eurasia. We demonstrate our method on the evolution of large wetland complexes for two consecutive years from January 2006 to December 2007. We apply river discharge measurements from the Ob River along with land surface runoff simulations derived from the Pan-Arctic Water Balance Model during and after snowmelt in 2006 and 2007 to interpret the abundance of widespread flooding along the River Ob in early summer of 2007 observed in the remote sensing products. The coarse-resolution, 25 km, surface water product is compared to a high-resolution, 30 m, inundation map derived from ALOS PALSAR (Advanced Land Observation Satellite phased array L-band synthetic aperture radar) imagery acquired for 11 July 2006, and extending along a transect in the central Western Siberian Plain. We found that the surface water fraction derived from the combined AMSR-E/QuikSCAT data sets closely tracks the inundation mapped using higher-resolution ALOS PALSAR data.

  14. Polluter identification with spaceborne radar imagery, AIS and forward drift modeling.

    Science.gov (United States)

    Longépé, N; Mouche, A A; Goacolou, M; Granier, N; Carrere, L; Lebras, J Y; Lozach, P; Besnard, S

    2015-12-30

    This study defines and assesses a new operational concept to identify the origin of pollution at sea, based on Synthetic Aperture Radar, Automatic Identification System, and a forward drift model. As opposed to traditional methodologies where the SAR detected pollution is backtracked in the past, our approach assumes that all the vessels pollute all along their way. Based on all the AIS data flows, the forward-tracked simulated pollutions are then compared to the detected pollution, and the potential polluter can be finally identified. Case studies are presented to showcase its usefulness in a variety of maritime situations with a focus on orphan pollutions in a dense traffic area. Out of the identification of the suspected polluters, the age and eventually the type of the pollution can be retrieved. PMID:26490412

  15. Study of Effects of Flat Surface Assumption to Synthetic Aperture Radar Time-domain Algorithms Imaging Quality

    Directory of Open Access Journals (Sweden)

    Lin Shi-bin

    2012-08-01

    Full Text Available Time-domain algorithms have great application prospect in Ultra Wide Band Synthetic Aperture Radar (UWB SAR imaging for its advantages such as perfect focusing and perfect motion compensation. We could adopt the flat surface assumption to simplify the imaging geometric model, when undulating terrain is imaged using time-domain algorithms. Nevertheless, the flat surface assumption leads to geometric errors, thereby affecting the imaging results. This paper studies the effects of this assumption on time-domain imaging algorithms, points out that it leads to position offset problem in the case of linear aperture, and it even leads to target defocusing problem in the case of non-linear aperture. The expression of position offset is given in this paper, as well as the restriction of the maximal offset of the non-linear aperture and the maximum elevation of the area in order to focus the targets. The conclusions are validated by simulated data, which is processed by one kind of time-domain algorithms, namely Back Projection (BP algorithm.

  16. Geometric ortho-rectification and generation of sigma(0) image products from multiple incidence synthetic aperture radar images

    Science.gov (United States)

    Curlander, James; Leberl, Franz; Kruse, Fred

    1992-01-01

    The results of the first phase of a cooperative effort in geometric orthorectification and generation of sigma(0) images of multiple incidence SAR images are presented. The geometric accuracy of the final image products is approximately 18 m or 1.5 pixels. A method for registering radar imagery collected from an airborne platform to an existing digital elevation model despite the effects of unmodeled variations in the flight path of the platform is demonstrated. The results indicate the requirements for a more detailed digital elevation model.

  17. The Synthetic Aperture Radar Science Data Processing Foundry Concept for Earth Science

    Science.gov (United States)

    Rosen, P. A.; Hua, H.; Norton, C. D.; Little, M. M.

    2015-12-01

    Since 2008, NASA's Earth Science Technology Office and the Advanced Information Systems Technology Program have invested in two technology evolutions to meet the needs of the community of scientists exploiting the rapidly growing database of international synthetic aperture radar (SAR) data. JPL, working with the science community, has developed the InSAR Scientific Computing Environment (ISCE), a next-generation interferometric SAR processing system that is designed to be flexible and extensible. ISCE currently supports many international space borne data sets but has been primarily focused on geodetic science and applications. A second evolutionary path, the Advanced Rapid Imaging and Analysis (ARIA) science data system, uses ISCE as its core science data processing engine and produces automated science and response products, quality assessments and metadata. The success of this two-front effort has been demonstrated in NASA's ability to respond to recent events with useful disaster support. JPL has enabled high-volume and low latency data production by the re-use of the hybrid cloud computing science data system (HySDS) that runs ARIA, leveraging on-premise cloud computing assets that are able to burst onto the Amazon Web Services (AWS) services as needed. Beyond geodetic applications, needs have emerged to process large volumes of time-series SAR data collected for estimation of biomass and its change, in such campaigns as the upcoming AfriSAR field campaign. ESTO is funding JPL to extend the ISCE-ARIA model to a "SAR Science Data Processing Foundry" to on-ramp new data sources and to produce new science data products to meet the needs of science teams and, in general, science community members. An extension of the ISCE-ARIA model to support on-demand processing will permit PIs to leverage this Foundry to produce data products from accepted data sources when they need them. This paper will describe each of the elements of the SAR SDP Foundry and describe their

  18. Use of interferometric techniques for detecting subsidence in the oil fields of Kuwait using Synthetic Aperture Radar Data

    International Nuclear Information System (INIS)

    Subsidence in Burgan oil field of Kuwait has been studied by Interferometric technique using Synthetic Aperture Radar data. Repeat pass Interferometry is applied to the study area that accounts for infinitesimal changes in the topographic elevations. Subsidence of about 27 mm over a period of 3 years was estimated in Burgan oil field area. The study is significant since continued subsidence may result in reduction of porosity of host formation and may activate the sub-surface geological structures, which can compromise the integrity of the reservoir seal, leading to migration of hydrocarbons to other formations and areas

  19. Real Aperture Radar interferometry as a tool for buildings vibration monitoring: Limits and potentials from an experimental study

    Science.gov (United States)

    Luzi, Guido; Monserrat, Oriol; Crosetto, Michele

    2012-06-01

    In the last decade several researchers have dealt with the potential of radar interferometry as a remote sensing tool able to provide measurements of vibrations of large structures. More recently the technique has been consolidated thanks to the recent introduction on the market of specifically devoted radar instruments. Exploiting the interferometric capability of coherent radar, successful monitoring of bridges, towers and wind turbine powers has been achieved. This technique allowed looking at the frequency behaviour of civil structures and estimating their amplitude of displacement in the order of fraction of millimetres. The activity here described reports the results of an experimental investigation aimed at evaluating the effectiveness of a coherent Real-Aperture-Radar sensor to estimate the vibration of buildings in an urban environment, through an ambient vibration testing, where the expected amplitude vibration spans within a few to some tens of microns. Critical aspects affecting the retrieval of this information are here discussed, on the basis of some experimental data collected in the last year with a microwave interferometer working at Ku band and available on the market. Preliminary results are shown and suggestions related to the measurement procedures are discussed.

  20. Road Extraction and Network Building from Synthetic Aperture Radar Images using A-Priori Information

    NARCIS (Netherlands)

    Dekker, R.J.

    2008-01-01

    This paper describes a method for the extraction of road networks from radar images. Three phases can be distinguished: (1) detection of road lines, (2) network building, and (3) network fusion. The method has been demonstrated on two radar images, one urban and one rural. Despite the differences, t

  1. Development of an Airborne Ka-band FMCW Synthetic Aperture Radar

    NARCIS (Netherlands)

    De Wit, J.J.M.

    2005-01-01

    In the field of airborne earth observation there is a special interest in lightweight, low cost imaging radars of high resolution. Such radar systems could play an essential role in small-scale earth observation applications such as the monitoring of dikes, watercourses or areas in which gas pipes o

  2. A-Differential Synthetic Aperture Radar Interferometry analysis of a Deep Seated Gravitational Slope Deformation occurring at Bisaccia (Italy).

    Science.gov (United States)

    Di Martire, Diego; Novellino, Alessandro; Ramondini, Massimo; Calcaterra, Domenico

    2016-04-15

    This paper presents the results of an investigation on a Deep Seated Gravitational Slope Deformation (DSGSD), previously only hypothesized by some authors, affecting Bisaccia, a small town located in Campania region, Italy. The study was conducted through the integration of conventional methods (geological-geomorphological field survey, air-photo interpretation) and an Advanced-Differential Interferometry Synthetic Aperture Radar (A-DInSAR) technique. The DSGSD involves a brittle lithotype (conglomerates of the Ariano Irpino Supersynthem) resting over a Structurally Complex Formation (Varycoloured Clays of Calaggio Formation). At Bisaccia, probably as a consequence of post-cyclic recompression phenomena triggered by reiterated seismic actions, the rigid plate made up of conglomeratic sediments resulted to be split in five portions, showing different rates of displacements, whose deformations are in the order of some centimeter/year, thus inducing severe damage to the urban settlement. A-DInSAR techniques confirmed to be a reliable tool in monitoring slow-moving landslides. In this case 96 ENVIronmental SATellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) images, in ascending and descending orbits, have been processed using SUBSOFT software, developed by the Remote Sensing Laboratory (RSLab) group from the Universitat Politècnica de Catalunya (UPC). The DInSAR results, coupled with field survey, supported the analysis of the instability mechanism and confirmed the historical record of the movements already available for the town. PMID:26849321

  3. Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars

    Science.gov (United States)

    Janches, Diego; Heinselman, Craig J.; Chau, Jorge L.; Chandran, Amal; Woodman, Ronald

    2006-07-01

    We report initial results of an effort to model the diurnal and seasonal variability of the meteor rate detected by high power and large aperture (HPLA) radars. The model uses Monte Carlo simulation techniques and at present assumes that most of the detected particles originate from three radiant distributions with the most dominant concentrated around the Earth's apex. The other two sources are centered 80° in ecliptic longitude to each side of the apex and are commonly known as helion and antihelion. To reproduce the measurements, the apex source flux was set to provide ˜70% of the total number of particles while the other ˜30% is provided by the combined contribution of the two remaining sources. The results of the model are in excellent agreement with observed diurnal curves obtained at different seasons and locations using the 430 MHz Arecibo radar in Puerto Rico, the 50 MHz Jicamarca radar in Perú, and the 1.29 GHz Sondrestrom radar in Greenland. To obtain agreement with the observed diurnal and seasonal variability of the meteor rate, an empirical atmospheric filtering effect was introduced in the simulation which prevents meteors with low-elevation radiants (≤20°) from being detected by the radars at mesospheric altitudes. The filtering effect is probably produced by a combination of factors related to the interaction of the meteor with the air molecules such as electron production and/or the ablation at higher altitudes. On the basis of these results we calculate the micrometeor global, diurnal, and seasonal input in the upper atmosphere.

  4. Eye in the sky : radar satellite imagery shows promise as a heavy oil reservoir monitoring tool

    Energy Technology Data Exchange (ETDEWEB)

    Wells, P.

    2010-05-15

    A leading international earth observation company has proposed a solution for ground motion and mapping products to the oil and gas industry, including Alberta's oilsands region. Barcelona-based Altamira Information uses interferometry for synthetic aperture radar (InSAR) technology to detect ground motion with millimetric precision. The radar satellite images are used to better understand the complexities of heavy oil reservoirs. InSAR space borne measurement technology is showing promise as a valuable tool for reservoir monitoring, particularly for enhanced oil recovery (EOR) production and steam-assisted gravity drainage (SAGD) operations. InSAR technology offers advantages and flexibility in providing short-term, seasonal and long-term monitoring. Altamira currently has 5 clients in heavy oil, 2 in Alberta and 3 internationally. Radar satellites continuously orbit on a fixed path around the Earth. Each time that the satellite acquires an image over an oilfield, the image provides an array of values on the distance between the satellite and the points of ground. A new array of distance between the satellite and the same points on ground can be obtained when making another image acquisition over the same area. The difference of distance between points on the ground is calculated using a specific algorithm that compensates for the changes in the satellite position. A map of the displacement between the two dates of the images can thus be obtained. The satellites capture images by recording the travel phase between ground and sensor. When several measurements are available, the difference between measurements indicates ground movement over time. Additional effects, such as atmospheric changes and topographic errors, are calculated and compensated. For an EOR field or SAGD operation, Altamira Information installs artificial corner reflectors to provide reliable and relevant information despite changes in weather conditions. Ground motion monitoring with radar

  5. Development of NASA's Next Generation L-Band Digital Beamforming Synthetic Aperture Radar (DBSAR-2)

    Science.gov (United States)

    Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung-Kuk; Ranson, K. Jon; Marrero, Victor; Yeary, Mark

    2014-01-01

    NASA's Next generation Digital Beamforming SAR (DBSAR-2) is a state-of-the-art airborne L-band radar developed at the NASA Goddard Space Flight Center (GSFC). The instrument builds upon the advanced architectures in NASA's DBSAR-1 and EcoSAR instruments. The new instrument employs a 16-channel radar architecture characterized by multi-mode operation, software defined waveform generation, digital beamforming, and configurable radar parameters. The instrument has been design to support several disciplines in Earth and Planetary sciences. The instrument was recently completed, and tested and calibrated in a anechoic chamber.

  6. Differential synthetic aperture radar interferometry for landslide monitoring: a priori GIS based assessment of feasibility

    Science.gov (United States)

    Plank, S.; Singer, J.; Minet, Ch.; Thuro, K.

    2012-04-01

    In the last two decades differential radar interferometry (D-InSAR) has proven to be a powerful remote sensing technique for detection and deformation monitoring of landslides with an accuracy of a few millimeters. However, due to the inclined imaging geometry, areas with a topographic relief (where landslides usually occur) appear heavily distorted in the radar image. Thereby slopes inclined towards the radar sensor appear shortened (foreshortening) and in extreme even can cause an overlapping of different radar signals (layover effect); slopes oriented away from the radar seem stretched (elongation) or even can be shadowed by a steep mountain (shadowing). These effects limit or even prohibit the use of a radar image for interferometric applications. Besides these geometric distortions, the land cover has great influence on the applicability of differential radar interferometry. For example vegetation-free areas such as buildings and rocks show high coherence values over a long time period (high stability of their backscattering properties), whereas areas covered by vegetation, especially forests, have varying backscattering properties at different times (e.g. due to wind; temporal decorrelation). Areas with high coherence values in the radar interferogram are better suited for D-InSAR applications. To date prior to an investigation using D-InSAR these limiting effects usually are only roughly estimated, sometimes leading to disappointing results when the actual radar images are analyzed. Therefore we present a GIS routine, which based on freely available digital elevation model (DEM) data (SRTM) not only accurately predicts the areas in which layover and shadowing will occur, but also determines the percentage of measurability of the movement of a landslide (portion oriented in radar line of sight) for a given radar acquisition geometry. Additionally land cover classification data (e.g. CORINE) is used to evaluate the influence of the landslide's land cover on D

  7. Research on Synthetic Aperture Laser-radar and Its Application%合成孔径激光雷达研究及应用

    Institute of Scientific and Technical Information of China (English)

    杜汪洋; 吴彦鸿; 屈强

    2007-01-01

    在讨论合成孔径激光雷达(synthetic aperture laser-radar,SAL)概念和原理的基础上,研究了SAL系统研制的关键技术;比较了SAL和合成孔径雷达(synthetic aperture radar,SAR)的优缺点;提出了在军事上利用SAL和SAR技术联合检测军事目标,具有重大的军事和民用意义,最后分析了其优越性.

  8. Partially Adaptive Phased Array Fed Cylindrical Reflector Technique for High Performance Synthetic Aperture Radar System

    Science.gov (United States)

    Hussein, Z.; Hilland, J.

    2001-01-01

    Spaceborne microwave radar instruments demand a high-performance antenna with a large aperature to address key science themes such as climate variations and predictions and global water and energy cycles.

  9. Three-dimensional subsurface imaging synthetic aperture radar (3D SISAR). Final report, September 22, 1993 - September 22, 1996

    International Nuclear Information System (INIS)

    The concept developed under this applied research and development contract is a novel Ground Penetrating Radar system capable of remotely detecting, analyzing, and mapping buried waste containers from a mobile platform. From the testing and analysis performed to date, the 3-D SISAR has achieved the detection, accurate location, and three-dimensional imaging of buried test objects from a stand-off geometry. Tests have demonstrated that underground objects have been located to within 0.1 meter of their actual position. This work validates that the key elements of the approach are performing as anticipated. The stand-off synthetic aperture radar (SAR) methodology has been demonstrated to be a feasible approach as a remote sensing technique. The radar sensor constructed under this project is providing adequate quality data for imaging, and the matched filters have been demonstrated to provide enhanced target detection. Additional work is on-going in the area of underground propagation and scattering phenomena to provide enhanced depth performance, as the current imaging results have been limited to a few feet of depth underground

  10. Three-dimensional subsurface imaging synthetic aperture radar (3D SISAR). Final report, September 22, 1993--September 22, 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    The concept developed under this applied research and development contract is a novel Ground Penetrating Radar system capable of remotely detecting, analyzing, and mapping buried waste containers from a mobile platform. From the testing and analysis performed to date, the 3-D SISAR has achieved the detection, accurate location, and three-dimensional imaging of buried test objects from a stand-off geometry. Tests have demonstrated that underground objects have been located to within 0.1 meter of their actual position. This work validates that the key elements of the approach are performing as anticipated. The stand-off synthetic aperture radar (SAR) methodology has been demonstrated to be a feasible approach as a remote sensing technique. The radar sensor constructed under this project is providing adequate quality data for imaging, and the matched filters have been demonstrated to provide enhanced target detection. Additional work is on-going in the area of underground propagation and scattering phenomena to provide enhanced depth performance, as the current imaging results have been limited to a few feet of depth underground.

  11. Continuous monitoring of biophysical Eucalyptus sp. parameters using interferometric synthetic aperture radar data in P and X bands

    Science.gov (United States)

    Gama, Fábio Furlan; dos Santos, João Roberto; Mura, José Claudio

    2016-04-01

    This work aims to verify the applicability of models obtained using interferometric synthetic aperture radar (SAR) data for estimation of biophysical Eucalyptus saligna parameters [diameter of breast height (DBH), total height and volume], as a method of continuous forest inventory. In order to obtain different digital elevation models, and the interferometric height (Hint) to retrieve the tree heights, SAR surveying was carried out by an airborne interferometric SAR in two frequencies X and P bands. The study area, located in the Brazilian southeast region (S 22°53‧22″/W 45°26‧16″ and S 22°53‧22″/W 45°26‧16″), comprises 128.64 hectares of Eucalyptus saligna stands. The methodological procedures encompassed: forest inventory, topographic surveying, radar mapping, radar processing, and multivariable regression techniques to build Eucalyptus volume, DBH, and height models. The statistical regression pointed out Hint and interferometric coherence as the most important variables for the total height and DBH estimation; for the volume model, however, only the Hint variable was selected. The performance of the biophysical models from the second campaign, two years later (2006), were consistent and its results are very promising for updating annual inventories needed for managing Eucalyptus plantations.

  12. Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach

    Science.gov (United States)

    Zanzi, Luigi; Lualdi, Maurizio

    2010-12-01

    The two-step approach is a fast algorithm for 3D migration originally introduced to process zero-offset seismic data. Its application to monostatic GPR (Ground Penetrating Radar) data is straightforward. A direct extension of the algorithm for the application to bistatic radar data is possible provided that the TX-RX azimuth is constant. As for the zero-offset case, the two-step operator is exactly equivalent to the one-step 3D operator for a constant velocity medium and is an approximation of the one-step 3D operator for a medium where the velocity varies vertically. Two methods are explored for handling a heterogeneous medium; both are suitable for the application of the two-step approach, and they are compared in terms of accuracy of the final 3D operator. The aperture of the two-step operator is discussed, and a solution is proposed to optimize its shape. The analysis is of interest for any NDT application where the medium is expected to be heterogeneous, or where the antenna is not in direct contact with the medium (e.g., NDT of artworks, humanitarian demining, radar with air-launched antennas).

  13. Analysis of Approximations and Aperture Distortion for 3D Migration of Bistatic Radar Data with the Two-Step Approach

    Directory of Open Access Journals (Sweden)

    Luigi Zanzi

    2010-01-01

    Full Text Available The two-step approach is a fast algorithm for 3D migration originally introduced to process zero-offset seismic data. Its application to monostatic GPR (Ground Penetrating Radar data is straightforward. A direct extension of the algorithm for the application to bistatic radar data is possible provided that the TX-RX azimuth is constant. As for the zero-offset case, the two-step operator is exactly equivalent to the one-step 3D operator for a constant velocity medium and is an approximation of the one-step 3D operator for a medium where the velocity varies vertically. Two methods are explored for handling a heterogeneous medium; both are suitable for the application of the two-step approach, and they are compared in terms of accuracy of the final 3D operator. The aperture of the two-step operator is discussed, and a solution is proposed to optimize its shape. The analysis is of interest for any NDT application where the medium is expected to be heterogeneous, or where the antenna is not in direct contact with the medium (e.g., NDT of artworks, humanitarian demining, radar with air-launched antennas.

  14. MOBILE MAPPING BY FMCW SYNTHETIC APERTURE RADAR OPERATING AT 300 GHZ

    OpenAIRE

    S. Palm; Sommer, R; Hommes, A.; N. Pohl; U. Stilla

    2016-01-01

    While optical cameras or laser systems are widely used for mobile mapping low attention was payed for radar systems. Due to new semiconductor technologies, compact and leight weight SAR systems based on the Frequency Modulated Continuous Wave (FMCW) principle in the millimeter wave domain can serve for mobile radar mapping on cars. For mapping of long stripes along roads in close range a special strategy for focusing of SAR images was developed. Hereby local adapted planes for proces...

  15. Integration of differential global positioning system with ultrawideband synthetic aperture radar for forward imaging

    Science.gov (United States)

    Wong, David C.; Bui, Khang; Nguyen, Lam H.; Smith, Gregory; Ton, Tuan T.

    2003-09-01

    The U.S. Army Research Laboratory (ARL), as part of a customer and mission-funded exploratory development program, has been evaluating low-frequency, ultra-wideband (UWB) imaging radar for forward imaging to support the Army's vision for increased mobility and survivability of unmanned ground vehicle missions. As part of the program to improve the radar system and imaging capability, ARL has incorporated a differential global positioning system (DGPS) for motion compensation into the radar system. The use of DGPS can greatly increase positional accuracy, thereby allowing us to improve our ability to focus better images for the detection of small targets such as plastic mines and other concealed objects buried underground. The ability of UWB radar technology to detect concealed objects could provide an important obstacle avoidance capability for robotic vehicles, which would improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U.S. forces. This paper details the integration and discusses the significance of integrating a DGPS into the radar system for forward imaging. It also compares the difference between DGPS and the motion compensation data collected by the use of the original theodolite-based system.

  16. Selective Synthetic Aperture Radar and Panchromatic Image Fusion by Using the à Trous Wavelet Decomposition

    Directory of Open Access Journals (Sweden)

    Youcef Chibani

    2005-08-01

    Full Text Available Synthetic aperture radar (SAR imaging sensor presents an important advantage for the earth change observation independently of weather conditions. However, the SAR image provides an incomplete information (as roads of the observed scene leading thus to an ambiguous interpretation. In order to compensate the lack of features, the high spatial resolution panchromatic (P image is often used as a complementary data for improving the quality of the SAR image. The concept is based on the extraction of features (details from the P image in order to incorporate into the SAR image. Therefore, we propose an approach based on the use of the à trous wavelet decomposition (ATWD for extracting features from the P image. Experimental results show that the SAR-P composite image allows a better detection of lines, edges, and field boundaries.

  17. Application of Multifractal Analysis to Segmentation of Water Bodies in Optical and Synthetic Aperture Radar Satellite Images

    CERN Document Server

    Martin, Victor Manuel San

    2016-01-01

    A method for segmenting water bodies in optical and synthetic aperture radar (SAR) satellite images is proposed. It makes use of the textural features of the different regions in the image for segmentation. The method consists in a multiscale analysis of the images, which allows us to study the images regularity both, locally and globally. As results of the analysis, coarse multifractal spectra of studied images and a group of images that associates each position (pixel) with its corresponding value of local regularity (or singularity) spectrum are obtained. Thresholds are then applied to the multifractal spectra of the images for the classification. These thresholds are selected after studying the characteristics of the spectra under the assumption that water bodies have larger local regularity than other soil types. Classifications obtained by the multifractal method are compared quantitatively with those obtained by neural networks trained to classify the pixels of the images in covered against uncovered b...

  18. Automatic target classification of man-made objects in synthetic aperture radar images using Gabor wavelet and neural network

    Science.gov (United States)

    Vasuki, Perumal; Roomi, S. Mohamed Mansoor

    2013-01-01

    Processing of synthetic aperture radar (SAR) images has led to the development of automatic target classification approaches. These approaches help to classify individual and mass military ground vehicles. This work aims to develop an automatic target classification technique to classify military targets like truck/tank/armored car/cannon/bulldozer. The proposed method consists of three stages via preprocessing, feature extraction, and neural network (NN). The first stage removes speckle noise in a SAR image by the identified frost filter and enhances the image by histogram equalization. The second stage uses a Gabor wavelet to extract the image features. The third stage classifies the target by an NN classifier using image features. The proposed work performs better than its counterparts, like K-nearest neighbor (KNN). The proposed work performs better on databases like moving and stationary target acquisition and recognition against the earlier methods by KNN.

  19. Inversion of synthetic aperture radar interferograms for sourcesof production-related subsidence at the Dixie Valley geothermalfield

    Energy Technology Data Exchange (ETDEWEB)

    Foxall, B.; Vasco, D.W.

    2006-07-01

    We used synthetic aperture radar interferograms to imageground subsidence that occurred over the Dixie Valley geothermal fieldduring different time intervals between 1992 and 1997. Linear elasticinversion of the subsidence that occurred between April, 1996 and March,1997 revealed that the dominant sources of deformation during this timeperiod were large changes in fluid volumes at shallow depths within thevalley fill above the reservoir. The distributions of subsidence andsubsurface volume change support a model in which reduction in pressureand volume of hot water discharging into the valley fill from localizedupflow along the Stillwater range frontal fault is caused by drawdownwithin the upflow zone resulting from geothermal production. Our resultsalso suggest that an additional source of fluid volume reduction in theshallow valley fill might be similar drawdown within piedmont faultzones. Shallow groundwater flow in the vicinity of the field appears tobe controlled on the NW by a mapped fault and to the SW by a lineament ofas yet unknown origin.

  20. Ground settlement of Chek Lap Kok Airport, Hong Kong,detected by satellite synthetic aperture radar interferometry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Satellite synthetic aperture radar (SAR) interferometry is used to investigate the slowly accumulating ground settlement at the new Chek Lap Kok Airport in Hong Kong. Most of the land occupied by the airport was reclaimed from the sea and therefore certain ground settlement in the area has been expected. A pair of ERS-2 SAR images spanning nearly a year is used in the study. The high spatial resolution (20 m× 20 m) ground settlement map derived indicates that the settlement that occurred in the area over the time period is as large as 50 mm. The SAR measurement results agree with the levelling measurements at some benchmarks in the area to well within 1 cm(rms error),and the overall correlation between the two types of results is 0.89. The paper presents some brief background of interferometric SAR, and outlines the data processing methods and results.

  1. Reservoir monitoring and characterization using satellite geodetic data: Interferometric Synthetic Aperture Radar observations from the Krechba field, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio

    2008-05-01

    Deformation in the material overlying an active reservoir is used to monitor pressure change at depth. A sequence of pressure field estimates, eleven in all, allow us to construct a measure of diffusive travel time throughout the reservoir. The dense distribution of travel time values means that we can construct an exactly linear inverse problem for reservoir flow properties. Application to Interferometric Synthetic Aperture Radar (InSAR) data gathered over a CO{sub 2} injection in Algeria reveals pressure propagation along two northwest trending corridors. An inversion of the travel times indicates the existence of two northwest-trending high permeability zones. The high permeability features trend in the same direction as the regional fault and fracture zones. Model parameter resolution estimates indicate that the features are well resolved.

  2. A wave effect enabling universal frequency scaling, monostatic passive radar, incoherent aperture synthesis, and general immunity to jamming and interference

    CERN Document Server

    Guruprasad, V

    2008-01-01

    A fundamental Doppler-like but asymmetric wave effect that shifts received signals in frequency in proportion to their respective source distances, was recently described as means for a whole new generation of communication technology using angle and distance, potentially replacing TDM, FDM or CDMA, for multiplexing. It is equivalent to wave packet compression by scaling of time at the receiver, converting path-dependent phase into distance-dependent shifts, and can multiply the capacity of physical channels. The effect was hitherto unsuspected in physics, appears to be responsible for both the cosmological acceleration and the Pioneer 10/11 anomaly, and is exhibited in audio data. This paper discusses how it may be exploited for instant, passive ranging of signal sources, for verification, rescue and navigation; incoherent aperture synthesis for smaller, yet more accurate radars; universal immunity to jamming or interference; and precision frequency scaling of radiant energy in general.

  3. Orbital Synthetic Aperture Radar (SAR) for Mars Post Sample Return Exploration

    Science.gov (United States)

    Thompson, T. W.; Plaut, J. J.; Arvidson, R. E.; Paillou, P.

    2000-01-01

    A Mars orbital radar mission would use two frequencies to map the planet at 50 m resolution, penetrating 5-10 m. Some areas will be imaged at 5-m resolution. A 50-m resolution topographic map will be acquired, and surface changes detected.

  4. Performance Analysis of a High Resolution Airborne FM-CW Synthetic Aperture Radar

    NARCIS (Netherlands)

    Wit, J.J.M. de; Hoogeboom, P.

    2003-01-01

    Compact FM-CW technology combined with high resolution SAR techniques should pave the way for a small and cost effective imaging radar. A research project has been inìtiated to investigate the feasibility of FM-CW SAR. Within the framework of the project an operational airborne FM-CW SAR demonstrato

  5. Detection of oil spill and natural film in the marine environment by spaceborne Synthetic Aperture Radar

    International Nuclear Information System (INIS)

    The aim of this thesis is to improve the understanding of spaceborne SAR imaging of surface slicks, and subsequently to develop a method for classification of such slicks, including oil spill and natural chemical-biological film. Building up an extensive database of SAR imagery containing dark slicks, oil spills and its look-alikes have been studied and classified according to SAR image expression, backscatter, geographical occurrence and weather limitations. Natural film was identified as the look-alike most frequently difficult to distinguish from oil spills in the SAR imagery. During two experiments, major effort went into natural film sampling, documenting its composition, behaviour and SAR imaging characteristics. The results show that in general the concentration of fatty acids in natural films were an order of magnitude greater than outside the films. Coastal films had smaller fatty acid molecules, indicating marine sources, compared to the terrestrial sources of fjord films. The fjord films also gave a slightly higher damping in the SAR imagery than the coastal films. This was probably caused by differences in organic composition and concentration. A method was developed for using wind history in slick age estimation. Some trends in slick properties were discovered for oil films and natural films, but no one-to-one relationships were found. The supervised slick discrimination algorithm was developed and tested on 124 slicks in SAR imagery. Two look-alikes were classified as oil. They were both caused by other pollution spilled from oil platforms when wind history could not aid in age estimation. The expected problem with natural films being classified as oil was not reflected in the results, probably because the test data set does not include doubtful cases. 241 refs., 98 figs., 17 tabs

  6. Road-Aided Ground Slowly Moving Target 2D Motion Estimation for Single-Channel Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Zhirui Wang

    2016-03-01

    Full Text Available To detect and estimate ground slowly moving targets in airborne single-channel synthetic aperture radar (SAR, a road-aided ground moving target indication (GMTI algorithm is proposed in this paper. First, the road area is extracted from a focused SAR image based on radar vision. Second, after stationary clutter suppression in the range-Doppler domain, a moving target is detected and located in the image domain via the watershed method. The target’s position on the road as well as its radial velocity can be determined according to the target’s offset distance and traffic rules. Furthermore, the target’s azimuth velocity is estimated based on the road slope obtained via polynomial fitting. Compared with the traditional algorithms, the proposed method can effectively cope with slowly moving targets partly submerged in a stationary clutter spectrum. In addition, the proposed method can be easily extended to a multi-channel system to further improve the performance of clutter suppression and motion estimation. Finally, the results of numerical experiments are provided to demonstrate the effectiveness of the proposed algorithm.

  7. Road-Aided Ground Slowly Moving Target 2D Motion Estimation for Single-Channel Synthetic Aperture Radar.

    Science.gov (United States)

    Wang, Zhirui; Xu, Jia; Huang, Zuzhen; Zhang, Xudong; Xia, Xiang-Gen; Long, Teng; Bao, Qian

    2016-01-01

    To detect and estimate ground slowly moving targets in airborne single-channel synthetic aperture radar (SAR), a road-aided ground moving target indication (GMTI) algorithm is proposed in this paper. First, the road area is extracted from a focused SAR image based on radar vision. Second, after stationary clutter suppression in the range-Doppler domain, a moving target is detected and located in the image domain via the watershed method. The target's position on the road as well as its radial velocity can be determined according to the target's offset distance and traffic rules. Furthermore, the target's azimuth velocity is estimated based on the road slope obtained via polynomial fitting. Compared with the traditional algorithms, the proposed method can effectively cope with slowly moving targets partly submerged in a stationary clutter spectrum. In addition, the proposed method can be easily extended to a multi-channel system to further improve the performance of clutter suppression and motion estimation. Finally, the results of numerical experiments are provided to demonstrate the effectiveness of the proposed algorithm. PMID:26999140

  8. Numerical simulation and validation of ocean waves measured by an Along-Track Interferometric Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; HE Yijun; Paris W.VACHON

    2008-01-01

    A new nonlinear integral transform of ocean wave spectra into Along-Track Interferometric Synthetic Aperture Radar (ATI-SAR )image spectra is described.ATI-SAR phase image spectra are calculated for various sea states and radar configurations based on the nonlinear integral transform.The numerical simulations show that the slant range to velocity ratio(R/V),significant wave height to ocean wavelength ratio(Hs/λ),the baseline (2B) and incident angle(θ)affect ATI-SAR imaging.The ATI-SAR imaging theory is validated by means of Two X-band,HH-polarized ATI-SAR phase images of ocean waves and eight C-band,HH-polarized ATI-SAR phase image spectra of ocean waves.It is shown that ATI-SAR phase image spectra are in agreement with those calculated by forward mapping in situ directional wave soectra collected simultaneously with available ATI-SAR observations.ATI-SAR spectral correlation coefficients between observed and simulated are greater than 0.6 and ale not sensitive to the degree of nonlinearity.However,the ATI-SAR phase image spectral turns towards the range direction.even if the real ocean wave direction is 30°.It is also shown that the ATI-SAR imaging mechanism is significantly affected by the degree of velocity bunching nonlinearity,especially for high values of R/V and Hs/λ.

  9. Estimation of surface roughness in a semiarid region from C-band ERS-1 synthetic aperture radar data

    Directory of Open Access Journals (Sweden)

    E. E. Sano

    1999-12-01

    Full Text Available In this study, we investigated the feasibility of using the C-band European Remote Sensing Satellite (ERS-1 synthetic aperture radar (SAR data to estimate surface soil roughness in a semiarid rangeland. Radar backscattering coefficients were extracted from a dry and a wet season SAR image and were compared with 47 in situ soil roughness measurements obtained in the rocky soils of the Walnut Gulch Experimental Watershed, southeastern Arizona, USA. Both the dry and the wet season SAR data showed exponential relationships with root mean square (RMS height measurements. The dry C-band ERS-1 SAR data were strongly correlated (R² = 0.80, while the wet season SAR data have somewhat higher secondary variation (R² = 0.59. This lower correlation was probably provoked by the stronger influence of soil moisture, which may not be negligible in the wet season SAR data. We concluded that the single configuration C-band SAR data is useful to estimate surface roughness of rocky soils in a semiarid rangeland.

  10. Millimeter wave and synthetic aperture radar; Proceedings of the Meeting, Orlando, FL, Mar. 27, 28, 1989

    Science.gov (United States)

    Huddleston, G. K.; Tanenhaus, Martin; Williams, Brian P.

    The present conference on mm-wave and SAR architectures and algorithms for both signal processing/calibration and image processing/exploitation discusses the use of the chirp z-transform for radar image formation, digital interpolations for polar-format processing, polarimetric calibrations using distributed clutter, imaging in multidimensions and monopulse processing and practice, vector quantization for SAR data-rate reduction, and digital filter design for radar image formation. Also discussed are a shadow-tracking algorithm for moving-target detection, Doppler-rate filtering for the detection of moving targets with SAR, mm-wave planar integrated waveguide transceivers, an advanced microwave precipitation radiometer, and a Kelvin-wake image artifact for SAR.

  11. Measurement of turbulence in the oceanic mixed layer using Synthetic Aperture Radar (SAR)

    OpenAIRE

    George, S.G.; Tatnall, A. R. L.

    2012-01-01

    Turbulence in the surface layer of the ocean contributes to the transfer of heat, gas and momentum across the air-sea boundary. As such, study of turbulence in the ocean surface layer is becoming increasingly important for understanding its effects on climate change. Direct Numerical Simulation (DNS) techniques were implemented to examine the interaction of small-scale wake turbulence in the upper ocean layer with incident electromagnetic radar waves. Hydrodynamic-electromag...

  12. A Review on Compressive Sensing in Synthetic Aperture Radar (SAR)

    OpenAIRE

    Ankit; Manoj Ahlawat

    2014-01-01

    The system parameters have been specified in view of all the constraints and practical limitations. The performance metrics of the system such as range resolution and cross-range resolution, etc. have been worked out and the system level specification has been worked out keeping in view the desired performance. Using MATLAB as major tool, the specified system parameters have been tested for their accuracy and correctness. A simulation of Pulse Doppler radar is completed which includes wavefor...

  13. Mobile Mapping by Fmcw Synthetic Aperture Radar Operating at 300 GHZ

    Science.gov (United States)

    Palm, S.; Sommer, R.; Hommes, A.; Pohl, N.; Stilla, U.

    2016-06-01

    While optical cameras or laser systems are widely used for mobile mapping low attention was payed for radar systems. Due to new semiconductor technologies, compact and leight weight SAR systems based on the Frequency Modulated Continuous Wave (FMCW) principle in the millimeter wave domain can serve for mobile radar mapping on cars. For mapping of long stripes along roads in close range a special strategy for focusing of SAR images was developed. Hereby local adapted planes for processing are used considering the IMU data of the sensor. An experimental system was designed for high resolution radar mapping of urban scenes in close range geometry. This small and leight weighted system has a bandwidth of 30 GHz (5 mm resolution) and operates with 300 GHz in the lower terahertz domain. Experiments with a van in an urban scenario were carried out for proof of applicability of an operating SAR system resolving objects in the subcentimeter domain. The results show that narrow cracks in the asphalt of the road are visible and the measuring of small metallic objects placed in the scene is possible. Based on this mobile mapping techniques a first result from an acquisition of vertical facade structure is shown.

  14. Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia.

    Science.gov (United States)

    Krohn, M.D.; Milton, N.M.; Segal, D.B.

    1983-01-01

    Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.-from Authors

  15. Detection and classification of oil spills in MODIS satellite imagery

    OpenAIRE

    Alawadi, Fahad A.M.

    2011-01-01

    Using satellite imagery to achieve an early and accurate identification of oil spills will contribute towards the reduction of their impact on the marine ecosystem. Satellite imagery provided by the synthetic aperture radar (SAR) sensors are widely used for this task over the multi-temporal and multi-band visible near infra-red (VNIR) sensors. This is due to the SAR imaging capabilities through clouds, dust storms, soot and at night times, which limit the capability of VNIR sensors. However, ...

  16. Digital Elevation Models of Greenland based on combined radar and laser altimetry as well as high-resolution stereoscopic imagery

    Science.gov (United States)

    Levinsen, J. F.; Smith, B. E.; Sandberg Sorensen, L.; Khvorostovsky, K.; Simonsen, S. B.; Forsberg, R.

    2015-12-01

    A number of Digital Elevation Models (DEMs) of Greenland exist, each of which are applicable for different purposes. This study presents two such DEMs: One developed by merging contemporary radar and laser altimeter data, and one derived from high-resolution stereoscopic imagery. All products are made freely available. The former DEM covers the entire Greenland. It is specific to the year 2010, providing it with an advantage over previous models suffering from either a reduced spatial/ temporal data coverage or errors from surface elevation changes (SEC) occurring during data acquisition. Radar data are acquired with Envisat and CryoSat-2, and laser data with the Ice, Cloud, and land Elevation Satellite, the Land, Vegetation, and Ice Sensor, and the Airborne Topographic Mapper. Correcting radar data for errors from slope effects and surface penetration of the echoes, and merging these with laser data, yields a DEM capable of resolving both surface depressions as well as topographic features at higher altitudes. The spatial resolution is 2 x 2 km, making the DEM ideal for application in surface mass balance studies, SEC detection from radar altimetry, or for correcting such data for slope-induced errors. The other DEM is developed in a pilot study building the expertise to map all ice-free parts of Greenland. The work combines WorldView-2 and -3 as well as GeoEye1 imagery from 2014 and 2015 over the Disko, Narsaq, Tassilaq, and Zackenberg regions. The novelty of the work is the determination of the product specifications after elaborate discussions with interested parties from government institutions, the tourist industry, etc. Thus, a 10 m DEM, 1.5 m orthophotos, and vector maps are produced. This opens to the possibility of using orthophotos with up-to-date contour lines or for deriving updated coastlines to aid, e.g., emergency management. This allows for a product development directly in line with the needs of parties with specific interests in Greenland.

  17. Detecting Faults in Southern California using Computer-Vision Techniques and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) Interferometry

    Science.gov (United States)

    Barba, M.; Rains, C.; von Dassow, W.; Parker, J. W.; Glasscoe, M. T.

    2013-12-01

    Knowing the location and behavior of active faults is essential for earthquake hazard assessment and disaster response. In Interferometric Synthetic Aperture Radar (InSAR) images, faults are revealed as linear discontinuities. Currently, interferograms are manually inspected to locate faults. During the summer of 2013, the NASA-JPL DEVELOP California Disasters team contributed to the development of a method to expedite fault detection in California using remote-sensing technology. The team utilized InSAR images created from polarimetric L-band data from NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) project. A computer-vision technique known as 'edge-detection' was used to automate the fault-identification process. We tested and refined an edge-detection algorithm under development through NASA's Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response (E-DECIDER) project. To optimize the algorithm we used both UAVSAR interferograms and synthetic interferograms generated through Disloc, a web-based modeling program available through NASA's QuakeSim project. The edge-detection algorithm detected seismic, aseismic, and co-seismic slip along faults that were identified and compared with databases of known fault systems. Our optimization process was the first step toward integration of the edge-detection code into E-DECIDER to provide decision support for earthquake preparation and disaster management. E-DECIDER partners that will use the edge-detection code include the California Earthquake Clearinghouse and the US Department of Homeland Security through delivery of products using the Unified Incident Command and Decision Support (UICDS) service. Through these partnerships, researchers, earthquake disaster response teams, and policy-makers will be able to use this new methodology to examine the details of ground and fault motions for moderate to large earthquakes. Following an earthquake, the newly discovered faults can

  18. Microlocal analysis of synthetic aperture radar imaging in the presence of a vertical wall

    International Nuclear Information System (INIS)

    We consider the problem of imaging a target located nearby a perfectly reflective vertical wall by making use of a SAR system in the case where a single pass is made over the scene of which we expect to be able to reconstruct a two-dimensional image. Many of the conventional methods make the assumption that the wave has scattered just once from the region to be imaged before returning to the sensor to be recorded. The purpose of this paper is to give a brief idea about how this restriction can be partially removed from a microlocal analysis point of view, in the case where the radar is operating with a poor directivity. The simple case where the antenna is flying perpendicularly to the wall is presented here, while a more in-depth study of this method will be analyzed elsewhere

  19. Optimization of Soil Hydraulic Model Parameters Using Synthetic Aperture Radar Data: An Integrated Multidisciplinary Approach

    DEFF Research Database (Denmark)

    Pauwels, Valentijn; Balenzano, Anna; Satalino, Giuseppe;

    2009-01-01

    been focused on the retrieval of land and biogeophysical parameters (e.g., soil moisture contents). One relatively unexplored issue consists of the optimization of soil hydraulic model parameters, such its, for example, hydraulic conductivity, values, through remote sensing. This is due to the fact...... that no direct relationships between the remote-sensing observations, more specifically radar backscatter values, and the parameter values can be derived. However, land surface models can provide these relationships. The objective of this paper is to retrieve a number of soil physical model parameters through...... model is, thus, used to determine the relationship between the soil physical parameters and the remote-sensing data. An analysis is then performed, relating the retrieved soil parameters to the soil texture data available over the study area. The results of the study show that there is a potential...

  20. S-band synthetic aperture radar on-board NISAR satellite

    Science.gov (United States)

    Misra, Tapan; Bhan, Rakesh; Putrevu, Deepak; Mehrotra, Priyanka; Chakrabarty, Soumyabrata

    2016-05-01

    provide single, dual, compact and quasi-quad polarization imaging modes. Centre frequency for S-band SAR is 3200MHz with highest bandwidth of 75MHz. S-Band SAR utilizes 24 transmit receive modules (T/R Modules) to illuminate >240kms swath during transmit event and digital beam forming (DBF) on receive to reduce data rate by combining 24 receive channels and enhance SNR of the system. This paper provides details of S-band SAR system design, configuration and realization which is a challenging task since both L-band and S-band radars need to operate at same PRF and clock reference during simultaneous imaging operation. Further to this, SweepSAR technique demands PRF dithering (changing) to avoid dead gaps in the swath due to receive echo conflicting with transmit event.

  1. The effect of wave breaking on surface wave imaging by Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of ocean wave breaking as a non-Bragg mechanism on backscattering cross-section and modulation transfer functions (MTF) of radar was investigated based on Bragg resonance theory and parametric method. The result showed that the additional effect of wave breaking on backscattering cross-section is not more than 20% except for the small incident angle of VV polarized electromagnetic (e.m.) wave but is significant for HH polarized e.m. wave. Breaking waves lead to increase in the modulus of tilt modulation MTF and the larger the wind speed, the faster the increase. For large incident angle, the modulus of tilt modulation MTF with wave breaking decreases quickly with incident angle for HH polarization and approach to that without wave breaking for VV polarization. The hydrodynamic MTF increases 30%-60% when considering wave breaking and the increase is larger for HH polarization than for VV polarization.

  2. Detecting land subsidence near metro lines in the Baoshan district of Shanghai with multi-temporal interferometric synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    Tao Li; Guoxiang Liu; Hui Lin; Rui Zhang; Hongguo Jia; Bing Yu

    2014-01-01

    Land subsidence is a major factor that affects metro line (ML) stability. In this study, an improved multi-temporal interferometric synthetic aperture radar (InSAR) (MTI) method to detect land subsidence near MLs is pre-sented. In particular, our multi-temporal InSAR method provides surface subsidence measurements with high observation density. The MTI method tracks both point-like targets and distributed targets with temporal radar back-scattering steadiness. First, subsidence rates at the point targets with low-amplitude dispersion index (ADI) values are extracted by applying a least-squared estimator on an optimized freely connected network. Second, to reduce error propagation, the pixels with high-ADI values are classified into several groups according to ADI intervals and processed using a Pearson correlation coefficient and hierarchical analysis strategy to obtain the distributed targets. Then, nonlinear subsidence components at all point-like and dis-tributed targets are estimated using phase unwrapping and spatiotemporal filtering on the phase residuals. The proposed MTI method was applied to detect land subsidence near MLs of No. 1 and 3 in the Baoshan district of Shanghai using 18 TerraSAR-X images acquired between April 21, 2008 and October 30, 2010. The results show that the mean subsidence rates of the stations distributed along the two MLs are -12.9 and -14.0 mm/year. Furthermore, three subsidence funnels near the MLs are discovered through the hierarchical analysis. The testing results demonstrate the satisfactory capacity of the proposed MTI method in pro-viding detailed subsidence information near MLs.

  3. Mapping Wetlands of the North American Boreal Zone from Satellite Radar Imagery

    Science.gov (United States)

    Moghaddam, M.; McDonald, K.; Podest, E.

    2003-12-01

    The accurate assessment of spatial and temporal distributions of wetlands can have a large impact in improving the estimates of the global net carbon exchange. Synthetic aperture radar (SAR) sensors are well suited to monitoring wetlands because of their ability to detect various combinations of standing water and vegetation conditions. They also penetrate cloud cover and do not require solar illumination, allowing the collection of frequent seasonal data. The recent availability of large-scale satellite SAR mosaics is making it possible to generate baseline wetlands map of the north American boreal zone, where it is hypothesized to exist a substantial carbon sink, and 15-20 percent of the land surface is comprised of wetlands. The present work utilizes the summer and winter JERS-1 mosaics of the region as well as several large-scale coverages of ERS-2 for mapping the north America boreal wetlands. As an intermediate product, an open water map of the area is also being generated, derived from 100-meter resolution JERS-1 SAR mosaic products. We present a large-scale wetlands map covering large parts of Alaska and Canada, generated using a classification algorithm applied to coregistered JERS-1 (L-band HH polarizations) and ERS-2 (C-band VV polarization) SAR mosaics. The former exists for almost the entire area of Alaska and Canada, whereas currently we have access to the latter only for Alaska and Western Canada. The classification method is based on a rule-based decision-tree algorithm, and divides the landscape into the following classes: open water (possibly with sparse emergent vegetation), flooded woody vegetation (e.g., forests), flooded herbaceous vegetation, nonflooded woody vegetation, nonflooded herbaceous vegetation, and nonflooded-nonvegetated. The five standard Canadian wetlands classes of fens, bogs, swamps, marshes, and open water can be mapped into one or more of our vegetation-based wetlands classes. Several local-scale products have been validated

  4. Venus Radar Mapper (VRM): Multimode radar system design

    Science.gov (United States)

    Johnson, William T. K.; Edgerton, Alvin T.

    1986-01-01

    The surface of Venus has remained a relative mystery because of the very dense atmosphere that is opaque to visible radiation and, thus, normal photographic techniques used to explore the other terrestrial objects in the solar system are useless. The atmosphere is, however, almost transparent to radar waves and images of the surface have been produced via Earth-based and orbital radars. The technique of obtaining radar images of a surface is variously called side looking radar, imaging radar, or synthetic aperture radar (SAR). The radar requires a moving platform in which the antenna is side looking. High resolution is obtained in the cross-track or range direction by conventional radar pulse encoding. In the along-track or azimuth direction, the resolution would normally be the antenna beam width, but for the SAR case, a much longer antenna (or much sharper beam) is obtained by moving past a surface target as shown, and then combining the echoes from many pulses, by using the Doppler data, to obtain the images. The radar design of the Venus Radar Mapper (VRM) is discussed. It will acquire global radar imagery and altimetry data of the surface of Venus.

  5. Synthesis of Generalized Vertical-Plane Weather Radar Imagery Along Aircraft Flight Paths

    OpenAIRE

    Mahapatra, Pravas R; Makkapati, Vishnu V

    2005-01-01

    A method for synthesizing weather pictures in vertical planes along aircraft flight paths is presented. The weather data are derived from a number of Doppler radars covering different parts of the flight path. The flight path consists of straight segments with arbitrary offset and orientation with respect to individual radar locations. The intersection of radar scanning cones with the vertical plane segments are described as families of radial lines or hyperbolas depending on whether the flig...

  6. Estimating Evapotranspiration over Heterogeneously Vegetated Surfaces using Large Aperture Scintillometer, LiDAR, and Airborne Multispectral Imagery

    Science.gov (United States)

    Geli, H. M.; Neale, C. M.; Pack, R. T.; Watts, D. R.; Osterberg, J.

    2011-12-01

    Estimates of evapotranspiration (ET) over heterogeneous areas is challenging especially in water-limited sparsely vegetated environments. New techniques such as airborne full-waveform LiDAR (Light Detection and Ranging) and high resolution multispectral and thermal imagery can provide enough detail of sparse canopies to improve energy balance model estimations as well as footprint analysis of scintillometer data. The objectives of this study were to estimate ET over such areas and develop methodologies for the use of these airborne data technologies. Because of the associated heterogeneity, this study was conducted over the Cibola National wildlife refuge, southern California on an area dominated with tamarisk (salt cedar) forest (90%) interspersed with arrowweed and bare soil (10%). A set of two large aperture scintillometers (LASs) were deployed over the area to provide estimates of sensible heat flux (HLAS). The LASs were distributed over the area in a way that allowed capturing different surface spatial heterogeneity. Bowen ratio systems were used to provide hydrometeorological variables and surface energy balance fluxes (SEBF) (i.e. Rn, G, H, and LE) measurements. Scintillometer-based estimates of HLAS were improved by considering the effect of the corresponding 3D footprint and the associated displacement height (d) and the roughness length (z0) following Geli et al. (2011). The LiDAR data were acquired using the LASSI Lidar developed at Utah State University (USU). The data was used to obtain 1-m spatial resolution DEM's and vegetation canopy height to improve the HLAS estimates. The BR measurements of Rn and G were combined with LAS estimates, HLAS, to provide estimates of LELASas a residual of the energy balance equation. A thermal remote sensing model namely the two source energy balance (TSEB) of Norman et al. (1995) was applied to provide spatial estimates of SEBF. Four airborne images at 1-4 meter spatial resolution acquired using the USU airborne

  7. 合成孔径雷达小型卫星进展%Progress of Small Satellite of Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    姜秀鹏; 常新亚; 姚芳; 李黎

    2016-01-01

    随着星载合成孔径雷达( SAR)技术的发展,合成孔径雷达卫星的小型化将成为未来的一个研究热点。为探讨合成孔径雷达小型卫星的进展及发展趋势,文章调研了国外合成孔径雷达卫星发展现状,结合适用于小卫星的合成孔径雷达载荷的天线体制,提炼总结出未来合成孔径雷达小型卫星以高分辨率与宽覆盖、多极化与多模式、编队与组网运行、星上实时处理、SAR与光学载荷共存、SAR与数传一体化设计等技术为特征的发展趋势,可以为合成孔径雷达小型卫星的设计提供方向性参考。%With the development of synthetic aperture radar( SAR) ,miniaturization of synthetic aperture radar satellite will be a hot issue in research To investigate the progress and development trend of the small satellite of synthetic aperture radar,this paper researched the current situation of foreign synthetic aperture radar satellites,and combined the antenna sys-tem which suits for small sateiies,abstracted and summarized the development trend of the future small satellites of syntietic apreture radar which should have the technical features of high resolution and wide swath, multi-polarization and multimode, operation in formation and constellation,on-board real-time processing,coexistence of SAR and optical payload,integration design of SAR and data transmission,etc. This paper can provide a kind of directional reference for the design of small satel-lite of synthetic aperture radar.

  8. Coastal flood inundation monitoring with Satellite C-band and L-band Synthetic Aperture Radar data

    Science.gov (United States)

    Ramsey, Elijah W., III; Rangoonwala, Amina; Bannister, Terri

    2013-01-01

    Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245).

  9. Analysis of ERS 1 synthetic aperture radar data of frozen lakes in northern Montana and implications for climate studies

    Science.gov (United States)

    Hall, Dorothy K.; Fagre, Daniel B.; Klasner, Fritz; Linebaugh, Gregg; Liston, Glen E.

    1994-01-01

    Lakes that freeze each winter are good indicators of regional climate change if key parameters, such as freeze-up and breakup date and maximum ice thickness, are measured over a decade-scale time frame. Synthetic aperture radar (SAR) satellite data have proven to be especially useful for measurement of climatologically significant parameters characteristic of frozen lakes. In this paper, five lakes in Glacier National Park, Montana, have been studied both in the field and using Earth Remote-Sensing Satellite (ERS) 1 SAR data during the 1992-1993 winter. The lakes are characterized by clear ice, sometimes with tubular or rounded bubbles, and often with a layer of snow ice on top of the clear ice. They are also often snow covered. Freeze-up is detected quite easily using ERS 1 SAR data as soon as a thin layer of ice forms. The effect of snow ice on the backscatter is thought to be significant but is, as yet, undetermined. On the five lakes studied, relative backscatter was found to increase with ice thickness until a maximum was reached in February. Breakup, an often ill-defined occurrence, is difficult to detect because surface water causes the SAR signal to be absorbed, thus masking the ice below. Comparison of the bubble structure of thaw lakes in northern Alaska with lakes in northern Montana has shown that the ice structure is quite different, and this difference may contribute to differential SAR signature evolution in the lakes of the two areas.

  10. Riding Quality Model for Asphalt Pavement Monitoring Using Phase Array Type L-band Synthetic Aperture Radar (PALSAR

    Directory of Open Access Journals (Sweden)

    Kamiya Yoshikazu

    2010-11-01

    Full Text Available There are difficulties associated with near-real time or frequent pavement monitoring, because it is time consuming and costly. This study aimed to develop a binary logit model for the evaluation of highway riding quality, which could be used to monitor pavement conditions. The model was applied to investigate the influence of backscattering values of Phase Array type L-band Synthetic Aperture Radar (PALSAR. Training data obtained during 3–7 May 2007 was used in the development process, together with actual international roughness index (IRI values collected along a highway in Ayutthaya province, Thailand. The analysis showed that an increase in the backscattering value in the HH or the VV polarization indicated the poor condition of the pavement surface and, of the two, the HH polarization is more suitable for developing riding quality evaluation. The model developed was applied to analyze highway number 3467, to demonstrate its capability. It was found that the assessment accuracy of the prediction of the highway level of service was 97.00%. This is a preliminary study of the proposed technique and more intensive investigation must be carried out using ALOS/PALSAR images in various seasons.

  11. Integration of speckle de-noising and image segmentation using Synthetic Aperture Radar image for flood extent extraction

    Indian Academy of Sciences (India)

    J Senthilnath; H Vikram Shenoy; Ritwik Rajendra; S N Omkar; V Mani; P G Diwakar

    2013-06-01

    Flood is one of the detrimental hydro-meteorological threats to mankind. This compels very efficient flood assessment models. In this paper, we propose remote sensing based flood assessment using Synthetic Aperture Radar (SAR) image because of its imperviousness to unfavourable weather conditions. However, they suffer from the speckle noise. Hence, the processing of SAR image is applied in two stages: speckle removal filters and image segmentation methods for flood mapping. The speckle noise has been reduced with the help of Lee, Frost and Gamma MAP filters. A performance comparison of these speckle removal filters is presented. From the results obtained, we deduce that the Gamma MAP is reliable. The selected Gamma MAP filtered image is segmented using Gray Level Co-occurrence Matrix (GLCM) and Mean Shift Segmentation (MSS). The GLCM is a texture analysis method that separates the image pixels into water and non-water groups based on their spectral feature whereas MSS is a gradient ascent method, here segmentation is carried out using spectral and spatial information. As test case, Kosi river flood is considered in our study. From the segmentation result of both these methods are comprehensively analysed and concluded that the MSS is efficient for flood mapping.

  12. Focusing vibrating targets in frequency-modulation continuous-wave-synthetic aperture radar with Doppler keystone transform

    Science.gov (United States)

    Hu, Yuxin; Zhang, Yuan; Sun, Jinping; Lei, Peng

    2016-04-01

    Vibrating targets generally induce sinusoidal micro-Doppler modulation in high resolution synthetic aperture radar (SAR). They could cause defocused and ghost results by conventional imaging algorithms. This paper proposes a method on vibrating target imaging in frequency-modulation continuous-wave (FMCW) SAR systems. The continuous motion of sensor platform during pulse time is considered in the signal model. Based on Bessel series expansion of the signal in the azimuth direction, the influence of platform motion on the azimuth frequency is eliminated after dechirp and deskew. In addition, the range walk is compensated in the two-dimensional frequency domain by Doppler keystone transform. Next, using range cell migration correction, the azimuth quadratic phase compensation and the range curvature correction are made in range-Doppler domain for the focus of paired echoes. The residual video phase of paired echoes is eliminated, and vibration parameters are estimated to compensate in the sinusoidal modulation phase. Then the deghosted image of vibrating targets can be obtained. The proposed method is applicable to multiple targets with various vibrating states due to no need of a priori knowledge of targets. Finally, simulations are carried out to validate the effectiveness of the method in FMCW-SAR imaging of vibrating targets.

  13. Millimeter-wave Ground-based Synthetic Aperture Radar Imaging for Foreign Object Debris Detection: Experimental Studies at Short Ranges

    Science.gov (United States)

    Yigit, Enes; Demirci, Sevket; Unal, Atilla; Ozdemir, Caner; Vertiy, Alexey

    2012-12-01

    In this paper, millimeter-wave imaging of foreign object debris (FOD)-type objects on the ground is studied with the help of ground-based synthetic aperture radar (GB-SAR) technique. To test the feasibility of detecting runway FODs with this technique, some preliminary experiments are conducted within short antenna-to-target ranges of small imaging patches. An automated stripmap GB-SAR system with stepped-frequency transmission is constructed together with a quasi-monostatic data collection operation. The imaging experiments for various braces and screws are then carried out by using 32- 36 GHz and 90- 95 GHz frequency bands of the millimeter-wave. Images reconstructed by a matched-filter based algorithm are analyzed to determine the proper system parameters for an efficient imaging and to comprehend the factors against a successful detection. Results demonstrate the capability of GB-SAR imaging in accurately locating these FOD-like targets under near-range operating conditions.

  14. Synthetic Aperture Radar (SAR Interferometry for Assessing Wenchuan Earthquake (2008 Deforestation in the Sichuan Giant Panda Site

    Directory of Open Access Journals (Sweden)

    Fulong Chen

    2014-07-01

    Full Text Available Synthetic aperture radar (SAR has been an unparalleled tool in cloudy and rainy regions as it allows observations throughout the year because of its all-weather, all-day operation capability. In this paper, the influence of Wenchuan Earthquake on the Sichuan Giant Panda habitats was evaluated for the first time using SAR interferometry and combining data from C-band Envisat ASAR and L-band ALOS PALSAR data. Coherence analysis based on the zero-point shifting indicated that the deforestation process was significant, particularly in habitats along the Min River approaching the epicenter after the natural disaster, and as interpreted by the vegetation deterioration from landslides, avalanches and debris flows. Experiments demonstrated that C-band Envisat ASAR data were sensitive to vegetation, resulting in an underestimation of deforestation; in contrast, L-band PALSAR data were capable of evaluating the deforestation process owing to a better penetration and the significant coherence gain on damaged forest areas. The percentage of damaged forest estimated by PALSAR decreased from 20.66% to 17.34% during 2009–2010, implying an approximate 3% recovery rate of forests in the earthquake impacted areas. This study proves that long-wavelength SAR interferometry is promising for rapid assessment of disaster-induced deforestation, particularly in regions where the optical acquisition is constrained.

  15. Comparative analysis for detecting areas with building damage from several destructive earthquakes using satellite synthetic aperture radar images

    Science.gov (United States)

    Matsuoka, Masashi; Yamazaki, Fumio

    2010-11-01

    Earthquakes that have caused large-scale damage in developed areas, such as the 1994 Northridge and 1995 Kobe events, remind us of the importance of making quick damage assessments in order to facilitate the resumption of normal activities and restoration planning. Synthetic aperture radar (SAR) can be used to record physical aspects of the Earth's surface under any weather conditions, making it a powerful tool in the development of an applicable method for assessing damage following natural disasters. Detailed building damage data recorded on the ground following the 1995 Kobe earthquake may provide an invaluable opportunity to investigate the relationship between the backscattering properties and the degree of damage. This paper aims to investigate the differences between the backscattering coefficients and the correlations derived from pre- and post-earthquake SAR intensity images to smoothly detect areas with building damage. This method was then applied to SAR images recorded over the areas affected by the 1999 Kocaeli earthquake in Turkey, the 2001 Gujarat earthquake in India, and the 2003 Boumerdes earthquake in Algeria. The accuracy of the proposed method was examined and confirmed by comparing the results of the SAR analyses with the field survey data.

  16. FrFT-CSWSF: Estimating cross-range velocities of ground moving targets using multistatic synthetic aperture radar

    Directory of Open Access Journals (Sweden)

    Li Chenlei

    2014-10-01

    Full Text Available Estimating cross-range velocity is a challenging task for space-borne synthetic aperture radar (SAR, which is important for ground moving target indication (GMTI. Because the velocity of a target is very small compared with that of the satellite, it is difficult to correctly estimate it using a conventional monostatic platform algorithm. To overcome this problem, a novel method employing multistatic SAR is presented in this letter. The proposed hybrid method, which is based on an extended space-time model (ESTIM of the azimuth signal, has two steps: first, a set of finite impulse response (FIR filter banks based on a fractional Fourier transform (FrFT is used to separate multiple targets within a range gate; second, a cross-correlation spectrum weighted subspace fitting (CSWSF algorithm is applied to each of the separated signals in order to estimate their respective parameters. As verified through computer simulation with the constellations of Cartwheel, Pendulum and Helix, this proposed time-frequency-subspace method effectively improves the estimation precision of the cross-range velocities of multiple targets.

  17. FrFT-CSWSF:Estimating cross-range velocities of ground moving targets using multistatic synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    Li Chenlei; Liu Mei; Zhao Bowen; Zhang Lei

    2014-01-01

    Estimating cross-range velocity is a challenging task for space-borne synthetic aperture radar (SAR), which is important for ground moving target indication (GMTI). Because the velocity of a target is very small compared with that of the satellite, it is difficult to correctly estimate it using a conventional monostatic platform algorithm. To overcome this problem, a novel method employ-ing multistatic SAR is presented in this letter. The proposed hybrid method, which is based on an extended space-time model (ESTIM) of the azimuth signal, has two steps: first, a set of finite impulse response (FIR) filter banks based on a fractional Fourier transform (FrFT) is used to sep-arate multiple targets within a range gate;second, a cross-correlation spectrum weighted subspace fitting (CSWSF) algorithm is applied to each of the separated signals in order to estimate their respective parameters. As verified through computer simulation with the constellations of Cart-wheel, Pendulum and Helix, this proposed time-frequency-subspace method effectively improves the estimation precision of the cross-range velocities of multiple targets.

  18. Heterogeneous Fault Mechanisms of the 6 October 2008 MW 6.3 Dangxiong (Tibet) Earthquake Using Interferometric Synthetic Aperture Radar Observations

    OpenAIRE

    Caijun Xu; Bei Xu; Yangmao Wen; Yang Liu

    2016-01-01

    Most current crustal deformation models do not account for topographic effects, crustal lateral variations, and complex fault geometries. To overcome these limitations, we apply finite element models constrained by interferometric Synthetic Aperture Radar (InSAR) images of co-seismic displacements to the 2008 Mw 6.3 Dangxiong earthquake that occurred in Yadong–Gulu rift, southern Tibet. For mountainous plateau environments, InSAR observations are advantageous for studying crustal deformation ...

  19. Automatic near real-time flood detection in high resolution X-band synthetic aperture radar satellite data using context-based classification on irregular graphs

    OpenAIRE

    Martinis, Sandro

    2010-01-01

    This thesis is an outcome of the project “Flood and damage assessment using very high resolution SAR data” (SAR-HQ), which is embedded in the interdisciplinary oriented RIMAX (Risk Management of Extreme Flood Events) programme, funded by the Federal Ministry of Education and Research (BMBF). It comprises the results of three scientific papers on automatic near real-time flood detection in high resolution X-band synthetic aperture radar (SAR) satellite data for operational rapid mapping activi...

  20. Mapping Wetlands of Alaska and Western Canada from Satellite Radar Imagery

    Science.gov (United States)

    Moghaddam, M.; McDonald, K. C.; Cihlar, J.; Chen, W.

    2002-12-01

    Boreal wetlands have an important function in processing methane, carbon dioxide, nitrogen, and sulfur as well as in sequestering carbon. The type and extent of high latitude wetlands are important indicators of methane source areas, while upland forests in the taiga are important methane-consuming sinks. Wetlands regulate biogeochemical processes such as methane production, and fix and store organic matter in the long run. The extent and complexity of wetland ecosystems are still quite uncertain partly because it is difficult to discriminate wetlands on a global scale using widely available optical remote sensing data and techniques, which are not able to detect standing water conditions under most vegetation. The accurate assessment of areal and temporal distributions of wetlands can have a large impact in improving the estimates of the global net carbon exchange. Synthetic Aperture Radar (SAR) sensors are well suited to monitoring wetlands because of their ability to detect various combinations of standing water and vegetation structure and moisture conditions. SARs also penetrate cloud cover and do not require solar illumination, allowing the collection of frequent seasonal data. Multifrequency, multipolarization SAR data needed to classify various wetlands types have been available for several years from airborne systems. Although existing spaceborne SAR data are limited to single frequency and single polarization configurations, combining data from different SAR satellites can emulate a space-based multifrequency multipolarization capability. No large-scale wetlands mapping efforts have been carried out thus far due unavailability of appropriate SAR data sets. However, with the recent availability of the JERS-1 north American boreal mosaic augmented by the partial ERS-2 overlapping data, it is now possible to generate maps of wetland extent, as well as set the stage for performing time-series analysis with future planned SAR satellite systems. We present a

  1. Coastal Monitoring Using L-band Synthetic Aperture Radar (SAR) Image Data - Some Case Studies in Asian Delta Areas

    Science.gov (United States)

    Tanaka, A.

    2014-12-01

    Coastal geomorphology is highly variable as it is affected by sea-level changes and other naturally- and human-induced fluctuations. To effectively assess and monitor geomorphological changes in various time scales is thus critical for coastal management. Asian mega deltas are vulnerable to a sea-level rise due to its low-lying delta plain, and are dynamic region given a large amount of sediment supply. However, limited data availability and accessibility in the deltas have prevented establishment of systematic coastal monitoring. A variety of remote sensing systems can be used to monitor geomorphological changes in coastal areas as it has wide spatial coverage and high temporal repeatability. Especially, analysis using SAR (Synthetic Aperture Radar) data not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. We will present some case studies of Asian coastal regions using L-band SAR data, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) and JERS-1 (Japanese Earth Resource Satellite-1) SAR data. One example is that time-series of radar amplitude images can be used to delineate changes quantitatively of the areal extent of river-mouth bars in distributaries of the Mekong River delta. It shows that the estimated areas of river mouthbars gradually increase on an annual time scale, and seasonal variations of areas were also recognized. Another example is that differential SAR interferometry is applied to the coast of the Yellow River delta in China. It shows very high subsidence rates, likely due to groundwater pumping. A further example is that we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain, Thailand. A single reference time series interferogram from the stacking of unwrapped phases were applied. The subsidence and uplift pattern observed using the SAR interferometry time series analysis highlights the spatial complexity

  2. Interferometric synthetic aperture radar study of Okmok volcano, Alaska, 1992-2003: Magma supply dynamics and postemplacement lava flow deformation

    Science.gov (United States)

    Lu, Zhiming; Masterlark, Timothy; Dzurisin, D.

    2005-01-01

    Okmok volcano, located in the central Aleutian arc, Alaska, is a dominantly basaltic complex topped with a 10-km-wide caldera that formed circa 2.05 ka. Okmok erupted several times during the 20th century, most recently in 1997; eruptions in 1945, 1958, and 1997 produced lava flows within the caldera. We used 80 interferometric synthetic aperture radar (InSAR) images (interferograms) to study transient deformation of the volcano before, during, and after the 1997 eruption. Point source models suggest that a magma reservoir at a depth of 3.2 km below sea level, located beneath the center of the caldera and about 5 km northeast of the 1997 vent, is responsible for observed volcano-wide deformation. The preeruption uplift rate decreased from about 10 cm yr-1 during 1992-1993 to 2 ??? 3 cm yr-1 during 1993-1995 and then to about -1 ??? -2 cm yr-1 during 1995-1996. The posteruption inflation rate generally decreased with time during 1997-2001, but increased significantly during 2001-2003. By the summer of 2003, 30 ??? 60% of the magma volume lost from the reservoir in the 1997 eruption had been replenished. Interferograms for periods before the 1997 eruption indicate consistent subsidence of the surface of the 1958 lava flows, most likely due to thermal contraction. Interferograms for periods after the eruption suggest at least four distinct deformation processes: (1) volcano-wide inflation due to replenishment of the shallow magma reservoir, (2) subsidence of the 1997 lava flows, most likely due to thermal contraction, (3) deformation of the 1958 lava flows due to loading by the 1997 flows, and (4) continuing subsidence of 1958 lava flows buried beneath 1997 flows. Our results provide insights into the postemplacement behavior of lava flows and have cautionary implications for the interpretation of inflation patterns at active volcanoes.

  3. Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data

    Science.gov (United States)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Kleynhans, Waldo; Wessels, Konrad; Asner, Gregory; Leblon, Brigitte

    2015-07-01

    Structural parameters of the woody component in African savannahs provide estimates of carbon stocks that are vital to the understanding of fuelwood reserves, which is the primary source of energy for 90% of households in South Africa (80% in Sub-Saharan Africa) and are at risk of over utilisation. The woody component can be characterised by various quantifiable woody structural parameters, such as tree cover, tree height, above ground biomass (AGB) or canopy volume, each been useful for different purposes. In contrast to the limited spatial coverage of ground-based approaches, remote sensing has the ability to sense the high spatio-temporal variability of e.g. woody canopy height, cover and biomass, as well as species diversity and phenological status - a defining but challenging set of characteristics typical of African savannahs. Active remote sensing systems (e.g. Light Detection and Ranging - LiDAR; Synthetic Aperture Radar - SAR), on the other hand, may be more effective in quantifying the savannah woody component because of their ability to sense within-canopy properties of the vegetation and its insensitivity to atmosphere and clouds and shadows. Additionally, the various components of a particular target's structure can be sensed differently with SAR depending on the frequency or wavelength of the sensor being utilised. This study sought to test and compare the accuracy of modelling, in a Random Forest machine learning environment, woody above ground biomass (AGB), canopy cover (CC) and total canopy volume (TCV) in South African savannahs using a combination of X-band (TerraSAR-X), C-band (RADARSAT-2) and L-band (ALOS PALSAR) radar datasets. Training and validation data were derived from airborne LiDAR data to evaluate the SAR modelling accuracies. It was concluded that the L-band SAR frequency was more effective in the modelling of the CC (coefficient of determination or R2 of 0.77), TCV (R2 of 0.79) and AGB (R2 of 0.78) metrics in Southern African

  4. Monitoring Land Subsidence in Arizona Due to Excessive Groundwater Withdrawal Using Interferometric Synthetic Aperture Radar (InSAR) Data

    Science.gov (United States)

    Conway, B. D.

    2014-12-01

    Land subsidence due to excess groundwater overdraft has been an ongoing problem in south-central and southern Arizona since the1940's. The first earth fissure attributed to excessive groundwater withdrawal was discovered in 1946 near Picacho, Arizona. In some areas of the State, groundwater declines of more than 400 feet have resulted in extensive earth fissuring and widespread land subsidence; land subsidence of more than 19 feet has been documented near Phoenix and Eloy. The Arizona Department of Water Resources (ADWR) has been monitoring land subsidence throughout Arizona since 1997 using Interferometric Synthetic Aperture Radar (InSAR) Data and Global Navigation Satellite System Data. The ADWR InSAR program has proven to be a critical resource in monitoring land subsidence throughout Arizona, resulting in the identification of more than twenty-five individual land subsidence features that cover an area of more than 1,200 square miles. The majority of these land subsidence features are a direct result of groundwater declines attributed to groundwater overdraft. Using InSAR data in conjunction with both automated and manual groundwater level datasets, ADWR is able to monitor active land subsidence areas as well as identify other areas that may require additional InSAR monitoring. InSAR data have also proven to be extremely useful in monitoring land surface uplift associated with rising groundwater levels near groundwater recharge facilities. InSAR data can show the impact of the recharged groundwater as the area of uplift extends down gradient from the recharge facility. Some highlights of recent InSAR results include the identification of a new land subsidence feature in the eastern portion of Metropolitan Phoenix where groundwater levels have recently declined; the identification of changes to a floodplain that may be exacerbating recent flooding; seasonal land subsidence and uplift related to seasonal groundwater demands; and the identification of uplift

  5. Automatic change detection in time series of Synthetic Aperture Radar data using a scale-driven approach

    Science.gov (United States)

    Ajadi, O. A.; Meyer, F. J.

    2013-12-01

    Automatic change detection and change classification from Synthetic Aperture Radar (SAR) images is a difficult task mostly due to the high level of speckle noise inherent to SAR data and the highly non-Gaussian nature of the SAR amplitude information. Several approaches were developed in recent years to deal with SAR specific change detection problems from image pairs and time series of images. Despite these considerable efforts, no satisfying solution to this problem has been found so far. In this paper we present a promising new algorithm for change detection from SAR that is based on a multi-scale analysis of a times series of SAR images. Our approach is composed of three steps, including (1) data enhancement and filtering, (2) multi-scale change detection, and (3) time-series analysis of change detection maps. In the data enhancement and filtering step, we first form time-series of ratio images by dividing all SAR images by a reference acquisition to suppress stationary image information and enhance change signatures. Several methods for reference image selection will be discussed in the paper. The generated ratio images are further log-transformed to create near-Gaussian data and to convert the originally multiplicative noise into additive noise. A subsequent fast non-local mean filter is applied to reduce image noise whilst preserving most of the image details. The filtered log-ratio images are then inserted into a multi-scale change detection algorithm that is composed of: (1) a multi-scale decomposition of the input images using a two-dimensional discrete stationary wavelet transform (2D-SWT); (2) a multi-resolution classification into 'change' and 'no-change' areas; and (3) a scale-driven fusion of the classification results. In a final time-series analysis step the multi-temporal change detection maps are analyzed to identify seasonal, gradual, and abrupt changes. The performance of the developed approach will be demonstrated by application to the

  6. (abstract) Characterization of Tree Water Status and Dielectric Constant Changes of North American Boreal Forests in Combination with Synthetic Aperture Radar Remote Sensing

    Science.gov (United States)

    McDonald, K. C.; Zimmerman, R.; Way, J. B.

    1994-01-01

    The occurrence and magnitude of temporal and spatial tree water status changes in the boreal environment were studied in a floodplain forest in Alaska and in four forest types of Central Canada. Under limited water supply conditions from the rooted soil zone in early spring (freeze/thaw transition) and during summer, trees show declining water potentials. Coincidental change in tree water potential, tree transpiration and tree dielectric constant had been observed in previous studies performed in Mediterranean ecotones. If radar is sensitive to chances in tree water status as reflected through changes in dielectric constant, then radar remote sensing could be used to monitor the water status of forests. The SAR imagery is examined to determine the response of the radar backscatter to the ground based observations of the water status of forest canopies. Comparisons are made between stands and also along the large North-South gradient between sites. Data from SAR are used to examine the radar response to canopy physiological state as related to vegetation freeze/thaw and growing season length.

  7. Preliminary results of short term continuous monitoring of an unstable permafrost affected rock slope using a portable, real aperture radar interferometer (GPRI).

    Science.gov (United States)

    Kos, Andrew; Amann, Florian; Strozzi, Tazio; Button, Edward; Rothard, Gerd

    2010-05-01

    A portable real aperture radar interferometer was used to continuously monitor a large unstable rock slope located in the Glarner Alps of Switzerland over a 26 hour period. With an elevation ranging between 2500 and 2800 m.a.s.l., and a north facing aspect, the slope is influenced by permafrost processes. Radar images revealed a larger than previously known area of instability, characterized by several discrete zones of movement. Maximum average displacements were on the order of approx. 0.5mm per hour. The unstable area was delineated by structural features, one of which included open (ice-filled) fractures. A strong radar signature for toppling was observed after 6 hours corresponding to a large rock column leaning approximately 10 degrees towards the radar's line of sight at the top of slope, however, further interpretation of failure mechanisms from the observed displacement field is complicated without additional data due to the heterogeneous nature of the rock mass characteristics and distribution of discrete talus deposits.

  8. A MoLC+MoM-based G0distribution parameter estimation method with application to synthetic aperture radar target detection

    Institute of Scientific and Technical Information of China (English)

    朱正为; 周建江; 郭玉英

    2015-01-01

    The accuracy of background clutter model is a key factor which determines the performance of a constant false alarm rate (CFAR) target detection method. G0 distribution is one of the optimal statistic models in the synthetic aperture radar (SAR) image background clutter modeling and can accurately model various complex background clutters in the SAR images. But the application of the distribution is greatly limited by its disadvantages that the parameter estimation is complex and the local detection threshold is difficult to be obtained. In order to solve the above-mentioned problems, an synthetic aperture radar CFAR target detection method using the logarithmic cumulant (MoLC) + method of moment (MoM)-based G0distribution clutter model is proposed. In the method, G0 distribution is used for modeling the background clutters, a new MoLC+MoM-based parameter estimation method coupled with a fast iterative algorithm is used for estimating the parameters of G0 distribution and an exquisite dichotomy method is used for obtaining the local detection threshold of CFAR detection, which greatly improves the computational efficiency, detection performance and environmental adaptability of CFAR detection. Experimental results show that the proposed SAR CFAR target detection method has good target detection performance in various complex background clutter environments.

  9. Deformation estimation of an earth dam and its relation with local earthquakes, by exploiting multitemporal synthetic aperture radar interferometry: Mornos dam case (Central Greece)

    Science.gov (United States)

    Neokosmidis, Spiros; Elias, Panagiotis; Parcharidis, Issaak; Briole, Pierre

    2016-04-01

    Monitoring dam performance is a critical parameter in maintaining a safe dam. Safety concerns include seepage, internal erosion, and seismic issues in the case that the dam is located in high seismic hazard areas. Seismic considerations for dam safety among others includes the expected dam's performance during seismic events. The scope of this research work concerns the capability to record potential deformation on the Mornos earth dam (central Greece) induced by major earthquake events that occurred in the broader area. For this purpose, a hybrid interferometry synthetic aperture radar (InSAR) method was applied using elements of conventional differential InSAR, short baseline interferometry approaches, and persistent scatterers interferometry. A time series of ascending and descending acquisitions of active microwave instrument/ERS-1 and 2 and advanced synthetic aperture radar/ENVISAT scenes covering the period from 1993 to 2010 were interferometrically combined. Five very strong seismic events with epicenters close to the dam, at the same period, were considered as potential sources of deformation. The lake's water surface elevation was also considered as an additional factor of induced deformation. Results show a maximum deformation rate of ˜10 cm along the line of sight for the whole period. Although the observed deformation appears to be due to changes in water level following a particular pattern, this is interrupted over time, and these interruptions coincide in time with specific seismic events.

  10. Generalized proportional conflict redistribution rule applied to Sonar imagery and Radar targets classification

    CERN Document Server

    Martin, Arnaud

    2008-01-01

    In this chapter, we present two applications in information fusion in order to evaluate the generalized proportional conflict redistribution rule presented in the chapter \\cite{Martin06a}. Most of the time the combination rules are evaluated only on simple examples. We study here different combination rules and compare them in terms of decision on real data. Indeed, in real applications, we need a reliable decision and it is the final results that matter. Two applications are presented here: a fusion of human experts opinions on the kind of underwater sediments depict on sonar image and a classifier fusion for radar targets recognition.

  11. Radar image analysis utilizing junctive image metamorphosis

    Science.gov (United States)

    Krueger, Peter G.; Gouge, Sally B.; Gouge, Jim O.

    1998-09-01

    A feasibility study was initiated to investigate the ability of algorithms developed for medical sonogram image analysis, to be trained for extraction of cartographic information from synthetic aperture radar imagery. BioComputer Research Inc. has applied proprietary `junctive image metamorphosis' algorithms to cancer cell recognition and identification in ultrasound prostate images. These algorithms have been shown to support automatic radar image feature detection and identification. Training set images were used to develop determinants for representative point, line and area features, which were used on test images to identify and localize the features of interest. The software is computationally conservative; operating on a PC platform in real time. The algorithms are robust; having applicability to be trained for feature recognition on any digital imagery, not just those formed from reflected energy, such as sonograms and radar images. Applications include land mass characterization, feature identification, target recognition, and change detection.

  12. Polarimetric C-/X-band Synthetic Aperture Radar Observations of Melting Sea Ice in the Canadian Arctic Archipelago

    Science.gov (United States)

    Casey, J. A.; Beckers, J. F.; Brossier, E.; Haas, C.

    2013-12-01

    Operational ice information services rely heavily on space-borne synthetic aperture radar (SAR) data for the production of ice charts to meet their mandate of providing timely and accurate sea ice information to support safe and efficient marine operations. During the summer melt period, the usefulness of SAR data for sea ice monitoring is limited by the presence of wet snow and melt ponds on the ice surface, which can mask the signature of the underlying ice. This is a critical concern for ice services whose clients (e.g. commercial shipping, cruise tourism, resource exploration and extraction) are most active at this time of year when sea ice is at its minimum extent, concentration and thickness. As a result, there is a need to further quantify the loss of ice information in SAR data during the melt season and to identify what information can still be retrieved about ice surface conditions and melt pond evolution at this time of year. To date the majority of studies have been limited to analysis of single-polarization C-band SAR data. This study will investigate the potential complimentary and unique sea ice information that polarimetric C- and X-band SAR data can provide to supplement the information available from traditional single co-polarized C-band SAR data. A time-series of polarimetric C- and X-band SAR data was acquired over Jones Sound in the Canadian Arctic Archipelago, in the vicinity of the Grise Fiord, Nunavut. Five RADARSAT-2 Wide Fine Quad-pol images and 11 TerraSAR-X StripMap dual-pol (HH/VV) images were acquired. The time-series begins at the onset of melt in early June and extends through advanced melt conditions in late July. Over this period several ponding and drainage events and two snowfall events occurred. Field observations of sea ice properties were collected using an Ice Mass Balance (IMB) buoy, hourly photos from a time-lapse camera deployed on a coastal cliff, and manual in situ measurements of snow thickness and melt pond depth

  13. A New Tool for Intelligent Parallel Processing of Radar/SAR Remotely Sensed Imagery

    Directory of Open Access Journals (Sweden)

    A. Castillo Atoche

    2013-01-01

    Full Text Available A novel parallel tool for large-scale image enhancement/reconstruction and postprocessing of radar/SAR sensor systems is addressed. The proposed parallel tool performs the following intelligent processing steps: image formation, for the application of different system-level effects of image degradation with a particular remote sensing (RS system and simulation of random noising effects, enhancement/reconstruction by employing nonparametric robust high-resolution techniques, and image postprocessing using the fuzzy anisotropic diffusion technique which incorporates a better edge-preserving noise removal effect and faster diffusion process. This innovative tool allows the processing of high-resolution images provided with different radar/SAR sensor systems as required by RS endusers for environmental monitoring, risk prevention, and resource management. To verify the performance implementation of the proposed parallel framework, the processing steps are developed and specifically tested on graphic processing units (GPU, achieving considerable speedups compared to the serial version of the same techniques implemented in C language.

  14. Etude par imagerie radar des pollutions pétrolières

    Directory of Open Access Journals (Sweden)

    G. Rees

    2004-06-01

    Full Text Available En Russie, chaque année, les déversements de pétrole représentent un cinquième de la production totale. Les plus importants se produisent dans le domaine périglaciaire où le milieu naturel est d’une extrême fragilité. Les pipelines sont soumis à de rudes conditions notamment à la corrosion et aux processus cryogéniques. Le risque de rupture augmente en conséquence. La surveillance des déversements d’hydrocarbures, contrainte par l’immensité et la fréquente inaccessibilité du réseau de pipelines, peut être réalisée par le recours à la télédétection. L’objectif de ce travail est de fournir, à travers l’exemple de la catastrophe d’Usinsk (Rép. de Komi survenue en 1994, des outils d’analyse des images radar. Outre leur capacité à s’affranchir du couvert nuageux, les capteurs radar apportent des informations complémentaires à celles fournies par des capteurs optiques. L’exploitation thématique de ces images est rendue difficile par un certain nombre de facteurs perturbateurs tels que les caractéristiques propres du capteur, la direction de visée, la topographie et le phénomène de chatoiement (speckle. Le travail présenté montre le rôle prépondérant joué par ces corrections qui permettent de disposer de données quantitatives comparables d’une date à une autre. La méthode mise au point ici pour le suivi temporel de l’épanchement de pétrole d’Usinsk à partir de trois images radar, est discutée notamment dans ses limites et son aspect opérationnel possible.

  15. A comparison of detection sensitivity between ALTAIR and Arecibo meteor observations: Can high power and large aperture radars detect low velocity meteor head-echoes

    Science.gov (United States)

    Janches, Diego; Close, Sigrid; Fentzke, Jonathan T.

    2008-01-01

    Meteor head-echo observations using High Power and Large Aperture (HPLA) radars have been routinely used for micrometeor studies for over a decade. The head-echo is a signal from the radar-reflective plasma region traveling with the meteoroid and its detection allows for very precise determination of instantaneous meteor altitude, velocity and deceleration. Unlike specular meteor radars (SMR), HPLA radars are diverse instruments when compared one to another. The operating frequencies range from 46 MHz to 1.29 GHz while the antenna configurations changes from 18,000 dipoles in a 300 m×300 m square array, phase arrays of dipoles to single spherical or parabolic dishes of various dimensions. Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34-42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07] recently showed, by utilizing a head-echo plasma-based model, the presence of instrumental biases in the ALTAIR VHF radar system against detecting meteors produced by very small particles (<1 μg) moving at slow (˜20 km/s) velocities due to the low head echo radar cross-section (RCS) associated with these particles. In this paper we apply the same methodology to the Arecibo 430 MHz radar and compare the results with those presented by Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07]. We show that, if the methodology applied by Hunt et al. [Hunt, S.M., Oppenheim, M., Close, S., Brown, P.G., McKeen, F., Minardi, M., 2004. Icarus 168, 34-42] and Close et al. [Close, S., Brown, P., Campbell-Brown, M., Oppenheim, M., Colestock, P., 2007. Icarus, doi: 10.1016/j.icarus.2006.09.07] is accurate, for particles at least 1 μg or heavier, while the bias may exist for the ALTAIR measurements, it does not exist in the Arecibo data due to its greater sensitivity.

  16. Matching of dissimilar radar images using Marr-Hildreth zero crossings

    Science.gov (United States)

    Mcconnell, Ross M.

    1987-01-01

    Two alternatives to the classical method for finding corresponding points in opposite-side synthetic aperture radar imagery are presented. These new methods focus on matching the shapes of large-scale features in the images rather than on correlating high-frequency pixel gray values. One of the methods may be of use in matching radar images to optical images. The large-scale features are extracted using the Marr-Hildreth operator.

  17. Feasibility of using multiplexed SLAR imagery for water resources management and mapping vegetation communities

    Science.gov (United States)

    Drake, B.; Shuchman, R. A.

    1974-01-01

    A two-wavelength (X band and L band) multiplexed synthetic aperture side-looking airborne radar (SLAR), providing parallel- and cross-polarized images, has been tested for application in mapping vegetation and water resources. Indications of the relative heights, densities, surface roughness and other parameters provided by the multiplexed radar imagery can be used to differentiate and map various types of vegetation. The multiplexed SLAR is superior to thermal IR imagery and aerial photography for determining heights of vegetation and water-land boundaries.

  18. Assessment of the Impact of Reservoirs in the Upper Mekong River Using Satellite Radar Altimetry and Remote Sensing Imageries

    Directory of Open Access Journals (Sweden)

    Kuan-Ting Liu

    2016-04-01

    Full Text Available Water level (WL and water volume (WV of surface-water bodies are among the most crucial variables used in water-resources assessment and management. They fluctuate as a result of climatic forcing, and they are considered as indicators of climatic impacts on water resources. Quantifying riverine WL and WV, however, usually requires the availability of timely and continuous in situ data, which could be a challenge for rivers in remote regions, including the Mekong River basin. As one of the most developed rivers in the world, with more than 20 dams built or under construction, Mekong River is in need of a monitoring system that could facilitate basin-scale management of water resources facing future climate change. This study used spaceborne sensors to investigate two dams in the upper Mekong River, Xiaowan and Jinghong Dams within China, to examine river flow dynamics after these dams became operational. We integrated multi-mission satellite radar altimetry (RA, Envisat and Jason-2 and Landsat-5/-7/-8 Thematic Mapper (TM/Enhanced Thematic Mapper plus (ETM+/Operational  Land Imager (OLI optical remote sensing (RS imageries to construct composite WL time series with enhanced spatial resolutions and substantially extended WL data records. An empirical relationship between WL variation and water extent was first established for each dam, and then the combined long-term WL time series from Landsat images are reconstructed for the dams. The R2 between altimetry WL and Landsat water area measurements is >0.95. Next, the Tropical Rainfall Measuring Mission (TRMM data were used to diagnose and determine water variation caused by the precipitation anomaly within the basin. Finally, the impact of hydrologic dynamics caused by the impoundment of the dams is assessed. The discrepancy between satellite-derived WL and available in situ gauge data, in term of root-mean-square error (RMSE is at 2–5 m level. The estimated WV variations derived from combined RA

  19. Vibrating Ground Target Detection and Feature Extraction of One-stationary Bistatic Frequency-modulated Continuous-wave Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Liang Ying

    2015-12-01

    Full Text Available One of the unique characteristics of a ground target is its micro-motion, which can be used for target classification and identification. In this study, methods for vibrating ground target detection and feature extraction of the one-stationary bistatic frequency-modulated continuous-wave Synthetic Aperture Radar (SAR are studied. The Displaced Phase Center Antenna (DPCA technique is adopted to suppress the ground clutter, allowing the ground-vibrating targets to be detected. Analysis of the received signal indicates that the DPCA processing results in a slow time-varying envelope, known as the Slow Time Envelope (STE. The STE has a direct effect on the micro-Doppler time-frequency curve, which therefore cannot be obtained unbroken. Furthermore, vibrating features are extracted by utilizing their relationship with the STE term. Finally, some simulations are provided to validate the theoretical derivation and effectiveness of the proposed extraction method.

  20. Synthetic Aperture Radar Technology Conference, New Mexico State University, Las Cruces, N. Mex., March 8-10, 1978, Proceedings

    Science.gov (United States)

    1978-01-01

    The following aspects of SAR development are discussed: calibration techniques, image simulation and interpretability, antennas, data processing, and system design. Papers are presented on such topics as a postlaunch calibration experiment for the Seasat-A SAR, computer simulation of an orbital SAR system, definition study of the Shuttle Imaging Radar, custom LSI circuits for spaceborne SAR processors, and random sampling adaptively focusing SAR.

  1. FMCW SAR 运动补偿处理技术研究%Analysis of Motion Compensation for FMCW Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    贾高伟; 常文革

    2013-01-01

    The combination of frequency modulated continuous wave (FMCW)and synthetic aperture radar (SAR)leads to the rapid development of the compact ,low-cost ,low power imaging sensors .The model of imaging in the presence of motion error is presented firstly ,based on which the difference of motion compensation between FMCW SAR and pulsed SAR is compared .The in-tegrated processing flow of motion compensation is proposed ,contains the compensation along track and in the line of sight .The ex-perimental FMCW SAR data and focused SAR images verify the feasibility of the proposed method .%调频连续波(Frequency Modulated Continuous Wave ,FMCW )技术与合成孔径雷达(Synthetic Aperture Radar , SAR)技术的结合,促进了小型化、低成本、低功耗、高分辨率成像传感器的发展。本文建立了非理想情况下FMCW SAR的回波信号模型,分析了FMCW SAR运动补偿处理同脉冲体制SAR的区别;提出了完整的三维误差补偿流程,并分别论证了前向运动误差及沿视线方向(Line of Sight ,LOS )方向运动补偿处理方法;文中最后采用FMCW SAR实测数据对所提处理流程进行了验证。

  2. Rupture parameters of the 2003 Zemmouri (Mw 6.8), Algeria, earthquake from joint inversion of interferometric synthetic aperture radar, coastal uplift, and GPS

    Science.gov (United States)

    Belabbes, S.; Wicks, C.; Cakir, Z.; Meghraoui, M.

    2009-01-01

    We study the surface deformation associated with the 21 May 2003 (M w = 6.8) Zemmouri (Algeria) earthquake, the strongest seismic event felt in the Algiers region since 1716. The thrust earthquake mechanism and related surface deformation revealed an average 0.50 m coastal uplift along ??55-km-long coastline. We obtain coseismic interferograms using Envisat advanced synthetic aperture radar (ASAR) (IS2) and RADARSAT standard beam (ST4) data from both the ascending and descending orbits of Envisat satellite, whereas the RADARSAT data proved useful only in the descending mode. While the two RADARSAT interferograms cover the earthquake area, Envisat data cover only the western half of the rupture zone. Although the interferometric synthetic aperture radar (InSAR) coherence in the epicenter area is poor, deformation fringes are observed along the coast in different patches. In the Boumerdes area, the maximum coseismic deformation is indicated by the high gradient of fringes visible in all interferograms in agreement with field measurements (tape, differential GPS, leveling, and GPS). To constrain the earthquake rupture parameters, we model the interferograms and uplift measurements using elastic dislocations on triangular fault patches in an elastic and homogeneous half-space. We invert the coseismic slip using first, a planar surface and second, a curved fault, both constructed from triangular elements using Poly3Dinv program that uses a damped least square minimization. The best fit of InSAR, coastal uplift, and GPS data corresponds to a 65-km-long fault rupture dipping 40?? to 50?? SE, located at 8 to 13 km offshore with a change in strike west of Boumerdes from N60??-65?? to N95??-105??. The inferred rupture geometry at depth correlates well with the seismological results and may have critical implications for the seismic hazard assessment of the Algiers region. Copyright 2009 by the American Geophysical Union.

  3. Rupture parameters of the 2003 Zemmouri (Mw 6.8), Algeria, earthquake from joint inversion of interferometric synthetic aperture radar, coastal uplift, and GPS

    Science.gov (United States)

    BelabbèS, Samir; Wicks, Charles; ćAkir, Ziyadin; Meghraoui, Mustapha

    2009-03-01

    We study the surface deformation associated with the 21 May 2003 (Mw = 6.8) Zemmouri (Algeria) earthquake, the strongest seismic event felt in the Algiers region since 1716. The thrust earthquake mechanism and related surface deformation revealed an average 0.50 m coastal uplift along ˜55-km-long coastline. We obtain coseismic interferograms using Envisat advanced synthetic aperture radar (ASAR) (IS2) and RADARSAT standard beam (ST4) data from both the ascending and descending orbits of Envisat satellite, whereas the RADARSAT data proved useful only in the descending mode. While the two RADARSAT interferograms cover the earthquake area, Envisat data cover only the western half of the rupture zone. Although the interferometric synthetic aperture radar (InSAR) coherence in the epicenter area is poor, deformation fringes are observed along the coast in different patches. In the Boumerdes area, the maximum coseismic deformation is indicated by the high gradient of fringes visible in all interferograms in agreement with field measurements (tape, differential GPS, leveling, and GPS). To constrain the earthquake rupture parameters, we model the interferograms and uplift measurements using elastic dislocations on triangular fault patches in an elastic and homogeneous half-space. We invert the coseismic slip using first, a planar surface and second, a curved fault, both constructed from triangular elements using Poly3Dinv program that uses a damped least square minimization. The best fit of InSAR, coastal uplift, and GPS data corresponds to a 65-km-long fault rupture dipping 40° to 50° SE, located at 8 to 13 km offshore with a change in strike west of Boumerdes from N60°-65° to N95°-105°. The inferred rupture geometry at depth correlates well with the seismological results and may have critical implications for the seismic hazard assessment of the Algiers region.

  4. Gold Mineral Prospecting Using Phased Array Type L-Band Synthetic Aperture Radar (palsar) Satellite Remote Sensing Data, Central Gold Belt, Malaysia

    Science.gov (United States)

    Beiranvand Pour, Amin; Hashim, Mazlan

    2016-06-01

    The Bentong-Raub Suture Zone (BRSZ) of Peninsular Malaysia is one of the significant structural zones in Sundaland, Southeast Asia. It forms the boundary between the Gondwana-derived Sibumasu terrane in the west and Sukhothai arc in the east. The BRSZ is also genetically related to the sediment-hosted/orogenic gold deposits associated with the major lineaments and form-lines in the central gold belt Central Gold Belt of Peninsular Malaysia. In tropical environments, heavy tropical rainforest and intense weathering makes it impossible to map geological structures over long distances. Advances in remote sensing technology allow the application of Synthetic Aperture Radar (SAR) data in geological structural analysis for tropical environments. In this investigation, the Phased Array type L-band Synthetic Aperture Radar (PALSAR) satellite remote sensing data were used to analyse major geological structures in Peninsular Malaysia and provide detailed characterization of lineaments and form-lines in the BRSZ, as well as its implication for sediment-hosted/orogenic gold exploration in tropical environments. The major geological structure directions of the BRSZ are N-S, NNE-SSW, NE-SW and NW-SE, which derived from directional filtering analysis to PALSAR data. The pervasive array of N-S faults in the study area and surrounding terrain is mainly linked to the N-S trending of the Suture Zone. N-S striking lineaments are often cut by younger NE-SW and NW-SE-trending lineaments. Gold mineralized trends lineaments are associated with the intersection of N-S, NE-SW, NNW-SSE and ESE-WNW faults and curvilinear features in shearing and alteration zones. Lineament analysis on PALSAR satellite remote sensing data is a useful tool for detecting the boundary between the Gondwana-derived terranes and major geological features associated with suture zone especially for large inaccessible regions in tropical environments.

  5. Characterizing Land Surface Change and Levee Stability in the Sacramento-San Joaquin Delta Using UAVSAR Radar Imagery

    Science.gov (United States)

    Jones, Cathleen; Bawden, Gerald; Deverel, Steven; Dudas, Joel; Hensley, Scott

    2011-01-01

    The Sacramento-San Joaquin Delta is one of the primary water sources for the state of California and represents a complex geographical area comprised of tidal marshland, levee rimmed islands that are used primarily for agriculture, and urban encroachment. Land subsidence has dropped many of the Delta islands 3 to >7 meters below mean sea level and requires nearly 1700 km of levees to maintain the integrity of the islands and flow of water through the Delta. The current average subsidence rates for each island varies, with 1.23 cm/yr on Sherman Island and 2.2 cm/yr for Bacon Island, as determined by ground-based instruments located at isolated points in the Delta. The Delta's status as the most critical water resource for the state, an endangered ecosystem, and an area continuously threatened with levee breakage from hydrostatic pressure and the danger of earthquakes on several major faults in the San Francisco area make it a focus of monitoring efforts by both the state and national government. This activity is now almost entirely done by ground-based efforts, but the benefits of using remote sensing for wide scale spatial coverage and frequent temporal coverage is obvious. The UAVSAR airborne polarimetric and differential interferometric L-band synthetic aperture radar system has been used to collected monthly images of the Sacramento-San Joaquin Delta and much of the adjacent Suisun Marsh since July 2009 to characterize levee stability, image spatially varied subsidence, and assess how well the UAVSAR performs in an area with widespread agriculture production.

  6. Geometric registration and rectification of spaceborne SAR imagery

    Science.gov (United States)

    Curlander, J. C.; Pang, S. N.

    1982-01-01

    This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.

  7. Airship Sparse Array Antenna Radar Real Aperture Imaging Based on Compressed Sensing and Sparsity in Transform Domain

    OpenAIRE

    Li Liechen; Li Daojing; Huang Pingping

    2016-01-01

    A conformal sparse array based on combined Barker code is designed for airship platform. The performance of the designed array such as signal-to-noise ratio is analyzed. Using the hovering characteristics of the airship, interferometry operation can be applied on the real aperture imaging results of two pulses, which can eliminate the random backscatter phase and make the image sparse in the transform domain. Building the relationship between echo and transform coefficients, the Compressed Se...

  8. Integrating the probability integral method for subsidence prediction and differential synthetic aperture radar interferometry for monitoring mining subsidence in Fengfeng, China

    Science.gov (United States)

    Diao, Xinpeng; Wu, Kan; Zhou, Dawei; Li, Liang

    2016-01-01

    Differential synthetic aperture radar interferometry (D-InSAR) is characterized mainly by high spatial resolution and high accuracy over a wide coverage range. Because of its unique advantages, the technology is widely used for monitoring ground surface deformations. However, in coal mining areas, the ground surface can suffer large-scale collapses in short periods of time, leading to inaccuracies in D-InSAR results and limiting its use for monitoring mining subsidence. We propose a data-processing method that overcomes these disadvantages by combining D-InSAR with the probability integral method used for predicting mining subsidence. Five RadarSat-2 images over Fengfeng coal mine, China, were used to demonstrate the proposed method and assess its effectiveness. Using this method, surface deformation could be monitored over an area of thousands of square kilometers, and more than 50 regions affected by subsidence were identified. For Jiulong mine, nonlinear subsidence cumulative results were obtained for a time period from January 2011 to April 2011, and the maximum subsidence value reached up to 299 mm. Finally, the efficiency and applicability of the proposed method were verified by comparing with data from leveling surveying.

  9. Potential of high-resolution detection and retrieval of precipitation fields from X-band spaceborne Synthetic Aperture Radar over land

    Directory of Open Access Journals (Sweden)

    F. S. Marzano

    2010-09-01

    Full Text Available X-band Synthetic Aperture Radars (X-SARs, able to image the Earth's surface at metric resolution, may provide a unique opportunity to measure rainfall over land with spatial resolution of about few hundred meters, due to the atmospheric moving-target degradation effects. This capability has become very appealing due to the recent launch of several X-SAR satellites, even though several remote sensing issues are still open. This work is devoted to: (i explore the potential of X-band high-resolution detection and retrieval of rainfall fields from space using X-SAR signal backscattering amplitude and interferometric phase; (ii evaluate the effects of spatial resolution degradation by precipitation and inhomogeneous beam filling when comparing to other satellite-based sensors. Our X-SAR analysis of precipitation effects has been carried out using both a TerraSAR-X (TSX case study of Hurricane "Gustav" in 2008 over Mississippi (USA and a COSMO-SkyMed (CSK X-SAR case study of orographic rainfall over Central Italy in 2009. For the TSX case study the near-surface rain rate has been retrieved from the normalized radar cross section by means of a modified regression empirical algorithm (MREA. A relatively simple method to account for the geometric effect of X-SAR observation on estimated rainfall rate and first-order volumetric effects has been developed and applied. The TSX-retrieved rain fields have been compared to those estimated from the Next Generation Weather Radar (NEXRAD in Mobile (AL, USA. The rainfall detection capability of X-SAR has been tested on the CSK case study using the repeat-pass coherence response and qualitatively comparing its signature with ground-based Mt. Midia C-band radar in central Italy. A numerical simulator to represent the effect of the spatial resolution and the antenna pattern of TRMM satellite Precipitation Radar (PR and Microwave Imager (TMI, using high-resolution TSX-retrieved rain images, has been also set up in

  10. Radar imaging

    OpenAIRE

    Borden, Brett; Cheney, Margaret

    2013-01-01

    The article of record as published may be found at http://dx.doi.org/1088/0266-5611/29/5/050301 Because of their ability to operate without regard to day, night or weather conditions, radar systems are ubiquitous in remote sensing operations and are used in a wide variety of commercial and military applications. High resolution radar imaging, however, is a remote sensing subcategory that requires raw radar data to be collected over an artificially extended aperture that is much...

  11. Sensing through the wall imaging using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) radar

    Science.gov (United States)

    Nguyen, Lam; Ressler, Marc; Sichina, Jeffrey

    2008-04-01

    The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR). The radar is capable of penetrating enclosed areas (buildings) and generating SAR imagery. This supports the U.S. Army's need for intelligence on the configuration, content, and human presence inside these enclosed areas. The radar system is mounted on a ground based vehicle traveling along the road and is configured with an array of antennas pointing toward the enclosed areas of interest. This paper will describe an experiment conducted recently at Aberdeen Proving Ground (APG), Maryland. In this paper we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the image techniques used to produce the SAR imagery. Finally, we will present SAR imagery of the building and its internal structure from different viewing directions.

  12. Structural and stratigraphic features and ERS 1 synthetic aperture radar backscatter characteristics of ice growing on shallow lakes in NW Alaska, winter 1991-1992

    Science.gov (United States)

    Jeffries, M. O.; Morris, K.; Weeks, W. F.; Wakabayashi, H.

    1994-11-01

    Changes in ERS 1 C band synthetic aperture radar (SAR) backscatter intensity (σ°) from ice growing on shallow tundra lakes at three locations in NW Alaska are described. Ice core analysis shows that at all lakes on the coast at Barrow the ice, whether floating or frozen to the bottom, includes an inclusion-free layer overlying a layer of ice with tubular bubbles oriented parallel to the direction of growth. The clear ice may also be overlain by a discontinuous layer of bubbly snow ice. Backscatter is low (-16 to -22 dB) at the time of initial ice formation, probably due to the specular nature of the upper and lower ice surfaces causing the radar pulse to be reflected away from the radar. As the ice thickens during the autumn, backscatter rises steadily. Once the ice freezes to the lake bottom, regardless of the presence of forward scattering tubular bubbles, low backscatter values of-17 to -18 dB are caused by absorption of the radar signal in the lake bed. For ice that remains afloat all winter the ice-water interface and the tubular bubbles combine, presumably via an incoherent double-bounce mechanism, to cause maximum backscatter values of the order of -6 to -7 dB. The σ° saturates at -6 to -7 dB before maximum ice thickness and tubular bubble content are attained. A simple ice growth model suggests that the layer of ice with tubular bubbles need be only a few centimeters thick midway through the growth season to cause maximum backscatter from floating ice. During the spring thaw a previously unreported backscatter reversal is observed on the floating and grounded portions of the coastal lakes but not on the lakes farther inland. This reversal may be related to the ice surface topography and wetness plus the effects of a longer, cooler melt period by the coast. Time series of backscatter variations from shallow tundra lakes are a record of (1) the development of tubular bubbles in the ice and, by association, changes in the gas content of the underlying

  13. Radar image preprocessing. [of SEASAT-A SAR data

    Science.gov (United States)

    Frost, V. S.; Stiles, J. A.; Holtzman, J. C.; Held, D. N.

    1980-01-01

    Standard image processing techniques are not applicable to radar images because of the coherent nature of the sensor. Therefore there is a need to develop preprocessing techniques for radar images which will then allow these standard methods to be applied. A random field model for radar image data is developed. This model describes the image data as the result of a multiplicative-convolved process. Standard techniques, those based on additive noise and homomorphic processing are not directly applicable to this class of sensor data. Therefore, a minimum mean square error (MMSE) filter was designed to treat this class of sensor data. The resulting filter was implemented in an adaptive format to account for changes in local statistics and edges. A radar image processing technique which provides the MMSE estimate inside homogeneous areas and tends to preserve edge structure was the result of this study. Digitally correlated Seasat-A synthetic aperture radar (SAR) imagery was used to test the technique.

  14. Volcanic and Tectonic Activity in the Red Sea Region (2004-2013): Insights from Satellite Radar Interferometry and Optical Imagery

    KAUST Repository

    Xu, Wenbin

    2015-04-01

    Studying recent volcanic and tectonic events in the Red Sea region is important for improving our knowledge of the Red Sea plate boundary and for regional geohazard assessments. However, limited information has been available about the past activity due to insufficient in-situ data and remoteness of some of the activity. In this dissertation, I have used satellite remote sensing to derive new information about several recent volcanic and tectonic events in the Red Sea region. I first report on three volcanic eruptions in the southern Red Sea, the 2007-8 Jebel at Tair eruption and the 2011-12 & 2013 Zubair eruptions, which resulted in formation of two new islands. Series of high- resolution optical images were used to map the extent of lava flows and to observe and analyze the growth and destructive processes of the new islands. I used Interferometric Synthetic Aperture Radar (InSAR) data to study the evolution of lava flows, to estimate their volumes, as well as to generate ground displacements maps, which were used to model the dikes that fed the eruptions. I then report on my work of the 2009 Harrat Lunayyir dike intrusion and the 2004 Tabuk earthquake sequence in western Saudi Arabia. I used InSAR observations and stress calculations to study the intruding dike at Harrat Lunayyir, while I combined InSAR data and Bayesian estimation to study the Tabuk earthquake activity. The key findings of the thesis are: 1) The recent volcanic eruptions in the southern Red Sea indicate that the area is magmatically more active than previously acknowledged and that a rifting episode has been taken place in the southern Red Sea; 2) Stress interactions between an ascending dike intrusion and normal faulting on graben-bounding faults above the dike can inhibit vertical propagation of magma towards the surface; 3) InSAR observations can improve locations of shallow earthquakes and fault model uncertainties are useful to associate earthquake activity with mapped faults; 4). The

  15. Retrieval of the ocean wave spectrum in open and thin ice covered ocean waters from ERS Synthetic Aperture Radar images

    International Nuclear Information System (INIS)

    This paper concerns with the task of retrieving ocean wave spectra form imagery provided by space-borne SAR systems such as that on board ERS satellite. SAR imagery of surface wave fields travelling into open ocean and into thin sea ice covers composed of frazil and pancake icefields is considered. The major purpose is to gain insight on how the spectral changes can be related to sea ice properties of geophysical interest such as the thickness. Starting from SAR image cross spectra computed from Single Look Complex (SLC) SAR images, the ocean wave spectrum is retrieved using an inversion procedure based on the gradient descent algorithm. The capability of this method when applied to satellite SAR sensors is investigated. Interest in the SAR image cross spectrum exploitation is twofold: first, the directional properties of the ocean wave spectra are retained; second, external wave information needed to initialize the inversion procedure may be greatly reduced using only information included in the SAR image cross spectrum itself. The main drawback is that the wind waves spectrum could be partly lost and its spectral peak wave number underestimated. An ERS-SAR SLC image acquired on April 10, 1993 over the Greenland Sea was selected as test image. A pair of windows that include open-sea only and sea ice cover, respectively, were selected. The inversions were carried out using different guess wave spectra taken from SAR image cross spectra. Moreover, care was taken to properly handle negative values eventually occurring during the inversion runs. This results in a modification of the gradient descending the technique that is required if a non-negative solution of the wave spectrum is searched for. Results are discussed in view of the possibility of SAR data to detect ocean wave dispersion as a means for the retrieval of ice thickness

  16. Retrieval of the ocean wave spectrum in open and thin ice covered ocean waters from ERS Synthetic Aperture Radar images

    Energy Technology Data Exchange (ETDEWEB)

    De Carolis, G. [Consiglio Nazionale delle Ricerche, Istituto di Tecnologia Informatica Spaziale, Centro di Geodesia Spaziale G. Colombo, Terlecchia, MT (Italy)

    2001-02-01

    This paper concerns with the task of retrieving ocean wave spectra form imagery provided by space-borne SAR systems such as that on board ERS satellite. SAR imagery of surface wave fields travelling into open ocean and into thin sea ice covers composed of frazil and pancake icefields is considered. The major purpose is to gain insight on how the spectral changes can be related to sea ice properties of geophysical interest such as the thickness. Starting from SAR image cross spectra computed from Single Look Complex (SLC) SAR images, the ocean wave spectrum is retrieved using an inversion procedure based on the gradient descent algorithm. The capability of this method when applied to satellite SAR sensors is investigated. Interest in the SAR image cross spectrum exploitation is twofold: first, the directional properties of the ocean wave spectra are retained; second, external wave information needed to initialize the inversion procedure may be greatly reduced using only information included in the SAR image cross spectrum itself. The main drawback is that the wind waves spectrum could be partly lost and its spectral peak wave number underestimated. An ERS-SAR SLC image acquired on April 10, 1993 over the Greenland Sea was selected as test image. A pair of windows that include open-sea only and sea ice cover, respectively, were selected. The inversions were carried out using different guess wave spectra taken from SAR image cross spectra. Moreover, care was taken to properly handle negative values eventually occurring during the inversion runs. This results in a modification of the gradient descending the technique that is required if a non-negative solution of the wave spectrum is searched for. Results are discussed in view of the possibility of SAR data to detect ocean wave dispersion as a means for the retrieval of ice thickness.

  17. Airship Sparse Array Antenna Radar Real Aperture Imaging Based on Compressed Sensing and Sparsity in Transform Domain

    Directory of Open Access Journals (Sweden)

    Li Liechen

    2016-02-01

    Full Text Available A conformal sparse array based on combined Barker code is designed for airship platform. The performance of the designed array such as signal-to-noise ratio is analyzed. Using the hovering characteristics of the airship, interferometry operation can be applied on the real aperture imaging results of two pulses, which can eliminate the random backscatter phase and make the image sparse in the transform domain. Building the relationship between echo and transform coefficients, the Compressed Sensing (CS theory can be introduced to solve the formula and achieving imaging. The image quality of the proposed method can reach the image formed by the full array imaging. The simulation results show the effectiveness of the proposed method.

  18. Current Development in Airborne Repeat-pass Interferometric Synthetic Aperture Radar%机载重轨干涉合成孔径雷达的发展

    Institute of Scientific and Technical Information of China (English)

    钟雪莲; 向茂生; 郭华东; 陈仁元

    2013-01-01

    Because of its agility, flexibility, and accuracy, airborne repeat-pass Interferometric Synthetic Aperture Radar (InSAR) is capable of overcoming the disadvantages of a long revisit time and a low resolution in space-borne SAR interferometry and plays an irreplaceable role in monitoring the deformation of landslides, volcanoes, earthquakes, and so on. In this paper, the history and the worldwide status of the technology of airborne repeat-pass SAR interferometry are reviewed in detail. Then, an analysis of the accuracy of this technology is presented, its key problems in practice are stated, and the related researches in this field are introduced comprehensively. The development trends and the prospects of this technology are also described in this paper. Finally, it is pointed that several issues still need to be studied further for accurate parameter inversion.%机载重轨干涉合成孔径雷达(Interferometric Synthetic Aperture Radar, InSAR)以其系统的灵活性、机动性以及测量的高精度在很大程度上克服了星载重轨干涉SAR重访周期长、分辨率低的问题,在滑坡、火山、地震等地表活动的监测中具有不可替代的作用。该文首先详细回顾了机载重轨干涉SAR技术在国内外的发展历史和现状。然后在对机载重轨干涉SAR精度分析的基础上,对该技术在实际应用中存在的关键性问题进行了深入的分析,全面介绍了该领域相关的研究成果,并对机载重轨干涉SAR的应用前景和发展方向进行了展望。最后指出为提高参数反演的精确性还需要解决的问题。

  19. 合成孔径雷达成像Matlab仿真研究%Study on Matlab simulation of synthetic aperture radar imaging

    Institute of Scientific and Technical Information of China (English)

    宋星秀; 曲毅; 王炳和

    2014-01-01

    计算机仿真是现代雷达研究中的重要技术之一,针对合成孔径雷达(SAR)成像中影响仿真结果的因素,从分析SAR发射信号和回波信号模型出发,运用Matlab软件对SAR的发射波形以及点目标成像进行了仿真,直观地反应了距离多普勒成像算法原理。最终通过仿真分析,总结了SAR成像中影响仿真结果的5项因素,而这5项因素在运用Matlab仿真过程中对成像质量的优劣有着至关重要的影响。%Computer simulation is one of the important technologies in the modern radar study. Aiming at the factor which affects simulation results in synthetic aperture radar(SAR)imaging,Matlab software is used to simulate SAR transmission wave-form and point target imaging to realize the analysis of SAR transmitted signal and echo signal model. It reflected the principle of distance Doppler imaging algorithm intuitively. Based on the simulation analysis,the five factors that affect SAR imaging simulation results are summarized,which has a critical influence on imaging quality in the Matlab simulation process.

  20. Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

    Indian Academy of Sciences (India)

    Nishant Gupta; Tajdarul H Syed; Ashiihrii Athiphro

    2013-10-01

    Coal fires in the Jharia coalfield pose a serious threat to India’s vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10–27.8 mm), low (0–10 mm) and upliftment (−10–0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

  1. Multi-input multi-output frequency-modulated continuous wave synthetic aperture radar system using beat-frequency division waveforms

    International Nuclear Information System (INIS)

    Attention has been paid to lightweight, cost-effective frequency-modulated continuous wave (FMCW) synthetic aperture radar (SAR) in recent years. Though FMCW SAR can operate at high altitude, it is still impracticable for wide swath or high Doppler bandwidth remote sensing because of the dramatic losses of range resolution and processing gain. Moreover, the system sampling rate is too high for real-time processing. All these restrictions caused by the bandwidth loss of the dechirp operation can be relieved by expanding the system sweep cycle. However, the broadening of the sweep cycle decreases the system pulse repetition frequency with azimuth ambiguity, which can be suppressed by exploiting the spatial diversity of multi-input multi-output (MIMO) systems. This paper reports a MIMO-FMCW SAR system using beat-frequency division waveforms. There is a small frequency interval and a large overlap (in frequency) between the orthogonal waveforms. As the frequency interval is much smaller than the signal bandwidth, the echoes that come from different transmitters can be separated by bandpass filtering with little intrapulse interference. Consequently, the applications of FMCW SAR systems can be extended for wider swath or higher Doppler bandwidth remote sensing. Theoretical analysis and simulation results illustrate the feasibility of this system. (paper)

  2. Heterogeneous Fault Mechanisms of the 6 October 2008 MW 6.3 Dangxiong (Tibet Earthquake Using Interferometric Synthetic Aperture Radar Observations

    Directory of Open Access Journals (Sweden)

    Caijun Xu

    2016-03-01

    Full Text Available Most current crustal deformation models do not account for topographic effects, crustal lateral variations, and complex fault geometries. To overcome these limitations, we apply finite element models constrained by interferometric Synthetic Aperture Radar (InSAR images of co-seismic displacements to the 2008 Mw 6.3 Dangxiong earthquake that occurred in Yadong–Gulu rift, southern Tibet. For mountainous plateau environments, InSAR observations are advantageous for studying crustal deformation and crustal medium structure. We evaluate the effect of topography and variations in Poisson’s ratio and elastic moduli on estimation of coseismic deformation from InSAR observations. The results show that coseismic surface displacements are more sensitive to variations in Young’s modulus than to variations in topography and Poisson’s ratio. Therefore, with constant Poisson’s ratio and density, we change the Young’s modulus on each side of the fault to obtain the model that best fits the observations. This is attained when the Young’s moduli in the eastern and western sides of the fault were 2.6 × 1010 Pa and 7.8 × 1010 Pa, respectively. The result is consistent with previous field surveys that the medium on either side of the fault is different.

  3. Multi-input multi-output frequency-modulated continuous wave synthetic aperture radar system using beat-frequency division waveforms

    Science.gov (United States)

    Wang, Jie; Chen, Long-yong; Liang, Xing-dong; Ding, Chi-biao; Hong, Wen; Zhou, Liang-jiang; Dong, Yong-wei; Li, Kun

    2013-07-01

    Attention has been paid to lightweight, cost-effective frequency-modulated continuous wave (FMCW) synthetic aperture radar (SAR) in recent years. Though FMCW SAR can operate at high altitude, it is still impracticable for wide swath or high Doppler bandwidth remote sensing because of the dramatic losses of range resolution and processing gain. Moreover, the system sampling rate is too high for real-time processing. All these restrictions caused by the bandwidth loss of the dechirp operation can be relieved by expanding the system sweep cycle. However, the broadening of the sweep cycle decreases the system pulse repetition frequency with azimuth ambiguity, which can be suppressed by exploiting the spatial diversity of multi-input multi-output (MIMO) systems. This paper reports a MIMO-FMCW SAR system using beat-frequency division waveforms. There is a small frequency interval and a large overlap (in frequency) between the orthogonal waveforms. As the frequency interval is much smaller than the signal bandwidth, the echoes that come from different transmitters can be separated by bandpass filtering with little intrapulse interference. Consequently, the applications of FMCW SAR systems can be extended for wider swath or higher Doppler bandwidth remote sensing. Theoretical analysis and simulation results illustrate the feasibility of this system.

  4. Flood disaster monitoring in Thailand by using a airborne L-band SAR: Polarimetric and interferometry Synthetic Aperture Radar with L-band(Pi-SAR-L)

    Science.gov (United States)

    Kawano, N.; Sobue, S.; Shimada, M.; Ohyoshi, K.

    2012-04-01

    It was heavy rainfall around the northern region of Thailand from July to September 2011, which caused flood disaster to quite wide region of Thailand, it finally reached to the Bangkok central in the end of October 2011. Japan Aerospace Exploration Agency (JAXA) conducted an emergency observation by using a airborne L-band SAR: Polarimetric and interferometry Synthetic Aperture Radar with L-band(Pi-SAR-L) from 5th to 27th November to monitor flood area. Pi-SAR-L has a center frequency of 1271.5 MHz, a band width of 50 MHz, a slant range resolution of 3 m, and an acquisition swath of 15 km on the ground. Pi-SAR-L is boarded on an aircraft of the Gulfstream-II operated by the Diamond Air Service(DAS), Japan, and the Gulfstream-II was ferried to the Chieng-Mai airport in the North Thailand, from Japan. In our presentation, we will show flood area around Bangkok and its variations detected by Pi-SAR-L

  5. Time series synthetic aperture radar interferometry over the multispan cable-stayed Rio-Antirio Bridge (central Greece): achievements and constraints

    Science.gov (United States)

    Parcharidis, Issaak; Foumelis, Michael; Benekos, George; Kourkouli, Penelope; Stamatopoulos, Constantine; Stramondo, Salvatore

    2015-01-01

    The aim of the present study is to monitor by means of multitemporal synthetic aperture radar (SAR) interferometry the stability of the fully suspended cable-stayed Rio-Antirio Bridge (RAB) as well as the ground deformation of its surrounding area. The bridge is located in a region characterized by high hazard susceptibility, therefore, the monitoring of its behavior is of significant interest to mitigate potential risks. Envisat ASAR descending and TerraSAR-X ascending acquisitions were exploited using the persistent scatterer interferometry technique covering the periods 2002 to 2010 and 2010 to 2012, respectively. For both periods, ground displacement rates ranging from -12 to +12 mm/year indicate the absence of a significant deformation source acting during the period of investigation. Of interest is the differential motion pattern between Rio and Antirio for both SAR geometries, signifying the contribution of horizontal motion components, meanwhile allowing the quantification of the relative vertical displacement rates of these regions. For the RAB infrastructure, displacement histories were obtained from TerraSAR-X data analysis only for the stable part of the bridge, namely the viaducts and the four pylons, possibly due to the oscillation of its suspended part and the uncertainty of phase measurements over the pavement. The common behavior of the pylons was confirmed with an overall subsidence between -2 and -3 mm/year. The highest rates were observed for pylons established on specific soil types and were attributed to sediment consolidation.

  6. Ground motion measurement in the Lake Mead area, Nevada, by differential synthetic aperture radar interferometry time series analysis: Probing the lithosphere rheological structure

    Science.gov (United States)

    Cavalié, O.; Doin, M.-P.; Lasserre, C.; Briole, P.

    2007-03-01

    We measure ground motion around the Lake Mead, Nevada, using synthetic aperture radar interferometry. The lake water level has fluctuated through time since impoundment in 1935. To quantify the deformation due to water level variations over the past decade, and to constrain the crust and mantle rheological parameters in the lake area, we analyze 241 interferograms based on 43 ERS images acquired between 1992 and 2002. All interferograms have a high coherence due to arid conditions. Most of them show strong atmospheric artefacts. Tropospheric phase delays are estimated and corrected for each interferogram by analyzing the phase/elevation correlation. Corrections are validated using data from the ERA40 global atmospheric reanalysis. Corrected interferograms are inverted pixel by pixel to solve for the time series of ground motion in the lake area. Temporal smoothing is added to reduce random atmospheric artefacts. The observed deformation is nonlinear in time and spreads over a 50 × 50 km2 area. We observe a 16 mm subsidence between 1995 and 1998 due to an 11 m water level increase, followed by an uplift due to the water level drop after 2000. We model the deformation, taking into account the loading history of the lake since 1935. A simple elastic model with parameters constrained by seismic wave velocities does not explain the amplitude of the observed motion. The two-layer viscoelastic model proposed by Kaufmann and Amelung (2000), with a mantle viscosity of 1018 Pa s, adjusts well the data amplitude and its spatiotemporal shape.

  7. Root mass ratio: index derived by assimilation of synthetic aperture radar and the improved World Food Study model for heavy metal stress monitoring in rice

    Science.gov (United States)

    Liu, Ming; Liu, Xiangnan; Liu, Meiling; Liu, Feng; Jin, Ming; Wu, Ling

    2016-04-01

    Dynamic assessment of heavy metal contamination in crops is essential for food security and the farmland ecological environment. A new index for monitoring heavy metal stress based on the assimilation of synthetic aperture radar (SAR) data and the crop growth model is performed. The improved World Food Study (WOFOST) model was used in this study, which is embedded with two stress factors to improve the accuracy of assimilation. Biomass (BM) values retrieved by SAR data were assimilated into the improved WOFOST model to simulate dry weight of rice roots (WRT), and the root mass ratio (RMR, WRT/BM) was calculated as an index for monitoring heavy metal stress. SAR shows enormous potential for monitoring crop growth status in cloudy area. Compared with other physiological indices, RMR could weaken the weight change of rice caused by other background factors. In the temporal scale, RMR showed a faster significant decrease when the stress was greater. The spatial distribution of RMR and the stress factors exhibited good consistency. These results suggest that RMR derived from the assimilation method based on SAR data and the improved WOFOST model is effective for dynamically monitoring the rice growth status in cloudy regions under heavy metal stress.

  8. Classification of Soil Moisture on Vegetated Earthen Levees Using X and L Band Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Mahrooghy, M.; Aanstoos, J. V.; Hasan, K.; Nobrega, R. A.; Younan, N. H.

    2011-12-01

    Earthen levees protect large areas of land in the US from flooding. Timely inspection and repairs can reduce the potential for catastrophic failures. Changes in spatial and temporal patterns of soil moisture can reveal signs of instability and help identify zones of weakness. Since analytical and empirical models have shown a relationship between SAR backscatter and soil moisture, we are using SAR to classify soil moisture on levees. Estimation of soil moisture from SAR is challenging when the surface has any significant vegetation. For the levee application, the soil is typically covered with a uniform layer of grass. Our methodology is based on a supervised soil moisture classification using a back propagation neural network with four classes of low, medium, high, and very high soil moisture. Our methodology consists of the following steps: 1) segmentation of the levee area from background and exclusion of tree-covered areas; 2) extracting the backscattering and texture features such as GLCM (Grey-Level Co-occurrence Matrix) and wavelet features; 3) training the back propagation neural network classifier; and 4) testing the area of interest and validation of the results using ground truth data. Two sources of SAR imagery are tested with this method: (1) fully polarimetric L-band data from NASA's UAVSAR; and (2) dual-polarimetric X-band data from the German TerraSAR-X satellite. The study area is a 4 km stretch of levee along the lower Mississippi River in the United States. Field data collected simultaneously with image acquisition are utilized for training and validation. Preliminary results show classification accuracies of about 50% for the UAVSAR image and 30% for the TerraSAR-X image in vegetated areas. The figure below shows a soil moisture classification using UAVSAR on April 28, 2011.

  9. 分布式全相参雷达系统时间与相位同步方案研究%Time and Phase Synchronization for Distributed Aperture Coherent Radar

    Institute of Scientific and Technical Information of China (English)

    曾涛; 殷丕磊; 杨小鹏; 范华剑

    2013-01-01

      分布式全相参雷达是一种新体制雷达,它解决了大口径雷达难以机动部署、造价昂贵等问题,是下一代雷达的发展方向,目前实现分布式全相参雷达所面临的关键技术问题是时间同步和相位同步。对此,该文分析了时间同步误差和相位同步误差的来源,建立了相应的数学模型,仿真了同步误差对相参性能的影响,给出了时间同步误差及相位同步误差的指标要求。并基于有线传输的非相关传输方式提出了时间同步方案,基于定标的方式提出了相位同步方案,以分别实现分布式全相参雷达的时间同步和相位同步。该文所提出的分布式全相参雷达同步方案,对于这一新体制雷达的实现具有一定的指导意义。%  As a new radar technology, the distributed aperture coherent radar is expected to be the next generation radar, which is easier to transport and less expensive than the traditional large aperture radar. However, the time synchronization and phase synchronization are key issues to be addressed for the distributed aperture coherent radar. In this paper, the error sources of time synchronization and phase synchronization are analyzed, and the corresponding mathematical models are first derived. Then, the impact of synchronization errors on the coherent performance is simulated, and the accuracy of time and phase synchronization is presented based on the simulation results. Finally, the noncorrelation transmission scheme and the calibration scheme based on the wired transmission are proposed to realize the time and phase synchronization, respectively. Research of the synchronization problem could be very helpful to realize the new radar technology of distributed aperture coherent radar.

  10. Radar geomorphology of coastal and wetland environments

    Science.gov (United States)

    Lewis, A. J.; Macdonald, H. C.

    1973-01-01

    Details regarding the collection of radar imagery over the past ten years are considered together with the geomorphic, geologic, and hydrologic data which have been extracted from radar imagery. Recent investigations were conducted of the Louisiana swamp marsh and the Oregon coast. It was found that radar imagery is a useful tool to the scientist involved in wetland research.

  11. Multiscale modeling for classification of SAR imagery using hybrid EM algorithm and genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    Xianbin Wen; Hua Zhang; Jianguang Zhang; Xu Jiao; Lei Wang

    2009-01-01

    A novel method that hybridizes genetic algorithm (GA) and expectation maximization (EM) algorithm for the classification of syn-thetic aperture radar (SAR) imagery is proposed by the finite Gaussian mixtures model (GMM) and multiscale autoregressive (MAR)model. This algorithm is capable of improving the global optimality and consistency of the classification performance. The experiments on the SAR images show that the proposed algorithm outperforms the standard EM method significantly in classification accuracy.

  12. Une nouvelle r\\`egle de combinaison r\\'epartissant le conflit - Applications en imagerie Sonar et classification de cibles Radar

    CERN Document Server

    Martin, Arnaud

    2008-01-01

    These last years, there were many studies on the problem of the conflict coming from information combination, especially in evidence theory. We can summarise the solutions for manage the conflict into three different approaches: first, we can try to suppress or reduce the conflict before the combination step, secondly, we can manage the conflict in order to give no influence of the conflict in the combination step, and then take into account the conflict in the decision step, thirdly, we can take into account the conflict in the combination step. The first approach is certainly the better, but not always feasible. It is difficult to say which approach is the best between the second and the third. However, the most important is the produced results in applications. We propose here a new combination rule that distributes the conflict proportionally on the element given this conflict. We compare these different combination rules on real data in Sonar imagery and Radar target classification.

  13. Motion Compensation for Airborne Forward Looking Synthetic Aperture Radar with Linear Array Antennas%机载前视阵列SAR运动补偿研究

    Institute of Scientific and Technical Information of China (English)

    张英杰; 王彦平; 谭维贤; 洪文

    2013-01-01

      Combined with Frequency-Modulated Continuous-Wave (FMCW) technology, airborne forward-looking Synthetic Aperture Radar (SAR) with linear array antennas can obtain the images in front of an aircraft, while having the advantages of FMCW radar such as small size and lightweight. Moreover, it is suitable for installation on platforms such as helicopters and small unmanned aerial vehicles. In practice, motion compensation for forward-looking SAR with linear array antennas is one of the key problems to obtaining the images in front of aircraft. This paper uses linear array antennas to analyses the influence of motion error in aircraft on an echo model based on the geometry of forward looking SAR, with linear array antennas, and proposes a motion compensation scheme. Moreover, the compensation scheme is applied to an improved Frequency Scaling Algorithm (FSA) for FMCW forward looking SAR with linear array antennas. Finally, the compensation scheme is verified using simulations.%  结合调频连续波(FMCW)技术的机载前视阵列合成孔径雷达(SAR)既能够获取飞机前下方区域图像,又具有FMCW体制雷达体积小、重量轻的优势,易于安装在直升机等轻小型平台。前视阵列SAR的运动补偿是获得前视图像信息的关键问题之一。该文根据前视阵列SAR的几何模型,分析了载机平台运动误差对回波的影响,研究了相应的运动补偿方法。在此基础上,将补偿方法嵌入到一种基于FMCW的前视阵列SAR的改进频率变标算法(FSA)中。最后通过仿真实验验证了该补偿方法的有效性。

  14. Time-Dependent Deformation at Brady Hot Springs Geothermal Field (Nevada) Measured With Interferometric Synthetic Aperture Radar and Modeled with Multiple Working Hypotheses of Coupled Behavior

    Science.gov (United States)

    Feigl, K. L.; Ali, S. T.; Akerley, J.; Baluyut, E.; Cardiff, M. A.; Davatzes, N. C.; Foxall, W.; Fratta, D.; Kreemer, C.; Mellors, R. J.; Lopeman, J.; Spielman, P.; Wang, H. F.

    2015-12-01

    To measure time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada, we analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014 by five satellite missions, including: ERS-2, Envisat, ALOS, TerraSAR-X, and TanDEM-X. The resulting maps of deformation show an elliptical subsiding area that is ~4 km by ~1.5 km. Its long axis coincides with the strike of the dominant normal-fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, that are probably associated with damaged regions where faults interact via thermal (T), hydrological (H), mechanical (M), and chemical (C) processes. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing high-permeability conduits to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We explore first-order models to calculate the time-dependent deformation fields produced by coupled processes, including: thermal contraction of rock (T-M coupling), decline in pore pressure (H-M coupling), and dissolution of minerals over time (H-C-M coupling). These processes are related to the heterogeneity of hydro-geological and material properties at the site. This work is part of a project entitled "Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology" (PoroTomo) http://geoscience.wisc.edu/feigl/porotomo.

  15. 杂波估计合成孔径雷达RFI抑制方法%An RFI suppressing method of synthetic aperture radar based on clutter estimation

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Radio frequency interference (RFI) has been known to deteriorate imaging quality of the low frequency band synthetic aperture radar (SAR), which effects correct interpretation. For SAR using linear frequency modula⁃tion (LFM) signals, a new RFI suppressing method based on clutter estimation in range frequency domain was pro⁃posed in this paper. The method uses Eigen-decomposition to complete RFI detection and gets maximum likelihood (ML) estimation of clutter intensity for imaging scene by using statistics of the averaged periodogram and the histo⁃gram. After determining spectrum intervals of RFI signals by the judging method of threshold, Wiener filter was ap⁃plied to filter the RFI signals in the range frequency domain. The processing results of L-band SAR data verify the effectiveness of this method.%  射频干扰(RFI)会造成低频段合成孔径雷达(SAR)成像质量恶化,影响正确解译和判读.针对线性调频(LFM)信号的SAR,提出了一种基于距离频谱域杂波估计的RFI抑制方法,采用特征分解完成RFI检测,利用平均周期图和直方图统计得到成像场景杂波强度的最大似然(ML)估计,通过阈值判断方法确定RFI信号的频谱区间后,在距离频域采用维纳滤波器进行RFI信号的滤除.L波段SAR数据的处理结果验证了该方法的有效性.

  16. Graph theory for analyzing pair-wise data: application to geophysical model parameters estimated from interferometric synthetic aperture radar data at Okmok volcano, Alaska

    Science.gov (United States)

    Reinisch, Elena C.; Cardiff, Michael; Feigl, Kurt L.

    2016-07-01

    Graph theory is useful for analyzing time-dependent model parameters estimated from interferometric synthetic aperture radar (InSAR) data in the temporal domain. Plotting acquisition dates (epochs) as vertices and pair-wise interferometric combinations as edges defines an incidence graph. The edge-vertex incidence matrix and the normalized edge Laplacian matrix are factors in the covariance matrix for the pair-wise data. Using empirical measures of residual scatter in the pair-wise observations, we estimate the relative variance at each epoch by inverting the covariance of the pair-wise data. We evaluate the rank deficiency of the corresponding least-squares problem via the edge-vertex incidence matrix. We implement our method in a MATLAB software package called GraphTreeTA available on GitHub (https://github.com/feigl/gipht). We apply temporal adjustment to the data set described in Lu et al. (Geophys Res Solid Earth 110, 2005) at Okmok volcano, Alaska, which erupted most recently in 1997 and 2008. The data set contains 44 differential volumetric changes and uncertainties estimated from interferograms between 1997 and 2004. Estimates show that approximately half of the magma volume lost during the 1997 eruption was recovered by the summer of 2003. Between June 2002 and September 2003, the estimated rate of volumetric increase is (6.2 ± 0.6) × 10^6~m^3/year . Our preferred model provides a reasonable fit that is compatible with viscoelastic relaxation in the five years following the 1997 eruption. Although we demonstrate the approach using volumetric rates of change, our formulation in terms of incidence graphs applies to any quantity derived from pair-wise differences, such as range change, range gradient, or atmospheric delay.

  17. Sinking Coastlines: Land Subsidence at Aquaculture Facilities in the Yellow River Delta, China, measured with Differential Synthetic Aperture Radar (D-InSAR)

    Science.gov (United States)

    Higgins, S.; Overeem, I.; Tanaka, A.; Syvitski, J. P.

    2013-12-01

    Land subsidence in river deltas is a global problem. It heightens storm surges, salinates groundwater, intensifies river flooding, destabilizes infrastructure and accelerates shoreline retreat. Measurements of delta subsidence typically rely on point measures such as GPS devices, tide gauges or extensometers, but spatial coverage is needed to fully assess risk across river deltas. Differential Interferometric Synthetic Aperture Radar (D-InSAR) is a satellite-based technique that can provide maps of ground deformation with mm to cm-scale vertical resolution. We apply D-InSAR to the coast of the Yellow River Delta in China, which is dominated by aquaculture facilities and has experienced severe coastal erosion in the last twenty years. We extract deformation patterns from dry land adjacent to aquaculture facilities along the coast, allowing the first measurements of subsidence at a non-urban delta shoreline. Results show classic cones-of-depression surrounding aquaculture facilities, likely due to groundwater pumping. Subsidence rates are as high as 250 mm/y at the largest facility on the delta. These rates exceed local and global average sea level rise by nearly two orders of magnitude. If these rates continue, large aquaculture facilities in the area could induce more than a meter of relative sea level rise every five years. Given the global explosion in fish farming in recent years, these results also suggest that similar subsidence and associated relative sea level rise may present a significant hazard for other Asian megadeltas. False-color MODIS image of the Yellow River delta in September 2012. Water appears dark blue, highlighting the abundance of aquaculture facilities along the coast. Green land is primarily agricultural; brown is urban. Red boxes indicate locations of aquaculture facilities examined in this study. Figure from Higgins, S., Overeem, I., Tanaka, A., & Syvitski, J.P.M., (2013), Land Subsidence at Aquaculture Facilities in the Yellow River

  18. Wind vector retrieval using dual polarization imagery of ASAR

    Institute of Scientific and Technical Information of China (English)

    SONG Guiting; HOU Yijun; QI Peng

    2006-01-01

    A new algorithm for retrieving wind vector using dual polarization imagery of advanced synthetic aperture radar (ASAR) is developed and tested. Based on the combination of co-polarization and cross-polarization, this new algorithm effectively eliminates the 180° ambiguity which occurs when using single imagery of the ASAR to retrieve wind vector. This algorithm also solves the problem that the retrieval results will break down on very small spatial scales. The results retrieved from dual polarization imagery of ASAR show that the wind speed and direction are in agreement with the data from Quikscat and buoy measurements. The root mean square errors of wind direction and speed between the retrieved results and data from Quikscat are 2.21° and 0.53 m/s, respectively.Comparisons between the new method and the traditional method show that the new methods fit the buoy data and Quikscat data a little better than the traditional method in this image.

  19. Investigation of land subsidence in the Houston-Galveston region of Texas by using the Global Positioning System and interferometric synthetic aperture radar, 1993-2000

    Science.gov (United States)

    Bawden, Gerald W.; Johnson, Michaela R.; Kasmarek, Mark C.; Brandt, Justin; Middleton, Clifton S.

    2012-01-01

    Since the early 1900s, groundwater has been the primary source of municipal, industrial, and agricultural water supplies for the Houston-Galveston region, Texas. The region's combination of hydrogeology and nearly century-long use of groundwater has resulted in one of the largest areas of subsidence in the United States; by 1979, as much as 3 meters (m) of subsidence had occurred, and approximately 8,300 square kilometers of land had subsided more than 0.3 m. The U.S. Geological Survey, in cooperation with the Harris-Galveston Subsidence District, used interferometric synthetic aperture radar (InSAR) data obtained for four overlapping scenes from European remote sensing satellites ERS-1 and ERS-2 to analyze land subsidence in the Houston-Galveston region of Texas. The InSAR data were processed into 27 interferograms that delineate and quantify land-subsidence patterns and magnitudes. Contemporaneous data from the Global Positioning System (GPS) were reprocessed by the National Geodetic Survey and analyzed to support, verify, and provide temporal resolution to the InSAR investigation. The interferograms show that the area of historical subsidence in downtown Houston along the Houston Ship Channel has stabilized and that recent subsidence occurs farther west and north of Galveston Bay. Three areas of recent subsidence were delineated along a broad arcuate (bowshaped) feature from Spring, Tex., southwest to Cypress, Tex., and south to Sugar Land, Tex., with subsidence rates ranging from 15 millimeters per year (mm/yr) to greater than 60 mm/yr. Multiyear interferograms near Seabrook, Tex., within the historical subsidence area and nearby Galveston Bay, show several fringes of subsidence (approximately 85 millimeters from January 1996 to December 1997) in the area; however it is difficult to determine the subsidence magnitude near Seabrook because many of the InSAR fringes were truncated or ill-defined. Horizontal and vertical GPS data throughout the area support the In

  20. The potential of flood forecasting using a variable-resolution global Digital Terrain Model and flood extents from Synthetic Aperture Radar images.

    Science.gov (United States)

    Mason, David; Garcia-Pintado, Javier; Cloke, Hannah; Dance, Sarah

    2015-08-01

    A basic data requirement of a river flood inundation model is a Digital Terrain Model (DTM) of the reach being studied. The scale at which modeling is required determines the accuracy required of the DTM. For modeling floods in urban areas, a high resolution DTM such as that produced by airborne LiDAR (Light Detection And Ranging) is most useful, and large parts of many developed countries have now been mapped using LiDAR. In remoter areas, it is possible to model flooding on a larger scale using a lower resolution DTM, and in the near future the DTM of choice is likely to be that derived from the TanDEM-X Digital Elevation Model (DEM). A variable-resolution global DTM obtained by combining existing high and low resolution data sets would be useful for modeling flood water dynamics globally, at high resolution wherever possible and at lower resolution over larger rivers in remote areas. A further important data resource used in flood modeling is the flood extent, commonly derived from Synthetic Aperture Radar (SAR) images. Flood extents become more useful if they are intersected with the DTM, when water level observations (WLOs) at the flood boundary can be estimated at various points along the river reach. To illustrate the utility of such a global DTM, two examples of recent research involving WLOs at opposite ends of the spatial scale are discussed. The first requires high resolution spatial data, and involves the assimilation of WLOs from a real sequence of high resolution SAR images into a flood model to update the model state with observations over time, and to estimate river discharge and model parameters, including river bathymetry and friction. The results indicate the feasibility of such an Earth Observation-based flood forecasting system. The second example is at a larger scale, and uses SAR-derived WLOs to improve the lower-resolution TanDEM-X DEM in the area covered by the flood extents. The resulting reduction in random height error is significant.

  1. 综合口径雷达的宽频带双极化口径耦合微带阵%Wideband dual-polarized slot-coupled microstrip array for synthetic aperture radar application

    Institute of Scientific and Technical Information of China (English)

    梁仙灵; 钟顺时; 汪伟

    2007-01-01

    An 8×1-element wideband dual-polarized slot-coupled microstrip antenna array with high isolation and low crosspolarization in X-band is presented.The array antenna offers an impedance bandwidth(VSWR≤2)of 23%and 21%for dual polarization ports,respectively.The measured isolation between two polarization ports is better than 35 dB and the measured cross-polarization level below-25 dB in the main beam over the operation frequency band of 9.35 GHz to 9.75 GHz.This array is well suitable for X-band SAR(synthetic aperture radar)antenna application.

  2. Automatic polar ice thickness estimation from SAR imagery

    Science.gov (United States)

    Rahnemoonfar, Maryam; Yari, Masoud; Fox, Geoffrey C.

    2016-05-01

    Global warming has caused serious damage to our environment in recent years. Accelerated loss of ice from Greenland and Antarctica has been observed in recent decades. The melting of polar ice sheets and mountain glaciers has a considerable influence on sea level rise and altering ocean currents, potentially leading to the flooding of the coastal regions and putting millions of people around the world at risk. Synthetic aperture radar (SAR) systems are able to provide relevant information about subsurface structure of polar ice sheets. Manual layer identification is prohibitively tedious and expensive and is not practical for regular, longterm ice-sheet monitoring. Automatic layer finding in noisy radar images is quite challenging due to huge amount of noise, limited resolution and variations in ice layers and bedrock. Here we propose an approach which automatically detects ice surface and bedrock boundaries using distance regularized level set evolution. In this approach the complex topology of ice and bedrock boundary layers can be detected simultaneously by evolving an initial curve in radar imagery. Using a distance regularized term, the regularity of the level set function is intrinsically maintained that solves the reinitialization issues arising from conventional level set approaches. The results are evaluated on a large dataset of airborne radar imagery collected during IceBridge mission over Antarctica and Greenland and show promising results in respect to hand-labeled ground truth.

  3. Synthetic Aperture Radar (SAR) using in the detection of oil spills on the ocean surface, from texture classification at the Campos Basin region, RJ, Brazil; Uso de radar de abertura sintetica na deteccao de manchas de oleo na superficie do mar a partir de classificacao textural na regiao da Bacia de Campos, RJ, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Luciana de Souza [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)]. E-mail: lsoler@ltid.inpe.br; Freitas, Corina da Costa [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Processamento de Imagens]. E-mail: corina@dpi.inpe.br; Lorenzzetti, Joao Antonio [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Oceanografia por Satelite]. E-mail: loren@ltid.inpe.br

    2001-07-01

    The search for oil reserves and oil production along offshore has caused an increase in oil and its derivatives transportation by ships. As a result, the oil spills have showed a serious threat to ocean healthy and preservation. The Synthetic Aperture Radar (SAR) capability in detecting ocean healthy and preservation. The Synthetic Aperture Radar (SAR) capability in detecting ocean surface waves, allows the oil spills identification due the damping of gravity and capillary waves. The wave damping causes allow roughness, thus a low signal return to radar. However, some ocean features, as low wind areas and rain cells (so-called oil spill look-alike), have similar responses to oil spill. This fact is considered the main problem in SAR contribution development in oil spill man made monitoring. It was used 4 RADARSAT/SAR images in Campos Basin, Rio de Janeiro state. Two different textural classifiers were applied to separate oil, water, ships and oil spill look-alike. It was observed that both classifiers had relatively a good performance in separating oil, water and ships. However, in some classifications, it was observed a relative confusion between oil spill and its look-alike due to their similar responses. In spite of this limitation, it was concluded that SAR has a great potential in the oil spill detection in ocean surface. (author)

  4. Validation and Sensitivity Analysis of 3D Synthetic Aperture Radar (SAR) Imaging of the Interior of Primitive Solar System Bodies: Comets and Asteroids Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To probe the interior of a comet, we are going to employ Radar Reflection Imager (RRI) Instrument on an orbiting platform. While orbiting around the comet at a safe...

  5. Integrating Radar Image Data with Google Maps

    Science.gov (United States)

    Chapman, Bruce D.; Gibas, Sarah

    2010-01-01

    A public Web site has been developed as a method for displaying the multitude of radar imagery collected by NASA s Airborne Synthetic Aperture Radar (AIRSAR) instrument during its 16-year mission. Utilizing NASA s internal AIRSAR site, the new Web site features more sophisticated visualization tools that enable the general public to have access to these images. The site was originally maintained at NASA on six computers: one that held the Oracle database, two that took care of the software for the interactive map, and three that were for the Web site itself. Several tasks were involved in moving this complicated setup to just one computer. First, the AIRSAR database was migrated from Oracle to MySQL. Then the back-end of the AIRSAR Web site was updated in order to access the MySQL database. To do this, a few of the scripts needed to be modified; specifically three Perl scripts that query that database. The database connections were then updated from Oracle to MySQL, numerous syntax errors were corrected, and a query was implemented that replaced one of the stored Oracle procedures. Lastly, the interactive map was designed, implemented, and tested so that users could easily browse and access the radar imagery through the Google Maps interface.

  6. Antenna motion errors in bistatic SAR imagery

    Science.gov (United States)

    Wang, Ling; Yazıcı, Birsen; Cagri Yanik, H.

    2015-06-01

    Antenna trajectory or motion errors are pervasive in synthetic aperture radar (SAR) imaging. Motion errors typically result in smearing and positioning errors in SAR images. Understanding the relationship between the trajectory errors and position errors in reconstructed images is essential in forming focused SAR images. Existing studies on the effect of antenna motion errors are limited to certain geometries, trajectory error models or monostatic SAR configuration. In this paper, we present an analysis of position errors in bistatic SAR imagery due to antenna motion errors. Bistatic SAR imagery is becoming increasingly important in the context of passive imaging and multi-sensor imaging. Our analysis provides an explicit quantitative relationship between the trajectory errors and the positioning errors in bistatic SAR images. The analysis is applicable to arbitrary trajectory errors and arbitrary imaging geometries including wide apertures and large scenes. We present extensive numerical simulations to validate the analysis and to illustrate the results in commonly used bistatic configurations and certain trajectory error models.

  7. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    Science.gov (United States)

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    With the rapid development of spaceborne synthetic aperture radar (SAR) and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way. PMID:27563902

  8. Integration of Optical and Synthetic Aperture Radar Imagery for Improving Crop Mapping in Northwestern Benin, West Africa

    Directory of Open Access Journals (Sweden)

    Gerald Forkuor

    2014-07-01

    Full Text Available Crop mapping in West Africa is challenging, due to the unavailability of adequate satellite images (as a result of excessive cloud cover, small agricultural fields and a heterogeneous landscape. To address this challenge, we integrated high spatial resolution multi-temporal optical (RapidEye and dual polarized (VV/VH SAR (TerraSAR-X data to map crops and crop groups in northwestern Benin using the random forest classification algorithm. The overall goal was to ascertain the contribution of the SAR data to crop mapping in the region. A per-pixel classification result was overlaid with vector field boundaries derived from image segmentation, and a crop type was determined for each field based on the modal class within the field. A per-field accuracy assessment was conducted by comparing the final classification result with reference data derived from a field campaign. Results indicate that the integration of RapidEye and TerraSAR-X data improved classification accuracy by 10%–15% over the use of RapidEye only. The VV polarization was found to better discriminate crop types than the VH polarization. The research has shown that if optical and SAR data are available for the whole cropping season, classification accuracies of up to 75% are achievable.

  9. Detection and Measurement of Land Subsidence Using Global Positioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996-2005

    Science.gov (United States)

    Sneed, Michelle; Brandt, Justin T.

    2007-01-01

    Land subsidence associated with ground-water-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Ground water has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and interferometric synthetic aperture radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley. GPS measurements made at 13 geodetic monuments in 1996 and in 2005 in the southern Coachella Valley indicate that the elevation of the land surface had a net decline of 333 to 22 millimeters ?58 millimeters (1.1 to 0.07 foot ?0.19 foot) during the 9-year period. Changes at 10 of the 13 monuments exceeded the maximum uncertainty of ?58 millimeters (?0.19 foot) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2005. GPS measurements made at 20 geodetic monuments in 2000 and in 2005 indicate that the elevation of the land surface changed -312 to +25 millimeters ?42 millimeters (-1.0 to +0.08 foot ?0.14 foot) during the 5-year period. Changes at 14 of the 20 monuments exceeded the maximum uncertainty of ?42 millimeters (?0.14 foot) at the 95-percent confidence level, indicating that subsidence occurred at

  10. Study on the Real Time Imaging Algorithm for Frequency Modulated Continuous Wave Synthetic Aperture Radar%调频连续波SAR实时成像算法研究

    Institute of Scientific and Technical Information of China (English)

    贾高伟; 常文革

    2013-01-01

    The combination of Frequency Modulation Continuous Wave (FMCW) and Synthetic Aperture Radar (SAR) leads to the rapid development of a compact, low power consumption, cheap and high resolution imaging sensor. A corrected signal model of FMCW SAR is built in this paper which forms the basis for the following study. The generalized expression of FMCW SAR algorithms in frequency domain is derived. For the sake of reduce the computation, a simplified imaging flow with motion compensation operation is proposed and the errors introduced by the simplification is analyzed in detail. Finally, the simulated FMCW SAR data verify the feasibility of proposed method.%调频连续波(Frequency Modulation Continuous Wave, FMCW)体制与合成孔径雷达(Synthetic Aperture Radar, SAR)的结合,推动了小型化、低功耗、低成本、高分辨率成像雷达的快速发展。该文建立了FMCW SAR的信号模型,统一了FMCW SAR频域算法的理论表达;结合运动补偿处理,以减小系统计算量为出发点,提出了一种简化的实时成像流程,并在理论上对简化过程引入的相位误差做出细致的理论与量化分析。仿真实验验证了该文所提简化流程的适用性。

  11. Use of the SAR (Synthetic Aperture Radar) P band for detection of the Moche and Lambayeque canal networks in the Apurlec region, Perù

    Science.gov (United States)

    Ilaria Pannaccione Apa, Maria; Santovito, Maria Rosaria; Pica, Giulia; Catapano, Ilaria; Fornaro, Gianfranco; Lanari, Riccardo; Soldovieri, Francesco; Wester La Torre, Carlos; Fernandez Manayalle, Marco Antonio; Longo, Francesco; Facchinetti, Claudia; Formaro, Roberto

    2016-04-01

    In recent years, research attention has been devoted to the development of a new class of airborne radar systems using low frequency bands ranging from VHF/UHF to P and L ones. In this frame, the Italian Space Agency (ASI) has promoted the development of a new multi-mode and multi-band airborne radar system, which can be considered even a "proof-of-concept" for the next space-borne missions. In particular, in agreement with the ASI, the research consortium CO.RI.S.T.A. has in charge the design, development and flight validation of such a kind of system, which is the first airborne radar entirely built in Italy. The aim was to design and realize a radar system able to work in different modalities as: nadir-looking sounder at VHF band (163 MHz); side-looking imager (SAR) at P band with two channels at 450 MHz and 900 MHz. The P-band is a penetration radar. Exploiting penetration features of low frequency electromagnetic waves, dielectric discontinuities of observed scene due to inhomogeneous materials rise up and can be detected on the resulting image. Therefore buried objects or targets placed under vegetation may be detected. Penetration capabilities essentially depend on microwave frequency. Typically, penetration distance is inversely proportional to microwave frequency. The higher the frequency, the lower the penetration depth. Terrain characteristics affect penetration capabilities. Humidity acts as a shield to microwave penetration. Hence terrain with high water content are not good targets for P-band applicability. Science community, governments and space agencies have increased their interest about low frequency radar for their useful applicability in climatology, ecosystem monitoring, glaciology, archaeology. The combination of low frequency and high relative bandwidth of such a systems has a large applicability in both military and civilian applications, ranging from forestry applications, biomass measuring, archaeological and geological exploration

  12. Use of synthetic aperture radar for recognition of Coastal Geomorphological Features, land-use assessment and shoreline changes in Bragança coast, Pará, Northern Brazil

    Directory of Open Access Journals (Sweden)

    Souza-Filho Pedro W. M.

    2003-01-01

    Full Text Available Synthetic Aperture Radar (SAR images are being used more extensively than ever before for geoscience applications in the moist tropics. In this investigation, a RADARSAT1-1 C-HH SAR image acquired in 1998 was used for coastal mapping and land-cover assessment in the Bragança area, in the northern Brazil. The airborne GEMS 1000 X-HH radar image acquired in 1972 during the RADAM Project was also used for evaluating coastal changes occurring over the last three decades. The research has confirmed the usefulness of RADARSAT-1 image for geomorphological mapping and land-cover assessment, particularly in macrotidal mangrove coasts. It was possible to map mangroves, salt marshes, chenier sand ridges, dunes, barrier-beach ridges, shallow water morphologies and different forms of land-use. Furthermore, a new method to estimate shoreline changes based on the superimposition of vectors extracted from both sources of SAR data has indicated that the shoreline has been subjected to severe coastal erosion responsible for retreat of 32 km² and accretion of 20 km², resulting in a mangrove land loss of almost 12 km². In an application perspective, orbital and airborne SAR data proved to be a fundamental source of information for both geomorphological mapping and monitoring coastal changes in moist tropical environments.

  13. The use of radar for bathymetry assessment

    NARCIS (Netherlands)

    Aardoom, J.H.; Greidanus, H.S.F.

    1998-01-01

    The bottom topography in shallow seas can be observed by air- and spaceborne imaging radar. Bathymetric information derived from radar data is limited in accuracy, but radar has a good spatial coverage. The accuracy can be increased by assimilating the radar imagery into existing or insitu gathered

  14. Timely Low Resolution SAR Imagery To Support Floodplain Modelling: a Case Study Review

    Science.gov (United States)

    di Baldassarre, Giuliano; Schumann, Guy; Brandimarte, Luigia; Bates, Paul

    2011-05-01

    It is widely recognised that remote sensing can support flood monitoring, modelling and management. In particular, satellites carrying Synthetic Aperture Radar (SAR) sensors are valuable as radar wavelengths can penetrate cloud cover and are insensitive to daylight. However, given the strong inverse relationship between spatial resolution and revisit time, monitoring floods from space in near real time is currently only possible through low resolution (about 100 m pixel size) SAR imagery. For instance, ENVISAT-ASAR (Advanced Synthetic Aperture Radar) in WSM (wide swath mode) revisit times are of the order of 3 days and the data can be obtained within 24 h at no (or low) cost. Hence, this type of space-borne data can be used for monitoring major floods on medium-to-large rivers. This paper aims to discuss the potential for, and uncertainties of, coarse resolution SAR imagery to monitor floods and support hydraulic modelling. The paper first describes the potential of globally and freely available space-borne data to support flood inundation modelling in near real time. Then, the uncertainty of SAR-derived flood extent maps is discussed and the need to move from deterministic binary maps (wet/dry) of flood extent to uncertain flood inundation maps is highlighted.

  15. Space Radar Image of Central Sumatra, Indonesia

    Science.gov (United States)

    1994-01-01

    This is a radar image of the central part of the island of Sumatra in Indonesia that shows how the tropical rainforest typical of this country is being impacted by human activity. Native forest appears in green in this image, while prominent pink areas represent places where the native forest has been cleared. The large rectangular areas have been cleared for palm oil plantations. The bright pink zones are areas that have been cleared since 1989, while the dark pink zones are areas that were cleared before 1989. These radar data were processed as part of an effort to assist oil and gas companies working in the area to assess the environmental impact of both their drilling operations and the activities of the local population. Radar images are useful in these areas because heavy cloud cover and the persistent smoke and haze associated with deforestation have prevented usable visible-light imagery from being acquired since 1989. The dark shapes in the upper right (northeast) corner of the image are a chain of lakes in flat coastal marshes. This image was acquired in October 1994 by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. Environmental changes can be easily documented by comparing this image with visible-light data that were acquired in previous years by the Landsat satellite. The image is centered at 0.9 degrees north latitude and 101.3 degrees east longitude. The area shown is 50 kilometers by 100 kilometers (31 miles by 62 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is L-band vertically transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  16. Change detection using the synchronous impulse reconstruction (SIRE) radar

    Science.gov (United States)

    Ranney, Kenneth; Nguyen, Lam; Ressler, Marc; Stanton, Brian; Wong, David; Koenig, Francois; Tran, Chi; Kirose, Getachew; Martone, Anthony; Smith, Greg; Sichina, Jeff; Kappra, Karl

    2008-04-01

    Change detection provides a powerful tool for detecting the introduction of weapons or hazardous materials into an area under surveillance, as demonstrated in past work carried out at the Army Research Laboratory (ARL). This earlier work demonstrated the potential for detecting recently emplaced surface landmines using an X-Band, synthetic aperture radar (SAR) sensor. Recent experiments conducted at ARL have extended these change detection results to imagery collected by the synthetic impulse reconstruction (SIRE) radar - a lower-frequency system developed at ARL. In this paper we describe the algorithms adopted for this change detection experiment and present results obtained by applying these algorithms to the SIRE data set. Results indicate the potential for utilizing systems such as the SIRE as surveillance tools.

  17. Separation of ocean features from multifrequency full-polarization SAR imagery

    Institute of Scientific and Technical Information of China (English)

    YANG Jingsong; XIAO Qingmei; HUANG Weigen; FU Bin; CHEN Peng

    2008-01-01

    Different ocean features usually appear in synthetic aperture radar (SAR) images simultaneously. This makes the image compli- cated and hard to understand. Because of lower signal-to-noise rate , it is much more difficult to separate different ocean features than to separate different land features. A completely novel method is presented to separate ocean features from multifrequency po- larimetric SAR imagery. AIRSAR data from Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA) are used in the case studies and good results are achieved.

  18. Wind Atlas for the Gulf of Suez Satellite Imagery and Analyses

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay

    Satellite imagery and data have been used to investigate the spatial distributions of wind speed and some terrain surface characteristics in the Gulf of Suez. The methods and the results are described in three separate sections: 1. “Comparing SAR winds and in-situ winds”. Synthetic Aperture Radar...... classification maps. 3. “Reporting on satellite information for the Wind Atlas for Egypt”. Along-Track Scanning Radiometer (ATSR) data from the European Remote Sensing Satellite (ERS) have been used to map the sea- and land-surface temperatures and albedos....

  19. Dome growth at Mount Cleveland, Aleutian Arc, quantified by time-series TerraSAR-X imagery

    Science.gov (United States)

    Wang, Teng; Poland, Michael; Lu, Zhong

    2016-01-01

    Synthetic aperture radar imagery is widely used to study surface deformation induced by volcanic activity; however, it is rarely applied to quantify the evolution of lava domes, which is important for understanding hazards and magmatic system characteristics. We studied dome formation associated with eruptive activity at Mount Cleveland, Aleutian Volcanic Arc, in 2011–2012 using TerraSAR-X imagery. Interferometry and offset tracking show no consistent deformation and only motion of the crater rim, suggesting that ascending magma may pass through a preexisting conduit system without causing appreciable surface deformation. Amplitude imagery has proven useful for quantifying rates of vertical and areal growth of the lava dome within the crater from formation to removal by explosive activity to rebirth. We expect that this approach can be applied at other volcanoes that host growing lava domes and where hazards are highly dependent on dome geometry and growth rates.

  20. Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery.

    Science.gov (United States)

    Marapareddy, Ramakalavathi; Aanstoos, James V; Younan, Nicolas H

    2016-01-01

    Fully polarimetric Synthetic Aperture Radar (polSAR) data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR) to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H), anisotropy (A), alpha (α), and eigenvalues (λ, λ₁, λ₂, and λ₃), we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory's (JPL's) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers. PMID:27322270

  1. Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery

    Directory of Open Access Journals (Sweden)

    Ramakalavathi Marapareddy

    2016-06-01

    Full Text Available Fully polarimetric Synthetic Aperture Radar (polSAR data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H, anisotropy (A, alpha (α, and eigenvalues (λ, λ1, λ2, and λ3, we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory’s (JPL’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR. The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers.

  2. Ionospheric Effects on Spaceborne P Band Synthetic Aperture Radar Imaging%电离层对星载P波段合成孔径雷达成像的影响

    Institute of Scientific and Technical Information of China (English)

    姚佰栋; 时晶晶

    2015-01-01

    This paper analyzed the relationship between the signal’s carrier frequency, bandwidth, the ionospheric total electronics content(TEC) and scintillation intensity with P band synthetic aperture radar(SAR)’s image resolution. The point target imaging simulation results shown that SAR’s range resolution was closely related with the signal’s carrier frequency, bandwidth and the ionospheric TEC when the wave propagated in the ionosphere, and the ionosphere also caused the SAR image offset in range direction. In addition the azimuth resolution is mainly inlfuenced by the ionospheric scintillation effect, the azimuth resolution decreased rapidly with the enhancement of scintillation’s intensity. While in strong scintillation conditions, the azimuth resolution declined seriously, even could not image.%文章分析了信号载频、带宽、电离层总电子量(Total Electronics Content,TEC)以及闪烁强度等因素对于P波段合成孔径雷达(Synthetic Aperture Radar,SAR)成像分辨率的影响,并进行了点目标成像仿真研究。仿真结果表明,在电离层中传播时SAR距离向分辨率与信号载频、带宽以及电离层总电子量大小密切相关,同时会导致SAR距离向图像偏移;方位向分辨率受电离层闪烁效应的影响,随着闪烁强度的增强,方位向分辨率逐渐降低,当处于强闪烁条件下时,方位向无法成像。

  3. Radar foundations for imaging and advanced concepts

    CERN Document Server

    Sullivan, Roger

    2004-01-01

    Through courses internally taught at IDA, Dr. Roger Sullivan has devised a book that brings readers fully up to speed on the most essential quantitave aspects of general radar in order to introduce study of the most exciting and relevant applications to radar imaging and advanced concepts: Synthetic Aperture Radar (4 chapters), Space-time Adaptive Processing, moving target indication (MTI), bistatic radar, low probability of intercept (LPI) radar, weather radar, and ground-penetrating radar. Whether you're a radar novice or experienced professional, this is an essential refer

  4. Frequency notching effects on GPR imagery while operating in crowded spectrum scenarios

    Science.gov (United States)

    Phelan, Brian R.; Ressler, Marc A.; Ranney, Kenneth I.; Smith, Gregory D.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2016-05-01

    Over the past decade, the radio frequency (RF) spectrum in which radar, telecommunication, navigational, and other systems operate has become increasingly crowded. The Army Research Laboratory has developed a Stepped-Frequency Radar (SFR) which can avoid areas of the RF spectrum in which systems are already operating. This allows for mitigation of RF interference (RFI) on the radar, as well as reduction in the interference from the radar that might affect other systems. This paper addresses the impact of frequency notching on GPR imagery, and methods of mitigating negative effects. The SFR operates over 300-2000 MHz, with a minimum frequency step size of 1 MHz. The radar transmits and receives in pulsed intervals, allowing for receiver blanking of close-in targets. The SFR is vehicle mounted and utilizes two dualpolarized transmit (Tx) horn antennas on either side of the receiver (Rx) antenna aperture, which consists of 16 Vivaldi notch antennas (which can be rotated to either H or V polarization). The radar is capable of completing a sweep over its entire operating band in data collection time.

  5. 星载合成孔径雷达不同工作模式下的PRF优化选取研究%Optimal selection of PRF for spaceborne synthetic aperture radar in different working mode

    Institute of Scientific and Technical Information of China (English)

    陈颖颖; 高阳; 何永华

    2012-01-01

    PRF is an important parameter in spaceborne synthetic aperture radar, which is affected by many factors, especially by emission interference, substellar point echo wave, range ambiguity and azimuth ambiguity. For these factors, the choice of the PRF is variant. On the basis of selecting PRF in common working mode, the selection of PRF in spotlight mode and sliding spotlight mode is discussed. The selection method of the PRF is proposed. At last, the simulation presents the method s effectiveness.%星载合成孔径雷达中,脉冲重复频率(PRF)是非常重要的参数.它的选择受到很多因素的影响,尤其是受到发射干扰、星下点回波、距离模糊以及方位模糊的影响,也正是受到这些因素的影响,导致在不同的工作模式下,PRF的选取有很大的差异.这里在研究常用的条带工作模式下PRF选取的基础上,讨论了聚束和滑动聚束模式下PRF选取的特殊性,给出了这两种工作模式下PRF选取的方法,并进行了仿真验证其有效性.

  6. 前向散射阴影逆合成孔径雷达成像误差分析%Analysis of Forward Scattering Shadow Inverse Synthetic Aperture Radar Imaging Algorithm

    Institute of Scientific and Technical Information of China (English)

    胡程; 周超

    2013-01-01

      阴影逆合成孔径雷达(SISAR)成像算法可以从前向散射雷达(FSR)目标回波中提取目标侧影轮廓像,其成像精度由目标的运动轨迹跟踪精度决定。该文基于小衍射角前向散射信号模型,解析推导了SISAR成像误差与目标运动轨迹跟踪误差的关系;分析了跟踪误差对目标侧影轮廓高度差和中线成像结果的影响,给出了对跟踪精度的定量要求。通过大量仿真验证了分析的正确性。%Shadow Inverse Synthetic Aperture Radar (SISAR) imaging algorithm is a kind of technology to extract the profile of a target from the forward scattering signal. The imaging accuracy depends on the target coordinate estimation precision. In this paper, the relationship between the imaging error and coordinate estimation errors is analytically derived with the forward scattering signal model under the assumption of small diffraction angles. The quantitative requirements for coordinate estimation precision are made. Finally, impacts of coordinate estimation errors on SISAR imaging accuracy are verified via simulation results.

  7. Aircraft radar antennas

    Science.gov (United States)

    Schrank, Helmut E.

    1987-04-01

    Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance antennas is illustrated by the AN/APY-1 Airborne Warning and Control System (AWACS) slotted waveguide array, which achieved a significant breakthrough in sidelobe suppression. Gimballed flat plate arrays in nose radomes are typified by the AN/APG-66 (F-16) antenna. Multifunction phased arrays are presented by the Electronically Agile Radar (EAR) antenna, which has achieved significant advances in performance versatility and reliability. Trends toward active aperture, adaptive, and digital beamforming arrays are briefly discussed. Antennas for future aircraft radar systems must provide multiple functions in less aperture space, and must perform more reliably.

  8. Synthetic Aperture Techniques for Sonar Systems

    OpenAIRE

    Silva, S&#;rgio Rui; Cunha, S&#;rgio; Matos, An&#;bal; Cruz, Nuno

    2009-01-01

    As demonstrated, synthetic aperture sonar is a technique that enables attainment of high quality, high resolution underwater images. Autonomous surface vehicles provides several advantages for synthetic aperture imagery. Not only it is possible to control the boat motion in this way, it is also possible to obtain navigation measurements with precisions in the order of the wavelength used in high resolution sonar systems. Furthermore unsupervised surveillance applications that combine the high...

  9. Wave directional spectrum from SAR imagery

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.; Vethamony, P.

    wave like features, the latter appearing to be of "white noise" nature. There exists a 180 degrees ambiguity in wave direction observed from radar imageries. Based on the method of Atanassov et al (1985), a computer program has been developed...

  10. Radar manifestations of ship wakes in algae bloom zones

    Science.gov (United States)

    Mityagina, Marina I.; Lavrova, Olga Yu.

    2014-10-01

    Radar manifestations of ship wakes in zones of phytoplankton bloom are discussed. It is shown that these signatures can be regarded as indicators of biogenic activity. The main data are satellite radar images. Satellite visible (VIS) and infrared (IR) satellite data are also analyzed. The large amount of the available data allowed us to make some generalizations and obtain statistically reliable results concerning spatial and temporal variability of certain type of ship wake manifestations in synthetic aperture radar (SAR) images of the sea surface. Traditional classification of surface ship wakes manifestations in satellite SAR images specifies distinct features such as a dark trailing centreline region (turbulent wake), narrow V-wakes aligned at some angle to the ship's path (the Kelvin wake), and, sometimes, internal wave wakes generated under conditions of shallow stratification. Their characteristic lengths are reported to be up to tens of kilometers and they can last from tens of minutes up to one hour. Instances of radar signatures of the ship wakes dissimilar to the previously described were detected in radar images obtained in the course of a satellite monitoring campaign of the central and south-eastern Baltic. These ship wakes can be seen in satellite radar images as long bright strips of enhanced backscatter with characteristic length of up to several hundred kilometres lasting more than 5 hours. A hypothesis is put forward of the coherence of this type of ship wakes detected in sea surface radar imagery and areas of intensive biogenic activity under conditions of low near-surface winds. Statistics on their seasonal, spatial and year-to-year distribution are drawn. These results are compared with temporal and spatial variations in chlorophyll a concentration and intensity of phytoplankton bloom in the area of interest. Chlorophyll a concentration maps derived from satellite data are used, as well as those based on in situ measurements. The relation

  11. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  12. 合成孔径雷达数据减灾应用潜力研究综述%Review on Disaster Reduction Application Potentiality of Synthetic Aperture Radar

    Institute of Scientific and Technical Information of China (English)

    张薇; 杨思全; 王磊; 李岩

    2012-01-01

    Synthetic Aperture Radar(SAR)is an active earth observation technology, has been widely used in disaster reduction field at home and abroad. "Environment and disaster monitoring and prediction small sat- ellite constellation" of HJ-1C is the first civil SAR satellite,and is the first satellite used for disaster reduc- tion and relief field in china, has been lauched successfully on November 19,2012. Before launching, from the SAR technical characteristics,this paper analyzes the application situation and potentiality of SAR data divided into single-polarization SAR, multi-polarization SAR, Interferometric SAR and Polarimetric SAR Interferometry. This study has important significance in promoting deeper development of disaster monito- ring and warning business system by SAR technique, driving application of high space technique and push- ing forward SAR satellite constellation construction of disaster monitoring and warning field in China.%合成孔径雷达SAR(SyntheticApertureRadar)技术是一种主动的对地观测技术,已在国内外减灾领域得到了广泛的应用。环境减灾HJ-1CSAR卫星是我国第一颗民用SAR卫星,也是我国第一颗用于减灾救灾领域的SAR卫星,已于2012年11月19日发射成功。在HJ-1CSAR卫星发射前,从SAR技术特点出发,分别分析了单极化、多极化、干涉、极化干涉SAR数据在灾害预警监测评估领域的应用现状及潜力。对于推动利用SAR技术进行灾害监测预警业务体系向更深层面发展,推动高级空间技术在减灾领域的应用,以及推动我国在灾害监测预警领域的SAR卫星星座的建设具有重要意义。

  13. Feature Extraction and Classification of Oil Spills in SAR Imagery

    Directory of Open Access Journals (Sweden)

    Radhika V

    2011-09-01

    Full Text Available Synthetic Aperture RADAR (SAR imaging system is used to monitor the marine system. Oil spill pollution plays a significant role in damaging marine ecosystem. One main advantages of SAR is that it can generate imagery under all weather conditions. In a SAR image dark spots can be generated by number of phenomena. The dark spots may be of algae, low wind areas, coastal areas and oil spills. The detected dark spots are then classified based on the features. The features of dark spot are extracted to discriminate oil spill from look-alikes. The textural and statistical features are extracted and analyzed for oil spill identification. This paper discusses about the different feature extraction and classification method for oil spill detection and their preliminary results.

  14. Concealed target detection using augmented reality with SIRE radar

    Science.gov (United States)

    Saponaro, Philip; Kambhamettu, Chandra; Ranney, Kenneth; Sullivan, Anders

    2013-05-01

    The Synchronous Impulse Reconstruction (SIRE) forward-looking radar, developed by the U.S. Army Research Laboratory (ARL), can detect concealed targets using ultra-wideband synthetic aperture technology. The SIRE radar has been mounted on a Ford Expedition and combined with other sensors, including a pan/tilt/zoom camera, to test its capabilities of concealed target detection in a realistic environment. Augmented Reality (AR) can be used to combine the SIRE radar image with the live camera stream into one view, which provides the user with information that is quicker to assess and easier to understand than each separated. In this paper we present an AR system which utilizes a global positioning system (GPS) and inertial measurement unit (IMU) to overlay a SIRE radar image onto a live video stream. We describe a method for transforming 3D world points in the UTM coordinate system onto the video stream by calibrating for the intrinsic parameters of the camera. This calibration is performed offline to save computation time and achieve real time performance. Since the intrinsic parameters are affected by the zoom of the camera, we calibrate at eleven different zooms and interpolate. We show the results of a real time transformation of the SAR imagery onto the video stream. Finally, we quantify both the 2D error and 3D residue associated with our transformation and show that the amount of error is reasonable for our application.

  15. Flood occurrence mapping of the middle Mahakam lowland area using satellite radar

    Directory of Open Access Journals (Sweden)

    H. Hidayat

    2012-07-01

    Full Text Available Floodplain lakes and peatlands in the middle Mahakam lowland area are considered as ecologically important wetland in East Kalimantan, Indonesia. However, due to a lack of data, the hydrological functioning of the region is still poorly understood. Among remote sensing techniques that can increase data availability, radar is well-suitable for the identification, mapping, and measurement of tropical wetlands, for its cloud unimpeded sensing and night and day operation. Here we aim to extract flood extent and flood occurrence information from a series of radar images of the middle Mahakam lowland area. We explore the use of Phased Array L-band Synthetic Aperture Radar (PALSAR imagery for observing flood inundation dynamics by incorporating field water level measurements. Water level measurements were carried out along the river, in lakes and in peatlands, using pressure transducers. For validation of the open water flood occurrence map, bathymetry measurements were carried out in the main lakes. A series of PALSAR images covering the middle and lower Mahakam area in the years 2007 through 2010 were collected. A fully inundated region can be easily recognized on radar images from a dark signature. Open water flood occurrence was mapped using a threshold value taken from radar backscatter of the permanently inundated river and lakes areas. Radar backscatter intensity analysis of the vegetated floodplain area revealed consistently high backscatter values, indicating flood inundation under forest canopy. We used those values as the threshold for flood occurrence mapping in the vegetated area.

  16. 一种分布式小卫星SAR单视复图像信号仿真方法%Quick method of distributed small satellite synthetic aperture radar single-look complex image simulation

    Institute of Scientific and Technical Information of China (English)

    徐华平; 陈杰; 王宝发; 周荫清

    2006-01-01

    总结了分布式小卫星合成孔径雷达(DSS-SAR,Distributed Small Satellite Synthetic Aperture Radar)回波信号仿真所需具备的基本功能.给出了DSS-SAR的空间几何模型和信号模型.空间几何模型由描述小卫星编队构形的Hill方程给出,信号模型由单视复图像信号模型、信号相关性模型和干涉相位的统计特性共同描述.结合空间几何模型和单视复图像信号模型,提出了一种简洁的DSS-SAR单视复图像信号的仿真方法.该仿真方法中,小卫星的空间位置是根据虚拟中心空间位置和小卫星的编队构形计算得到,因此仿真时能够任意设置小卫星群的编队构形.通过对圆锥三维地形和平地两种地面场景的进行回波信号仿真,结果表明该仿真方法不但能够实现DSS-SAR信号仿真必须具备的功能,而且还具有实现简洁、误差加入方便等优点.

  17. Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2016-08-01

    Full Text Available In this paper, a semi-empirical algorithm for significant wave height (Hs and mean wave period (Tmw retrieval from C-band VV-polarization Sentinel-1 synthetic aperture radar (SAR imagery is presented. We develop a semi-empirical function for Hs retrieval, which describes the relation between Hs and cutoff wavelength, radar incidence angle, and wave propagation direction relative to radar look direction. Additionally, Tmw can be also calculated through Hs and cutoff wavelength by using another empirical function. We collected 106 C-band stripmap mode Sentinel-1 SAR images in VV-polarization and wave measurements from in situ buoys. There are a total of 150 matchup points. We used 93 matchups to tune the coefficients of the semi-empirical algorithm and the rest 57 matchups for validation. The comparison shows a 0.69 m root mean square error (RMSE of Hs with a 18.6% of scatter index (SI and 1.98 s RMSE of Tmw with a 24.8% of SI. Results indicate that the algorithm is suitable for wave parameters retrieval from Sentinel-1 SAR data.

  18. Foliage penetration radar detection and characterization of objects under trees

    CERN Document Server

    Davis, Mark

    2011-01-01

    This book covers all aspects of foliage penetration (FOPEN) radar, concentrating on both airborne military radar systems as well as earth resource mapping radars. It is the first concise and thorough treatment of FOPEN, covering the results of a decade-long investment by DARPA in characterizing foliage and earth surface with ultrawideband UHF and VHF synthetic aperture radar (SAR).

  19. GOTCHA experience report: three-dimensional SAR imaging with complete circular apertures

    Science.gov (United States)

    Ertin, Emre; Austin, Christian D.; Sharma, Samir; Moses, Randolph L.; Potter, Lee C.

    2007-04-01

    We study circular synthetic aperture radar (CSAR) systems collecting radar backscatter measurements over a complete circular aperture of 360 degrees. This study is motivated by the GOTCHA CSAR data collection experiment conducted by the Air Force Research Laboratory (AFRL). Circular SAR provides wide-angle information about the anisotropic reflectivity of the scattering centers in the scene, and also provides three dimensional information about the location of the scattering centers due to a non planar collection geometry. Three dimensional imaging results with single pass circular SAR data reveals that the 3D resolution of the system is poor due to the limited persistence of the reflectors in the scene. We present results on polarimetric processing of CSAR data and illustrate reasoning of three dimensional shape from multi-view layover using prior information about target scattering mechanisms. Next, we discuss processing of multipass (CSAR) data and present volumetric imaging results with IFSAR and three dimensional backprojection techniques on the GOTCHA data set. We observe that the volumetric imaging with GOTCHA data is degraded by aliasing and high sidelobes due to nonlinear flightpaths and sparse and unequal sampling in elevation. We conclude with a model based technique that resolves target features and enhances the volumetric imagery by extrapolating the phase history data using the estimated model.

  20. Imagerie Radar 3D en onde millimétrique pour la détection et la lecture des capteurs passifs et sans puce

    OpenAIRE

    Henry, Dominique; Aubert, Hervé; Pons, Patrick

    2015-01-01

    Cette communication traite de la détection et de la lecture à distance de capteurs passifs à l'aide d'un système radar FMCW millimétrique. Avec une résolution en profondeur de quelques centimètres et une résolution angulaire de l'ordre du degré, il est possible de localiser et d'interroger des capteurs démunis de batterie en réalisant une cartographie des échos radar en azimut, élévation et profondeur issus des modes de diffusion de structure et d'antenne des capteurs.

  1. Pathfinder radar development at Sandia National Laboratories

    Science.gov (United States)

    Castillo, Steven

    2016-05-01

    Since the invention of Synthetic Aperture Radar imaging in the 1950's, users or potential users have sought to exploit SAR imagery for a variety of applications including the earth sciences and defense. At Sandia Laboratories, SAR Research and Development and associated defense applications grew out of the nuclear weapons program in the 1980's and over the years has become a highly viable ISR sensor for a variety of tactical applications. Sandia SAR systems excel where real-­-time, high-­-resolution, all-­-weather, day or night surveillance is required for developing situational awareness. This presentation will discuss the various aspects of Sandia's airborne ISR capability with respect to issues related to current operational success as well as the future direction of the capability as Sandia seeks to improve the SAR capability it delivers into multiple mission scenarios. Issues discussed include fundamental radar capabilities, advanced exploitation techniques and human-­-computer interface (HMI) challenges that are part of the advances required to maintain Sandia's ability to continue to support ever changing and demanding mission challenges.

  2. Determination of the significant wave height from shadowing in synthetic radar images

    NARCIS (Netherlands)

    Wijaya, A.P.; Groesen, van E.

    2016-01-01

    Radar imagery is nowadays used to observe ocean waves despite the fact that radar images contain invisible areas because of the shadowing effect in the radar mechanism. Moreover, the radar images show the radar intensity which is not directly related to the wave height. This paper deals with the sub

  3. Commercial requirements for synthetic aperture radar

    Science.gov (United States)

    Lodge, Dale W. S.; Williamson, H. Dawn; Whitelaw, Alan S.; Howes, Sally; Keyte, Gordon E.

    1994-12-01

    Structured interviews were used to gather information on the commercial requirements and value of SAR data from about 2005 for the global sample of market sectors using cartographic information and spatial statistics. The results show the relative importance of major application areas as commercial prospects. The annual market projection for the period around 2005 using as yet an incomplete global sample is for over 20,000 scenes with a value of the order of $75 million. The most significant markets are expected to be for topographic maps, oceans and ice and agriculture. However, SAR is unlikely to be the sole source of information for any application but will be incorporated with other data as available. The results of the interviews have been used to define customer requirements on the ground segment, which showed that commercial partnership in the mission operations was essential. A hierarchial market model was developed to support the sampling strategy and to relate customer requirements to the SAR design. The work has established a baseline of information on which to plan a commercial SAR mission in the next century.

  4. Interferometric Synthetic Aperture Radar (IFSAR) Alaska

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS) National Geospatial Program (NGP) developed the Alaska Mapping Initiative (AMI) to collaborate with the State and other Federal...

  5. Monitoring and Risk Analysis of Land Subsidence in Beijing Based on Interferometric Synthetic Aperture Radar(InSAR) Technique%基于InSAR技术北京地区地面沉降监测与风险分析

    Institute of Scientific and Technical Information of China (English)

    陈蓓蓓; 宫辉力; 李小娟; 张有全; 党亚南; 宋柳霖

    2011-01-01

    以北京市典型地面沉降区为研究区,采用永久散射体技术--StamPS算法,利用覆盖北京地区的16幅ASAR图像进行永久散射体干涉处理,获得该区地面沉降监测信息,初步揭示了研究区地面沉降的空间分布特征.在此基础上,结合GIS空间分析方法,对地面沉降的风险范围、风险程度等进行综合分析,表明北京地区的地面沉降防治刻不容缓.%Land subsidence in Beijing has been an ongoing problem for the past four decades (since the later 1970s) ,which is induced by over-pumping groundwater continuously, becoming a negative effect on the sustainable economic development in plain areas. In this paper,Permanent Scatterers Interferometric Synthetic Aperture Radar( PS-InSAR) technique is used to detect and measure ground movement in this area(2003-2006). The detail information of deformation shows that spatial extent of subsidence is controlled by geologic structures ( Huangzhuang-Gaoliying and Nankou-Sunhe faults). In consideration of a series damages by land subsidence,risk assessment and zoning are very important for risk management. Based on the land subsidence retrieved by PSInSAR techniques using ASAR data, combining with the present situation of groundwater overexploitation and the thickness of compressive layer, a hazard assessment model of land subsidence in Beijing is established using the HP-Fuzzy method,the AHP-Fuzzy assessment model is analyzed by using a GIS-based modeling approach. Then,a case study is carried out in Miyun-Huairou-Shunyiarea of Beijing. As a result,the risk index of each study area is extracted by means of the AHP-Fuzzy method. Then the risk level of land subsidence is analyzed using the dimensional analytical method. It indicates that the risk of land subsidence in Beijing is indispensable. This result is reasonable and useful for land subsidence disaster prevention and reduction.

  6. 雷达干涉测量中人工角反射器设计及在影像图中的识别%Disign of the Arctificial Corner Reflector in Interferometric Synthetic Aperture Radar and Recognition in Images

    Institute of Scientific and Technical Information of China (English)

    黄洁慧; 谢谟文; 马睿; 何兴东; 李鹏飞

    2011-01-01

    合成孔径雷达干涉测量(InSAR)是20世纪后期发展起来的一种新的测量技术,具有全天时、全天候、能获得面数据等对地观测特点.但在实际应用中却受到时间和空间失相关以及大气效应等条件的制约.选取金沙江流域地处高山峡谷区的某河段为研究区域.由于传统的InSAR技术达不到理想监测效果,因此应用了角反射器(CR)技术.首先阐述了CR在InSAR技术不同发展阶段中的应用;介绍了其制作及现场安装过程中应注意的问题.最后采用双重阈值法来识别CR,识别出的CR位置与实测CR中心位置坐标相吻合,证明了其识别CR的有效性.%InSAR( Synthetic Aperture Radar Interferometry) is a new measuring technology which developed in late 20th century. It has the advantage of detecting earth surface in all weather conditions, in all time, and obtaining area data. But the practical application of InSAR technology is effected by loss of time-spatial relevance and atmospheric effect. One reach of Jinsha river valley was selected as the study area. The region is located in the mountain valley areas, the traditional InSAR technology can not achieve effective monitoring result, therefore corner reflector (CR) was deployed in the study area. First, the application of CR in different developmental stages of InSAR technology was described, in addition the manufacture of CR and notable problems in setting up process were introduced. Finally using double threshold value method to identify CR, the position of I-dentified CR was consistent with coordinate of CR central point. That the dual threshold method was effective to identify the CR was proved.

  7. Coherent processing for ISAR imaging with sparse apertures

    Institute of Scientific and Technical Information of China (English)

    SHENG JiaLian; ZHANG Lei; XU Gang; XING MengDao; BAO Zheng

    2012-01-01

    To implement target detection,tracking and imaging in a multifunctional radar system,the wideband measurements for inverse synthetic aperture radar (ISAR) imaging are usually sparsely recorded.Considering the incoherence problem in such sparse-aperture ISAR (SA-ISAR) systems,we concentrate on the study of a coherent processing method in this work.Based on an all-pole model,the incoherence parameters between abutting sub-apertures can be effectively estimated.After coherence compensation,an optimization-based SA-ISAR imaging approach is provided from the view of statistics.Simulation and real data experiments validate the feasibility and effectiveness of the proposals.

  8. Automated rectification and geocoding of SAR imagery

    Science.gov (United States)

    Kwok, R.; Curlander, J. C.

    1987-01-01

    An automated post-processing system has been developed for rectification and geocoding of SAR (Synthetic Aperture Radar) imagery. The system uses as input a raw uncorrected image from the operational SAR correlator, and produces as a standard output a rectified and geocoded product. The accurate geolocation of SAR image pixels is provided by a spatial transformation model which maps the slant range-azimuth SAR image pixels into their location on a prespecified map grid. This model predicts the geodetic location of each pixel by utilizing: the sensor platform position; a geoid model; the parameters of the data collection system and the processing parameters used in the SAR correlator. Based on their geodetic locations, the pixels are mapped by using the desired cartographic projection equations. This rectification and geocoding technique has been tested with Seasat and SIR-B images. The test results demonstrate absolute location uncertainty of less than 50 m and relative distortion (scale factor and skew) of less than 0.1 percent relative to local variations from the assumed geoid.

  9. Spaceborne radar applications in geology. An introduction to imaging radar and application examples of ERS SAR in geology and geomorphology

    Science.gov (United States)

    Fletcher, Karen

    2005-12-01

    This document is intended for geologists who are interested in broadening their knowledge of interpretation of imaging radar data, but also addresses the general public for reference and information. It introduces imaging radar as it may be used by technicians and image interpreters, stressing the use of synthetic aperture radar (SAR) for Earth observation in general and for geology in particular. Interferometric SAR is briefly treated, with some basic and practical hints. An illustrated application study on land subsidence is included. SAR/optical data fusion is explained, with examples of the different methods suggested. The main part of the document, part II, consists of 14 case studies that demonstrate the potential of SAR imagery for geology. These studies cover themes such as the detection and mapping of neotectonic activity, tectonic mapping, and recognition of karst structures, as well as analysis of active lahars and other volcanic events. They look into drainage systems in desert areas, consider lithofacies changes and morphostructure texture analysis, and they demonstrate the geological mapping of active tectonic compression. Finally, the document mentions the key points of the ESA SAR missions. Contacts for further information are also provided.

  10. Synthetic aperture integration (SAI) algorithm for SAR imaging

    Science.gov (United States)

    Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

    2013-07-09

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  11. Application of ground-penetrating radar imagery for three-dimensional visualisation of near-surface structures in ice-rich permafrost, Barrow, Alaska

    Science.gov (United States)

    Munroe, J.S.; Doolittle, J.A.; Kanevskiy, M.Z.; Hinkel, Kenneth M.; Nelson, F.E.; Jones, Benjamin M.; Shur, Y.; Kimble, J.M.

    2007-01-01

    Three-dimensional ground-penetrating radar (3D GPR) was used to investigate the subsurface structure of ice-wedge polygons and other features of the frozen active layer and near-surface permafrost near Barrow, Alaska. Surveys were conducted at three sites located on landscapes of different geomorphic age. At each site, sediment cores were collected and characterised to aid interpretation of GPR data. At two sites, 3D GPR was able to delineate subsurface ice-wedge networks with high fidelity. Three-dimensional GPR data also revealed a fundamental difference in ice-wedge morphology between these two sites that is consistent with differences in landscape age. At a third site, the combination of two-dimensional and 3D GPR revealed the location of an active frost boil with ataxitic cryostructure. When supplemented by analysis of soil cores, 3D GPR offers considerable potential for imaging, interpreting and 3D mapping of near-surface soil and ice structures in permafrost environments.

  12. Radar image San Francisco Bay Area, California

    Science.gov (United States)

    2000-01-01

    preliminary nature of this image product. These artifacts will be removed after further data processing.This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian Space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.Size: 38 km (24 miles) by 71 km (44 miles) Location: 37.7 deg. North lat., 122.2 deg. West lon. Orientation: North to the upper right Original Data Resolution: 30 meters (99 feet) Date Acquired: February 16, 2000

  13. Monitoring and characterizing natural hazards with satellite InSAR imagery

    Science.gov (United States)

    Lu, Zhong; Zhang, Jixian; Zhang, Yonghong; Dzurisin, Daniel

    2007-01-01

    Interferometric synthetic aperture radar (InSAR) provides an all-weather imaging capability for measuring ground-surface deformation and inferring changes in land surface characteristics. InSAR enables scientists to monitor and characterize hazards posed by volcanic, seismic, and hydrogeologic processes, by landslides and wildfires, and by human activities such as mining and fluid extraction or injection. Measuring how a volcano’s surface deforms before, during, and after eruptions provides essential information about magma dynamics and a basis for mitigating volcanic hazards. Measuring spatial and temporal patterns of surface deformation in seismically active regions is extraordinarily useful for understanding rupture dynamics and estimating seismic risks. Measuring how landslides develop and activate is a prerequisite to minimizing associated hazards. Mapping surface subsidence or uplift related to extraction or injection of fluids during exploitation of groundwater aquifers or petroleum reservoirs provides fundamental data on aquifer or reservoir properties and improves our ability to mitigate undesired consequences. Monitoring dynamic water-level changes in wetlands improves hydrological modeling predictions and the assessment of future flood impacts. In addition, InSAR imagery can provide near-real-time estimates of fire scar extents and fire severity for wildfire management and control. All-weather satellite radar imagery is critical for studying various natural processes and is playing an increasingly important role in understanding and forecasting natural hazards.

  14. Radar image registration and rectification

    Science.gov (United States)

    Naraghi, M.; Stromberg, W. D.

    1983-01-01

    Two techniques for radar image registration and rectification are presented. In the registration method, a general 2-D polynomial transform is defined to accomplish the geometric mapping from one image into the other. The degree and coefficients of the polynomial are obtained using an a priori found tiepoint data set. In the second part of the paper, a rectification procedure is developed that models the distortion present in the radar image in terms of the radar sensor's platform parameters and the topographic variations of the imaged scene. This model, the ephemeris data and the digital topographic data are then used in rectifying the radar image. The two techniques are then used in registering and rectifying two examples of radar imagery. Each method is discussed as to its benefits, shortcomings and registration accuracy.

  15. Quantifying sub-pixel urban impervious surface through fusion of optical and inSAR imagery

    Science.gov (United States)

    Yang, L.; Jiang, L.; Lin, H.; Liao, M.

    2009-01-01

    In this study, we explored the potential to improve urban impervious surface modeling and mapping with the synergistic use of optical and Interferometric Synthetic Aperture Radar (InSAR) imagery. We used a Classification and Regression Tree (CART)-based approach to test the feasibility and accuracy of quantifying Impervious Surface Percentage (ISP) using four spectral bands of SPOT 5 high-resolution geometric (HRG) imagery and three parameters derived from the European Remote Sensing (ERS)-2 Single Look Complex (SLC) SAR image pair. Validated by an independent ISP reference dataset derived from the 33 cm-resolution digital aerial photographs, results show that the addition of InSAR data reduced the ISP modeling error rate from 15.5% to 12.9% and increased the correlation coefficient from 0.71 to 0.77. Spatially, the improvement is especially noted in areas of vacant land and bare ground, which were incorrectly mapped as urban impervious surfaces when using the optical remote sensing data. In addition, the accuracy of ISP prediction using InSAR images alone is only marginally less than that obtained by using SPOT imagery. The finding indicates the potential of using InSAR data for frequent monitoring of urban settings located in cloud-prone areas. Copyright ?? 2009 by Bellwether Publishing, Ltd. All right reserved.

  16. 基于二次虚拟孔径扩展的双基地MIMO雷达相干分布式目标中心角度估计%Central Angle Estimation of Coherently Distributed Sources for Bistatic MIMO Radar Based on Second Virtual Array Aperture Extension

    Institute of Scientific and Technical Information of China (English)

    徐旭宇; 李小波; 梁浩; 牛朝阳; 董杰

    2014-01-01

    A new central angle estimation method of the coherently distributed sources for bistatic MIMO radar is proposed based on second virtual array aperture extension. Firstly, the bistatic MIMO radar data model for the coherently distributed sources with the identical deterministic angular distribution function and distribution parameter is built based on nonuniform array. The second virtual array aperture extension is also realized by the colocated difference arrays of the minimum redundancy arrays. Furthermore, the new correlation matrix is obtained via transformal, eliminating redundant and changeable dimensional matrix. Finally, the central angles of DODs and DOAs are estimated without pairing algorithm by the idea of ESPRIT. Because of the second virtual array aperture extension, the proposed method provides much more parameter identifiability and better parameter estimation performance than the conventional bistatic MIMO radar. The effectiveness of the proposed method is verified with the computer simulation.%该文提出了基于二次虚拟孔径扩展的双基地MIMO雷达相干分布式目标中心角度估计算法。首先构造了基于非均匀阵列的具有相同确定性角信号分布函数和分布参数的相干分布式目标的双基地MIMO雷达信号模型,再利用基于最小冗余的差分共置阵列思想,实现了阵元二次虚拟扩展;然后通过构造置换、去冗余和换维矩阵,得到了新的协方差矩阵;最后利用 ESPRIT 算法思想,估计出相干分布式目标的发射、接收中心角,并且实现了角度参数的自动配对。由于该文算法实现了阵元二次虚拟扩展,因此相比于传统MIMO雷达能识别更多的目标,具有更高的估计精度。实验仿真结果证明了该文算法的有效性。

  17. Shadow Probability of Detection and False Alarm for Median-Filtered SAR Imagery

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Analysis and Applications Dept.; Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Mission Engineering Dept.; Miller, John A. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems; Bishop, Edward E. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems; Horndt, Volker [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems

    2014-06-01

    Median filtering reduces speckle in synthetic aperture radar (SAR) imagery while preserving edges, at the expense of coarsening the resolution, by replacing the center pixel of a sliding window by the median value. For shadow detection, this approach helps distinguish shadows from clutter more easily, while preserving shadow shape delineations. However, the nonlinear operation alters the shadow and clutter distributions and statistics, which must be taken into consideration when computing probability of detection and false alarm metrics. Depending on system parameters, median filtering can improve probability of detection and false alarm by orders of magnitude. Herein, we examine shadow probability of detection and false alarm in a homogeneous, ideal clutter background after median filter post-processing. Some comments on multi-look processing effects with and without median filtering are also made.

  18. Oceanic pycnocline depth retrieval from SAR imagery in the existence of solitary internal waves

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar (SAR) images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD (conductivity-temperature-depth) data.

  19. Shallow Water Height Mapping With Interferometric Synthetic Aperture Sonar

    OpenAIRE

    Sergio Rui Silva; Sergio Cunha; Anibal Matos; Nuno Cruz

    2008-01-01

    Height mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance or natural resource monitoring. The use of an autonomous boat presents several advantages that case the use of synthetic aperture images to create three-dimensional topographic maps through interferometric techniques. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate imagery and bathymetry...

  20. Aperture optical antennas

    CERN Document Server

    Wenger, Jerome

    2014-01-01

    This contribution reviews the studies on subwavelength aperture antennas in the optical regime, paying attention to both the fundamental investigations and the applications. Section 2 reports on the enhancement of light-matter interaction using three main types of aperture antennas: single subwavelength aperture, single aperture surrounded by shallow surface corrugations, and subwavelength aperture arrays. A large fraction of nanoaperture applications is devoted to the field of biophotonics to improve molecular sensing, which are reviewed in Section 3. Lastly, the applications towards nano-optics (sources, detectors and filters) are discussed in Section 4.

  1. Perspective View, Radar Image, Color as Height, Molokai, Lanai and Maui, Hawaii

    Science.gov (United States)

    2000-01-01

    This perspective view shows three Hawaiian islands: Molokai (lower left), Lanai (right), and the northwest tip of Maui (upper left). Data such as these will be useful for studying the history of volcanic activity on these now extinct volcanoes. SRTM data also will help local officials evaluate and mitigate natural hazards for islands throughout the Pacific. For example, improved elevation data will make it easier for communities to plan for tsunamis (tidal waves generated by earthquakes around the perimeter of the Pacific) by helping them identify evacuation routes and areas prone to flooding.This perspective view combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Colors range from blue at the lowest elevations to white at the highest elevations. This image contains 1800 meters (5900 feet) of total relief.The Shuttle Radar Topography Mission (SRTM), launched on February 11,2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German (DLR) and Italian (ASI) space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.Size: 60 by 70 kilometers (37 by 43 miles) Location: 20.8 deg. North lat., 156.7 deg. West lon. Orientation: Looking southeast Original Data Resolution: 30 meters (99 feet) Date Acquired

  2. Model Order Selection in Multi-baseline Interferometric Radar Systems

    Directory of Open Access Journals (Sweden)

    Fulvio Gini

    2005-12-01

    Full Text Available Synthetic aperture radar interferometry (InSAR is a powerful technique to derive three-dimensional terrain images. Interest is growing in exploiting the advanced multi-baseline mode of InSAR to solve layover effects from complex orography, which generate reception of unexpected multicomponent signals that degrade imagery of both terrain radar reflectivity and height. This work addresses a few problems related to the implementation into interferometric processing of nonlinear algorithms for estimating the number of signal components, including a system trade-off analysis. Performance of various eigenvalues-based information-theoretic criteria (ITC algorithms is numerically investigated under some realistic conditions. In particular, speckle effects from surface and volume scattering are taken into account as multiplicative noise in the signal model. Robustness to leakage of signal power into the noise eigenvalues and operation with a small number of looks are investigated. The issue of baseline optimization for detection is also addressed. The use of diagonally loaded ITC methods is then proposed as a tool for robust operation in the presence of speckle decorrelation. Finally, case studies of a nonuniform array are studied and recommendations for a proper combination of ITC methods and system configuration are given.

  3. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  4. Flexible T/R Modules for Large-Aperture, Space-Based SAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SI2 Technologies, Inc (SI2) proposes to develop membrane compatible transmit/receive (T/R) modules for flexible, space-deployable synthetic aperture radar (SAR)...

  5. Étude et réalisation d'un système d'imagerie SAR exploitant des signaux et configurations de communication numérique

    OpenAIRE

    Riché, Vishal,

    2013-01-01

    Les travaux présentés dans cette thèse portent sur l'étude et la réalisation d'un système d'imagerie SAR (synthetic aperture radar) exploitant deux techniques provenant des communications numériques: la configuration MIMO et les signaux OFDM. Dans la première partie de cette étude, différentes méthodes de focalisation des signaux reçus pour la configuration MIMO sont proposées afin de mesurer l'impact de la configuration MIMO sur la robustesse du système d'imagerie SAR par rapport aux bruits....

  6. Parametric Sparse Representation and Its Applications to Radar Sensing

    Directory of Open Access Journals (Sweden)

    Li Gang

    2016-02-01

    Full Text Available Sparse signal processing has been utilized to the area of radar sensing. Due to the presence of unknown factors such as the motion of the targets of interest and the error of the radar trajectory, a predesigned dictionary cannot provide the optimally spare representation of the actual radar signals. This paper will introduce a method called parametric sparse representation, which is a special case of dictionary learning and can dynamically learn the unknown factors during the radar sensing and achieve the optimally sparse representation of radar signals. This paper will also introduce the applications of parametric sparse representation to Inverse Synthetic Aperture Radar imaging (ISAR imaging, Synthetic Aperture Radar imaging (SAR autofocusing and target recognition based on micro-Doppler effect.

  7. Radar Chart

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Radar Chart collection is an archived product of summarized radar data. The geographic coverage is the 48 contiguous states of the United States. These hourly...

  8. Priori knowledge based a bathymetry assessment method using the sun glitter imagery:a case study of sand waves on the Taiwan Banks

    Institute of Scientific and Technical Information of China (English)

    SHAO Hao; LI Yan; LI Li

    2014-01-01

    High resolution optical satellite imageries containing the sun glitter, similar to synthetic aperture radar (SAR) imageries, are useful in identifying and mapping of bottom topography in shallow waters. The errors in the previous studies are corrected, and a method for mapping submarine bottom topography is devel-oped using the sun glitter satellite imagery. The method is established on the basis of empirical description of a sand wave using an equation with two unknowns named r and k . In order to determine r and k , a“trial and error”approach is introduced and testified by a case study on the Taiwan Banks using an ASTER imagery. The results show that the inversed water depths match well with the sounding water depths. The a-greement between the inversed results and the in situ measurements is about 78%by comparing 371 points. Moreover, this method has the advantage in keeping the original appearance of a sand wave, especially in positions around the sand wave crest. The fine agreement indicates that the imaging model is flexible and the approach developed is feasible.

  9. EcoSAR: NASA's P-band fully polarimetric single pass interferometric airborne radar

    Science.gov (United States)

    Osmanoglu, B.; Rincon, R. F.; Fatoyinbo, T. E.; Lee, S. K.; Sun, G.; Daniyan, O.; Harcum, M. E.

    2014-12-01

    EcoSAR is a new airborne synthetic aperture radar imaging system, developed at the NASA Goddard Space Flight Center. It is a P-band sensor that employs a non-conventional and innovative design. The EcoSAR system was designed as a multi-disciplinary instrument to image the 3-dimensional surface of the earth from a single pass platform with two antennas. EcoSAR's principal mission is to penetrate the forest canopy to return vital information about the canopy structure and estimate biomass. With a maximum bandwidth of 200 MHz in H and 120 MHz in V polarizations it can provide sub-meter resolution imagery of the study area. EcoSAR's dual antenna, 32 transmit and receive channel architecture provides a test-bed for developing new algorithms in InSAR data processing such as single pass interferometry, full polarimetry, post-processing synthesis of multiple beams, simultaneous measurement over both sides of the flight track, selectable resolution and variable incidence angle. The flexible architecture of EcoSAR will create new opportunities in radar remote sensing of forest biomass, permafrost active layer thickness, and topography mapping. EcoSAR's first test flight occurred between March 27th and April 1st, 2014 over the Andros Island in Bahamas and Corcovado and La Selva National Parks in Costa Rica. The 32 channel radar system collected about 6 TB of radar data in about 12 hours of data collection. Due to the existence of radio and TV communications in the operational frequency band, acquired data contains strong radar frequency interference, which had to be removed prior to beamforming and focusing. Precise locations of the antennas are tracked using high-rate GPS and inertial navigation units, which provide necessary information for accurate processing of the imagery. In this presentation we will present preliminary imagery collected during the test campaign, show examples of simultaneous dual track imaging, as well as a single pass interferogram. The

  10. Subsurface Feature Mapping of Mars using a High Resolution Ground Penetrating Radar System

    Science.gov (United States)

    Wu, T. S.; Persaud, D. M.; Preudhomme, M. A.; Jurg, M.; Smith, M. K.; Buckley, H.; Tarnas, J.; Chalumeau, C.; Lombard-Poirot, N.; Mann, B.

    2015-12-01

    As the closest Earth-like, potentially life-sustaining planet in the solar system, Mars' future of human exploration is more a question of timing than possibility. The Martian surface remains hostile, but its subsurface geology holds promise for present or ancient astrobiology and future habitation, specifically lava tube (pyroduct) systems, whose presence has been confirmed by HiRISE imagery.The location and characterization of these systems could provide a basis for understanding the evolution of the red planet and long-term shelters for future manned missions on Mars. To detect and analyze the subsurface geology of terrestrial bodies from orbit, a novel compact (smallsat-scale) and cost-effective approach called the High-resolution Orbiter for Mapping gEology by Radar (HOMER) has been proposed. Adapting interferometry techniques with synthetic aperture radar (SAR) to a ground penetrating radar system, a small satellite constellation is able to achieve a theoretical resolution of 50m from low-Mars orbit (LMO). Alongside this initial prototype design of HOMER, proposed data processing methodology and software and a Mars mission design are presented. This project was developed as part of the 2015 NASA Ames Academy for Space Exploration.

  11. Radargrammetric Digital Surface Models Generation from Terrasar-X Imagery: Case Studies, Problems and Potentialities

    Science.gov (United States)

    Capaldo, P.; Crespi, M.; Fratarcangeli, F.; Nascetti, A.; Pieralice, F.

    2012-07-01

    The interest for the radargrammetric approach to Digital Surface Models (DSMs) generation has been growing in last years thanks to the availability of very high resolution imagery acquired by new SAR (Synthetic Aperture Radar) sensors, as COSMO-SkyMed, Radarsat-2 and TerraSAR-X, which are able to supply imagery up to 1 m ground resolution. DSMs radargrammetric generation approach consists of two basic steps, as for the standard photogrammetry applied to optical imagery: the imagery (at least a stereo pair) orientation and the image matching for the generation of the points cloud. The steps of the radargrammetric DSMs generation have been implemented into SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at Geodesy and Geomatics Institute of the University of Rome "La Sapienza". Moreover, starting from the radargrammetric orientation model, a tool for the Rational Polynomial Coefficients (RPCs) for SAR images have been implemented. The possibility to generate RPCs, re-parametrizing a rigorous orientation model through a standardized set of coefficients which can be managed by a Rational Polynomial Coefficients (RPFs) model (similarly to optical high resolution imagery) sounds of particular interest since, at present, the most part of SAR imagery (except from Radarsat-2) is not supplied with RPCs, although the corresponding RPFs model is available in several commercial software. In particular the RPCs model has been used in the matching process and in the stereo restitution for the DSMs generation, with the advantage of shorter computational time. This paper discusses the application and the results of the implemented algorithm for radargrammetric DSMs generation from TerraSAR-X SpotLight imagery, acquired in Spotlight mode over Trento (Northern Italy). Urban and extra-urban (forested, cultivated) areas were considered in two different tiles, and a final overall accuracy ranging from 4.5 to 6 meters was achieved as regards

  12. Joint UK/US Radar Program progress reports for period December 1--31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Rino, C.; Chambers, D.H.; Robey, H.F.; Belyea, J.

    1995-01-23

    Topics discussed in this report are current accomplishments in many functions to include: airborne RAR/SAR, radar data processor, ground based SAR signal processing workstation, static airborne radar, multi-aperture space-time array radar, radar field experiments, data analysis and detection theory, management, radar data analysis, modeling and analysis, current meter array, UCSB wave tank, stratified flow facility, Russian Institute of Applied Physics, and budget status.

  13. Increasing the sensitivity of controlled-source electromagnetics with synthetic aperture

    NARCIS (Netherlands)

    Fan, Y.; Snieder, R.; Slob, E.C.; Hunziker, J.W.; Singer, J.; Sheiman, J.; Rosenquist, M.

    2012-01-01

    Controlled-source electromagnetics (CSEM) has been used as a derisking tool in the hydrocarbon exploration industry. We apply the concept of synthetic aperture to the lowfrequency electromagnetic field in CSEM. Synthetic aperture sources have been used in radar imaging for many years. Using the synt

  14. Progress in dual-band dual-polarization shared-aperture SAR antennas

    Institute of Scientific and Technical Information of China (English)

    Shunshi ZHONG; Zhu SUN; Xiaorong TANG

    2009-01-01

    The progress in dual-band dual-polarization (DBDP) shared-aperture antennas for the synthetic aper-ture radar (SAR) application in the last decade is reviewed.Several designs of DBDP SAR antenna arrays are introduced with their main performances, then their comparison is summarized. In addition, some techniques enhancing DBDP antenna performances are presented.

  15. Compressive sensing for urban radar

    CERN Document Server

    Amin, Moeness

    2014-01-01

    With the emergence of compressive sensing and sparse signal reconstruction, approaches to urban radar have shifted toward relaxed constraints on signal sampling schemes in time and space, and to effectively address logistic difficulties in data acquisition. Traditionally, these challenges have hindered high resolution imaging by restricting both bandwidth and aperture, and by imposing uniformity and bounds on sampling rates.Compressive Sensing for Urban Radar is the first book to focus on a hybrid of two key areas: compressive sensing and urban sensing. It explains how reliable imaging, tracki

  16. Synthetic aperture ultrasound Fourier beamformation using virtual sources

    DEFF Research Database (Denmark)

    Moghimirad, Elahe; Villagómez Hoyos, Carlos Armando; Mahloojifar, Ali;

    2016-01-01

    An efficient Fourier beamformation algorithm is presented for multistatic synthetic aperture ultrasound imaging using virtual sources (FBV). The concept is based on the frequency domain wavenumber algorithm from radar and sonar and is extended to a multi-element transmit/receive configuration using...

  17. Fourier beamformation of multistatic synthetic aperture ultrasound imaging

    DEFF Research Database (Denmark)

    Moghimirad, Elahe; Villagómez Hoyos, Carlos Armando; Mahloojifar, Ali;

    2015-01-01

    A new Fourier beamformation (FB) algorithm is presented for multistatic synthetic aperture ultrasound imaging. It can reduce the number of computations by a factor of 20 compared to conventional Delay-and-Sum (DAS) beamformers. The concept is based on the wavenumber algorithm from radar and sonar...

  18. Variable-aperture screen

    Science.gov (United States)

    Savage, George M.

    1991-01-01

    Apparatus for separating material into first and second portions according to size including a plurality of shafts, a plurality of spaced disks radiating outwardly from each of the shafts to define apertures and linkage interconnecting the shafts for moving the shafts toward or away from one another to vary the size of the apertures while the apparatus is performing the separating function.

  19. Mastering Apple Aperture

    CERN Document Server

    Fitzgerald, Thomas

    2013-01-01

    Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

  20. Rotating Aperture System

    Science.gov (United States)

    Rusnak, Brian; Hall, James M.; Shen, Stewart; Wood, Richard L.

    2005-01-18

    A rotating aperture system includes a low-pressure vacuum pumping stage with apertures for passage of a deuterium beam. A stator assembly includes holes for passage of the beam. The rotor assembly includes a shaft connected to a deuterium gas cell or a crossflow venturi that has a single aperture on each side that together align with holes every rotation. The rotating apertures are synchronized with the firing of the deuterium beam such that the beam fires through a clear aperture and passes into the Xe gas beam stop. Portions of the rotor are lapped into the stator to improve the sealing surfaces, to prevent rapid escape of the deuterium gas from the gas cell.