WorldWideScience

Sample records for satellite synthetic aperture

  1. Monitoring coastal inundation with Synthetic Aperture Radar satellite data

    Science.gov (United States)

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

    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.

  2. CLPX-Satellite: Radarsat Synthetic Aperture Radar Imagery

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of time-series spaceborne Synthetic Aperture Radar (SAR) imagery of the three Cold Land Processes Field Experiment (CLPX) Meso-cell Study...

  3. 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

    of 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...

  4. Satellite synthetic aperture radar for monitoring of surface deformation in shallow underground mining environments

    CSIR Research Space (South Africa)

    Engelbrecht, J

    2016-08-01

    Full Text Available of using dInSAR is that large areas can be monitored in a single footprint. Satellites also orbit the meaning that frequent measurements can be made. Since measurements are made remotely, dInSAR effectively overcomes the limitations imposed by field... interferogram and associated deformation map over an area undergoing mining- induced subsidence Satellite synthetic aperture radar for monitoring of surface deformation in shallow underground mining environments Engelbrecht, J.1, and Inggs, M.R2 1...

  5. Means to achieve wide swath widths in synthetic aperture satellite borne radars

    Science.gov (United States)

    Cutrona, L. J.

    1978-01-01

    The radar range equation including processing gains for pulse compression and synthetic aperture generation was the starting point. System geometry considerations were introduced. For simplicity, flat earth geometry was used, although it was realized that this was not a good model for satellite-borne radars. Next, the constraints were introduced. These included those needed to avoid ambiguities in both range and azimuth, those needed to acheive the desired resolution, and those needed to achieve the desired swath width.

  6. NOAA high resolution sea surface winds data from Synthetic Aperture Radar (SAR) on the Sentinel-1 satellites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of high resolution sea surface winds data produced from Synthetic Aperture Radar (SAR) on board Sentinel-1A and Sentinel-1B satellites. This...

  7. 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...... effects, gap flow, coastal barrier jets, and atmospheric gravity waves are not only observed in SAR, but are also modeled well from HARMONIE. Offshore meteorological observations are not available, but wind speed and wind direction measurements from coastal meteorological masts are found to compare well...

  8. Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2008-01-01

    A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective is to im...

  9. A comparison of synthetic aperture radars applied for satellite remote sensing of the ocean surface

    Digital Repository Service at National Institute of Oceanography (India)

    Tilley, D.G.; Sarma, Y.V.B.

    Doppler imaging radars have orbited the earth aboard several spacecraft for the purpose of monitoring the ocean. Oceanographic applications of synthetic aperture radar (SAR) include measuring ocean wave fields, monitoring current fronts and sensing...

  10. 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.

  11. FLIGHT DEVELOPMENT OF A DISTRIBUTED INERTIAL SATELLITE MICRONAVIGATTION SYSTEM FOR SYNTHETIC - APERTURE RADAR

    Directory of Open Access Journals (Sweden)

    Alexander Vladimirovich Chernodarov

    2017-01-01

    Full Text Available The current state of the onboard systems is characterized by the integration of aviation and radio-electronic equipment systems for solving problems of navigation and control. These problems include micro-navigation of the anten- na phase center (APC of the radar during the review of the Earth's surface from aboard the aircraft. Increasing of the reso- lution of the radar station (RLS by hardware increasing the antenna size is not always possible due to restrictions on the aircraft onboard equipment weight and dimensions. Therefore the implementation of analytic extension of the radiation pattern by "gluing" the images, obtained by RLS on the aircraft motion trajectory is embodied. The estimations are con- verted into amendments to the signals of RLS with synthetic aperture RSA to compensate instabilities. The purpose of the research is building a theoretical basis and a practical implementation of procedures for evaluating the trajectory APS in- stabilities using a distributed system of inertial-satellite micro-navigation (DSMN taking into account the RSA flight oper- ations actual conditions. The technology of evaluation and compensation of RSA trajectory instabilities via DSMN is con- sidered. The implementation of this technology is based on the mutual support of inertial, satellite and radar systems. Syn- chronization procedures of inertial and satellite measurements in the evaluation of DSMN errors are proposed. The given results of DSMN flight testing justify the possibility and expediency to apply the proposed technology in order to improve the resolution of RSA. The compensation of aircraft trajectory instabilities in RSA signals can be provided by inertial- satellite micro-navigation system, taking into account the actual conditions of the RSA flight operations. The researches show that in order to achieve the required resolution of RSA it seems to be appropriate to define the rational balance be- tween accuracy DSMN characteristics

  12. Transionospheric synthetic aperture imaging

    CERN Document Server

    Gilman, Mikhail; Tsynkov, Semyon

    2017-01-01

    This landmark monograph presents the most recent mathematical developments in the analysis of ionospheric distortions of SAR images and offers innovative new strategies for their mitigation. As a prerequisite to addressing these topics, the book also discusses the radar ambiguity theory as it applies to synthetic aperture imaging and the propagation of radio waves through the ionospheric plasma, including the anisotropic and turbulent cases. In addition, it covers a host of related subjects, such as the mathematical modeling of extended radar targets (as opposed to point-wise targets) and the scattering of radio waves off those targets, as well as the theoretical analysis of the start-stop approximation, which is used routinely in SAR signal processing but often without proper justification. The mathematics in this volume is clean and rigorous – no assumptions are hidden or ambiguously stated. The resulting work is truly interdisciplinary, providing both a comprehensive and thorough exposition of the field,...

  13. Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Gammelmark, Kim Løkke

    2006-01-01

    The paper describes the use of synthetic aperture (SA) imaging in medical ultrasound. SA imaging is a radical break with today's commercial systems, where the image is acquired sequentially one image line at a time. This puts a strict limit on the frame rate and the possibility of acquiring...... of SA imaging. Due to the complete data set, it is possible to have both dynamic transmit and receive focusing to improve contrast and resolution. It is also possible to improve penetration depth by employing codes during ultrasound transmission. Data sets for vector flow imaging can be acquired using...... short imaging sequences, whereby both the correct velocity magnitude and angle can be estimated. A number of examples of both phantom and in-vivo SA images will be presented measured by the experimental ultrasound scanner RASMUS to demonstrate the many benefits of SA imaging....

  14. 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...

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

    Science.gov (United States)

    Ramsey, Elijah W.; 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).

  16. Synthetic Aperture Ladar (SAL): Fundamental Theory, Design Equations for a Satellite System, and Laboratory Demonstration

    National Research Council Canada - National Science Library

    Lucke, Robert

    2002-01-01

    .... Design equations are presented to allow quick assessment of the hardware parameters required for a notional system, most notably optical aperture sizes and the laser's power, chirp, and pulse rate capabilities...

  17. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB....... The first part of the scientific contribution investigates an implementation of pulse inversion for THI on the experimental ultrasound system SARUS. The technique is initially implemented for linear array transducers and then expanded for convex array transducers. The technique is evaluated based on spatial...

  18. Compounding in synthetic aperture imaging

    DEFF Research Database (Denmark)

    Hansen, J. M.; Jensen, J. A.

    2012-01-01

    A method for obtaining compound images using synthetic aperture data is investigated using a convex array transducer. The new approach allows spatial compounding to be performed for any number of angles without reducing the frame rate or temporal resolution. This important feature is an intrinsic...... property of how the compound images are constructed using synthetic aperture data and an improvement compared with how spatial compounding is obtained using conventional methods. The synthetic aperture compound images are created by exploiting the linearity of delay-and-sum beamformation for data collected...... from multiple spherical emissions to synthesize multiple transmit and receive apertures, corresponding to imaging the tissue from multiple directions. The many images are added incoherently, to produce a single compound image. Using a 192-element, 3.5-MHz, λ-pitch transducer, it is demonstrated from...

  19. Imaging with Synthetic Aperture Radar

    CERN Document Server

    Massonnet, Didier

    2008-01-01

    Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

  20. Monitoring of Arctic Conditions from a Virtual Constellation of Synthetic Aperture Radar Satellites

    Science.gov (United States)

    2013-09-30

    of glaciers and the speed of motion. h) Monitoring of the Northwest Passage. APPROACH 2013 MIZ Pilot Program: Starting in June to end of...September 2013, CSTARS provided satellite data collections for three different efforts during the Marginal Ice Zone (MIZ): 1) Large-Scale Evolution ...should occur. Large Scale Evolution of the MIZ Large-scale images were used to monitor the Central Beaufort Gyre along 150 W and following the ice

  1. Optimizing Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Spatial compound images are constructed from synthetic aperture data acquired using a linear phased-array transducer. Compound images of wires, tissue, and cysts are created using a method, which allows both transmit and receive compounding without any loss in temporal resolution. Similarly...... to conventional imaging, the speckle reduction achieved by spatial compounding comes at the cost of a reduced detail resolution and a compromise must be made. Using a performance indicator, which can be measured from an image of a phantom without cysts, it is demonstrated how a compromise can be made, which...... is optimal for lesion detection. Synthetic aperture data are acquired from unfocused emissions and 154 compound images are constructed by synthesizing different aperture configurations with more or less compounding, all maintaining a constant resolution across depth corresponding to an f-number of 2...

  2. 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.

  3. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando

    The main objective of this project was to continue the development of a synthetic aperture vector flow estimator. This type of estimator is capable of overcoming two of the major limitations in conventional ultrasound systems: 1) the inability to scan large region of interest with high temporal r...

  4. Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation

    Science.gov (United States)

    Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.

    2005-01-01

    We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

  5. 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.

  6. Synthetic aperture ladar concept for infrastructure monitoring

    Science.gov (United States)

    Turbide, Simon; Marchese, Linda; Terroux, Marc; Bergeron, Alain

    2014-10-01

    Long range surveillance of infrastructure is a critical need in numerous security applications, both civilian and military. Synthetic aperture radar (SAR) continues to provide high resolution radar images in all weather conditions from remote distances. As well, Interferometric SAR (InSAR) and Differential Interferometric SAR (D-InSAR) have become powerful tools adding high resolution elevation and change detection measurements. State of the art SAR systems based on dual-use satellites are capable of providing ground resolutions of one meter; while their airborne counterparts obtain resolutions of 10 cm. D-InSAR products based on these systems could produce cm-scale vertical resolution image products. Deformation monitoring of railways, roads, buildings, cellular antennas, power structures (i.e., power lines, wind turbines, dams, or nuclear plants) would benefit from improved resolution, both in the ground plane and vertical direction. The ultimate limitation to the achievable resolution of any imaging system is its wavelength. State-of-the art SAR systems are approaching this limit. The natural extension to improve resolution is to thus decrease the wavelength, i.e. design a synthetic aperture system in a different wavelength regime. One such system offering the potential for vastly improved resolution is Synthetic Aperture Ladar (SAL). This system operates at infrared wavelengths, ten thousand times smaller than radar wavelengths. This paper presents a laboratory demonstration of a scaled-down infrastructure deformation monitoring with an Interferometric Synthetic Aperture Ladar (IFSAL) system operating at 1.5 μm. Results show sub-millimeter precision on the deformation applied to the target.

  7. Wind energy applications of synthetic aperture radar

    DEFF Research Database (Denmark)

    Badger, Merete

    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...... stability, and the fraction of turbines operating. Wind farm wake effects are detected up to 20 kmdownwind 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...

  8. A practical algorithm for the retrieval of floe size distribution of Arctic sea ice from high-resolution satellite Synthetic Aperture Radar imagery

    Directory of Open Access Journals (Sweden)

    Byongjun Hwang

    2017-07-01

    Full Text Available In this study, we present an algorithm for summer sea ice conditions that semi-automatically produces the floe size distribution of Arctic sea ice from high-resolution satellite Synthetic Aperture Radar data. Currently, floe size distribution data from satellite images are very rare in the literature, mainly due to the lack of a reliable algorithm to produce such data. Here, we developed the algorithm by combining various image analysis methods, including Kernel Graph Cuts, distance transformation and watershed transformation, and a rule-based boundary revalidation. The developed algorithm has been validated against the ground truth that was extracted manually with the aid of 1-m resolution visible satellite data. Comprehensive validation analysis has shown both perspectives and limitations. The algorithm tends to fail to detect small floes (mostly less than 100 m in mean caliper diameter compared to ground truth, which is mainly due to limitations in water-ice segmentation. Some variability in the power law exponent of floe size distribution is observed due to the effects of control parameters in the process of de-noising, Kernel Graph Cuts segmentation, thresholds for boundary revalidation and image resolution. Nonetheless, the algorithm, for floes larger than 100 m, has shown a reasonable agreement with ground truth under various selections of these control parameters. Considering that the coverage and spatial resolution of satellite Synthetic Aperture Radar data have increased significantly in recent years, the developed algorithm opens a new possibility to produce large volumes of floe size distribution data, which is essential for improving our understanding and prediction of the Arctic sea ice cover

  9. 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...

  10. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels

    2008-01-01

    Current ultrasonic blood flow velocity measurement systems are subject to a number of limitations, including limited frame rate, aliasing artifacts, and that only the velocity component along the ultrasound beam is estimated. This dissertation aims at solving some of these problems. The main part...... of the thesis considers a method for estimating the two-dimensional velocity vector within the image plane. This method, called synthetic aperture vector flow imaging, is first shortly reviewed. The main contribution of this work is partly an analysis of the method with respect to focusing effects, motion...... estimation. The method can be used for increasing the frame rate of color flow maps or alternatively for a new imaging modality entitled quadroplex imaging, featuring a color flow map and two independent spectrograms at a high frame rate. The second is an alternative method for ultrasonic vector velocity...

  11. Detection of urban environments using advanced land observing satellite phased array type L-band synthetic aperture radar data through different classification techniques

    Science.gov (United States)

    Pradhan, Biswajeet; Abdullahi, Saleh; Seddighi, Younes

    2016-07-01

    Urban environments are very dynamic phenomena, and it is essential to update urban-related information for various applications. In this regard, remotely sensed data have been utilized widely to extract and monitor urban land use and land cover changes. Particularly, synthetic aperture radar (SAR) data, due to several advantages of this technology in comparison to passive sensors, provides better performance especially in tropical regions. However, the methodological approaches for extraction of information from SAR images are another important task that needs to be considered appropriately. This paper attempts to investigate and compare the performance of different image classification techniques for extracting urban areas using advanced land observing satellite phased array type L-band synthetic aperture radar imagery. Several object- [such as rule based (RB), support vector machine (SVM) and K-nearest neighbor (K-NN)] and pixel-based [decision tree (DT)] classification techniques were implemented, and their results were compared in detail. The overall results indicated RB classification performed better than other techniques. Furthermore, DT method, due to its predefined rules, distinguished the land cover classes better than SVM and K-NN, which were based on training datasets. Nevertheless, this study confirms the potential of SAR data and object-based classification techniques in urban detection and land cover mapping.

  12. Practical Applications of Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav Ivanov; Kortbek, Jacob; Jensen, Jørgen Arendt

    2010-01-01

    Synthetic aperture imaging has been a focus of research for almost 3 decades. The research carried out at the Center for Fast Ultrasound Imaging has demonstrated that synthetic aperture focusing not only can be used in-vivo, but that it also yields superior B-mode and blood flow images. In the last...... years synthetic aperture focusing has moved from the lab to commercial products. The implementations vary in their scope and purpose. Some scanners use synthetic aperture imaging to improve the detail and contrast resolution of the system. Others to increase the image uniformity. Yet others use......, and multiple angle flash imaging are just a few of the names used to describe the commercial implementations of synthetic aperture focusing. Although they sound like different algorithms, they are the same in their core, as revealed in this paper....

  13. GOLD MINERAL PROSPECTING USING PHASED ARRAY TYPE L-BAND SYNTHETIC APERTURE RADAR (PALSAR SATELLITE REMOTE SENSING DATA, CENTRAL GOLD BELT, MALAYSIA

    Directory of Open Access Journals (Sweden)

    A. Beiranvand Pour

    2016-06-01

    Full Text Available 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.

  14. 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.

  15. Aperture undersampling using compressive sensing for synthetic aperture stripmap imaging

    Science.gov (United States)

    Leier, Stefan; Zoubir, Abdelhak M.

    2014-12-01

    Synthetic aperture imaging is a high-resolution imaging technique employed in radar and sonar applications, which construct a large aperture by constantly transmitting pulses while moving along a scene of interest. In order to avoid azimuth image ambiguities, spatial sampling requirements have to be fulfilled along the aperture trajectory. The latter, however, limits the maximum speed and, therefore, the coverage rate of the imaging system. This paper addresses the emerging field of compressive sensing for stripmap synthetic aperture imaging using transceiver as well as single-transmitter and multi-receiver systems so as to overcome the spatial Nyquist criterion. As a consequence, future imaging systems will be able to significantly reduce their mission time due to an increase in coverage rate. We demonstrate the capability of our proposed compressive sensing approach to at least double the maximum sensor speed based on synthetic data and real data examples. Simultaneously, azimuth image ambiguities are successfully suppressed. The real acoustical measurements are obtained by a small-scale ultrasonic synthetic aperture laboratory system.

  16. Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar Level 1.0: 2006-2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Americas ALOS Data Node (AADN) With the Japan Aerospace Exploration Agency's (JAXA's) launch of the Advanced Land Observation Satellite (ALOS) in January 2006, a new...

  17. An Incomplete Inventory of Suspected Human-Induced Surface Deformation in North America Detected by Satellite Interferometric Synthetic-Aperture Radar

    Directory of Open Access Journals (Sweden)

    Alana G. Semple

    2017-12-01

    Full Text Available We used satellite interferometric synthetic-aperture radar (InSAR data to document ground deformation across North America suspected to be caused by human activities. We showed that anthropogenic deformation can be measured from space across the continent and thus satellite observations should be collected routinely to characterize this deformation. We included results from the literature as well as new analysis of more than 5000 interferograms from the European Remote Sensing (ERS satellite, Envisat, the Advanced Land Observing Satellite (ALOS, and other satellites, collectively spanning the period 1992–2015. This compilation, while not complete in terms of spatial or temporal coverage nor uniform in quality over the region, contains 263 different areas of likely anthropogenic ground deformation, including 65 that were previously unreported. The sources can be attributed to groundwater extraction (50%, geothermal sites (6%, hydrocarbon production (20%, mining (21%, and other sources (3% such as lake level changes driven by human activities and tunneling. In a few areas, the source of deformation is ambiguous. We found at least 80 global positioning system (GPS stations within 20 km of of these areas that could be contaminated by the anthropogenic deformation. At sites where we performed a full time series analysis, we found a mix of steady and time-variable deformation rates. For example, at the East Mesa Geothermal Field in California, we found an area that changed from subsidence to uplift around 2006, even though publicly available records of pumping and injection showed no change during that time. We illustrate selected non-detections from wastewater injection in Oklahoma and eastern Texas, where we found that the detection threshold with available data is >0.5 cm/yr. This places into doubt previous results claiming detection below this threshold in eastern Texas. However, we found likely injection-induced uplift in a different area of

  18. Compact X-band Synthetic Aperture Radar with Deployable Plane Antenna and RF Feeding System through Non-contact Waveguides - Project of a 100kg-class SAR Satellite

    OpenAIRE

    Saito, Hirobumi; Akbar, Prilando Rizki; Ravindra, Vinay; Tomiki, Atsushi; Watanabe, Hiromi; Hirokawa, Jiro; Zhang, Mia; Shirasaka, Seiko

    2016-01-01

    We are developing a small synthetic aperture radar (SAR) that is compatible with 100kg class satellite. A constellation of such small SAR satellites is promising for shot revisit time of earth observations. The SAR antenna is a deployable honeycomb panel antenna with slot array, that can be stowed compactly. RF instruments are on a satellite structure and RF signal is fed to a deployable antenna through a non-contact choke flange at a hinge. This small SAR project for a responsive observation...

  19. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    This Ph.D. project was carried out at the Center for Fast Ultrasound Imaging, Technical University of Denmark. The goal was to improve existing imaging techniques in order to make them suitable for real-time three-dimensional ultrasound scanning. This dissertation focuses on the synthetic aperture...... imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture...

  20. 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

  1. 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.

  2. 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

  3. Synthetic Aperture Imaging in Medical Ultrasound

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Gammelmark, Kim; Pedersen, Morten

    2004-01-01

    Synthetic Aperture (SA) ultrasound imaging is a relatively new and unexploited imaging technique. The images are perfectly focused both in transmit and receive, and have a better resolution and higher dynamic range than conventional ultrasound images. The blood flow can be estimated from SA image...

  4. Fast Parametric Beamformer for Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev

    2008-01-01

    This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3-D by their origin, direction...

  5. Parametric Beamformer for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2006-01-01

    In this paper a parametric beamformer, which can handle all imaging modalities including synthetic aperture imaging, is presented. The image lines and apodization coefficients are specified parametrically, and the lines can have arbitrary orientation and starting point in 3D coordinates...

  6. Synthetic Aperture Beamformation using the GPU

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Schaa, Dana; Jensen, Jørgen Arendt

    2011-01-01

    A synthetic aperture ultrasound beamformer is implemented for a GPU using the OpenCL framework. The implementation supports beamformation of either RF signals or complex baseband signals. Transmit and receive apodization can be either parametric or dynamic using a fixed F-number, a reference...

  7. Final Report: Detection and Characterization of Underground Facilities by Stochastic Inversion and Modeling of Data from the New Generation of Synthetic Aperture Satellites

    Energy Technology Data Exchange (ETDEWEB)

    Foxall, W; Cunningham, C; Mellors, R; Templeton, D; Dyer, K; White, J

    2012-02-27

    Many clandestine development and production activities can be conducted underground to evade surveillance. The purpose of the study reported here was to develop a technique to detect underground facilities by broad-area search and then to characterize the facilities by inversion of the collected data. This would enable constraints to be placed on the types of activities that would be feasible at each underground site, providing a basis the design of targeted surveillance and analysis for more complete characterization. Excavation of underground cavities causes deformation in the host material and overburden that produces displacements at the ground surface. Such displacements are often measurable by a variety of surveying or geodetic techniques. One measurement technique, Interferometric Synthetic Aperture Radar (InSAR), uses data from satellite-borne (or airborne) synthetic aperture radars (SARs) and so is ideal for detecting and measuring surface displacements in denied access regions. Depending on the radar frequency and the acquisition mode and the surface conditions, displacement maps derived from SAR interferograms can provide millimeter- to centimeter-level measurement accuracy on regional and local scales at spatial resolution of {approx}1-10 m. Relatively low-resolution ({approx}20 m, say) maps covering large regions can be used for broad-area detection, while finer resolutions ({approx}1 m) can be used to image details of displacement fields over targeted small areas. Surface displacements are generally expected to be largest during or a relatively short time after active excavation, but, depending on the material properties, measurable displacement may continue at a decreasing rate for a considerable time after completion. For a given excavated volume in a given geological setting, the amplitude of the surface displacements decreases as the depth of excavation increases, while the area of the discernable displacement pattern increases. Therefore, the

  8. Ships as salient objects in synthetic aperture radar imaginary

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2016-07-01

    Full Text Available The widespread access to Synthetic Aperture Radar data has created a need for more precise ship extraction, specifically in low-to-medium resolution imagery. While Synthetic Aperture Radar pixel resolution is improving for a large swaths...

  9. Introduction: The Alaska Synthetic Aperture Radar Facility special section

    Science.gov (United States)

    Carsey, Frank D.; McNutt, Lyn; Rothrock, D. Andrew

    1994-11-01

    In 1985 the National Aeronautics and Space Administration (NASA) and the University of Alaska agreed to implement, at the Geophysical Institute of the Fairbanks campus, a facility dedicated to the acquisition, processing, distribution, and archival of synthetic aperture radar (SAR) data to be downlinked from satellites. Since then, the Alaska SAR Facility (ASF) has been an active part of NASA's Mission to Planet Earth. ASF Program goals were outlined by Carsey et al. [1987]. Plans were put in place to support three satellites, and the first two, the First European Remote Sensing Satellite (ERS 1) (launched in My 1991) and the Japanese Earth Resources Satellite (JERS 1) (launched in February 1992) are presently in orbit and are being supported by ASF. The third, the Canadian RADARSAT, is scheduled for launch in the spring of 1995. Future satellite missions by U.S. or foreign agencies may well be added in time.

  10. Optimization of Synthetic Aperture Image Quality

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando

    2016-01-01

    resolution (CTR). The results of the study showed that SA imaging with only 32 emissions and maximum sweep angle of 22 degrees yields a very good image quality compared with using 256 emissions and the full aperture size. Therefore the number of emissions and the maximum sweep angle in the SA can......Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters...... effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generating high resolution SA images. Optimization of the image quality is mainly performed based on measures...

  11. 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

  12. Fast parametric beamformer for synthetic aperture imaging.

    Science.gov (United States)

    Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev

    2008-08-01

    This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3D by their origin, direction, and inter-sample distance. The delay calculation is recursive and inspired by the coordinate rotation digital computer (CORDIC) algorithm. Only 3 parameters per channel and line are needed for their generation. The calculation of apodization coefficients is based on a piece- wise linear approximation. The implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed after every emission. Summing all low-resolution images produces a perfectly focused high-resolution image. The design of the beamformer is modular, and a single beamformation unit can produce 4600 low-resolution images per second, each consisting of 32 lines and 1024 complex samples per line. In its present incarnation, 3 such modules fit in a single device. The summation of low-resolution images is performed internally in the FPGA to reduce the required bandwidth. The delays are calculated with a precision of 1/16th of a sample, and the apodization coefficients with 7-bit precision. The accumulation of low-resolution images is performed with 24-bit precision. The level of the side- and grating lobes, introduced by the use of integer numbers in the calculations and truncation of intermediate results, is below -86 dB from the peak.

  13. Synthetic aperture radar processing with tiered subapertures

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, A.W. [Sandia National Labs., Albuquerque, NM (United States). Synthetic Aperture Radar Dept.

    1994-06-01

    Synthetic Aperture Radar (SAR) is used to form images that are maps of radar reflectivity of some scene of interest, from range soundings taken over some spatial aperture. Additionally, the range soundings are typically synthesized from a sampled frequency aperture. Efficient processing of the collected data necessitates using efficient digital signal processing techniques such as vector multiplies and fast implementations of the Discrete Fourier Transform. Inherent in image formation algorithms that use these is a trade-off between the size of the scene that can be acceptably imaged, and the resolution with which the image can be made. These limits arise from migration errors and spatially variant phase errors, and different algorithms mitigate these to varying degrees. Two fairly successful algorithms for airborne SARs are Polar Format processing, and Overlapped Subaperture (OSA) processing. This report introduces and summarizes the analysis of generalized Tiered Subaperture (TSA) techniques that are a superset of both Polar Format processing and OSA processing. It is shown how tiers of subapertures in both azimuth and range can effectively mitigate both migration errors and spatially variant phase errors to allow virtually arbitrary scene sizes, even in a dynamic motion environment.

  14. Revolutionary astrophysics using an incoherent synthetic optical aperture

    Science.gov (United States)

    Rafanelli, Gerard L.; Cosner, Christopher M.; Spencer, Susan B.; Wolfe, Douglas; Newman, Arthur; Polidan, Ronald; Chakrabarti, Supriya

    2017-09-01

    We describe a paradigm shift for astronomical observatories that would replace circular apertures with rotating synthetic apertures. Rotating Synthetic Aperture (RSA) observatories can enable high value science measurements for the lowest mass to orbit, have superior performance relative to all sparse apertures, can provide resolution of 20m to 30m apertures having the collecting area of 8m to 12m telescopes with much less mass, risk, schedule, and cost. RSA is based on current, or near term technology and can be launched on a single, current launch vehicle to L2. Much larger apertures are possible using the NASA Space Launch System.

  15. Compound imaging using Synthetic Aperture Sequential Beamformation

    DEFF Research Database (Denmark)

    Jensen, Casper Bo; Jensen, Jonas; Hemmsen, Martin Christian

    2011-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is a technique with low complexity and the ability to yield a more uniform lateral resolution with range. However, the presence of speckle artifacts in ultrasound images degrades the contrast. In conventional imaging speckle is reduced by using...... spatial compounding at the cost of a reduced frame rate. The objective is to apply spatial compounding to SASB and evaluate if the images have a reduced speckle appearance and thereby an improved image quality in terms of contrast compared to ordinary SASB. Using the simulation software Field II, RF data...... detection the five second stage images are added to form the compounded image. Using a ProFocus scanner and the 8804 linear array transducer (BK Medical, Herlev, Denmark) measurements of a phantom containing water filled cysts are obtained to validate the simulation results. The setup is the same...

  16. A Method for Synthetic Aperture Compounding

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2010-01-01

    An approach to perform ultrasound spatial compounding using synthetic aperture data is proposed. The approach allows compounding to be performed for any number of directions without reducing the frame rate or temporal resolution. It is demonstrated how the contrast is improved by compounding...... of 5 mm and scattering levels ranging from -3 to -12 dB relative to the background are imaged at 2 depths. Compound images composed of 1-5 images with an angular separation of 2 degrees are constructed and for the cysts at -3, -6, -9, and -12 dB, a CNR of -0.43, -1.11, -1.44, and -1.91 dB are obtained...

  17. 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)

  18. SARUS: A Synthetic Aperture Real-Time Ultrasound System

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Holten-Lund, Hans; Nilsson, Ronnie Thorup

    2013-01-01

    The Synthetic Aperture Real-time Ultrasound System (SARUS) for acquiring and processing synthetic aperture (SA) data for research purposes is described. The specifications and design of the system are detailed, along with its performance for SA, nonlinear, and 3-D flow estimation imaging. SARUS a...

  19. Synthetic Aperture Sequential Beamformation applied to medical imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system ...

  20. Impact of element pitch on synthetic aperture ultrasound imaging

    NARCIS (Netherlands)

    Hasegawa, H.; Korte, C.L. de

    2016-01-01

    PURPOSE: Synthetic aperture imaging was introduced in medical ultrasound to obtain high-quality images. In synthetic aperture ultrasound imaging, spherical transmit waves illuminate a target region from different positions, resulting in low-resolution images for each transmission. By coherent

  1. Synthetic aperture lidar as a future tool for earth observation

    Science.gov (United States)

    Turbide, Simon; Marchese, Linda; Terroux, Marc; Bergeron, Alain

    2017-11-01

    Synthetic aperture radar (SAR) is a tool of prime importance for Earth observation; it provides day and night capabilities in various weather conditions. State-of-the-art satellite SAR systems are a few meters in height and width and achieve resolutions of less than 1 m with revisit times on the order of days. Today's Earth observation needs demand higher resolution imaging together with timelier data collection within a compact low power consumption payload. Such needs are seen in Earth Observation applications such as disaster management of earthquakes, landslides, forest fires, floods and others. In these applications the availability of timely reliable information is critical to assess the extent of the disaster and to rapidly and safely deploy rescue teams. Synthetic aperture lidar (SAL) is based on the same basic principles as SAR. Both rely on the acquisition of multiple electromagnetic echoes to emulate a large antenna aperture providing the ability to produce high resolution images. However, in SAL, much shorter optical wavelengths (1.5 μm) are used instead of radar ones (wavelengths around 3 cm). Resolution being related to the wavelength, multiple orders of magnitude of improvement could be theoretically expected. Also, the sources, the detector, and the components are much smaller in optical domain than those for radar. The resulting system can thus be made compact opening the door to deployment onboard small satellites, airborne platforms and unmanned air vehicles. This has a strong impact on the time required to develop, deploy and use a payload. Moreover, in combination with airborne deployment, revisit times can be made much smaller and accessibility to the information can become almost in real-time. Over the last decades, studies from different groups have been done to validate the feasibility of a SAL system for 2D imagery and more recently for 3D static target imagery. In this paper, an overview of the advantages of this emerging technology will

  2. 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.

  3. Calibration of the TUD Ku-band Synthetic Aperture Radiometer

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1995-01-01

    The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs......, followed by an image reconstruction based on an inverse Fourier transform, results in an imaging instrument without the need of mechanical scan. The thinned aperture and the non-scanning feature make the technique attractive for low frequency spaceborne radiometer systems, e.g. at L-band. Initial...

  4. In-vivo examples of synthetic aperture vector flow imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann

    2007-01-01

    are processed, and movies of full vector flow images are generated. This paper presents still frames from different time instances of these movies. The movie from the femoral data tracks the accelerating velocity in the femoral artery during systole and a backwards flow at the end of the systole. A complex flow...... would be needed. Synthetic aperture vector flow imaging could potentially provide this. The purpose of this paper is to test the synthetic aperture vector flow imaging method on challenging in-vivo data. Two synthetic aperture in-vivo data sets are acquired using a commercial linear array transducer...

  5. 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.

  6. CLPX-Airborne: Airborne Synthetic Aperture Radar (AIRSAR) Imagery

    Data.gov (United States)

    National Aeronautics and Space Administration — Airborne Synthetic Aperture Radar (AIRSAR) is a side-looking imaging radar that is able to collect data irrespective of daylight or cloud cover. The AIRSAR...

  7. 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...

  8. The development of deep learning in synthetic aperture radar imagery

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2017-05-01

    Full Text Available The usage of remote sensing to observe environments necessitates interdisciplinary approaches to derive effective, impactful research. One remote sensing technique, Synthetic Aperture Radar, has shown significant benefits over traditional remote...

  9. Retrieval of Wind Speed Using an L-band Synthetic Aperture Radar

    DEFF Research Database (Denmark)

    Monaldo, Frank M.; Thompson, Donald R.; Badger, Merete

    2007-01-01

    usefulness over the ocean. Most recent wind retrievals from spaceborne SARs have been at C-band for ERS-1/2, Radarsat, and Envisat. With the launch of the sophisticated multi- polarization Phased Array L-band Synthetic Aperture Radar (PALSAR) on the Advanced Land Observing Satellite (ALOS), we renew...

  10. Use of Synthetic Aperture Radar in Cold Climate Flood Response

    Science.gov (United States)

    Yarbrough, L. D.

    2009-12-01

    The purpose of this study was to investigate the usefulness of Synthetic Aperture Radar (SAR) satellite images during a cold climate disaster response event. There were 15 European Space Agency (ESA) Advanced Synthetic Aperture Radar ASAR scenes, five Japan Aerospace Exploration Agency (JAXA) Phased Array type L-band Synthetic Aperture Radar (PALSAR) scenes, one RADARSAT2 scene, and numerous optical sensor data. These data were primarily used to indentify floodwater inundation polygons and flow vectors. However, in cold climate flooding, there are complicating factors such as frazil ice, ice jams, and snow-covered, frozen flood waters that are not present during warmer flooding events. The imagery was obtained through the International Charter "Space and Major Disasters.” The Charter aims at providing a unified system of space data acquisition and delivery to those affected by natural or man-made disasters through Authorized Users. Each member agency has committed resources to support the provisions of the Charter, and thus is helping to mitigate the effects of disasters on human life and property. On 25 March 2009, the Charter was activated in response to the flooding along the Red River of the North in the states of North Dakota and Minnesota of the United States. The delivery time of a single SAR scene from a Charter participant was less than 12 hours from the time of acquisition. This expedited service allowed additional time for creating image-based derivations, field checking and delivery to a decision maker or emergency responder. SAR-derived data sets include identification of river ice and saturated ground conditions. This data could be provided to experts in river ice engineering for use in the development of plans to reduce ice jamming, its effect on water levels and additional stresses on river infrastructure. During disaster response applications, SAR data was found to very useful in indentifying open water and the front of ice jams. Using a river

  11. Early development in synthetic aperture lidar sensing and processing for on-demand high resolution imaging

    Science.gov (United States)

    Bergeron, Alain; Turbide, Simon; Terroux, Marc; Marchese, Linda; Harnisch, Bernd

    2017-11-01

    The quest for real-time high resolution is of prime importance for surveillance applications specially in disaster management and rescue mission. Synthetic aperture radar provides meter-range resolution images in all weather conditions. Often installed on satellites the revisit time can be too long to support real-time operations on the ground. Synthetic aperture lidar can be lightweight and offers centimeter-range resolution. Onboard airplane or unmanned air vehicle this technology would allow for timelier reconnaissance. INO has developed a synthetic aperture radar table prototype and further used a real-time optronic processor to fulfill image generation on-demand. The early positive results using both technologies are presented in this paper.

  12. 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

  13. Development Status of Compact X-band Synthetic Aperture Radar Compatible with a100kg-class SAR Satellite and Its Future Plan

    OpenAIRE

    Akbar, Prilando Rizki; Ravindra, Vinay; Watanabe, Hiromi; Pyne, Budhaditya; Tanaka, Kouji; Mita, Makoto; Hirokawa, Jiro; Ura, Kenji; Ijichi, Koichi; Saito, Hirobumi; Shirasaka, Seiko

    2017-01-01

    We have proposed a novel SAR system compatible with a 100kg-class small satellite. This SAR development is funded for four years (2016-2019) by Japanese government. At present we are developing engineering model (EM). This paper describes the EM test preliminary results and the future plan. The specifications of SAR observation are single polarization SAR with 1m ground resolution at minimum. A size of the satellite is 0.7m x 0.7m x 0.7m on a rocket. A size of the deployed antenna is 4.9m x 0...

  14. Application of Linear Prediction Technique to Passive Synthetic Aperture Processing

    Directory of Open Access Journals (Sweden)

    Hou Yunshan

    2010-01-01

    Full Text Available A method for the synthesis of an aperture with improved angular resolution and array gain is described. The proposed method explores the merit of linear prediction technique to improve the performance of conventional ETAM (extended towed array measurements method. Previous efforts to improve the ETAM method generally focused on how to get more accurate estimation of overlap correlator, with an aim to reduce bearing estimation variance. In this paper, however, we discuss how to further improve the angular resolution when the effective synthetic aperture is rather limited. We resort to linear prediction technique to further extend the synthetic aperture obtained by ETAM, which produces a much longer virtual aperture. Results from simulations and lake experiment showed that the proposed LP-ETAM method achieved better angular resolution than ETAM.

  15. Application of Linear Prediction Technique to Passive Synthetic Aperture Processing

    Science.gov (United States)

    Hou, Yunshan; Huang, Jianguo; Jiang, Min; Jin, Yong

    2010-12-01

    A method for the synthesis of an aperture with improved angular resolution and array gain is described. The proposed method explores the merit of linear prediction technique to improve the performance of conventional ETAM (extended towed array measurements) method. Previous efforts to improve the ETAM method generally focused on how to get more accurate estimation of overlap correlator, with an aim to reduce bearing estimation variance. In this paper, however, we discuss how to further improve the angular resolution when the effective synthetic aperture is rather limited. We resort to linear prediction technique to further extend the synthetic aperture obtained by ETAM, which produces a much longer virtual aperture. Results from simulations and lake experiment showed that the proposed LP-ETAM method achieved better angular resolution than ETAM.

  16. 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...

  17. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

    2013-01-01

    Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic ap...

  18. 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.

  19. Synthetic Aperture Sequential Beamforming implemented on multi-core platforms

    DEFF Research Database (Denmark)

    Kjeldsen, Thomas; Lassen, Lee; Hemmsen, Martin Christian

    2014-01-01

    This paper compares several computational ap- proaches to Synthetic Aperture Sequential Beamforming (SASB) targeting consumer level parallel processors such as multi-core CPUs and GPUs. The proposed implementations demonstrate that ultrasound imaging using SASB can be executed in real- time with ...

  20. Implementation of Synthetic Aperture Imaging in Medical Ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Kortbek, Jacob; Nikolov, Svetoslav

    2010-01-01

    The main advantage of medical ultrasound imaging is its real time capability, which makes it possible to visualize dynamic structures in the human body. Real time synthetic aperture imaging puts very high demands on the hardware, which currently cannot be met. A method for reducing the number of ...

  1. Real-time synthetic aperture imaging: opportunities and challenges

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2006-01-01

    Synthetic aperture (SA) ultrasound imaging has not been introduced in commercial scanners mainly due to the computational cost associated with the hardware implementation of this imaging modality. SA imaging redefines the term beamformed line. Since the acquired information comes from all points ...

  2. Motion compensated beamforming in synthetic aperture vector flow imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2006-01-01

    In synthetic aperture imaging the beamformed data from a number of emissions are summed to create dynamic focusing in transmit. This makes the method susceptible to motion, which is especially the case for the synthetic aperture flow estimation method, where large movements are expected. In this ......In synthetic aperture imaging the beamformed data from a number of emissions are summed to create dynamic focusing in transmit. This makes the method susceptible to motion, which is especially the case for the synthetic aperture flow estimation method, where large movements are expected....... In this paper, these motion effects are considered. A number of Field II simulations of a single scatterer moving at different velocities are performed both for axial and lateral velocities from 0 to 1 m/s. Data are simulated at a pulse repetition frequency of 5 kHz. The signal-to-noise ratio (SNR......) of the beamformed response from the scatterer at all velocities is compared to that of a stationary scatterer. For lateral movement, the SNR drops almost linearly with velocity to -4 dB at I m/s, while for axial movement the SNR drop is largest, when the scatterer moves a quarter of a wavelength between emissions...

  3. Synthetic Aperture Sequential Beamforming using Spatial Matched Filtering

    DEFF Research Database (Denmark)

    Schou, Mikkel; di Ianni, Tommaso; Bouzari, Hamed

    2017-01-01

    Synthetic Aperture Sequential Beamforming (SASB) has shown to achieve a good resolution and high penetration depth. The low complexity at the transducer level of the beamformer makes it ideal for use with a handheld device. SASB with a low F# (≤ 0.5) can achieve even better resolution at the cost...

  4. A Digital Data Processor for Synthetic Aperture Radar

    NARCIS (Netherlands)

    Vlothuizen, W.J.; Medenblik, H.J.W.

    2007-01-01

    This paper presents a Digital Data Processor (DDP) for Synthetic Aperture Radar (SAR). The DDP captures SAR data at a 1 GHz sample rate and processes data at 350 MB/s. Data reduction is performed by a digital down converter, programmable decimating filter and a fully programmable presummer. The

  5. 2-D Tissue Motion Compensation of Synthetic Transmit Aperture Images

    DEFF Research Database (Denmark)

    Gammelmark, Kim Løkke; Jensen, Jørgen Arendt

    2014-01-01

    Synthetic transmit aperture (STA) imaging is susceptible to tissue motion because it uses summation of low-resolution images to create the displayed high-resolution image. A method for 2-D tissue motion correction in STA imaging is presented. It utilizes the correlation between highresolution ima...

  6. 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...

  7. Duplex synthetic aperture imaging with tissue motion compensation

    DEFF Research Database (Denmark)

    Gammelmark, Kim; Jensen, Jørgen Arendt

    2003-01-01

    This paper investigates a method for tissue motion estimation and compensation in synthetic transmits aperture imaging. The approach finds the tissue velocity and the direction of the motion at very tissue region by cross-correlating high resolution lines beamformed along multiple directions at e...

  8. Transverse flow imaging using synthetic aperture directional beamforming

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav

    2002-01-01

    Current ultrasound scanners only determine the velocity along the ultrasound beam, since data is only focused along the emitted beam. Synthetic aperture ultrasound systems have the capability of focusing simultaneously in all directions. This is used here to focus along the flow direction and the...

  9. Velocity estimation using synthetic aperture imaging [blood flow

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a ful...

  10. Experimental Study of Convex Coded Synthetic Transmit Aperture Imaging

    DEFF Research Database (Denmark)

    Gammelmark, Kim; Jensen, Jørgen Arendt

    2002-01-01

    Synthetic transmit aperture imaging is investigated using a convex array transducer. To increase the signal-to-noise ratio, a multi-element subaperture is used to emulate the spherical wave transmission, and the conventional short excitation pulse is replaced by a linear FM signal. The approach i...

  11. In Vivo Evaluation of Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Peter Møller; Lange, Theis

    2012-01-01

    Ultrasound in vivo imaging using synthetic aperture sequential beamformation (SASB) is compared with conventional imaging in a double blinded study using side-by-side comparisons. The objective is to evaluate if the image quality in terms of penetration depth, spatial resolution, contrast...

  12. Adaptive Receive and Transmit Apodization for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Austeng, Andreas; Synnevåg, Johan-Fredrik

    2009-01-01

    This paper suggests a framework for utilizing adaptive, data-dependent apodization weights on both the receiving and transmitting aperture for Synthetic Aperture (SA) ultrasound imaging. The suggested approach is based on the Minimum Variance (MV) beamformer and consists of two steps. A set...... of uniquely designed receive apodization weights are applied to pre-summed element data forming a set of adaptively weighted images; these are in SA literature conventionally referred to as low-resolution images. The adaptive transmit apodization is obtained by applying MV across the full set of single...

  13. Multi element synthetic aperture transmission using a frequency division approach

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2003-01-01

    In synthetic aperture imaging an image is created by a number of single element defocused emissions. A low resolution image is created after every emission and a high resolution image is formed when the entire aperture has been covered. Since only one element is used at a time the energy....... The transmitting elements are excited so that N virtual sources are formed. All sources are excited using one subset at a time. The signals can be separated by matched filtration, and the corresponding information is extracted. The individual source information is hence available in every emission and the method...

  14. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    DEFF Research Database (Denmark)

    Chang, Rui; Zhu, Rong; Badger, Merete

    2014-01-01

    ENVISAT advanced SAR (ASAR) for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard......In view of the high cost and sparse spatial resolution of offshore meteorological observations, ocean winds retrieved from satellites are valuable in offshore wind resource assessment as a supplement to in situ measurements. This study examines satellite synthetic aperture radar (SAR) images from...

  15. Synthetic aperture flow imaging using dual stage beamforming

    DEFF Research Database (Denmark)

    Li, Ye; Jensen, Jørgen Arendt

    2013-01-01

    A method for synthetic aperture flow imaging using dual stage beamforming has been developed. The main motivation is to increase the frame rate and still maintain a beamforming quality sufficient for flow estimation that is possible to implement in a commercial scanner. This method can generate...... continuous high frame rate flow images with lower calculation demands than the full synthetic aperture flow imaging. The performance of the approach was investigated using Field II simulations and measurements with the experimental scanner SARUS. A laminar flow with a parabolic profile was generated...... of beamformed samples are reduced by a factor of 64 times, and the frame rate is much higher than the conventional method for the same velocity estimation accuracy....

  16. Synthetic Aperture Flow Imaging Using a Dual Beamformer Approach

    DEFF Research Database (Denmark)

    Li, Ye

    . However, while the conventional ultrasound imaging of making color flow mapping provides useful information in many circumstances, the spatial velocity resolution and frame rate are limited. The entire velocity distribution consists of image lines from different directions, and each image line...... is estimated using multiple emissions. Therefore, it is very difficult to acquire a full volume of data for the blood flow in the heart in real-time. A radical break with this has been the synthetic aperture technique. This technique makes it possible to increase the frame rate, and the reconstruction also...... makes it possible to improve significantly the focusing and frame rate. However, it requires a large amount of calculations to fulfill the performance because the signal from each channel is stored and processed simultaneously. The implementation of the full synthetic aperture would be very expensive...

  17. Performance of Synthetic Aperture Compounding for in-vivo imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2011-01-01

    A method for synthetic aperture compounding (SAC) is applied to data from water tank measurements, data from a tissue-mimicking phantom, and clinical data from the abdomen of a healthy 27 year old male. Further, using this method compounding can be obtained without any loss in temporal resolution....... The water tank measurements reveal an improved detail resolution of 45% when comparing SAC to conventional compounding and an improvement of 22%, when comparing to synthetic aperture (SA) imaging. The cystic resolution at 12 dB is improved by 50% and 12% when comparing SAC to conventional compounding and SA......, contrast ratios (CR) are computed between regions in the portal and hepatic veins and the surrounding tissue. An average improvement of 15% is obtained when comparing SAC images to SA images without compounding....

  18. Preliminary comparison of 3D synthetic aperture imaging with Explososcan

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Hansen, Jens Munk; Ferin, Guillaume

    2012-01-01

    phased array with a pitch of 300 μm, made by Vermon. For both imaging techniques, 289 emissions are used to image a volume spanning 60 in both the azimuth and elevation direction and 150mm in depth. This results for both techniques in a frame rate of 18 Hz. The implemented synthetic aperture technique...... by four and still, generally, improve the imaging quality....

  19. Implementation of real-time duplex synthetic aperture ultrasonography

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Larsen, Lee; Kjeldsen, Thomas

    2015-01-01

    This paper presents a real-time duplex synthetic aperture imaging system, implemented on a commercially available tablet. This includes real-time wireless reception of ultrasound signals and GPU processing for B-mode and Color Flow Imaging (CFM). The objective of the work is to investigate the im...... and that the required bandwidth between the probe and processing unit is within the current Wi-Fi standards....

  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. SARUS: A Synthetic Aperture Real-time Ultrasound System.

    Science.gov (United States)

    Jensen, Jørgen Arendt; Holten-Lund, Hans; Nilsson, Ronnie Thorup; Hansen, Martin; Larsen, Ulrik Darling; Domsten, Rune Petter; Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Nikolov, Svetoslav Ivanov; Pihl, Michael Johannes; Du, Yigang; Rasmussen, Joachim Hee; Rasmussen, Morten Fischer

    2013-09-01

    The Synthetic Aperture Real-time Ultrasound System (SARUS) for acquiring and processing synthetic aperture (SA) data for research purposes is described. The specifications and design of the system are detailed, along with its performance for SA, nonlinear, and 3-D flow estimation imaging. SARUS acquires individual channel data simultaneously for up to 1024 transducer elements for a couple of heart beats, and is capable of transmitting any kind of excitation. The 64 boards in the system house 16 transmit and 16 receive channels each, where sampled channel data can be stored in 2 GB of RAM and processed using five field-programmable gate arrays (FPGAs). The fully parametric focusing unit calculates delays and apodization values in real time in 3-D space and can produce 350 million complex samples per channel per second for full non-recursive synthetic aperture B-mode imaging at roughly 30 high-resolution images/s. Both RF element data and beamformed data can be stored in the system for later storage and processing. The stored data can be transferred in parallel using the system's sixty-four 1-Gbit Ethernet interfaces at a theoretical rate of 3.2 GB/s to a 144-core Linux cluster.

  2. An implementation of synthetic aperture focusing technique in frequency domain.

    Science.gov (United States)

    Stepinski, Tadeusz

    2007-07-01

    A new implementation of a synthetic aperture focusing technique (SAFT) based on concepts used in synthetic aperture radar and sonar is presented in the paper. The algorithm, based on the convolution model of the imaging system developed in frequency domain, accounts for the beam pattern of the finite-sized transducer used in the synthetic aperture. The 2D fast Fourier transform (FFT) is used for the calculation of a 2D spectrum of the ultrasonic data. The spectrum is then interpolated to convert the polar coordinate system used for the acquisition of ultrasonic signals to the rectangular coordinates used for the presentation of imaging results. After compensating the transducer lobe amplitude profile using a Wiener filter, the transformed spectrum is subjected to the 2D inverse Fourier transform to get the time-domain image again. The algorithm is computationally attractive due to the use of 2D FFT. The performance of the proposed frequency-domain algorithm and the classical time-domain SAFT are compared in the paper using simulated and real ultrasonic data.

  3. SOURCES OF ARTEFACTS IN SYNTHETIC APERTURE RADAR INTERFEROMETRY DATA SETS

    Directory of Open Access Journals (Sweden)

    K. Becek

    2012-07-01

    Full Text Available In recent years, much attention has been devoted to digital elevation models (DEMs produced using Synthetic Aperture Radar Interferometry (InSAR. This has been triggered by the relative novelty of the InSAR method and its world-famous product—the Shuttle Radar Topography Mission (SRTM DEM. However, much less attention, if at all, has been paid to sources of artefacts in SRTM. In this work, we focus not on the missing pixels (null pixels due to shadows or the layover effect, but rather on outliers that were undetected by the SRTM validation process. The aim of this study is to identify some of the causes of the elevation outliers in SRTM. Such knowledge may be helpful to mitigate similar problems in future InSAR DEMs, notably the ones currently being developed from data acquired by the TanDEM-X mission. We analysed many cross-sections derived from SRTM. These cross-sections were extracted over the elevation test areas, which are available from the Global Elevation Data Testing Facility (GEDTF whose database contains about 8,500 runways with known vertical profiles. Whenever a significant discrepancy between the known runway profile and the SRTM cross-section was detected, a visual interpretation of the high-resolution satellite image was carried out to identify the objects causing the irregularities. A distance and a bearing from the outlier to the object were recorded. Moreover, we considered the SRTM look direction parameter. A comprehensive analysis of the acquired data allows us to establish that large metallic structures, such as hangars or car parking lots, are causing the outliers. Water areas or plain wet terrains may also cause an InSAR outlier. The look direction and the depression angle of the InSAR system in relation to the suspected objects influence the magnitude of the outliers. We hope that these findings will be helpful in designing the error detection routines of future InSAR or, in fact, any microwave aerial- or space

  4. Multielement Synthetic Transmit Aperture Imaging Using Temporal Encoding

    DEFF Research Database (Denmark)

    Gammelmark, Kim; Jensen, Jørgen Arendt

    2003-01-01

    A new method to increase the signal-to-noise ratio (SNR) of synthetic transmit aperture imaging is investigated. The approach utilizes multiple elements to emulate a spherical wave, and the conventional short excitation pulse is replaced by a linear frequency-modulated (FM) signal. The approach...... is evaluated in terms of image quality parameters in comparison to linear array imaging. Field II simulations using an 8.5-MHz linear array transducer with 128 elements show an improvement in lateral resolution of up to 30% and up to 10.75% improvement in contrast resolution for the new approach. Measurements...

  5. Experimental investigation of synthetic aperture flow angle estimation

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2005-01-01

    -correlation as a function of velocity and angle. This paper presents an experimental investigation of this velocity angle estimation method based on a set of synthetic aperture flow data measured using our RASMUS experimental ultrasound system. The measurements are performed for flow angles of 60, 75, and 90 deg...... for the experiments, and the emitted pulse is a 20 micro sec. chirp, linearly sweeping frequencies from approximately 3.5 to 10.5 MHz. The flow angle could be estimated with an average bias up to 5.0 deg., and a average standard deviation between 0.2 deg. and 5.2 deg. Using the angle estimates, the velocity...

  6. Comparison between different encoding schemes for synthetic aperture imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2002-01-01

    Synthetic transmit aperture ultrasound (STAU) imaging can create images with as low as 2 emissions, making it attractive for 3D real-time imaging. Two are the major problems to be solved: (1) complexity of the hardware involved, and (2) poor image quality due to low signal to noise ratio (SNR). We...... have solved the first problem by building a scanner capable of acquiring data using STAU in real-time. The SNR is increased by using encoded signals, which make it possible to send more energy in the body, while reserving the spatial and contrast resolution. The performance of temporal, spatial...

  7. Beaconless search and rescue using polarimetric synthetic aperture radar

    Science.gov (United States)

    McCandless, Samuel W.; Huxtable, Barton D.; Mansfield, Arthur W.; Wallace, Ronald; Larsen, Rudolph; Rais, Houra

    1996-03-01

    In developing a beaconless search and rescue capability to quickly locate small aircraft that have crashed in remote areas, NASA's Search and Rescue (S&R) Program brings together advanced polarimetric synthetic aperture radar processing, field and laboratory tests, and state-of-the-art automated target detection algorithms. This paper provides the status of this program, which began with experiments conducted in concert with the JPL DC-8 AirSAR in 1989 at the Duke University Forest. The program is being conducted by NASA's Goddard Space Flight Center (GSFC) under the auspices of the Search and Rescue Office.

  8. Imaging blood’s velocity using synthetic aperture ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Li, Ye

    2012-01-01

    The blood velocity vector can be estimated using synthetic aperture techniques in medical ultrasound by using short emission sequences. The whole image region is insonified and the flow can be tracked in all directions continuously. This is a major advantage compared to commercial systems, since...... the separation between blood and tissue is greatly eased by this, and the estimates can be averaged over long time than in traditional systems. Vector velocity imaging can, thus, be made and attain an order of magnitude higher precision than in current commercial systems and at higher frame rates. It is also...... possible to visualize very slow moving flow. The paper will present methods for making such imaging....

  9. 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).

  10. Investigation of the feasability for 3D synthetic aperture imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2003-01-01

    This paper investigates the feasibility of implementing real-time synthetic aperture 3D imaging on the experimental system developed at the Center for Fast Ultrasound Imaging using a 2D transducer array. The target array is a fully populated 32 × 32 3 MHz array with a half wavelength pitch....... The elements of the array are grouped in blocks of 16 × 8, which can simultaneously be accessed by the 128 channels of the scanner. Using 8-to-1 high-voltage analog multiplexors, any group of 16 × 8 elements can be accessed. Simulations are done using Field II using parameters from a 32 x 32 elements...

  11. Sensitivity of synthetic aperture laser optical feedback imaging

    CERN Document Server

    Glastre, Wilfried; Jacquin, Olivier; Hugon, Olivier; De Chatellus, Hugues Guillet

    2012-01-01

    In this paper we compare the sensitivity of two imaging configurations both based on Laser Optical Feedback Imaging (LOFI). The first one is direct imaging, which uses conventional optical focalisation on target and the second one is made by Synthetic Aperture (SA) Laser, which uses numerical focalisation. We show that SA configuration allows to obtain good resolutions with high working distance and that the drawback of SA imagery is that it has a worse photometric balance in comparison to conventional microscope. This drawback is partially compensated by the important sensitivity of LOFI. Another interest of SA relies on the capacity of getting a 3D information in a single x-y scan.

  12. Multi-Element Synthetic Transmit Aperture Imaging using Temporal Encoding

    DEFF Research Database (Denmark)

    Gammelmark, Kim; Jensen, Jørgen Arendt

    2002-01-01

    show better performance for EMESTA imaging after the linear array focus. Both methods have similar contrast performance. Measurements areperformed using our experimental multi-channel ultrasound scanning system, RASMUS. The designed linear FM signal obtains temporal side lobes below -55 dB, and SNR......A new method to increase the signal-to-noise-ratio (SNR) of synthetic transmit aperture (STA) imaging is investigated. The new approach is called temporally Encoded Multi-Element STA imaging (EMESTA). It utilizes multiple elements to emulate a single transmit element, and the conventional short...

  13. CHARACTERISTICS OF AIRBORNE INTERFEROMETRIC SYNTHETIC APERTURE RADAR WITH SECTOR SCAN

    Directory of Open Access Journals (Sweden)

    Evgenii E. Nechayev

    2017-01-01

    Full Text Available One of the drawbacks of airborne interferometric synthetic aperture radar is a relatively narrow swath compared to analogous space based systems. Increasing the swath with side view of the interferometer can be possible by increasing the flight altitude and angle of sight. At the same time the height measurement accuracy decreases due to slant range distance increase. Another possible way of swath increasing is using sector scan. The efficiency of sector scan using in interferometric synthetic aperture radar is analyzed in this paper. The mathematical model and geometry of height measurement at a sector scan have been discussed. There was made an analysis of the effect of terrain height and observation angle on received signal phase changing. Observation angle changing is shown to contribute to the phase changing. Potential height accuracy measurement was calculated. The calculation results show that increasing the observation angle reduces height accuracy measurement. The maximum accuracy decrease is obtained at the observation angle of 90°. Despite height accuracy measurement decrease applying the sector scan allow to expand the swath. The accuracy decrease can be limited by selecting optimal parameters of scanning.

  14. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    Directory of Open Access Journals (Sweden)

    Stephen A. Boppart

    2008-06-01

    Full Text Available Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT, utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR. In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  15. Harmonic ultrasound imaging using synthetic aperture sequential beamforming

    DEFF Research Database (Denmark)

    2012-01-01

    A method includes generating an ultrasound image based on the harmonic components in the received echoes using multi-stage beam forming and data generated therefrom. An ultrasound imaging system (100, 200) includes a transducer array (108) including a plurality of transducer elements configured t....... The ultrasound imaging system further includes a synthetic aperture processor (128), including a second beam former (130) configured to process the stored intermediate scan lines, based on a synthetic aperture algorithm, generating a focused image.......A method includes generating an ultrasound image based on the harmonic components in the received echoes using multi-stage beam forming and data generated therefrom. An ultrasound imaging system (100, 200) includes a transducer array (108) including a plurality of transducer elements configured...... to emit ultrasound signals and receive echoes generated in response to the emitted ultrasound signals. The ultrasound imaging system further includes transmit circuitry (1 10) that generates a set of pulses that actuate a set of the plurality of transducer elements to emit ultrasound signals...

  16. Study of Wide Swath Synthetic Aperture Ladar Imaging Techology

    Directory of Open Access Journals (Sweden)

    Zhang Keshu

    2017-02-01

    Full Text Available Combining synthetic-aperture imaging and coherent-light detection technology, the weak signal identification capacity of Synthetic Aperture Ladar (SAL reaches the photo level, and the image resolution exceeds the diffraction limit of the telescope to obtain high-resolution images irrespective to ranges. This paper introduces SAL, including the development path, technology characteristics, and the restriction of imaging swath. On the basis of this, we propose to integrate the SAL technology for extending its swath. By analyzing the scanning-operation mode and the signal model, the paper explicitly proposes that the former mode will be the developmental trend of the SAL technology. This paper also introduces the flight demonstrations of the SAL and the imaging results of remote targets, showing the potential of the SAL in long-range, high-resolution, and scanning-imaging applications. The technology and the theory of the scanning mode of SAL compensates for the defects related to the swath and operation efficiency of the current SAL. It provides scientific foundation for the SAL system applied in wide swath, high resolution earth observation, and the ISAL system applied in space-targets imaging.

  17. A comparison of spotlight synthetic aperture radar image formation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Knittle, C.D.; Doren, N.E.; Jakowatz, C.V.

    1996-10-01

    Spotlight synthetic aperture radar images can be formed from the complex phase history data using two main techniques: (1) polar-to-cartesian interpolation followed by two-dimensional inverse Fourier transform (2DFFT), and (2) convolution backprojection (CBP). CBP has been widely used to reconstruct medical images in computer aided tomography, and only recently has been applied to form synthetic aperture radar imagery. It is alleged that CBP yields higher quality images because (1) all the Fourier data are used and (2) the polar formatted data is used directly to form a 2D Cartesian image and therefore 2D interpolation is not required. This report compares the quality of images formed by CBP and several modified versions of the 2DFFT method. We show from an image quality point of view that CBP is equivalent to first windowing the phase history data and then interpolating to an exscribed rectangle. From a mathematical perspective, we should expect this conclusion since the same Fourier data are used to form the SAR image. We next address the issue of parallel implementation of each algorithm. We dispute previous claims that CBP is more readily parallelizable than the 2DFFT method. Our conclusions are supported by comparing execution times between massively parallel implementations of both algorithms, showing that both experience similar decreases in computation time, but that CBP takes significantly longer to form an image.

  18. Frequency-domain synthetic aperture focusing for helical ultrasonic imaging

    Science.gov (United States)

    Jin, H.; Chen, J.; Wu, E.; Yang, K.

    2017-04-01

    The synthetic aperture focusing technique (SAFT) is widely used to provide significant improvement in the lateral resolution of ultrasonic images. Frequency-domain SAFT has shown higher accuracy and greater efficiency than time-domain SAFT. However, frequency-domain SAFT should be helix-based for ultrasonic scanning of cylindrical structures such as pipes and axletrees. In this study, a frequency-domain SAFT is proposed for 3D helical ultrasonic imaging applications. This technique adjusts the phase spectra of the images to complete the synthetic aperture focusing process. The focused image is precise because the proposed algorithm is established on the basis of the wave equation in a helical coordinate system. In addition, the algorithm can efficiently separate out point scatterers and present volume scatterers. The experimental results show that the proposed algorithm yields lower side lobes and enhances the angular resolution of the ultrasonic image to approximately 1°- 1.5°, which is much better than the performance of time-domain SAFT. The maximum deviations are only 0.6 mm, 0.5°, and 0.4 mm along the r-axes, θ-axes, and z-axes, respectively, which are appropriate for normal ultrasonic nondestructive testing.

  19. 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.

  20. Cardiac In-vivo Measurements Using Synthetic Transmit Aperture Ultrasound

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Hassager, Christian

    2006-01-01

    This paper investigates the feasibility of acquiring cardiac images using synthetic transmit aperture (STA) ultrasound. Focusing in STA is done by beamforming all points in the image for every emission, creating a low-resolution image. The low-resolution images for each emission are summed......, together with the RASMUS experimental ultrasound scanner. Both transducers have a pitch of half a wavelength. To ensure an adequate signal-to-noise ratio, a 20 mus non-linear frequency modulated chirp and a 7-element de-focused virtual source were used for transmission. The number of virtual sources used...... the first and last emission, and allows a frame rate of up to 555 frames/s. The sparse sequence is interleaved with the full sequence to allow a better comparison between the two techniques. A measurement of a point spread phantom shows a FWHM for the full scan sequences of 1.29 mm and 0.66 mm for the 64...

  1. 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.

  2. Synthetic-Aperture Coherent Imaging From A Circular Path

    Science.gov (United States)

    Jin, Michael Y.

    1995-01-01

    Imaging algorithms based on exact point-target responses. Developed for use in reconstructing image of target from data gathered by radar, sonar, or other transmitting/receiving coherent-signal sensory apparatus following circular observation path around target. Potential applications include: Wide-beam synthetic-aperture radar (SAR) from aboard spacecraft in circular orbit around target planet; SAR from aboard airplane flying circular course at constant elevation around central ground point, toward which spotlight radar beam pointed; Ultrasonic reflection tomography in medical setting, using one transducer moving in circle around patient or else multiple transducers at fixed positions on circle around patient; and Sonar imaging of sea floor to high resolution, without need for large sensory apparatus.

  3. An acceleration framework for synthetic aperture radar algorithms

    Science.gov (United States)

    Kim, Youngsoo; Gloster, Clay S.; Alexander, Winser E.

    2017-04-01

    Algorithms for radar signal processing, such as Synthetic Aperture Radar (SAR) are computationally intensive and require considerable execution time on a general purpose processor. Reconfigurable logic can be used to off-load the primary computational kernel onto a custom computing machine in order to reduce execution time by an order of magnitude as compared to kernel execution on a general purpose processor. Specifically, Field Programmable Gate Arrays (FPGAs) can be used to accelerate these kernels using hardware-based custom logic implementations. In this paper, we demonstrate a framework for algorithm acceleration. We used SAR as a case study to illustrate the potential for algorithm acceleration offered by FPGAs. Initially, we profiled the SAR algorithm and implemented a homomorphic filter using a hardware implementation of the natural logarithm. Experimental results show a linear speedup by adding reasonably small processing elements in Field Programmable Gate Array (FPGA) as opposed to using a software implementation running on a typical general purpose processor.

  4. In Vivo Real Time Volumetric Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Rasmussen, Morten Fischer; Brandt, Andreas Hjelm

    2015-01-01

    Synthetic aperture (SA) imaging can be used to achieve real-time volumetric ultrasound imaging using 2-D array transducers. The sensitivity of SA imaging is improved by maximizing the acoustic output, but one must consider the limitations of an ultrasound system, both technical and biological....... This paper investigates the in vivo applicability and sensitivity of volumetric SA imaging. Utilizing the transmit events to generate a set of virtual point sources, a frame rate of 25 Hz for a 90° x 90° field-of-view was achieved. Data were obtained using a 3.5 MHz 32 x 32 elements 2-D phased array...... transducer connected to the experimental scanner (SARUS). Proper scaling is applied to the excitation signal such that intensity levels are in compliance with the U.S. Food and Drug Administration regulations for in vivo ultrasound imaging. The measured Mechanical Index and spatial-peak- temporal...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

  6. Time-frequency analysis of synthetic aperture radar signals

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Brooks [Univ. of California, Davis, CA (United States)

    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.

  7. In-vivo synthetic aperture flow imaging in medical ultrasound

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2003-01-01

    is used for generating a parabolic laminar flow, and a research scanner is used for acquiring RF data from individual transducer elements. A reference profile is calculated from a mass flow meter. The parabolic velocity profile is estimated using the new approach with a relative standard deviation of 2......A new method for acquiring flow images using synthetic aperture techniques in medical ultrasound is presented. The new approach makes it possible to have a continuous acquisition of flow data throughout the whole image simultaneously, and this can significantly improve blood velocity estimation....... Any type of filter can be used for discrimination between tissue and blood flow without initialization, and the number of lines used for velocity estimation is limited only by the nonstationarity of the flow. The new approach is investigated through both simulations and measurements. A flow rig...

  8. Experiences with synthetic aperture focusing technique in the field

    Science.gov (United States)

    Schmitz; Chakhlov; Muller

    2000-03-01

    The detection and evaluation of defects in industrial components relies strongly on ultrasonic inspection techniques. Distance gain size (DG) or reference reflector methods can be improved concerning their localization, signal-to-noise ratio and sizing accuracy by the synthetic aperture focusing technique (SAFT). To obtain a high quality image, parameters like focal probe versus contact technique probe, achieved resolution or features of SAFT images compared with B-scan images are discussed. The implementation of SAFT in a CAD environment allows us to present stacked 2D reconstructions dynamically. On a cladded testblock with half-penny shaped cracks the advantage of combining CAD with SAFT is shown. A 3D SAFT example finalizes the overview of two decades of experience in applying this technique.

  9. 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.

  10. Determination of ocean wave heights from synthetic aperture radar imagery

    Science.gov (United States)

    Jain, A.

    1977-01-01

    A calculation is presented for the cross-correlation of the radar images obtained by processing the same signal data over different portions of the chirp spectrum bandwidth as a function of the center frequency spacings for these portions. This is shown to be proportional to the square of the product of the characteristic function for ocean wave heights and the pupil function describing the chirp spectrum bandwidth used in the processing. Measurements of this function for ocean wave imagery over the coast of Alaska, the North Atlantic, and Monterey Bay, California, and correlation with the significant wave heights reported from ground truth data indicate that the synthetic aperture radar instrument can be used for providing wave height information in addition to the ocean wave imagery.

  11. Rocking convex array used for 3D synthetic aperture focusing

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Pedersen, M M

    2008-01-01

    Volumetric imaging can be performed using 1D arrays in combination with mechanical motion. Outside the elevation focus of the array, the resolution and contrast quickly degrade compared to the azimuth plane, because of the fixed transducer focus. The purpose of this paper is to use synthetic...... aperture focusing (SAF) for enhancing the elevation focusing for a convex rocking array, to obtain a more isotropic point spread function. This paper presents further development of the SAF method, which can be used with curved array combined with a rocking motion. The method uses a virtual source (VS......) for defocused multi-element transmit, and another VS in the elevation focus point. This allows a direct time-of-flight (ToF) to be calculated for a given 3D point. The method is evaluated using simulations from Field II and by measurements using the RASMUS experimental scanner with a 4.5 MHz convex array (GE...

  12. Synthetic Aperture Beamforming in Ultrasound using Moving Arrays

    DEFF Research Database (Denmark)

    Andresen, Henrik

    the focus point and reduces temporal resolution. For better image quality it is desirable to achieve a good resolution at a large range of depths, and achieving a volume-rate fast enough to visualize the dynamics of the investigated organ. A method showing the possibility of meeting both these challenges...... is synthetic aperture focusing (SAF). A full dynamic focusing is possible in both transmit and receive as well as the possibility of imaging an entire volume with only a few emission. The resolution of the resulting volume can be improved by using more emissions, giving a trade-off between temporal and spatial...... resolution. A challenge with SAF is a large increase in processing requirements, especially for 3D systems. Ideally the method is able to achieve a good image quality for all depths in the volume with a time-resolution fast enough for cardiac images. This will allow better diagnoses with fewer scans, making...

  13. 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...... distribution. Based on this distribution a test statistic for equality of two such matrices and an associated asymptotic probability for obtaining a smaller value of the test statistic are given and applied to segmentation, change detection and edge detection in polarimetric SAR data. In a case study EMISAR L......-band data from 17 April 1998 and 20 May 1998 covering agricultural fields near Foulum, Denmark, are used....

  14. 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

  15. Shuttle Imaging Radar-C mission operations - Technology test bed for Earth Observing System synthetic aperture radar

    Science.gov (United States)

    Trimble, J. P.; Collins, C. E.

    1992-01-01

    The mission operations for the Space Radar Lab (SRL), particularly in the areas of real-time replanning and science activity coordination, are presented. The two main components of SRL are the Shuttle Imaging Radar-C and the X-Band Synthetic Aperture Radar. The Earth Observing System SAR will be a multispectral, multipolarization radar satellite that will provide information over an entire decade, permitting scientists to monitor large-scale changes in the earth's environment over a long period of time.

  16. Synthetic aperture imaging in astronomy and aerospace: introduction.

    Science.gov (United States)

    Creech-Eakman, Michelle J; Carney, P Scott; Buscher, David F; Shao, Michael

    2017-05-01

    Aperture synthesis methods allow the reconstruction of images with the angular resolutions exceeding that of extremely large monolithic apertures by using arrays of smaller apertures together in combination. In this issue we present several papers with techniques relevant to amplitude interferometry, laser radar, and intensity interferometry applications.

  17. 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.

  18. Explosive hazard detection using synthetic aperture acoustic sensing

    Science.gov (United States)

    Brewster, E.; Keller, J. M.; Stone, K.; Popescu, M.

    2016-05-01

    In this paper, we develop an approach to detect explosive hazards designed to attack vehicles from the side of a road, using a side looking synthetic aperture acoustic (SAA) sensor. This is done by first processing the raw data using a back-projection algorithm to form images. Next, an RX prescreener creates a list of possible targets, each with a designated confidence. Initial experiments are performed on libraries of the highest confidence hits for both target and false alarm classes generated by the prescreener. Image chips are extracted using pixel locations derived from the target's easting and northing. Several feature types are calculated from each image chip, including: histogram of oriented gradients (HOG), and generalized column projection features where the column aggregator takes the form of the minimum, maximum, mean, median, mode, standard deviation, variance, and the one-dimensional fast Fourier transform (FFT). A support vector machine (SVM) classifier is then utilized to evaluate feature type performance during training and testing in order to determine whether the two classes are separable. This will be used to build an online detection system for road-side explosive hazards.

  19. Synthetic Aperture Focusing Technique 3D-CAD-SAFT

    Science.gov (United States)

    Schmitz, V.; Kröning, M.; Chakhlov, S.; Fischer, W.

    2000-05-01

    Till the 80's ultrasonic holography has been used as an analyzing technique, a procedure which has been replaced by the Synthetic Aperture Focusing Technique "SAFT." This technique has been applied on metallic components in different power plants, mostly on pipe systems on pressure vessels or on specimen made of composite or concrete material. SAFT exists in different versions, either in 2D or 3D, for plane or arbitrarily shaped surfaces, for pulse echo or pitch- and catch arrangements. The defect sizes ranged from 100 μm in turbine shafts till fractures of meters in research pressure vessels. The paper covers the lastest results of the SAFT-reconstruction technique under Windows NT which has been guided by the experience obtained in the field. It contributes to the currently discussed question of the possible benefit using TOFD—techniques versus pulse echo techniques; the target has been a fatigue crack in a pipe segment which was investigated by different insonification angles, wave modes and probe arrangements. The results are evaluated with respect to signal-to-noise ratio improvement; problems of TOFD are demonstrated using an animation procedure which allows to walk through the weld in three orthogonal directions. A special example will be shown from a bore hole inspection of water power station valves where the reconstruction procedure follows the radial axial insonification planes. The multi-line SAFT images can be cut according to the situation of the crack position and orientation.

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

    Directory of Open Access Journals (Sweden)

    Shuanghui Zhang

    2016-04-01

    Full Text Available 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.

  1. 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.

  2. 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.

  3. Feasibility Study of Synthetic Aperture Radar - Adaptability of the Payload to KOMPSAT Platform

    Directory of Open Access Journals (Sweden)

    Young-Soo Kim

    2002-09-01

    Full Text Available Synthetic Aperture Radar (SAR has been used for mapping the surface geomorphology of cloudy planets like Venus as well as the Earth. The cloud-free Mars is also going to be scanned by SAR in order to detect buried water channels and other features under the very shallow subsurface of the ground. According to the 'Mid and Long-term National Space Development Plan' of Korea, SAR satellites, in addition to the EO (Electro-Optical satellites, are supposed to be developed in the frame of the KOMPSAT (Korean Multi-Purpose Satellite program. Feasibility of utilizing a SAR payload on KOMPSAT platform has been studied by KARI in collaboration with Astrium U.K. The purpose of the SAR program is Scientific and Civil applications on the Earth. The study showed that KOMPSAT-2 platform can accommodate a small SAR like Astrium's MicroSAR. In this paper, system aspects of the satellite design are presented, such as mission scenario, operation concept, and capabilities. The spacecraft design is also discussed and conclusion is followed.

  4. Research on Synthetic Aperture Radar Processing for the Spaceborne Sliding Spotlight Mode.

    Science.gov (United States)

    Shen, Shijian; Nie, Xin; Zhang, Xinggan

    2018-02-03

    Gaofen-3 (GF-3) is China' first C-band multi-polarization synthetic aperture radar (SAR) satellite, which also provides the sliding spotlight mode for the first time. Sliding-spotlight mode is a novel mode to realize imaging with not only high resolution, but also wide swath. Several key technologies for sliding spotlight mode in spaceborne SAR with high resolution are investigated in this paper, mainly including the imaging parameters, the methods of velocity estimation and ambiguity elimination, and the imaging algorithms. Based on the chosen Convolution BackProjection (CBP) and PFA (Polar Format Algorithm) imaging algorithms, a fast implementation method of CBP and a modified PFA method suitable for sliding spotlight mode are proposed, and the processing flows are derived in detail. Finally, the algorithms are validated by simulations and measured data.

  5. Spaceborne synthetic aperture radar signal processing using FPGAs

    Science.gov (United States)

    Sugimoto, Yohei; Ozawa, Satoru; Inaba, Noriyasu

    2017-10-01

    Synthetic Aperture Radar (SAR) imagery requires image reproduction through successive signal processing of received data before browsing images and extracting information. The received signal data records of the ALOS-2/PALSAR-2 are stored in the onboard mission data storage and transmitted to the ground. In order to compensate the storage usage and the capacity of transmission data through the mission date communication networks, the operation duty of the PALSAR-2 is limited. This balance strongly relies on the network availability. The observation operations of the present spaceborne SAR systems are rigorously planned by simulating the mission data balance, given conflicting user demands. This problem should be solved such that we do not have to compromise the operations and the potential of the next-generation spaceborne SAR systems. One of the solutions is to compress the SAR data through onboard image reproduction and information extraction from the reproduced images. This is also beneficial for fast delivery of information products and event-driven observations by constellation. The Emergence Studio (Sōhatsu kōbō in Japanese) with Japan Aerospace Exploration Agency is developing evaluation models of FPGA-based signal processing system for onboard SAR image reproduction. The model, namely, "Fast L1 Processor (FLIP)" developed in 2016 can reproduce a 10m-resolution single look complex image (Level 1.1) from ALOS/PALSAR raw signal data (Level 1.0). The processing speed of the FLIP at 200 MHz results in twice faster than CPU-based computing at 3.7 GHz. The image processed by the FLIP is no way inferior to the image processed with 32-bit computing in MATLAB.

  6. 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.

  7. Spaceborne L-band Radiometers: Push-broom or Synthetic Aperture?

    DEFF Research Database (Denmark)

    Skou, Niels

    2004-01-01

    L-band radiometers can measure ocean salinity and soil moisture from space. A synthetic aperture radiometer system, SMOS, is under development by ESA for launch in 2007. A real aperture push-broom system, Aquarius, has been approved by NASA for launch in 2008. Pros et cons of the two fundamentally...

  8. A spaceborne synthetic aperture radiometer simulated by the TUD demonstration model

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1994-01-01

    The TUD synthetic aperture radiometer demonstration model consists of a 2-channel X-band correlation radiometer with two horn antennas and an antenna mounting structure enabling the horns to be mounted in relevant positions within a certain aperture. The cross correlation of the signals from the 2...

  9. 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...

  10. Subsidence feature discrimination using deep convolutional neral networks in synthetic aperture radar imagery

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2017-07-01

    Full Text Available International Geoscience and Remote Sensing Symposium (IGARSS), 23-28 July 2017, Fort Worth, TX, USA SUBSIDENCE FEATURE DISCRIMINATION USING DEEP CONVOLUTIONAL NEURAL NETWORKS IN SYNTHETIC APERTURE RADAR IMAGERY Schwegmann, Colin P Kleynhans, Waldo...

  11. Applicability of Synthetic Aperture Radar Wind Retrievals on Offshore Wind Resources Assessment in Hangzhou Bay, China

    Directory of Open Access Journals (Sweden)

    Rui Chang

    2014-05-01

    Full Text Available In view of the high cost and sparse spatial resolution of offshore meteorological observations, ocean winds retrieved from satellites are valuable in offshore wind resource assessment as a supplement to in situ measurements. This study examines satellite synthetic aperture radar (SAR images from ENVISAT advanced SAR (ASAR for mapping wind resources with high spatial resolution. Around 181 collected pairs of wind data from SAR wind maps and from 13 meteorological stations in Hangzhou Bay are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a standard deviation (SD of 1.99 m/s and correlation coefficient of R = 0.67. The model wind directions, which are used as input for the SAR wind speed retrieval, show a high correlation coefficient (R = 0.89 but a large standard deviation (SD = 42.3° compared to in situ observations. The Weibull probability density functions are compared at one meteorological station. The SAR-based results appear not to estimate the mean wind speed, Weibull scale and shape parameters and wind power density from the full in situ data set so well due to the lower number of satellite samples. Distributions calculated from the concurrent 81 SAR and in situ samples agree well.

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

    OpenAIRE

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

    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 ea...

  13. The Information Content of Interferometric Synthetic Aperture Radar: Vegetation and Underlying Surface Topography

    Science.gov (United States)

    Treuhaft, Robert N.

    1996-01-01

    This paper first gives a heuristic description of the sensitivity of Interferometric Synthetic Aperture Radar to vertical vegetation distributions and underlying surface topography. A parameter estimation scenario is then described in which the Interferometric Synthetic Aperture Radar cross-correlation amplitude and phase are the observations from which vegetation and surface topographic parameters are estimated. It is shown that, even in the homogeneous-layer model of the vegetation, the number of parameters needed to describe the vegetation and underlying topography exceeds the number of Interferometric Synthetic Aperture Radar observations for single-baseline, single-frequency, single-incidence-angle, single-polarization Interferometric Synthetic Aperture Radar. Using ancillary ground-truth data to compensate for the underdetermination of the parameters, forest depths are estimated from the INSAR data. A recently-analyzed multibaseline data set is also discussed and the potential for stand-alone Interferometric Synthetic Aperture Radar parameter estimation is assessed. The potential of combining the information content of Interferometric Synthetic Aperture Radar with that of infrared/optical remote sensing data is briefly discussed.

  14. Model-Based Information Extraction From Synthetic Aperture Radar Signals

    Science.gov (United States)

    Matzner, Shari A.

    2011-07-01

    Synthetic aperture radar (SAR) is a remote sensing technology for imaging areas of the earth's surface. SAR has been successfully used for monitoring characteristics of the natural environment such as land cover type and tree density. With the advent of higher resolution sensors, it is now theoretically possible to extract information about individual structures such as buildings from SAR imagery. This information could be used for disaster response and security-related intelligence. SAR has an advantage over other remote sensing technologies for these applications because SAR data can be collected during the night and in rainy or cloudy conditions. This research presents a model-based method for extracting information about a building -- its height and roof slope -- from a single SAR image. Other methods require multiple images or ancillary data from specialized sensors, making them less practical. The model-based method uses simulation to match a hypothesized building to an observed SAR image. The degree to which a simulation matches the observed data is measured by mutual information. The success of this method depends on the accuracy of the simulation and on the reliability of the mutual information similarity measure. Electromagnetic theory was applied to relate a building's physical characteristics to the features present in a SAR image. This understanding was used to quantify the precision of building information contained in SAR data, and to identify the inputs needed for accurate simulation. A new SAR simulation technique was developed to meet the accuracy and efficiency requirements of model-based information extraction. Mutual information, a concept from information theory, has become a standard for measuring the similarity between medical images. Its performance in the context of matching a simulation image to a SAR image was evaluated in this research, and it was found to perform well under certain conditions. The factors that affect its performance

  15. Screening of Earthen Levees Using Synthetic Aperture Radar

    Science.gov (United States)

    Aanstoos, J. V.; O'Hara, C.; Prasad, S.; Dabbiru, L.; Nobrega, R.; Lee, M.

    2009-12-01

    Earthen levees protect large areas of populated and cultivated land in the US from flooding. As shown recently with hurricanes Katrina and Ike and the recent floods in the Midwest, the potential loss of life and property associated with the catastrophic failure of levees can be extremely large. Over the entire US, there are over 100,000 miles of levee structures of varying designs and conditions. Currently, there are limited processes in place to prioritize the monitoring of large numbers of dam and levee structures. Levee managers and federal agencies need to assess levee health rapidly with robust techniques that identify, classify and prioritize levee vulnerabilities with lower costs than traditional soil-boring programs, which can cost many of millions of dollars and provide information about the subsurface only in the immediate vicinity of a small-diameter borehole. This paper reports preliminary results of a project studying the use of airborne synthetic aperture radar (SAR) as an aid to the levee screening process. The SAR sensor being studied is the NASA UAVSAR (Unmanned Aerial Vehicle SAR), a fully polarimetric L-band SAR which is specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. The instrument is capable of sub-meter ground sample distance. NASA has imaged with this instrument 230 km of levees along the lower Mississippi River for use in this study. SAR interferometric mode is capable of identifying vertical displacements on the order of a few millimeters. Its multipolarization measurements can penetrate soil to as much as one meter depth. Thus it is valuable in detecting changes in levees that will be key inputs to a levee vulnerability classification system. Once vulnerable levee reaches have been identified, further actions such as more detailed examination or repairs can be focused on these higher-priority sections. We report on the use of various feature detection algorithms being applied

  16. The implementation of temporal synthetic aperture imaging for ultrafast optical processing

    Science.gov (United States)

    Zhao, Xiaoxiang; Xiao, Shaoqiu; Gong, Cheng; Yi, Tao; Liu, Shenye

    2017-12-01

    A new technique of temporal imaging, called temporal synthetic aperture imaging (TSAI), is proposed to achieve higher time resolution of the imaging system for ultrafast optical processing. The proposed technique combines several of independent small-aperture systems together to get a higher time resolution and better image quality as a large-aperture system. It can solve the problem that an oversized aperture time lens is difficult to achieve in practice. In this paper, after analyzing the filtering effect, a novel implementation method of TSAI is presented. In order to verify the correctness, we demonstrate a decuple magnification of a signal with two 1ps width pulse separated 2ps, using a synthetic aperture by the system simulation.

  17. GPU-based minimum variance beamformer for synthetic aperture imaging of the eye.

    Science.gov (United States)

    Yiu, Billy Y S; Yu, Alfred C H

    2015-03-01

    Minimum variance (MV) beamforming has emerged as an adaptive apodization approach to bolster the quality of images generated from synthetic aperture ultrasound imaging methods that are based on unfocused transmission principles. In this article, we describe a new high-speed, pixel-based MV beamforming framework for synthetic aperture imaging to form entire frames of adaptively apodized images at real-time throughputs and document its performance in swine eye imaging case examples. Our framework is based on parallel computing principles, and its real-time operational feasibility was realized on a six-GPU (graphics processing unit) platform with 3,072 computing cores. This framework was used to form images with synthetic aperture imaging data acquired from swine eyes (based on virtual point-source emissions). Results indicate that MV-apodized image formation with video-range processing throughput (>20 fps) can be realized for practical aperture sizes (128 channels) and frames with λ/2 pixel spacing. Also, in a corneal wound detection experiment, MV-apodized images generated using our framework revealed apparent contrast enhancement of the wound site (10.8 dB with respect to synthetic aperture images formed with fixed apodization). These findings indicate that GPU-based MV beamforming can, in real time, potentially enhance image quality when performing synthetic aperture imaging that uses unfocused firings. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  18. Synthetic aperture imaging by using spatial modulation diversity technology with stochastic parallel gradient descent algorithm.

    Science.gov (United States)

    Ma, Haotong; Xie, Zongliang; Long, Xuejun; Qi, Bo; Ren, Ge; Shi, Jianliang; Cui, Zhangang; Jiang, Yang; Xu, Xiaojun

    2015-06-01

    In this paper, we propose and demonstrate the synthetic aperture imaging by using spatial modulation diversity technology with stochastic parallel gradient descent (SPGD) algorithm. Instead of creating diversity images by means of focus adjustments, the technology, proposed in this paper, creates diversity images by modulating the transmittance of individual sub-aperture of multi-aperture system, respectively. Specifically, spatial modulation is realized by switching off the transmittance of each sub-aperture with electrical shutters, alternately. Based on these multi diversity images, SPGD algorithm is used for adaptively optimizing the coefficients of Zernike polynomials to reconstruct the real phase distortions of multi-aperture system and to restore the near-diffraction-limited image of object. Numerical simulation and experimental results show that this technology can be used for joint estimation of both pupil aberrations and an high resolution image of the object, successfully. The technology proposed in this paper can have wide applications in segmented and multi-aperture imaging systems.

  19. Application of a matched filter approach for finite aperture transducers for the synthetic aperture imaging of defects.

    Science.gov (United States)

    Satyanarayan, L; Muralidharan, Ajith; Krishnamurthy, Chittivenkata; Balasubramaniam, Krishnan

    2010-06-01

    The suitability of the synthetic aperture imaging of defects using a matched filter approach on finite aperture transducers was investigated. The first part of the study involved the use a finite-difference time-domain (FDTD) algorithm to simulate the phased array ultrasonic wave propagation in an aluminum block and its interaction with side-drilled hole-like defects. B-scans were generated using the FDTD method for three active aperture transducer configurations of the phased array (a) single element and (b) 16-element linear scan mode, and (c) 16-element steering mode. A matched filter algorithm (MFA) was developed using the delay laws and the spatial impulse response of a finite size rectangular phased array transducer. The conventional synthetic aperture focusing technique (SAFT) algorithm and the MFA were independently applied on the FDTD signals simulated with the probe operating at a center frequency of 5 MHz and the processed B-scans were compared. The second part of the study investigated the capability of the MFA approach to improve the SNR. Gaussian white noise was added to the FDTD generated defect signals. The noisy B-scans were then processed using the SAFT and the MFA and the improvements in the SNR were estimated. The third part of the study investigated the application of the MFA to image and size surface-crack-like defects in pipe specimens obtained using a 45 degrees steered beam from a phased array probe. These studies confirm that MFA is an alternative to SAFT with little additional computational burden. It can also be applied blindly, like SAFT, to effect synthetic focusing with distinct advantages in treating finite transducer effects, and in handling steered beam inspections. Finally, limitations of the MFA in dealing with larger-sized transducers are discussed.

  20. Application of Linear Prediction Technique to Passive Synthetic Aperture Processing

    OpenAIRE

    Yong Jin; Min Jiang; Yunshan Hou; Jianguo Huang

    2010-01-01

    A method for the synthesis of an aperture with improved angular resolution and array gain is described. The proposed method explores the merit of linear prediction technique to improve the performance of conventional ETAM (extended towed array measurements) method. Previous efforts to improve the ETAM method generally focused on how to get more accurate estimation of overlap correlator, with an aim to reduce bearing estimation variance. In this paper, however, we discuss how to further impro...

  1. Analysis of Features for Synthetic Aperture Radar Target Classification

    Science.gov (United States)

    2015-03-26

    Process. . . . . . . . . . . . . . . 28 3.4 Segmented Pixels With the Ideal Mapping of Extracted Attributes to Canonical Shapes of Toyota Camry at 30... Toyota Camry, Formed with 20 Degree Apertures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.10 Histogram of gradients of a cell of...The kernel in Equation (2.32) is the dot product of xi and x j. The vector α∗ that maximizes the primal Lagrangian in Equation (2.32) while also

  2. 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.

  3. Preliminary Experimental Verification of Synthetic Aperture Flow Imaging Using a Dual Stage Beamformer Approach

    DEFF Research Database (Denmark)

    Li, Ye; Jensen, Jørgen Arendt

    2011-01-01

    A dual stage beamformer method for synthetic aperture flow imaging has been developed. The motivation is to increase the frame rate and still maintain a beamforming quality sufficient for flow estimation that is possible to implement in a commercial scanner. With the new method high resolution...... images can be obtained continuously, which will highly increase the frame rate. The flow velocity is estimated by using a time-domain cross-correlation technique. The approach is investigated through experiments with the SARUS scanner (Synthetic Aperture Real-time Ultrasound System). A flow rig generates...

  4. Directional synthetic aperture flow imaging using a dual stage beamformer approach

    DEFF Research Database (Denmark)

    Li, Ye; Jensen, Jørgen Arendt

    2011-01-01

    A new method for directional synthetic aperture flow imaging using a dual stage beamformer approach is presented. The velocity estimation is angle independent and the amount of calculations is reduced compared to full synthetic aperture, but still maintains all the advantages at the same time.......3% and bias of 6.4% at 65 were achieved in the simulations, and 4.3% and 4.2% for the experimental measurements. A color flow map image was made in 48 emissions corresponding to a frame rate of 83 frames/s....

  5. Volumetric Synthetic Aperture Imaging with a Piezoelectric 2-D Row-Column Probe

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Christiansen, Thomas Lehrmann

    2016-01-01

    The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row-column addres......The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row...

  6. Implementation of Tissue Harmonic Synthetic Aperture Imaging on a Commercial Ultrasound System

    DEFF Research Database (Denmark)

    Rasmussen, Joachim; Hemmsen, Martin Christian; Madsen, Signe Sloth

    2012-01-01

    This paper presents an imaging technique for synthetic aperture (SAI) tissue harmonic imaging (THI) on a commercial ultrasound system. Synthetic aperture sequential beamforming (SASB) is combined with a pulse inversion (PI) technique on a commercial BK 2202 UltraView system. An interleaved scan...... sequence that performs dynamic receive focused (DRF) imaging and SASB, both using PI, is implemented. From each acquisition four images can be created: DRF image, SASB image, tissue harmonic DRF image (DRF-THI), and tissue harmonic SASB image (SASB-THI). For SASB imaging, a fixed transmit and receive focus...

  7. Passive Synthetic Aperture Radar Imaging Using Commercial OFDM Communication Networks

    Science.gov (United States)

    2012-09-13

    imaging area. 24 Falcone and Colone recently presented passive radar work using the 802.11 OFDM WiFi signal [31]. The study demonstrates the practical...φR is 4.3 degrees at both aperture ends. The array is radiated with the generic OFDM pulse. The OFDM symbols use 112 Figure 67. PFA SAR image using a...OFDM WiFi -based passive bistatic radar”. Radar Conference, 2010 IEEE, 516–521. 2010. [32] Flood, J.E. Telecommunication Networks, 2ed. The

  8. An algorithm for operational flood mapping from Synthetic Aperture Radar (SAR data using fuzzy logic

    Directory of Open Access Journals (Sweden)

    L. Pulvirenti

    2011-02-01

    Full Text Available An algorithm developed to map flooded areas from synthetic aperture radar imagery is presented in this paper. It is conceived to be inserted in the operational flood management system of the Italian Civil Protection and can be used in an almost automatic mode or in an interactive mode, depending on the user's needs. The approach is based on the fuzzy logic that is used to integrate theoretical knowledge about the radar return from inundated areas taken into account by means of three electromagnetic scattering models, with simple hydraulic considerations and contextual information. This integration aims at allowing a user to cope with situations, such as the presence of vegetation in the flooded area, in which inundation mapping from satellite radars represents a difficult task. The algorithm is designed to work with radar data at L, C, and X frequency bands and employs also ancillary data, such as a land cover map and a digital elevation model. The flood mapping procedure is tested on an inundation that occurred in Albania on January 2010 using COSMO-SkyMed very high resolution X-band SAR data.

  9. 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.

  10. 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.

  11. Surface deformation monitoring using synthetic aperture radar data

    African Journals Online (AJOL)

    CGS

    particular, time-series analyses of hyper-temporal satellite data has been successfully applied to land cover .... In essence equation. (1) calculates the autocorrelation of the time series and then sums the first k lags of the autocorrelation output. This summation (δ) is then used as a change metric and compared to a threshold ...

  12. Distributed Aperture Coherence-synthetic Radar Joint Antenna Gain Analysis

    Directory of Open Access Journals (Sweden)

    Zhou Baoliang

    2017-08-01

    Full Text Available By the synthesis of multi-radar electromagnetic wave space energy, Distributed Aperture Coherencesynthetic Radar (DACR achieves long-range power detection via multi-radar airspace expansion to realize high-precision target angle measurement. DACR has the advantages of strong survival ability, a high cost- effectiveness ratio, high angular accuracy, strong expandability, and easy realization. In this article, we analyze the joint antenna gain of a non-directional multi-point source and, given the theoretical derivation and simulation analysis, we establish a distributed-array-antenna geometric model, analyze the joint antenna pattern and gain, respectively, and determine that the joint antenna gain is approximately equal to the unit radar number and the unit radar gain product. Lastly, we perform a joint antenna gain simulation using HFSS software to further verify the joint antenna gain results.

  13. 3D Imaging Millimeter Wave Circular Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Renyuan Zhang

    2017-06-01

    Full Text Available In this paper, a new millimeter wave 3D imaging radar is proposed. The user just needs to move the radar along a circular track, and high resolution 3D imaging can be generated. The proposed radar uses the movement of itself to synthesize a large aperture in both the azimuth and elevation directions. It can utilize inverse Radon transform to resolve 3D imaging. To improve the sensing result, the compressed sensing approach is further investigated. The simulation and experimental result further illustrated the design. Because a single transceiver circuit is needed, a light, affordable and high resolution 3D mmWave imaging radar is illustrated in the paper.

  14. Automated global water mapping based on wide-swath orbital synthetic-aperture radar

    Directory of Open Access Journals (Sweden)

    R. S. Westerhoff

    2013-02-01

    Full Text Available This paper presents an automated technique which ingests orbital synthetic-aperture radar (SAR imagery and outputs surface water maps in near real time and on a global scale. The service anticipates future open data dissemination of water extent information using the European Space Agency's Sentinel-1 data. The classification methods used are innovative and practical and automatically calibrated to local conditions per 1 × 1° tile. For each tile, a probability distribution function in the range between being covered with water or being dry is established based on a long-term SAR training dataset. These probability distributions are conditional on the backscatter and the incidence angle. In classification mode, the probability of water coverage per pixel of 1 km × 1 km is calculated with the input of the current backscatter – incidence angle combination. The overlap between the probability distributions of a pixel being wet or dry is used as a proxy for the quality of our classification. The service has multiple uses, e.g. for water body dynamics in times of drought or for urgent inundation extent determination during floods. The service generates data systematically: it is not an on-demand service activated only for emergency response, but instead is always up-to-date and available. We validate its use in flood situations using Envisat ASAR information during the 2011 Thailand floods and the Pakistan 2010 floods and perform a first merge with a NASA near real time water product based on MODIS optical satellite imagery. This merge shows good agreement between these independent satellite-based water products.

  15. 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

  16. 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

  17. 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.

  18. Performance Evaluation of a Synthetic Aperture Real-Time Ultrasound System

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2011-01-01

    This paper evaluates the signal-to-noise ratio, the time stability, and the phase difference of the sampling in the experimental ultrasound scanner SARUS: A synthetic aperture, real-time ultrasound system. SARUS has 1024 independent transmit and receive channels and is capable of handling 2D prob...

  19. Further development of synthetic aperture real-time 3D scanning with a rotating phased array

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Gran, Fredrik

    2003-01-01

    In a precious paper we have presented an approach combing synthetic transmit aperture imaging with a rotating phased array. The method is implemented on a specially made Vermon transducer capable of rotating at 5 Hz. The center frequency of the transducer is 3.2 MHz, and the pitch is 0.22 mm. The...

  20. Vector Velocity Estimation for Portable Ultrasound using Directional Transverse Oscillation and Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    di Ianni, Tommaso; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-01-01

    In this paper, a vector flow imaging method is presented, which combines the directional transverse oscillation approach with synthetic aperture sequential beamforming to achieve an efficient estimation of the velocities. A double oscillating field is synthesized using two sets of focused emissio...

  1. 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

  2. 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

  3. 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

  4. Velocity vector estimation in synthetic aperture flow and B-mode imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2004-01-01

    A method for determining both velocity magnitude and angle in a synthetic aperture ultrasound system is described. The approach uses directional beamforming along the flow direction and cross-correlation to determine velocity magnitude. The angle of the flow is determined from the maximum normali...

  5. Forest-cover-type separation using RADARSAT-1 synthetic aperture radar imagery

    Science.gov (United States)

    Mark D. Nelson; Kathleen T. Ward; Marvin E. Bauer

    2009-01-01

    RADARSAT-1 synthetic aperture radar data, speckle reduction, and texture measures provided for separation among forest types within the Twin Cities metropolitan area, MN, USA. The highest transformed divergence values for 16-bit data resulted from speckle filtering while the highest values for 8-bit data resulted from the orthorectified image, before and after...

  6. 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.

  7. AMBER: An X-band FMCW digital beam forming synthetic aperture radar for a tactical UAV

    NARCIS (Netherlands)

    Graaf, M.W. van der; Otten, M.P.G.; Huizing, A.G.; Tan, R.G.; Caro Cuenca, M.; Ruizenaar, M.G.A.

    2013-01-01

    An X-band Digital Array Synthetic Aperture Radar for a Short Range Tactical UAV is presented. This system is demonstrated on a manned helicopter and motor glider. The Frequency Modulated Continuous Wave radar principle in combination with digital beam forming over 24 receive channels is used to meet

  8. Determining Snow Depth Using Airborne Multi-Pass Interferometric Synthetic Aperture Radar

    Science.gov (United States)

    2013-09-01

    The high albedo of snow greatly impacts the local and global scale radiational balance. The snow decreases the absorption of solar energy...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA DISSERTATION Approved for public release: distribution is unlimited DETERMINING SNOW ...DATES COVERED Dissertation 4. TITLE AND SUBTITLE DETERMINING SNOW DEPTH USING AIRBORNE MULTI-PASS INTERFEROMETRIC SYNTHETIC APERTURE RADAR 5

  9. Sparse synthetic aperture with Fresnel elements (S-SAFE) using digital incoherent holograms

    Science.gov (United States)

    Kashter, Yuval; Rivenson, Yair; Stern, Adrian; Rosen, Joseph

    2015-01-01

    Creating a large-scale synthetic aperture makes it possible to break the resolution boundaries dictated by the wave nature of light of common optical systems. However, their implementation is challenging, since the generation of a large size continuous mosaic synthetic aperture composed of many patterns is complicated in terms of both phase matching and time-multiplexing duration. In this study we present an advanced configuration for an incoherent holographic imaging system with super resolution qualities that creates a partial synthetic aperture. The new system, termed sparse synthetic aperture with Fresnel elements (S-SAFE), enables significantly decreasing the number of the recorded elements, and it is free from positional constrains on their location. Additionally, in order to obtain the best image quality we propose an optimal mosaicking structure derived on the basis of physical and numerical considerations, and introduce three reconstruction approaches which are compared and discussed. The super-resolution capabilities of the proposed scheme and its limitations are analyzed, numerically simulated and experimentally demonstrated. PMID:26367947

  10. Preliminary In-vivo Results For Spatially Coded Synthetic Transmit Aperture Ultrasound Based On Frequency Division

    DEFF Research Database (Denmark)

    Gran, Fredrik; Hansen, Kristoffer Lindskov; Jensen, Jørgen Arendt

    2006-01-01

    This paper investigates the possibility of using spatial coding based on frequency division for in-vivo synthetic transmit aperture (STA) ultrasound imaging. When using spatial encoding for STA, it is possible to use several transmitters simultaneously and separate the signals at the receiver. Th...

  11. K-space model of motion artifacts in synthetic transmit aperture ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2003-01-01

    Synthetic transmit aperture (STA) imaging gives the possibility to acquire an image with only few emissions and is appealing for 3D ultrasound imaging. Even though the number of emissions is low, the change in position of the scatterers prohibits the coherent summations of ultrasound echoes...

  12. 3D synthetic aperture imaging using a virtual source element in the elevation plane

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2000-01-01

    scatterer was positioned 96 mm from the transducer surface. The transducer was translated in the elevation direction from -13 to +13 mm over the scatterer at steps of 0.375 mm. Each of the 70 planes is scanned using synthetic transmit aperture with 8 emissions. The beam-formed RF lines from the planes...

  13. Performance of Scattering Matrix Decomposition and Color Spaces for Synthetic Aperture Radar Imagery

    Science.gov (United States)

    2010-03-01

    Color Spaces and Synthetic Aperture Radar (SAR) Multicolor Imaging. 15 2.3.1 Colorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.3.2...III. Decomposition Techniques on SAR Polarimetry and Colorimetry applied to SAR Imagery...space polarimetric SAR systems. Colorimetry is also introduced in this chapter, presenting the fundamentals of the RGB and CMY color spaces, defined for

  14. Synthetic aperture radar signal data compression using block adaptive quantization

    Science.gov (United States)

    Kuduvalli, Gopinath; Dutkiewicz, Melanie; Cumming, Ian

    1994-01-01

    This paper describes the design and testing of an on-board SAR signal data compression algorithm for ESA's ENVISAT satellite. The Block Adaptive Quantization (BAQ) algorithm was selected, and optimized for the various operational modes of the ASAR instrument. A flexible BAQ scheme was developed which allows a selection of compression ratio/image quality trade-offs. Test results show the high quality of the SAR images processed from the reconstructed signal data, and the feasibility of on-board implementation using a single ASIC.

  15. 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.

  16. Digital off-axis holography with angular multiplexing and synthetic aperture

    Science.gov (United States)

    Wang, Zhaomin; Qu, Weijuan; Yang, Fang; Wen, Yongfu; Anand, Asundi

    2015-07-01

    This paper discusses conventional synthetic-aperture method combined angular multiplexing in digital holography to increase the resolution and to enlarge the field of view at the same time. A structured illumination is used to realize angular multiplexing. A camera is moved by a motorized x-y stage, and scanning is performed at imaging plane. In this way we extend the band-pass for single hologram recording as well as obtain a greater sensor area resulting in a larger numerical aperture (NA). A larger NA enables a more detailed reconstruction combined with a smaller depth of field. Moreover, a phase map of the object is experimentally presented.

  17. Synthetic Aperture Focusing Applied to Imaging Using a Rotating Single Element Transducer

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2007-01-01

    This paper applies the concept of virtual sources and mono-static synthetic aperture focusing (SAF) to 2-dimensional imaging with a single rotating mechanically focused concave element with the objective of improving lateral resolution and signal-to-noise ratio (SNR). The geometrical focal point...... and the radial and angular resolution are extracted at -6 dB and -40 dB. The performance of the setup with a VS at 20 mm is superior to the other setups. Due to the rotation, the synthesized aperture only experiences a moderate expansion, which is not sufficient to reduce the extent of the wide point spread...

  18. Gulf Coast Subsidence: Integration of Geodesy, Geophysical Modeling, and Interferometric Synthetic Aperture Radar Observations

    Science.gov (United States)

    Blom, R. G.; Chapman, B. D.; Deese, R.; Dokka, R. K.; Fielding, E. J.; Hawkins, B.; Hensley, S.; Ivins, E. R.; Jones, C. E.; Kent, J. D.; Liu, Z.; Lohman, R.; Zheng, Y.

    2012-12-01

    The vulnerability of the US Gulf Coast has received increased attention in the years since hurricanes Katrina and Rita. Agencies responsible for the long-term protection of lives and infrastructure require precise estimates of future subsidence and sea level rise. A quantitative, geophysically based methodology can provide such estimates by incorporating geological data, geodetic measurements, geophysical models of non-elastic mechanical behavior at depth, and geographically comprehensive deformation monitoring made possible with measurements from Interferometric Synthetic Aperture Radar (InSAR). To be effective, results must be available to user agencies in a format suitable for integration within existing decision-support processes. Work to date has included analysis of historical and continuing ground-based geodetic measurements. These reveal a surprising degree of complexity, including regions that are subsiding at rates faster than those considered for hurricane protection planning of New Orleans and other coastal communities (http://www.mvn.usace.army.mil/pdf/hps_verticalsettlement.pdf) as well as Louisiana's coastal restoration strategies (http://www.coast2050.gov/2050reports.htm) (Dokka, 2011, J. Geophys. Res., 116, B06403, doi:10.1029/2010JB008008). Traditional geodetic measurements provide precise information at single points, while InSAR observations provide geographically comprehensive measurements of surface deformation at lower vertical precision. Available InSAR data sources include X-, C- and L-band satellite, and NASA/JPL airborne UAVSAR L-band data. The Gulf Coast environment is very challenging for InSAR techniques, especially with systems not designed for interferometry. For example, the shorter wavelength C-band data decorrelates over short time periods requiring more elaborate time-series analysis techniques, with which we've had some success. Meanwhile, preliminary analysis of limited L-Band ALOS/PALSAR satellite data show promise

  19. Effect of external digital elevation model on monitoring of mine subsidence by two-pass differential interferometric synthetic aperture radar

    Science.gov (United States)

    Tao, Qiuxiang; Gao, Tengfei; Liu, Guolin; Wang, Zhiwei

    2017-04-01

    The external digital elevation model (DEM) error is one of the main factors that affect the accuracy of mine subsidence monitored by two-pass differential interferometric synthetic aperture radar (DInSAR), which has been widely used in monitoring mining-induced subsidence. The theoretical relationship between external DEM error and monitored deformation error is derived based on the principles of interferometric synthetic aperture radar (DInSAR) and two-pass DInSAR. Taking the Dongtan and Yangcun mine areas of Jining as test areas, the difference and accuracy of 1:50000, ASTER GDEM V2, and SRTM DEMs are compared and analyzed. Two interferometric pairs of Advanced Land Observing Satellite Phased Array L-band SAR covering the test areas are processed using two-pass DInSAR with three external DEMs to compare and analyze the effect of three external DEMs on monitored mine subsidence in high- and low-coherence subsidence regions. Moreover, the reliability and accuracy of the three DInSAR-monitored results are compared and verified with leveling-measured subsidence values. Results show that the effect of external DEM on mine subsidence monitored by two-pass DInSAR is not only related to radar look angle, perpendicular baseline, slant range, and external DEM error, but also to the ground resolution of DEM, the magnitude of subsidence, and the coherence of test areas.

  20. Identification of Altered Minerals Based on Synthetic Aperture Radar (SAR) For Mineral Exploration in a Tropical Area

    Science.gov (United States)

    Ghiyats Sabrian, Panggea; Saepuloh, Asep; Syafrizal; Naftali Hawu Hede, Arie

    2017-06-01

    Geological investigation by remote sensing using surface physical properties in tropical regions is challenging. To minimize the effects of atmosphere and vegetation in the obtained optical images, we used the synthetic aperture radar (SAR) images. The phased array L-band synthetic aperture radar (PALSAR) onboard the advanced land observing satellite (ALOS) was selected due to ability of the L-band to penetrate clouds and canopy vegetation. The polarimetric decomposition method based on Cloude-Pottier classification was used as the basis for backscattering analyses. The Ciseuti area in West Java, Indonesia was selected as the study site due to the existence of mining activities, including gold and galena mines. The identification is focused on the spatial distribution of prospected minerals regardless of cloud and vegetation canopy. The classified prospect zones could be extended using the Cloude- Pottier polarimetric decomposition into moderate random entropy and alpha double bounce scattering at argillic alterations, moderate random entropy and alpha surface scattering at intermediate argillic alterations, and highly moderate random entropy and alpha volume diffusion at advanced argillic alterations. The entropy and alpha extracted from ALOS PALSAR data based on Cloude-Pottier decomposition were very useful for identifying alteration zones.

  1. Site Monitoring with Synthetic Aperture Radar Satellite Imagery

    DEFF Research Database (Denmark)

    Canty, Morton J.; Nielsen, Allan Aasbjerg

    2017-01-01

    Based on a statistical test for the equality of polarimetric matrices following the complex Wishart distribution and a factorization of the test statistic, change analysis in a time series of multi-look polarimetric SAR data in variance-covariance or polarimetric matrix representation is carried ...

  2. 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.

  3. 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.

  4. Measuring Deformation in Jakarta through Long Term Synthetic Aperture Radar (SAR) Data Analysis

    Science.gov (United States)

    Agustan; Sulaiman, Albertus; Ito, Takeo

    2016-11-01

    Jakarta as a home for more than 10 millions habitant facing complex environmental problems due to physical development that cause physical deformation. Physical deformation issues such as decreasing environmental carrying capacity, land cover changes and land subsidence have occurred. Recent studies shows that the long of shoreline changes in a span of 13 years from 2002 to 2015 around 14 km due to land reclamation in Jakarta bay. Previous studies also concluded that Jakarta suffer a sinking phenomena due to its rapid subsidence rate, approximately 260 mm/year in northern part of Jakarta. During the 2007 to 2011, the land subsidence phenomena in Jakarta was observed by InSAR based on ALOS-PALSAR data and found that the subsided areas only occurred in certain areas, mainly in Pluit and Cengkareng regions, with a subsidence of approximately 70 cm for 4 years. Land subsidence is generally related to geological subsidence i.e. sediment consolidation due to its own weight and tectonic movements; or related to human activities such as withdrawal of ground water and geothermal fluid, oil and gas extraction from underground reservoirs, and collapse of underground mines. The amount of subsidence or uplift can be estimated from the number of concentric fringes that appear in the interferogram. This research utilizes Synthetic Aperture Radar (SAR) data observed from ALOS-2 (L-band) and Sentinel-1 (C-band) satellites. By interfering two single look complex (SLC) images from different observation epoch, it is found that the subsided area that has been identified before continues to subside. This occurs especially in Pluit region and has been revealed by interfering ALOS-2 data up to year 2016. The deformation in this area is approximately 12 cm from November 2015 to September 2016. The process of land reclamation also clearly identified by Sentinel-1 image by series data processing in Sentinels Application Platform (SNAP) software.

  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. Detection of Oil near Shorelines during the Deepwater Horizon Oil Spill Using Synthetic Aperture Radar (SAR

    Directory of Open Access Journals (Sweden)

    Oscar Garcia-Pineda

    2017-06-01

    Full Text Available During any marine oil spill, floating oil slicks that reach shorelines threaten a wide array of coastal habitats. To assess the presence of oil near shorelines during the Deepwater Horizon (DWH oil spill, we scanned the library of Synthetic Aperture Radar (SAR imagery collected during the event to determine which images intersected shorelines and appeared to contain oil. In total, 715 SAR images taken during the DWH spill were analyzed and processed, with 188 of the images clearly showing oil. Of these, 156 SAR images showed oil within 10 km of the shoreline with appropriate weather conditions for the detection of oil on SAR data. We found detectable oil in SAR images within 10 km of the shoreline from west Louisiana to west Florida, including near beaches, marshes, and islands. The high number of SAR images collected in Barataria Bay, Louisiana in 2010 allowed for the creation of a nearshore oiling persistence map. This analysis shows that, in some areas inside Barataria Bay, floating oil was detected on as many as 29 different days in 2010. The nearshore areas with persistent floating oil corresponded well with areas where ground survey crews discovered heavy shoreline oiling. We conclude that satellite-based SAR imagery can detect oil slicks near shorelines, even in sheltered areas. These data can help assess potential shoreline oil exposure without requiring boats or aircraft. This method can be particularly helpful when shoreline assessment crews are hampered by difficult access or, in the case of DWH, a particularly large spatial and temporal spill extent.

  7. Improved measurements of mean sea surface velocity in the Nordic Seas from synthetic aperture radar

    Science.gov (United States)

    Wergeland Hansen, Morten; Johnsen, Harald; Engen, Geir; Øie Nilsen, Jan Even

    2017-04-01

    The warm and saline surface Atlantic Water (AW) flowing into the Nordic Seas across the Greenland-Scotland ridge transports heat into the Arctic, maintaining the ice-free oceans and regulating sea-ice extent. The AW influences the region's relatively mild climate and is the northern branch of the global thermohaline overturning circulation. Heat loss in the Norwegian Sea is key for both heat transport and deep water formation. In general, the ocean currents in the Nordic Seas and the North Atlantic Ocean is a complex system of topographically steered barotropic and baroclinic currents of which the wind stress and its variability is a driver of major importance. The synthetic aperture radar (SAR) Doppler centroid shift has been demonstrated to contain geophysical information about sea surface wind, waves and current at an accuracy of 5 Hz and pixel spacing of 3.5 - 9 × 8 km2. This corresponds to a horizontal surface velocity of about 20 cm/s at 35° incidence angle. The ESA Prodex ISAR project aims to implement new and improved SAR Doppler shift processing routines to enable reprocessing of the wide swath acquisitions available from the Envisat ASAR archive (2002-2012) at higher resolution and better accuracy than previously obtained, allowing combined use with Sentinel-1 and Radarsat-2 retrievals to build timeseries of the sea surface velocity in the Nordic Seas. Estimation of the geophysical Doppler shift from new SAR Doppler centroid shift retrievals will be demonstrated, addressing key issues relating to geometric (satellite orbit and attitude) and electronic (antenna mis-pointing) contributions and corrections. Geophysical Doppler shift retrievals from one month of data in January 2010 and the inverted surface velocity in the Nordic Seas are then addressed and compared to other direct and indirect estimates of the upper ocean current, in particular those obtained in the ESA GlobCurrent project.

  8. Synthetic aperture double exposure digital holographic interferometry for wide angle measurement and monitoring of mechanical displacements

    Science.gov (United States)

    Kujawinska, M.; Makowski, P.; Finke, G.; Zak, J.; Józwik, M.; Kozacki, T.

    2015-08-01

    A novel approach for wide angle registration and display of double exposure digital holograms of 3D objects under static or step-wise load is presented. The registration setup concept combines digital Fourier holography with synthetic aperture (SA) technique, which is equivalent to usage of a wide angle, spherically curved detector. The coherent object wavefields extracted from a pair of acquisitions collected in the synthetic aperture double exposure digital holographic interferometry scheme (SA DEDH) are utilized as the input for two different scenarios of investigation, which include (i) numerical determination of 2D phase difference fringes representing deformation of an object and (ii) physical displaying of a 3D image resulting from interference of two object (slightly different) wavefronts registered at the SA double exposure hologram. The capture and display processes are analyzed and implemented. The applicability of both numerical and experimental approach to SA DEDH for testing engineering objects is discussed.

  9. The Application of Airborne Synthetic Aperture Radar Imagery for Studying the Archaeology of the Mayan Biosphere.

    Science.gov (United States)

    Chapman, B. D.; Blom, R.; Golden, C.; Saatchi, S.

    2008-12-01

    In March of 2004, the NASA/JPL Airborne Synthetic Aperture Radar (AIRSAR) acquired data over much of the Mayan Biosphere in Guatamala. The AIRSAR system is a fully polarimetric and interferometric synthetic aperture radar (SAR) that can both accurately measure topography at high resolution (5 m pixels) but can also measure the reflected brightness of the underlying terrain. Since AIRSAR was also a three frequency radar, a comparison can also be made as to the relative brightness at the three wavelengths of radiation. One frequency in particular, P-band, has a wavelength of almost 1 meter, and may significantly penetrate the forest canopy to the underlying surface features. The work that will be presented here will comprise the first step in the data processing - generating an accurate topographic map, and evaluation of that topographic data. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  10. Three-dimensional real-time synthetic aperture imaging using a rotating phased array transducer

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Dufait, Remi; Schoisswohl, Armin

    2002-01-01

    Current 3D real-time imaging is done either with sparse 2D arrays, or with mechanically moved phased arrays. The former results in a poor resolution and contrast due to a limited amount of elements. The latter has the disadvantage of low frame rates due to the sequential acquisition of the volume...... line-by-line and plane-by-plane. This paper describes an approach which combines mechanically moved phased array with synthetic transmit aperture imaging, resulting in high volume acquisition rates without a trade-off in image quality. The scan method uses a conventional fully populated 64 element...... phased array, which is rotated over the volume of interest. The data is acquired using coded signals and synthetic transmit aperture imaging. Only one group of elements transmits at a time. The delays are set such as to form a cylindrical wave. The back-scattered signal carries information not only from...

  11. Improved Beamforming for Lateral Oscillations in Elastography Using Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Liebgott, Hervé; Basarab, Adrian; Loizeau, Damien

    2007-01-01

    displacement estimation using images with lateral oscillations, it is necessary to reduce both the wavelength of the lateral oscillations and the width of the point spread function (PSF). This is reached in this work, by doing emit and receive beamforming using synthetic aperture data. We show......In this paper we present a beamforming technique based on synthetic aperture imaging that enables to improve the radio-frequency (RF) ultrasound images with lateral oscillations for lateral displacement estimation. As described in previous work, in order to increase the accuracy of the lateral...... that the wavelength of the lateral oscillations can be reduced by a factor 2, and the width of the PSF can be reduced by a factor radic2. We have used the images obtained by this beamforming technique for lateral displacement estimation in the field of elastography. We show that with this new approach it is possible...

  12. Focusing of airborne synthetic aperture radar data from highly nonlinear flight tracks

    OpenAIRE

    Frey, O.; Magnard, C; RÜEGG, M.; Meier, E.

    2009-01-01

    Standard focusing of data from synthetic aperture radar (SAR) assumes a straight recording track of the sensor platform. Small nonlinearities of airborne platform tracks are corrected for during a motion-compensation step while maintaining the assumption of a linear flight path. This paper describes the processing of SAR data acquired from nonlinear tracks, typical of sensors mounted on small aircraft or drones flying at low altitude. Such aircraft do not fly along straight tracks, but the tr...

  13. Texture processing of synthetic aperture radar data using second-order spatial statistics

    Science.gov (United States)

    Filho, Otto C. Rotunno; Treitz, Paul M.; Soulis, Eric D.; Howarth, Philip J.; Kouwen, Nicholas

    1996-02-01

    A method is presented for generating second-order spatial statistics (texture) from digital image data using the neighboring gray-level dependence matrix (NGLDM). Texture processing of a high-resolution airborne synthetic aperture radar image in an agricultural environment improved crop classification over the raw data. Classification of the large-number emphasis feature, based on the NGLDM (window size = 11 × 11, α = 24 and β = 1), showed a 30.5% improvement in validation accuracy over the tonal data.

  14. Computational Complexity Reduction of Synthetic-aperture Focus in Ultrasound Imaging Using Frequency-domain Reconstruction.

    Science.gov (United States)

    Moghimirad, Elahe; Mahloojifar, Ali; Mohammadzadeh Asl, Babak

    2016-05-01

    A new frequency-domain implementation of a synthetic aperture focusing technique is presented in the paper. The concept is based on synthetic aperture radar (SAR) and sonar that is a developed version of the convolution model in the frequency domain. Compared with conventional line-by-line imaging, synthetic aperture imaging has a better resolution and contrast at the cost of more computational load. To overcome this problem, point-by-point reconstruction methods have been replaced by block-processing algorithms in radar and sonar; however, these techniques are relatively unknown in medical imaging. In this paper, we extended one of these methods called wavenumber to medical ultrasound imaging using a simple model of synthetic aperture focus. The model, derived here for monostatic mode, can be generalized to multistatic as well. The method consists of 4 steps: a 2D fast Fourier transform of the data, frequency shift of the data to baseband, interpolation to convert polar coordinates to rectangular ones, and returning the data to the spatial-domain using a 2D inverse Fourier transform. We have also used chirp pulse excitation followed by matched filtering and spotlighting algorithm to compensate the effect of differences in parameters between radar and medical imaging. Computational complexities of the two methods, wavenumber and delay-and-sum (DAS), have been calculated. Field II simulated point data have been used to evaluate the results in terms of resolution and contrast. Evaluations with simulated data show that for typical phantoms, reconstruction by the wavenumber algorithm is almost 20 times faster than classical DAS while retaining the resolution. © The Author(s) 2015.

  15. 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....

  16. 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.

  17. Preliminary study of synthetic aperture tissue harmonic imaging on in-vivo data

    Science.gov (United States)

    Rasmussen, Joachim H.; Hemmsen, Martin C.; Madsen, Signe S.; Hansen, Peter M.; Nielsen, Michael B.; Jensen, Jørgen A.

    2013-03-01

    A method for synthetic aperture tissue harmonic imaging is investigated. It combines synthetic aperture sequen- tial beamforming (SASB) with tissue harmonic imaging (THI) to produce an increased and more uniform spatial resolution and improved side lobe reduction compared to conventional B-mode imaging. Synthetic aperture sequential beamforming tissue harmonic imaging (SASB-THI) was implemented on a commercially available BK 2202 Pro Focus UltraView ultrasound system and compared to dynamic receive focused tissue harmonic imag- ing (DRF-THI) in clinical scans. The scan sequence that was implemented on the UltraView system acquires both SASB-THI and DRF-THI simultaneously. Twenty-four simultaneously acquired video sequences of in-vivo abdominal SASB-THI and DRF-THI scans on 3 volunteers of 4 different sections of liver and kidney tissues were created. Videos of the in-vivo scans were presented in double blinded studies to two radiologists for image quality performance scoring. Limitations to the systems transmit stage prevented user defined transmit apodization to be applied. Field II simulations showed that side lobes in SASB could be improved by using Hanning transmit apodization. Results from the image quality study show, that in the current configuration on the UltraView system, where no transmit apodization was applied, SASB-THI and DRF-THI produced equally good images. It is expected that given the use of transmit apodization, SASB-THI could be further improved.

  18. Using Synthetic Aperture Radar Wind Measurements to support Offshore Wind Parks

    Science.gov (United States)

    Schneiderhan, T.; Lehner, S.; Horstmann, J.; Koch, W.; Schulz-Stellenfleth, J.

    2003-04-01

    In all countries with shallow coastal waters and a strong mean wind speed offshore wind parks are planned and built. The fast development of wind energy production in Europe led to an installation of more than 18 000 MW by the end of the year 2001. The installed offshore power up to date is about 100 MW. In the near future many projects for wind farms with an output of more than 5000 MW are planned. Some of these projects are already under construction. Offshore wind parks are showing a big potential for future energy production and solving ecological problems in reducing the CO^2 output. The construction and maintenance of offshore wind parks has to face the tough environmental conditions of the open sea resulting extensive maintenance and money. Therefore reliable forecast in particular of the wind and the ocean wave fields is essential. Space borne SAR data as acquired by the ERS satellites or the new ENVISAT satellite, launched in March 2002, provide two dimensional wind fields with a sub-kilometre resolution and a coverage of up to 500 by 500 km in the wide swath mode. They are thus ideally suited to investigate the spatial fine structure like e.g. turbulence in the wake of wind parks, which is an important factor in the optimal siting of wind farms. Due to their high coverage and resolution SAR data can provide information on the impact of the single turbines on the wind field experienced by the neighbouring turbines as well as the effect of the whole wind park on the local climate. This study shows the potential of two dimensional high resolution wind fields measured with space borne synthetic aperture radar to support the construction and operation of wind farms. The data can be used to minimize fatigue loading due to wind gusts as well as to provide short term power forecasts in order to optimise the power output. Examples of wind fields around the already existing offshore wind parks Utgrunden (South of Sweden) and Horns Rev (West of Denmark) and the

  19. Coseismic Deformation of Chi-Chi Earthquake as Detected by Differential Synthetic Aperture Radar Interferometry and GPS Data

    Directory of Open Access Journals (Sweden)

    Chia-Sheng Hsieh Tian-Yuan Shih

    2006-01-01

    Full Text Available A rupture in the Chelungpu fault caused an Mw 7.6 earthquake on 21 September 1999 near Chi-Chi in central Taiwan. This earthquake was the most destructive experienced in Taiwan for the past century along this fault. In this study, we examined the earthquake-induced surface deformation pattern using differential synthetic aperture radar interferometry (D-InSAR combined with global positioning system (GPS data regarding the footwall of the Chelungpu fault. Six synthetic aperture radar (SAR scenes, approximately 100 × 100 km each, recorded by the European Remote Sensing Satellite 2 (ERS-2, spanning the rupture area, were selected for study. The data were used to generate a high-resolution, wide-area map of displacements in flat or semi-flat areas. Interferograms show radar line contours indicating line-of-sight (LOS changes corresponding to surface displacements caused by earthquake ruptures. These results were compared to synthetic interferograms generated from GPS data. Displacements shown by GPS data were interpolated onto wide-area maps and transformed to coincide with the radar LOS direction. The resulting coseismic displacement contour map showed a lobed pattern consistent with the precise GPSbased displacement field. Highly accurate vertical displacement was determined using D-InSAR data using the coordinate transform method, while GPS data was effective in showing the horizontal component. Thus, this study confirmed the effectiveness of the D-InSAR method for determining the coseismic deformation caused by the Chi-Chi earthquake at the footwall of the Chelungpu fault.

  20. Edge detection for optical synthetic aperture based on deep neural network

    Science.gov (United States)

    Tan, Wenjie; Hui, Mei; Liu, Ming; Kong, Lingqin; Dong, Liquan; Zhao, Yuejin

    2017-09-01

    Synthetic aperture optics systems can meet the demands of the next-generation space telescopes being lighter, larger and foldable. However, the boundaries of segmented aperture systems are much more complex than that of the whole aperture. More edge regions mean more imaging edge pixels, which are often mixed and discretized. In order to achieve high-resolution imaging, it is necessary to identify the gaps between the sub-apertures and the edges of the projected fringes. In this work, we introduced the algorithm of Deep Neural Network into the edge detection of optical synthetic aperture imaging. According to the detection needs, we constructed image sets by experiments and simulations. Based on MatConvNet, a toolbox of MATLAB, we ran the neural network, trained it on training image set and tested its performance on validation set. The training was stopped when the test error on validation set stopped declining. As an input image is given, each intra-neighbor area around the pixel is taken into the network, and scanned pixel by pixel with the trained multi-hidden layers. The network outputs make a judgment on whether the center of the input block is on edge of fringes. We experimented with various pre-processing and post-processing techniques to reveal their influence on edge detection performance. Compared with the traditional algorithms or their improvements, our method makes decision on a much larger intra-neighbor, and is more global and comprehensive. Experiments on more than 2,000 images are also given to prove that our method outperforms classical algorithms in optical images-based edge detection.

  1. Graphene-based liquid-crystal microlens arrays for synthetic-aperture imaging

    Science.gov (United States)

    Wu, Yong; Hu, Wei; Tong, Qing; Lei, Yu; Xin, Zhaowei; Wei, Dong; Zhang, Xinyu; Liao, Jing; Wang, Haiwei; Xie, Changsheng

    2017-09-01

    In this paper, a new kind of liquid-crystal microlens array with graphene electrodes controlled electrically are designed and fabricated successfully. The graphene-based liquid-crystal microlens arrays (GLCMAs) exhibit excellent beam focusing performances in both the visible and near infrared (NIR) wavelength regions and also synthetic aperture imaging function. The graphene films used to fabricate the electrodes of the GLCMAs are grown by chemical vapor deposition over copper foils, demonstrating several characters of low sheet resistance and high transmittance in both wavelength ranges above. The key processes for shaping the GLCMAs include: transferring graphene films from copper foils to wafers selected, conventional UV-photolithography, ICP etching, and liquid-crystal encapsulation. Through performing common optical measurements, the point spread functions of incident lasers with different wavelength, such as red lasers of ∼600 nm, green lasers of ∼532 nm, and NIR lasers of ∼980 nm, have been obtained. Several key parameters including focal spots size, average normalized light intensity, focal length, average deviation rate and contrast ratio have been acquired and analyzed. A particular synthetic-aperture imaging based on the GLCMA is realized so as to certify a fact that a single target pattern can be constructed effectively based on some sub-aperture patterns with several tens or hundreds of micrometer scale, and thus highlight a way to fast process partial or small-zoned patterns for enhancing the detection efficiency of special targets.

  2. Waves in the Southern Ocean as observed by Sentinel1 synthetic aperture radars

    Science.gov (United States)

    Stopa, Justin E.; Sutherland, Peter; Ardhuin, Fabrice

    2017-04-01

    Sea ice plays an important role in the Earth system by regulating air-sea fluxes and moderating the global temperatures. These fluxes can be enhanced by the presence of waves, especially through the breaking of ice into floes which depends on the waves propagating across the ice. The paucity of adequate in-situ wave observations in ice covered seas limits our ability to understand wave-ice interactions. Synthetic Aperture Radar (SAR) imagery over sea ice appears consistent with a dominant modulation of the radar backscatter by velocity bunching (Ardhuin et al. GRL 2015). Because the presence of sea ice generally removes the blurring effects of short wave components, the SAR transformation is more simple than in the open ocean. This property makes it possible to retrieve phase-resolved maps of wave orbital velocities and wave spectra (Ardhuin et al., 2017 RSE). We can thus now use SAR imagery for scientific applications to wave-ice interactions. With the all-weather capabilities and extensive space-time coverage, the Sentinel1 constellation composed of two satellites (S1A & S1B) both equipped with SARs provides the opportunity to extract valuable wave observations in polar regions. Through the high resolution acquisition modes of S1A and S1B which cover the Southern Ocean in 20x20 km images with 4 m spatial resolution we are able to extract an large sample of wave observations. We analyzed more than 35,000 images in the Southern Ocean. Nearly 28% of the images contain wave features and 6% of the images contain well-imaged single wave systems (>2000 wave spectra), with a narrow directional distribution. This dataset of more than 2000 wave spectra is unique in the fact we cover the entire Southern Ocean sea ice with an unprecedented amount of observations. These observations support the idea that the attenuation of waves with periods longer than 10 s is dominated by dissipation processes with a limited effect of scattering. Dissipation rates are estimated from pairs

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

    Energy Technology Data Exchange (ETDEWEB)

    Di Martire, Diego, E-mail: diego.dimartire@unina.it [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy); Novellino, Alessandro, E-mail: alessandro.novellino@unina.it [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy); Ramondini, Massimo, E-mail: ramondin@unina.it [Department of Civil, Architectural and Environmental Engineering, Federico II University of Naples, via Claudio 21, 80125 Naples (Italy); Calcaterra, Domenico, E-mail: domenico.calcaterra@unina.it [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy)

    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. - Highlights: • DInSAR confirmed to be a reliable tool in monitoring slow-moving landslides. • Integration with traditional monitoring systems is crucial for DInSAR application. • DInSAR data can be used for the natural risk mitigation related to landslides.

  4. Preliminary determination of geothermal working area based on Thermal Infrared and Synthetic Aperture Radar (SAR) remote sensing

    Science.gov (United States)

    Agoes Nugroho, Indra; Kurniawahidayati, Beta; Syahputra Mulyana, Reza; Saepuloh, Asep

    2017-12-01

    Remote sensing is one of the methods for geothermal exploration. This method can be used to map the geological structures, manifestations, and predict the geothermal potential area. The results from remote sensing were used as guidance for the next step exploration. Analysis of target in remote sensing is an efficient method to delineate geothermal surface manifestation without direct contact to the object. The study took a place in District Merangin, Jambi Province, Indonesia. The area was selected due to existing of Merangin volcanic complex composed by Mounts Sumbing and Hulunilo with surface geothermal manifestations presented by hot springs and hot pools. The location of surface manifestations could be related with local and regional structures of Great Sumatra Fault. The methods used in this study were included identification of volcanic products, lineament extraction, and lineament density quantification. The objective of this study is to delineate the potential zones for sitting the geothermal working site based on Thermal Infrared and Synthetic Aperture Radar (SAR) sensors. The lineament-related to geological structures, was aimed for high lineament density, is using ALOS - PALSAR (Advanced Land Observing Satellite - The Phased Array type L-band Synthetic Aperture Radar) level 1.1. The Normalized Difference Vegetation Index (NDVI) analysis was used to predict the vegetation condition using Landsat 8 OLI-TIRS (The Operational Land Imager – Thermal Infrared Sensor). The brightness temperature was extracted from TIR band to estimate the surface temperature. Geothermal working area identified based on index overlay method from extracted parameter of remote sensing data was located at the western part of study area (Graho Nyabu area). This location was identified because of the existence of high surface temperature about 30°C, high lineament density about 4 - 4.5 km/km2 and low NDVI values less than 0.3.

  5. Attitude-error compensation for airborne down-looking synthetic-aperture imaging lidar

    Science.gov (United States)

    Li, Guang-yuan; Sun, Jian-feng; Zhou, Yu; Lu, Zhi-yong; Zhang, Guo; Cai, Guang-yu; Liu, Li-ren

    2017-11-01

    Target-coordinate transformation in the lidar spot of the down-looking synthetic-aperture imaging lidar (SAIL) was performed, and the attitude errors were deduced in the process of imaging, according to the principle of the airborne down-looking SAIL. The influence of the attitude errors on the imaging quality was analyzed theoretically. A compensation method for the attitude errors was proposed and theoretically verified. An airborne down-looking SAIL experiment was performed and yielded the same results. A point-by-point error-compensation method for solving the azimuthal-direction space-dependent attitude errors was also proposed.

  6. 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.

  7. In-Vivo Synthetic Aperture and Plane Wave High Frame Rate Cardiac Imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Jensen, Jonas; Brandt, Andreas Hjelm

    2014-01-01

    A comparison of synthetic aperture imaging using spherical and plane waves with low number of emission events is presented. For both wave types, a 90 degree sector is insonified using 15 emission events giving a frame rate of 200 frames per second. Field II simulations of point targets show simil.......43 for spherical and 0.70 for plane waves. All measures are well within FDA limits for cardiac imaging. In-vivo images of the heart of a healthy 28-year old volunteer are shown....

  8. Non-linear Imaging using an Experimental Synthetic Aperture Real Time Ultrasound Scanner

    DEFF Research Database (Denmark)

    Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt

    2011-01-01

    This paper presents the first non-linear B-mode image of a wire phantom using pulse inversion attained via an experimental synthetic aperture real-time ultrasound scanner (SARUS). The purpose of this study is to implement and validate non-linear imaging on SARUS for the further development of new...... non-linear techniques. This study presents non-linear and linear B-mode images attained via SARUS and an existing ultrasound system as well as a Field II simulation. The non-linear image shows an improved spatial resolution and lower full width half max and -20 dB resolution values compared to linear...

  9. 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.

  10. A novel synthetic aperture technique for breast tomography with toroidal arrays

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lianjie [Los Alamos National Laboratory; Simonetti, Francesco [IMPERIAL COLLEGE

    2009-01-01

    Ultrasound is commonly used as an adjunct to mammography for diagnostic evaluation of suspicions arising from breast cancer screening. As an alternative to conventional sonography that uses hand-held transducers, toroidal array probes that encircle the breast immersed in a water bath have been investigated for ultrasound tomography. This paper introduces a new method for three-dimensional synthetic aperture diffraction tomography that maximizes the resolution in the scanning direction and provides quantitative reconstructions of the acoustic properties of the object. The method is validated by means of numerical simulations.

  11. Correction of motion measurement errors beyond the range resolution of a synthetic aperture radar

    Science.gov (United States)

    Doerry, Armin W [Albuquerque, NM; Heard, Freddie E [Albuquerque, NM; Cordaro, J Thomas [Albuquerque, NM

    2008-06-24

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  12. Noise and speckle reduction in synthetic aperture radar imagery by nonparametric Wiener filtering.

    Science.gov (United States)

    Caprari, R S; Goh, A S; Moffatt, E K

    2000-12-10

    We present a Wiener filter that is especially suitable for speckle and noise reduction in multilook synthetic aperture radar (SAR) imagery. The proposed filter is nonparametric, not being based on parametrized analytical models of signal statistics. Instead, the Wiener-Hopf equation is expressed entirely in terms of observed signal statistics, with no reference to the possibly unobservable pure signal and noise. This Wiener filter is simple in concept and implementation, exactly minimum mean-square error, and directly applicable to signal-dependent and multiplicative noise. We demonstrate the filtering of a genuine two-look SAR image and show how a nonnegatively constrained version of the filter substantially reduces ringing.

  13. Improved eigensubspace-based approach for radio frequency interference filtering of synthetic aperture radar images

    Science.gov (United States)

    Zhou, Chunhui; Li, Fei; Li, Ning; Zheng, Huifang; Wang, Robert; Wang, Xiangyu

    2017-04-01

    The radio frequency interference (RFI) has an adverse effect on the useful signals, which can degrade the image quality seriously. An improved eigensubspace-based approach for RFI filtering of synthetic aperture radar images is developed. In the preprocessing stage of the proposed approach, the data sets that need subsequent processing can be selected in both frequency and time domain. Then, the data can be processed by the traditional eigensubspace-based approach. Compared with the traditional eigensubspace-based approach, our approach can work more efficiently and effectively.

  14. 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.

  15. Computer processing of SAR L-band imagery. [Synthetic Aperture Radar for ice mapping

    Science.gov (United States)

    Bryan, M. L.; Stromberg, W. D.; Farr, T. G.

    1977-01-01

    The described work in the areas of hydrology and polar ice defines possible uses of automatic picture processing of uncalibrated radar images. The data used in the study were collected with the aid of an L-band synthetic aperture radar mounted in the NASA CV-990 aircraft. The radar was operated at approximately 30,000 feet altitude. One study area used was located in the Beaufort Sea and contained sea ice. The other study area contained lakes on the Alaskan North Slope. The reported investigations demonstrate that certain types of features can be efficiently studied by using simple automatic picture processing techniques applied to uncalibrated radar data.

  16. 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.

  17. Discussion on Application of Polarimetric Synthetic Aperture Radar in Marine Surveillance

    Directory of Open Access Journals (Sweden)

    Zhang Jie

    2016-12-01

    Full Text Available Synthetic Aperture Radar (SAR, an important earth observation sensor, has been used in a wide range of applications for land and marine surveillance. Polarimetric SAR (PolSAR can obtain abundant scattering information of a target to improve the ability of target detection, classification, and quantitative inversion. In this paper, the important role of PolSAR in ocean monitoring is discussed with factors such as sea ice, ships, oil spill, waves, internal waves, and seabed topography. Moreover, the future development direction of PolSAR is put forward to get an inspiration for further research of PolSAR in marine surveillance applications.

  18. Synthetic Aperture Focusing for a Single Element Transducer undergoing Helix Motion

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt

    2011-01-01

    This paper describes the application of 3D synthetic aperture focusing (SAF) to a single element trans-rectal ultrasound transducer. The transducer samples a 3D volume by simultaneous rotation and translation giving a helix motion. Two different 3D SAF methods are investigated, a direct and a two...... and a complex phantom containing wires in azimuth and elevation. The simple wire phantom shows the same results as that found through simulation. The complex phantom shows simultaneous focusing in azimuth and elevation for the wire scatterers. Considerations on processing requirements for both 3D SAF methods...

  19. 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...

  20. 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

  1. Preliminary study of synthetic aperture tissue harmonic imaging on in-vivo data

    DEFF Research Database (Denmark)

    Rasmussen, Joachim Hee; Hemmsen, Martin Christian; Sloth Madsen, Signe

    2013-01-01

    that was implemented on the UltraView system acquires both SASB-THI and DRF-THI simultaneously. Twenty-four simultaneously acquired video sequences of in-vivo abdominal SASB-THI and DRF-THI scans on 3 volunteers of 4 different sections of liver and kidney tissues were created. Videos of the in-vivo scans were......-mode imaging. Synthetic aperture sequential beamforming tissue harmonic imaging (SASB-THI) was implemented on a commercially available BK 2202 Pro Focus UltraView ultrasound system and compared to dynamic receive focused tissue harmonic imaging (DRF-THI) in clinical scans. The scan sequence...

  2. Microwave and Millimeter Wave Imaging Using Synthetic Aperture Focusing and Holographical Techniques

    Science.gov (United States)

    Case, Joseph Tobias

    2005-01-01

    Microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods have shown great potential for determining material composition in composite structures, determining material thickness or debond thickness between two layers, and determining the location and size of flaws, defects, and anomalies. The same testing methods have also shown great potential to produce relatively high-resolution images of voids inside Spray On Foam Insulation (SOFI) test panels using real focused methods employing lens antennas. An alternative to real focusing methods are synthetic focusing methods. The essence of synthetic focusing is to match the phase of the scattered signal to measured points spaced regularly on a plane. Many variations of synthetic focusing methods have already been developed for radars, ultrasonic testing applications, and microwave concealed weapon detection. Two synthetic focusing methods were investigated; namely, a) frequency-domain synthetic aperture focusing technique (FDSAFT), and b) wide-band microwave holography. These methods were applied towards materials whose defects were of low dielectric contrast like air void in SOFI. It is important to note that this investigation used relatively low frequencies from 8.2 GHz to 26.5 GHz that are not conducive for direct imaging of the SOFI. The ultimate goal of this work has been to demonstrate the capability of these methods before they are applied to much higher frequencies such as the millimeter wave frequency spectrum (e.g., 30-300 GHz).

  3. 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.

  4. On the retrieval of significant wave heights from spaceborne Synthetic Aperture Radar using the Max-Planck Institut algorithm.

    Science.gov (United States)

    Violante-Carvalho, Nelson

    2005-12-01

    Synthetic Aperture Radar (SAR) onboard satellites is the only source of directional wave spectra with continuous and global coverage. Millions of SAR Wave Mode (SWM) imagettes have been acquired since the launch in the early 1990's of the first European Remote Sensing Satellite ERS-1 and its successors ERS-2 and ENVISAT, which has opened up many possibilities specially for wave data assimilation purposes. The main aim of data assimilation is to improve the forecasting introducing available observations into the modeling procedures in order to minimize the differences between model estimates and measurements. However there are limitations in the retrieval of the directional spectrum from SAR images due to nonlinearities in the mapping mechanism. The Max-Planck Institut (MPI) scheme, the first proposed and most widely used algorithm to retrieve directional wave spectra from SAR images, is employed to compare significant wave heights retrieved from ERS-1 SAR against buoy measurements and against the WAM wave model. It is shown that for periods shorter than 12 seconds the WAM model performs better than the MPI, despite the fact that the model is used as first guess to the MPI method, that is the retrieval is deteriorating the first guess. For periods longer than 12 seconds, the part of the spectrum that is directly measured by SAR, the performance of the MPI scheme is at least as good as the WAM model.

  5. Exploiting the sparsity of edge information in synthetic aperture radar imagery for speckle reduction

    Science.gov (United States)

    Scarnati, Theresa; Zelnio, Edmund; Paulson, Christopher

    2017-04-01

    Synthetic aperture radar (SAR) images are corrupted with speckle noise, which manifests as a multiplicative gamma noise and reduces the contrast in imagery, making detection and classifi- cation using SAR images a difficult task. Many speckle reduction techniques aim to reduce this noise without including available prior knowledge about the speckle and the scene contents. In this investigation, we develop a new technique for speckle reduction which incorporates both the statistical model of speckle and the a priori knowledge about the sparsity of edges present in the scene. Using the proposed technique, we despeckle a synthetic image, a SAR image from the MSTAR data set and a SAR image from the Gotcha data set. Our results show that, with our method, we are able to visually improve the quality of SAR images. We show quantitatively that we are able to reduce speckle in homogeneous areas beyond comparable methods, while maintaining edge and target intensity information.

  6. High resolution three-dimensional robotic synthetic tracked aperture ultrasound imaging: feasibility study

    Science.gov (United States)

    Zhang, Haichong K.; Fang, Ting Yun; Finocchi, Rodolfo; Boctor, Emad M.

    2017-03-01

    Three dimensional (3D) ultrasound imaging is becoming a standard mode for medical ultrasound diagnoses. Conventional 3D ultrasound imaging is mostly scanned either by using a two dimensional matrix array or by motorizing a one dimensional array in the elevation direction. However, the former system is not widely assessable due to its cost, and the latter one has limited resolution and field-of-view in the elevation axis. Here, we propose a 3D ultrasound imaging system based on the synthetic tracked aperture approach, in which a robotic arm is used to provide accurate tracking and motion. While the ultrasound probe is moved by a robotic arm, each probe position is tracked and can be used to reconstruct a wider field-of-view as there are no physical barriers that restrict the elevational scanning. At the same time, synthetic aperture beamforming provides a better resolution in the elevation axis. To synthesize the elevational information, the single focal point is regarded as the virtual element, and forward and backward delay-andsum are applied to the radio-frequency (RF) data collected through the volume. The concept is experimentally validated using a general ultrasound phantom, and the elevational resolution improvement of 2.54 and 2.13 times was measured at the target depths of 20 mm and 110 mm, respectively.

  7. Single Carrier with Frequency Domain Equalization for Synthetic Aperture Underwater Acoustic Communications.

    Science.gov (United States)

    He, Chengbing; Xi, Rui; Wang, Han; Jing, Lianyou; Shi, Wentao; Zhang, Qunfei

    2017-07-06

    Phase-coherent underwater acoustic (UWA) communication systems typically employ multiple hydrophones in the receiver to achieve spatial diversity gain. However, small underwater platforms can only carry a single transducer which can not provide spatial diversity gain. In this paper, we propose single-carrier with frequency domain equalization (SC-FDE) for phase-coherent synthetic aperture acoustic communications in which a virtual array is generated by the relative motion between the transmitter and the receiver. This paper presents synthetic aperture acoustic communication results using SC-FDE through data collected during a lake experiment in January 2016. The performance of two receiver algorithms is analyzed and compared, including the frequency domain equalizer (FDE) and the hybrid time frequency domain equalizer (HTFDE). The distances between the transmitter and the receiver in the experiment were about 5 km. The bit error rate (BER) and output signal-to-noise ratio (SNR) performances with different receiver elements and transmission numbers were presented. After combining multiple transmissions, error-free reception using a convolution code with a data rate of 8 kbps was demonstrated.

  8. Review and discussion of the development of synthetic aperture focusing technique for ultrasonic testing (SAFT-UT)

    Energy Technology Data Exchange (ETDEWEB)

    Busse, L J; Collins, H D; Doctor, S R

    1984-03-01

    The development and capabilities of synthetic aperture focusing techniques for ultrasonic testing (SAFT-UT) are presented. The purpose of SAFT-UT is to produce high-resolution images of the interior of opaque objects. The goal of this work is to develop and implement methods which can be used to detect and to quantify the extent of defects and cracks in critical components of nuclear reactors (pressure vessels, primary piping systems, and nozzles). This report places particular emphasis upon the practical experimental results that have been obtained using SAFT-UT as well as the theoretical background that underlies synthetic aperture focusing. A discussion regarding high-speed and real-time implementations of two- and three-dimensional synthetic aperture focusing is also presented.

  9. Alternative synthetic aperture radar (SAR) modalities using a 1D dynamic metasurface antenna

    Science.gov (United States)

    Boyarsky, Michael; Sleasman, Timothy; Pulido-Mancera, Laura; Imani, Mohammadreza F.; Reynolds, Matthew S.; Smith, David R.

    2017-05-01

    Synthetic aperture radar (SAR) systems conventionally rely on mechanically-actuated reflector dishes or large phased arrays for generating steerable directive beams. While these systems have yielded high-resolution images, the hardware suffers from considerable weight, high cost, substantial power consumption, and moving parts. Since these disadvantages are particularly relevant in airborne and spaceborne systems, a flat, lightweight, and low-cost solution is a sought-after goal. Dynamic metasurface antennas have emerged as a recent technology for generating waveforms with desired characteristics. Metasurface antennas consist of an electrically-large waveguide loaded with numerous subwavelength radiators which selectively leak energy from a guided wave into free space to form various radiation patterns. By tuning each radiating element, we can modulate the aperture's overall radiation pattern to generate steered directive beams, without moving parts or phase shifters. Furthermore, by using established manufacturing methods, these apertures can be made to be lightweight, low-cost, and planar, while maintaining high performance. In addition to their hardware benefits, dynamic metasurfaces can leverage their dexterity and high switching speeds to enable alternative SAR modalities for improved performance. In this work, we briefly discuss how dynamic metasurfaces can conduct existing SAR modalities with similar performance as conventional systems from a significantly simpler hardware platform. We will also describe two additional modalities which may achieve improved performance as compared to traditional modalities. These modalities, enhanced resolution stripmap and diverse pattern stripmap, offer the ability to circumvent the trade-off between resolution and region-of-interest size that exists within stripmap and spotlight. Imaging results with a simulated dynamic metasurface verify the benefits of these modalities and a discussion of implementation considerations

  10. Combined synthetic aperture focusing technique and three-dimensional deconvolution for resolution enhancement in photoacoustic microscopy

    Science.gov (United States)

    Cai, De; Li, Zhongfei; Li, Yao; Guo, Zhendong; Chen, Sung-Liang

    2017-03-01

    Acoustic-resolution photoacoustic microscopy (ARPAM) is a promising tool for deep imaging of biological tissues. Synthetic aperture focusing technique (SAFT) can improve the degraded lateral resolution in the out-of-focus region of ARPAM when using a high numerical aperture acoustic transducer. We previously reported a three-dimensional (3D) deconvolution technique to improve both lateral and axial resolutions in the focus region of ARPAM. In this work, we extended resolution enhancement of ARPAM to the out-of-focus region based on two dimensional SAFT combined with the 3D deconvolution (SAFT+Deconv). In both the focus and out-of-focus regions, depth-independent lateral and axial resolution after SAFT ensures a depth-independent point spread function for 3D deconvolution algorithm. In an extended depth of focus (DOF) of 2 mm, SAFT+Deconv ARPAM improves the -6 dB lateral resolutions from 65-700 μm to 20-29 μm, and the -6 dB axial resolutions from 35-42 μm to 12-19 μm. The signal-to-noise ratio is also increased by 6-30 dB. The enhanced resolution in extended DOF by SAFT+Deconv ARPAM may enable important applications in biomedical photoacoustic imaging.

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

    Directory of Open Access Journals (Sweden)

    S. Chiu

    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.

  12. Precise Time-of-Flight Calculation For 3-D Synthetic Aperture Focusing

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2009-01-01

    Conventional linear arrays can be used for 3D ultrasound imaging, by moving the array in the elevation direction and stacking the planes in a volume. The point spread function (PSF) is larger in the elevation plane, as the aperture is smaller and has a fixed elevation focus. Resolution improvements...... in elevation can be achieved by applying synthetic aperture (SA) focusing to the beamformed in-plane RF-data. The proposed method uses a virtual source (VS) placed at the elevation focus for postbeamforming. This has previously been done in two steps, in plane focusing followed by SA post-focusing in elevation......, because of a lack of a simple expression for the exact time of flight (ToF). This paper presents a new method for calculating the ToF for a 3D case in a single step using a linear array. This method is more flexible than the previously proposed method and is able to beamform a fewer number of points much...

  13. Precise Time-of-Flight Calculation For 3D Synthetic Aperture Focusing

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2007-01-01

    Conventional linear arrays can be used for 3D ultrasound imaging, by moving the array in the elevation direction and stacking the planes in a volume. The point spread function (PSF) is larger in the elevation plane, as the aperture is smaller and has a fixed elevation focus. Resolution improvements...... in elevation can be achieved by applying synthetic aperture (SA) focusing to the beamformed in-plane RF-data. The method uses a virtual source (VS) placed at the elevation focus for post-beamforming. This has previously been done in two steps, in plane focusing followed by SA post-focusing in elevation......, because of a lack of a simple expression for the exact time of flight (ToF). This paper presents a new method for calculating the ToF for a 3D case in a single step using a spherical defocused emission from a linear array. The method is evaluated using both simulated data obtained by Field II and phantom...

  14. PAU-SA: A Synthetic Aperture Interferometric Radiometer Test Bed for Potential Improvements in Future Missions

    Directory of Open Access Journals (Sweden)

    Merce Vall-llosera

    2012-06-01

    Full Text Available The Soil Moisture and Ocean Salinity (SMOS mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA. Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS. The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS, the Precipitation and All-weather Temperature and Humidity (PATH and the Geostationary Interferometric Microwave Sounder (GIMS. Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS’s design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions.

  15. PAU-SA: A Synthetic Aperture Interferometric Radiometer Test Bed for Potential Improvements in Future Missions

    Science.gov (United States)

    Ramos-Perez, Isaac; Camps, Adriano; Bosch-Lluis, Xavi; Rodriguez-Alvarez, Nereida; Valencia-Domènech, Enric; Park, Hyuk; Forte, Giuseppe; Vall-llosera, Merce

    2012-01-01

    The Soil Moisture and Ocean Salinity (SMOS) mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA). Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA) instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS), the Precipitation and All-weather Temperature and Humidity (PATH) and the Geostationary Interferometric Microwave Sounder (GIMS). Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS's design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions. PMID:22969371

  16. 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.

  17. Lq regularization-based unobserved baselines' data estimation method for tomographic synthetic aperture radar inversion

    Science.gov (United States)

    Bi, Hui; Zhang, Bingchen; Hong, Wen

    2016-07-01

    The elevation image quality of tomographic synthetic aperture radar (TomoSAR) data depends mainly on the elevation aperture size, number of baselines, and baseline distribution. In TomoSAR, due to the restricted number of baselines with irregular distributions, the elevation imaging quality is always unacceptable using the conventional spectral analysis approach. Therefore, for a given limited number of irregular baselines, the completion of data for the unobserved virtual uniform baseline distribution should be addressed to improve the spectral analysis-based TomoSAR reconstruction quality. We propose an Lq(0TomoSAR, which uses the geometric imaging relationship between the observed and unobserved baseline distributions. In the proposed method, we first estimate the transformation matrix between the acquisitions and the data of virtual uniform baseline distribution by solving an optimization problem, before calculating the data for virtual baseline distribution based on the acquisitions and the transformation matrix. Finally, the elevation reflectivity function is recovered using the spectral analysis method based on the estimated data. Compared with the reconstructed results only based on the limited irregular acquisitions, the image recovered using the dataset with a virtual uniform baseline distribution can improve the elevation image quality in an efficient manner.

  18. Waveform Retracking and Emulation Experiment Analysis of Synthetic Aperture Radar Altimeter

    Directory of Open Access Journals (Sweden)

    ZHAI Zhenhe

    2017-02-01

    Full Text Available Based on the synthetic aperture radar(SAR convolution model, the convolution computation formula about the derivative of three parameters of time migration, rise time and amplitude are deduced. The SAR waveform retracking is completed using numerical integration and Fourier transform. Besides, the echo waveform under SAR model is generated using the simulation orbit, troposphere, ionosphere and tide model. The comparison shows that the shape of echo waveform under SAR model is the same as that of CryoSat-2 1 Hz SAR. The experiments show that the accuracy of SAR altimeter retracking is about 5 cm under the 20 Hz data(about 350 m resolution, which are improved compared with that of the traditional model.

  19. Feature discrimination and detection probability in synthetic aperture radar imaging system

    Science.gov (United States)

    Lipes, R. G.; Butman, S. A.

    1977-01-01

    Images obtained using synthetic aperture radar (SAR) systems can only represent the intensities of resolution cells in the scene of interest probabilistically since radar receiver noise and Rayleigh scattering of the transmitted radiation are always present. Consequently, when features to be identified differ only by their contribution to the mean power of the radar return, discrimination can be treated by detection theory. In this paper, we develop a 'sufficient statistic' for discriminating between competing features and compare it with some suboptimal methods frequently used. Discrimination is measured by probability of detection error and depends on number of samples or 'looks', signal-to-noise ratio (SNR), and ratio of mean power returns from the competing features. Our results show discrimination and image quality rapidly saturate with SNR (very small improvement for SNR not less than 10 dB) but continue to improve with increasing number of looks.

  20. Two-Stage Multi-Task Representation Learning for Synthetic Aperture Radar (SAR) Target Images Classification.

    Science.gov (United States)

    Zhang, Xinzheng; Wang, Yijian; Tan, Zhiying; Li, Dong; Liu, Shujun; Wang, Tao; Li, Yongming

    2017-11-01

    In this paper, we propose a two-stage multi-task learning representation method for the classification of synthetic aperture radar (SAR) target images. The first stage of the proposed approach uses multi-features joint sparse representation learning, modeled as a ℓ 2 , 1 -norm regularized multi-task sparse learning problem, to find an effective subset of training samples. Then, a new dictionary is constructed based on the training subset. The second stage of the method is to perform target images classification based on the new dictionary, utilizing multi-task collaborative representation. The proposed algorithm not only exploits the discrimination ability of multiple features but also greatly reduces the interference of atoms that are irrelevant to the test sample, thus effectively improving classification performance. Conducted with the Moving and Stationary Target Acquisition and Recognition (MSTAR) public SAR database, experimental results show that the proposed approach is effective and superior to many state-of-the-art methods.

  1. A Vector Flow Imaging Method for Portable Ultrasound Using Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    di Ianni, Tommaso; Villagómez Hoyos, Carlos Armando; Ewertsen, Caroline

    2017-01-01

    for the velocity estimation along the lateral and axial directions using a phase-shift estimator. The performance of the method was investigated with constant flow measurements in a flow rig system using the SARUS scanner and a 4.1-MHz linear array. A sequence was designed with interleaved B-mode and flow...... emissions to obtain continuous data acquisition. A parametric study was carried out to evaluate the effect of critical parameters. The vessel was placed at depths from 20 to 40 mm, with beam-to-flow angles of 65°, 75°, and 90°. For the lateral velocities at 20 mm, a bias between -5% and -6.2% was obtained......This paper presents a vector flow imaging method for the integration of quantitative blood flow imaging in portable ultrasound systems. The method combines directional transverse oscillation (TO) and synthetic aperture sequential beamforming to yield continuous velocity estimation in the whole...

  2. Synthetic aperture flow angle estimation on in-vivo data from the carotid artery

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2005-01-01

    11 transmitting elements. Data from 8 transmissions with each 64 receiving elements are beamformed and coherently summed to create high resolution lines at different angles for a set of points within the region of flow. The pulse repetition frequency was set to 10 kHz. The direction of flow...... determined flow angle. The standard deviation of these estimates was below 2.7◦. Full color flow maps from different parts of the cardiac cycle are presented, including vector arrows indicating both estimated flow direction and velocity magnitude.......In conventional ultrasound velocity estimation systems only the velocity projected onto the direction of the steered ultrasound beam is found. It has previously been shown how true blood flow velocity magnitudes can be found using synthetic transmit aperture imaging. The method is based...

  3. 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

    It is widely recognized that Synthetic Aperture Radar (SAR) data are a very valuable source of information for the modeling of the interactions between the land surface and the atmosphere. During the last couple of decades, most of the research on the use of SAR data in hydrologic applications has...... 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...... a combination of remote sensing anti land surface modeling. Spatially distributed and multitemporal SAR-based soil moisture maps are the basis of the study. The surface soil moisture values are used in a parameter estimation procedure basest on the Extended Kalman Filter equations. In fact, the land surface...

  4. Current Development in Airborne Repeat-pass Interferometric Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Zhong Xue-lian

    2013-09-01

    Full Text Available Due to its agility, flexibility and accuracy, airborne repeat-pass Interferometric Synthetic Aperture Radar (InSAR is capable of overcoming the disadvantages of long revisit time and low resolution in space-borne SAR interferometry, and play an irreplaceable role in monitoring the deformation of landslides, volcanoes, earthquakes, etc. In this paper, the history and status in the world wide about the technology of airborne repeat-pass SAR interferometry are reviewed detailedly. Then after the accuracy of this technology is analyzed, its key problems in practice are presented, and the related researches in this field are also introduced comprehensively. The development trend and the prospect of this technology are also described in this paper. Finally, it is pointed that several problems still need to be studied further for accurate parameter inversion.

  5. Target-adaptive polarimetric synthetic aperture radar target discrimination using maximum average correlation height filters.

    Science.gov (United States)

    Sadjadi, Firooz A; Mahalanobis, Abhijit

    2006-05-01

    We report the development of a technique for adaptive selection of polarization ellipse tilt and ellipticity angles such that the target separation from clutter is maximized. From the radar scattering matrix [S] and its complex components, in phase and quadrature phase, the elements of the Mueller matrix are obtained. Then, by means of polarization synthesis, the radar cross section of the radar scatters are obtained at different transmitting and receiving polarization states. By designing a maximum average correlation height filter, we derive a target versus clutter distance measure as a function of four transmit and receive polarization state angles. The results of applying this method on real synthetic aperture radar imagery indicate a set of four transmit and receive angles that lead to maximum target versus clutter discrimination. These optimum angles are different for different targets. Hence, by adaptive control of the state of polarization of polarimetric radar, one can noticeably improve the discrimination of targets from clutter.

  6. Synthetic aperture radar image processing techniques for damage detection of FRP-concrete systems

    Science.gov (United States)

    Yu, Tzuyang

    2017-04-01

    Electromagnetic imaging enables researchers and engineers to assess the surface and subsurface condition of concrete structures using radar and microwave sensors. Among existing radar imaging methods, synthetic aperture radar (SAR) imaging offers flexible resolution for various purposes in condition assessment. In this paper, two novel SAR image processing techniques are reported for the subsurface condition assessment of FRP(fiber reinforced polymer)-strengthened concrete systems; mathematical morphology (MM) and the K-R-I transform. Glass FRP (GFRP) and carbon CFRP (CFRP) strengthened concrete cylinders are used as examples. From our experimental results, it is found that both techniques are capable of quantifying SAR images for condition assessment. It is also found that Euler's number and the coefficient of correlation of K-R-I curves of SAR images can be used for monitoring subsurface changes in FRP-concrete systems.

  7. 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.

  8. Digital Beamforming Synthetic Aperture Radar Developments at NASA Goddard Space Flight Center

    Science.gov (United States)

    Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung Kuk; Du Toit, Cornelis F.; Perrine, Martin; Ranson, K. Jon; Sun, Guoqing; Deshpande, Manohar; Beck, Jaclyn; hide

    2016-01-01

    Advanced Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) technology is an area of research and development pursued at the NASA Goddard Space Flight Center (GSFC). Advanced SAR architectures enhances radar performance and opens a new set of capabilities in radar remote sensing. DBSAR-2 and EcoSAR are two state-of-the-art radar systems recently developed and tested. These new instruments employ multiple input-multiple output (MIMO) architectures characterized by multi-mode operation, software defined waveform generation, digital beamforming, and configurable radar parameters. The instruments have been developed to support several disciplines in Earth and Planetary sciences. This paper describes the radars advanced features and report on the latest SAR processing and calibration efforts.

  9. Efficient Terahertz Wide-Angle NUFFT-Based Inverse Synthetic Aperture Imaging Considering Spherical Wavefront

    Directory of Open Access Journals (Sweden)

    Jingkun Gao

    2016-12-01

    Full Text Available An efficient wide-angle inverse synthetic aperture imaging method considering the spherical wavefront effects and suitable for the terahertz band is presented. Firstly, the echo signal model under spherical wave assumption is established, and the detailed wavefront curvature compensation method accelerated by 1D fast Fourier transform (FFT is discussed. Then, to speed up the reconstruction procedure, the fast Gaussian gridding (FGG-based nonuniform FFT (NUFFT is employed to focus the image. Finally, proof-of-principle experiments are carried out and the results are compared with the ones obtained by the convolution back-projection (CBP algorithm. The results demonstrate the effectiveness and the efficiency of the presented method. This imaging method can be directly used in the field of nondestructive detection and can also be used to provide a solution for the calculation of the far-field RCSs (Radar Cross Section of targets in the terahertz regime.

  10. The observation of ocean surface phenomena using imagery from the Seasat synthetic aperture radar - An assessment

    Science.gov (United States)

    Vesecky, J. F.; Stewart, R. H.

    1982-01-01

    The principles governing synthetic aperture radar (SAR) and its use on the Seasat spacecraft are reviewed. The way in which wind stress, surface currents, long gravity waves, and surface films modulate the scattering properties of resonant (approximately 30-cm-wavelength) waves is discussed, with particular emphasis placed on the mechanisms that could produce images of long gravity waves. Doppler effects by ocean motion are also described. Measurements of long (wavelength more than about 100 m) gravity waves made using Seasat SAR imagery are compared with surface measurements during several experiments. Combining these results, it is found that dominant wavelength and direction are measured by Seasat SAR within + or - 12% and + or - 15 deg, respectively. It is noted, however, that ocean waves are not always visible in SAR images, and detection criteria are discussed in terms of wave height, length, and direction.

  11. Three-Dimensional Synthetic Aperture Focusing Using a Rocking Convex Array Transducer

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Pedersen, Mads Møller

    2010-01-01

    Volumetric imaging can be performed using 1-D arrays in combination with mechanical motion. Outside the elevation focus of the array, the resolution and contrast quickly degrade compared with the lateral plane, because of the fixed transducer focus. This paper shows the feasibility of using...... and increase SNR at the elevation VS, a plane-wave VS approach has been implemented. Simulations and measurements using an experimental scanner with a convex rocking array show an average improvement in resolution of 26% and 33%, respectively. This improvement is also seen in in vivo measurements...... synthetic aperture focusing for enhancing the elevation focus for a convex rocking array. The method uses a virtual source (VS) for defocused multi-element transmit, and another VS in the elevation focus point. This allows a direct time-of-flight to be calculated for a given 3-D point. To avoid artifacts...

  12. 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...... covering agricultural fields near Foulum, Denmark, are used. Soon the Japanese ALOS, the German TerraSAR-X and the Canadian RADARSAT-2 will acquire space-borne, polarimetric data making analysis based on these methods important....... statistic for equality of two such matrices and an associated asymptotic probability for obtaining a smaller value of the test statistic are given and applied to change detection, edge detection and segmentation in polarimetric SAR data. In a case study EMISAR L-band data from 17 April 1998 and 20 May 1998...

  13. The laboratory demonstration and signal processing of the inverse synthetic aperture imaging ladar

    Science.gov (United States)

    Gao, Si; Zhang, ZengHui; Xu, XianWen; Yu, WenXian

    2017-10-01

    This paper presents a coherent inverse synthetic-aperture imaging ladar(ISAL)system to obtain high resolution images. A balanced coherent optics system in laboratory is built with binary phase coded modulation transmit waveform which is different from conventional chirp. A whole digital signal processing solution is proposed including both quality phase gradient autofocus(QPGA) algorithm and cubic phase function(CPF) algorithm. Some high-resolution well-focused ISAL images of retro-reflecting targets are shown to validate the concepts. It is shown that high resolution images can be achieved and the influences from vibrations of platform involving targets and radar can be automatically compensated by the distinctive laboratory system and digital signal process.

  14. Real-time Implementation of Synthetic Aperture Vector Flow Imaging on a Consumer-level Tablet

    DEFF Research Database (Denmark)

    di Ianni, Tommaso; Kjeldsen, Thomas Kim; Villagómez Hoyos, Carlos Armando

    2017-01-01

    In this work, a 2-D vector flow imaging (VFI) method based on synthetic aperture sequential beamforming (SASB) and directional transverse oscillation is implemented on a commercially available tablet. The SASB technique divides the beamforming process in two parts, whereby the required data rate...... and processed by a first-stage beamformer in a fixed focus. The data were subsequently transferred to an HTC Nexus 9 tablet through an ASUS RT-AC68U Wi-Fi router to simulate a wireless probe. The second-stage beamforming of the B-mode and flow data and the velocity estimation were implemented on the tablet......’s built-in GPU (Nvidia Tegra K1) through the OpenGL ES 3.1 API. Real-time performance was achieved with rates up to 26 VFI frames per second (38 ms/frame) for concurrent processing and Wi-Fi transmission....

  15. Synthetic Aperture Sequential Beamforming and other Beamforming Techniques in Ultrasound Imaging

    DEFF Research Database (Denmark)

    Kortbek, Jacob

    a moderate expansion. This is not sufficient to reduce the extent of the wide point spread function of a single emission. The advantage of SAF is the increase in SNR. For the setup with focal depth at 20 mm the SAF SNR gain is 11 dB. The other synthetic aperture focusing technique is similar but has been...... beamformer. There is an substantial improvement in lateral resolution using SASB compared to dynamic receive focusing (DRF). The improvement in FWHM is at least a factor of 2 and the improvement at -40 dB is at least a factor of 3. At depths until 20 mm the FWHM is superior with DRF.With SASB the resolution...... it is obvious that the lateral resolution is laterally dependent....

  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. Synthetic Aperture Focusing Technique for the Ultrasonic Evaluation of Friction Stir Welds

    Science.gov (United States)

    Lévesque, D.; Dubourg, L.; Mandache, C.; Kruger, S. E.; Lord, M.; Merati, A.; Jahazi, M.; Monchalin, J.-P.

    2008-02-01

    An ultrasonic technique using numerical focusing and processing is presented in this paper for the detection of different types of flaws in friction stir welds (FSW). The data is acquired using immersion ultrasonic technique or laser ultrasonics, while the Synthetic Aperture Focusing Technique (SAFT) is used for numerical focusing. Measurements on the top and far sides of the weld for both lap and butt joints of thin aluminum sheets are investigated. Discontinuities such as wormholes, hooking, lack of penetration and voids are found to be easily detected. The limit of detectability and a comparison with mechanical properties are discussed. Also, the detection of joint line remnants or kissing bonds due to entrapped oxide layers seems possible in lap joint structures using high frequency laser-ultrasonics.

  18. 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.

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

    Science.gov (United States)

    Ramsey, Elijah W.; 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.

  20. Fourier RGB synthetic aperture color holographic capture for wide angle holographic display

    Science.gov (United States)

    Gołoś, Anna; Zaperty, Weronika; Finke, Grzegorz; Makowski, Piotr; Kozacki, Tomasz

    2016-09-01

    In this work we present a high pixel count color holographic registration system that is designed to provide 3D holographic content of real-world large objects. Captured data is dedicated for holographic displays with a wide-viewing angle. The registration in color is realized by means of sequential recording with the use of three RGB laser light sources. The applied Fourier configuration of capture system gives large viewing angle and an optimal coverage of the detector resolution. Moreover, it enables to filter out zero order and twin image. In this work the captured Fourier holograms are transformed to general Fresnel type that is more suitable for 3D holographic displays. High resolution and large pixel count of holographic data and its spatial continuity is achieved through synthetic aperture concept with camera scanning and subpixel correlation based stitching. This grants an access to many tools of numerical hologram processing e.g. continuous viewing angle adjustment, and control of 3D image position and size. In this paper the properties of 1D synthetic aperture (60000 x 2500 pixels) are investigated. Each of the RGB 1D SA holograms is composed of 71 frames, which after stitching result in approx. 150 Megapixel hologram pixel count and 12° angular field of view. In experimental part high quality numerical reconstructions for each type of the hologram are shown. Moreover, the captured holograms are used for generation of hybrid hologram that is assembled from a set of RGB holograms of different color statues of height below 20 cm. In the final experiment this hybrid hologram as well as RGB hologram of a single object are reconstructed in the color holographic display.

  1. Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S. T. [Univ. of Wisconsin, Madison, WI (United States); Akerley, J. [Ormat Technologies Inc., Reno, NV (United States); Baluyut, E. C. [Univ. of Wisconsin, Madison, WI (United States); Cardiff, M. [Univ. of Wisconsin, Madison, WI (United States); Davatzes, N. C. [Temple Univ., Philadelphia, PA (United States). Dept. of Earth and Environmental Science; Feigl, K. L. [Univ. of Wisconsin, Madison, WI (United States); Foxall, W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fratta, D. [Univ. of Wisconsin, Madison, WI (United States); Mellors, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Spielman, P. [Ormat Technologies Inc., Reno, NV (United States); Wang, H. F. [Univ. of Wisconsin, Madison, WI (United States); Zemach, E. [Ormat Technologies Inc., Reno, NV (United States)

    2016-05-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area 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, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit 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 also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.

  2. Investigating ground deformation and subsidence in northern Metro Manila, Philippines using Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR)

    Science.gov (United States)

    Eco, R. C.; Lagmay, A. A.; Bato, M. P.

    2011-12-01

    The extent of ground deformation and subsidence in northern Metro Manila was examined using Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique. Using the Stanford Method for Persistent Scatterers/Multi-Temporal InSAR (StaMPS/MTI) software, we processed 21 descending ENVISAT radar imageries taken from 2003 to 2006. The processed interferograms show high coherence due to the high density of PS points in the region of interest. The PSInSAR processing reveals several areas in northern Metro Manila, specifically in Caloocan, Malabon, Navotas and Valenzuela-collectively known as CAMANAVA-that exhibit deformation characteristics similar to that of ground subsidence. Results show that the areas manifesting apparent subsidence are moving with a maximum rate of 4.38 cm/year relative to the satellite. This is consistent with the geodetic surveying results from 1979 to 2009 showing subsidence of approximately 1 meter or 3.33 cm/year per year. Government data also identify these areas as among those with the highest rates of groundwater extraction in Metro Manila, suggesting the possibility of anthropogenic activities as the major cause of subsidence. With this study, we hope to get a better understanding of the nature of subsidence affecting parts of northern Metro Manila. Doing so would help mitigate the effects of potential flood disasters.

  3. Characterization and classification of freshwater marshy wetland using synthetic aperture radar polarimetry: a case study from Loktak wetland, Northeast India

    Science.gov (United States)

    Padalia, Hitendra; Musthafa, Mohamed

    2017-01-01

    Loktak is the largest natural wetland of Northeast India, the last home of endangered brow-antlered deer, and a site of global significance recognized under Ramsar convention. Ecological and human-meditated spatial patterns of Loktak wetland were characterized and classified using a Radarsat-2 C band synthetic aperture radar (SAR) satellite data. Radarsat-2 quad-pol scene of dry season was preprocessed and classified using PolSARpro software. Eigen vector-eigen value decomposition of coherency matrix (T3) was performed to characterize the scattering properties of wetland targets based on entropy (H)/anisotropy (A)/alpha angle (α) segmentation. Results illustrate that RGB color display of H/A/α images is a useful indicator of wetland structure and composition, and provide clear visual discrimination of open water, floating phumdi, permanent phumdi cover, and associated man-made features. Six classes, namely, floating phumdi, permanent phumdi, scrub/shrub, fallow land, built-up, and open water were mapped using Wishart classification of H/A/α images. Scattering mechanisms of natural and man-made targets synthesized from PolSAR data, and their classification using Wishart algorithm have been validated through a visually classified map and field reference points. The land cover generated would be useful for conservation and management of Loktak wetland and brow-antlered deer population.

  4. 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.

  5. Forest type classification with combination of advanced polarimetric decompositions and textures of L-band synthetic aperture radar data

    Science.gov (United States)

    Middinti, Suresh; Jha, Chandra Shekhar; Reddy, Thatiparthi Byragi

    2017-01-01

    Information on distribution of forest types and land cover classes is essential for decision making and significant in climate regulation, biodiversity conservation, and societal issues. An approach for the combination of advanced polarimetric decompositions and textures of Advanced Land Observing Satellite Phased Array L-band Synthetic Aperture Radar full polarimetric data for the purpose of forest type classification is proposed. Using a support vector machine (SVM) classifier, we classified forest types over a selected Indian region. Further, we tested the classification performance of the Wishart method for the same forest types. The classified results were assessed with confusion matrix-based statistics. The results suggest that incorporation of various polarimetric decompositions features into gray-level co-occurrence matrix textures refines the SVM classification overall accuracy (OA) from 73.82% (k=0.69) to 76.34% (k=0.72). The Wishart supervised classification algorithm has the OA of 73.38% (kappa=0.68). We observed that integration of polarimetric information with textures can give complimentary information in forest type discrimination and produce high accuracy maps. Further, this approach overcomes the limitations of optical remote sensing data in continuous cloud coverage areas.

  6. Automatic Synthetic Aperture Radar based oil spill detection and performance estimation via a semi-automatic operational service benchmark.

    Science.gov (United States)

    Singha, Suman; Vespe, Michele; Trieschmann, Olaf

    2013-08-15

    Today the health of ocean is in danger as it was never before mainly due to man-made pollutions. Operational activities show regular occurrence of accidental and deliberate oil spill in European waters. Since the areas covered by oil spills are usually large, satellite remote sensing particularly Synthetic Aperture Radar represents an effective option for operational oil spill detection. This paper describes the development of a fully automated approach for oil spill detection from SAR. Total of 41 feature parameters extracted from each segmented dark spot for oil spill and 'look-alike' classification and ranked according to their importance. The classification algorithm is based on a two-stage processing that combines classification tree analysis and fuzzy logic. An initial evaluation of this methodology on a large dataset has been carried out and degree of agreement between results from proposed algorithm and human analyst was estimated between 85% and 93% respectively for ENVISAT and RADARSAT. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. 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.

    1994-11-01

    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 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.

  8. 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.

  9. Passive synthetic aperture sonar techniques in combination with tow ship noise canceling: application to a triplet towed array

    NARCIS (Netherlands)

    Colin, M.E.G.D.; Groen, J.

    2002-01-01

    An important issue in research on passive ASW operations is improvement in signal-to-noise ratio (SNR) and bearing resolution for targets emitting low frequency signals. One of the techniques believed to improve these characteristics is Synthetic Aperture Sonar (SAS). The method is based on the

  10. Directional velocity estimation using a spatio-temporal encoding technique based on frequency division for synthetic transmit aperture ultrasound

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2006-01-01

    This paper investigates the possibility of flow estimation using spatio-temporal encoding of the transmissions in synthetic transmit aperture imaging (STA). The spatial encoding is based on a frequency division approach. In STA, a major disadvantage is that only a single transmitter (denoting sin...

  11. Space-borne synthetic aperture radar of intertidal flat surfaces as a basis for predicting benthic macrofauna distribution

    NARCIS (Netherlands)

    Van der Wal, D.; Herman, P.M.J.; Ysebaert, T.

    2004-01-01

    High resolution, synoptic information on sediment characteristics of tidal flats is required for habitat mapping, and for assessing the distribution of benthic macrofauna. This study aims to derive information on surface characteristics of tidal flats from space-borne Synthetic Aperture Radar (SAR).

  12. Synthetic aperture acoustic imaging of canonical targets with a 2-15 kHz linear FM chirp

    Science.gov (United States)

    Vignola, Joseph F.; Judge, John A.; Good, Chelsea E.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

    2011-06-01

    Synthetic aperture image reconstruction applied to outdoor acoustic recordings is presented. Acoustic imaging is an alternate method having several military relevant advantages such as being immune to RF jamming, superior spatial resolution, capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to 0.5 - 3 GHz ground penetrating radar technologies. Synthetic aperture acoustic imaging is similar to synthetic aperture radar, but more akin to synthetic aperture sonar technologies owing to the nature of longitudinal or compressive wave propagation in the surrounding acoustic medium. The system's transceiver is a quasi mono-static microphone and audio speaker pair mounted on a rail 5meters in length. Received data sampling rate is 80 kHz with a 2- 15 kHz Linear Frequency Modulated (LFM) chirp, with a pulse repetition frequency (PRF) of 10 Hz and an inter-pulse period (IPP) of 50 milliseconds. Targets are positioned within the acoustic scene at slant range of two to ten meters on grass, dirt or gravel surfaces, and with and without intervening metallic chain link fencing. Acoustic image reconstruction results in means for literal interpretation and quantifiable analyses. A rudimentary technique characterizes acoustic scatter at the ground surfaces. Targets within the acoustic scene are first digitally spotlighted and further processed, providing frequency and aspect angle dependent signature information.

  13. 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.

  14. satellite synthetic observations heterogenety variability as studied from virtual catchment

    Science.gov (United States)

    Saavedra, Pablo; Simmer, Clemens

    2017-04-01

    The FOR2131 research unit is currently developing and improving data assimilation schemes for coupled subsurface-land surface-atmosphere models, namely the TerrSysMP comprised by ParFlow-CLM-COSMO models. That framework is used to test how different kinds of observations and networks of observations can improve system state estimation with a focus on in and inter-compartment fluxes of matter and heat energy. The focus of the present contribution is to analyze satellite observations (focus on SMOS and SMAP missions) which provide information on spatial and temporal scales that are hardly supported by in-situ observation networks. In that context, a satellite virtual observation operator has been developed in order to provide synthetic observation for the high spatial-resolution TerrSysMP model applied to the Neckar catchment in the south-west of Germany. Therefore, SMOS real and synthetic observations are used in order to understand the the effects on the microwave signature from the inclusion of sub-pixel land-surface heterogeneity which incorporates comparatively large-scale satellite observations in the data assimilation framework developed by the FOR2131 research unit. Preliminary results performed in a multi incident angle approach it is shown that SMOS real observations shows larger dynamic range as compared to the synthetic observations, while the temporal variability (daily bases) is good represented after a estimation of proper MW radiative transfer parameter specifically adjusted for the TerrSysMP Neckar catchment. This results focused on satellite observations, among other data sources, are mean to support and to confine the system states needed for the development of data assimilation framework by FOR2131.

  15. 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

  16. 3D synthetic aperture PIV measurements from artificial vibrating vocal folds

    CERN Document Server

    Daily, Jesse; Belden, Jesse; Thomson, Scott; Truscott, Tadd

    2011-01-01

    During speech, air from the lungs is forced past the vocal folds which vibrate, producing sound. A pulsatile jet of air is formed downstream of the vibrating folds which interacts with the various structures in the airway. Currently, it is postulated that the way this jet interacts with the downstream structures in the airway directly affects the quality of human speech. In order to better understand this jet, it is desirable to visualize the jet in three dimensions. We present the results of a method that reconstructs the three dimensional velocity field using Synthetic aperture PIV (SAPIV) \\cite{Belden:2010}. SAPIV uses an array of high-speed cameras to artificially create a single camera with a variable focal length. This is accomplished by overlapping the images from the array to create a "focal stack". As the images are increasingly overlapped, more distant image planes come into focus. 3D PIV is then performed on the "refocused" focal stack to reconstruct the flow field in three dimensions. SAPIV has th...

  17. Binaural Range Finding from Synthetic Aperture Computation as the Head is Turned

    Directory of Open Access Journals (Sweden)

    Duncan Tamsett

    2017-04-01

    Full Text Available A solution to binaural direction finding described in Tamsett (Robotics 2017, 6(1, 3 is a synthetic aperture computation (SAC performed as the head is turned while listening to a sound. A far-range approximation in that paper is relaxed in this one and the method extended for SAC as a function of range for estimating range to an acoustic source. An instantaneous angle λ (lambda between the auditory axis and direction to an acoustic source locates the source on a small circle of colatitude (lambda circle of a sphere symmetric about the auditory axis. As the head is turned, data over successive instantaneous lambda circles are integrated in a virtual field of audition from which the direction to an acoustic source can be inferred. Multiple sets of lambda circles generated as a function of range yield an optimal range at which the circles intersect to best focus at a point in a virtual three-dimensional field of audition, providing an estimate of range. A proof of concept is demonstrated using simulated experimental data. The method enables a binaural robot to estimate not only direction but also range to an acoustic source from sufficiently accurate measurements of arrival time/level differences at the antennae.

  18. Synthetic Aperture Computation as the Head is Turned in Binaural Direction Finding

    Directory of Open Access Journals (Sweden)

    Duncan Tamsett

    2017-03-01

    Full Text Available Binaural systems measure instantaneous time/level differences between acoustic signals received at the ears to determine angles λ between the auditory axis and directions to acoustic sources. An angle λ locates a source on a small circle of colatitude (a lamda circle on a sphere symmetric about the auditory axis. As the head is turned while listening to a sound, acoustic energy over successive instantaneous lamda circles is integrated in a virtual/subconscious field of audition. The directions in azimuth and elevation to maxima in integrated acoustic energy, or to points of intersection of lamda circles, are the directions to acoustic sources. This process in a robotic system, or in nature in a neural implementation equivalent to it, delivers its solutions to the aurally informed worldview. The process is analogous to migration applied to seismic profiler data, and to that in synthetic aperture radar/sonar systems. A slanting auditory axis, e.g., possessed by species of owl, leads to the auditory axis sweeping the surface of a cone as the head is turned about a single axis. Thus, the plane in which the auditory axis turns continuously changes, enabling robustly unambiguous directions to acoustic sources to be determined.

  19. DETECTION OF BUILT-UP AREAS USING POLARIMETRIC SYNTHETIC APERTURE RADAR DATA AND HYPERSPECTRAL IMAGE

    Directory of Open Access Journals (Sweden)

    R. Bordbari

    2015-12-01

    Full Text Available 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.

  20. Digital processing considerations for extraction of ocean wave image spectra from raw synthetic aperture radar data

    Science.gov (United States)

    Lahaie, I. J.; Dias, A. R.; Darling, G. D.

    1984-01-01

    The digital processing requirements of several algorithms for extracting the spectrum of a detected synthetic aperture radar (SAR) image from the raw SAR data are described and compared. The most efficient algorithms for image spectrum extraction from raw SAR data appear to be those containing an intermediate image formation step. It is shown that a recently developed compact formulation of the image spectrum in terms of the raw data is computationally inefficient when evaluated directly, in comparison with the classical method where matched-filter image formation is an intermediate result. It is also shown that a proposed indirect procedure for digitally implementing the same compact formulation is somewhat more efficient than the classical matched-filtering approach. However, this indirect procedure includes the image formation process as part of the total algorithm. Indeed, the computational savings afforded by the indirect implementation are identical to those obtained in SAR image formation processing when the matched-filtering algorithm is replaced by the well-known 'dechirp-Fourier transform' technique. Furthermore, corrections to account for slant-to-ground range conversion, spherical earth, etc., are often best implemented in the image domain, making intermediate image formation a valuable processing feature.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    Hongbo Mo

    2016-01-01

    Full Text Available 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 advantage of real time digital beamforming (DBF with null steering in elevation and azimuth multichannel raw data reconstruction. Echoes corresponding to different subpulses in the same subswath are separated by DBF with null steering onboard, while echoes received and stored by different azimuth channels are reconstructed by multiple Doppler reconstruction filters on the ground. Afterwards, the resulting MIMO-SAR raw data could be equivalent to the raw data of the single-channel burst mode, and classical burst mode imaging algorithms could be adopted to obtain final focused SAR images. Simulation results validate the proposed imaging approach.

  3. Synthetic aperture radar (SAR-based mapping of volcanic flows: Manam Island, Papua New Guinea

    Directory of Open Access Journals (Sweden)

    J. K. Weissel

    2004-01-01

    Full Text Available We present new radar-based techniques for efficient identification of surface changes generated by lava and pyroclastic flows, and apply these to the 1996 eruption of Manam Volcano, Papua New Guinea. Polarimetric L- and P-band airborne synthetic aperture radar (SAR data, along with a C-band DEM, were acquired over the volcano on 17 November 1996 during a major eruption sequence. The L-band data are analyzed for dominant scattering mechanisms on a per pixel basis using radar target decomposition techniques. A classification method is presented, and when applied to the L-band polarimetry, it readily distinguishes bare surfaces from forest cover over Manam volcano. In particular, the classification scheme identifies a post-1992 lava flow in NE Valley of Manam Island as a mainly bare surface and the underlying 1992 flow units as mainly vegetated surfaces. The Smithsonian's Global Volcanism Network reports allow us to speculate whether the bare surface is a flow dating from October or November in the early part of the late-1996 eruption sequence. This work shows that fully polarimetric SAR is sensitive to scattering mechanism changes caused by volcanic resurfacing processes such as lava and pyroclastic flows. By extension, this technique should also prove useful in mapping debris flows, ash deposits and volcanic landslides associated with major eruptions.

  4. GPU-accelerated two dimensional synthetic aperture focusing for photoacoustic microscopy

    Science.gov (United States)

    Liu, Siyu; Feng, Xiaohua; Gao, Fei; Jin, Haoran; Zhang, Ruochong; Luo, Yunqi; Zheng, Yuanjin

    2018-02-01

    Acoustic resolution photoacoustic microscopy (AR-PAM) generally suffers from limited depth of focus, which had been extended by synthetic aperture focusing techniques (SAFTs). However, for three dimensional AR-PAM, current one dimensional (1D) SAFT and its improved version like cross-shaped SAFT do not provide isotropic resolution in the lateral direction. The full potential of the SAFT remains to be tapped. To this end, two dimensional (2D) SAFT with fast computing architecture is proposed in this work. Explained by geometric modeling and Fourier acoustics theories, 2D-SAFT provide the narrowest post-focusing capability, thus to achieve best lateral resolution. Compared with previous 1D-SAFT techniques, the proposed 2D-SAFT improved the lateral resolution by at least 1.7 times and the signal-to-noise ratio (SNR) by about 10 dB in both simulation and experiments. Moreover, the improved 2D-SAFT algorithm is accelerated by a graphical processing unit that reduces the long period of reconstruction to only a few seconds. The proposed 2D-SAFT is demonstrated to outperform previous reported 1D SAFT in the aspects of improving the depth of focus, imaging resolution, and SNR with fast computational efficiency. This work facilitates future studies on in vivo deeper and high-resolution photoacoustic microscopy beyond several centimeters.

  5. Validating high-resolution California coastal flood modeling with Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR)

    Science.gov (United States)

    O'Neill, A.

    2015-12-01

    The Coastal Storm Modeling System (CoSMoS) is a numerical modeling scheme used to predict coastal flooding due to sea level rise and storms influenced by climate change, currently in use in central California and in development for Southern California (Pt. Conception to the Mexican border). Using a framework of circulation, wave, analytical, and Bayesian models at different geographic scales, high-resolution results are translated as relevant hazards projections at the local scale that include flooding, wave heights, coastal erosion, shoreline change, and cliff failures. Ready access to accurate, high-resolution coastal flooding data is critical for further validation and refinement of CoSMoS and improved coastal hazard projections. High-resolution Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) provides an exceptional data source as appropriately-timed flights during extreme tides or storms provide a geographically-extensive method for determining areas of inundation and flooding extent along expanses of complex and varying coastline. Landward flood extents are numerically identified via edge-detection in imagery from single flights, and can also be ascertained via change detection using additional flights and imagery collected during average wave/tide conditions. The extracted flooding positions are compared against CoSMoS results for similar tide, water level, and storm-intensity conditions, allowing for robust testing and validation of CoSMoS and providing essential feedback for supporting regional and local model improvement.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-05-27

    (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 stripmap mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers.

  7. Synthetic Aperture Focusing Technique in Ultrasonic Inspection of Coarse Grained Materials

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Tadeusz (Uppsala Univ., Signals and Systems, Box 528, SE-751 20 Uppsala (Sweden))

    2007-12-15

    Experience from the ultrasonic inspection of nuclear power plants has shown that large focused transducers are relatively effective in suppressing grain (structure) noise. Operation of a large focused transducer can be thought of as an integration (coherent summation) of individual beams reflected from the target and received by individual points at the transducer surface. Synthetic aperture focusing technique (SAFT), in its simplest version mimics an acoustic lens used for focusing beams at a desired point in the region of interest. Thus, SAFT should be able to suppress the grain noise in the similar way as the focused transducer does. This report presents the results of investigation of SAFT algorithms applied for post-processing of ultrasonic data acquired in inspection of coarse grained metals. The performance of SAFT in terms of its spatial (cross-range) resolution and grain noise suppression is studied. The evaluation is made based on the experimental data obtained from the ultrasonic inspection of test specimens with artificial defects (side drilled holes). SAFT algorithms for both contact and immersion mode are introduced and experimentally verified

  8. Modified multiple measurement vectors model for squinted synthetic aperture radar imaging

    Science.gov (United States)

    Chen, Yichang; Zhang, Qun; Chen, Yong-An; Sun, Li

    2017-05-01

    Inspired by the theoretical advances of compressed sensing, lots of sparsity-aware methods have been proposed for squinted synthetic aperture radar (SAR) imaging based on the single-measurement vector (SMV) model. Compared with SMV, the multiple measurement vectors (MMV) model has been demonstrated to have better reconstruction performance. In fact, echo received by SAR at different azimuth positions can be viewed as MMVs. However, the MMV model cannot be directly used in squinted SAR imaging, because MMV requires multiple sparse vectors of the common sparse structures, while the high-resolution range profiles (HRRPs) obtained by squinted SAR at different azimuth positions have different sparse structures due to range migration effect. A squinted SAR imaging method is proposed based on MMV. First, a modified MMV model that considers range migration is built to realize sparse representation of echo. Additionally, an improved orthogonal matching pursuit algorithm is developed to reconstruct HRRPs. Finally, a high-resolution two-dimensional image result can be easily achieved via traditional azimuth match filtering. Experimental results based on both simulated and real data demonstrate that the proposed MMV-based method can provide better computational efficiency and antinoise ability compared to the SMV-based method.

  9. X-SAR: The X-band synthetic aperture radar on board the Space Shuttle

    Science.gov (United States)

    Werner, Marian U.

    1993-01-01

    The X-band synthetic aperture radar (X-SAR) is the German/Italian contribution to the NASA/JPL Shuttle Radar Lab missions as part of the preparation for the Earth Observation System (EOS) program. The Shuttle Radar Lab is a combination of several radars: an L-band (1.2 GHz) and a C-band (5.3 GHz) multipolarization SAR known as SIR-C (Shuttle Imaging Radar); and an X-band (9.6 GHz) vertically polarized SAR which will be operated synchronously over the same target areas to deliver calibrated multifrequency and multipolarization SAR data at multiple incidence angles from space. A joint German/Italian project office at DARA (German Space Agency) is responsible for the management of the X-SAR project. The space hardware has been developed and manufactured under industrial contract by Dornier and Alenia Spazio. Besides supporting all the technical and scientific tasks, DLR, in cooperation with ASI (Agencia Spaziale Italiano) is responsible for mission operation, calibration, and high precision SAR processing. In addition, DLR developed an airborne X-band SAR to support the experimenters with campaigns to prepare for the missions. The main advantage of adding a shorter wavelength (3 cm) radar to the SIR-C radars is the X-band radar's weaker penetration into vegetation and soil and its high sensitivity to surface roughness and associated phenomena. The performance of each of the three radars is comparable with respect to radiometric and geometric resolution.

  10. Mangrove vegetation structure in Southeast Brazil from phased array L-band synthetic aperture radar data

    Science.gov (United States)

    de Souza Pereira, Francisca Rocha; Kampel, Milton; Cunha-Lignon, Marilia

    2016-07-01

    The potential use of phased array type L-band synthetic aperture radar (PALSAR) data for discriminating distinct physiographic mangrove types with different forest structure developments in a subtropical mangrove forest located in Cananéia on the Southern coast of São Paulo, Brazil, is investigated. The basin and fringe physiographic types and the structural development of mangrove vegetation were identified with the application of the Kruskal-Wallis statistical test to the SAR backscatter values of 10 incoherent attributes. The best results to separate basin to fringe types were obtained using copolarized HH, cross-polarized HV, and the biomass index (BMI). Mangrove structural parameters were also estimated using multiple linear regressions. BMI and canopy structure index were used as explanatory variables for canopy height, mean height, and mean diameter at breast height regression models, with significant R2=0.69, 0.73, and 0.67, respectively. The current study indicates that SAR L-band images can be used as a tool to discriminate physiographic types and to characterize mangrove forests. The results are relevant considering the crescent availability of freely distributed SAR images that can be more utilized for analysis, monitoring, and conservation of the mangrove ecosystem.

  11. 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.

  12. A sigma-delta-based sparse synthetic aperture beamformer for real-time 3-D ultrasound.

    Science.gov (United States)

    Inerfield, M; Lockwood, G R; Garverick, S L

    2002-02-01

    Sigma-delta modulation allows delay resolution in ultrasound beamformers to be achieved by simple clock cycle delays applied to the undecimated bit-stream, greatly reducing the complexity of the signal processing and the number of bits in the datapath. The simplifications offered by this technique have the potential for low power and portable operation in advanced systems such as 3-D and color Doppler imagers. In this paper, an architecture for a portable, real-time, 3-D sparse synthetic aperture ultrasound beamformer based on sigma-delta modulation is presented, and its simulated performance is analyzed. Specifically, with a 65-element linear phased array and three transmit events, this architecture is shown to achieve a 1.1 degrees beamwidth, a -54-dB secondary lobe level, and a theoretical frame rate of 1700 frames/s at lambda/64 delay resolution using a second-order low pass sigma-delta modulator. Finally, a technique for modifying the proposed multi-beam architecture to allow improved analog-to-digital (A/D) resolution by premodulating the input signal for bandpass sigma-delta modulation is also presented.

  13. Detecting Emergence, Growth, and Senescence of Wetland Vegetation with Polarimetric Synthetic Aperture Radar (SAR Data

    Directory of Open Access Journals (Sweden)

    Alisa L. Gallant

    2014-03-01

    Full Text Available Wetlands provide ecosystem goods and services vitally important to humans. Land managers and policymakers working to conserve wetlands require regularly updated information on the statuses of wetlands across the landscape. However, wetlands are challenging to map remotely with high accuracy and consistency. We investigated the use of multitemporal polarimetric synthetic aperture radar (SAR data acquired with Canada’s Radarsat-2 system to track within-season changes in wetland vegetation and surface water. We speculated, a priori, how temporal and morphological traits of different types of wetland vegetation should respond over a growing season with respect to four energy-scattering mechanisms. We used ground-based monitoring data and other ancillary information to assess the limits and consistency of the SAR data for tracking seasonal changes in wetlands. We found the traits of different types of vertical emergent wetland vegetation were detected well with the SAR data and corresponded with our anticipated backscatter responses. We also found using data from Landsat’s optical/infrared sensors in conjunction with SAR data helped remove confusion of wetland features with upland grasslands. These results suggest SAR data can provide useful monitoring information on the statuses of wetlands over time.

  14. Early Warning Monitoring of Natural and Engineered Slopes with Ground-Based Synthetic-Aperture Radar

    Science.gov (United States)

    Atzeni, C.; Barla, M.; Pieraccini, M.; Antolini, F.

    2015-01-01

    The first application of ground-based interferometric synthetic-aperture radar (GBInSAR) for slope monitoring dates back 13 years. Today, GBInSAR is used internationally as a leading-edge tool for near-real-time monitoring of surface slope movements in landslides and open pit mines. The success of the technology relies mainly on its ability to measure slope movements rapidly with sub-millimetric accuracy over wide areas and in almost any weather conditions. In recent years, GBInSAR has experienced significant improvements, due to the development of more advanced radar techniques in terms of both data processing and sensor performance. These improvements have led to widespread diffusion of the technology for early warning monitoring of slopes in both civil and mining applications. The main technical features of modern SAR technology for slope monitoring are discussed in this paper. A comparative analysis with other monitoring technologies is also presented along with some recent examples of successful slope monitoring.

  15. 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.

  16. 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.

  17. Millimeter-wave Interferometric Synthetic Aperture Radar Data Imaging Based on Terrain Surface Projection

    Directory of Open Access Journals (Sweden)

    Wei Shun-jun

    2015-02-01

    Full Text Available Millimeter-wave Interferometric Synthetic Aperture Radar (InSAR has smaller size, lower weight, and higher resolution compared with other bands. Thus, it has become a hot research topic. However, owing to its shorter wavelength, millimeter-wave InSAR data processing requires high-precision measurements of platform motion. For nonideal trajectories, traditional methods face difficulties in echo imaging and interferogram extraction. In addition, existing methods mainly produce SAR images based on plane projection. When the terrain changes abruptly, these methods may cause strong interferometric phase unwrapping and geometric distortion in SAR images. To overcome the abovementioned disadvantages of conventional methods in millimeter-wave InSAR imaging, an approach based on terrain surface projection is proposed. The echoes of different antennas are projected on the same terrain surface space for data imaging and interferogram extraction. In addition, the relation between terrain elevation and interferometric phase is derived. Simulations and experimental results verify the effectiveness of the proposed method; furthermore, the proposed approach improves the precision of interferometric phase extraction in complex motion conditions, while minimizing geometric distortion and phase wrapping in rough terrain, which is more conducive to terrain description and elevation inversion.

  18. Investigation of ground target detection methods in fully polarimetric wide angle synthetic aperture radar images

    Science.gov (United States)

    Laggan, Wayne B.

    1995-03-01

    Target detection is a high priority of the Air Force for the purpose of reconnaissance and bombardment. This research investigates and develops methods to distinguish ground targets from clutter (i.e. foliage, landscape etc.) in Wide Angle Synthetic Aperture Radar (WASAR) images. WASAR uses multiple aspect angle SAR images of the same target scene. The WASAR data was generated from a pre-release software package (XPATCH-ES) provided by the sponsor (WL-AARA). A statistical analysis and feature extraction is performed on the XPATCH-ES data. Polarimetric and wide angle covariance matrices are estimated and analyzed. From an analysis of the wide angle covariance matrix it is shown that natural clutter has in general a uniform radar return for changing aspect angles, whereas the radar return for a target varies. Based on this analysis, two new wide angle algorithms, the WASAR Whitening Filter and the Adaptive WASAR Whitening Filter (AWWF) are developed. The target detection performance of polarimetric and multi aspect angle image combining algorithms are quantified using Receiver Operating Characteristic curves and target to clutter ratios. It is shown that wide angle processing provides superior target detection performance over polarimetric processing. Combinations of wide angle and polarimetric algorithms were used to achieve a 13.7 dB processing gain in target to clutter ratio when compared to unprocessed images of the target scene. This represents a significant improvement in target detection capabilities.

  19. Volumetric localization of epileptic activities in tuberous sclerosis using synthetic aperture magnetometry

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Zheng [Hospital for Sick Children, Research Institute, Toronto (Canada); Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Xiang, Jing [Hospital for Sick Children, Research Institute, Toronto (Canada); Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Holowka, Stephanie; Chuang, Sylvester [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Hunjan, Amrita; Sharma, Rohit; Otsubo, Hiroshi [Hospital for Sick Children, Division of Neurology, Toronto (Canada)

    2006-01-01

    Magnetoencephalography (MEG) is a novel noninvasive technique for localizing epileptic zones. Tuberous sclerosis complex (TSC) is often associated with medically refractory epilepsy with multiple epileptic zones. Surgical treatment of TSC requires accurate localization of epileptogenic tubers. The objective of this study was to introduce a new MEG technique, synthetic aperture magnetometry (SAM), to volumetrically localize irritable zones and clarify the correlations between SAM, dipole modeling and anatomical tubers. Eight pediatric patients with TSC confirmed by clinical and neuroimaging findings were retrospectively studied. MEG data were recorded using a whole-cortex CTF OMEGA system. Sleep deprivation was employed to provoke epileptiform activity. Irritable zones were localized using both dipole modeling and SAM. MRI detected 42 tubers in the eight patients. Dipole modeling localized 28 irritable zones, and 19 out of the 28 zones were near tubers (19/42, 45%). SAM found 51 irritable zones, and 31 out of the 51 zones were near tubers (31/42, 74%). Among the 51 irritable zones determined by SAM, thirty-five zones were in 1-35 Hz, nine zones were in 35-60 Hz, and seven zones were in 60-120 Hz. The new method, SAM, yielded very plausible equivalent sources for patients who showed anatomical tubers on MRI. Compared to conventional dipole modeling, SAM appeared to offer increased detection of irritable zones and beneficial volumetric and frequency descriptions. (orig.)

  20. Two-Stage Multi-Task Representation Learning for Synthetic Aperture Radar (SAR Target Images Classification

    Directory of Open Access Journals (Sweden)

    Xinzheng Zhang

    2017-11-01

    Full Text Available In this paper, we propose a two-stage multi-task learning representation method for the classification of synthetic aperture radar (SAR target images. The first stage of the proposed approach uses multi-features joint sparse representation learning, modeled as a ℓ 2 , 1 -norm regularized multi-task sparse learning problem, to find an effective subset of training samples. Then, a new dictionary is constructed based on the training subset. The second stage of the method is to perform target images classification based on the new dictionary, utilizing multi-task collaborative representation. The proposed algorithm not only exploits the discrimination ability of multiple features but also greatly reduces the interference of atoms that are irrelevant to the test sample, thus effectively improving classification performance. Conducted with the Moving and Stationary Target Acquisition and Recognition (MSTAR public SAR database, experimental results show that the proposed approach is effective and superior to many state-of-the-art methods.

  1. An approach for detecting changes related to natural disasters using Synthetic Aperture Radar data

    Science.gov (United States)

    Milisavljevic, N.; Closson, D.; Holecz, F.; Collivignarelli, F.; Pasquali, P.

    2015-04-01

    Land-cover changes occur naturally in a progressive and gradual way, but they may happen rapidly and abruptly sometimes. Very high resolution remote sensed data acquired at different time intervals can help in analyzing the rate of changes and the causal factors. In this paper, we present an approach for detecting changes related to disasters such as an earthquake and for mapping of the impact zones. The approach is based on the pieces of information coming from SAR (Synthetic Aperture Radar) and on their combination. The case study is the 22 February 2011 Christchurch earthquake. The identification of damaged or destroyed buildings using SAR data is a challenging task. The approach proposed here consists in finding amplitude changes as well as coherence changes before and after the earthquake and then combining these changes in order to obtain richer and more robust information on the origin of various types of changes possibly induced by an earthquake. This approach does not need any specific knowledge source about the terrain, but if such sources are present, they can be easily integrated in the method as more specific descriptions of the possible classes. A special task in our approach is to develop a scheme that translates the obtained combinations of changes into ground information. Several algorithms are developed and validated using optical remote sensing images of the city two days after the earthquake, as well as our own ground-truth data. The obtained validation results show that the proposed approach is promising.

  2. Bandwidth compression of synthetic aperture radar imagery by quantization of raw radar data

    Science.gov (United States)

    Lipes, R. G.; Butman, S. A.

    1977-01-01

    A study is made of the effects of quantization of the radar returns transmitted from aircraft or spacecraft employing a synthetic aperture radar system. The study is based on the output images obtained after one-bit, two-bit, and eight-bit quantizations and comparing the results to ground truth. In this way the degradation resulting from data or bandwidth reduction is determined. Quantization is evaluated in terms of crater scene, number of looks, and transmission error rate. It is found that two-bit quantization of raw radar data from homogeneous scenes processed to 32 looks yields nearly all the details of the original. One-bit quantization of raw radar data from homogeneous scenes processed to 32 looks yields a good visual representation of the scene but some fine detail is lost and the absolute reflectivity level is not reliable. Image quality is observed to improve with more looks and video and intermediate frequency quantization are not distinguishable even for one-bit quantizations. Image quality is not influenced by bit error rates less than about 2 to the -7th power.

  3. Realization of strong backscattering homogeneous regions with known backscattering coefficient in synthetic aperture radar images

    Science.gov (United States)

    Lin, Xin; Wang, Kaizhi; Wang, Junfeng; Liu, Xingzhao

    2017-01-01

    The strong backscattering homogeneous region, i.e., a uniform region with a high and constant backscattering coefficient, is important for synthetic aperture radar (SAR) image quality assessment and SAR radiometric calibration, which, however, is difficult to realize in practice with a known backscattering coefficient. We realize a strong backscattering homogeneous region with a known backscattering coefficient in SAR images by utilizing designed metal grids. First, we propose a manmade grid-structure target and realize it with aluminum in practice, which is named the metal grid. Then, the backscattering coefficient of the designed metal grid is simulated in the computer simulation technology (CST) microwave studio and measured by a radar cross-section (RCS) measurement instrument in a microwave anechoic chamber. Both CST simulation results and RCS measurement results confirm the strong backscattering property of the designed target. In addition, by utilizing the designed target, we realize a test field consisting of several strong backscattering homogeneous regions with different sizes at Shanghai Jiao Tong University, Shanghai, China. The spaceborne experiments have been carried out by the TerraSAR-X sensor over the test field in two flight campaigns in X-band with VV polarization. Experimental results demonstrate the strong backscattering property and homogeneity of the realized regions.

  4. A Fast Synthetic Aperture Radar Raw Data Simulation Using Cloud Computing

    Directory of Open Access Journals (Sweden)

    Zhixin Li

    2017-01-01

    Full Text Available Synthetic Aperture Radar (SAR raw data simulation is a fundamental problem in radar system design and imaging algorithm research. The growth of surveying swath and resolution results in a significant increase in data volume and simulation period, which can be considered to be a comprehensive data intensive and computing intensive issue. Although several high performance computing (HPC methods have demonstrated their potential for accelerating simulation, the input/output (I/O bottleneck of huge raw data has not been eased. In this paper, we propose a cloud computing based SAR raw data simulation algorithm, which employs the MapReduce model to accelerate the raw data computing and the Hadoop distributed file system (HDFS for fast I/O access. The MapReduce model is designed for the irregular parallel accumulation of raw data simulation, which greatly reduces the parallel efficiency of graphics processing unit (GPU based simulation methods. In addition, three kinds of optimization strategies are put forward from the aspects of programming model, HDFS configuration and scheduling. The experimental results show that the cloud computing based algorithm achieves 4_ speedup over the baseline serial approach in an 8-node cloud environment, and each optimization strategy can improve about 20%. This work proves that the proposed cloud algorithm is capable of solving the computing intensive and data intensive issues in SAR raw data simulation, and is easily extended to large scale computing to achieve higher acceleration.

  5. A Fast Synthetic Aperture Radar Raw Data Simulation Using Cloud Computing.

    Science.gov (United States)

    Li, Zhixin; Su, Dandan; Zhu, Haijiang; Li, Wei; Zhang, Fan; Li, Ruirui

    2017-01-08

    Synthetic Aperture Radar (SAR) raw data simulation is a fundamental problem in radar system design and imaging algorithm research. The growth of surveying swath and resolution results in a significant increase in data volume and simulation period, which can be considered to be a comprehensive data intensive and computing intensive issue. Although several high performance computing (HPC) methods have demonstrated their potential for accelerating simulation, the input/output (I/O) bottleneck of huge raw data has not been eased. In this paper, we propose a cloud computing based SAR raw data simulation algorithm, which employs the MapReduce model to accelerate the raw data computing and the Hadoop distributed file system (HDFS) for fast I/O access. The MapReduce model is designed for the irregular parallel accumulation of raw data simulation, which greatly reduces the parallel efficiency of graphics processing unit (GPU) based simulation methods. In addition, three kinds of optimization strategies are put forward from the aspects of programming model, HDFS configuration and scheduling. The experimental results show that the cloud computing based algorithm achieves 4_ speedup over the baseline serial approach in an 8-node cloud environment, and each optimization strategy can improve about 20%. This work proves that the proposed cloud algorithm is capable of solving the computing intensive and data intensive issues in SAR raw data simulation, and is easily extended to large scale computing to achieve higher acceleration.

  6. Detecting emergence, growth, and senescence of wetland vegetation with polarimetric synthetic aperture radar (SAR) data

    Science.gov (United States)

    Gallant, Alisa L.; Kaya, Shannon G.; White, Lori; Brisco, Brian; Roth, Mark F.; Sadinski, Walter J.; Rover, Jennifer

    2014-01-01

    Wetlands provide ecosystem goods and services vitally important to humans. Land managers and policymakers working to conserve wetlands require regularly updated information on the statuses of wetlands across the landscape. However, wetlands are challenging to map remotely with high accuracy and consistency. We investigated the use of multitemporal polarimetric synthetic aperture radar (SAR) data acquired with Canada’s Radarsat-2 system to track within-season changes in wetland vegetation and surface water. We speculated, a priori, how temporal and morphological traits of different types of wetland vegetation should respond over a growing season with respect to four energy-scattering mechanisms. We used ground-based monitoring data and other ancillary information to assess the limits and consistency of the SAR data for tracking seasonal changes in wetlands. We found the traits of different types of vertical emergent wetland vegetation were detected well with the SAR data and corresponded with our anticipated backscatter responses. We also found using data from Landsat’s optical/infrared sensors in conjunction with SAR data helped remove confusion of wetland features with upland grasslands. These results suggest SAR data can provide useful monitoring information on the statuses of wetlands over time.

  7. An Optimal DEM Reconstruction Method for Linear Array Synthetic Aperture Radar Based on Variational Model

    Directory of Open Access Journals (Sweden)

    Shi Jun

    2015-02-01

    Full Text Available Downward-looking Linear Array Synthetic Aperture Radar (LASAR has many potential applications in the topographic mapping, disaster monitoring and reconnaissance applications, especially in the mountainous area. However, limited by the sizes of platforms, its resolution in the linear array direction is always far lower than those in the range and azimuth directions. This disadvantage leads to the blurring of Three-Dimensional (3D images in the linear array direction, and restricts the application of LASAR. To date, the research on 3D SAR image enhancement has focused on the sparse recovery technique. In this case, the one-to-one mapping of Digital Elevation Model (DEM brakes down. To overcome this, an optimal DEM reconstruction method for LASAR based on the variational model is discussed in an effort to optimize the DEM and the associated scattering coefficient map, and to minimize the Mean Square Error (MSE. Using simulation experiments, it is found that the variational model is more suitable for DEM enhancement applications to all kinds of terrains compared with the Orthogonal Matching Pursuit (OMPand Least Absolute Shrinkage and Selection Operator (LASSO methods.

  8. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Bechsgaard, Thor

    2016-01-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view...... (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter...... vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow anglein the ROI was 86.22◦ ± 6.66◦ with a true flow angle of 90◦. A relative velocity bias of −39% with a standard deviation of 13% was found...

  9. Synthetic transmit aperture technique in medical ultrasound imaging implemented on a GPU

    Science.gov (United States)

    Li, Ying; Chen, Xiaodong; Zhang, Chuang; Wang, Yi; Jiao, Zhihai; Yu, Daoyin

    2014-11-01

    In the medical ultrasound imaging, the synthetic transmit aperture (STA) technique is very promising and has been a hot research topic. It is dynamically focused in both transmit and receive yielding an improvement in resolution. But this imaging technique sets high demands on processing capabilities and makes implementation of a full STA system very challenging and costly. Many attempts have been made to reduce the demands on the system making it a more realistic task to implement. In this paper we don't consider how to reduce the demands, but consider how to accelerate the processing speed of the system. The recent introduction of general-purpose graphic processing units (GPU) seems to be quite promising in this view, especially for the affordable programming complexity. In this paper we explain the main computational features of STA processing unit, trying to disclose the degree of parallelism in the operations. On the basis of the compute unified device architecture (CUDA) programming model and the extremely flexible structure of the Single Instruction Multiple Threads (SIMT) model, we show that the optimization of STA processing unit can be performed more efficiently. The input data is read from Matlab, the post-processing and display also use Matlab. Performance shows that, using a single NIVDIA GTX-650 GPU board, this amount to a speed up of more than a factor of 30 compared to a highly optimized beamformer running on our test workstation with a 3.20-GHz Intel Core-i5 processor.

  10. A Fast Level Set Method for Synthetic Aperture Radar Ocean Image Segmentation

    Science.gov (United States)

    Huang, Xiaoxia; Huang, Bo; Li, Hongga

    2009-01-01

    Segmentation of high noise imagery like Synthetic Aperture Radar (SAR) images is still one of the most challenging tasks in image processing. While level set, a novel approach based on the analysis of the motion of an interface, can be used to address this challenge, the cell-based iterations may make the process of image segmentation remarkably slow, especially for large-size images. For this reason fast level set algorithms such as narrow band and fast marching have been attempted. Built upon these, this paper presents an improved fast level set method for SAR ocean image segmentation. This competent method is dependent on both the intensity driven speed and curvature flow that result in a stable and smooth boundary. Notably, it is optimized to track moving interfaces for keeping up with the point-wise boundary propagation using a single list and a method of fast up-wind scheme iteration. The list facilitates efficient insertion and deletion of pixels on the propagation front. Meanwhile, the local up-wind scheme is used to update the motion of the curvature front instead of solving partial differential equations. Experiments have been carried out on extraction of surface slick features from ERS-2 SAR images to substantiate the efficacy of the proposed fast level set method. PMID:22399940

  11. Synthetic aperture imaging for multilayer cylindrical object using an exterior rotating transducer

    Science.gov (United States)

    Wu, Shiwei; Skjelvareid, Martin H.; Yang, Keji; Chen, Jian

    2015-08-01

    The synthetic aperture focusing technique (SAFT) with significant improvements in lateral resolution has been adapted for ultrasound imaging of multilayer objects. To apply SAFT to imaging of cylindrical objects such as solid axles or pipes with small diameter, exterior cylindrical scan is much preferred. In this paper, a frequency-domain algorithm is proposed for such cylindrical scan performed with an exterior rotating transducer. The algorithm is derived from Fourier-domain solutions to the waveequation in cylindrical coordinates, and then extended to the multilayer case. A simulation model for multilayer structure is established, and the algorithm is demonstrated for both simulated and experimental data. Compared with the raw images, the reconstructed images with proposed algorithm attain better lateral resolution for multilayer objects. It is shown that the attainable angular resolution for each layer is approximately consistent with that achieved in the single-layer case, as long as the transmission factors are approximately uniform within the divergence angle of the transducer. The performance of proposed algorithm is verified with experimental C-scan image and demonstrates that it is capable of improving the lateral resolution in both scanning directions.

  12. Frequency domain synthetic aperture focusing technique for variable-diameter cylindrical components.

    Science.gov (United States)

    Jin, Haoran; Wu, Eryong; Han, Ye; Yang, Keji; Chen, Jian

    2017-09-01

    Ultrasonic non-destructive testing (UNDT) plays an important role in ensuring the quality of cylindrical components of equipment such as pipes and axles. As the acoustic beam width widens along propagation depths, the diffraction of acoustic wave becomes serious and the images of defects will be interfered with. To precisely evaluate the dimensions of defects and flaws concealed in components, the synthetic aperture focusing technique (SAFT) is introduced to enhance the image resolutions. Conventional SAFTs have been successfully implemented for the ultrasonic imaging of normal cylinders, while solutions for complex ones, such as variable-diameter cylinders, are still lacking. To overcome this problem, a frequency-domain SAFT for variable-diameter cylindrical components is proposed. This algorithm is mainly based on acoustic field extrapolation, which is modified from cylindrical phase shift migration with the aid of split-step Fourier. After a series of extrapolations, a high-resolution ultrasound image can be reconstructed using a particular imaging condition. According to the experimental results, the proposed method yields low side lobes and high resolutions for flat transducers. Its attainable angular resolution relies on the transducer diameter D and scanning radius R and approximates D/(2R).

  13. Improving synthetic aperture focusing technique for thick concrete specimens via frequency banding

    Science.gov (United States)

    Clayton, Dwight A.

    2016-04-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. While standard Synthetic Aperture Focusing Technique (SAFT) is adequate for many defects with shallow concrete cover, some defects located under deep concrete cover are not easily identified using the standard SAFT. For many defects, particularly defects under deep cover, the use of frequency banded SAFT improves the detectability over standard SAFT. In addition to the improved detectability, the frequency banded SAFT also provides improved scan depth resolution that can be important in determining the suitability of a particular structure to perform its designed safety function. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To validate the advantages of frequency banded SAFT on thick concrete, a 2.134 m x 2.134 m x 1.016 m concrete test specimen with twenty deliberately embedded defects was fabricated.

  14. Generalized frequency-domain synthetic aperture focusing technique for ultrasonic imaging of irregularly layered objects.

    Science.gov (United States)

    Qin, Kaihuai; Yang, Chun; Sun, Feng

    2014-01-01

    In ultrasonic nondestructive testing (NDT), the phase shift migration (PSM) technique, as a frequency-domain implementation of the synthetic aperture focusing technique (SAFT), can be adopted for imaging of regularly layered objects that are inhomogeneous only in depth but isotropic and homogeneous in the lateral direction. To deal with irregularly layered objects that are anisotropic and inhomogeneous in both the depth and lateral directions, a generalized frequency- domain SAFT, called generalized phase shift migration (GPSM), is proposed in this paper. Compared with PSM, the most significant innovation of GPSM is that the phase shift factor is generalized to handle anisotropic media with lateral velocity variations. The generalization is accomplished by computer programming techniques without modifying the PSM model. In addition, SRFFT (split-radix fast Fourier transform) input/output pruning algorithms are developed and employed in the GPSM algorithm to speed up the image reconstructions. The experiments show that the proposed imaging techniques are capable of reconstructing accurate shapes and interfaces of irregularly layered objects. The computing time of the GPSM algorithm is much less than the time-domain SAFT combined with the ray-tracing technique, which is, at present, the common method used in ultrasonic NDT industry for imaging layered objects. Furthermore, imaging regularly layered objects can be regarded as a special case of the presented technique.

  15. Terrain classification of polarimetric synthetic aperture radar imagery based on polarimetric features and ensemble learning

    Science.gov (United States)

    Huang, Chuanbo

    2017-04-01

    An evolutionary classification system for terrain classification of polarimetric synthetic aperture radar (PolSAR) imagery based on ensemble learning with polarimetric and texture features is proposed. Polarimetric measurements cannot produce sufficient identification information for PolSAR terrain classification in some complex areas. To address this issue, texture features have been successfully used in image segmentation. The system classification feature has been adopted using a combination of Pauli features and the last principal component of Gabor texture-feature dimensionality reduction. The resulting feature combination assigned through experimental analysis is very suitable for describing structural and spatial information. To obtain a good integration effect, the basic classifier should be as precise as possible and the differences among the features should be as distinct as possible. We therefore examine and construct an ensemble-weighted voting classifier, including two support vector machine models that are constructed using kernel functions of the radial basis and sigmoid, extreme learning machine, k-nearest neighbor, and discriminant analysis classifier, which can avoid redundancy and bias because of different theoretical backgrounds. An experiment was performed to estimate the proposed algorithm's performance. The results verified that the algorithm can obtain better accuracy than the four classifiers mentioned in this paper.

  16. Multibaseline polarimetric synthetic aperture radar tomography of forested areas using wavelet-based distribution compressive sensing

    Science.gov (United States)

    Liang, Lei; Li, Xinwu; Gao, Xizhang; Guo, Huadong

    2015-01-01

    The three-dimensional (3-D) structure of forests, especially the vertical structure, is an important parameter of forest ecosystem modeling for monitoring ecological change. Synthetic aperture radar tomography (TomoSAR) provides scene reflectivity estimation of vegetation along elevation coordinates. Due to the advantages of super-resolution imaging and a small number of measurements, distribution compressive sensing (DCS) inversion techniques for polarimetric SAR tomography were successfully developed and applied. This paper addresses the 3-D imaging of forested areas based on the framework of DCS using fully polarimetric (FP) multibaseline SAR interferometric (MB-InSAR) tomography at the P-band. A new DCS-based FP TomoSAR method is proposed: a new wavelet-based distributed compressive sensing FP TomoSAR method (FP-WDCS TomoSAR method). The method takes advantage of the joint sparsity between polarimetric channel signals in the wavelet domain to jointly inverse the reflectivity profiles in each channel. The method not only allows high accuracy and super-resolution imaging with a low number of acquisitions, but can also obtain the polarization information of the vertical structure of forested areas. The effectiveness of the techniques for polarimetric SAR tomography is demonstrated using FP P-band airborne datasets acquired by the ONERA SETHI airborne system over a test site in Paracou, French Guiana.

  17. Application of Deep Networks to Oil Spill Detection Using Polarimetric Synthetic Aperture Radar Images

    Directory of Open Access Journals (Sweden)

    Guandong Chen

    2017-09-01

    Full Text Available Polarimetric synthetic aperture radar (SAR remote sensing provides an outstanding tool in oil spill detection and classification, for its advantages in distinguishing mineral oil and biogenic lookalikes. Various features can be extracted from polarimetric SAR data. The large number and correlated nature of polarimetric SAR features make the selection and optimization of these features impact on the performance of oil spill classification algorithms. In this paper, deep learning algorithms such as the stacked autoencoder (SAE and deep belief network (DBN are applied to optimize the polarimetric feature sets and reduce the feature dimension through layer-wise unsupervised pre-training. An experiment was conducted on RADARSAT-2 quad-polarimetric SAR image acquired during the Norwegian oil-on-water exercise of 2011, in which verified mineral, emulsions, and biogenic slicks were analyzed. The results show that oil spill classification achieved by deep networks outperformed both support vector machine (SVM and traditional artificial neural networks (ANN with similar parameter settings, especially when the number of training data samples is limited.

  18. A Geosynchronous Synthetic Aperture Provides for Disaster Management, Measurement of Soil Moisture, and Measurement of Earth-Surface Dynamics

    Science.gov (United States)

    Madsen, Soren; Komar, George (Technical Monitor)

    2001-01-01

    A GEO-based Synthetic Aperture Radar (SAR) could provide daily coverage of basically all of North and South America with very good temporal coverage within the mapped area. This affords a key capability to disaster management, tectonic mapping and modeling, and vegetation mapping. The fine temporal sampling makes this system particularly useful for disaster management of flooding, hurricanes, and earthquakes. By using a fairly long wavelength, changing water boundaries caused by storms or flooding could be monitored in near real-time. This coverage would also provide revolutionary capabilities in the field of radar interferometry, including the capability to study the interferometric signature immediately before and after an earthquake, thus allowing unprecedented studies of Earth-surface dynamics. Preeruptive volcano dynamics could be studied as well as pre-seismic deformation, one of the most controversial and elusive aspects of earthquakes. Interferometric correlation would similarly allow near real-time mapping of surface changes caused by volcanic eruptions, mud slides, or fires. Finally, a GEO SAR provides an optimum configuration for soil moisture measurement that requires a high temporal sampling rate (1-2 days) with a moderate spatial resolution (1 km or better). From a technological point of view, the largest challenges involved in developing a geosynchronous SAR capability relate to the very large slant range distance from the radar to the mapped area. This leads to requirements for large power or alternatively very large antenna, the ability to steer the mapping area to the left and right of the satellite, and control of the elevation and azimuth angles. The weight of this system is estimated to be 2750 kg and it would require 20 kW of DC-power. Such a system would provide up to a 600 km ground swath in a strip-mapping mode and 4000 km dual-sided mapping in a scan-SAR mode.

  19. Joint synthetic aperture radar plus ground moving target indicator from single-channel radar using compressive sensing

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Douglas; Hallquist, Aaron; Anderson, Hyrum

    2017-10-17

    The various embodiments presented herein relate to utilizing an operational single-channel radar to collect and process synthetic aperture radar (SAR) and ground moving target indicator (GMTI) imagery from a same set of radar returns. In an embodiment, data is collected by randomly staggering a slow-time pulse repetition interval (PRI) over a SAR aperture such that a number of transmitted pulses in the SAR aperture is preserved with respect to standard SAR, but many of the pulses are spaced very closely enabling movers (e.g., targets) to be resolved, wherein a relative velocity of the movers places them outside of the SAR ground patch. The various embodiments of image reconstruction can be based on compressed sensing inversion from undersampled data, which can be solved efficiently using such techniques as Bregman iteration. The various embodiments enable high-quality SAR reconstruction, and high-quality GMTI reconstruction from the same set of radar returns.

  20. Atmospheric corrections in interferometric synthetic aperture radar surface deformation – a case study of the city of Mendoza, Argentina

    OpenAIRE

    S. Balbarani; Euillades, P. A.; Euillades, L. D.; Casu, F.; Riveros, N. C.

    2013-01-01

    Differential interferometry is a remote sensing technique that allows studying crustal deformation produced by several phenomena like earthquakes, landslides, land subsidence and volcanic eruptions. Advanced techniques, like small baseline subsets (SBAS), exploit series of images acquired by synthetic aperture radar (SAR) sensors during a given time span. Phase propagation delay in the atmosphere is the main systematic error of interferometric SAR measurements. It affects differently images ...

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

    OpenAIRE

    Michelle Hofton; Naiara Pinto; Marco Lavalle; Ralph Dubayah; Scott Hensley; Marc Simard

    2012-01-01

    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 theore...

  2. Polarimetric Analysis of Backscatter From the Deepwater Horizon Oil Spill Using L-Band Synthetic Aperture Radar

    OpenAIRE

    Minchew, Brent; Jones, Cathleen E.; Holt, Benjamin

    2012-01-01

    We analyze the fully-polarimetric Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data acquired on June 23, 2010, from two adjacent, overlapping flight tracks that imaged the main oil slick near the Deepwater Horizon (DWH) rig site in the Gulf of Mexico. Our results show that radar backscatter from both clean water and oil in the slick is predominantly from a single surface scatterer, consistent with the tilted Bragg scattering mechanism, across the range of incidence angles from...

  3. Using Synthetic Aperture Radar to Study River Ice Breakup on the Kuparuk River, Northern Alaska

    Science.gov (United States)

    Floyd, A.; Prakash, A.; Meyer, F. J.; Gens, R.; Liljedahl, A. K.

    2012-12-01

    A combined use of remote sensing techniques and in-situ measurements is an effective approach to study Arctic hydrology, given the vastness, complexity, and logistical challenges posed by most Arctic watersheds. Remote sensing techniques can provide tools to assess the geospatial variations that form the integrated response of a river system and, therefore, provide important details to study one of the effects of climate change on the remote Arctic environment. This study investigates the breakup response of the Kuparuk River on the North Slope of Alaska using synthetic aperture radar (SAR). Imagery and runoff data collected during the spring and summer months between 2001 and 2010 from the Lower Kuparuk River are included in the analysis, which totals 65 SAR images. Image processing results have been calibrated with in-situ stream gauge data provided by USGS gauging station 15896000, on the Lower Kuparuk River, near the town of Deadhorse, Alaska. A time series was assembled to examine the breakup initiation in the subsets through statistical analysis. Images were stacked, geocoded using a Fast Fourier Transform, subset, masked, and divided into subsections. The statistics of each subsection were then compiled and analyzed. Arctic river breakup is a dynamic process. Therefore, we expected drastic change in river surface conditions to correspond to a large variance in backscatter between river subsections. However, before and after breakup we expected image subsections to have largely homogenous statistics. This was verified in nearly all of the image sets, although some variance still existed before and after the breakup event as a result of other conflicting variables. Changes in wind velocity, water depth, and size of point bars all contributed to these confounding variances. Combined with a comprehensive field campaign, SAR imagery interpretations have the potential to develop into a useful monitoring tool for monitoring Arctic rivers and developing resource

  4. Detecting methane ebullition in winter from Alaskan lakes using synthetic aperture radar remote sensing

    Science.gov (United States)

    Engram, Melanie J.

    Methane (CH4) is a greenhouse gas with a high radiative forcing attribute, yet large uncertainties remain in constraining atmospheric CH4 sources and sinks. While freshwater lakes are known atmospheric CH4 sources, flux through ebullition (bubbling) is difficult to quantify in situ due to uneven spatial distribution and temporally irregular gas eruptions. This heterogeneous distribution of CH4 ebullition also creates error when scaling up field measurements for flux estimations. This thesis reviews estimates of CH4 contribution to the atmosphere by freshwater lakes presented in current literature and identifies knowledge gaps and the logistical difficulties in sampling CH 4 flux via ebullition (bubbling). My research investigates various imaging parameters of space-borne synthetic aperture radar (SAR) to constrain current CH4 emissions from northern lakes. In a GIS spatial analysis of lakes on the northern Seward Peninsula, Alaska, comparing field data of ebullition to SAR, I found that SAR L-band backscatter from lake ice was high from lakes with CH4 bubbles trapped by lake ice and low from lakes with low ebullition activity. The 'roughness' component of a Pauli polarimetric decomposition of quad-pol SAR showed a significant correlation with the percentage of lake ice area containing CH4 bubbles and with CH4 ebullition flux. This indicates that the mechanism of SAR scattering from ebullition bubbles trapped by lake ice is single bounce. I conclude that SAR remote sensing could improve our ability to quantify lake ebullition at larger spatial scales than field measurements alone, could offer between-lake comparison of CH 4 ebullition activity, and is a potential tool for developing regional estimations of lake-source CH4.

  5. High-resolution nondestructive testing of multilayer dielectric materials using wideband microwave synthetic aperture radar imaging

    Science.gov (United States)

    Kim, Tae Hee; James, Robin; Narayanan, Ram M.

    2017-04-01

    Fiber Reinforced Polymer or Plastic (FRP) composites have been rapidly increasing in the aerospace, automotive and marine industry, and civil engineering, because these composites show superior characteristics such as outstanding strength and stiffness, low weight, as well as anti-corrosion and easy production. Generally, the advancement of materials calls for correspondingly advanced methods and technologies for inspection and failure detection during production or maintenance, especially in the area of nondestructive testing (NDT). Among numerous inspection techniques, microwave sensing methods can be effectively used for NDT of FRP composites. FRP composite materials can be produced using various structures and materials, and various defects or flaws occur due to environmental conditions encountered during operation. However, reliable, low-cost, and easy-to-operate NDT methods have not been developed and tested. FRP composites are usually produced as multilayered structures consisting of fiber plate, matrix and core. Therefore, typical defects appearing in FRP composites are disbondings, delaminations, object inclusions, and certain kinds of barely visible impact damages. In this paper, we propose a microwave NDT method, based on synthetic aperture radar (SAR) imaging algorithms, for stand-off imaging of internal delaminations. When a microwave signal is incident on a multilayer dielectric material, the reflected signal provides a good response to interfaces and transverse cracks. An electromagnetic wave model is introduced to delineate interface widths or defect depths from the reflected waves. For the purpose of numerical analysis and simulation, multilayered composite samples with various artificial defects are assumed, and their SAR images are obtained and analyzed using a variety of high-resolution wideband waveforms.

  6. Condition assessment of corroded steel rebar in free space using synthetic aperture radar images

    Science.gov (United States)

    Ingemi, Christopher M.; Owusu Twumasi, Jones; Litt, Swinderjit; Yu, Tzuyang

    2017-04-01

    Synthetic aperture radar (SAR) imaging of construction materials offers civil engineers an opportunity to better assess the condition of aging civil infrastructures such as reinforced concrete (RC) structures. Corrosion of steel rebar in RC structures is a major problem responsible for their premature failure and unexpected collapse. In this paper, SAR imaging is applied to the quantitative assessment of corroded steel rebar in free space as the first step toward the use of SAR imaging for subsurface sensing of aging RC structures. A 10 GHz stripmap SAR system was used inside an anechoic chamber. The bandwidth of the radar system was 1.5 GHz. Steel rebar specimens were artificially corroded to different levels by regularly applying a mist of 5% NaCl solution for different durations of time in order to simulate the condition of natural corrosion. Two sizes (No. 3 and No. 4) of steel rebar were used in this research. Different orientations of steel rebar were considered. Corrosion level was determined by measuring the mass loss of corroded steel rebar specimens. From our results, feasibility of SAR images for the condition assessment of corroded steel rebar was experimentally demonstrated. It was found that the presence of surface rust on corroded steel rebar reduces the amplitude in SAR images. The SAR image of corroded steel rebar also exhibited a distribution of SAR amplitudes different from the one of intact steel rebar. In addition, it was also found that there is an optimal range for the condition assessment of corroded steel rebar in free space. In our experiment, the optimal range was determined to be 30.4 cm.

  7. Hydrologic modeling of Guinale River Basin using HEC-HMS and synthetic aperture radar

    Science.gov (United States)

    Bien, Ferdinand E.; Plopenio, Joanaviva C.

    2017-09-01

    This paper presents the methods and results of hydrologic modeling of Guinale river basin through the use of HEC-HMS software and Synthetic Aperture Radar Digital Elevation Model (SAR DEM). Guinale River Basin is located in the province of Albay, Philippines which is one of the river basins covered by the Ateneo de Naga University (ADNU) Phil-LiDAR 1. This research project was funded by the Department of Science and Technology (DOST) through the Philippine Council for Industry, Energy and Emerging Technology Research and Development (PCIEERD). Its objectives are to simulate the hydrologic model of Guinale River basin using HEC-HMS software and SAR DEM. Its basin covers an area of 165.395 sq.km. and the hydrologic model was calibrated using the storm event typhoon Nona (international name Melor). Its parameter had undergone a series of optimization processes of HEC-HMS software in order to produce an acceptable level of model efficiency. The Nash-Sutcliffe (E), Percent Bias and Standard Deviation Ratio were used to measure the model efficiency, giving values of 0.880, 0.260 and 0.346 respectively which resulted to a "very good" performance rating of the model. The flood inundation model was simulated using Legazpi Rainfall Intensity Duration Frequency Curves (RIDF) and HEC-RAS software developed by the US Army corps of Engineers (USACE). This hydrologic model will provide the Municipal Disaster Risk Reduction Management Office (MDRRMO), Local Government units (LGUs) and the community a tool for the prediction of runoff in the area.

  8. 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.

  9. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    Science.gov (United States)

    Villagómez-Hoyos, Carlos A.; Stuart, Matthias B.; Bechsgaard, Thor; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow angle in the ROI was 86.22° +/- 6.66° with a true flow angle of 90°. A relative velocity bias of -39% with a standard deviation of 13% was found. In-vivo acquisitions show complex flow patterns in the heart. In the aortic valve view, blood is seen exiting the left ventricle cavity through the aortic valve into the aorta during the systolic phase of the cardiac cycle. In the left ventricle view, blood flow is seen entering the left ventricle cavity through the mitral valve and splitting in two ways when approximating the left ventricle wall. The work presents 2-D velocity estimates on the heart from a non-invasive transthoracic scan. The ability of the method detecting flow regardless of the beam angle could potentially reveal a more complete view of the flow patterns presented on the heart.

  10. Developing an Automated Machine Learning Marine Oil Spill Detection System with Synthetic Aperture Radar

    Science.gov (United States)

    Pinales, J. C.; Graber, H. C.; Hargrove, J. T.; Caruso, M. J.

    2016-02-01

    Previous studies have demonstrated the ability to detect and classify marine hydrocarbon films with spaceborne synthetic aperture radar (SAR) imagery. The dampening effects of hydrocarbon discharges on small surface capillary-gravity waves renders the ocean surface "radar dark" compared with the standard wind-borne ocean surfaces. Given the scope and impact of events like the Deepwater Horizon oil spill, the need for improved, automated and expedient monitoring of hydrocarbon-related marine anomalies has become a pressing and complex issue for governments and the extraction industry. The research presented here describes the development, training, and utilization of an algorithm that detects marine oil spills in an automated, semi-supervised manner, utilizing X-, C-, or L-band SAR data as the primary input. Ancillary datasets include related radar-borne variables (incidence angle, etc.), environmental data (wind speed, etc.) and textural descriptors. Shapefiles produced by an experienced human-analyst served as targets (validation) during the training portion of the investigation. Training and testing datasets were chosen for development and assessment of algorithm effectiveness as well as optimal conditions for oil detection in SAR data. The algorithm detects oil spills by following a 3-step methodology: object detection, feature extraction, and classification. Previous oil spill detection and classification methodologies such as machine learning algorithms, artificial neural networks (ANN), and multivariate classification methods like partial least squares-discriminant analysis (PLS-DA) are evaluated and compared. Statistical, transform, and model-based image texture techniques, commonly used for object mapping directly or as inputs for more complex methodologies, are explored to determine optimal textures for an oil spill detection system. The influence of the ancillary variables is explored, with a particular focus on the role of strong vs. weak wind forcing.

  11. Improved synthetic aperture focusing technique results of thick concrete specimens through frequency banding

    Science.gov (United States)

    Clayton, Dwight; Barker, Alan; Albright, Austin; Santos-Villalobos, Hector

    2016-02-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on ultrasonic data collected from thick, complex concrete structures such as in NPPs. Towards these goals, we apply the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band's interaction with the contents of the concrete structure. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To minimize artifacts caused by boundary effects, the dimensions of the specimens should not be too compact. In this paper, we apply this enhanced SAFT technique to a 2.134 m × 2.134 m × 1.016 m concrete

  12. The Benefits of Using Time-Frequency Analysis with Synthetic Aperture Focusing Technique

    Energy Technology Data Exchange (ETDEWEB)

    Albright, Austin P [ORNL; Clayton, Dwight A [ORNL

    2015-01-01

    Improvements in detection and resolution are always desired and needed. There are various instruments available for the inspection of concrete structures that can be used with confidence for detecting different defects. However, more often than not that confidence is heavily dependent on the experience of the operator rather than the clear, objective discernibility of the output of the instrument. The challenge of objective discernment is amplified when the concrete structures contain multiple layers of reinforcement, are of significant thickness, or both, such as concrete structures in nuclear power plants. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on data collected from thick, complex concrete structures. A secondary goal is to improve existing SAFT results, with regards to repeatedly and objectively identifying defects and/or internal structure of concrete structures. Towards these goals, we are applying the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band s interaction with the contents of the concrete structure. We apply our technique to data sets collected using a commercial, ultrasonic linear array (MIRA) from two 1.5m x 2m x 25cm concrete test specimens. One specimen contains multiple layers of rebar. The other contains honeycomb, crack, and rebar bonding defect analogs. This approach opens up a multitude of possibilities for improved detection, readability, and overall improved objectivity. We will focus on

  13. The benefits of using time-frequency analysis with synthetic aperture focusing technique

    Energy Technology Data Exchange (ETDEWEB)

    Albright, Austin, E-mail: albrightap@ornl.gov, E-mail: claytonda@ornl.gov; Clayton, Dwight, E-mail: albrightap@ornl.gov, E-mail: claytonda@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States)

    2015-03-31

    Improvements in detection and resolution are always desired and needed. There are various instruments available for the inspection of concrete structures that can be used with confidence for detecting different defects. However, more often than not that confidence is heavily dependent on the experience of the operator rather than the clear, objective discernibility of the output of the instrument. The challenge of objective discernment is amplified when the concrete structures contain multiple layers of reinforcement, are of significant thickness, or both, such as concrete structures in nuclear power plants. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on data collected from thick, complex concrete structures. A secondary goal is to improve existing SAFT results, with regards to repeatedly and objectively identifying defects and/or internal structure of concrete structures. Towards these goals, we are applying the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band's interaction with the contents of the concrete structure. We apply our technique to data sets collected using a commercial, ultrasonic linear array (MIRA) from two 1.5m × 2m × 25cm concrete test specimens. One specimen contains multiple layers of rebar. The other contains honeycomb, crack, and rebar bonding defect analogs. This approach opens up a multitude of possibilities for improved detection, readability, and overall improved objectivity. We will focus on

  14. The benefits of using time-frequency analysis with synthetic aperture focusing technique

    Science.gov (United States)

    Albright, Austin; Clayton, Dwight

    2015-03-01

    Improvements in detection and resolution are always desired and needed. There are various instruments available for the inspection of concrete structures that can be used with confidence for detecting different defects. However, more often than not that confidence is heavily dependent on the experience of the operator rather than the clear, objective discernibility of the output of the instrument. The challenge of objective discernment is amplified when the concrete structures contain multiple layers of reinforcement, are of significant thickness, or both, such as concrete structures in nuclear power plants. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on data collected from thick, complex concrete structures. A secondary goal is to improve existing SAFT results, with regards to repeatedly and objectively identifying defects and/or internal structure of concrete structures. Towards these goals, we are applying the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band's interaction with the contents of the concrete structure. We apply our technique to data sets collected using a commercial, ultrasonic linear array (MIRA) from two 1.5m × 2m × 25cm concrete test specimens. One specimen contains multiple layers of rebar. The other contains honeycomb, crack, and rebar bonding defect analogs. This approach opens up a multitude of possibilities for improved detection, readability, and overall improved objectivity. We will focus on

  15. Toward dynamic lumbar punctures guidance based on single element synthetic tracked aperture ultrasound imaging

    Science.gov (United States)

    Zhang, Haichong K.; Lin, Melissa; Kim, Younsu; Paredes, Mateo; Kannan, Karun; Patel, Nisu; Moghekar, Abhay; Durr, Nicholas J.; Boctor, Emad M.

    2017-03-01

    Lumbar punctures (LPs) are interventional procedures used to collect cerebrospinal fluid (CSF), a bodily fluid needed to diagnose central nervous system disorders. Most lumbar punctures are performed blindly without imaging guidance. Because the target window is small, physicians can only accurately palpate the appropriate space about 30% of the time and perform a successful procedure after an average of three attempts. Although various forms of imaging based guidance systems have been developed to aid in this procedure, these systems complicate the procedure by including independent image modalities and requiring image-to-needle registration to guide the needle insertion. Here, we propose a simple and direct needle insertion platform utilizing a single ultrasound element within the needle through dynamic sensing and imaging. The needle-shaped ultrasound transducer can not only sense the distance between the tip and a potential obstacle such as bone, but also visually locate structures by combining transducer location tracking and back projection based tracked synthetic aperture beam-forming algorithm. The concept of the system was validated through simulation first, which revealed the tolerance to realistic error. Then, the initial prototype of the single element transducer was built into a 14G needle, and was mounted on a holster equipped with a rotation tracking encoder. We experimentally evaluated the system using a metal wire phantom mimicking high reflection bone structures and an actual spine bone phantom with both the controlled motion and freehand scanning. An ultrasound image corresponding to the model phantom structure was reconstructed using the beam-forming algorithm, and the resolution was improved compared to without beam-forming. These results demonstrated the proposed system has the potential to be used as an ultrasound imaging system for lumbar puncture procedures.

  16. Detection and quantification of precipitations signatures on synthetic aperture radar imagery at X band

    Science.gov (United States)

    Mori, Saverio; Montopoli, Mario; Pulvirenti, Luca; Marzano, Frank S.; Pierdicca, Nazzareno

    2016-10-01

    Nowadays a well-established tool for Earth remote sensing is represented by Spaceborne synthetic aperture radars (SARs) operating at L-band and above that offers a microwave perspective at very high spatial resolution in almost all-weather conditions. Nevertheless, atmospheric precipitating clouds can significantly affect the signal backscattered from the ground surface on both amplitude and phase, as assessed by numerous recent works analyzing data collected by COSMO-SkyMed (CSK) and TerraSAR-X (TSX) missions. On the other hand, such sensitivity could allow detecting and quantifying precipitations through SARs. In this work, we propose an innovative processing framework aiming at producing X-SARs precipitation maps and cloud masks. While clouds masks allow the user to detect areas interested by precipitations, precipitation maps offer the unique opportunity to ingest within flood forecasting model precipitation data at the catchment scale. Indeed, several issues still need to be fully addressed. The proposed approach allows distinguishing flooded areas, precipitating clouds together with permanent water bodies. The detection procedure uses image segmentation techniques, fuzzy logic and ancillary data such as local incident angle map and land cover; an improved regression empirical algorithm gives the precipitation estimation. We have applied the proposed methodology to 16 study cases, acquired within TSX and CSK missions over Italy and United States. This choice allows analysing different typologies of events, and verifying the proposed methodology through the available local weather radar networks. In this work, we will discuss the results obtained until now in terms of improved rain cell localization and precipitation quantification.

  17. Preliminary inter-model comparison of the Agulhas current with direct range doppler velocity estimates from Envisat's Advanced Synthetic Aperture Radar (ASAR)

    CSIR Research Space (South Africa)

    Backeberg, Bjorn C

    2010-07-01

    Full Text Available is of great importance. In this paper we compare direct surface velocity estimates from Envisat's Advanced Synthetic Aperture Radar with surface velocity fields obtained from two different ocean numerical models. In particular, we focus on the models...

  18. Land cover classification accuracy from electro-optical, X, C, and L-band Synthetic Aperture Radar data fusion

    Science.gov (United States)

    Hammann, Mark Gregory

    The fusion of electro-optical (EO) multi-spectral satellite imagery with Synthetic Aperture Radar (SAR) data was explored with the working hypothesis that the addition of multi-band SAR will increase the land-cover (LC) classification accuracy compared to EO alone. Three satellite sources for SAR imagery were used: X-band from TerraSAR-X, C-band from RADARSAT-2, and L-band from PALSAR. Images from the RapidEye satellites were the source of the EO imagery. Imagery from the GeoEye-1 and WorldView-2 satellites aided the selection of ground truth. Three study areas were chosen: Wad Medani, Sudan; Campinas, Brazil; and Fresno- Kings Counties, USA. EO imagery were radiometrically calibrated, atmospherically compensated, orthorectifed, co-registered, and clipped to a common area of interest (AOI). SAR imagery were radiometrically calibrated, and geometrically corrected for terrain and incidence angle by converting to ground range and Sigma Naught (?0). The original SAR HH data were included in the fused image stack after despeckling with a 3x3 Enhanced Lee filter. The variance and Gray-Level-Co-occurrence Matrix (GLCM) texture measures of contrast, entropy, and correlation were derived from the non-despeckled SAR HH bands. Data fusion was done with layer stacking and all data were resampled to a common spatial resolution. The Support Vector Machine (SVM) decision rule was used for the supervised classifications. Similar LC classes were identified and tested for each study area. For Wad Medani, nine classes were tested: low and medium intensity urban, sparse forest, water, barren ground, and four agriculture classes (fallow, bare agricultural ground, green crops, and orchards). For Campinas, Brazil, five generic classes were tested: urban, agriculture, forest, water, and barren ground. For the Fresno-Kings Counties location 11 classes were studied: three generic classes (urban, water, barren land), and eight specific crops. In all cases the addition of SAR to EO resulted

  19. 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

  20. Oil Spill Detection and Tracking Using Lipschitz Regularity and Multiscale Techniques in Synthetic Aperture Radar Imagery

    Science.gov (United States)

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

    2014-12-01

    Automatic oil spill detection and tracking from Synthetic Aperture Radar (SAR) images is a difficult task, due in large part to the inhomogeneous properties of the sea surface, the high level of speckle inherent in SAR data, the complexity and the highly non-Gaussian nature of amplitude information, and the low temporal sampling that is often achieved with SAR systems. This research presents a promising new oil spill detection and tracking method that is based on time series of SAR images. Through the combination of a number of advanced image processing techniques, the develop approach is able to mitigate some of these previously mentioned limitations of SAR-based oil-spill detection and enables fully automatic spill detection and tracking across a wide range of spatial scales. The method combines an initial automatic texture analysis with a consecutive change detection approach based on multi-scale image decomposition. The first step of the approach, a texture transformation of the original SAR images, is performed in order to normalize the ocean background and enhance the contrast between oil-covered and oil-free ocean surfaces. The Lipschitz regularity (LR), a local texture parameter, is used here due to its proven ability to normalize the reflectivity properties of ocean water and maximize the visibly of oil in water. To calculate LR, the images are decomposed using two-dimensional continuous wavelet transform (2D-CWT), and transformed into Holder space to measure LR. After texture transformation, the now normalized images are inserted into our multi-temporal change detection algorithm. The multi-temporal change detection approach is a two-step procedure including (1) data enhancement and filtering and (2) multi-scale automatic change detection. The performance of the developed approach is demonstrated by an application to oil spill areas in the Gulf of Mexico. In this example, areas affected by oil spills were identified from a series of ALOS PALSAR images

  1. 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

  2. A Vector Flow Imaging Method for Portable Ultrasound Using Synthetic Aperture Sequential Beamforming.

    Science.gov (United States)

    Di Ianni, Tommaso; Villagomez Hoyos, Carlos Armando; Ewertsen, Caroline; Kjeldsen, Thomas Kim; Mosegaard, Jesper; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

    2017-11-01

    This paper presents a vector flow imaging method for the integration of quantitative blood flow imaging in portable ultrasound systems. The method combines directional transverse oscillation (TO) and synthetic aperture sequential beamforming to yield continuous velocity estimation in the whole imaging region. Six focused emissions are used to create a high-resolution image (HRI), and a dual-stage beamforming approach is used to lower the data throughput between the probe and the processing unit. The transmit/receive focal points are laterally separated to obtain a TO in the HRI that allows for the velocity estimation along the lateral and axial directions using a phase-shift estimator. The performance of the method was investigated with constant flow measurements in a flow rig system using the SARUS scanner and a 4.1-MHz linear array. A sequence was designed with interleaved B-mode and flow emissions to obtain continuous data acquisition. A parametric study was carried out to evaluate the effect of critical parameters. The vessel was placed at depths from 20 to 40 mm, with beam-to-flow angles of 65°, 75°, and 90°. For the lateral velocities at 20 mm, a bias between -5% and -6.2% was obtained, and the standard deviation (SD) was between 6% and 9.6%. The axial bias was lower than 1% with an SD around 2%. The mean estimated angles were 66.70° ± 2.86°, 72.65° ± 2.48°, and 89.13° ± 0.79° for the three cases. A proof-of-concept demonstration of the real-time processing and wireless transmission was tested in a commercial tablet obtaining a frame rate of 27 frames/s and a data rate of 14 MB/s. An in vivo measurement of a common carotid artery of a healthy volunteer was finally performed to show the potential of the method in a realistic setting. The relative SD averaged over a cardiac cycle was 4.33%.

  3. Surface Water Detection Using Fused Synthetic Aperture Radar, Airborne LiDAR and Optical Imagery

    Science.gov (United States)

    Braun, A.; Irwin, K.; Beaulne, D.; Fotopoulos, G.; Lougheed, S. C.

    2016-12-01

    Each remote sensing technique has its unique set of strengths and weaknesses, but by combining techniques the classification accuracy can be increased. The goal of this project is to underline the strengths and weaknesses of Synthetic Aperture Radar (SAR), LiDAR and optical imagery data and highlight the opportunities where integration of the three data types can increase the accuracy of identifying water in a principally natural landscape. The study area is located at the Queen's University Biological Station, Ontario, Canada. TerraSAR-X (TSX) data was acquired between April and July 2016, consisting of four single polarization (HH) staring spotlight mode backscatter intensity images. Grey-level thresholding is used to extract surface water bodies, before identifying and masking zones of radar shadow and layover by using LiDAR elevation models to estimate the canopy height and applying simple geometry algorithms. The airborne LiDAR survey was conducted in June 2014, resulting in a discrete return dataset with a density of 1 point/m2. Radiometric calibration to correct for range and incidence angle is applied, before classifying the points as water or land based on corrected intensity, elevation, roughness, and intensity density. Panchromatic and multispectral (4-band) imagery from Quickbird was collected in September 2005 at spatial resolutions of 0.6m and 2.5m respectively. Pixel-based classification is applied to identify and distinguish water bodies from land. A classification system which inputs SAR-, LiDAR- and optically-derived water presence models in raster formats is developed to exploit the strengths and weaknesses of each technique. The total percentage of water detected in the sample area for SAR backscatter, LiDAR intensity, and optical imagery was 27%, 19% and 18% respectively. The output matrix of the classification system indicates that in over 72% of the study area all three methods agree on the classification. Analysis was specifically targeted

  4. Mapping Surface Soil Moisture With Synthetic Aperture Radar Data and Basin Indexes

    Science.gov (United States)

    Yilmaz, M.; Sorman, A.; Sorman, U.

    2008-12-01

    The soil moisture condition of a watershed plays a significant role in separation of infiltration and surface runoff, and hence is a key parameter for the majority of physical hydrological models. Due to the large difference in dielectric constants of dry soil and water, microwave remote sensing (particularly the commonly available synthetic aperture radar) is a potential tool for such studies. The main aim of this study is to compute a distributed soil moisture map of a catchment, which can be input to a hydrological model. For this purpose, nine field trips are performed and point surface soil moisture values are collected with a Time Domain Reflectometer. The field studies, which are carried out on a small catchment in western Anatolia, are planned to match radar image acquisitions and accomplished over a water year. First, the Dubois Model, a physical backscatter model is utilized in the reverse order to compute soil surface roughness values. This is accomplished for the field study dates which have two radar image acquisitions and with sparse vegetation cover. Then the first relationship of this study, between observed radar backscatter values and computed roughness values, is established with a correlation coefficient of 0.78. For bare soil surfaces, local incidence angle, soil moisture and roughness are the most dominant parameters effecting radar backscatter. After computing the incidence angle map of the study area, the second relationship, between observed radar backscatter values and the three governing parameters, is determined with a correlation coefficient of 0.87. The third and the last relationship of the study is estimated between the measured point soil moisture values and two basin indexes; topographic and solar radiation. In the last part of the study, the established three relationships, which are derived for point moisture measurements, are used to compute the soil moisture map of the whole catchment. This process is handled separately for the

  5. Depth-of-field enhancement in Filtered-Delay Multiply and Sum beamformed images using Synthetic Aperture Focusing.

    Science.gov (United States)

    Matrone, Giulia; Savoia, Alessandro Stuart; Caliano, Giosuè; Magenes, Giovanni

    2017-03-01

    The Synthetic Aperture Focusing (SAF) technique makes it possible to achieve a higher and more uniform quality of ultrasound images throughout depth, as if both transmit and receive dynamic focusing were applied. In this work we combine a particular implementation of SAF, called Synthetic Transmit Aperture (STA) technique, in which a single element in turn transmits and all the array elements receive the ultrasound wave, with the Filtered-Delay Multiply and Sum (F-DMAS) non-linear beamforming algorithm that we presented in a previous paper. We show that using F-DMAS, which is based on a measure of backscattered signal spatial correlation, B-mode images have a higher contrast resolution but suffer from a loss of brightness away from the transmit focus, when a classical scan with receive-only dynamic focusing is performed. On the other hand, when synthetic transmit focusing is achieved by implementing STA, such a loss is compensated for and a higher depth of field is obtained, as signal coherence improves. A drawback of SAF/STA however is the reduced signal-to-noise ratio, due to single-element transmission; in the paper we also analyze how this influences F-DMAS images. Finally, a preliminary investigation on the use of the classical monostatic SAF technique with F-DMAS beamforming is also carried out to evaluate its potential performances. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Inspection Of Spray On Foam Insulation (SOFI) Using and Microwave and Millimeter Wave Synthetic Aperture Focusing and Holography

    Science.gov (United States)

    Hepburn, F. L.; Case, J. T.; Zoughi, R.

    2006-01-01

    The Space Shuttle Columbia's catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking the left wing of the orbiter causing significant damage to some of the reinforced carbon/carbon leading edge wing panels [1]. Microwave and millimeter wave nondestructive evaluation methods have shown great potential for inspecting SOFI for the purpose of detecting anomalies such as small air voids that may cause separation of the SOFI from the external tank during a launch [2,3]. These methods are capable of producing relatively high-resolution images of the interior of SOFI. Although effective, there are some advantages in using synthetic focusing methods as opposed to real focusing methods such as reduced probe size, the ability to determine depth from multiple views, and the ability to slice images due to sufficient range resolution. To this end, synthetic aperture focusing techniques (SAFT) were first pursued for this purpose and later wide-band microwave holography was implemented [4-7]. This paper presents the results of this investigation using frequency domain synthetic aperture focusing technique (FD-SAFT) and wide-band microwave holography methods illustrating their potential capabilities for inspecting the space shuttle's SOFI at millimeter wave frequencies.

  7. Satellite reconnaissance

    Science.gov (United States)

    Deloor, G. P.

    1984-06-01

    The potential of the observation equipment in remote sensing satellites is described. United States meteorology, land use and oceanography satellites and the major US Earth observation programs are listed. Imaging satellite systems are described such as: visible light and near infrared, thermal IR window, and microwave window. It is concluded that a geometrical resolution between 10 and 40 m can be expected. In order to reduce the data flow from the satellite system the input side of the system (the object-sensor interaction) has to be known. Satellites with synthetic aperture radar are increasingly important, but satellites can never fully replace observations with aircraft and drones.

  8. 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, Charles; 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.

  9. Integrating gravimetric and interferometric synthetic aperture radar data for enhancing reservoir history matching of carbonate gas and volatile oil reservoirs

    KAUST Repository

    Katterbauer, Klemens

    2016-08-25

    Reservoir history matching is assuming a critical role in understanding reservoir characteristics, tracking water fronts, and forecasting production. While production data have been incorporated for matching reservoir production levels and estimating critical reservoir parameters, the sparse spatial nature of this dataset limits the efficiency of the history matching process. Recently, gravimetry techniques have significantly advanced to the point of providing measurement accuracy in the microgal range and consequently can be used for the tracking of gas displacement caused by water influx. While gravity measurements provide information on subsurface density changes, i.e., the composition of the reservoir, these data do only yield marginal information about temporal displacements of oil and inflowing water. We propose to complement gravimetric data with interferometric synthetic aperture radar surface deformation data to exploit the strong pressure deformation relationship for enhancing fluid flow direction forecasts. We have developed an ensemble Kalman-filter-based history matching framework for gas, gas condensate, and volatile oil reservoirs, which synergizes time-lapse gravity and interferometric synthetic aperture radar data for improved reservoir management and reservoir forecasts. Based on a dual state-parameter estimation algorithm separating the estimation of static reservoir parameters from the dynamic reservoir parameters, our numerical experiments demonstrate that history matching gravity measurements allow monitoring the density changes caused by oil-gas phase transition and water influx to determine the saturation levels, whereas the interferometric synthetic aperture radar measurements help to improve the forecasts of hydrocarbon production and water displacement directions. The reservoir estimates resulting from the dual filtering scheme are on average 20%-40% better than those from the joint estimation scheme, but require about a 30% increase in

  10. 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.

  11. Characterization of L-band synthetic aperture radar (SAR) backscatter from floating and grounded thermokarst lake ice in Arctic Alaska

    OpenAIRE

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

    2013-01-01

    Radar remote sensing is a well-established method to discriminate lakes retaining liquid-phase water beneath winter ice cover from those that do not. L-band (23.6 cm wavelength) airborne radar showed great promise in the 1970s, but spaceborne synthetic aperture radar (SAR) studies have focused on C-band (5.6 cm) SAR to classify lake ice with no further attention to L-band SAR for this purpose. Here, we examined calibrated L-band single- and quadrature-polarized SAR returns f...

  12. Detection and sizing of stress corrosion cracks in austenitic components using ultrasonic testing and synthetic aperture focusing technique

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, Sandra; Wagner, Sabine [Stuttgart Univ. (Germany). Materialpruefungsanstalt; Dillhoefer, Alexander [NDT Global GmbH and Co.KG, Stutensee (Germany); Rieder, Hans; Spies, Martin [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren (IZFP), Saarbruecken (Germany)

    2015-05-01

    Flaw detection and sizing using NDT techniques is an important factor for reliably assessing the integrity of components. In the case of dissimilar metal welds and austenitic stainless steel welds, the grain structure of the weld in combination with the elastic anisotropy of the material will present major challenges for UT. A study on austenitic base metal test blocks with artificially grown IGSCCs has shown that the Synthetic Aperture Focusing Technique (SAFT) can improve the signal-to-noise ratio, particularly for crack tip signals. In welded test blocks, the influence of the inhomogeneous, anisotropic weld has to be considered.

  13. On the retrieval of significant wave heights from spaceborne Synthetic Aperture Radar (ERS-SAR using the Max-Planck Institut (MPI algorithm

    Directory of Open Access Journals (Sweden)

    Violante-Carvalho Nelson

    2005-01-01

    Full Text Available Synthetic Aperture Radar (SAR onboard satellites is the only source of directional wave spectra with continuous and global coverage. Millions of SAR Wave Mode (SWM imagettes have been acquired since the launch in the early 1990's of the first European Remote Sensing Satellite ERS-1 and its successors ERS-2 and ENVISAT, which has opened up many possibilities specially for wave data assimilation purposes. The main aim of data assimilation is to improve the forecasting introducing available observations into the modeling procedures in order to minimize the differences between model estimates and measurements. However there are limitations in the retrieval of the directional spectrum from SAR images due to nonlinearities in the mapping mechanism. The Max-Planck Institut (MPI scheme, the first proposed and most widely used algorithm to retrieve directional wave spectra from SAR images, is employed to compare significant wave heights retrieved from ERS-1 SAR against buoy measurements and against the WAM wave model. It is shown that for periods shorter than 12 seconds the WAM model performs better than the MPI, despite the fact that the model is used as first guess to the MPI method, that is the retrieval is deteriorating the first guess. For periods longer than 12 seconds, the part of the spectrum that is directly measured by SAR, the performance of the MPI scheme is at least as good as the WAM model.

  14. Synthetic Aperture Radiometry Evaluated by a Two-Channel Demonstration Model

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1998-01-01

    by interferometric measurements using the antenna elements in pairs, followed by an image reconstruction based on an inverse Fourier transform, results in an imaging instrument without the need of mechanical scan. The thinned aperture and the nonscanning feature make the technique attractive for spaceborne...... of the system is that it uses a focused antenna system, thus enabling a short distance to the target. Set still utilizing image reconstruction algorithms identical to those used in a normal far-field situation. The aperture synthesis theory is discussed, with special emphasis on focused systems; the radiometer...

  15. Advanced Communication Technology Satellite (ACTS) Very Small Aperture Terminal (VSAT) Network Control Performance

    Science.gov (United States)

    Coney, T. A.

    1996-01-01

    This paper discusses the performance of the network control function for the Advanced Communications Technology Satellite (ACTS) very small aperture terminal (VSAT) full mesh network. This includes control of all operational activities such as acquisition, synchronization, timing and rain fade compensation as well as control of all communications activities such as on-demand integrated services (voice, video, and date) connects and disconnects Operations control is provided by an in-band orderwire carried in the baseboard processor (BBP) control burst, the orderwire burst, the reference burst, and the uplink traffic burst. Communication services are provided by demand assigned multiple access (DAMA) protocols. The ACTS implementation of DAMA protocols ensures both on-demand and integrated voice, video and data services. Communications services control is also provided by the in-band orderwire but uses only the reference burst and the uplink traffic burst. The performance of the ACTS network control functions have been successfully tested during on-orbit checkout and in various VSAT networks in day to day operations. This paper discusses the network operations and services control performance.

  16. Inspection of Spray on Foam Insulation (SOFI) Using Microwave and Millimeter Wave Synthetic Aperture Focusing and Holography

    Science.gov (United States)

    Case, J. T.; Hepburn, F. L.; Zoughi, R.

    2006-01-01

    The Space Shuttle Columbia s catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking and significantly damaging the left wing of the orbiter, which may have been due to a flawed section of SOFI. Microwave and millimeter wave nondestructive evaluation (NDE) methods have shown great potential detecting anomalies in SOFI such as small air voids using a horn and lens in a (real) focused configuration. Synthetic focusing methods may also be used to detect air voids in SOFI and may additionally offer the ability to locate the defect in three dimensions. To this end, two different methods were investigated; namely, frequency domain synthetic aperture focusing technique (FD-SAFT) and wide-band microwave holography. To illustrate the performance of these methods they were applied to two different SOFI samples. The results of these investigations demonstrate the capabilities of these methods for SOFI inspection.

  17. 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

  18. Implementation of synthetic aperture imaging on a hand-held device

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Kjeldsen, Thomas; Larsen, Lee

    2014-01-01

    This paper presents several implementations of Syn- thetic Aperture Sequential Beamforming (SASB) on commer- cially available hand-held devices. The implementations include real-time wireless reception of ultrasound radio frequency sig- nals and GPU processing for B-mode imaging. The proposed imp...

  19. Characterization and discrimination of evolving mineral and plant oil slicks based on L-band synthetic aperture radar (SAR)

    Science.gov (United States)

    Jones, Cathleen E.; Espeseth, Martine M.; Holt, Benjamin; Brekke, Camilla; Skrunes, Stine

    2016-10-01

    Evolution of the damping ratio for Bragg wavenumbers in the range 32-43 rad/m is evaluated for oil slicks of different composition released in the open ocean and allowed to develop naturally. The study uses quad-polarimetric L-band airborne synthetic aperture radar data acquired over three mineral oil emulsion releases of different, known oil-to-water ratio, and a near-coincident release of 2-ethylhexyl oleate that served as a biogenic look-alike. The experiment occurred during the 2015 Norwegian oil-on-water exercise in the North Sea during a period of relatively high winds ( 12 m/s). NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) was used to repeatedly image the slicks over a period of eight hours, capturing the slicks' early development and providing a time series from which to track the evolution of the slicks' size, position, and radiometric characteristics. Particular emphasis is given in this analysis to identification of zones of higher damping ratio within the slicks (zoning) as potential indicators of thicker oil, and to comparison of the evolution of emulsion and plant oil damping ratios. It was found that all mineral oil slicks initially exhibited zoning apparent in VV, HH, and HV intensities, and that the areas of higher damping ratio persisted the longest for the highest oil content emulsion (80% oil by volume). In contrast, zoning was not unambiguously evident for plant oil at any time from 44 minutes to 8.5 hours after release.

  20. The Galápagos Islands seen from space: the contribution of Synthetic Aperture Radar Interferometry (InSAR) to volcano monitoring

    Science.gov (United States)

    Osmanoglu, B.; Baker, S.; Bagnardi, M.; Amelung, F.

    2010-12-01

    Although the Galápagos volcanoes are some of the most active volcanoes on Earth, because of their geographic isolation and the difficult working conditions they have been virtually unmonitored by geodetic methods until the last 18 years. The use of detailed Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface deformation provides a unique opportunity to study magmatic processes in such a location. The phase difference (interferogram) of SAR images pairs for the same area acquired at different times, provides measurements of the ground deformation along the radar line-of-sight (LOS) with centimeter to millimeter accuracy. We use SAR data acquired over the Galápagos by the European Space Agency satellites ERS-1, ERS-2, ENVISAT and by the Canadian Space Agency satellite Radarsat-1, between 1992 and 2010. In order to obtain the temporal evolution of ground deformation at each volcano, we use the selected dataset and we apply the Small Baseline Subset (SBAS) method. We present SBAS displacement time-series for Wolf, Darwin, Fernandina, Alcedo, Sierra Negra and Cerro Azul, showing that all the six volcanoes that forms Fernandina and Isabela Islands have been actively deforming during the last eighteen years. We also identify and constrain some of the sources that generate the observed surface deformation by performing non-linear inversions in a homogeneous, isotropic, elastic half-space. With the frequent acquisitions of the ENVISAT satellite, we are able to study the evolution of the latest eruptions at Cerro Azul in 2008 and at Fernandina in 2009.

  1. Precipitation evidences on X-Band Synthetic Aperture Radar imagery: an approach for quantitative detection and estimation

    Science.gov (United States)

    Mori, Saverio; Marzano, Frank S.; Montopoli, Mario; Pulvirenti, Luca; Pierdicca, Nazzareno

    2017-04-01

    Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-established tool for Earth remote sensing; among the numerous civil applications we can indicate flood areas detection and monitoring, earthquakes analysis, digital elevation model production, land use monitoring and classification. Appealing characteristics of this kind of instruments is the high spatial resolution ensured in almost all-weather conditions and with a reasonable duty cycle and coverage. This result has achieved by the by the most recent generation of SAR missions, which moreover allow polarimetric observation of the target. Nevertheless, atmospheric clouds, in particular the precipitating ones, can significantly affect the signal backscattered from the ground surface (e.g. Ferrazzoli and Schiavon, 1997), on both amplitude and phase, with effects increasing with the operating frequency. In this respect, proofs are given by several recent works (e.g. Marzano et al., 2010, Baldini et al., 2014) using X-Band SAR data by COSMO-SkyMed (CSK) and TerraSAR-X (TSX) missions. On the other hand, this sensitivity open interesting perspectives towards the SAR observation, and eventually quantification, of precipitations. In this respect, a proposal approach for X-SARs precipitation maps production and cloud masking arise from our work. Cloud masking allows detection of precipitation compromised areas. Respect precipitation maps, satellite X-SARs offer the unique possibility to ingest within flood forecasting model precipitation data at the catchment scale. This aspect is particularly innovative, even if work has been done the late years, and some aspects need to still address. Our developed processing framework allows, within the cloud masking stage, distinguishing flooded areas, precipitating clouds together with permanent water bodies, all appearing dark in the SAR image. The procedure is mainly based on image segmentation techniques and fuzzy logic (e.g. Pulvirenti et

  2. Advanced 3-D Ultrasound Imaging: 3-D Synthetic Aperture Imaging using Fully Addressed and Row-Column Addressed 2-D Transducer Arrays

    DEFF Research Database (Denmark)

    Bouzari, Hamed

    because synthetic aperture imaging removes the limitation of a fixed transmit focal depth and instead enables dynamic transmit focusing. Particularly, synthetic aperture imaging could increase the achievable volume rate compared with parallel beamforming, to almost 50 times. Lately, the major ultrasound...... companies have produced ultrasound scanners using 2-D transducer arrays with enough transducer elements to produce high quality 3-D images. Because of the large matrix transducers with integrated custom electronics, these systems are extremely expensive. The relatively low price of ultrasound scanners...

  3. Two-beam-coupling correlator for synthetic aperture radar image recognition with power-law scattering centers preenhancement.

    Science.gov (United States)

    Haji-Saeed, Bahareh; Woods, Charles L; Kierstead, John; Khoury, Jed

    2008-06-01

    Synthetic radar image recognition is an area of interest for military applications including automatic target recognition, air traffic control, and remote sensing. Here a dynamic range compression two-beam-coupling joint transform correlator for detecting synthetic aperture radar targets is utilized. The joint input image consists of a prepower-law, enhanced scattering center of the input image and a linearly synthesized power-law-enhanced scattering center template. Enhancing the scattering center of both the synthetic template and the input image furnishes the conditions for achieving dynamic range compression correlation in two-beam coupling. Dynamic range compression (a) enhances the signal-to-noise ratio, (b) enhances the high frequencies relative to low frequencies, and (c) converts the noise to high frequency components. This improves the correlation-peak intensity to the mean of the surrounding noise significantly. Dynamic range compression correlation has already been demonstrated to outperform many optimal correlation filters in detecting signals in severe noise environments. The performance is evaluated via established metrics such as peak-to-correlation energy, Horner efficiency, and correlation-peak intensity. The results showed significant improvement as the power increased.

  4. Numerically correcting the joint misplacement of the sub-holograms in spatial synthetic aperture digital Fresnel holography.

    Science.gov (United States)

    Jiang, Hongzhen; Zhao, Jianlin; Di, Jianglei; Qin, Chuan

    2009-10-12

    We propose an effective reconstruction method for correcting the joint misplacement of the sub-holograms caused by the displacement error of CCD in spatial synthetic aperture digital Fresnel holography. For every two adjacent sub-holograms along the motion path of CCD, we reconstruct the corresponding holographic images under different joint distances between the sub-holograms and then find out the accurate joint distance by evaluating the quality of the corresponding synthetic reconstructed images. Then the accurate relative position relationships of the sub-holograms can be confirmed according to all of the identified joint distances, with which the accurate synthetic reconstructed image can be obtained by superposing the reconstruction results of the sub-holograms. The numerical reconstruction results are in agreement with the theoretical analysis. Compared with the traditional reconstruction method, this method could be used to not only correct the joint misplacement of the sub-holograms without the limitation of the actually overlapping circumstances of the adjacent sub-holograms, but also make the joint precision of the sub-holograms reach sub-pixel accuracy.

  5. The need for separate operational and engineering user interfaces for command and control of airborne synthetic aperture radar systems

    Science.gov (United States)

    Klein, Laura M.; McNamara, Laura A.

    2017-05-01

    In this paper, we address the needed components to create usable engineering and operational user interfaces (UIs) for airborne Synthetic Aperture Radar (SAR) systems. As airborne SAR technology gains wider acceptance in the remote sensing and Intelligence, Surveillance, and Reconnaissance (ISR) communities, the need for effective and appropriate UIs to command and control these sensors has also increased. However, despite the growing demand for SAR in operational environments, the technology still faces an adoption roadblock, in large part due to the lack of effective UIs. It is common to find operational interfaces that have barely grown beyond the disparate tools engineers and technologists developed to demonstrate an initial concept or system. While sensor usability and utility are common requirements to engineers and operators, their objectives for interacting with the sensor are different. As such, the amount and type of information presented ought to be tailored to the specific application.

  6. 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.

  7. Evidence for on-going inflation of the Socorro Magma Body, New Mexico, from interferometric synthetic aperture radar imaging

    Science.gov (United States)

    Fialko, Yuri; Simons, Mark

    Interferometric synthetic aperture radar (InSAR) imaging of the central Rio Grande rift (New Mexico, USA) during 1992-1999 reveals a crustal uplift of several centimeters that spatially coincides with the seismologically determined outline of the Socorro magma body, one of the largest currently active magma intrusions in the Earth’s continental crust. Modeling of interferograms shows that the observed deformation may be due to elastic opening of a sill-like intrusion at a rate of a few millimeters per year. Despite an apparent constancy of the geodetically determined uplift rate, thermodynamic arguments suggest that it is unlikely that the Socorro magma body has formed via steady state elastic inflation.

  8. 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.

  9. A technique for multitarget tracking in synthetic aperture radar spotlight imaging mode based on promoted PHD filtering approach

    Science.gov (United States)

    Daryasafar, N.; Sadeghzadeh, R. A.; Naser-Moghadasi, M.

    2017-02-01

    This paper investigates a new method based on promoted probability hypothesis density (PHD) filtering to simultaneously track several moving targets in data received by synthetic aperture radar (SAR) in spotlight imaging mode. Simultaneous tracking of several targets in the presence of high-density clutters in environment, as the particular capability of the PHD filter, has turned it into a robust approach in SAR to track moving targets. Given the PHD filter function as a sequence of prediction and update steps, it is more reasonable to apply the approach to the data received by the SAR in spotlight imaging mode; however, according to the specified system parameters, such method is not impossible to be implemented using the Stripmap imaging mode. According to simulation results, applying Range Cell Migration Compensation to the raw data received by SAR before tracking operation results in high-quality tracking of moving targets.

  10. Imaging method for downward-looking sparse linear array three-dimensional synthetic aperture radar based on reweighted atomic norm

    Science.gov (United States)

    Bao, Qian; Han, Kuoye; Lin, Yun; Zhang, Bingchen; Liu, Jianguo; Hong, Wen

    2016-01-01

    We propose an imaging algorithm for downward-looking sparse linear array three-dimensional synthetic aperture radar (DLSLA 3-D SAR) in the circumstance of cross-track sparse and nonuniform array configuration. Considering the off-grid effect and the resolution improvement, the algorithm combines pseudo-polar formatting algorithm, reweighed atomic norm minimization (RANM), and a parametric relaxation-based cyclic approach (RELAX) to improve the imaging performance with a reduced number of array antennas. RANM is employed in the cross-track imaging after pseudo-polar formatting the DLSLA 3-D SAR echo signal, then the reconstructed results are refined by RELAX. By taking advantage of the reweighted scheme, RANM can improve the resolution of the atomic norm minimization, and outperforms discretized compressive sensing schemes that suffer from off-grid effect. The simulated and real data experiments of DLSLA 3-D SAR verify the performance of the proposed algorithm.

  11. 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.

  12. On the Soil Roughness Parameterization Problem in Soil Moisture Retrieval of Bare Surfaces from Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Francesco Mattia

    2008-07-01

    Full Text Available 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. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale.

  13. Screening Mississippi River Levees Using Texture-Based and Polarimetric-Based Features from Synthetic Aperture Radar Data

    Directory of Open Access Journals (Sweden)

    Lalitha Dabbiru

    2017-03-01

    Full Text Available This article reviews the use of synthetic aperture radar remote sensing data for earthen levee mapping with an emphasis on finding the slump slides on the levees. Earthen levees built on the natural levees parallel to the river channel are designed to protect large areas of populated and cultivated land in the Unites States from flooding. One of the signs of potential impending levee failure is the appearance of slump slides. On-site inspection of levees is expensive and time-consuming; therefore, a need to develop efficient techniques based on remote sensing technologies is mandatory to prevent failures under flood loading. Analysis of multi-polarized radar data is one of the viable tools for detecting the problem areas on the levees. In this study, we develop methods to detect anomalies on the levee, such as slump slides and give levee managers new tools to prioritize their tasks. This paper presents results of applying the National Aeronautics and Space Administration (NASA Jet Propulsion Lab (JPL’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR quad-polarized L-band data to detect slump slides on earthen levees. The study area encompasses a portion of levees of the lower Mississippi River in the United States. In this paper, we investigate the performance of polarimetric and texture features for efficient levee classification. Texture features derived from the gray level co-occurrence (GLCM matrix and discrete wavelet transform were computed and analyzed for efficient levee classification. The pixel-based polarimetric decomposition features, such as entropy, anisotropy, and scattering angle were also computed and applied to the support vector machine classifier to characterize the radar imagery and compared the results with texture-based classification. Our experimental results showed that inclusion of textural features derived from the SAR data using the discrete wavelet transform (DWT features and GLCM features provided

  14. On the homogeneity of the wave field in coastal areas as determined from ERS-2 and RADARSAT synthetic aperture radar images of the ocean surface

    Directory of Open Access Journals (Sweden)

    F. J. Ocampo-Torres

    2001-07-01

    Full Text Available Spatial variations of the wave field in coastal waters were determined from images obtained by synthetic aperture radar (SAR on board the European satellites ERS-1 and 2. The capabilities of RADARSAT SAR to provide useful information for evaluating the wave field variation in nearshore waters are explored. Besides the different polarization between ERS and RADARSAT SARs, range to velocity ratios, signal to noise ratios and the acquisition swath are important issues to take into consideration in comparing the performance of the radar systems. In situ data from a coastal region in the north-west of Baja California are used to validate some of the remote observations and to provide relevant ground truth. Particular aspects of wave phenomena in finite depth waters such as refraction, diffraction and groupiness are considered. An appropriate method for analysing the radar images is applied to describe wave features as they originate from a non-homogeneous process. Wave field characteristics and their spatial variations as resolved by RADARSAT SAR are relevant variables for applications such as beach erosion and coastal management. Inclusion of specific modules to retrieve this type of information should be considered for operational software packages for the use and application of ocean surface data from SAR images. The differences of the two radar systems did not affect their capabilities to observe the wave field in coastal regions.

  15. Comparison of 3-D Synthetic Aperture Phased-Array Ultrasound Imaging and Parallel Beamforming

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2014-01-01

    This paper demonstrates that synthetic apertureimaging (SAI) can be used to achieve real-time 3-D ultra-sound phased-array imaging. It investigates whether SAI in-creases the image quality compared with the parallel beam-forming (PB) technique for real-time 3-D imaging. Data areobtained using bot...

  16. Modeling surface deformation observed with synthetic aperture radar interferometry at Campi Flegrei caldera

    NARCIS (Netherlands)

    Lundgren, P.; Usai, S.; Sansosti, E.; Lanari, R.; Tesauro, M.; Fornaro, G.; Berardino, P.

    2001-01-01

    Satellite radar interferometry of Campi Flegrei caldera, Italy, reveals a pattern of subsidence during the period 1993–1998. Interferograms spanning the first half of the observation period (1993–1995) have a lower amplitude and average rate of subsidence than those spanning either the second half

  17. Modeling surface deformation observed with synthetic aperture radar interferometry at Campi Flegrei caldera

    NARCIS (Netherlands)

    Lundgren, P.; Usai, S.; Sansosti, E.; Lanari, R.; Tesauro, M.; Fornaro, G.; Berardino, P.

    Satellite radar interferometry of Campi Flegrei caldera, Italy, reveals a pattern of subsidence during the period 1993–1998. Interferograms spanning the first half of the observation period (1993–1995) have a lower amplitude and average rate of subsidence than those spanning either the second half

  18. Study on Extremizing Adaptive Systems and Applications to Synthetic Aperture Radars.

    Science.gov (United States)

    1983-10-01

    EEEEEEEEE-hE T.V ~~ik 1 " 12.2 -A-m 1IL25 L 11111L MIROOP RSLTO TE3T CHR NATINALBUREU O STADARS- 163- EdO IIII’~f % %1 - %l---1 NAIOA 8UEU kSANAD 16 I...example problem would then * reflect the problem of placing a satellite into orbit without 4I7 " 75 S.. excessive residual motion. The same problem

  19. Inverse synthetic aperture radar processing using parametric time-frequency estimators Phase I

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J.V., LLNL

    1997-12-31

    This report summarizes the work performed for the Office of the Chief of Naval Research (ONR) during the period of 1 September 1997 through 31 December 1997. The primary objective of this research was aimed at developing an alternative time-frequency approach which is recursive-in-time to be applied to the Inverse Synthethic Aperture Radar (ISAR) imaging problem discussed subsequently. Our short term (Phase I) goals were to: 1. Develop an ISAR stepped-frequency waveform (SFWF) radar simulator based on a point scatterer vehicular target model incorporating both translational and rotational motion; 2. Develop a parametric, recursive-in-time approach to the ISAR target imaging problem; 3. Apply the standard time-frequency short-term Fourier transform (STFT) estimator, initially to a synthesized data set; and 4. Initiate the development of the recursive algorithm. We have achieved all of these goals during the Phase I of the project and plan to complete the overall development, application and comparison of the parametric approach to other time-frequency estimators (STFT, etc.) on our synthesized vehicular data sets during the next phase of funding. It should also be noted that we developed a batch minimum variance translational motion compensation (TMC) algorithm to estimate the radial components of target motion (see Section IV). This algorithm is easily extended to recursive solution and will probably become part of the overall recursive processing approach to solve the ISAR imaging problem. Our goals for the continued effort are to: 1. Develop and extend a complex, recursive-in-time, time- frequency parameter estimator based on the recursive prediction error method (RPEM) using the underlying Gauss- Newton algorithms. 2. Apply the complex RPEM algorithm to synthesized ISAR data using the above simulator. 3. Compare the performance of the proposed algorithm to standard time-frequency estimators applied to the same data sets.

  20. 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

    2011-03-01

    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

  1. Chosen results of field tests of synthetic aperture radar system installed on board UAV

    Science.gov (United States)

    Kaniewski, Piotr; Komorniczak, Wojciech; Lesnik, Czeslaw; Cyrek, Jacek; Serafin, Piotr; Labowski, Michal; Wajszczyk, Bronislaw

    2017-04-01

    The paper presents a synthetic information on a UAV-based radar terrain imaging system, its purpose, structure and working principle as well as terrain images obtained from flight experiments. A SAR technology demonstrator has been built as a result of a research project conducted by the Military University of Technology and WB Electronics S.A. under the name WATSAR. The developed system allows to obtain high resolution radar images, both in on-line and off-line modes, independently of the light conditions over the observed area. The software developed for the system allows to determine geographic coordinates of the imaged objects with high accuracy. Four LFM-CW radar sensors were built during the project: two for S band and two for Ku band, working with different signal bandwidths. Acquired signals were processed with the TDC algorithm, which allowed for a number of analyses in order to evaluate the performance of the system. The impact of the navigational corrections on a SAR image quality was assessed as well. The research methodology of the in-flight experiments of the system is presented in the paper. The projects results show that the developed system may be implemented as an aid to tactical C4ISR systems.

  2. Monitoring water levels by integrating optical and synthetic aperture radar water masks with lidar DEMs

    Science.gov (United States)

    Hopkinson, C.; Brisco, B.; Patterson, S.

    2014-12-01

    The ability to map and monitor wetland and lake open water extent and levels across the landscape allows improved estimates of watershed water balance, surface storage and flood inundation. The study presents open water classifications over the wetland dominated Sheppard Slough watershed east of Calgary in western Canada using parallel temporal imagery captured from the RapidEye and RadarSat satellites throughout 2013, a year of widespread and costly flood inundation in this region. The optical and SAR-based temporal image stacks were integrated with a high-resolution lidar DEM in order to delineate regions of inundation on the DEM surface. GIS techniques were developed to extract lidar-derived water surface elevations and track the spatio-temporal variation in pond and lake water level across the watershed. Water bodies were assigned unique identifiers so that levels could be tracked and linked to their associated watershed channel reach. The procedure of optical image classification through to merging of individual water bodies into watershed channel topology and extracting reach water levels has been automated within python scripts. The presentation will describe: i) the procedures used; ii) a comparison of the SAR and optical classification and water level extraction results; iii) a discussion of the spatio-temporal variations in water level across the Sheppard Slough watershed; and iv) a commentary on how the approach could be implemented for web-based operational monitoring and as simulation initialisation inputs for flood inundation model studies.

  3. 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.

  4. Synthetic aperture radar analysis of floating ice at Terra Nova Bay-an application to ice eddy parameter extraction

    Science.gov (United States)

    Moctezuma-Flores, Miguel; Parmiggiani, Flavio; Fragiacomo, Corrado; Guerrieri, Lorenzo

    2017-04-01

    In the framework of a study of ice formation in Antarctica, synthetic aperture radar (SAR) image acquisitions were planned over Terra Nova Bay (TNB). Thanks to the European Space Agency (ESA) Third Party Mission program, Cosmo-SkyMed and Radarsat-2 images over TNB were obtained for the period of February 20 to March 20, 2015; in addition, available Sentinel-1 images for the same period were retrieved from the ESA scientific data hub. The first inspection of the images revealed the presence of a prominent eddy, i.e., an ice vortex presumably caused by the wind blowing from the continent. The important parameters of an eddy are its area and lifetime. While the eddy lifetime was easily obtained from the image sequence, the area was measured using a specific processing scheme that consists of nonlinear filtering and Markov random field segmentation. The main goal of our study was to develop a segmentation scheme to detect and measure "objects" in SAR images. In addition, the connection between eddy area and wind field was investigated using parametric and nonparametric correlation functions; statistically significant correlation values were obtained in the analyzed period. After March 15, a powerful katabatic wind completely disrupted the surface eddy.

  5. 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.

  6. Polarimetric synthetic aperture radar application for tropical peatlands classification: a case study in Siak River Transect, Riau Province, Indonesia

    Science.gov (United States)

    Novresiandi, Dandy Aditya; Nagasawa, Ryota

    2017-01-01

    Mapping spatial distributions of tropical peatlands is important for properly estimating carbon emissions and for providing information that aids in the sustainable management of tropical peatlands, particularly in Indonesia. This study evaluated the performance of phased array type L-band synthetic aperture radar (SAR) (PALSAR) dual-polarization and fully polarimetric data for tropical peatlands classification. The study area was in Siak River Transect, Riau Province, Indonesia, a rapidly developing region, where the peatland has been intensively converted mostly into oil palm plantations over the last two decades. Thus, polarimetric features derived after polarimetric decompositions, backscatter coefficients measurements, and the radar vegetation index were evaluated to classify tropical peatlands using the decision tree classifier. Overall, polarimetric features generated by the combination of dual-polarization and fully polarimetric data yielded an overall accuracy (OA) of 69% and a kappa coefficient (K) of 0.57. The integration of an additional feature, "distance to river," to the algorithm increased the OA to 76% and K to 0.66. These results indicated that the methodology in this study might serve as an efficient tool in tropical peatlands classification, especially when involving the use of L-band SAR dual-polarization and fully polarimetric data.

  7. Lithology-controlled subsidence and seasonal aquifer response in the Bandung basin, Indonesia, observed by synthetic aperture radar interferometry

    Science.gov (United States)

    Khakim, Mokhamad Yusup Nur; Tsuji, Takeshi; Matsuoka, Toshifumi

    2014-10-01

    Land subsidence in the Bandung basin, West Java, Indonesia, is characterized based on differential interferometric synthetic aperture radar (DInSAR) and interferometric point target analysis (IPTA). We generated interferograms from 21 ascending SAR images over the period 1 January 2007 to 3 March 2011. The estimated subsidence history shows that subsidence continuously increased reaching a cumulative 45 cm during this period, and the linear subsidence rate reached ∼12 cm/yr. This significant subsidence occurred in the industrial and densely populated residential regions of the Bandung basin where large amounts of groundwater are consumed. However, in several areas the subsidence patterns do not correlate with the distribution of groundwater production wells and mapped aquifer degradation. We conclude that groundwater production controls subsidence, but lithology is a counteracting factor for subsidence in the Bandung basin. Moreover, seasonal trends of nonlinear surface deformations are highly related with the variation of rainfall. They indicate that there is elastic expansion (rebound) of aquifer system response to seasonal-natural recharge during rainy season.

  8. 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.

  9. Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field

    Energy Technology Data Exchange (ETDEWEB)

    Foxall, W; Vasco, D

    2003-02-07

    We used synthetic aperture radar interferograms to image ground subsidence that occurred over the Dixie Valley geothermal field during different time intervals between 1992 and 1997. Linear elastic inversion of the subsidence that occurred between April, 1996 and March, 1997 revealed that the dominant sources of deformation during this time period were large changes in fluid volumes at shallow depths within the valley fill above the reservoir. The distributions of subsidence and subsurface volume change support a model in which reduction in pressure and volume of hot water discharging into the valley fill from localized upflow along the Stillwater range frontal fault is caused by drawdown within the upflow zone resulting from geothermal production. Our results also suggest that an additional source of fluid volume reduction in the shallow valley fill might be similar drawdown within piedmont fault zones. Shallow groundwater flow in the vicinity of the field appears to be controlled on the NW by a mapped fault and to the SW by a lineament of as yet unknown origin.

  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. Inspection of copper canisters for spent nuclear fuel by means of ultrasound. Nonlinear acoustics, synthetic aperture imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lingvall, Fredrik; Ping Wu; Stepinski, Tadeusz [Uppsala Univ., (Sweden). Dept. of Materials Science

    2003-03-01

    This report contains results concerning inspection of copper canisters for spent nuclear fuel by means of ultrasound obtained at Signals and Systems, Uppsala University in year 2001/2002. The first chapter presents results of an investigation of a new method for synthetic aperture imaging. The new method presented here takes the form of a 2D filter based on minimum mean squared error (MMSE) criteria. The filter, which varies with the target position in two dimensions includes information about spatial impulse response (SIR) of the imaging system. Spatial resolution of the MMSE method is investigated and compared experimentally to that of the classical SAFT and phased array imaging. It is shown that the resolution of the MMSE algorithm, evaluated for imaging immersed copper specimen is superior to that observed for the two above-mentioned methods. Extended experimental and theoretical research concerning the potential of nonlinear waves and material harmonic imaging is presented in the second chapter. An experimental work is presented that was conducted using the RITEC RAM-5000 ultrasonic system capable of providing a high power tone-burst output. A new method for simulation of nonlinear acoustic waves that is a combination of the angular spectrum approach and the Burger's equation is also presented. This method was used for simulating nonlinear elastic waves radiated by the annular transducer that was used in the experiments.

  12. Photonics-based broadband radar for high-resolution and real-time inverse synthetic aperture imaging.

    Science.gov (United States)

    Zhang, Fangzheng; Guo, Qingshui; Wang, Ziqian; Zhou, Pei; Zhang, Guoqiang; Sun, Jun; Pan, Shilong

    2017-07-10

    A photonics-based radar with generation and de-chirp processing of broadband linear frequency modulated continuous-wave (LFMCW) signal in optical domain is proposed for high-resolution and real-time inverse synthetic aperture radar (ISAR) imaging. In the proposed system, a broadband LFMCW signal is generated by a photonic frequency quadrupler based on a single integrated electro-optical modulator, and the echoes reflected from the targets are de-chirped to a low frequency signal by a microwave photonic frequency mixer. The proposed radar can operate at a high frequency with a large bandwidth, and thus achieve an ultra-high range resolution for ISAR imaging. Thanks to the wideband photonic de-chirp technique, the radar receiver could apply low-speed analog-to-digital conversion and mature digital signal processing, which makes real-time ISAR imaging possible. A K-band photonics-based radar with an instantaneous bandwidth of 8 GHz (18-26 GHz) is established and its performance for ISAR imaging is experimentally investigated. Results show that a recorded two-dimensional imaging resolution of ~2 cm × ~2 cm is achieved with a sampling rate of 100 MSa/s in the receiver. Besides, fast ISAR imaging with 100 frames per second is verified. The proposed radar is an effective solution to overcome the limitations on operation bandwidth and processing speed of current radar imaging technologies, which may enable applications where high-resolution and real-time radar imaging is required.

  13. 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.

  14. Using temporarily coherent point interferometric synthetic aperture radar for land subsidence monitoring in a mining region of western China

    Science.gov (United States)

    Fan, Hongdong; Xu, Qiang; Hu, Zhongbo; Du, Sen

    2017-04-01

    Yuyang mine is located in the semiarid western region of China where, due to serious land subsidence caused by underground coal exploitation, the local ecological environment has become more fragile. An advanced interferometric synthetic aperture radar (InSAR) technique, temporarily coherent point InSAR, is applied to measure surface movements caused by different mining conditions. Fifteen high-resolution TerraSAR-X images acquired between October 2, 2012, and March 27, 2013, were processed to generate time-series data for ground deformation. The results show that the maximum accumulated values of subsidence and velocity were 86 mm and 162 mm/year, respectively; these measurements were taken above the fully mechanized longwall caving faces. Based on the dynamic land subsidence caused by the exploitation of one working face, the land subsidence range was deduced to have increased 38 m in the mining direction with 11 days' coal extraction. Although some mining faces were ceased in 2009, they could also have contributed to a small residual deformation of overlying strata. Surface subsidence of the backfill mining region was quite small, the maximum only 21 mm, so backfill exploitation is an effective method for reducing the land subsidence while coal is mined.

  15. Characterization of L-band synthetic aperture radar (SAR) backscatter from floating and grounded thermokarst lake ice in Arctic Alaska

    Science.gov (United States)

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

    2013-11-01

    Radar remote sensing is a well-established method to discriminate lakes retaining liquid-phase water beneath winter ice cover from those that do not. L-band (23.6 cm wavelength) airborne radar showed great promise in the 1970s, but spaceborne synthetic aperture radar (SAR) studies have focused on C-band (5.6 cm) SAR to classify lake ice with no further attention to L-band SAR for this purpose. Here, we examined calibrated L-band single- and quadrature-polarized SAR returns from floating and grounded lake ice in two regions of Alaska: the northern Seward Peninsula (NSP) where methane ebullition is common in lakes and the Arctic Coastal Plain (ACP) where ebullition is relatively rare. We found average backscatter intensities of -13 dB and -16 dB for late winter floating ice on the NSP and ACP, respectively, and -19 dB for grounded ice in both regions. Polarimetric analysis revealed that the mechanism of L-band SAR backscatter from floating ice is primarily roughness at the ice-water interface. L-band SAR showed less contrast between floating and grounded lake ice than C-band; however, since L-band is sensitive to ebullition bubbles trapped by lake ice (bubbles increase backscatter), this study helps elucidate potential confounding factors of grounded ice in methane studies using SAR.

  16. Identifying Successive Eruption of Guntur Volcanic Complex Using Magnetic Susceptibility and Polarimetric Synthetic Aperture Radar (PolSAR) Data

    Science.gov (United States)

    Saepuloh, Asep; Bakker, Erwin

    2017-06-01

    Identifying distribution and stratigraphic of volcanic products are important not only for mitigating volcanic hazards, but also to know the characteristics of the successive eruptions. Guntur volcanic complex located in Garut, West Java, Indonesia was selected as study area because of the last eruption took place in 1847 and the volcanic activity has been dormant since then, however its seismicity is still active. During the period of July to October 2009, the hypocentre distribution of volcano tectonic earthquakes is mostly located at western flank of the volcano, beneath Guntur - Gandapura craters at the depth of less than 5 km. This study is aimed to identify distribution and succession of volcanic products based on their magnetic properties and backscattering signal of Polarimetric Synthetic Aperture Radar (PolSAR) data. The polarimetric decomposition method was used to identify the distribution of the volcanic products based on their scattering characteristics. Then, the field measurement using SM-30 magnetic susceptibility meter was performed to confirm the units of volcanic products and interpret their successions. According to the polarimetric decomposition method, we could identify fifteen successive eruptions formed Guntur Volcano Complex and termed as Khuluk and Gumuk in Indonesian standard. The successions were produced Gumuk Windu, Gumuk Malang, Gumuk Pulus, Gumuk Putrri, Khuluk Meungpeuk, Gumuk Cakra, Gumuk Gandapura, Gumuk Putri, Gumuk Gajah, Gumuk Batususun, Khuluk Pasirlaku, Gumuk Agung, Gumuk Picung, Gumuk Pasirmalang, Gumuk Masigit, Khuluk Kabuyutan and Khuluk Guntur. The magnetic susceptibility confirmed that the variations of magnetic susceptibility of rocks at each gumuk agreed with their stratigraphy.

  17. Improved synthetic aperture focusing technique by Hilbert-Huang transform for imaging defects inside a concrete structure.

    Science.gov (United States)

    Tong, Jian-Hua; Chiu, Chin-Lung; Wang, Chung-Yue

    2010-11-01

    A useful nondestructive testing tool for civil engineering should immediately reveal defects inside concrete structures at the construction sites. To date, there are few effective methods to image defects inside concrete structures. In this paper, a new nondestructive testing method using elastic waves for imaging possible defects inside concrete is developed. This method integrates the point-source/point receiver scheme with the synthetic aperture focusing technique (SAFT) to increase functioning depth and enhance received signals. To improve image quality, received signals are processed by Hilbert-Huang transform (HHT) to get time-frequency curves for the SAFT process. Compared with conventional SAFT method processing with time-amplitude signals, this new method is capable of providing a better image of defects not only in the numerical simulation but also in the experimental result. The image can reveal the number of defects and their locations and front-end profiles. The results shown in this paper indicate that this new elastic-wave-based method exhibits high capability in imaging the defects of in situ concrete structures.

  18. Mapping of Ice Motion in Antarctica Using Synthetic-Aperture Radar Data

    Directory of Open Access Journals (Sweden)

    Bernd Scheuchl

    2012-09-01

    Full Text Available Ice velocity is a fundamental parameter in studying the dynamics of ice sheets. Until recently, no complete mapping of Antarctic ice motion had been available due to calibration uncertainties and lack of basic data. Here, we present a method for calibrating and mosaicking an ensemble of InSAR satellite measurements of ice motion from six sensors: the Japanese ALOS PALSAR, the European Envisat ASAR, ERS-1 and ERS-2, and the Canadian RADARSAT-1 and RADARSAT-2. Ice motion calibration is made difficult by the sparsity of in-situ reference points and the shear size of the study area. A sensor-dependent data stacking scheme is applied to reduce measurement uncertainties. The resulting ice velocity mosaic has errors in magnitude ranging from 1 m/yr in the interior regions to 17 m/yr in coastal sectors and errors in flow direction ranging from less than 0.5 in areas of fast flow to unconstrained direction in sectors of slow motion. It is important to understand how these mosaics are calibrated to understand the inner characteristics of the velocity products as well as to plan future InSAR acquisitions in the Antarctic. As an example, we show that in broad sectors devoid of ice-motion control, it is critical to operate ice motion mapping on a large scale to avoid pitfalls of calibration uncertainties that would make it difficult to obtain quality products and especially construct reliable time series of ice motion needed to detect temporal changes.

  19. 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

  20. A Spaceborne Synthetic Aperture Radar Partial Fixed-Point Imaging System Using a Field- Programmable Gate Array−Application-Specific Integrated Circuit Hybrid Heterogeneous Parallel Acceleration Technique

    Directory of Open Access Journals (Sweden)

    Chen Yang

    2017-06-01

    Full Text Available With the development of satellite load technology and very large scale integrated (VLSI circuit technology, onboard real-time synthetic aperture radar (SAR imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design is to achieve high real-time processing performance with severe size, weight, and power consumption constraints. In this paper, we analyse the computational burden of the commonly used chirp scaling (CS SAR imaging algorithm. To reduce the system hardware cost, we propose a partial fixed-point processing scheme. The fast Fourier transform (FFT, which is the most computation-sensitive operation in the CS algorithm, is processed with fixed-point, while other operations are processed with single precision floating-point. With the proposed fixed-point processing error propagation model, the fixed-point processing word length is determined. The fidelity and accuracy relative to conventional ground-based software processors is verified by evaluating both the point target imaging quality and the actual scene imaging quality. As a proof of concept, a field- programmable gate array−application-specific integrated circuit (FPGA-ASIC hybrid heterogeneous parallel accelerating architecture is designed and realized. The customized fixed-point FFT is implemented using the 130 nm complementary metal oxide semiconductor (CMOS technology as a co-processor of the Xilinx xc6vlx760t FPGA. A single processing board requires 12 s and consumes 21 W to focus a 50-km swath width, 5-m resolution stripmap SAR raw data with a granularity of 16,384 × 16,384.

  1. A Spaceborne Synthetic Aperture Radar Partial Fixed-Point Imaging System Using a Field- Programmable Gate Array-Application-Specific Integrated Circuit Hybrid Heterogeneous Parallel Acceleration Technique.

    Science.gov (United States)

    Yang, Chen; Li, Bingyi; Chen, Liang; Wei, Chunpeng; Xie, Yizhuang; Chen, He; Yu, Wenyue

    2017-06-24

    With the development of satellite load technology and very large scale integrated (VLSI) circuit technology, onboard real-time synthetic aperture radar (SAR) imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design is to achieve high real-time processing performance with severe size, weight, and power consumption constraints. In this paper, we analyse the computational burden of the commonly used chirp scaling (CS) SAR imaging algorithm. To reduce the system hardware cost, we propose a partial fixed-point processing scheme. The fast Fourier transform (FFT), which is the most computation-sensitive operation in the CS algorithm, is processed with fixed-point, while other operations are processed with single precision floating-point. With the proposed fixed-point processing error propagation model, the fixed-point processing word length is determined. The fidelity and accuracy relative to conventional ground-based software processors is verified by evaluating both the point target imaging quality and the actual scene imaging quality. As a proof of concept, a field- programmable gate array-application-specific integrated circuit (FPGA-ASIC) hybrid heterogeneous parallel accelerating architecture is designed and realized. The customized fixed-point FFT is implemented using the 130 nm complementary metal oxide semiconductor (CMOS) technology as a co-processor of the Xilinx xc6vlx760t FPGA. A single processing board requires 12 s and consumes 21 W to focus a 50-km swath width, 5-m resolution stripmap SAR raw data with a granularity of 16,384 × 16,384.

  2. Estimating the Above-Ground Biomass in Miombo Savanna Woodlands (Mozambique, East Africa Using L-Band Synthetic Aperture Radar Data

    Directory of Open Access Journals (Sweden)

    Maria J. Vasconcelos

    2013-03-01

    Full Text Available The quantification of forest above-ground biomass (AGB is important for such broader applications as decision making, forest management, carbon (C stock change assessment and scientific applications, such as C cycle modeling. However, there is a great uncertainty related to the estimation of forest AGB, especially in the tropics. The main goal of this study was to test a combination of field data and Advanced Land Observing Satellite (ALOS Phased Array L-band Synthetic Aperture Radar (PALSAR backscatter intensity data to reduce the uncertainty in the estimation of forest AGB in the Miombo savanna woodlands of Mozambique (East Africa. A machine learning algorithm, based on bagging stochastic gradient boosting (BagSGB, was used to model forest AGB as a function of ALOS PALSAR Fine Beam Dual (FBD backscatter intensity metrics. The application of this method resulted in a coefficient of correlation (R between observed and predicted (10-fold cross-validation forest AGB values of 0.95 and a root mean square error of 5.03 Mg·ha−1. However, as a consequence of using bootstrap samples in combination with a cross validation procedure, some bias may have been introduced, and the reported cross validation statistics could be overoptimistic. Therefore and as a consequence of the BagSGB model, a measure of prediction variability (coefficient of variation on a pixel-by-pixel basis was also produced, with values ranging from 10 to 119% (mean = 25% across the study area. It provides additional and complementary information regarding the spatial distribution of the error resulting from the application of the fitted model to new observations.

  3. Remote Sensing of Epibenthic Shellfish Using Synthetic Aperture Radar Satellite Imagery

    NARCIS (Netherlands)

    Nieuwhof, S.; Herman, P.M.J.; Dankers, N.; Troost, K.; van der Wal, D.

    2015-01-01

    On intertidal mudflats, reef-building shellfish, like the Pacific oyster and the blue mussel, provide a myriad of ecosystem services. Monitoring intertidal shellfish with high spatiotemporal resolution is important for fisheries, coastal management and ecosystem studies. Here, we explore the

  4. Remote sensing of epibenhtic shellfish using synthetic aperture radar satellite imagery

    NARCIS (Netherlands)

    Nieuwhof, S.; Herman, P.M.J.; Dankers, N.M.J.A.; Troost, K.; Wal, van der D.

    2015-01-01

    On intertidal mudflats, reef-building shellfish, like the Pacific oyster and the blue mussel, provide a myriad of ecosystem services. Monitoring intertidal shellfish with high spatiotemporal resolution is important for fisheries, coastal management and ecosystem studies. Here, we explore the

  5. Remote Sensing of Epibenthic Shellfish Using Synthetic Aperture Radar Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Sil Nieuwhof

    2015-03-01

    Full Text Available On intertidal mudflats, reef-building shellfish, like the Pacific oyster and the blue mussel, provide a myriad of ecosystem services. Monitoring intertidal shellfish with high spatiotemporal resolution is important for fisheries, coastal management and ecosystem studies. Here, we explore the potential of X- (TerraSAR-X and C-band (Radarsat-2 dual-polarized SAR data to map shellfish densities, species and coverage. We investigated two backscatter models (the integral equation model (IEM and Oh’s model for inversion possibilities. Surface roughness (vertical roughness RMSz and correlation length L was measured of bare sediments and shellfish beds, which was then linked to shellfish density, presence and species. Oysters, mussels and bare sediments differed in RMSz, but because the backscatter saturates at relatively low RMSz values, it was not possible to retrieve shellfish density or species composition from X- and C-band SAR. Using a classification based on univariate and multivariate logistic regression of the field and SAR image data, we constructed maps of shellfish presence (Kappa statistics for calibration 0.56–0.74 for dual-polarized SAR, which were compared with independent field surveys of the contours of the beds (Kappa statistics of agreement 0.29–0.53 when using dual-polarized SAR. We conclude that spaceborne SAR allows one to monitor the contours of shellfish-beds (thus, distinguishing shellfish substrates from bare sediment and dispersed single shellfish, but not densities and species. Although spaceborne SAR cannot replace ground surveys entirely, it could very well offer a significant improvement in efficiency.

  6. Ground motion measurement in the Lake Mead area, Nevada, by differential synthetic aperture radar interferometry time series analysis: Probing the lithosphere rheological structure

    OpenAIRE

    Cavalié, O; Doin, M.-P; Lasserre, C; Briole, P.

    2007-01-01

    International audience; [1] 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...

  7. Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

    Directory of Open Access Journals (Sweden)

    Laode M Golok Jaya

    2017-07-01

    Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

  8. Forest above ground biomass estimation and forest/non-forest classification for Odisha, India, using L-band Synthetic Aperture Radar (SAR) data

    Science.gov (United States)

    Suresh, M.; Kiran Chand, T. R.; Fararoda, R.; Jha, C. S.; Dadhwal, V. K.

    2014-11-01

    Tropical forests contribute to approximately 40 % of the total carbon found in terrestrial biomass. In this context, forest/non-forest classification and estimation of forest above ground biomass over tropical regions are very important and relevant in understanding the contribution of tropical forests in global biogeochemical cycles, especially in terms of carbon pools and fluxes. Information on the spatio-temporal biomass distribution acts as a key input to Reducing Emissions from Deforestation and forest Degradation Plus (REDD+) action plans. This necessitates precise and reliable methods to estimate forest biomass and to reduce uncertainties in existing biomass quantification scenarios. The use of backscatter information from a host of allweather capable Synthetic Aperture Radar (SAR) systems during the recent past has demonstrated the potential of SAR data in forest above ground biomass estimation and forest / nonforest classification. In the present study, Advanced Land Observing Satellite (ALOS) / Phased Array L-band Synthetic Aperture Radar (PALSAR) data along with field inventory data have been used in forest above ground biomass estimation and forest / non-forest classification over Odisha state, India. The ALOSPALSAR 50 m spatial resolution orthorectified and radiometrically corrected HH/HV dual polarization data (digital numbers) for the year 2010 were converted to backscattering coefficient images (Schimada et al., 2009). The tree level measurements collected during field inventory (2009-'10) on Girth at Breast Height (GBH at 1.3 m above ground) and height of all individual trees at plot (plot size 0.1 ha) level were converted to biomass density using species specific allometric equations and wood densities. The field inventory based biomass estimations were empirically integrated with ALOS-PALSAR backscatter coefficients to derive spatial forest above ground biomass estimates for the study area. Further, The Support Vector Machines (SVM) based Radial

  9. Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk

    Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts, lesions, and other processes. Almost any mass is first observed using B-mode imaging and later classified using e.g. color flow, strain, or attenuation imaging. It is therefore important that the B...... region of parenchyma. A successful approach to reduce the speckle artifacts is spatial compounding, where images are acquired from a number of directions and combined after envelope-detection. Today, spatial compounding is implemented in all highend ultrasound systems and available when using a low pitch...

  10. Pendugaan Potensi Cadangan Karbon Hutan di Atas Permukaan pada Ekosistem Mangrove Berbasis Synthetic Aperture Radar L-BAND

    Directory of Open Access Journals (Sweden)

    Yudi Fatwa Hudaya

    2016-10-01

    ABSTRACT The government policy to reduce the GHG (Green House Gas emision from forestry sector, the need for sufficient forest carbon stock measurement system which encompass a faster measurement and covering broader geographic area to estimate the potential of forest carbon stock is now growing, one of which is the use of synthetic aperture radar (SAR in radar remote sensing systems. The objectives of this study are to demonstrate the strong relationship between the L-band backscatter of ALOS PALSAR and the aboveground carbon stock in mangrove forest; and its sensitivity level. The information resulted from this study can be useful in reducing strategies of GHG (Green House Gases emision, due to the climate change mitigation efforts in Indonesia. The study site was located at the area of mangrove forest, in Kubu Raya regency, West Kalimantan. The estimation models for aboveground biomass carbon stock was obtained from a quantitative analysis using regression method; i.e. by correlating the values of ALOS PALSAR 50m Res. backscatters at HH and HV polarization with the actual biomass total amount resulted from field -based allometric plots measurements. The estimation models were subsequently use for forest carbon stocks quantification in mangroves, and its distribution geographically. Strong relationship was found with coefficient of determination (R2 62 % on HH polarization based on the equation model of Y=1647e0,358BS_HH  and , 98.6 % on HV polarization based on the equation model of Y = 6,828BS_HV2 + 279,4BS_HV + 2870; two models of carbon density classification maps i.e. model-1 (HH and model-2 (HV are also resulted from the two equation models. The quantity of AGB (aboveground biomass of  mangrove forest in Kubu Raya district found as 178.43 Mg/ ha, while the aboveground biomass carbon is 5,334,454.9 Mg (Mega grams or 5,3 Mt (Mega tons of carbon, and the capacity of carbon dioxide (CO2 sequestration is 19.451 Mt (megatons CO2 equivalent. The Sensitivity of L

  11. Monitoring of sinkholes and subsidence affecting the Jordanian coast of the Dead Sea through Synthetic Aperture Radar data and last generation Sentinel-1 data

    Science.gov (United States)

    Tessari, Giulia; Riccardi, Paolo; Lecci, Daniele; Pasquali, Paolo; Floris, Mario

    2017-04-01

    Since the mid-1980s the coast of the Dead Sea is affected by sinkholes occurring over and around the emerged mud and salt flats. Strong subsidence and landslides also affect some segments of the coast. Nowadays, several thousands of sinkholes attest that the degradation of the Dead Sea coast is worsening. Furthermore, soil deformations are interesting the main streets running along both the Israeli and Jordanian sides of the Dead Sea. These hazards are due to the dramatic dropping of the Dead Sea level, characterized by an increasing rate from about 60 cm/yr in the 1970s up to 1 m/yr in the 2000s, which provokes a lowering of the fresh-saline groundwater interface, replacing the hypersaline groundwater with fresh water and causing a consequent erosion of the subsurface salt layers. Subsidence, sinkholes, river erosion and landslides damage bridges, roads, dikes, houses, factories worsening this ongoing disaster. One of the most emblematic effects is the catastrophic collapse of a 12-km newly constructed dyke, located on the Lisan Peninsula (Jordan), occurred in 2000. Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques and Advanced stacking DInSAR techniques (A-DInSAR) were applied to investigate sinkholes and subsidence affecting the Jordanian coast of the Dead Sea. The use of SAR data already proof to be efficient on the risk management of the area, allowing to identify a vulnerable portion of an Israeli highway, averting a possible collapse. Deformation analysis has been focused on the Ghor Al Haditha area and Lisan peninsula, located in the South-Eastern part of the lake coast. The availability of a huge database of SAR data, since the beginning of the 90s, allowed to observe the evolution of the displacements which are damaging this area. Furthermore, last generation Sentinel-1 data, acquired by the ESA mission, were processed to obtain information about the recent evolution of the subsidence and sinkholes affecting the study area, from

  12. Characteristics and performance of L-band radar-based soil moisture retrievals using Soil Moisture Active Passive (SMAP) synthetic aperture radar observations

    Science.gov (United States)

    Kim, S.; Johnson, J. T.; Moghaddam, M.; Tsang, L.; Colliander, A.

    2016-12-01

    Surface soil moisture of the top 5-cm was estimated at 3-km spatial resolution using L-band dual-copolarized Soil Moisture Active Passive (SMAP) synthetic aperture radar (SAR) data that mapped the globe every three days from mid-April to early July, 2015. Radar observations of soil moisture offer the advantage of high spatial resolution, but have been challenging in the past due to the complicating factors of surface roughness and vegetation scattering. In this work, physically-based forward models of radar scattering for individual vegetation types are inverted using a time-series approach to retrieve soil moisture while correcting for the effects of roughness and dynamic vegetation. The predictions of the forward models used agree with SMAP measurements to within 0.5 dB unbiased-RMSE (root mean square error, ubRMSE) and -0.05 dB (bias). The forward models further allow the mechanisms of radar scattering to be examined to identify the sensitivity of radar scattering to soil moisture. Global patterns of the soil moistures retrieved by the algorithm generally match well with those from other satellite sensors. However biases exist in dry regions, and discrepancies are found in thick vegetation areas. The retrievals are compared with in situ measurements of soil moisture in locations characterized as cropland, grassland, and woody vegetation. Terrain slopes, subpixel heterogeneity, tillage practices, and vegetation growth influence the retrievals, but are largely corrected by the retrieval processes. Soil moisture retrievals agree with the in-situ measurements at 0.052 m3/m3 ubRMSE, -0.015 m3/m3 bias, and a correlation of 0.50. These encouraging retrieval results demonstrate the feasibility of a physically-based time-series retrieval with L-band SAR data for characterizing soil moisture over diverse conditions of soil moisture, surface roughness, and vegetation types. The findings are important for future L-band radar missions with frequent revisits that permit time

  13. Learning Change from Synthetic Aperture Radar Images: Performance Evaluation of a Support Vector Machine to Detect Earthquake and Tsunami-Induced Changes

    Directory of Open Access Journals (Sweden)

    Marc Wieland

    2016-09-01

    Full Text Available This study evaluates the performance of a Support Vector Machine (SVM classifier to learn and detect changes in single- and multi-temporal X- and L-band Synthetic Aperture Radar (SAR images under varying conditions. The purpose is to provide guidance on how to train a powerful learning machine for change detection in SAR images and to contribute to a better understanding of potentials and limitations of supervised change detection approaches. This becomes particularly important on the background of a rapidly growing demand for SAR change detection to support rapid situation awareness in case of natural disasters. The application environment of this study thus focuses on detecting changes caused by the 2011 Tohoku earthquake and tsunami disaster, where single polarized TerraSAR-X and ALOS PALSAR intensity images are used as input. An unprecedented reference dataset of more than 18,000 buildings that have been visually inspected by local authorities for damages after the disaster forms a solid statistical population for the performance experiments. Several critical choices commonly made during the training stage of a learning machine are being assessed for their influence on the change detection performance, including sampling approach, location and number of training samples, classification scheme, change feature space and the acquisition dates of the satellite images. Furthermore, the proposed machine learning approach is compared with the widely used change image thresholding. The study concludes that a well-trained and tuned SVM can provide highly accurate change detections that outperform change image thresholding. While good performance is achieved in the binary change detection case, a distinction between multiple change classes in terms of damage grades leads to poor performance in the tested experimental setting. The major drawback of a machine learning approach is related to the high costs of training. The outcomes of this study, however

  14. Recent advances in airborne terrestrial remote sensing with the NASA airborne visible/infrared imaging spectrometer (AVIRIS), airborne synthetic aperture radar (SAR), and thermal infrared multispectral scanner (TIMS)

    Science.gov (United States)

    Vane, Gregg; Evans, Diane L.; Kahle, Anne B.

    1989-01-01

    Significant progress in terrestrial remote sensing from the air has been made with three NASA-developed sensors that collectively cover the solar-reflected, thermal infrared, and microwave regions of the electromagnetic spectrum. These sensors are the airborne visible/infrared imaging spectrometer (AVIRIS), the thermal infrared mapping spectrometer (TIMS) and the airborne synthetic aperture radar (SAR), respectively. AVIRIS and SAR underwent extensive in-flight engineering testing in 1987 and 1988 and are scheduled to become operational in 1989. TIMS has been in operation for several years. These sensors are described.

  15. Comparing range data across the slow-time dimension to correct motion measurement errors beyond the range resolution of a synthetic aperture radar

    Science.gov (United States)

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2010-08-17

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  16. Exploratory Data Analysis of Synthetic Aperture Radar (SAR Measurements to Distinguish the Sea Surface Expressions of Naturally-Occurring Oil Seeps from Human-Related Oil Spills in Campeche Bay (Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Gustavo de Araújo Carvalho

    2017-12-01

    Full Text Available An Exploratory Data Analysis (EDA aims to use Synthetic Aperture Radar (SAR measurements for discriminating between two oil slick types observed on the sea surface: naturally-occurring oil seeps versus human-related oil spills—the use of satellite sensors for this task is poorly documented in scientific literature. A long-term RADARSAT dataset (2008–2012 is exploited to investigate oil slicks in Campeche Bay (Gulf of Mexico. Simple Classification Algorithms to distinguish the oil slick type are designed based on standard multivariate data analysis techniques. Various attributes of geometry, shape, and dimension that describe the oil slick Size Information are combined with SAR-derived backscatter coefficients—sigma-(σo, beta-(βo, and gamma-(γo naught. The combination of several of these characteristics is capable of distinguishing the oil slick type with ~70% of overall accuracy, however, the sole and simple use of two specific oil slick’s Size Information (i.e., area and perimeter is equally capable of distinguishing seeps from spills. The data mining exercise of our EDA promotes a novel idea bridging petroleum pollution and remote sensing research, thus paving the way to further investigate the satellite synoptic view to express geophysical differences between seeped and spilled oil observed on the sea surface for systematic use.

  17. 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

  18. Analysis of polarimetric synthetic aperture radar and passive visible light polarimetric imaging data fusion for remote sensing applications

    Science.gov (United States)

    Maitra, Sanjit

    The recent launch of spaceborne (TerraSAR-X, RADARSAT-2, ALOS-PALSAR, RISAT) and airborne (SIRC, AIRSAR, UAVSAR, PISAR) polarimetric radar sensors, with capability of imaging through day and night in almost all weather conditions, has made polarimetric synthetic aperture radar (PolSAR) image interpretation and analysis an active area of research. PolSAR image classification is sensitive to object orientation and scattering properties. In recent years, significant work has been done in many areas including agriculture, forestry, oceanography, geology, terrain analysis. Visible light passive polarimetric imaging has also emerged as a powerful tool in remote sensing for enhanced information extraction. The intensity image provides information on materials in the scene while polarization measurements capture surface features, roughness, and shading, often uncorrelated with the intensity image. Advantages of visible light polarimetric imaging include high dynamic range of polarimetric signatures and being comparatively straightforward to build and calibrate. This research is about characterization and analysis of the basic scattering mechanisms for information fusion between PolSAR and passive visible light polarimetric imaging. Relationships between these two modes of imaging are established using laboratory measurements and image simulations using the Digital Image and Remote Sensing Image Generation (DIRSIG) tool. A novel low cost laboratory based S-band (2.4GHz) PolSAR instrument is developed that is capable of capturing 4 channel fully polarimetric SAR image data. Simple radar targets are formed and system calibration is performed in terms of radar cross-section. Experimental measurements are done using combination of the PolSAR instrument with visible light polarimetric imager for scenes capturing basic scattering mechanisms for phenomenology studies. The three major scattering mechanisms studied in this research include single, double and multiple bounce. Single

  19. 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

  20. Satellite Remote Sensing in Offshore Wind Energy

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Astrup, Poul

    2013-01-01

    Satellite remote sensing of ocean surface winds are presented with focus on wind energy applications. The history on operational and research-based satellite ocean wind mapping is briefly described for passive microwave, scatterometer and synthetic aperture radar (SAR). Currently 6 GW installed...

  1. Target Area Extension in Synthetic Aperture Array Signal Processing for High-Frame-Rate Estimate of Two-Dimensional Motion Vector In vivo

    Science.gov (United States)

    Yagi, Shin-ichi; Yokoyama, Ryouta; Tamura, Kiyoshi; Sato, Masakazu

    2011-07-01

    A strategic synthetic aperture radar (SAR) along a flight path has been developed including a potential extensibility in a wide-range target area and an excellent spatial resolution by utilizing two-way range stacking, matched filtering, and chirp signal transmission. For the simultaneous ultrahigh-frame-rate ultrasonic imaging of microdynamics in a living tissue, a one-way synthetic aperture array processing of a real-time-received two-dimensional (2D) echo signal followed by a successive transmission is indispensable, in which the range stacking in SAR should be modified toward the pulsed ultrasonic irradiation generated by the array transducer. Therefore, the modification of the range stacking was proposed for pulsed radiation from a flexible point ultrasonic source. Firstly, a one-way receiving range stacking algorithm was described in a spatiotemporal frequency domain, and it was consequently extended to account for the forward-range- and cross-range-dependent time delay of the 2D echo signal in each range bin for the reconstruction of the target area. The overall system performance for the linear array transducer having 256 elements with a 3.0 MHz center frequency and a 0.25 mm pitch was verified for the reconstructed images in a numerical simulation and a hardware experiment.

  2. Study on spatial variation of land subsidence over Minagish-Umm Gudair oil fields of Kuwait using synthetic aperture radar interferometry technique

    Science.gov (United States)

    Rao, Kota S.; Al Jassar, Hala K.; Kodiyan, Nevil J.; Daniel, Viju P.

    2016-01-01

    Land subsidence can be a major problem where there are large-scale underground activities such as oil extraction. This paper addresses the spatial variability of land subsidence over Minagish and Umm Gudair oil fields of Kuwait. Synthetic aperture radar interferometry (InSAR) with multiple reference scenes using a persistent scatterer InSAR toolchain was employed in this study. Twenty-nine scenes of advanced synthetic aperture radar data (for the period January 2005 to August 2009) were used to make 20 pairs of interferograms (with high coherence and low noise) of stable point-like reflectors. The output of this study is the land subsidence maps of Minagish and Umm Gudair oil fields with a spatial resolution of 40 m. The results indicate that there is land subsidence of 29.9 mm/year in the southern part of the oil field (Umm Gudair). This is the first detailed assessment of land subsidence in the Minagish-Umm Gudair oil fields; therefore, no ground-truth data are available to compare the subsidence results. The results were consistent, indicating their validity.

  3. Methods of satellite oceanography

    Science.gov (United States)

    Stewart, R. H.

    1985-01-01

    The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

  4. Hunt for forgotten warplanes: a unique application for the Goddard Space Flight Center Search and Rescue Synthetic Aperture Radar (SAR2) program

    Science.gov (United States)

    Yagen, Gerald; Jackson, Christopher R.

    1998-09-01

    The principal purpose of the Beaconless Search and Rescue program at Goddard Space Flight Center (GSFC) is to utilize synthetic aperture radar (SAR) for the efficient and rapid location of recent small aircraft crashes. An additional side benefit might prove to be the detection and discovery of long lost or forgotten historic aircraft that have now become of immense value for museum display or among wealthy collectors. As the GSFC SAR2 program matures and its achievements in SAR target detection become more widely available, they will be of use to amateur and professional airplane hunters. We recommend that such ancillary benefits be kept in mind during the continued development and testing of such equipment, which would be of benefit to all future generations concerning the history of aviation. We welcome and encourage all participants to notify organizations such as ours of the discovery of any historic aircraft wreckage or intact abandoned old aircraft throughout the world.

  5. Small-scale loess landslide monitoring with small baseline subsets interferometric synthetic aperture radar technique-case study of Xingyuan landslide, Shaanxi, China

    Science.gov (United States)

    Zhao, Chaoying; Zhang, Qin; He, Yang; Peng, Jianbing; Yang, Chengsheng; Kang, Ya

    2016-04-01

    Small baseline subsets interferometric synthetic aperture radar technique is analyzed to detect and monitor the loess landslide in the southern bank of the Jinghe River, Shaanxi province, China. Aiming to achieve the accurate preslide time-series deformation results over small spatial scale and abrupt temporal deformation loess landslide, digital elevation model error, coherence threshold for phase unwrapping, and quality of unwrapping interferograms must be carefully checked in advance. In this experience, land subsidence accompanying a landslide with the distance sound precursor for small-scale loess landslide detection. Moreover, the longer and continuous land subsidence has been monitored while deformation starting point for the landslide is successfully inverted, which is key to monitoring the similar loess landslide. In addition, the accelerated landslide deformation from one to two months before the landslide can provide a critical clue to early warning of this kind of landslide.

  6. Microwave and Millimeter Wave Imaging of the Space Shuttle External Fuel Tank Spray on Foam Insulation (SOFI) using Synthetic Aperture Focusing Techniques (SAFT}

    Science.gov (United States)

    Case, J. T.; Robbins, J.; Kharkivskiy, S.; Hepburn, F.; Zoughi, R.

    2005-01-01

    The Space Shuttle Columbia s catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking the left wing of the orbiter causing significant damage to some of the reinforced carbodcarbon leading edge wing panels. Microwave and millimeter wave nondestructive evaluation methods have shown great potential for inspecting SOFI for the purpose of detecting anomalies such as small air voids that may cause separation of the SOFI from the external tank during a launch. These methods are capable of producing relatively high-resolution images of the interior of SOFI particularly when advanced imaging algorithms are incorporated into the overall system. To this end, synthetic aperture focusing techniques (SAFT) are being developed. This paper presents some of the preliminary results of this investigation using SAFT-based methods and microwave holography at relatively low frequencies illustrating their potential capabilities for operation at millimeter wave frequencies.

  7. Microwave and Millimeter Wave Imaging of the Space Shuttle External Fuel Tank Spray on Foam Insulation (SOFI) Using Synthetic Aperture Focusing Techniques (SAFT)

    Science.gov (United States)

    Case, J. T.; Robbins, J.; Kharkovsky, S.; Hepburn, F.; Zoughi, R.

    2006-03-01

    The Space Shuttle Columbia's catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking the left wing of the orbiter causing significant damage to some of the reinforced carbon/carbon leading edge wing panels. Microwave and millimeter wave nondestructive evaluation methods have shown great potential for inspecting SOFI for the purpose of detecting anomalies such as small air voids that may cause separation of the SOFI from the external tank during a launch. These methods are capable of producing relatively high-resolution images of the interior of SOFI particularly when advanced imaging algorithms are incorporated into the overall system. To this end, synthetic aperture focusing techniques (SAFT) are being developed. This paper presents some of the preliminary results of this investigation using SAFT-based methods and microwave holography at relatively low frequencies illustrating their potential capabilities for operation at millimeter wave frequencies.

  8. A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: design/operation/preliminary results.

    Science.gov (United States)

    Kennedy, J L; Marston, T M; Lee, K; Lopes, J L; Lim, R

    2014-01-01

    A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and

  9. 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.

  10. 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.

  11. 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.

  12. Principles and evaluation of an automatic target recognition system for synthetic aperture radar imagery based on the use of functional templates

    Science.gov (United States)

    Verly, Jacques G.; Delanoy, Richard L.; Lazott, Carol H.

    1993-10-01

    We describe an end-to-end Automatic Target Recognition (ATR) system for recognizing targets in Synthetic Aperture Radar (SAR) imagery. The system heavily relies on the use of functional template correlation, a technique recently developed by the authors for applying machine intelligence directly at the pixel level through the use of functional templates (FTs). Targets are detected using a CFAR-like, circularly-symmetric FT. They are recognized with azimuth-dependent FTs that deal with the fact that the appearance of an object in SAR imagery changes significantly with the direction of radar illumination relative to the object. FTs were specifically designed for ISAR data at 19 deg depression angle. Excellent recognition results were obtained when these FTs were blindly applied to over 20,000 ISAR images covering depression angles from 18 to 32 deg. When the same FTs were applied to 255 airborne stripmap SAR images at 22 deg, good recognition results were obtained with no false alarms. Although the paper deals primarily with fully polarimetric data, the ideas presented readily apply to single- or dual-polarization SARs.

  13. Inspection of copper canisters for spent nuclear fuel by means of ultrasound. Synthetic aperture imaging, evaluation of ultrasonic attenuation in copper

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Tadeusz (ed.); Lingvall, Fredrik; Wennerstroem, Erik; Ping Wu [Uppsala Univ. (Sweden). Department of Engineering Sciences

    2006-01-15

    This report contains the research results concerning advanced ultrasound for the inspection of copper canisters for spent nuclear fuel obtained at Signals and Systems, Uppsala University in years 2004/2005. After a short introduction a new super-resolution synthetic aperture imaging (SRSAI) technique is proposed. The proposed SRSAI is characterized by an excellent lateral resolution and much higher signal to noise ratio compared with ESAFT which was proposed in our previous reports. The ESAFT is based on the assumption that probability density of the imaged targets (so called prior) is Gaussian, which is the simplest case for the analysis. The increased performance of SRSAI is due to more realistic assumption concerning probability density function of targets in the region of interest. It is shown, both using simulations and in an experiment that if the target reflectivity is assumed to be positive a substantial increase of resolution and signal to noise ratio in the reconstructed image can be obtained. In the second chapter the result of the evaluation of ultrasonic attenuation in copper blocks with different grain size is presented. A short presentation of basic theory of the buffer-rod and the immersion methods is given in the beginning (the detailed derivation is provided in the appendix). Then the measurement setup and copper specimens are specified and the results of measurements made on copper specimens are presented. Correlation between the attenuation and grain size for the inspected specimens is discussed.

  14. High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR).

    Science.gov (United States)

    Wang, Ruijia; Chen, Jie; Wang, Xing; Sun, Bing

    2017-01-09

    Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method.

  15. Synthetic Aperture Radar (SAR)-based paddy rice monitoring system: Development and application in key rice producing areas in Tropical Asia

    Science.gov (United States)

    Setiyono, T. D.; Holecz, F.; Khan, N. I.; Barbieri, M.; Quicho, E.; Collivignarelli, F.; Maunahan, A.; Gatti, L.; Romuga, G. C.

    2017-01-01

    Reliable and regular rice information is essential part of many countries’ national accounting process but the existing system may not be sufficient to meet the information demand in the context of food security and policy. Synthetic Aperture Radar (SAR) imagery is highly suitable for detecting lowland paddy rice, especially in tropical region where pervasive cloud cover in the rainy seasons limits the use of optical imagery. This study uses multi-temporal X-band and C-band SAR imagery, automated image processing, rule-based classification and field observations to classify rice in multiple locations across Tropical Asia and assimilate the information into ORYZA Crop Growth Simulation model (CGSM) to generate high resolution yield maps. The resulting cultivated rice area maps had classification accuracies above 85% and yield estimates were within 81-93% agreement against district level reported yields. The study sites capture much of the diversity in water management, crop establishment and rice maturity durations and the study demonstrates the feasibility of rice detection, yield monitoring, and damage assessment in case of climate disaster at national and supra-national scales using multi-temporal SAR imagery combined with CGSM and automated methods.

  16. Detecting and Measuring Land Subsidence in Houston-Galveston, Texas using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System Data, 2012-2016

    Science.gov (United States)

    Reed, A.; Baker, S.

    2016-12-01

    Several cities in the Houston-Galveston (HG) region in Texas have subsided up to 13 feet over several decades due to natural and anthropogenic processes [Yu et al. 2014]. Land subsidence, a gradual sinking of the Earth's surface, is an often human-induced hazard and a major environmental problem expedited by activities such as mining, oil and gas extraction, urbanization and excessive groundwater pumping. We are able to detect and measure subsidence in HG using interferometric synthetic aperture radar (InSAR) and global positioning systems (GPS). Qu et al. [2015] used ERS, Envisat, and ALOS-1 to characterize subsidence in HG from 1995 to 2011, but a five-year gap in InSAR measurements exists due to a lack of freely available SAR data. We build upon the previous study by comparing subsidence patterns detected by Sentinel-1 data starting in July 2015. We used GMT5SAR to generate a stack of interferograms with perpendicular baselines less than 100 meters and temporal baselines less than 100 days to minimize temporal and spatial decorrelation. We applied the short baseline subset (SBAS) time series processing using GIAnT and compared our results with GPS measurements. The implications of this work will strengthen land subsidence monitoring systems in HG and broadly aid in the development of effective water resource management policies and strategies.

  17. Quantitative Estimation of Above Ground Crop Biomass using Ground-based, Airborne and Spaceborne Low Frequency Polarimetric Synthetic Aperture Radar

    Science.gov (United States)

    Koyama, C.; Watanabe, M.; Shimada, M.

    2016-12-01

    Estimation of crop biomass is one of the important challenges in environmental remote sensing related to agricultural as well as hydrological and meteorological applications. Usually passive optical data (photographs, spectral data) operating in the visible and near-infrared bands is used for such purposes. The virtue of optical remote sensing for yield estimation, however, is rather limited as the visible light can only provide information about the chemical characteristics of the canopy surface. Low frequency microwave signals with wavelength longer 20 cm have the potential to penetrate through the canopy and provide information about the whole vertical structure of vegetation from the top of the canopy down to the very soil surface. This phenomenon has been well known and exploited to detect targets under vegetation in the military radar application known as FOPEN (foliage penetration). With the availability of polarimetric interferometric SAR data the use PolInSAR techniques to retrieve vertical vegetation structures has become an attractive tool. However, PolInSAR is still highly experimental and suitable data is not yet widely available. In this study we focus on the use of operational dual-polarization L-band (1.27 GHz) SAR which is since the launch of Japan's Advanced Land Observing Satellite (ALOS, 2006-2011) available worldwide. Since 2014 ALOS-2 continues to deliver such kind of partial polarimetric data for the entire land surface. In addition to these spaceborne data sets we use airborne L-band SAR data acquired by the Japanese Pi-SAR-L2 as well as ultra-wideband (UWB) ground based SAR data operating in the frequency range from 1-4 GHz. By exploiting the complex dual-polarization [C2] Covariance matrix information, the scattering contributions from the canopy can be well separated from the ground reflections allowing for the establishment of semi-empirical relationships between measured radar reflectivity and the amount of fresh-weight above

  18. NORSEWInD satellite wind climatology

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Mouche, Alexis

    is to provide new offshore wind climatology map for the entire area of interest based on satellite remote sensing. This has been based on Synthetic Aperture Radar (SAR) from Envisat ASAR using 9000 scenes re-processed with ECMWF wind direction and CMOD-IFR. The number of overlapping samples range from 450...

  19. Discontinuous Non-Rigid Motion Analysis of Sea Ice using C-Band Synthetic Aperture Radar Satellite Imagery

    Science.gov (United States)

    2004-06-27

    with the ISW vectors. Scatter plots show the magnitude and phase vari- ation between our estimates and the ISW vectors for the spatially collocated ...and B̧ering Şeas. In International Glaciology Sym- posium, Fairbanks, Alaska, 2000. [35] R. E. Moritz and H. L. Stern. Relationships between

  20. Discontinuous Non-Rigid Motion Analysis of Sea Ice using C-Band Synthetic Aperture Radar Satellite Imagery

    National Research Council Canada - National Science Library

    Thomas, Mani; Geiger, Cathleen; Kambhamettu, Chandra

    2004-01-01

    ...) are still in the developmental stages. For interior Arctic and Antarctic pack ice, the continuum assumption begins to fail below the 5 km scale with evidence of discontinuities already revealed in models and remote sensing products...

  1. Advanced Communications Technology Satellite (ACTS) Fade Compensation Protocol Impact on Very Small-Aperture Terminal Bit Error Rate Performance

    Science.gov (United States)

    Cox, Christina B.; Coney, Thom A.

    1999-01-01

    The Advanced Communications Technology Satellite (ACTS) communications system operates at Ka band. ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of an analysis characterizing the improvement in VSAT performance provided by this protocol. The metric for performance is VSAT bit error rate (BER) availability. The acceptable availability defined by communication system design specifications is 99.5% for a BER of 5E-7 or better. VSAT BER availabilities with and without rain fade compensation are presented. A comparison shows the improvement in BER availability realized with rain fade compensation. Results are presented for an eight-month period and for 24 months spread over a three-year period. The two time periods represent two different configurations of the fade compensation protocol. Index Terms-Adaptive coding, attenuation, propagation, rain, satellite communication, satellites.

  2. Dark-spot segmentation for oil spill detection based on multifeature fusion classification in single-pol synthetic aperture radar imagery

    Science.gov (United States)

    Lang, Haitao; Zhang, Xingyao; Xi, Yuyang; Zhang, Xi; Li, Wei

    2017-01-01

    In recent years, oil spill surveillance with space-borne synthetic aperture radar (SAR) has received unprecedented attention and has been gradually developed into a common technique for maritime environment protection. A typical SAR-based oil spill detection process consists of three steps: (1) dark-spot segmentation, (2) feature extraction, and (3) oil spill and look-alike discrimination. As a preliminary task in the oil spill detection process chain, dark-spot segmentation is a critical and fundamental step prior to feature extraction and classification, since its output has a direct impact on the two subsequent stages. The balance between the detection probability and false alarm probability has a vital impact on the performance of the entire detection system. Unfortunately, this problem has not drawn as much attention as the other two stages. A specific effort has been placed on dark-spot segmentation in single-pol SAR imagery. A combination of fine designed features, including gray features, geometric features, and textural features, is proposed to characterize the oil spill and seawater for improving the performance of dark-spot segmentation. In the proposed process chain, a histogram stretching transform is incorporated before the gray feature extraction to enhance the contrast between possible oil spills and water. A simple but effective multiple-level thresholding algorithm is developed to conduct a binary classification before the geometric feature extraction to obtain more accurate area features. A local binary pattern code is computed and assigned as the textural feature for a pixel to characterize the physical difference between oil spills and water. The experimental result confirms that the proposed fine designed feature combination outperforms existing approaches in both aspects of overall segmentation accuracy and the capability to balance detection probability and false alarm probability. It is a promising alternative that can be incorporated into

  3. L-band Synthetic Aperture Radar imagery performs better than optical datasets at retrieving woody fractional cover in deciduous, dry savannahs

    Science.gov (United States)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Wessels, Konrad; Asner, Gregory P.

    2016-10-01

    Woody canopy cover (CC) is the simplest two dimensional metric for assessing the presence of the woody component in savannahs, but detailed validated maps are not currently available in southern African savannahs. A number of international EO programs (including in savannah landscapes) advocate and use optical LandSAT imagery for regional to country-wide mapping of woody canopy cover. However, previous research has shown that L-band Synthetic Aperture Radar (SAR) provides good performance at retrieving woody canopy cover in southern African savannahs. This study's objective was to evaluate, compare and use in combination L-band ALOS PALSAR and LandSAT-5 TM, in a Random Forest environment, to assess the benefits of using LandSAT compared to ALOS PALSAR. Additional objectives saw the testing of LandSAT-5 image seasonality, spectral vegetation indices and image textures for improved CC modelling. Results showed that LandSAT-5 imagery acquired in the summer and autumn seasons yielded the highest single season modelling accuracies (R2 between 0.47 and 0.65), depending on the year but the combination of multi-seasonal images yielded higher accuracies (R2 between 0.57 and 0.72). The derivation of spectral vegetation indices and image textures and their combinations with optical reflectance bands provided minimal improvement with no optical-only result exceeding the winter SAR L-band backscatter alone results (R2 of ∼0.8). The integration of seasonally appropriate LandSAT-5 image reflectance and L-band HH and HV backscatter data does provide a significant improvement for CC modelling at the higher end of the model performance (R2 between 0.83 and 0.88), but we conclude that L-band only based CC modelling be recommended for South African regions.

  4. Deepwater Horizon MC252 response data from the Environmental Resource Management Application (ERMA) containing Texture Classifying Neural Network Algorithm (TCNNA) from Synthetic Aperture Radar (SAR) nearshore potential oiling footprints collected from 2010-04-29 to 2010-08-11 in the Northern Gulf of Mexico (NCEI Accession 0163819)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival information package (AIP) contains Environmental Response Management Application (ERMA) GIS layers of outputs from Synthetic Aperture Radar (SAR)...

  5. Directional synthetic aperture flow imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav

    2004-01-01

    elements in each emission. A 20 us chirp was used during emission. The RF data were subsequently beamformed off-line and stationary echo canceling was performed. The 60 degrees flow with a peak velocity of 0.15 m/s was determined using 16 groups of 8 emissions and the relative standard deviation was 0.......36% (0.65 mm/s). Using the same set-up for the purely transverse flow gave a std. of 1.2% (2.1 mm/s). Variation of the different parameters has been done to reveal the sensitivity to number of lines, angle deviations, length of correlation interval, and sampling interval. An in-vivo image of the carotid...

  6. Sequential Beamforming Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2013-01-01

    compared to conventional ultrasound imaging. SASB is a two-stage procedure using two separate beamformers. The initial step is to construct and store a set of B-mode image lines using a single focal point in both transmit and receive. The focal points are considered virtual sources and virtual receivers...... making up a virtual array. The second stage applies the focused image lines from the first stage as input data, and take advantage of the virtual array in the delay and sum beamforming. The size of the virtual array is dynamically expanded and the image is dynamically focused in both transmit and receive...

  7. Synthetic

    Directory of Open Access Journals (Sweden)

    Anna Maria Manferdini

    2010-06-01

    Full Text Available Traditionally materials have been associated with a series of physical properties that can be used as inputs to production and manufacturing. Recently we witnessed an interest in materials considered not only as ‘true matter’, but also as new breeds where geometry, texture, tooling and finish are able to provoke new sensations when they are applied to a substance. These artificial materials can be described as synthetic because they are the outcome of various qualities that are not necessarily true to the original matter, but they are the combination of two or more parts, whether by design or by natural processes. The aim of this paper is to investigate the potential of architectural surfaces to produce effects through the invention of new breeds of artificial matter, using micro-scale details derived from Nature as an inspiration.

  8. Using multi-polarization C- and L-band synthetic aperture radar to estimate biomass and soil moisture of wheat fields

    Science.gov (United States)

    Hosseini, Mehdi; McNairn, Heather

    2017-06-01

    Biomass and soil moisture are two important parameters for agricultural crop monitoring and yield estimation. In this study, the Water Cloud Model (WCM) was coupled with the Ulaby soil moisture model to estimate both biomass and soil moisture for spring wheat fields in a test site in western Canada. This study exploited both C-band (RADARSAT-2) and L-band (UAVSAR) Synthetic Aperture Radars (SARs) for this purpose. The WCM-Ulaby model was calibrated for three polarizations (HH, VV and HV). Subsequently two of these three polarizations were used as inputs to an inversion procedure, to retrieve either soil moisture or biomass without the need for any ancillary data. The model was calibrated for total canopy biomass, the biomass of only the wheat heads, as well as for different wheat growth stages. This resulted in a calibrated WCM-Ulaby model for each sensor-polarization-phenology-biomass combination. Validation of model retrievals led to promising results. RADARSAT-2 (HH-HV) estimated total wheat biomass with root mean square (RMSE) and mean average (MAE) errors of 78.834 g/m2 and 58.438 g/m2; soil moisture with errors of 0.078 m3/m3 (RMSE) and 0.065 m3/m3 (MAE) are reported. During the period of crop ripening, L-band estimates of soil moisture had accuracies of 0.064 m3/m3 (RMSE) and 0.057 m3/m3 (MAE). RADARSAT-2 (VV-HV) produced interesting results for retrieval of the biomass of the wheat heads. In this particular case, the biomass of the heads was estimated with accuracies of 38.757 g/m2 (RSME) and 33.152 g/m2 (MAE). For wider implementation this model will require additional data to strengthen the model accuracy and confirm estimation performance. Nevertheless this study encourages further research given the importance of wheat as a global commodity, the challenge of cloud cover in optical monitoring and the potential of direct estimation of the weight of heads where wheat production lies.

  9. Synthetic Representation of the Motion of Co-orbitals of the Galilean Satellites

    Science.gov (United States)

    Scott, Bryan; Bills, Bruce

    2015-05-01

    Two of Saturn's satellites (Tethys and Dione) each have two co-orbital companions at their L4 and L5 triangular equilibrium points. This prompts us to ask: do any of Jupiter's Galilean satellites have co-orbitals? In our analysis, the motions of the Galilean satellites are specified by the model E5 of Lieske, truncated to include the dominant terms. This model includes the oblate figure of Jupiter, mutual perturbations between pairs of satellites, and perturbations from Saturn and the Sun. The initial positions and velocities of co-orbital test particles are specified by a rotation of the state vector of the Galilean satellite with which it shares an orbit, on a reference date, through a given angle, and the equations of motion are integrated. Integrations are carried out for 100,000 days, which is several hundred times the longest forcing period. A linearized stability analysis of motion about the L4 or L5 Lagrange points, of the circular restricted three body problem, predicts oscillations in angular separation at two main frequencies. In the six body problem that we consider here, these same frequencies appear, along with characteristic families of harmonics. Numerically integrated co-orbitals trajectories in the rotating frame exhibit the expected tadpole behavior. The Fourier amplitude spectrum of the numerically integrated angular separation between the co-orbital and its parent satellite exhibits two sets of characteristic features. The first set consists of the prominent lines in the spectrum of the variability in satellite mean motion. The second consists of the restricted three body predicted frequencies, and the families of related spectral lines which emerge for pertrubations in the restricted problem. Our integrations suggest that the motion of co-orbitals of the Galilean satellites is well approximated by this simple scheme.

  10. Cosmo Cassette: A Microfluidic Microgravity Microbial System For Synthetic Biology Unit Tests and Satellite Missions

    Science.gov (United States)

    Berliner, Aaron J.

    2013-01-01

    Although methods in the design-build-test life cycle of the synthetic biology field have grown rapidly, the expansion has been non-uniform. The design and build stages in development have seen innovations in the form of biological CAD and more efficient means for building DNA, RNA, and other biological constructs. The testing phase of the cycle remains in need of innovation. Presented will be both a theoretical abstraction of biological measurement and a practical demonstration of a microfluidics-based platform for characterizing synthetic biological phenomena. Such a platform demonstrates a design of additive manufacturing (3D printing) for construction of a microbial fuel cell (MFC) to be used in experiments carried out in space. First, the biocompatibility of the polypropylene chassis will be demonstrated. The novel MFCs will be cheaper, and faster to make and iterate through designs. The novel design will contain a manifold switchingdistribution system and an integrated in-chip set of reagent reservoirs fabricated via 3D printing. The automated nature of the 3D printing yields itself to higher resolution switching valves and leads to smaller sized payloads, lower cost, reduced power and a standardized platform for synthetic biology unit tests on Earth and in space. It will be demonstrated that the application of unit testing in synthetic biology will lead to the automatic construction and validation of desired constructs. Unit testing methodologies offer benefits of preemptive problem identification, change of facility, simplicity of integration, ease of documentation, and separation of interface from implementation, and automated design.

  11. Geometric calibration of ERS satellite SAR images

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Madsen, Søren Nørvang

    2001-01-01

    Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed and calib......Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed...... on a seven-year ERS-1 and a four-year ERS-2 time series, the long term stability is found to be sufficient to allow a single calibration covering the entire mission period. A descending and an ascending orbit tandem pair of the ESA calibration site on Flevoland, suitable for calibration of ERS SAR processors...

  12. Quantifying offshore wind resources from satellite wind maps: Study area the North Sea

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Barthelmie, Rebecca Jane; Christiansen, Merete B.

    2006-01-01

    analysis and application program (WAsP). An estimate of the wind resource at the new project site at Horns Rev is given based on satellite SAR observations. The comparison of offshore satellite scatterometer winds, global model data and in situ data shows good agreement. Furthermore, the wake effect......Offshore wind resources are quantified from satellite synthetic aperture radar (SAR) and satellite scatterometer observations at local and regional scale respectively at the Horns Rev site in Denmark. The method for wind resource estimation from satellite observations interfaces with the wind atlas...

  13. Using Sentinel-1 SAR satellites to map wind speed variation across offshore wind farm clusters

    Science.gov (United States)

    James, S. F.

    2017-11-01

    Offshore wind speed maps at 500m resolution are derived from freely available satellite Synthetic Aperture Radar (SAR) data. The method for processing many SAR images to derive wind speed maps is described in full. The results are tested against coincident offshore mast data. Example wind speed maps for the UK Thames Estuary offshore wind farm cluster are presented.

  14. Structural aspects of SAR antenna for Japanese Earth Resources Satellite 1

    Science.gov (United States)

    Mitsuma, H.

    1984-09-01

    Research and development to establish the basic technology of Synthetic Aperture Radar (SAR) for the Japanese Earth Resources Satellite-1 are described. The solar array paddle technologies (honeycomb sandwich panel and deployment mechanism) were applied to the SAR antenna. Structural and mechanical component tests, and thermal distortion tests are discussed.

  15. Small aperture earth station networks and their relationship to ISDN

    Science.gov (United States)

    Golding, Leonard S.

    Applications of satellite networks involving the use of small-aperture antennas and low-cost earth stations located at customer-premises sites are considered. Such VSAT (very small-aperture satellite) networks are beginning to be installed in domestic satellite neworks as well as internationally in INTELSAT, IBS, Internet, and VIST offerings. The way in which VSAT networks might be integrated into ISDN (an integrated services digital network) is considered. The integration of mobile satellite networks is also considered.

  16. A case of timely satellite image acquisitions in support of coastal emergency environmental response management

    Science.gov (United States)

    Ramsey, Elijah W.; Werle, Dirk; Lu, Zhong; Rangoonwala, Amina; Suzuoki, Yukihiro

    2009-01-01

    The synergistic application of optical and radar satellite imagery improves emergency response and advance coastal monitoring from the realm of “opportunistic” to that of “strategic.” As illustrated by the Hurricane Ike example, synthetic aperture radar imaging capabilities are clearly applicable for emergency response operations, but they are also relevant to emergency environmental management. Integrated with optical monitoring, the nearly real-time availability of synthetic aperture radar provides superior consistency in status and trends monitoring and enhanced information concerning causal forces of change that are critical to coastal resource sustainability, including flooding extent, depth, and frequency.

  17. Sea ice monitoring in the northern sea route by satellite radar data

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, O.M.; Sandven, S.; Pettersson, L.H. [and others

    1997-06-01

    A project to implement satellite monitoring of ice in the Northern Sea Route between the Barents Sea and the Bering Strait is described. The project objectives are to support ice navigation, offshore oil exploration and production, and global climate change studies. Satellite monitoring will include synthetic-aperture radar, sidelooking radar, and other remote sensing data. The joint project between the Russian Space Agency and the European Space Agency is outlined, and major project elements are described.

  18. 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.

  19. An FSS-Backed 20/30 GHz Circularly Polarized Reflectarray for a Shared Aperture L- and Ka-Band Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst; Gothelf, Ulrich; Kim, Oleksiy S.

    2014-01-01

    manufactured at the Technical University of Denmark (DTU) and measured at the DTU-ESA Spherical Near-Field Antenna Test Facility. The reflectarray provides a maximum directivity of 36.4 and 38.5 dBi at 20.0 and 29.8 GHz, respectively, and an aperture illumination efficiency in the two frequency bands up to 57......% and 48%, respectively. There is very little degradation in the L-band patch array performance due to the reflectarray, and it provides a minimum directivity of 11.8 dBi over the L-band....

  20. Aperture area measurement facility

    Data.gov (United States)

    Federal Laboratory Consortium — NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of...

  1. Land Cover Characterization and Classification of Arctic Tundra Environments by Means of Polarized Synthetic Aperture X- and C-Band Radar (PolSAR and Landsat 8 Multispectral Imagery — Richards Island, Canada

    Directory of Open Access Journals (Sweden)

    Tobias Ullmann

    2014-09-01

    Full Text Available In this work the potential of polarimetric Synthetic Aperture Radar (PolSAR data of dual-polarized TerraSAR-X (HH/VV and quad-polarized Radarsat-2 was examined in combination with multispectral Landsat 8 data for unsupervised and supervised classification of tundra land cover types of Richards Island, Canada. The classification accuracies as well as the backscatter and reflectance characteristics were analyzed using reference data collected during three field work campaigns and include in situ data and high resolution airborne photography. The optical data offered an acceptable initial accuracy for the land cover classification. The overall accuracy was increased by the combination of PolSAR and optical data and was up to 71% for unsupervised (Landsat 8 and TerraSAR-X and up to 87% for supervised classification (Landsat 8 and Radarsat-2 for five tundra land cover types. The decomposition features of the dual and quad-polarized data showed a high sensitivity for the non-vegetated substrate (dominant surface scattering and wetland vegetation (dominant double bounce and volume scattering. These classes had high potential to be automatically detected with unsupervised classification techniques.

  2. 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.

  3. Performance of PolSAR backscatter and PolInSAR coherence for scattering characterization of forest vegetation using single pass X-band spaceborne synthetic aperture radar data

    Science.gov (United States)

    Joshi, Sushil Kumar; Kumar, Shashi

    2017-04-01

    Airborne synthetic aperture radar (SAR) data have been successfully used for forest height inversion; however, there is limited applicability in spaceborne scenarios due to high temporal decorrelation. This study investigates the potential of a high-resolution fully polarimetric interferometric pair of TerraSAR-X/TanDEM-X SAR data with no temporal decorrelation to analyze the backscatter and coherence response and to implement polarimetric SAR interferometry-based height inversion algorithms. The data were acquired over Barkot forest region of Uttarakhand state in India. Yamaguchi decomposition was implemented onto the dataset to express total backscatter as a sum of different scattering components from a single SAR resolution cell. Coherency matrix was used to compute complex coherence for different polarization channels. Forest areas suffered from low coherence due to volume decorrelation, whereas a dry river bed had shown high coherence. The coherence amplitude inversion approach overestimated the forest height and also resulted in false heights for this dry river bed. These limitations were overcome by implementing three-stage inversion modeling, which assumes polarization-independent volume coherence. The results were validated using ground truth data available for 49 plots, and the latter was found to be more accurate with an overall accuracy of 90.15% and root-mean-square error of 2.42 m.

  4. Spatiotemporal evolution of surface creep in the Parkfield region of the San Andreas Fault (1993-2004) from synthetic aperture radar

    Science.gov (United States)

    de Michele, M.; Raucoules, D.; Rolandone, F.; Briole, P.; Salichon, J.; Lemoine, A.; Aochi, H.

    2011-08-01

    The Parkfield section of the San Andreas Fault (SAF) is defined as a transitional portion of the fault between slip-release behavior types in the creeping section of the SAF to the northwest and the apparently locked section to the southeast. The Parkfield section is characterized by complex frictional fault behavior because it represents a transition zone from aseismic creep to stick-slip regime. At least six historic earthquakes of M w ~ 6 have occurred in this area in 1881, 1901, 1922, 1934, 1966, and 2004. It was observed in the 2004 M w 6.0 Parkfield earthquake that ~ 70% of the total (coseismic and postseismic) moment release occurred aseismically. To understand the SAF behavior in this area, it is of particular interest to measure and analyze, not only the spatial evolution of the surface displacement in this area, but also its evolution over time. Using radar data acquired by the European Space Agency's European Remote Sensing (ERS1-2) satellites, we constructed descending interferograms and retrieved time series of surface displacements along the central SAF for the decade preceding the 2004 Parkfield earthquake. We focus on characterizing the space and time evolution of surface creep in the Parkfield and Cholame sections. The spatial pattern of the interseismic displacement rate indicates that tectonic strain was not uniformly distributed along the strike of the fault between 1993 and 2004. Our data indicate not only a decrease in the creep rate from the Parkfield section to south of Highway-46 from 1.4 ± 0.3 cm/yr to 0.6 ± 0.3 cm/yr, but also a small but significant creep-rate increase in the Cholame section to 0.2 ± 0.1 cm/yr. The evidence for episodic creep in the Cholame section of the SAF south-east of Parkfield is in contrast with previously published interpretations of GPS and trilateration data. The Cholame section of the SAF merits close monitoring because it was likely the nucleation site of the 1857 Fort Tejón earthquake and because it has

  5. Optimizing coverage and revisit time in sparse military satellite constellations a comparison of traditional approaches and genetic algorithms

    OpenAIRE

    Parish, Jason A.

    2004-01-01

    Sparse military satellite constellations were designed using two methods: a traditional approach and a genetic algorithm. One of the traditional constellation designs was the Discoverer II space based radar. Discoverer II was an 8 plane, 24 satellite, Low Earth Orbit (LEO), Walker constellation designed to provide high-range resolution ground moving target indication (HRR-GMTI), synthetic aperture radar (SAR) imaging and high resolution digital terrain mapping. The traditional method designed...

  6. An L-band interferometric synthetic aperture radar study on the Ganos section of the north Anatolian fault zone between 2007 and 2011: Evidence for along strike segmentation and creep in a shallow fault patch.

    Science.gov (United States)

    de Michele, Marcello; Ergintav, Semih; Aochi, Hideo; Raucoules, Daniel

    2017-01-01

    We utilize L-band interferometric synthetic aperture radar (InSAR) data in this study to retrieve a ground velocity map for the near field of the Ganos section of the north Anatolian fault (NAF) zone. The segmentation and creep distribution of this section, which last ruptured in 1912 to generate a moment magnitude (Mw)7.3 earthquake, remains incompletely understood. Because InSAR processing removes the mean orbital plane, we do not investigate large scale displacements due to regional tectonics in this study as these can be determined using global positioning system (GPS) data, instead concentrating on the close-to-the-fault displacement field. Our aim is to determine whether, or not, it is possible to retrieve robust near field velocity maps from stacking L-band interferograms, combining both single and dual polarization SAR data. In addition, we discuss whether a crustal velocity map can be used to complement GPS observations in an attempt to discriminate the present-day surface displacement of the Ganos fault (GF) across multiple segments. Finally, we characterize the spatial distribution of creep on shallow patches along multiple along-strike segments at shallow depths. Our results suggest the presence of fault segmentation along strike as well as creep on the shallow part of the fault (i.e. the existence of a shallow creeping patch) or the presence of a smoother section on the fault plane. Data imply a heterogeneous fault plane with more complex mechanics than previously thought. Because this study improves our knowledge of the mechanisms underlying the GF, our results have implications for local seismic hazard assessment.

  7. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Melting ice is a tracer in this case. Shear cyclonic elements at the south- ern and eastern parts of the eddy periphery are well seen in both images. In a time of 3 days between the images the eddy shape and spatial ori- entation were not changed, however displacement of shear elements at its periphery in the direc-.

  8. Tissue Harmonic Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Rasmussen, Joachim; Jensen, Jørgen Arendt

    2014-01-01

    with THI improves the image qual- ity compared to DRF-THI. The major benet of SASB is a reduced bandwidth between the probe and processing unit. A BK Medical 2202 Ultraview ultrasound scanner was used to acquire beamformed RF data for oine evaluation. The acquisition was made interleaved between methods...

  9. Velocity estimation using synthetic aperture imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    correlating RF lines from two successive emissions n and n + 1, and then average over a number of lines. In the new approach images n and n + N, n + 1 and n + N + 1 are cross correlated, where N is the number of emissions for one image. These images experience the same phase distortion due to motion...... from the measurements for the same setup exhibit a larger bias -11%, but the standard deviation is comparable to the simulations (sigma similar to 2.5%)....

  10. Clinical evaluation of synthetic aperture sequential beamforming

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Hemmsen, Martin Christian; Lange, Theis

    2012-01-01

    of the ultrasound beam. Five ultrasound experts (radiologists) evaluated the sequence pairs in a side-by-side comparison, and the results show that image quality using SASB was better than conventional B-mode imaging. 73 % of the evaluations favored SASB, and a probability of 70 % was calculated for a new...... time massively reduce the amount of generated data. SASB was implemented in a system consisting of a conventional ultrasound scanner connected to a PC via a research interface. This setup enables simultaneous recording with both SASB and conventional technique. Eighteen volunteers were ultrasound...... scanned abdominally, and 84 sequence pairs were recorded. Each sequence pair consists of two simultaneous recordings of the same anatomical location with SASB and conventional B-mode imaging. The images were evaluated in terms of spatial resolution, contrast, unwanted artifacts, and penetration depth...

  11. 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...

  12. Synthetic Aperture Ladar Imaging and Atmospheric Turbulence

    Science.gov (United States)

    2016-06-09

    Phase Detectors Task 2.1: Design and build reference targets Figure 6 is a picture of the raging/imaging system on a small wheeled optical table...at https://www.osapublishing.org/abstract.cfm?URI=oe-23-18-23811 (Z.W. Barber’s contributions). 2. New discoveries, inventions , or patent disclosures...Do you have any discoveries, inventions , or patent disclosures to report for this period? No Please describe and include any notable dates Do you plan

  13. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    ... 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 ...

  14. Automated Change Detection for Synthetic Aperture Sonar

    Science.gov (United States)

    2014-01-01

    5] L. Lemieux, U. Wieshmann, N. Moran, D. Fish, and S. Shorvon, “The detection and significance of subtle changes in mixed-signal brain lesions by...D. Gounot, and L. Rumbach, “ Automatic change detection in multimodal serial MRI: Application to multiple sclerosis lesion evolution,” NeuroImage 20...development by the SAR community since at least the 1990s,3 and procedures to fuse scene changes derived from segmented features with pixel or parcel based

  15. Geometric Calibration and Accuracy Verification of the GF-3 Satellite.

    Science.gov (United States)

    Zhao, Ruishan; Zhang, Guo; Deng, Mingjun; Xu, Kai; Guo, Fengcheng

    2017-08-29

    The GF-3 satellite is the first multi-polarization synthetic aperture radar (SAR) imaging satellite in China, which operates in the C band with a resolution of 1 m. Although the SAR satellite system was geometrically calibrated during the in-orbit commissioning phase, there are still some system errors that affect its geometric positioning accuracy. In this study, these errors are classified into three categories: fixed system error, time-varying system error, and random error. Using a multimode hybrid geometric calibration of spaceborne SAR, and considering the atmospheric propagation delay, all system errors can be effectively corrected through high-precision ground control points and global atmospheric reference data. The geometric calibration experiments and accuracy evaluation for the GF-3 satellite are performed using ground control data from several regions. The experimental results show that the residual system errors of the GF-3 SAR satellite have been effectively eliminated, and the geometric positioning accuracy can be better than 3 m.

  16. Satellite Survey of Inner Seas: Oil Pollution in the Black and Caspian Seas

    OpenAIRE

    Marina Mityagina; Olga Lavrova

    2016-01-01

    The paper discusses our studies of oil pollution in the Black and Caspian Seas. The research was based on a multi-sensor approach on satellite survey data. A combined analysis of oil film signatures in satellite synthetic aperture radar (SAR) and optical imagery was performed. Maps of oil spills detected in satellite imagery of the whole aquatic area of the Black Sea and the Middle and the Southern Caspian Sea are created. Areas of the heaviest pollution are outlined. It is shown that the mai...

  17. 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....

  18. Extrapolating Satellite Winds to Turbine Operating Heights

    DEFF Research Database (Denmark)

    Badger, Merete; Pena Diaz, Alfredo; Hahmann, Andrea N.

    2016-01-01

    Ocean wind retrievals from satellite sensors are typically performed for the standard level of 10 m. This restricts their full exploitation for wind energy planning, which requires wind information at much higher levels where wind turbines operate. A new method is presented for the vertical......-term stability correction that is based on numerical weather prediction (NWP) model outputs. The effect of the long-term stability correction on the wind profile is significant. The method is applied to Envisat Advanced Synthetic Aperture Radar scenes acquired over the south Baltic Sea. This leads to maps...

  19. Topaz II Nuclear Powered SAR Satellite

    OpenAIRE

    Feuerstein, M.; Agrawal, B.N.

    1994-01-01

    The article of record as published may be found at http://dx.doi.org/10.2514/6.1994-4688 The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth scie...

  20. Synthetized tropospheric total attenuation time series for satellite-to-aeronautical link from L to Q band

    OpenAIRE

    Graziani, Alberto; Vanhoenacker-Janvier, Danielle; Pereira, Carlos; Riva, Carlo; Vergani, Alessandro; Lemorton, Joel; 11th European Conference on Antennas and Propagation (EuCAP 2017)

    2016-01-01

    The synthetized attenuation time series together with the Complementary Cumulative Distribution Function of attenuation values play a crucial role for the design and validation of communication systems. ITU-R recommendations propose different models to characterize the channels. In particular, the ITU-R P1853 recommendation proposes a methodology for the synthesis of attenuation time series for ground stations. Starting from this recommendation and combining different recommendations and exte...