WorldWideScience

Sample records for base em radar

  1. Plasma-based radar cross section reduction

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents a comprehensive review of plasma-based stealth, covering the basics, methods, parametric analysis, and challenges towards the realization of the idea. The concealment of aircraft from radar sources, or stealth, is achieved through shaping, radar absorbing coatings, engineered materials, or plasma, etc. Plasma-based stealth is a radar cross section (RCS) reduction technique associated with the reflection and absorption of incident electromagnetic (EM) waves by the plasma layer surrounding the structure. A plasma cloud covering the aircraft may give rise to other signatures such as thermal, acoustic, infrared, or visual. Thus it is a matter of concern that the RCS reduction by plasma enhances its detectability due to other signatures. This needs a careful approach towards the plasma generation and its EM wave interaction. The book starts with the basics of EM wave interactions with plasma, briefly discuss the methods used to analyze the propagation characteristics of plasma, and its generatio...

  2. MST radar data-base management

    Science.gov (United States)

    Wickwar, V. B.

    1983-01-01

    Data management for Mesospheric-Stratospheric-Tropospheric, (MST) radars is addressed. An incoherent-scatter radar data base is discussed in terms of purpose, centralization, scope, and nature of the data base management system.

  3. Space Based Radar To Observe Space Debris

    OpenAIRE

    Tolkachev, A.A.; Zolotarev, M.M.; Loukiaschenko, V.I.; Raikunov, G.G.; Yaremenko, A.I.

    1998-01-01

    Space debris of 1÷3mm size is known to be hazardous for astronauts and space vehicles. At the same time the possibility to notice such objects by ground based optical and radar devices in the nearest future is rather problematic. Here we propose an idea of space radar for observation of cicumterrestrial space debris. The radar works in short wave part of millimetre band, which is mostly suitable for this purpose. The radar provides detecting and tracking of 1mm size objects within 40000m2 are...

  4. Knowledge Based Systems and Metacognition in Radar

    Science.gov (United States)

    Capraro, Gerard T.; Wicks, Michael C.

    An airborne ground looking radar sensor's performance may be enhanced by selecting algorithms adaptively as the environment changes. A short description of an airborne intelligent radar system (AIRS) is presented with a description of the knowledge based filter and detection portions. A second level of artificial intelligence (AI) processing is presented that monitors, tests, and learns how to improve and control the first level. This approach is based upon metacognition, a way forward for developing knowledge based systems.

  5. Radar-based hail detection

    Czech Academy of Sciences Publication Activity Database

    Skripniková, Kateřina; Řezáčová, Daniela

    2014-01-01

    Roč. 144, č. 1 (2014), s. 175-185. ISSN 0169-8095 R&D Projects: GA ČR(CZ) GAP209/11/2045; GA MŠk LD11044 Institutional support: RVO:68378289 Keywords : hail detection * weather radar * hail damage risk Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.844, year: 2014 http://www.sciencedirect.com/science/article/pii/S0169809513001804

  6. Probabilistic forecasts based on radar rainfall uncertainty

    Science.gov (United States)

    Liguori, S.; Rico-Ramirez, M. A.

    2012-04-01

    The potential advantages resulting from integrating weather radar rainfall estimates in hydro-meteorological forecasting systems is limited by the inherent uncertainty affecting radar rainfall measurements, which is due to various sources of error [1-3]. The improvement of quality control and correction techniques is recognized to play a role for the future improvement of radar-based flow predictions. However, the knowledge of the uncertainty affecting radar rainfall data can also be effectively used to build a hydro-meteorological forecasting system in a probabilistic framework. This work discusses the results of the implementation of a novel probabilistic forecasting system developed to improve ensemble predictions over a small urban area located in the North of England. An ensemble of radar rainfall fields can be determined as the sum of a deterministic component and a perturbation field, the latter being informed by the knowledge of the spatial-temporal characteristics of the radar error assessed with reference to rain-gauges measurements. This approach is similar to the REAL system [4] developed for use in the Southern-Alps. The radar uncertainty estimate can then be propagated with a nowcasting model, used to extrapolate an ensemble of radar rainfall forecasts, which can ultimately drive hydrological ensemble predictions. A radar ensemble generator has been calibrated using radar rainfall data made available from the UK Met Office after applying post-processing and corrections algorithms [5-6]. One hour rainfall accumulations from 235 rain gauges recorded for the year 2007 have provided the reference to determine the radar error. Statistics describing the spatial characteristics of the error (i.e. mean and covariance) have been computed off-line at gauges location, along with the parameters describing the error temporal correlation. A system has then been set up to impose the space-time error properties to stochastic perturbations, generated in real-time at

  7. UAS-Based Radar Sounding of Ice

    Science.gov (United States)

    Hale, R. D.; Keshmiri, S.; Leuschen, C.; Ewing, M.; Yan, J. B.; Rodriguez-Morales, F.; Gogineni, S.

    2014-12-01

    The University of Kansas Center for Remote Sensing of Ice Sheets developed two Unmanned Aerial Systems (UASs) to support polar research. We developed a mid-range UAS, called the Meridian, for operating a radar depth sounder/imager at 195 MHz with an eight-element antenna array. The Meridian weighs 1,100 lbs, has a 26-foot wingspan, and a range of 950 nm at its full payload capacity of 120 lbs. Ice-penetrating radar performance drove the configuration design, though additional payloads and sensors were considered to ensure adaptation to multi-mission science payloads. We also developed a short range UAS called the G1X for operating a low-frequency radar sounder that operates at 14 and 35 MHz. The G1X weighs 85 lbs, has a 17-foot wingspan, and a range of about 60 nm per gallon of fuel. The dual-frequency HF/VHF radar depth sounder transmits at 100 W peak power at a pulse repetition frequency of 10 KHz and weighs approximately 4.5 lbs. We conducted flight tests of the G1X integrated with the radar at the Sub-glacial Lake Whillans ice stream and the WISSARD drill site. The tests included pilot-controlled and fully autonomous flights to collect data over closely-spaced lines to synthesize a 2-D aperture. We obtained clear bed echoes with a signal-to-noise (S/N) ratio of more than 50 dB at this location. These are the first-ever successful soundings of glacial ice with a UAS-based radar. Although ice attenuation losses in this location are low in comparison to more challenging targets, in-field performance improvements to the UAS and HF/VHF radar system enabled significant gains in the signal-to-noise ratio, such that the system can now be demonstrated on more challenging outlet glaciers. We are upgrading the G1X UAS and radar system for further tests and data collection in Greenland. We are reducing the weight and volume of the radar, which, when coupled with further reductions in airframe and avionics weight and a larger fuel bladder, will offer extended range. Finally

  8. Validation of GPM Ka-Radar Algorithm Using a Ground-based Ka-Radar System

    Science.gov (United States)

    Nakamura, Kenji; Kaneko, Yuki; Nakagawa, Katsuhiro; Furukawa, Kinji; Suzuki, Kenji

    2016-04-01

    GPM led by the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration of US (NASA) aims to observe global precipitation. The core satellite is equipped with a microwave radiometer (GMI) and a dual-frequency radar (DPR) which is the first spaceborne Ku/Ka-band dual-wavelength radar dedicated for precipitation measurement. In the DPR algorithm, measured radar reflectivity is converted to effective radar reflectivity by estimating the rain attenuation. Here, the scattering/attenuation characteristics of Ka-band radiowaves are crucial, particularly for wet snow. A melting layer observation using a dual Ka-band radar system developed by JAXA was conducted along the slope of Mt. Zao in Yamagata Prefecture, Japan. The dual Ka-band radar system consists of two nearly identical Ka-band FM-CW radars, and the precipitation systems between two radars were observed in opposite directions. From this experiment, equivalent radar reflectivity (Ze) and specific attenuation (k) were obtained. The experiments were conducted for two winter seasons. During the data analyses, it was found that k estimate easily fluctuates because the estimate is based on double difference calculation. With much temporal and spatial averaging, k-Ze relationship was obtained for melting layers. One of the results is that the height of the peak of k seems slightly higher than that of Ze. The results are compared with in-situ precipitation particle measurements.

  9. Comparison of Precipitation Observations from a Prototype Space-based Cloud Radar and Ground-based Radars

    Institute of Scientific and Technical Information of China (English)

    LIU Liping; ZHANG Zhiqiang; YU Danru; YANG Hu; ZHAO Chonghui; ZHONG Lingzhi

    2012-01-01

    A prototype space-based cloud radar has been developed and was installed on an airplane to observe a precipitation system over Tianjin,China in July 2010.Ground-based S-band and Ka-band radars were used to examine the observational capability of the prototype. A cross-comparison algorithm between different wavelengths,spatial resolutions and platform radars is presented.The reflectivity biases,correlation coefficients and standard deviations between the radars are analyzed.The equivalent reflectivity bias between the S- and Ka-band radars were simulated with a given raindrop size distribution.The results indicated that reflectivity bias between the S- and Ka-band radars due to scattering properties was less than 5 dB,and for weak precipitation the bias was negligible. The prototype space-based cloud radar was able to measure a reasonable vertical profile of reflectivity,but the reflectivity below an altitude of 1.5 km above ground level was obscured by ground clutter.The measured reflectivity by the prototype space-based cloud radar was approximately 10.9 dB stronger than that by the S-band Doppler radar (SA radar),and 13.7 dB stronger than that by the ground-based cloud radar.The reflectivity measured by the SA radar was 0.4 dB stronger than that by the ground-based cloud radar.This study could provide a method for the quantitative examination of the observation ability for space-based radars.

  10. Assimilation of radar-based nowcast into HIRLAM NWP model

    DEFF Research Database (Denmark)

    Jensen, David Getreuer; Petersen, Claus; Rasmussen, Michael R.

    2015-01-01

    The present study introduces a nowcast scheme that assimilates radar extrapolation data (RED) into a nowcasting version of the high resolution limited area model (HIRLAM) numerical weather prediction (NWP) model covering the area of Denmark. The RED are based on the Co-TREC (tracking radar echoes...... by correlation) methodology and are generated from cleaned radar mosaics from the Danish weather radar network. The assimilation technique is a newly developed method that increases model precipitation by increasing low-level convergence and decreasing convergence aloft in order to increase the...

  11. Mutual information-based LPI optimisation for radar network

    Science.gov (United States)

    Shi, Chenguang; Zhou, Jianjiang; Wang, Fei; Chen, Jun

    2015-07-01

    Radar network can offer significant performance improvement for target detection and information extraction employing spatial diversity. For a fixed number of radars, the achievable mutual information (MI) for estimating the target parameters may extend beyond a predefined threshold with full power transmission. In this paper, an effective low probability of intercept (LPI) optimisation algorithm is presented to improve LPI performance for radar network. Based on radar network system model, we first provide Schleher intercept factor for radar network as an optimisation metric for LPI performance. Then, a novel LPI optimisation algorithm is presented, where for a predefined MI threshold, Schleher intercept factor for radar network is minimised by optimising the transmission power allocation among radars in the network such that the enhanced LPI performance for radar network can be achieved. The genetic algorithm based on nonlinear programming (GA-NP) is employed to solve the resulting nonconvex and nonlinear optimisation problem. Some simulations demonstrate that the proposed algorithm is valuable and effective to improve the LPI performance for radar network.

  12. Single Frequency Network Based Distributed Passive Radar Technology

    Directory of Open Access Journals (Sweden)

    Wan Xian-rong

    2015-01-01

    Full Text Available The research and application of passive radar are heading from single transmitter-receiver pair to multiple transmitter-receiver pairs. As an important class of the illuminators of opportunity, most of modern digital broadcasting and television systems work on Single Frequency Network (SFN, which intrinsically determines that the passive radar based on such illuminators must be distributed and networked. In consideration of the remarkable working and processing mode of passive radar under SFN configuration, this paper proposes the concept of SFN-based Distributed Passive Radar (SDPR. The main characteristics and key problems of SDPR are first described. Then several potential solutions are discussed for part of the key technologies. The feasibility of SDPR is demonstrated by preliminary experimental results. Finally, the concept of four network convergence that includes the broadcast based passive radar network is conceived, and its application prospects are discussed.

  13. Oblique Projection Polarization Filtering-Based Interference Suppressions for Radar Sensor Networks

    Directory of Open Access Journals (Sweden)

    Cao Bin

    2010-01-01

    Full Text Available The interferences coming from the radar members degrade the detection and recognition performance of the radar sensor networks (RSNs if the waveforms of the radar members are nonorthogonal. In this paper, we analyze the interferences by exploring the polarization information of the electromagnetic (EM waves. Then, we propose the oblique projection polarization filtering- (OPPF- based scheme to suppress the interferences while keeping the amplitude and phase of its own return in RSNs, even if the polarized states of the radar members are not orthogonal. We consider the cooperative RSNs environment where the polarization information of each radar member is known to all. The proposed method uses all radar members' polarization information to establish the corresponding filtering operator. The Doppler-shift and its uncertainty are independent of the polarization information, which contributes that the interferences can be suppressed without the utilization of the spatial, the temporal, the frequency, the time-delay and the Doppler-shift information. Theoretical analysis and the mathematical deduction show that the proposed scheme is a valid and simple implementation. Simulation results also demonstrate that this method can obtain a good filtering performance when dealing with the problem of interference suppressions for RSNs.

  14. The evaluation of satellite-borne weather radar system designs using real ground-based radar data

    Science.gov (United States)

    Dobson, E. B.; Kalshoven, J. E., Jr.

    1977-01-01

    The paper presents method of evaluating proposed satellite radar systems using real radar data, and discusses methods of displaying the results which will hopefully facilitate easy comparison of systems. A single pencil beam pulsed radar system is considered while the precipitation data base comes from six rain days observed by SPANDAR. The many additional factors that must be considered in the radar equation such as attenuation and scattering (Mie and Rayleigh) are discussed along with some indication where possible errors lie.

  15. Testing radar-based hail detection criteria

    Czech Academy of Sciences Publication Activity Database

    Skripniková, Kateřina; Řezáčová, Daniela

    Toulouse : Météo France, 2012. [ERAD 2012 - European Conference on Radar in Meteorology and Hydrology /7./. Toulouse (FR), 24.06.2012-29.06.2012] R&D Projects: GA ČR(CZ) GAP209/11/2045; GA MŠk LD11044 Institutional support: RVO:68378289 Keywords : hail detection * weather radar * damaging hailstorms Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.meteo.fr/cic/meetings/2012/ERAD/extended_abs/NOW_367_ext_abs.pdf

  16. Radar Scan Strategies for the Patrick Air Force Base Weather Surveillance Radar, Model-74C, Replacement

    Science.gov (United States)

    Short, David

    2008-01-01

    The 45th Weather Squadron (45 WS) is replacing the Weather Surveillance Radar, Model 74C (WSR-74C) at Patrick Air Force Base (PAFB), with a Doppler, dual polarization radar, the Radtec 43/250. A new scan strategy is needed for the Radtec 43/250, to provide high vertical resolution data over the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) launch pads, while taking advantage of the new radar's advanced capabilities for detecting severe weather phenomena associated with convection within the 45 WS area of responsibility. The Applied Meteorology Unit (AMU) developed several scan strategies customized for the operational needs of the 45 WS. The AMU also developed a plan for evaluating the scan strategies in the period prior to operational acceptance, currently scheduled for November 2008.

  17. Detecting weather radar clutter using satellite-based nowcasting products

    DEFF Research Database (Denmark)

    Jensen, Thomas B.S.; Gill, Rashpal S.; Overgaard, Søren;

    2006-01-01

    This contribution presents the initial results from experiments with detection of weather radar clutter by information fusion with satellite based nowcasting products. Previous studies using information fusion of weather radar data and first generation Meteosat imagery have shown promising results...... for the detecting and removal of clutter. Naturally, the improved spatio-temporal resolution of the Meteosat Second Generation sensors, coupled with its increased number of spectral bands, is expected to yield even better detection accuracies. Weather radar data from three C-band Doppler weather radars...... Application Facility' of EUMETSAT and is based on multispectral images from the SEVIRI sensor of the Meteosat-8 platform. Of special interest is the 'Precipitating Clouds' product, which uses the spectral information coupled with surface temperatures from Numerical Weather Predictions to assign probabilities...

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

    OpenAIRE

    Shuanghui Zhang; Yongxiang Liu; Xiang Li; Guoan Bi

    2016-01-01

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

  19. Detecting weather radar clutter using satellite-based nowcasting products

    OpenAIRE

    Jensen, Thomas B. S.; Gill, Rashpal S.; Overgaard, Søren; Hansen, Lars Kai; Nielsen, Allan Aasbjerg

    2006-01-01

    This contribution presents the initial results from experiments with detection of weather radar clutter by information fusion with satellite based nowcasting products. Previous studies using information fusion of weather radar data and first generation Meteosat imagery have shown promising results for the detecting and removal of clutter. Naturally, the improved spatio-temporal resolution of the Meteosat Second Generation sensors, coupled with its increased number of spectral bands, is expect...

  20. Improved Minimum Detectable Velocity in Bistatic Space-Based Radar

    Institute of Scientific and Technical Information of China (English)

    LI Hua; TANG Jun; PENG Yingning

    2008-01-01

    Single orbit bistatic space-based radar (SBR) is composed of two radars in the same orbit. The characteristics of the clutter Doppler-angle spectrum of a single orbit bistatic SBR show that the slope of the mainbeam clutter spectrum is highly sensitive to the cone angles. Therefore, the minimum detectable veloc-ity of the bistatic system is dependent on the cone angle. Then a new combined working mode of single-orbit bistatic SBR system was developed in which one radar will act as the transmitter and another as the receiver to improve detection performance for all angles. Simulation results by space-time adaptive process-ing verify the improved detection performance. The new design also reduces the average power of each ra-dar system and the size and weight of the on-board solar array-battery system.

  1. 3D downscaling model for radar-based precipitation fields

    Energy Technology Data Exchange (ETDEWEB)

    Llort, X.; Berenguer, M.; Franco, M.; Sanchez-Diezma, R.; Sempere-Torres, D. [Grup de Recerca Aplicada en Hidrometeorologia, Univ. Politecnica de Catalunya (Spain)

    2006-10-15

    The generating of rainfall fields with a higher resolution than so far observed and with realistic features is a challenge with multiple applications. In particular it could be useful to quantify the uncertainty introduced by the different sources of error affecting radar measurements, in a controlled simulation framework. This paper proposes a method to generate three-dimensional high-resolution rainfall fields based on downscaling meteorological radar data. The technique performs a scale analysis of the first radar tilt field combining a wavelet model with Fourier analysis. In order to downscale the upper radar elevations and with the aim of preserving the vertical structure, a homotopy of the observed vertical profiles of reflectivity is performed. Preliminary evaluation of the technique shows that it is able to generate realistic extreme values and, at the same time, partially reproduce the structure of small scales. (orig.)

  2. A fully photonics-based coherent radar system.

    Science.gov (United States)

    Ghelfi, Paolo; Laghezza, Francesco; Scotti, Filippo; Serafino, Giovanni; Capria, Amerigo; Pinna, Sergio; Onori, Daniel; Porzi, Claudio; Scaffardi, Mirco; Malacarne, Antonio; Vercesi, Valeria; Lazzeri, Emma; Berizzi, Fabrizio; Bogoni, Antonella

    2014-03-20

    The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today's digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system. PMID:24646997

  3. An Innovative Transponder-Based Interferometric Radar for Vibration Measurements

    International Nuclear Information System (INIS)

    Ground-based radar interferometry has recently emerged as an innovative technology of remote sensing, able to accurately measure the static or dynamic displacement of several points of a structure. This technique in the last couple of years has been applied to different types of structures, such as bridges, towers and chimneys. This paper presents a prototype system developed by IDS, originally aimed at measuring the structural vibrations of helicopter rotor blades, based on an interferometric technique and constituted by combination of a radar sensor and a series of transponders installed on the target structure. The main advantages of this solution with respect to conventional interferometric radars, are related to the increased spatial resolution of the system, provided by the possibility to discriminate different transponders installed within the same resolution cell of the radar sensor, and to the reduction of the ambient noise (e.g. multi-path) on the radar measurement. The first feature allows the use of the microwave technology even on target areas with limited dimensions, such as industrial facilities, while the second aspect may extend the use of radar interferometric systems to complex scenarios, where multi-reflections are expected due to the presence of natural targets with high reflectivity to the radar signal. In the paper, the system and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a lab set-up is summarized. Then the data acquired on a rotating mock-up are reported and analyzed to identify natural frequencies and mode shapes of the investigated structure.

  4. An Innovative Transponder-Based Interferometric Radar for Vibration Measurements

    Science.gov (United States)

    Coppi, F.; Cerutti, A.; Farina, P.; De Pasquale, G.; Novembrini, G.

    2010-05-01

    Ground-based radar interferometry has recently emerged as an innovative technology of remote sensing, able to accurately measure the static or dynamic displacement of several points of a structure. This technique in the last couple of years has been applied to different types of structures, such as bridges, towers and chimneys. This paper presents a prototype system developed by IDS, originally aimed at measuring the structural vibrations of helicopter rotor blades, based on an interferometric technique and constituted by combination of a radar sensor and a series of transponders installed on the target structure. The main advantages of this solution with respect to conventional interferometric radars, are related to the increased spatial resolution of the system, provided by the possibility to discriminate different transponders installed within the same resolution cell of the radar sensor, and to the reduction of the ambient noise (e.g. multi-path) on the radar measurement. The first feature allows the use of the microwave technology even on target areas with limited dimensions, such as industrial facilities, while the second aspect may extend the use of radar interferometric systems to complex scenarios, where multi-reflections are expected due to the presence of natural targets with high reflectivity to the radar signal. In the paper, the system and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a lab set-up is summarized. Then the data acquired on a rotating mock-up are reported and analyzed to identify natural frequencies and mode shapes of the investigated structure.

  5. Relationship between Cloud Characteristics and Radar Reflectivity Based on Aircraft and Cloud Radar Co-observations

    Institute of Scientific and Technical Information of China (English)

    ZONG Rong; LIU Liping; YIN Yan

    2013-01-01

    Cloud properties were investigated based on aircraft and cloud radar co-observation conducted at Yitong,Jilin,Northeast China.The aircraft provided in situ measurements of cloud droplet size distribution,while the millimeter-wavelength cloud radar vertically scanned the same cloud that the aircraft penetrated.The reflectivity factor calculated from aircraft measurements was compared in detail with simultaneous radar observations.The results showed that the two reflectivities were comparable in warm clouds,but in ice cloud there were more differences,which were probably associated with the occurrence of liquid water.The acceptable agreement between reflectivities obtained in water cloud confirmed that it is feasible to derive cloud properties by using aircraft data,and hence for cloud radar to remotely sense cloud properties.Based on the dataset collected in warm clouds,the threshold of reflectivity to diagnose drizzle and cloud particles was studied by analyses of the probability distribution function of reflectivity from cloud particles and drizzle drops.The relationship between reflectivity factor (Z) and cloud liquid water content (LWC) was also derived from data on both cloud particles and drizzle.In comparison with cloud droplets,the relationship for drizzle was blurred by many scatter points and thus was less evident.However,these scatters could be partly removed by filtering out the drop size distribution with a large ratio of reflectivity and large extinction coefficient but small effective radius.Empirical relationships of Z-LWC for both cloud particles and drizzle could then be derived.

  6. IAEA's Safeguards and space-based radar

    International Nuclear Information System (INIS)

    The importance of non-proliferation of nuclear weapons can not be overemphasised. International Atomic Energy Agency (IAEA) has some involvement with each of several multilateral agreements currently in force, under its safeguards regime. It is, therefore, clear that every effort should be undertaken to make these measures effective. An important prerequisite for this is an efficient verification system. Although observation satellites were shown to be an important verification technique, most of them are part of a State's defence system and, therefore, not generally available. Data from commercial remote sensing satellites are improving. Also a number of countries are now orbiting such remote sensing satellites and others have plans to orbit sensors on board satellites with even higher resolutions. Moreover, the potential use of such satellites for enhancing the Agency's safeguards procedures has been demonstrated. Thus, it is natural that the applications of such satellites are exploited to the fullest. It is suggested that this technique could also contribute to the Agency's safeguards procedures. It is clear from the above test that radar imagery on its own may not be sufficient for a complete understanding of the activities taking place at a particular facility. Such data need to be combined with optical information for a complete interpretation. The study also shows that it is useful to carry out principal components analysis when using multispectral images. It is particularly useful when the scene contains vegetation because the principal components analysis (PCA) is a spectral enhancement tool. Combining the SAR and optical data, the technique could become a very useful tool for the IAEA. For the future, discussions on the Fissile Materials Cut Off Agreement are taking place in the Conference on Disarmament in Geneva. When this comes into force, commercial satellites may also play an important role in its verification procedures. Clearly in addition to the

  7. Radar Based Flow and Water Level Forecasting in Sewer Systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Rasmussen, Michael R.; Grum, M.;

    2009-01-01

    This paper describes the first radar based forecast of flow and/or water level in sewer systems in Denmark. The rainfall is successfully forecasted with a lead time of 1-2 hours, and flow/levels are forecasted an additional ½-1½ hours using models describing the behaviour of the sewer system. Both...... radar data and flow/water level model are continuously updated using online rain gauges and online in-sewer measurements, in order to make the best possible predictions. The project show very promising results, and show large potentials, exploiting the existing water infrastructure in future climate...

  8. Novel radar dwell scheduling algorithm based on pulse interleaving

    Institute of Scientific and Technical Information of China (English)

    Cheng Ting; He Zishu; Tang Ting

    2009-01-01

    The problem of scheduling radar dwells in multifunction phased array radar systems is addressed. A novel dwell scheduling algorithm is proposed. The whole scheduling process is based on an online pulse interleaving technique. It takes the system timing and energy constraints into acoount. In order to adapt the dynamic task load, the algorithm considers both the priorities and deadlines of tasks. The simulation results demonstrate that compared with the conventional adaptive dwell scheduling algorithm, the proposed one can improve the task drop rate and system resource utiliW effectively.

  9. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    OpenAIRE

    Xianjun Huang; Zhirun Hu; Peiguo Liu

    2014-01-01

    This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider t...

  10. Space-Based Tethered Array Radar (STAR) - A Distributed Small Satellite Network

    OpenAIRE

    Tomlinson, Philip; Brown, Thomas; Chakraborty, Dayamoy

    1988-01-01

    The Space-Based Tethered Array Radar (STAR) concept evolved from the DoD need for an affordable, launchable, survivable, and expandable Space-Based Radar for wide-area surveillance of airborne targets and for ballistic missile defense applications. Because low-observable threats can undermine conventional large monolithic Space-Based Radar satellite designs by forcing power-aperture products (inversely proportional to target radar cross-section) so high that the resulting heavy and expensive ...

  11. Quality-based generation of weather radar Cartesian products

    OpenAIRE

    K. Ośródka; J. Szturc

    2015-01-01

    Weather radar data volumes are commonly processed to obtain various 2-D Cartesian products based on the transfer from polar to Cartesian representations through a certain interpolation method. In this research an algorithm of the spatial interpolation of polar reflectivity data employing quality index data is applied to find the Cartesian reflectivity as plan position indicator products. On this basis, quality-based versions of standard algorithms for the generation of the foll...

  12. A utilização das imagens de radar meteorológico em Climatologia

    OpenAIRE

    Fragoso, Marcelo

    2012-01-01

    WEATHER RADAR IMAGE IN CLIMATOLOGY - After a brief overview about weather radar as a remote sensing instrument, some problems concerning the use of radar images are discussed. The great interest of radar images as a tool in Climatology is pointed out. Finally, a case study about two rainfall events in Nancy (France) in April 1995 is presented.

  13. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    International Nuclear Information System (INIS)

    This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications

  14. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    Directory of Open Access Journals (Sweden)

    Xianjun Huang

    2014-11-01

    Full Text Available This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS reduction applications.

  15. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xianjun, E-mail: xianjun.huang@manchester.ac.uk [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Hu, Zhirun [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Liu, Peiguo [College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-11-15

    This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.

  16. An algorithm for UWB radar-based human detection

    OpenAIRE

    Chang, SangHyun; Mitsumoto, Naoki; Burdick, Joel W.

    2009-01-01

    This paper presents an algorithm for human presence detection in urban environments using an ultra-wide-band (UWB) impulse-based mono-static radar. A specular multi-path model (SMPM) is used to characterize human body scattered UWB waveforms. The SMPM parameters are used within a classical likelihood ratio detector framework to detect the presence of humans via gait, with the aid of a multi-target tracking technique (MTT). Experimental results on a simple human gait detec...

  17. Radar target recognition based on micro-Doppler effect

    Institute of Scientific and Technical Information of China (English)

    DONG Wei-guang; LI Yan-jun

    2008-01-01

    Mechanical vibration of target structures will modulate the phase function of radar backscattering, and will induce thefrequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequencyshift, which is helpful for target recognition. Based on this.a micro-Doppler atomic storehouse is built for the targetrecognition, and four kinds of common classifiers are used separately to perform the classified recognition. The simulationexperimental results show that this method has high recognition rate above 90%.

  18. Mapping of the environment with a high resolution ground-based radar imager

    OpenAIRE

    Rouveure, R.; Monod, M.O.; Faure, P.

    2008-01-01

    The aim of this paper is to present the potential of microwave radar as a high resolution ground-based imager, in order to build radar maps in environmental applications. A new radar sensor named K2Pi, based on the principle of Frequency-Modulated Continuous Wave (FM-CW) is described. In order to build the radar maps, the R-SLAM algorithm has been developed. It is based on Simultaneous Localization And Mapping (SLAM) principles. The global radar map is constructed through a data merging proce...

  19. Mobile Ground-Based Radar Sensor for Localization and Mapping: An Evaluation of two Approaches

    OpenAIRE

    Damien Vivet; Franck Gérossier; Paul Checchin; Laurent Trassoudaine; Roland Chapuis

    2013-01-01

    This paper is concerned with robotic applications using a ground‐based radar sensor for simultaneous localization and mapping problems. In mobile robotics, radar technology is interesting because of its long range and the robustness of radar waves to atmospheric conditions, making these sensors well‐suited for extended outdoor robotic applications. Two localization and mapping approaches using data obtained from a 360° field of view microwave radar sensor are presented and compared. The first...

  20. Mimo radar waveform design for spectrum sharing with cellular systems a Matlab based approach

    CERN Document Server

    Khawar, Awais; Clancy, T Charles

    2016-01-01

    This book discusses spectrum sharing between cellular systems and radars. The book addresses a novel way to design radar waveforms that can enable spectrum sharing between radars and communication systems, without causing interference to communication systems, and at the same time achieving radar objectives of target detection, estimation, and tracking. The book includes a MATLAB-based approach, which provides reader with a way to learn, experiment, compare, and build on top of existing algorithms.

  1. New Precision Guidance Method Based on Bistatic Synthetic Apterture Radar

    Institute of Scientific and Technical Information of China (English)

    YANG Chun; ZENG Tao

    2008-01-01

    A new method is presented to improve guidance precision.This method is based on histatic synthetic aperture radar.The illuminator works in side looking mode,providing the synthetic aperture and the receiver is disposed on the seeker which operates in the forward looking mode.The receiving antenna is composed of four sub-antennas and so four synthetic aperture radar(SAR)images are to be generated.Target is positioned in SAR images by image matching.The bearing and elevation of image element of target are measured by the principle of monopulse angular measurement.Theory of the proposed method is derived and simulation on bearing measurement is done.Simulation shows that the method is valid and if SNR of target's image is above 30 dB.the angular measuring difference is witbin the confines of 0.04 degree.

  2. 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.

  3. Expert Knowledge Base to Support Maintenance of a Radar System

    OpenAIRE

    Stanislaw Duer

    2010-01-01

    This paper presents the method for the creation of an expert knowledge base of a military object, for example a radar system. Such a knowldge base can be widely used to support the process of the maintenance of a complex technical object. The first step is a maintenance evaluation of the object. During this kind of analysis, it is necessary to perform the grouping and classification of the functional elements of the object.It is realised using the functional scheme of the object presented. Fu...

  4. Detection of Multiple Unresolved Targets Based on Complex Indicated Angle Difference Using Multistatic Radar

    Directory of Open Access Journals (Sweden)

    Min Tao

    2014-08-01

    Full Text Available The detection of multiple unresolved targets is critical in radar technology. To precisely detect multiple unresolved targets is a prerequisite and the basis of all other processes. For monostatic radar, the detection method of multiple unresolved targets based on the complex indicated angle difference technique is first analyzed and then extended to multistatic radar. The detector of multiple unresolved targets is designed and simulation tests are presented under several scenarios. Moreover, the effect on detection performance of SNR, sensor number, and the geometrical configuration of targets and sensors are analyzed. The results show that with the same SNR, the multistatic radar detector performs better than the monostatic radar detector.

  5. NOAA Next Generation Radar (NEXRAD) Level II Base Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of Level II weather radar data collected from Next-Generation Radar (NEXRAD) stations located in the contiguous United States, Alaska, Hawaii,...

  6. Space-based millimeter-wave debris tracking radar

    Science.gov (United States)

    Chang, Kai; Pollock, Michael A.; Skrehot, Michael K.

    1991-01-01

    NORAD system currently tracks and predicts orbits of space objects of 80 mm or larger in diameter. The small debris of less than 80 mm, traveling at high speed, could cause damage to Space Station or space vehicles. To overcome this problem, a 35 GHz space-based millimeter-wave radar system is proposed to track the particles ranging in size from 4 mm to 80 mm up to a range of 25 Km. The system requires a large phased array which should be developed in monolithic circuits for cost reduction.

  7. On the use of radar-based quantitative precipitation estimates for precipitation frequency analysis

    Science.gov (United States)

    Eldardiry, Hisham; Habib, Emad; Zhang, Yu

    2015-12-01

    The high spatio-temporal resolutions of radar-based multi-sensor Quantitative Precipitation Estimates (QPEs) makes them a potential complement to the gauge records for engineering design purposes, such as precipitation frequency analysis. The current study investigates three fundamental issues that arise when radar-based QPE products are used in frequency analysis: (a) Effect of sample size due to the typically short records of radar products; (b) Effect of uncertainties present in radar-rainfall estimation algorithms; and (c) Effect of the frequency estimation approach adopted. The study uses a 13-year dataset of hourly, 4 × 4 km2 radar-based over a domain that covers Louisiana, USA. Data-based investigations, as well as synthetic simulations, are performed to quantify the uncertainties associated with the radar-based derived frequencies, and to gain insight into the relative contributions of short record lengths and those from conditional biases in the radar product. Three regional estimation procedures were tested and the results indicate the sensitivity of the radar frequency estimates to the selection of the estimation approach and the impact on the uncertainties of the derived extreme quantiles. The simulation experiments revealed that the relatively short radar records explained the majority of the uncertainty associated with the radar-based quantiles; however, they did not account for any tangible contribution to the systematic underestimation observed between radar- and gauge-based frequency estimates. This underestimation was mostly attributable to the conditional bias inherent in the radar product. Addressing such key outstanding problems in radar-rainfall products is necessary before they can be fully and reliably used for frequency analysis applications.

  8. Separation of Doppler radar-based respiratory signatures.

    Science.gov (United States)

    Lee, Yee Siong; Pathirana, Pubudu N; Evans, Robin J; Steinfort, Christopher L

    2016-08-01

    Respiration detection using microwave Doppler radar has attracted significant interest primarily due to its unobtrusive form of measurement. With less preparation in comparison with attaching physical sensors on the body or wearing special clothing, Doppler radar for respiration detection and monitoring is particularly useful for long-term monitoring applications such as sleep studies (i.e. sleep apnoea, SIDS). However, motion artefacts and interference from multiple sources limit the widespread use and the scope of potential applications of this technique. Utilising the recent advances in independent component analysis (ICA) and multiple antenna configuration schemes, this work investigates the feasibility of decomposing respiratory signatures into each subject from the Doppler-based measurements. Experimental results demonstrated that FastICA is capable of separating two distinct respiratory signatures from two subjects adjacent to each other even in the presence of apnoea. In each test scenario, the separated respiratory patterns correlate closely to the reference respiration strap readings. The effectiveness of FastICA in dealing with the mixed Doppler radar respiration signals confirms its applicability in healthcare applications, especially in long-term home-based monitoring as it usually involves at least two people in the same environment (i.e. two people sleeping next to each other). Further, the use of FastICA to separate involuntary movements such as the arm swing from the respiratory signatures of a single subject was explored in a multiple antenna environment. The separated respiratory signal indeed demonstrated a high correlation with the measurements made by a respiratory strap used currently in clinical settings. PMID:26358241

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  11. Research on Atmospheric Disturbance Correction method of ground-based radar interferometry

    International Nuclear Information System (INIS)

    The high-frequency signal is often used as the communication signal of Ground-based radar, which is susceptible to atmospheric effects. An atmospheric disturbance correction of radar signal is required to obtain the monitoring accuracy of better than millimeter in precision deformation monitoring using ground-based radar interferometry. In this paper, we analyzed the experimental-data change of ground-based radar in the atmospheric disturbance statistically and proposed a correction method based on the discrete stable point in the global environment. The following experiment proved that this method can optimize the measurement results for the scene of small-scale

  12. Silicon-photonics-based wideband radar beamforming: basic design

    Science.gov (United States)

    Fathpour, Sasan

    2010-01-01

    Proposed is silicon-photonics-based phased array antenna beamforming for high-resolution long-range radars with wide instantaneous radio frequency (rf) bandwidth. Specifically, the proposed silicon-photonics beamformer platform offers the potential for cost-effective monolithic chip-scale integration of photonic delay lines, 2×2 optical switches, variable optical attenuators, and optical amplifiers that form the base unit of a rf transmit/receive array signal processor. In effect, the proposed silicon-photonics devices empower the design of a powerful proposed photonic beamformer with one time-delay unit per antenna element. Device-level designs studies are shown that promise meeting the high-resolution radar mission-critical requirements via time delays of up to 2.5 ns, switching times of less than 100 ns, optical isolations as good as 50 dB, and optical gains of up to 6 dB. Longer delays are achieved off chip using optical fibers.

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

    Science.gov (United States)

    Fritz, Jason P.

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

  14. A radar-based sensor network for bridge displacement measurements

    Science.gov (United States)

    Rice, Jennifer A.; Gu, Changzhan; Li, Changzhi; Guan, Shanyue

    2012-04-01

    The development of effective structural health monitoring (SHM) strategies is critical as aging infrastructure remains a national concern with widespread impact on the quality of our daily lives. Wireless smart sensor networks (WSSNs) are an attractive alternative to traditional SHM systems for their lower deployment cost and their ability to enable new methods of distributed data processing. While acceleration has been the primary measurement utilized in most WSSN SHM applications, practically and accurately capturing structural deflections has been proven much more challenging. Displacement sensors produce reliable low-frequency measurements but are often difficult to implement in long-term field deployments. Conventional technologies for measuring deflection, both dynamic and static, are either too bulky or expensive to be integrated into WSSNs or lack sufficient accuracy. This paper presents the validation and characterization of a network of low-cost, wireless radar-based sensors for the enhancement of low-frequency vibrationbased bridge monitoring and the measurement of static bridge deflections. Experimental results utilizing a laboratoryscale truss bridge are presented and the performance of the wireless radar sensors is compared to conventional vibration and displacement transducers. In addition, challenges associated with detection distance, interference rejection and signal processing are discussed.

  15. Radar-Based Analysis of Convective Storms over Northwestern Italy

    Directory of Open Access Journals (Sweden)

    Paolo Davini

    2011-12-01

    Full Text Available Thunderstorms may cause large damages to infrastructures and population, therefore the possible identification of the areas with the highest occurrence of these events is especially relevant. Nevertheless, few extensive studies of these phenomena with high spatial and temporal resolution have been carried out in the Alps and none of them includes North-western Italy. To analyze thunderstorm events, the data of the meteorological radar network of the regional meteorological service of Piedmont region (ARPA Piemonte have been used in this work. The database analyzed includes all thunderstorms occurred during the warm months (April to September of a 6-year period (2005–2010. The tracks of each storm have been evaluated using a storm tracking algorithm. Several characteristics of the storms have been analyzed, such as the duration, the spatial and the temporaldistribution, the direction and the distance travelled. Obtained results revealed several important characteristics that may be useful for nowcasting purposes providing a first attempt of radar-based climatology in the considered region.

  16. A Human Gait Classification Method Based on Radar Doppler Spectrograms

    Directory of Open Access Journals (Sweden)

    Fok Hing Chi Tivive

    2010-01-01

    Full Text Available An image classification technique, which has recently been introduced for visual pattern recognition, is successfully applied for human gait classification based on radar Doppler signatures depicted in the time-frequency domain. The proposed method has three processing stages. The first two stages are designed to extract Doppler features that can effectively characterize human motion based on the nature of arm swings, and the third stage performs classification. Three types of arm motion are considered: free-arm swings, one-arm confined swings, and no-arm swings. The last two arm motions can be indicative of a human carrying objects or a person in stressed situations. The paper discusses the different steps of the proposed method for extracting distinctive Doppler features and demonstrates their contributions to the final and desirable classification rates.

  17. Radar-to-Radar Interference Suppression for Distributed Radar Sensor Networks

    OpenAIRE

    Wen-Qin Wang; Huaizong Shao

    2014-01-01

    Radar sensor networks, including bi- and multi-static radars, provide several operational advantages, like reduced vulnerability, good system flexibility and an increased radar cross-section. However, radar-to-radar interference suppression is a major problem in distributed radar sensor networks. In this paper, we present a cross-matched filtering-based radar-to-radar interference suppression algorithm. This algorithm first uses an iterative filtering algorithm to suppress the radar-to-radar ...

  18. Spatial based Expectation Maximizing (EM)

    OpenAIRE

    Balafar M A

    2011-01-01

    Abstract Background Expectation maximizing (EM) is one of the common approaches for image segmentation. Methods an improvement of the EM algorithm is proposed and its effectiveness for MRI brain image segmentation is investigated. In order to improve EM performance, the proposed algorithms incorporates neighbourhood information into the clustering process. At first, average image is obtained as neighbourhood information and then it is incorporated in clustering process. Also, as an option, us...

  19. Optimum Design for Coexistence Between Matrix Completion Based MIMO Radars and a MIMO Communication System

    OpenAIRE

    Li, Bo; Petropulu, Athina P.; Trappe, Wade

    2015-01-01

    Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data that need to be forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between a MIMO-MC radar and a communication system, so that the latter interferes minimally with the former. First, the communication system transmit covariance matrix...

  20. FPGA Based RADAR Signal Emulator for Signal Processing Test Applications

    OpenAIRE

    S. Yoganand; S. Sundara Babu

    2014-01-01

    The RADARs use complex techniques such as stagger PRI, jitter PRI with frequency agile characteristics. The frequency agile RADARs switch frequencies with in a pulse to get different types of advantages. Today lot of RADAR signal processing takes place on FPGA platform. These signal processing algorithms include pulse parameters estimation, deinterleaving of mixed pulse patterns, processing complex chirp signals etc. All these algorithms need to be tested at various levels bef...

  1. Road and Obstacle Detection Based on Multi-layer Laser Radar in Driverless Car

    OpenAIRE

    Duan, Jianmin; ZHENG Kaihua; SHI Lixiao

    2015-01-01

    To make a driverless car with better environment awareness, multi-layer laser radar was applied to detect roads and obstacles. Firstly the road edge data set was extracted from numerous laser radar data based on characteristics of the road edge data, and the cluster analysis of the data sets was done with the improved COBWEB algorithm based on Euclidean distance.

  2. The radar signal simulation based on the analysis of Pulse-Doppler radar for digital signal processing implementation in the Matlab environment

    Directory of Open Access Journals (Sweden)

    Yu. Yu. Reutskaya

    2015-03-01

    Full Text Available Introduction. The complexity of modern radar (RLS due to their versatility and the need to adapt to the interference situation is constantly changed. The models to test the basic ideas to be implemented in the radar are required. It is important to consider the main stages of the simulation of the radar signal based on the analysis of radar operation. Problem statement. The creation of a universal analytical model to build a radar signal in Matlab is considered. Theoretical results. Stages and results of the radar signal simulation are presented and based on the analysis of pulse – Doppler radar. Basic analytical relations ofthe task are given. Features of simulation when signals of additive fluctuation noise and clutter together with the echo target signals arrive are considered. Conclusion. As a result of analysis of radar interference conditions on the basis of existing relations an optimum variant model of radar signal in Matlab environment is reached. This is the basis for further evaluation of the digital processing effectiveness of the radar signal to background noise and interference (clutter, namely to determine the distance to targets and target’s speeds. . The main advantages of the Mellin transform using for recognizing signals at different scales are presented is conclusions.

  3. Planetary Geology with Imaging Radar: Insights from Earth-based Lunar Studies, 2001–2015

    Science.gov (United States)

    Campbell, Bruce A.

    2016-06-01

    Radar exploration of the Solar System changed dramatically during and beyond the period of the Magellan mission to Venus. These changes included an expansion of the community familiar with microwave data, and the forging of a strong connection with polarimetric scattering models developed through terrestrial field measurements and airborne radar studies. During the period, advances in computing power and imaging techniques also allowed Earth-based radar experiments to acquire data at the highest spatial resolutions permitted by their transmitter systems. This paper traces these developments through a case study of lunar observations over the past 15 years, and their implications for ongoing and future Solar System radar studies.

  4. 5 year radar-based rainfall statistics: disturbances analysis and development of a post-correction scheme for the German radar composite

    Directory of Open Access Journals (Sweden)

    A. Wagner

    2015-02-01

    Full Text Available A radar-based rainfall statistic demands high quality data that provide realistic precipitation amounts in space and time. Instead of correcting single radar images, we developed a post-correction scheme for long-term composite radar data that corrects corrupted areas, but preserves the original precipitation patterns. The post-correction scheme is based on a 5 year statistical analysis of radar composite data and its constituents. The accumulation of radar images reveals artificial effects that are not visible in the individual radar images. Some of them are already inherent to single radar data such as the effect of increasing beam height, beam blockage or clutter remnants. More artificial effects are introduced in the process of compositing such as sharp gradients at the boundaries of overlapping areas due to different beam heights and resolution. The cause of these disturbances, their behaviour with respect to reflectivity level, season or altitude is analysed based on time-series of two radar products: the single radar reflectivity product PX for each of the 16 radar systems of the German Meteorological Service (DWD for the time span 2000 to 2006 and the radar composite product RX of DWD from 2005 through to 2009. These statistics result in additional quality information on radar data that is not available elsewhere. The resulting robust characteristics of disturbances, e.g. the dependency of the frequencies of occurrence of radar reflectivities on beam height, are then used as a basis for the post-correction algorithm. The scheme comprises corrections for shading effects and speckles, such as clutter remnants or overfiltering, as well as for systematic differences in frequencies of occurrence of radar reflectivities between the near and the far ranges of individual radar sites. An adjustment to rain gauges is also included. Applying this correction, the Root-Mean-Square-Error for the comparison of radar derived annual rain amounts with

  5. 5 year radar-based rainfall statistics: disturbances analysis and development of a post-correction scheme for the German radar composite

    Science.gov (United States)

    Wagner, A.; Seltmann, J.; Kunstmann, H.

    2015-02-01

    A radar-based rainfall statistic demands high quality data that provide realistic precipitation amounts in space and time. Instead of correcting single radar images, we developed a post-correction scheme for long-term composite radar data that corrects corrupted areas, but preserves the original precipitation patterns. The post-correction scheme is based on a 5 year statistical analysis of radar composite data and its constituents. The accumulation of radar images reveals artificial effects that are not visible in the individual radar images. Some of them are already inherent to single radar data such as the effect of increasing beam height, beam blockage or clutter remnants. More artificial effects are introduced in the process of compositing such as sharp gradients at the boundaries of overlapping areas due to different beam heights and resolution. The cause of these disturbances, their behaviour with respect to reflectivity level, season or altitude is analysed based on time-series of two radar products: the single radar reflectivity product PX for each of the 16 radar systems of the German Meteorological Service (DWD) for the time span 2000 to 2006 and the radar composite product RX of DWD from 2005 through to 2009. These statistics result in additional quality information on radar data that is not available elsewhere. The resulting robust characteristics of disturbances, e.g. the dependency of the frequencies of occurrence of radar reflectivities on beam height, are then used as a basis for the post-correction algorithm. The scheme comprises corrections for shading effects and speckles, such as clutter remnants or overfiltering, as well as for systematic differences in frequencies of occurrence of radar reflectivities between the near and the far ranges of individual radar sites. An adjustment to rain gauges is also included. Applying this correction, the Root-Mean-Square-Error for the comparison of radar derived annual rain amounts with rain gauge data

  6. A digital beamforming processor for the joint DoD/NASA space based radar mission

    Science.gov (United States)

    Fischman, Mark A.; Le, Charles; Rosen, Paul A.

    2004-01-01

    The Space Based Radar (SBR) program includes a joint technology demonstration between NASA and the Air Force to design a low-earth orbiting, 2x50 m L-band radar system for both Earth science and intelligence related observations.

  7. On reconciling ground-based with spaceborne normalized radar cross section measurements

    DEFF Research Database (Denmark)

    Baumgartner, Francois; Munk, Jens; Jezek, K C;

    2002-01-01

    This study examines differences in the normalized radar cross section, derived from ground-based versus spaceborne radar data. A simple homogeneous half-space model, indicates that agreement between the two improves as 1) the distance from the scatterer is increased; and/or 2) the extinction...

  8. Radar equations for modern radar

    CERN Document Server

    Barton, David K

    2012-01-01

    Based on the classic Radar Range-Performance Analysis from 1980, this practical volume extends that work to ensure applicability of radar equations to the design and analysis of modern radars. This unique book helps you identify what information on the radar and its environment is needed to predict detection range. Moreover, it provides equations and data to improve the accuracy of range calculations. You find detailed information on propagation effects, methods of range calculation in environments that include clutter, jamming and thermal noise, as well as loss factors that reduce radar perfo

  9. Radar cross-section reduction based on an iterative fast Fourier transform optimized metasurface

    Science.gov (United States)

    Song, Yi-Chuan; Ding, Jun; Guo, Chen-Jiang; Ren, Yu-Hui; Zhang, Jia-Kai

    2016-07-01

    A novel polarization insensitive metasurface with over 25 dB monostatic radar cross-section (RCS) reduction is introduced. The proposed metasurface is comprised of carefully arranged unit cells with spatially varied dimension, which enables approximate uniform diffusion of incoming electromagnetic (EM) energy and reduces the threat from bistatic radar system. An iterative fast Fourier transform (FFT) method for conventional antenna array pattern synthesis is innovatively applied to find the best unit cell geometry parameter arrangement. Finally, a metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full wave simulation software Ansys HFSSTM and marvelous agreement is observed.

  10. Correlating Flight Behavior and Radar Measurements for Species Based Classification of Bird Radar Echoes for Wind Energy Site Assessment

    Science.gov (United States)

    Werth, S. P.; Frasier, S. J.

    2015-12-01

    Wind energy is one of the fastest-growing segments of the world energy market, offering a clean and abundant source of electricity. However, wind energy facilities can have detrimental effects on wildlife, especially birds and bats. Monitoring systems based on marine navigation radar are often used to quantify migration near potential wind sites, but the ability to reliably distinguish between bats and different varieties of birds has not been practically achieved. This classification capability would enable wind site selection that protects more vulnerable species, such as bats and raptors. Flight behavior, such as wing beat frequency, changes in speed, or changes in orientation, are known to vary by species [1]. The ability to extract these properties from radar data could ultimately enable a species based classification scheme. In this work, we analyze the relationship between radar measurements and bird flight behavior in echoes from avifauna. During the 2014 fall migration season, the UMass dual polarized weather radar was used to collect low elevation observations of migrating birds as they traversed through a fixed antenna beam. The radar was run during the night time, in clear-air conditions. Data was coherently integrated, and detections of biological targets exceeding an SNR threshold were extracted. Detections without some dominant frequency content (i.e. clear periodicity, potentially the wing beat frequency) were removed from the sample in order to isolate observations suspected to contain a single species or bird. For the remaining detections, measurements including the polarimetric products and the Doppler spectrum were extracted at each time step over the duration of the observation. The periodic and time changing nature of some of these different measurements was found to have a strong correlation with flight behavior (i.e. flapping vs. gliding behavior). Assumptions about flight behavior and orientation were corroborated through scattering

  11. Expert Knowledge Base to Support Maintenance of a Radar System

    Directory of Open Access Journals (Sweden)

    Stanislaw Duer

    2010-08-01

    Full Text Available This paper presents the method for the creation of an expert knowledge base of a military object, for example a radar system. Such a knowldge base can be widely used to support the process of the maintenance of a complex technical object. The first step is a maintenance evaluation of the object. During this kind of analysis, it is necessary to perform the grouping and classification of the functional elements of the object.It is realised using the functional scheme of the object presented. Further, diagnostic information is combined with specialised experts' knowledge and transformed it into a set of servicing information. The participation of experts in the process of expert knowledge base preparation is significant. The purpose is to capture information that will be a fundamental for the design of a maintenance system dedicated to the particulartechnical object. The methods proposed were verified with appropriate examples, in which the set of specialised diagnostic information of the object was determined.Defence Science Journal, 2010, 60(5, pp.531-540, DOI:http://dx.doi.org/10.14429/dsj.60.84

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

    Science.gov (United States)

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

    2016-04-01

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

  13. Photoelectric radar servo control system based on ARM+FPGA

    Science.gov (United States)

    Wu, Kaixuan; Zhang, Yue; Li, Yeqiu; Dai, Qin; Yao, Jun

    2016-01-01

    In order to get smaller, faster, and more responsive requirements of the photoelectric radar servo control system. We propose a set of core ARM + FPGA architecture servo controller. Parallel processing capability of FPGA to be used for the encoder feedback data, PWM carrier modulation, A, B code decoding processing and so on; Utilizing the advantage of imaging design in ARM Embedded systems achieves high-speed implementation of the PID algorithm. After the actual experiment, the closed-loop speed of response of the system cycles up to 2000 times/s, in the case of excellent precision turntable shaft, using a PID algorithm to achieve the servo position control with the accuracy of + -1 encoder input code. Firstly, This article carry on in-depth study of the embedded servo control system hardware to determine the ARM and FPGA chip as the main chip with systems based on a pre-measured target required to achieve performance requirements, this article based on ARM chip used Samsung S3C2440 chip of ARM7 architecture , the FPGA chip is chosen xilinx's XC3S400 . ARM and FPGA communicate by using SPI bus, the advantage of using SPI bus is saving a lot of pins for easy system upgrades required thereafter. The system gets the speed datas through the photoelectric-encoder that transports the datas to the FPGA, Then the system transmits the datas through the FPGA to ARM, transforms speed datas into the corresponding position and velocity data in a timely manner, prepares the corresponding PWM wave to control motor rotation by making comparison between the position data and the velocity data setted in advance . According to the system requirements to draw the schematics of the photoelectric radar servo control system and PCB board to produce specially. Secondly, using PID algorithm to control the servo system, the datas of speed obtained from photoelectric-encoder is calculated position data and speed data via high-speed digital PID algorithm and coordinate models. Finally, a

  14. Investigation on Multimode SAR Imaging Based on Digital Array Radar

    OpenAIRE

    Li Xue-shi; Sun Guang-cai; Shao Peng; Wu Yu-feng; Xing Meng-dao

    2014-01-01

    Digital Array Radar (DAR) has the ability of simultaneous multimode imaging and has many potential applications. This paper firstly introduces the basic hardware structure and the operation principle of DAR. Combined with the Digital BeamForming (DBF) technique, six operational modes that can be used in multimode Synthetic Aperture Radar (SAR) imaging are proposed, and the corresponding novel imaging modes are produced. Moreover, the design of the novel imaging modes is introduced in detail. ...

  15. Ultrawideband imaging radar based on OFDM: system simulation analysis

    Science.gov (United States)

    Garmatyuk, Dmitriy

    2006-05-01

    Orthogonal frequency division-multiplexing (OFDM) is rapidly emerging as a preferred method of UWB signaling in commercial applications aimed mainly at low-power, high data-rate communications. This paper explores the possibility of applying OFDM to use in imaging radar technology. Ultra-wideband nature of the signal provides for high resolution of the radar, whereas usage of multi-sub-carrier method of modulation allows for dynamic spectrum allocation. Robust multi-path performance of OFDM signals and heavy reliance of transceiver design on digital processors easily implemented in modern VLSI technology make a number of possible applications viable, e.g.: portable high-resolution indoor radar/movement monitoring system; through-the-wall/foliage synthetic aperture imaging radar with a capability of image transmission/broadcasting, etc. Our work is aimed to provide a proof-of-concept simulation scenario to explore numerous aspects of UWB-OFDM radar imaging through evaluating range and cross-range imaging performance of such a system with an eventual goal of software-defined radio (SDR) implementation. Stripmap SAR topology was chosen for modeling purposes. Range/cross-range profiles were obtained along with full 2-D images for multi-target in noise scenarios. Model set-up and results of UWB-OFDM radar imaging simulation study using Matlab/Simulink modeling are presented and discussed in this paper.

  16. Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

    Institute of Scientific and Technical Information of China (English)

    Huang Hao; Pan Minghai; Lu Zhijun

    2015-01-01

    Hardware-in-the-loop (HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting sig-nal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory (DRFM) system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile (HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

  17. Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

    Directory of Open Access Journals (Sweden)

    Huang Hao

    2015-10-01

    Full Text Available Hardware-in-the-loop (HWIL simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory (DRFM system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile (HRRP are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

  18. Robust Radar Emitter Recognition Based on the Three-Dimensional Distribution Feature and Transfer Learning.

    Science.gov (United States)

    Yang, Zhutian; Qiu, Wei; Sun, Hongjian; Nallanathan, Arumugam

    2016-01-01

    Due to the increasing complexity of electromagnetic signals, there exists a significant challenge for radar emitter signal recognition. To address this challenge, multi-component radar emitter recognition under a complicated noise environment is studied in this paper. A novel radar emitter recognition approach based on the three-dimensional distribution feature and transfer learning is proposed. The cubic feature for the time-frequency-energy distribution is proposed to describe the intra-pulse modulation information of radar emitters. Furthermore, the feature is reconstructed by using transfer learning in order to obtain the robust feature against signal noise rate (SNR) variation. Last, but not the least, the relevance vector machine is used to classify radar emitter signals. Simulations demonstrate that the approach proposed in this paper has better performances in accuracy and robustness than existing approaches. PMID:26927111

  19. Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations

    Science.gov (United States)

    Bolen, Steven M.; Chandrasekar, V.

    2003-06-01

    The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ≥ 0.5°/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

  20. An Energy Consumption Optimized Clustering Algorithm for Radar Sensor Networks Based on an Ant Colony Algorithm

    OpenAIRE

    Ting Jiang; Wei Zang; Chenglin Zhao; Jiong Shi

    2010-01-01

    We optimize the cluster structure to solve problems such as the uneven energy consumption of the radar sensor nodes and random cluster head selection in the traditional clustering routing algorithm. According to the defined cost function for clusters, we present the clustering algorithm which is based on radio-free space path loss. In addition, we propose the energy and distance pheromones based on the residual energy and aggregation of the radar sensor nodes. According to bionic heuristic a...

  1. LPI radar signal detection based on radial integration of Choi-Williams time-frequency image

    Institute of Scientific and Technical Information of China (English)

    Yongjian Liu; Peng Xiao; Hongchao Wu; Weihua Xiao

    2015-01-01

    This paper mainly revolves the time-frequency image of low probability of intercept (LPI) radar signals and carries out research work on image features selection and extraction and recognition. Since Choi-Wil iams distribution (CWD) uses the ex-ponential kernel of bilinear generalized class of time-frequency distribution, it has an excel ent time-frequency aggregation. And it is suitable for detecting LPI radar signals in a low signal-to-noise ratio (SNR) condition. A radial integration method based on the in-tegral rotating factor is proposed to detect LPI radar signals when the signals’ time-frequency image is obtained. First, the digital image processing method is used to preprocess the LPI radar sig-nals’ time-frequency images after CWD transformation; then, the radial integration method based on the integral rotating factor is used to detect LPI radar signals in the binary images. The analytic results of real data show that the method has a good performance on detecting LPI radar signals in a low SNR condition. Additional y, the method is simple and takes less logic resources and has the potential of real-time detection of LPI radar signals.

  2. Doppler weather Radar based Nowcasting of cyclone Ogni

    Indian Academy of Sciences (India)

    Soma Sen Roy; V Lakshmanan; S K Roy Bhowmik; S B Thampi

    2010-04-01

    In this paper, we describe offline analysis of Indian Doppler Weather Radar (DWR) data from cyclone Ogni using a suite of radar algorithms as implemented on NEXRAD and the advanced algorithms developed jointly by the National Severe Storms Laboratory (NSSL) and the University of Oklahoma. We demonstrate the applicability of the various algorithms to Indian radar data, the improvement in the quality control and evaluate the benefit of nowcasting capabilities in Indian conditions. New information about the tropical cyclone structure, as derived from application of the algorithms is also discussed in this study. Finally, we suggest improvements that could be made to the Indian data collection strategies, networking and real-time analysis. Since this is the first study of its kind to process and utilize DWR data in a tropical climate, the suggestions on real-time analysis and data collection strategies made in this paper, would in many cases, be beneficial to other countries embarking on DWR network modernization programs.

  3. An Energy Consumption Optimized Clustering Algorithm for Radar Sensor Networks Based on an Ant Colony Algorithm

    Directory of Open Access Journals (Sweden)

    Jiang Ting

    2010-01-01

    Full Text Available We optimize the cluster structure to solve problems such as the uneven energy consumption of the radar sensor nodes and random cluster head selection in the traditional clustering routing algorithm. According to the defined cost function for clusters, we present the clustering algorithm which is based on radio-free space path loss. In addition, we propose the energy and distance pheromones based on the residual energy and aggregation of the radar sensor nodes. According to bionic heuristic algorithm, a new ant colony-based clustering algorithm for radar sensor networks is also proposed. Simulation results show that this algorithm can get a better balance of the energy consumption and then remarkably prolong the lifetime of the radar sensor network.

  4. Investigation on Multimode SAR Imaging Based on Digital Array Radar

    Directory of Open Access Journals (Sweden)

    Li Xue-shi

    2014-08-01

    Full Text Available Digital Array Radar (DAR has the ability of simultaneous multimode imaging and has many potential applications. This paper firstly introduces the basic hardware structure and the operation principle of DAR. Combined with the Digital BeamForming (DBF technique, six operational modes that can be used in multimode Synthetic Aperture Radar (SAR imaging are proposed, and the corresponding novel imaging modes are produced. Moreover, the design of the novel imaging modes is introduced in detail. The simulation results confirm the efficiency and precision of the imaging modes.

  5. High resolution mapping of the environment with a gound-based radar imager

    OpenAIRE

    Rouveure, R.; Monod, M.O.; Faure, P.

    2009-01-01

    The aim of this paper is to show the potential of the microwave radar as a sensor dedicated to outdoor perception. A new radar sensor named K2PI, based on the principle of Frequency-Modulated Continuous Wave (FM-CW) is presented here. An application in simultaneous localization and mapping using scan matching of radar images (R-SLAM algorithm) has been developed and first results in different environments are presented. Trajectories obtained by the R-Slam algorithm are compared with GPS posit...

  6. 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

  7. Multistatic Wireless Fidelity Network Based Radar – Results of the Chrcynno Experiment

    Directory of Open Access Journals (Sweden)

    S. Rzewuski

    2014-04-01

    Full Text Available This paper presents the theory and experimental result of passive radar using WIFI transmitters as illuminators of opportunity. As a result of experiments conducted on 17th August 2013 at airfield Chrcynno a Cessna C208 airplane was detected and tracked using multistatic passive radar system based on low power signal from WIFI network nodes, which were acting as non cooperative illuminators of opportunity. In the experiment 3 wireless access points were communicating with each other and illuminating the radar scene (airfield. The direct reference and reflected (surveillance signals have been acquired and processed using specially developed algorithm presented in the paper. After signal processing using Passive Coherent Location methods target has been detected. This paper describes in details the algorithms and the results of the experiment for the multistatic passive radar based on the WIFI signal.

  8. A GIS-based disaggregate spatial watershed analysis using RADAR data

    International Nuclear Information System (INIS)

    Hydrology is the study of water in all its forms, origins, and destinations on the earth.This paper develops a novel modeling technique using a geographic information system (GIS) to facilitate watershed hydrological routing using RADAR data. The RADAR rainfall data, segmented to 4 km by 4 km blocks, divides the watershed into several sub basins which are modeled independently. A case study for the GIS-based disaggregate spatial watershed analysis using RADAR data is provided for South Fork Cowikee Creek near Batesville, Alabama. All the data necessary to complete the analysis is maintained in the ArcView GIS software. This paper concludes that the GIS-Based disaggregate spatial watershed analysis using RADAR data is a viable method to calculate hydrological routing for large watersheds. (author)

  9. A New Radar TBD Method Based on RD-CTS

    Institute of Scientific and Technical Information of China (English)

    MOLi; WUSiliang; MAOErke

    2005-01-01

    Track-before-detect (TBD) is a useful strategy for weak target detection that manages to integrate target energy along candidate trajectories and test whether the summation is large enough to declare a target. Several methods have been proposed to apply TBD in radar weak target detection, but none of them could make profitable use of the inherent characteristic of radar data. A simple and time saving radar TBD method is proposed, which is unique in an innovative Range-Doppler Candidate trajectories structure (RD-CTS). A number of candidate trajectories are hypothesized off-line, taking advantage of the correlation of the Doppler and range of each “root” image cell. Measurements along possible target trajectories are then integrated and a target is declared if the measurement sum, or merit function, exceeds a threshold. The CFAR (Constant false alarm rate) detection and false alarm probability determination are analyzed as well. Under a practical set of radar parameters, good detection performances are presented that at about 100% detection probability, 7.5dB SNR gain is achieved through 15-frame non-coherent integration.

  10. Hyper-parameter selection in non-quadratic regularization-based radar image formation

    OpenAIRE

    Batu, Özge; Batu, Ozge; Çetin, Müjdat; Cetin, Mujdat

    2008-01-01

    We consider the problem of automatic parameter selection in regularization-based radar image formation techniques. It has previously been shown that non-quadratic regularization produces feature-enhanced radar images; can yield superresolution; is robust to uncertain or limited data; and can generate enhanced images in non-conventional data collection scenarios such as sparse aperture imaging. However, this regularized imaging framework involves some hyper-parameters, whose choice...

  11. Simulation Analysis and Model of Current Retrieval Based on Marine Radar Sea Clutter Images

    OpenAIRE

    Liqiang Liu; Yuntao Dai; Jinyu Gao

    2014-01-01

    Using the sea clutter image from X-Band radar for current retrieval is an effective way of obtaining information on ocean currents. Traditional methods used for current retrieval have been based on the least squares algorithm, which is not only simple and efficient but also generally speaking accurate. In order to improve the precision of current retrieval, this paper has, as its goal, the study of the used radar connected with sea clutter imaging for current retrieval, with the particle swar...

  12. Detection-Discrimination Method for Multiple Repeater False Targets Based on Radar Polarization Echoes

    OpenAIRE

    ZONG, Z. W.; L. F. SHI; Y. Z. LI; X.S. Wang

    2014-01-01

    Multiple repeat false targets (RFTs), created by the digital radio frequency memory (DRFM) system of jammer, are widely used in practical to effectively exhaust the limited tracking and discrimination resource of defence radar. In this paper, common characteristic of radar polarization echoes of multiple RFTs is used for target recognition. Based on the echoes from two receiving polarization channels, the instantaneous polarization radio (IPR) is defined and its variance is derived by employi...

  13. Extended radar-based hail detection testing over the Czech territory

    Czech Academy of Sciences Publication Activity Database

    Skripniková, Kateřina; Kyznarová, H.; Novák, P.

    Amtsgericht München : European Severe Storms Laboratory e.V. (ESSL), 2015. ECSS2015-20-1. [European Conference on Severe Storms (ECSS) /8./. 14.09.2015–18.09.2015, Wiener Neustadt] Institutional support: RVO:68378289 Keywords : radar-based hail detection * Doppler weather radar * Waldvogel algorithm * NEXRAD hail detection algorithm Subject RIV: DG - Athmosphere Sciences, Meteorology http://meetingorganizer.copernicus.org/ECSS2015/ECSS2015-20-1.pdf

  14. Descoberta de conhecimentos em base de dados

    OpenAIRE

    Ramos, Célia M. Q.; Lobo, Fernando

    2003-01-01

    A sociedade actual é caracterizada por uma inundação de dados provenientes de diversas fontes, existentes numa vasta gama de áreas económicas, sociais, cientificas, etc. A análise dos dados, armazenados em Bases de Dados, é cada vez mais pertinente para garantir a competitividade e o sucesso das organizações. Este artigo apresenta a nova área de conhecimento “Descoberta de Conhecimento em Bases de Dados” que permite efectuar análises dos dados e extrair conhecimento útil e adequado para o ...

  15. Numerical simulation and inversion of offshore area depth based on x-band microwave radar

    Institute of Scientific and Technical Information of China (English)

    WANG Li; WU Xiongbin; PI Xiaoshan; MA Ketao; LIU Jianfei; TIAN Yun

    2015-01-01

    A detection method of offshore area depth utilizing the x-band microwave radar is proposed. The method is based on the sea clutter imaging mechanism of microwave radar, and combined with dispersion equation of the liner wave theorem and least square method (LSM), consequently get the inversion results of water depth in the detected region. The wave monitoring system OSMAR-X exploited by the Ocean State Laborato-ry, Wuhan University, based on a microwave radar has proven to be a powerful tool to monitor ocean waves in time and space. Numerical simulation and inversion of offshore area depth are carried out here; since JONSWAP model can give description of stormy waves in different growth phase, it is suitable for simulation. Besides, some results from measured data detected by OSMAR-X x-band radar located at Longhai of Fujian Province, China, validates this method. The tendency of the average water depths inferred from the radar images is in good agreement with the tide level detected by Xiamen tide station. These promising results suggest the possibility of using OSMAR-X to monitor operationally morphodynamics in coastal zones. This method can be applied to both shore-based and shipborne x-band microwave radar.

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

    Science.gov (United States)

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

    2012-04-01

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

  17. Closed form fourier-based transmit beamforming for MIMO radar

    KAUST Repository

    Lipor, John J.

    2014-05-01

    In multiple-input multiple-output (MIMO) radar setting, it is often desirable to design correlated waveforms such that power is transmitted only to a given set of locations, a process known as beampattern design. To design desired beam-pattern, current research uses iterative algorithms, first to synthesize the waveform covariance matrix, R, then to design the actual waveforms to realize R. In contrast to this, we present a closed form method to design R that exploits discrete Fourier transform and Toeplitz matrix. The resulting covariance matrix fulfills the practical constraints and performance is similar to that of iterative methods. Next, we present a radar architecture for the desired beampattern that does not require the synthesis of covariance matrix nor the design of correlated waveforms. © 2014 IEEE.

  18. Early warning of flash floods based on the weather radar

    Czech Academy of Sciences Publication Activity Database

    Rapant, P.; Kolejka, Jaromír; Inspektor, T.; Batelková, Kateřina; Zapletalová, Jana; Kirchner, Karel

    Szilvásvárad: IEEE, 2015, s. 426-430. ISBN 978-1-4799-7369-9. [International Carpathian Control Conference (ICCC) /16./. Szilvásvárad (HU), 27.05.2015-30.05.2015] R&D Projects: GA MV VG20132015106 Institutional support: RVO:68145535 Keywords : flash flood * weather radar * early warning * geoinformatics Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://dx.doi.org/10.1109/CarpathianCC.2015.7145117

  19. IMPROVED RAIN ATTENUATION ESTIMATION BASED ON DSD AND RADAR DATA

    Czech Academy of Sciences Publication Activity Database

    Fišer, Ondřej

    Toulouse: Centre national d'études spatiales, 2006, ---. [CNES Workshop on Earth-Space Propagation /3./. Toulouse (FR), 25.09.2006-27.09.2006] R&D Projects: GA ČR GA102/04/2153 Institutional research plan: CEZ:AV0Z30420517 Keywords : rain attenuation estimation * radar reflectivity * MWS systems * satellite links * terrestlrial links Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  20. Mobile Ground-Based Radar Sensor for Localization and Mapping: An Evaluation of two Approaches

    Directory of Open Access Journals (Sweden)

    Damien Vivet

    2013-08-01

    Full Text Available This paper is concerned with robotic applications using a ground‐based radar sensor for simultaneous localization and mapping problems. In mobile robotics, radar technology is interesting because of its long range and the robustness of radar waves to atmospheric conditions, making these sensors well‐suited for extended outdoor robotic applications. Two localization and mapping approaches using data obtained from a 360° field of view microwave radar sensor are presented and compared. The first method is a trajectory‐ oriented simultaneous localization and mapping technique, which makes no landmark assumptions and avoids the data association problem. The estimation of the ego‐motion makes use of the Fourier‐Mellin transform for registering radar images in a sequence, from which the rotation and translation of the sensor motion can be estimated. The second approach uses the consequence of using a rotating range sensor in high speed robotics. In such a situation, movement combinations create distortions in the collected data. Velocimetry is achieved here by explicitly analysing these measurement distortions. As a result, the trajectory of the vehicle and then the radar map of outdoor environments can be obtained. The evaluation of experimental results obtained by the two methods is presented on real‐world data from a vehicle moving at 30 km/h over a 2.5 km course.

  1. Aspects of Applying Weather Radar Based Nowcast for Highways in Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Quist, MIchael; Thorndahl, Søren Liedtke

    The Danish road network consists of 73.331 km. of roads. 3.790 km. of these roads are state roads and are considered as major lines of transportation. Although these roads only represent 5% of the total network, 45% of all traffic is moving along these roads. Application of weather radar based...... scenarios. The first is often related to extreme rain intensities while the second can also include less extreme intensities (but maybe higher volume). In both the case of deteriorated traffic conditions and construction phase, a nowcast based on weather radar can provide valuable information on the...... on the movement direction of the precipitation and the direction and speed of the road users. The paper compares and discusses the performance of the nowcast for a selected section of the highway to illustrate the potential in weather radar based forecast for highway applications over long distances....

  2. Radar-based breast cancer detection using a hemispherical antenna array—experimental results

    OpenAIRE

    Klemm, M; Craddock, IJ; Leendertz, JA; Preece, AW; BENJAMIN, R.

    2009-01-01

    In this contribution, an ultrawideband (UWB) microwave system for breast cancer detection is presented. The system is based on a novel hemispherical real-aperture antenna array, which is employed in a multi-static radar-based detection system. The array consists of 16 UWB aperture-coupled stacked-patch antennas located on a section of a hemisphere. The radar system is designed to be used with realistic three-dimensional (3D) breast phantoms, which have been developed, as well as with real bre...

  3. A novel super-resolution imaging method based on stochastic radiation radar array

    International Nuclear Information System (INIS)

    A novel concept of stochastic radiation radar array (SRRA) is proposed to achieve super-resolution in real aperture staring radar imagery. Firstly, the definition of the temporal–spatial stochastic characteristics of the temporal–spatial stochastic radiation field (TSSRF) is presented. Then, a correlated imaging algorithm based on Gram–Schmidt orthogonalization (GSO-CIA) is proposed to reconstruct the target image using the echo signals and TSSRF. By the theoretical analysis, the super-resolution potentiality of staring imaging based on stochastic radiation radar array (SRRA-SI) is verified, which can overcome the resolution limitation of the real antenna aperture. The influences of the random transmitting signals and the configuration of the radar array (the number of array elements, the size array aperture, etc) on the stochastic characteristics of TSSRF are investigated in detail. Finally, numerical simulations are performed and the striking effect of super-resolution, which is more than 20 times compared with traditional real-aperture radar array, is demonstrated. (paper)

  4. Hyper-parameter selection in non-quadratic regularization-based radar image formation

    Science.gov (United States)

    Batu, Özge; Çetin, Müjdat

    2008-04-01

    We consider the problem of automatic parameter selection in regularization-based radar image formation techniques. It has previously been shown that non-quadratic regularization produces feature-enhanced radar images; can yield superresolution; is robust to uncertain or limited data; and can generate enhanced images in non-conventional data collection scenarios such as sparse aperture imaging. However, this regularized imaging framework involves some hyper-parameters, whose choice is crucial because that directly affects the characteristics of the reconstruction. Hence there is interest in developing methods for automatic parameter choice. We investigate Stein's unbiased risk estimator (SURE) and generalized cross-validation (GCV) for automatic selection of hyper-parameters in regularized radar imaging. We present experimental results based on the Air Force Research Laboratory (AFRL) "Backhoe Data Dome," to demonstrate and discuss the effectiveness of these methods.

  5. Novel cued search strategy based on information gain for phased array radar

    Institute of Scientific and Technical Information of China (English)

    Lu Jianbin; Hu Weidong; Xiao Hui; Yu Wenxian

    2008-01-01

    A search strategy based on the maximal information gain principle is presented for the cued search of phased array radars. First, the method for the determination of the cued search region, arrangement of beam positions, and the calculation of the prior probability distribution of each beam position is discussed. And then,two search algorithms based on information gain are proposed using Shannon entropy and Kullback-Leibler entropy,respectively. With the proposed strategy, the information gain of each beam position is predicted before the radar detection, and the observation is made in the beam position with the maximal information gain. Compared with the conventional method of sequential search and confirm search, simulation results show that the proposed search strategy can distinctly improve the search performance and save radar time resources with the same given detection probability.

  6. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials

    Science.gov (United States)

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev

    2016-05-01

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  7. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2015-06-01

    Full Text Available The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS and phase locked loop (PLL. A signal conditioning circuit is used to deal with the coupling effect within the array. The signal processing platform is based on an efficient field programmable gates array (FPGA and digital signal processor (DSP pipeline where a robust beamforming imaging algorithm is running on. The radar system was evaluated through a real field experiment. Imaging capability and real-time performance shown in the results demonstrate the practical feasibility of the implementation.

  8. Radar imaging and holography

    CERN Document Server

    Pasmurov, A

    2005-01-01

    Increasing information content is an important scientific problem in modern observation systems development. Radar, or microwave, imaging can be used for this purpose. This book provides an overview of the field and explains why a unified approach based on wave field processing techniques, including holographic and tomographic approaches, is necessary in high resolution radar design. The authors discuss new areas in imaging radar theory, holographic radar, the questions of estimation and improving radar image quality, and various practical applications.

  9. Use of low power EM radar sensors for speech articulator measurements

    Energy Technology Data Exchange (ETDEWEB)

    Holzrichter, J.F.; Burnett, G.C.

    1997-05-14

    Very low power electromagnetic (EM) wave sensors are being used to measure speech articulator motions such as the vocal fold oscillations, jaw, tongue, and the soft palate. Data on vocal fold motions, that correlate well with established laboratory techniques, as well as data on the jaw, tongue, and soft palate are shown. The vocal fold measurements together with a volume air flow model are being used to perform pitch synchronous estimates of the voiced transfer functions using ARMA (autoregressive moving average) techniques. 6 refs., 5 figs.

  10. A 24GHz Radar Receiver in CMOS

    NARCIS (Netherlands)

    Kwok, K.C.

    2015-01-01

    This thesis investigates the system design and circuit implementation of a 24GHz-band short-range radar receiver in CMOS technology. The propagation and penetration properties of EM wave offer the possibility of non-contact based remote sensing and through-the-wall imaging of distance stationary or

  11. Ground-Based Radar Measurements of the Northern Colorado Snowpack at CLPX- II

    Science.gov (United States)

    Deeb, E. J.; Forster, R. R.; Marshall, H.; Rutter, N.

    2007-12-01

    A stationary, laboratory-grade network analyzer (NA)-based (stepped frequency) radar system and a mobile FMCW (frequency-modulated continuous wave) radar instrument both acquired measurements of the Northern Colorado snowpack during NASA's Cold Land Processes Experiment (CLPX-II, February 2007). These ground- based radar measurements were complimented by manual snow samples and detailed scientific snow pit data. This study concentrates on the preliminary comparison of the two ground-based radar systems while incorporating the associated manual measurements (e.g. stratigraphy, temperature/density profile, grain size estimation, etc.) into the interpretation, on three separate days during Intensive Observation Period 3 of CLPX-II. The stationary radar is based on an Agilent® PNA series vector network analyzer (N5230A) with a 10 MHz to 20 GHz frequency range. A configurable test set was used which allowed for dual linear polarization combinations (HH, VV, HV and VH) to be acquired with the same antenna configuration. Dual-polarized 2-18 GHz horns were connected directly to the NA test set with high phase stability cables at a height of approximately 2 meters, within the far field and with the ability to adjust the incidence angle from nadir to horizontal. Measurements were made from a tripod, with a boom sweeping over an arc of approximately 3 meters. During the same field campaign, a mobile FMCW radar acquired measurements from 4-18 GHz, at HH/HV and VV/VH polarizations, at incidence angles of 30 and 45 degrees, and at a height of 2.3 meters (far-field). An additional portable radar was mounted at a height of 50 cm and 0 degrees incidence, and can be used to estimate snow depth, stratigraphy, and SWE. UNAVCO provided precision differential GPS equipment (Trimble 5700/R7, base station and rover) for the mobile FMCW radar, and the radar measurement and control software was adapted to sync with the cm-level positions, which were recorded every second. These

  12. Radar-based rainfall estimation: Improving Z/R relations through comparison of drop size distributions, rainfall rates and radar reflectivity patterns

    Science.gov (United States)

    Neuper, Malte; Ehret, Uwe

    2014-05-01

    The relation between the measured radar reflectivity factor Z and surface rainfall intensity R - the Z/R relation - is profoundly complex, so that in general one speaks about radar-based quantitative precipitation estimation (QPE) rather than exact measurement. Like in Plato's Allegory of the Cave, what we observe in the end is only the 'shadow' of the true rainfall field through a very small backscatter of an electromagnetic signal emitted by the radar, which we hope has been actually reflected by hydrometeors. The meteorological relevant and valuable Information is gained only indirectly by more or less justified assumptions. One of these assumptions concerns the drop size distribution, through which the rain intensity is finally associated with the measured radar reflectivity factor Z. The real drop size distribution is however subject to large spatial and temporal variability, and consequently so is the true Z/R relation. Better knowledge of the true spatio-temporal Z/R structure therefore has the potential to improve radar-based QPE compared to the common practice of applying a single or a few standard Z/R relations. To this end, we use observations from six laser-optic disdrometers, two vertically pointing micro rain radars, 205 rain gauges, one rawindsonde station and two C-band Doppler radars installed or operated in and near the Attert catchment (Luxembourg). The C-band radars and the rawindsonde station are operated by the Belgian and German Weather Services, the rain gauge data was partly provided by the French, Dutch, Belgian, German Weather Services and the Ministry of Agriculture of Luxembourg and the other equipment was installed as part of the interdisciplinary DFG research project CAOS (Catchment as Organized Systems). With the various data sets correlation analyzes were executed. In order to get a notion on the different appearance of the reflectivity patterns in the radar image, first of all various simple distribution indices (for example the

  13. Identifying Precipitation Types Using Dual-Polarization-Based Radar and Numerical Weather Prediction Model Data

    Science.gov (United States)

    Seo, B. C.; Bradley, A.; Krajewski, W. F.

    2015-12-01

    The recent upgrade of dual-polarization with NEXRAD radars has assisted in improving the characterization of microphysical processes in precipitation and thus has enabled precipitation estimation based on the identified precipitation types. While this polarimetric capability promises the potential for the enhanced accuracy in quantitative precipitation estimation (QPE), recent studies show that the polarimetric estimates are still affected by uncertainties arising from the radar beam geometry/sampling space associated with the vertical variability of precipitation. The authors, first of all, focus on evaluating the NEXRAD hydrometeor classification product using ground reference data (e.g., ASOS) that provide simple categories of the observed precipitation types (e.g., rain, snow, and freezing rain). They also investigate classification uncertainty features caused by the variability of precipitation between the ground and the altitudes where radar samples. Since this variability is closely related to the atmospheric conditions (e.g., temperature) at near surface, useful information (e.g., critical thickness and temperature profile) that is not available in radar observations is retrieved from the numerical weather prediction (NWP) model data such as Rapid Refresh (RAP)/High Resolution Rapid Refresh (HRRR). The NWP retrieved information and polarimetric radar data are used together to improve the accuracy of precipitation type identification at near surface. The authors highlight major improvements and discuss limitations in the real-time application.

  14. RESEARCH ON PERFORMANCE INFLUENCE OF DIRECT-PATH SIGNAL FOR DVB-S BASED PASSIVE RADAR

    Institute of Scientific and Technical Information of China (English)

    Jin Wei; Lü Xiaode; Xiang Maosheng

    2013-01-01

    Passive radar detects moving targets by Cross Ambiguity Function (CAF),which is based on the cross correlation process of the direct-path signal in reference channel and echo signal in receive channel.Thus,the performance of direct-path signal is important to system performance for this type of radar.While the Signal to Noise Ratio (SNR) of direct-path signal is low,it will deteriorate the detection performance.In this paper,how SNR of direct-path signal induces degradation on the SNR of CAF,and how the integration gain affects by integration time are analyzed,both with theoretical analysis and numerical simulation,which are valuable for the R&D of passive radar.

  15. An Optimal Sorting of Pulse Amplitude Sequence Based on the Phased Array Radar Beam Tasks

    Institute of Scientific and Technical Information of China (English)

    Chuan Sheng∗,Yongshun Zhang; Wenlong Lu

    2016-01-01

    The study of phased array radar ( PAR) pulse amplitude sequence characteristics is the key to understand the radar’s working state and its beam’s scanning manner. According to the principle of antenna pattern formation and the searching and tracking modes of beams, this paper analyzes the characteristics and differences of pulse amplitude sequence when the radar beams work in searching and tracking modes respectively. Then an optimal sorting model of pulse amplitude sequence is established based on least⁃squares and curve⁃fitting methods. This method is helpful for acquiring the current working state of the radar and recognizing its instantaneous beam pointing by sorting the pulse amplitude sequence without the necessity to estimate the antenna pattern.

  16. An FPGA Based Implementation of a CFAR Processor Applied to a Pulse-Compression Radar System

    Directory of Open Access Journals (Sweden)

    S.Simić

    2014-04-01

    Full Text Available A hardware architecture that implements a CFAR processor including six variants of the CFAR algorithm based on linear and nonlinear operations for radar applications is presented. Since some implemented CFAR algorithms require sorting the input samples, the two sorting solutions are investigated. The first one is iterative, and it is suitable when incoming data clock is several times less than sorting clock. The second sorter is very fast by exploiting a high degree of parallelism. The architecture is on-line reconfigurable both in terms of CFAR method and in terms of the number of reference and guard cells. The architecture was developed for coherent radar with pulse compression. Besides dealing with surface clutter and multiple target situations, such radar detector is often faced with high side-lobes at the compression filter output when strong target presents in his sight. The results of implementing the architecture on a Field Programmable Gate Array (FPGA are presented and discussed.

  17. An FPGA-based Doppler Processor for a Spaceborne Precipitation Radar

    Science.gov (United States)

    Durden, S. L.; Fischman, M. A.; Johnson, R. A.; Chu, A. J.; Jourdan, M. N.; Tanelli, S.

    2007-01-01

    Measurement of precipitation Doppler velocity by spaceborne radar is complicated by the large velocity of the satellite platform. Even if successive pulses are well correlated, the velocity measurement may be biased if the precipitation target does not uniformly fill the radar footprint. It has been previously shown that the bias in such situations can be reduced if full spectral processing is used. The authors present a processor based on field-programmable gate array (FPGA) technology that can be used for spectral processing of data acquired by future spaceborne precipitation radars. The requirements for and design of the Doppler processor are addressed. Simulation and laboratory test results show that the processor can meet real-time constraints while easily fitting in a single FPGA.

  18. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    OpenAIRE

    Wei Wang,; Dong Liang; Zhihua Wang, Haiyang Yu, Qi Liu

    2015-01-01

    The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coupl...

  19. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    OpenAIRE

    Wei Wang,; Dong Liang; Zhihua Wang; Haiyang Yu; Qi Liu

    2015-01-01

    The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coup...

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

    Science.gov (United States)

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

    2013-05-01

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

  1. SCENARIO AND TARGET SIMULATION FOR A GROUND BASED MULTIFUNCTION PHASED ARRAY RADAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper describes a scenario and target simulation which operates in non real-time to provide full closed-loop operation of the ground based multifunction phased array radar simulation system in support of ballistic missile defence experiments against countermeasure.By simulating the target scattering signature and dynamical signature,this scenario and target simulation provide re- alistic scenario source to evaluate the system performance of multifunction phased array radar,and the key algorithms verification and validation such as target tracking,multi-target imaging and target recognition.

  2. MST data exchange through the NCAR incoherent-scatter radar data base

    Science.gov (United States)

    Richmond, A. D.

    1986-01-01

    One means of making MST (mesosphere stratosphere troposphere) radar data more easily accessible for scientific research by the general scientific community is through a centralized data base. Such a data base can be designed to readily provide information on data availability and quality, and to provide copies of data from any radar in a common format to the user. The ionospheric incoherent scatter community has established a centralized data base at NCAR that may serve not only as a model for a possible MST data base, but also as a catalyst for getting an MST data base started. (Some key elements of the NCAR data base are given.) The NCAR data base can include MST data in the same framework with relatively little extra effort. They are willing to handle MST data on a limited basis in order to permit assessment of community interest and in order to provide some experience with a centralized data base for MST data.

  3. Millimeter-wave silicon-based ultra-wideband automotive radar transceivers

    Science.gov (United States)

    Jain, Vipul

    Since the invention of the integrated circuit, the semiconductor industry has revolutionized the world in ways no one had ever anticipated. With the advent of silicon technologies, consumer electronics became light-weight and affordable and paved the way for an Information-Communication-Entertainment age. While silicon almost completely replaced compound semiconductors from these markets, it has been unable to compete in areas with more stringent requirements due to technology limitations. One of these areas is automotive radar sensors, which will enable next-generation collision-warning systems in automobiles. A low-cost implementation is absolutely essential for widespread use of these systems, which leads us to the subject of this dissertation---silicon-based solutions for automotive radars. This dissertation presents architectures and design techniques for mm-wave automotive radar transceivers. Several fully-integrated transceivers and receivers operating at 22-29 GHz and 77-81 GHz are demonstrated in both CMOS and SiGe BiCMOS technologies. Excellent performance is achieved indicating the suitability of silicon technologies for automotive radar sensors. The first CMOS 22-29-GHz pulse-radar receiver front-end for ultra-wideband radars is presented. The chip includes a low noise amplifier, I/Q mixers, quadrature voltage-controlled oscillators, pulse formers and variable-gain amplifiers. Fabricated in 0.18-mum CMOS, the receiver achieves a conversion gain of 35-38.1 dB and a noise figure of 5.5-7.4 dB. Integration of multi-mode multi-band transceivers on a single chip will enable next-generation low-cost automotive radar sensors. Two highly-integrated silicon ICs are designed in a 0.18-mum BiCMOS technology. These designs are also the first reported demonstrations of mm-wave circuits with high-speed digital circuits on the same chip. The first mm-wave dual-band frequency synthesizer and transceiver, operating in the 24-GHz and 77-GHz bands, are demonstrated. All

  4. Optimum Co-Design for Spectrum Sharing between Matrix Completion Based MIMO Radars and a MIMO Communication System

    Science.gov (United States)

    Li, Bo; Petropulu, Athina P.; Trappe, Wade

    2016-09-01

    Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data that need to be forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between a MIMO-MC radar and a communication system, so that the latter interferes minimally with the former. First, the communication system transmit covariance matrix is designed to minimize the effective interference power (EIP) to the radar receiver, while maintaining certain average capacity and transmit power for the communication system. Two approaches are proposed, namely a noncooperative and a cooperative approach, with the latter being applicable when the radar sampling scheme is known at the communication system. Second, a joint design of the communication transmit covariance matrix and the MIMO-MC radar sampling scheme is proposed, which achieves even further EIP reduction.

  5. Assessment of crop damage and hail risk based on radar hail signature information

    Science.gov (United States)

    Tani, Satyanarayana; Paulitsch, Helmut; Teschl, Reinhard; Süsser-Rechberger, Barbara

    2016-04-01

    Hail storm damage is a major concern to the farmers in the province of Styria, Austria. Each year severe hail storms are causing damages to crops, resulting in losses of millions of euros. High spatiotemporal resolution data are essential to properly assess crop damage information for the insurance sector and also for the better risk assessment. Radar data offer high spatial and temporal resolutions, resulting in very promising option for crop damage assessment and hail risk analysis. This study focuses on the combined analysis of hail signature information from radar and ground measurements for crop hail damage assessment. The days with the high crop hail damage claims were selected for the investigation. Total 16 hail days were assigned to examine the relation between radar-derived products and damages produced by hail in Styria during 2015. 3D single polarization C-band weather radar data and radiosonde freezing level data were used to derive hail kinetic energy flux as well as flux integrated over the whole event. Hail events from ESWD (European Severe Weather Database) and crop damage reports from the Austrian Hail Insurance System were allotted for validation. The spatial distribution maps of total hail kinetic energy were developed to capture the swath and intensity of the hail storms to identify potential hail damage areas. The results show that in most cases radar-based hail signature information well corresponds to the areas where hail events and damage footprints were reported. The radar-based hail signature information is a useful detection option for the assessment of crop damage and hail risk.

  6. Empirical assessment of possible X-band radar installation sites, based on on-site clutter tests

    OpenAIRE

    Goormans, Toon; Willems, Patrick; Jensen, Niels Einar

    2008-01-01

    In a research project of the Hydraulics Laboratory of the Katholieke Universiteit Leuven (K.U.Leuven) for the water company Aquafin, a small, short range, high resolution X-band weather radar, called Local Area Weather Radar - City Radar (LAWR-CR, DHI), is being used for investigation of the spatial rainfall accuracy improvement in urban drainage models. The system is based on standard X-band marine radar technology, making it cost-effective in comparison to other systems. Since marine ra...

  7. 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...

  8. Improved Algorithms for Radar-Based Reconstruction of Asteroid Spin States and Shapes

    Science.gov (United States)

    Greenberg, Adam; Margot, Jean-Luc

    2015-11-01

    Earth-based radar is a powerful tool for gathering information about bodies in the Solar System. Radar observations can dramatically improve the determination of the physical properties and orbital elements of small bodies (such as asteroids and comets). An important development in the past two decades has been the formulation and implementation of algorithms for asteroid shape reconstruction based on radar data.Because of the nature of radar data, recovery of the spin state depends on knowledge of the shape and vice versa. Even with perfect spin state information, certain peculiarities of radar images (such as the two-to-one or several-to-one mapping between surface elements on the object and pixels within the radar image) make recovery of the physical shape challenging. This is a computationally intensive problem, potentially involving hundreds to thousands of free parameters and millions of data points.The method by which radar-based shape and spin state modelling is currently accomplished, a Sequential Parameter Fit (SPF), is relatively slow, and incapable of determining the spin state of an asteroid from radar images without substantial user intervention.We implemented a global-parameter optimizer and Square Root Information Filter (SRIF) into the asteroid-modelling software shape. This optimizer can find shapes more quickly than the current method and can determine the asteroid’s spin state.We ran our new algorithm, along with the existing SPF, through several tests, composed of both real and simulated data. The simulated data were composed of noisy images of procedurally generated shapes, as well as noisy images of existing shape models. The real data included recent observations of both 2000 ET70 and 1566 Icarus.These tests indicate that SRIF is faster and more accurate than SPF. In addition, SRIF can autonomously determine the spin state of an asteroid from a variety of starting conditions, a considerable advance over the existing algorithm. We will

  9. Effects of Cyanobacterial Lipopolysaccharides from <em>Microcystis em>on Glutathione-Based Detoxification Pathways in the Zebrafish (<em>Danio rerioem> Embryo

    Directory of Open Access Journals (Sweden)

    John P. Berry

    2012-05-01

    Full Text Available Cyanobacteria (“blue-green algae” are recognized producers of a diverse array of toxic secondary metabolites. Of these, the lipopolysaccharides (LPS, produced by all cyanobacteria, remain to be well investigated. In the current study, we specifically employed the zebrafish (<em>Danio rerioem> embryo to investigate the effects of LPS from geographically diverse strains of the widespread cyanobacterial genus, <em>Microcystis>, on several detoxifying enzymes/pathways, including glutathione-S-transferase (GST, glutathione peroxidase (GPx/glutathione reductase (GR, superoxide dismutase (SOD, and catalase (CAT, and compared observed effects to those of heterotrophic bacterial (<em>i.e.>, <em>E. coliem> LPS. In agreement with previous studies, cyanobacterial<em> em>LPS significantly reduced GST in embryos exposed to LPS in all treatments. In contrast, GPx moderately increased in embryos exposed to LPS, with no effect on reciprocal GR activity. Interestingly, total glutathione levels were elevated in embryos exposed to <em>Microcystis> LPS, but the relative levels of reduced and oxidized glutathione (<em>i.e.>, GSH/GSSG were, likewise, elevated suggesting that oxidative stress is not involved in the observed effects as typical of heterotrophic bacterial LPS in mammalian systems. In further support of this, no effect was observed with respect to CAT or SOD activity. These findings demonstrate that <em>Microcystis> LPS affects glutathione-based detoxification pathways in the zebrafish embryo, and more generally, that this model is well suited for investigating the apparent toxicophore of cyanobacterial LPS, including possible differences in structure-activity relationships between heterotrophic and cyanobacterial LPS, and teleost fish <em>versus> mammalian systems.

  10. Development of wide band digital receiver for atmospheric radars using COTS board based SDR

    Science.gov (United States)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    Digital receiver extracts the received echo signal information, and is a potential subsystem for atmospheric radar, also referred to as wind profiling radar (WPR), which provides the vertical profiles of 3-dimensional wind vector in the atmosphere. This paper presents the development of digital receiver using COTS board based Software Defined Radio technique, which can be used for atmospheric radars. The developmental work is being carried out at National Atmospheric Research Laboratory (NARL), Gadanki. The digital receiver consists of a commercially available software defined radio (SDR) board called as universal software radio peripheral B210 (USRP B210) and a personal computer. USRP B210 operates over a wider frequency range from 70 MHz to 6 GHz and hence can be used for variety of radars like Doppler weather radars operating in S/C bands, in addition to wind profiling radars operating in VHF, UHF and L bands. Due to the flexibility and re-configurability of SDR, where the component functionalities are implemented in software, it is easy to modify the software to receive the echoes and process them as per the requirement suitable for the type of the radar intended. Hence, USRP B210 board along with the computer forms a versatile digital receiver from 70 MHz to 6 GHz. It has an inbuilt direct conversion transceiver with two transmit and two receive channels, which can be operated in fully coherent 2x2 MIMO fashion and thus it can be used as a two channel receiver. Multiple USRP B210 boards can be synchronized using the pulse per second (PPS) input provided on the board, to configure multi-channel digital receiver system. RF gain of the transceiver can be varied from 0 to 70 dB. The board can be controlled from the computer via USB 3.0 interface through USRP hardware driver (UHD), which is an open source cross platform driver. The USRP B210 board is connected to the personal computer through USB 3.0. Reference (10 MHz) clock signal from the radar master oscillator

  11. Fourier-Based Transmit Beampattern Design Using MIMO Radar

    KAUST Repository

    Lipor, John

    2014-05-01

    In multiple-input multiple-output (MIMO) radar settings, it is often desirable to transmit power only to a given location or set of locations defined by a beampattern. Transmit waveform design is a topic that has received much attention recently, involving synthesis of both the signal covariance matrix,, as well as the actual waveforms. Current methods involve a two-step process of designing via iterative solutions and then using to generate waveforms that fulfill practical constraints such as having a constant-envelope or drawing from a finite alphabet. In this paper, a closed-form method to design for a uniform linear array is proposed that utilizes the discrete Fourier transform (DFT) coefficients and Toeplitz matrices. The resulting covariance matrix fulfills the practical constraints such as positive semidefiniteness and the uniformelemental power constraint and provides performance similar to that of iterative methods, which require a much greater computation time. Next, a transmit architecture is presented that exploits the orthogonality of frequencies at discrete DFT values to transmit a sum of orthogonal signals from each antenna. The resulting waveforms provide a lower mean-square error than current methods at a much lower computational cost, and a simulated detection scenario demonstrates the performance advantages achieved.

  12. Synthetic aperture radar autofocus based on a bilinear model.

    Science.gov (United States)

    Liu, Kuang-Hung; Wiesel, Ami; Munson, David C

    2012-05-01

    Autofocus algorithms are used to restore images in nonideal synthetic aperture radar imaging systems. In this paper, we propose a bilinear parametric model for the unknown image and the nuisance phase parameters and derive an efficient maximum-likelihood autofocus (MLA) algorithm. In the special case of a simple image model and a narrow range of look angles, MLA coincides with the successful multichannel autofocus (MCA). MLA can be interpreted as a generalization of MCA to a larger class of models with a larger range of look angles. We analyze its advantages over previous extensions of MCA in terms of identifiability conditions and noise sensitivity. As a byproduct, we also propose numerical approximations to the difficult constant modulus quadratic program that lies at the core of these algorithms. We demonstrate the superior performance of our proposed methods using computer simulations in both the correct and mismatched system models. MLA performs better than other methods, both in terms of the mean squared error and visual quality of the restored image. PMID:22249713

  13. Constraining CloudSat-based snowfall profiles using surface observations and C-band ground radar

    Science.gov (United States)

    Turk, F. Joseph; Park, Kyung-Won; Haddad, Ziad S.; Rodriguez, Peter; Hudak, David R.

    2011-12-01

    The CloudSat Precipitation Radar, launched in 2006, provides vertical profiles of W-band (94 GHz) reflectivity and is sensitive to falling snow through all but the most intense precipitating cloud structures. Precipitation retrievals of falling snow are affected by a wide diversity of factors describing the medium, such as snow particle shape, size, and composition, which in turn are controlled by ambient factors including the environmental temperature and humidity. Because satellite-based radiometric sounders such as the Microwave Humidity Sounder (MHS) operate without the benefit of coordinated space radar observations, microphysical descriptions of the snow particle medium derived from CloudSat or other radar observations are beneficial to passive microwave (PMW) radiometer-only snowfall retrieval methods. At the coarse scale of these PMW observations, the radiative signal due to the snow is relatively weak compared to the contributions from the atmosphere and the land surface emissivity. Using the C-band (5 GHz) polarization-agile King City radar (WKR) operated by Environment Canada, we examined the vertical structure of winter precipitation events from coordinated overpasses of CloudSat and NOAA 18 (MHS). Two-dimensional video disdrometer observations are used to limit (constrain) the range of the drop-size distribution parameters that are provided through a priori databases to dual-frequency (C/W-band) radar retrieval. Bayesian retrievals using the constrained database produce water content profiles that more closely replicate the observed radar reflectivity profiles and transition smoothly between the single-frequency (CloudSat only) and dual-frequency regions.

  14. An Overview on Development of Passive Radar Based on the Low Frequency Band Digital Broadcasting and TV Signals

    Directory of Open Access Journals (Sweden)

    Wan Xian-rong

    2012-06-01

    Full Text Available Starting from the detection principle and characteristics of passive radar, this paper describes the development of passive radar based on the low frequency band (HF/VHF/UHF digital broadcasting and TV signal. Based on the radio coverage ratio and technical features of digital broadcasting and TV signals, the research status in abroad, especially in Europe, is introduced at first, on experimental systems, technical parameters, and comparative experiments. Then the latest development of passive radars, in different frequency bands in China, both theory and experimental study are presented. Followed is the commentary on the key techniques and problems of Digital Broadcasting-based Passive Radar (DBPR, including the waveform’s properties and its modification, reference signal extraction, multipath clutter rejection, target detection, tracking, and fusion as well as real-time signal processing. Finally, the prospects of development and application of this kind of passive radar are discussed.

  15. Multifractal Modelling of Aircraft Echoes from Low-resolution Radars Based on Structural Functions

    Directory of Open Access Journals (Sweden)

    Qiu Sheng Li

    2013-09-01

    Full Text Available As a kind of complex targets, the nonrigid vibration and attitude change of an aircraft as well as the rotation of its rotating parts will induce complex nonlinear modulation on its echo from low-resolution radars. If one performs the multifractal analysis of measures on an aircraft echo, it may offer a fine description of the dynamic characteristics which induce the echo structure. On basis of introducing multifractal theory based on structural functions, the paper models real recorded aircraft echo data from a low-resolution radar by using the random walk process and the incremental process respectively, and investigates the application of echo multifractal characteristics in aircraft target classification with low-resolution radars. The analysis shows that aircraft echoes from low-resolution radars have clear multifractal characteristics, and one should take an aircraft echo series as a random walk process to perform the multifractal analysis. The experimental results validate the classification method based on multifractal signatures.Defence Science Journal, 2013, 63(5, pp.515-520, DOI:http://dx.doi.org/10.14429/dsj.63.3773

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

    Directory of Open Access Journals (Sweden)

    Antonio Tabasco

    2009-08-01

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

  17. Fuzzy Chance-constrained Programming Based Security Information Optimization for Low Probability of Identification Enhancement in Radar Network Systems

    Directory of Open Access Journals (Sweden)

    C. G. Shi

    2015-04-01

    Full Text Available In this paper, the problem of low probability of identification (LPID improvement for radar network systems is investigated. Firstly, the security information is derived to evaluate the LPID performance for radar network. Then, without any prior knowledge of hostile intercept receiver, a novel fuzzy chance-constrained programming (FCCP based security information optimization scheme is presented to achieve enhanced LPID performance in radar network systems, which focuses on minimizing the achievable mutual information (MI at interceptor, while the attainable MI outage probability at radar network is enforced to be greater than a specified confidence level. Regarding to the complexity and uncertainty of electromagnetic environment in the modern battlefield, the trapezoidal fuzzy number is used to describe the threshold of achievable MI at radar network based on the credibility theory. Finally, the FCCP model is transformed to a crisp equivalent form with the property of trapezoidal fuzzy number. Numerical simulation results demonstrating the performance of the proposed strategy are provided.

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

    OpenAIRE

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

    2016-01-01

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

  19. Feature-Based Correlation and Topological Similarity for Interbeat Interval Estimation Using Ultrawideband Radar.

    Science.gov (United States)

    Sakamoto, Takuya; Imasaka, Ryohei; Taki, Hirofumi; Sato, Toru; Yoshioka, Mototaka; Inoue, Kenichi; Fukuda, Takeshi; Sakai, Hiroyuki

    2016-04-01

    The objectives of this paper are to propose a method that can accurately estimate the human heart rate (HR) using an ultrawideband (UWB) radar system, and to determine the performance of the proposed method through measurements. The proposed method uses the feature points of a radar signal to estimate the HR efficiently and accurately. Fourier- and periodicity-based methods are inappropriate for estimation of instantaneous HRs in real time because heartbeat waveforms are highly variable, even within the beat-to-beat interval. We define six radar waveform features that enable correlation processing to be performed quickly and accurately. In addition, we propose a feature topology signal that is generated from a feature sequence without using amplitude information. This feature topology signal is used to find unreliable feature points, and thus, to suppress inaccurate HR estimates. Measurements were taken using UWB radar, while simultaneously performing electrocardiography measurements in an experiment that was conducted on nine participants. The proposed method achieved an average root-mean-square error in the interbeat interval of 7.17 ms for the nine participants. The results demonstrate the effectiveness and accuracy of the proposed method. The significance of this study for biomedical research is that the proposed method will be useful in the realization of a remote vital signs monitoring system that enables accurate estimation of HR variability, which has been used in various clinical settings for the treatment of conditions such as diabetes and arterial hypertension. PMID:26302507

  20. A flexible implementation for Doppler radar to verify various base-band array signal processing algorithms

    Science.gov (United States)

    Yang, Eunjung; Lee, Jonghyun; Jung, Byungwook; Chun, Joohwan

    2005-09-01

    We describe a flexible hardware system of the Doppler radar which is designed to verify various baseband array signal processing algorithms. In this work we design the Doppler radar system simulator for baseband signal processing in laboratory level. Based on this baseband signal processor, a PN-code pulse doppler radar simulator is developed. More specifically, this simulator consists of an echo signal generation part and a signal processing part. For the echo signal generation part, we use active array structure with 4 elements, and adopt baker coded PCM signal in transmission and reception for digital pulse compression. In the signal processing part, we first transform RF radar pulse to the baseband signal because we use the basebands algorithms using IF sampling. Various digital beamforming algorithms can be adopted as a baseband algorithm in our simulator. We mainly use Multiple Sidelobe Canceller (MSC) with main array antenna elements and auxiliary antenna elements as beamforming and sidelobe canceller algorithm. For Doppler filtering algorithms, we use the FFT. A control set is necessary to control overall system and to manage the timing schedule for the operation.

  1. The 2003-04 Sea Ice Season at Barrow as Seen by Land-Based Radar

    Science.gov (United States)

    Robson, K. L.; Mahoney, A.; Eicken, H.

    2004-12-01

    The objective was to determine the position of the landfast sea ice edge and its morphology throughout the 2003-04 sea ice season near Barrow using a land-based 10 kW, X-band (3 cm) marine radar mounted on a building near the beach at the Ukpeagvik Inupiat Corporation Naval Artcic Research Laboratory (UIC-NARL). This data would then be used to help understand how landfast ice attaches to coast and what causes it to breakaway. An improved understanding together with real-time data available on the internet will provide more information for the safety of whalers, Native people, and the development of nearshore operations. X-band radar does not discriminate well between level ice and open water, since both areas are characterized by very low back-scatter, but it detects ice floes and rough ice that contain surfaces facing towards the radar. It is very effective at monitoring nearshore sea ice motion in a time series of data. Landfast ice can change very rapidly with break-offs and ice shoves occurring in a matter of hours and nearshore pack ice motion can reverse several times in one day. We were able to monitor these changes by the animation of radar images spaced at five-minute intervals. A very similar land-based radar was installed on the beach approximately 500m further towards Barrow between 1973 and 1979 (Shapiro and Metzner, 1991). In a comparison with this earlier study, the 2003-04 season was noted to be much more dynamic and there was less observed pack ice. In conjunction with field measurements, it was also observed that a stable fast ice edge does not necessarily correlate with a grounded ridge, contrary to the World Meteorological Organization's definition of fast ice.

  2. Analysis of Human's Motions Based on Local Mean Decomposition in Through-wall Radar Detection

    Science.gov (United States)

    Lu, Qi; Liu, Cai; Zeng, Zhaofa; Li, Jing; Zhang, Xuebing

    2016-04-01

    Observation of human motions through a wall is an important issue in security applications and search-and rescue. Radar has advantages in looking through walls where other sensors give low performance or cannot be used at all. Ultrawideband (UWB) radar has high spatial resolution as a result of employment of ultranarrow pulses. It has abilities to distinguish the closely positioned targets and provide time-lapse information of targets. Moreover, the UWB radar shows good performance in wall penetration when the inherently short pulses spread their energy over a broad frequency range. Human's motions show periodic features including respiration, swing arms and legs, fluctuations of the torso. Detection of human targets is based on the fact that there is always periodic motion due to breathing or other body movements like walking. The radar can gain the reflections from each human body parts and add the reflections at each time sample. The periodic movements will cause micro-Doppler modulation in the reflected radar signals. Time-frequency analysis methods are consider as the effective tools to analysis and extract micro-Doppler effects caused by the periodic movements in the reflected radar signal, such as short-time Fourier transform (STFT), wavelet transform (WT), and Hilbert-Huang transform (HHT).The local mean decomposition (LMD), initially developed by Smith (2005), is to decomposed amplitude and frequency modulated signals into a small set of product functions (PFs), each of which is the product of an envelope signal and a frequency modulated signal from which a time-vary instantaneous phase and instantaneous frequency can be derived. As bypassing the Hilbert transform, the LMD has no demodulation error coming from window effect and involves no negative frequency without physical sense. Also, the instantaneous attributes obtained by LMD are more stable and precise than those obtained by the empirical mode decomposition (EMD) because LMD uses smoothed local

  3. Reference Signal Reconstruction and Its Impact on Detection Performance of WiFi-based Passive Radar

    Directory of Open Access Journals (Sweden)

    Rao Yunhua

    2016-06-01

    Full Text Available While Wireless Fidelity (WiFi-based passive radar can achieve high detection resolution in both the range and Doppler domain, it is difficult to extract the reference signal because of the complexities of its signal format and application scenarios. In this study, we analyze a typical application of WiFi-based passive radar and discuss different methods for reference signal extraction. Based on the format and features of WiFi signals, we propose a method for reference signal reconstruction, and analyze the influence of the reconstructed reference signal’s performance on detection. The results show that higher reference SNRs generate lower decoding bit rate errors and better clutter suppression with the reconstructed reference signal. Moreover, we propose a method for removing irrelevant signals to avoid the impact on target detection of a non-direct path signal in the receiving signal. The experimental results validate the efficacy of the proposed signal processing method.

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  5. Evaluation of Radar Vegetation Indices for Vegetation Water Content Estimation Using Data from a Ground-Based SMAP Simulator

    Science.gov (United States)

    Srivastava, Prashant K.; O'Neill, Peggy; Cosh, Michael; Lang, Roger; Joseph, Alicia

    2015-01-01

    Vegetation water content (VWC) is an important component of microwave soil moisture retrieval algorithms. This paper aims to estimate VWC using L band active and passive radar/radiometer datasets obtained from a NASA ground-based Soil Moisture Active Passive (SMAP) simulator known as ComRAD (Combined Radar/Radiometer). Several approaches to derive vegetation information from radar and radiometer data such as HH, HV, VV, Microwave Polarization Difference Index (MPDI), HH/VV ratio, HV/(HH+VV), HV/(HH+HV+VV) and Radar Vegetation Index (RVI) are tested for VWC estimation through a generalized linear model (GLM). The overall analysis indicates that HV radar backscattering could be used for VWC content estimation with highest performance followed by HH, VV, MPDI, RVI, and other ratios.

  6. Detection-Discrimination Method for Multiple Repeater False Targets Based on Radar Polarization Echoes

    Directory of Open Access Journals (Sweden)

    Z. W. ZONG

    2014-04-01

    Full Text Available Multiple repeat false targets (RFTs, created by the digital radio frequency memory (DRFM system of jammer, are widely used in practical to effectively exhaust the limited tracking and discrimination resource of defence radar. In this paper, common characteristic of radar polarization echoes of multiple RFTs is used for target recognition. Based on the echoes from two receiving polarization channels, the instantaneous polarization radio (IPR is defined and its variance is derived by employing Taylor series expansion. A detection-discrimination method is designed based on probability grids. By using the data from microwave anechoic chamber, the detection threshold of the method is confirmed. Theoretical analysis and simulations indicate that the method is valid and feasible. Furthermore, the estimation performance of IPRs of RFTs due to the influence of signal noise ratio (SNR is also covered.

  7. Ambiguity Function Analysis and Processing for Passive Radar Based on CDR Digital Audio Broadcasting

    Directory of Open Access Journals (Sweden)

    Zhang Qiang

    2015-01-01

    Full Text Available China Digital Radio (CDR broadcasting is a new standard of digital audio broadcasting of FM frequency (87–108 MHz based on our research and development efforts. It is compatible with the frequency spectrum in analog FM radio and satisfies the requirements for smooth transition from analog to digital signal in FM broadcasting in China. This paper focuses on the signal characteristics and processing methods of radio-based passive radar. The signal characteristics and ambiguity function of a passive radar illumination source are analyzed. The adverse effects on the target detection of the side peaks owing to cyclic prefix, the Doppler ambiguity strips because of signal synchronization, and the range of side peaks resulting from the signal discontinuous spectrum are then studied. Finally, methods for suppressing these side peaks are proposed and their effectiveness is verified by simulations.

  8. Echo simulation of lunar penetrating radar: based on a model of inhomogeneous multilayer lunar regolith structure

    International Nuclear Information System (INIS)

    Lunar Penetrating Radar (LPR) based on the time domain Ultra-Wideband (UWB) technique onboard China's Chang'e-3 (CE-3) rover, has the goal of investigating the lunar subsurface structure and detecting the depth of lunar regolith. An inhomogeneous multi-layer microwave transfer inverse-model is established. The dielectric constant of the lunar regolith, the velocity of propagation, the reflection, refraction and transmission at interfaces, and the resolution are discussed. The model is further used to numerically simulate and analyze temporal variations in the echo obtained from the LPR attached on CE-3's rover, to reveal the location and structure of lunar regolith. The thickness of the lunar regolith is calculated by a comparison between the simulated radar B-scan images based on the model and the detected result taken from the CE-3 lunar mission. The potential scientific return from LPR echoes taken from the landing region is also discussed

  9. Ultrasensitive isolation, identification and quantification of DNA–protein adducts by ELISA-based RADAR assay

    OpenAIRE

    Kiianitsa, Kostantin; Maizels, Nancy

    2014-01-01

    Enzymes that form transient DNA–protein covalent complexes are targets for several potent classes of drugs used to treat infectious disease and cancer, making it important to establish robust and rapid procedures for analysis of these complexes. We report a method for isolation of DNA–protein adducts and their identification and quantification, using techniques compatible with high-throughput screening. This method is based on the RADAR assay for DNA adducts that we previously developed (Kiia...

  10. Calibration Issue in SMART Synthetic Aperture Radar Based on Scan-On-Receive

    OpenAIRE

    Bordoni, Federica; Younis, Marwan; Krieger, Gerhard

    2009-01-01

    A new spaceborne Synthetic Aperture Radar (SAR) system based on SCan-On-REceive (SCORE) algorithm has been recently proposed in order to overcome the trade-off between spatial resolution and swath wide of current SAR systems. The compound architecture of the receiver, which employs multiple channels and Digital Beam-Forming technique, places new challenges to spaceborne SAR internal calibration (Cal) and requires the definition of a new Cal approach. In this paper a novel method for onboard i...

  11. A radar-based hydrological model for flash flood prediction in the dry regions of Israel

    Science.gov (United States)

    Ronen, Alon; Peleg, Nadav; Morin, Efrat

    2014-05-01

    Flash floods are floods which follow shortly after rainfall events, and are among the most destructive natural disasters that strike people and infrastructures in humid and arid regions alike. Using a hydrological model for the prediction of flash floods in gauged and ungauged basins can help mitigate the risk and damage they cause. The sparsity of rain gauges in arid regions requires the use of radar measurements in order to get reliable quantitative precipitation estimations (QPE). While many hydrological models use radar data, only a handful do so in dry climate. This research presents a robust radar-based hydro-meteorological model built specifically for dry climate. Using this model we examine the governing factors of flash floods in the arid and semi-arid regions of Israel in particular and in dry regions in general. The hydrological model built is a semi-distributed, physically-based model, which represents the main hydrological processes in the area, namely infiltration, flow routing and transmission losses. Three infiltration functions were examined - Initial & Constant, SCS-CN and Green&Ampt. The parameters for each function were found by calibration based on 53 flood events in three catchments, and validation was performed using 55 flood events in six catchments. QPE were obtained from a C-band weather radar and adjusted using a weighted multiple regression method based on a rain gauge network. Antecedent moisture conditions were calculated using a daily recharge assessment model (DREAM). We found that the SCS-CN infiltration function performed better than the other two, with reasonable agreement between calculated and measured peak discharge. Effects of storm characteristics were studied using synthetic storms from a high resolution weather generator (HiReS-WG), and showed a strong correlation between storm speed, storm direction and rain depth over desert soils to flood volume and peak discharge.

  12. Performance Enhancement of a Spline-based Method for Extreme Compression of Weather Radar Reflectivity Data

    OpenAIRE

    Mahapatra, Pravas R; Makkapati, Vishnu V

    2005-01-01

    Enhancements are carried out to a contour-based method for extreme compression of weather radar reflectivity data for efficient storage and transmission over low-bandwidth data links. In particular, a new method of systematically adjusting the control points to obtain better reconstruction of the contours using B-Spline interpolation is presented. Further, bit-level manipulations to achieve higher compression ratios are investigated. The efficacy of these enhancements is quantitatively eva...

  13. Embedded DSP-based telehealth radar system for remote in-door fall detection.

    Science.gov (United States)

    Garripoli, Carmine; Mercuri, Marco; Karsmakers, Peter; Jack Soh, Ping; Crupi, Giovanni; Vandenbosch, Guy A E; Pace, Calogero; Leroux, Paul; Schreurs, Dominique

    2015-01-01

    Telehealth systems and applications are extensively investigated nowadays to enhance the quality-of-care and, in particular, to detect emergency situations and to monitor the well-being of elderly people, allowing them to stay at home independently as long as possible. In this paper, an embedded telehealth system for continuous, automatic, and remote monitoring of real-time fall emergencies is presented and discussed. The system, consisting of a radar sensor and base station, represents a cost-effective and efficient healthcare solution. The implementation of the fall detection data processing technique, based on the least-square support vector machines, through a digital signal processor and the management of the communication between radar sensor and base station are detailed. Experimental tests, for a total of 65 mimicked fall incidents, recorded with 16 human subjects (14 men and two women) that have been monitored for 320 min, have been used to validate the proposed system under real circumstances. The subjects' weight is between 55 and 90 kg with heights between 1.65 and 1.82 m, while their age is between 25 and 39 years. The experimental results have shown a sensitivity to detect the fall events in real time of 100% without reporting false positives. The tests have been performed in an area where the radar's operation was not limited by practical situations, namely, signal power, coverage of the antennas, and presence of obstacles between the subject and the antennas. PMID:25291803

  14. Linearity enhancement of TVGA based on adaptive sweep optimisation in monostatic radar receiver

    Science.gov (United States)

    Almslmany, Amir; Wang, Caiyun; Cao, Qunsheng

    2016-08-01

    The limited input dynamic power range of the radar receiver and the power loss due to the targets' ranges are two potential problems in the radar receivers. This paper proposes a model based on the time-varying gain amplifier (TVGA) to compensate the power loss from the targets' ranges, and using the negative impedance compensation technique to enhance the TVGA linearity based on Volterra series. The simulation has been done based on adaptive sweep optimisation (ASO) using advanced design system (ADS) and Matlab. It shows that the suppression of the third-order intermodulation products (IMR3) was carried out for two-tone test, the high-gain accuracy improved by 3 dB, and the high linearity IMR3 improved by 14 dB. The monostatic radar system was tested to detect three targets at different ranges and to compare its probability of detection with the prior models; the results show that the probability of detection has been increased for ASO/TVGA.

  15. The effect of radar-based QPE on the Fractions Skill Score used at the QPF verification

    OpenAIRE

    P. Zacharov; D. Rezacova

    2010-01-01

    In this paper we show the influence of gauge adjustment technique, applied to radar-based rainfalls, on the results of QPF verification. The results were obtained for four convective events which produced heavy local rainfalls and caused local flash floods at the Czech territory. Numerical weather prediction model COSMO was run to obtain rainfall forecast and Fractions Skill Score was employed in the QPF verification. Three different radar-based quantitative precipitation ...

  16. Ground-based weather radar remote sensing of volcanic ash explosive eruptions

    Science.gov (United States)

    Marzano, F. S.; Marchiotto, S.; Barbieri, S.; Giuliani, G.; Textor, C.; Schneider, D. J.

    2009-04-01

    The explosive eruptions of active volcanoes with a consequent formation of ash clouds represent a severe threat in several regions of the urbanized world. During a Plinian or a sub-Plinian eruption the injection of large amounts of fine and coarse rock fragments and corrosive gases into the troposphere and lower stratosphere is usually followed by a long lasting ashfall which can cause a variety of damages. Volcanic ash clouds are an increasing hazard to aviation safety because of growing air traffic volumes that use more efficient and susceptible jet engines. Real-time and areal monitoring of a volcano eruption, in terms of its intensity and dynamics, is not always possible by conventional visual inspections, especially during worse visibility periods which are quite common during eruption activity. Remote sensing techniques both from ground and from space represent unique tools to be exploited. In this respect, microwave weather radars can gather three-dimensional information of atmospheric scattering volumes up several hundreds of kilometers, in all weather conditions, at a fairly high spatial resolution (less than a kilometer) and with a repetition cycle of few minutes. Ground-based radar systems represent one of the best methods for determining the height and volume of volcanic eruption clouds. Single-polarization Doppler radars can measure horizontally-polarized power echo and Doppler shift from which ash content and radial velocity can be, in principle, extracted. In spite of these potentials, there are still several open issues about microwave weather radar capabilities to detect and quantitatively retrieve ash cloud parameters. A major issue is related to the aggregation of volcanic ash particles within the eruption column of explosive eruptions which has been observed at many volcanoes. It influences the residence time of ash in the atmosphere and the radiative properties of the "umbrella" cloud. Numerical experiments are helpful to explore processes

  17. A capon beamforming method for clutter suppression in colocated compressive sensing based MIMO radars

    Science.gov (United States)

    Yu, Yao; Sun, Shunqiao; Petropulu, Athina P.

    2013-05-01

    Compressive sensing (CS) based multi-input multi-output (MIMO) radar systems that explore the sparsity of targets in the target space enable either the same localization performance as traditional methods but with significantly fewer measurements, or significantly improved performance with the same number of measurements. However, the enabling assumption, i.e., the target sparsity, diminishes in the presence of clutter, since clutters is highly correlated with the desire target echoes. This paper proposes an approach to suppress clutter in the context of CS MIMO radars. Assuming that the clutter covariance is known, Capon beamforming is applied at the fusion center on compressively obtained data, which are forwarded by the receive antennas. Subsequently, the target is estimated using CS theory, by exploiting the sparsity of the beamformed signals.

  18. A W-Band Heterodyne FMCW Radar Based on TX IQ-Modulation

    Science.gov (United States)

    Feger, Reinhard; Wagner, Christoph; Stelzer, Andreas

    2011-08-01

    In this paper a method to realize a heterodyne frequency-modulated continuous-wave (FMCW) radar is presented. The proposed principle relies on the use of an inphase/quadrature (IQ)-modulator as single-sideband-mixer to shift the frequency of the FMCW-output away from dc. Since in any IQ-modulator phase and amplitude imbalances occur, the effect of these imbalances will be investigated by deriving the corresponding signal model. Based on this analysis, a method to compensate the imbalances by a predistortion of the modulation signal will be derived. The presented method does not require special test signals or additional hardware, but relies on a standard FMCW measurement onto a calibration target. A prototype radar system was built and used in test measurements to verify the proposed principle. The measurement results show that a suppression of unwanted signal components caused by IQ-imbalances better than 45 dB is achievable.

  19. DOA estimation for monostatic MIMO radar based on unitary root-MUSIC

    Science.gov (United States)

    Wang, Wei; Wang, Xianpeng; Li, Xin; Song, Hongru

    2013-11-01

    Direction of arrival (DOA) estimation is an important issue for monostatic MIMO radar. A DOA estimation method for monostatic MIMO radar based on unitary root-MUSIC is presented in this article. In the presented method, a reduced-dimension matrix is first utilised to transform the high dimension of received signal data into low dimension one. Then, a low-dimension real-value covariance matrix is obtained by forward-backward (FB) averaging and unitary transformation. The DOA of targets can be achieved by unitary root-MUSIC. Due to the FB averaging of received signal data and the eigendecomposition of the real-valued matrix covariance, the proposed method owns better angle estimation performance and lower computational complexity. The simulation results of the proposed method are presented and the performances are investigated and discussed.

  20. Feasibility Study of EO SARs as Opportunity Illuminators in Passive Radars: PAZ-Based Case Study

    Directory of Open Access Journals (Sweden)

    Jose-Luis Bárcena-Humanes

    2015-11-01

    Full Text Available Passive radars exploit the signal transmitted by other systems, known as opportunity illuminators (OIs, instead of using their own transmitter. Due to its almost total invulnerability to natural disasters or physical attacks, satellite OIs are of special interest. In this line, a feasibility study of Earth Observation Synthetic Aperture Radar (EO SAR systems as OIs is carried out taking into consideration signal waveform, availability, bistatic geometry, instrumented coverage area and incident power density. A case study based on the use of PAZ, the first Spanish EO SAR, is presented. PAZ transmitted waveform, operation modes, orbit characteristics and antenna and transmitter parameters are analyzed to estimate potential coverages and resolutions. The study concludes that, due to its working in on-demand operating mode, passive radars based on PAZ-type illuminators can be proposed as complementing tools during the sensor commissioning phase, for system maintenance and for improving its performance by providing additional information about the area of interest and/or increasing the data updating speed, exploiting other sensors during the time PAZ is not available.

  1. Capon-based single-snapshot DOA estimation in monostatic MIMO radar

    Science.gov (United States)

    Hassanien, Aboulnasr; Amin, Moeness G.; Zhang, Yimin D.; Ahmad, Fauzia

    2015-05-01

    We consider the problem of single snapshot direction-of-arrival (DOA) estimation of multiple targets in monostatic multiple-input multiple-output (MIMO) radar. When only a single snapshot is used, the sample covariance matrix of the data becomes non-invertible and, therefore, does not permit application of Capon-based DOA estimation techniques. On the other hand, low-resolution techniques, such as the conventional beamformer, suffer from biased estimation and fail to resolve closely spaced sources. In this paper, we propose a new Capon-based method for DOA estimation in MIMO radar using a single radar pulse. Assuming that the angular locations of the sources are known a priori to be located within a certain spatial sector, we employ multiple transmit beams to focus the transmit energy of multiple orthogonal waveforms within the desired sector. The transmit weight vectors are carefully designed such that they have the same transmit power distribution pattern. As compared to the standard MIMO radar, the proposed approach enables transmitting an arbitrary number of orthogonal waveforms. By using matched-filtering at the receiver, the data associated with each beam is extracted yielding a virtual data snapshot. The total number of virtual snapshots is equal to the number of transmit beams. By choosing the number of transmit beams to be larger than the number of receive elements, it becomes possible to form a full-rank sample covariance matrix. The Capon beamformer is then applied to estimate the DOAs of the targets of interest. The proposed method is shown to have improved DOA estimation performance as compared to conventional single-snapshot DOA estimation methods.

  2. Optimal Power Allocation Algorithm for Radar Network Systems Based on Low Probability of Intercept Optimization(in English

    Directory of Open Access Journals (Sweden)

    Shi Chen-guang

    2014-08-01

    Full Text Available A novel optimal power allocation algorithm for radar network systems is proposed for Low Probability of Intercept (LPI technology in modern electronic warfare. The algorithm is based on the LPI optimization. First, the Schleher intercept factor for a radar network is derived, and then the Schleher intercept factor is minimized by optimizing the transmission power allocation among netted radars in the network to guarantee target-tracking performance. Furthermore, the Nonlinear Programming Genetic Algorithm (NPGA is used to solve the resulting nonconvex, nonlinear, and constrained optimization problem. Numerical simulation results show the effectiveness of the proposed algorithm.

  3. Method for Multiple Targets Tracking in Cognitive Radar Based on Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Yang Jun

    2016-02-01

    Full Text Available A multiple targets cognitive radar tracking method based on Compressed Sensing (CS is proposed. In this method, the theory of CS is introduced to the case of cognitive radar tracking process in multiple targets scenario. The echo signal is sparsely expressed. The designs of sparse matrix and measurement matrix are accomplished by expressing the echo signal sparsely, and subsequently, the restruction of measurement signal under the down-sampling condition is realized. On the receiving end, after considering that the problems that traditional particle filter suffers from degeneracy, and require a large number of particles, the particle swarm optimization particle filter is used to track the targets. On the transmitting end, the Posterior Cramér-Rao Bounds (PCRB of the tracking accuracy is deduced, and the radar waveform parameters are further cognitively designed using PCRB. Simulation results show that the proposed method can not only reduce the data quantity, but also provide a better tracking performance compared with traditional method.

  4. Cardio-respiratory and daily activity monitor based on FMCW Doppler radar embedded in a wheelchair.

    Science.gov (United States)

    Postolache, Octavian; Girão, Pedro Silva; Postolache, Gabriela; Gabriel, Joaquim

    2011-01-01

    Unobtrusive monitoring of the cardio-respiratory and daily activity for wheelchair users became nowadays an important challenge, considering population aging phenomena and the increasing of the elderly with chronic diseases that affect their motion capabilities. This work reports the utilization of FMCW (frequency modulated continuous wave) Doppler radar sensors embedded in a manual wheelchair to measure the cardiac and respiratory activities and the physical activity of the wheelchair user. Another radar sensor is included in the system in order to quantify the motor activity through the wheelchair traveled distance, when the user performs the manual operation of the wheelchair. A conditioning circuit including active filters and a microcontroller based primary processing module was designed and implemented to deliver the information through Bluetooth communication protocol to an Android OS tablet computer. The main capabilities of the software developed using Android SDK and Java were the signal processing of Doppler radar measurement channel signals, graphical user interface, data storage and Wi-Fi data synchronization with remote physiological and physical activity database. PMID:22254706

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

    Science.gov (United States)

    Montgomery, Donald R. (Editor)

    1996-01-01

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

  6. Predictability of heavy sub-hourly precipitation amounts for a weather radar based nowcasting system

    Science.gov (United States)

    Bech, Joan; Berenguer, Marc

    2015-04-01

    Heavy precipitation events and subsequent flash floods are one of the most dramatic hazards in many regions such as the Mediterranean basin as recently stressed in the HyMeX (HYdrological cycle in the Mediterranean EXperiment) international programme. The focus of this study is to assess the quality of very short range (below 3 hour lead times) precipitation forecasts based on weather radar nowcasting system. Specific nowcasting amounts of 10 and 30 minutes generated with a nowcasting technique (Berenguer et al 2005, 2011) are compared against raingauge observations and also weather radar precipitation estimates observed over Catalonia (NE Spain) using data from the Meteorological Service of Catalonia and the Water Catalan Agency. Results allow to discuss the feasibility of issuing warnings for different precipitation amounts and lead times for a number of case studies, including very intense convective events with 30minute precipitation amounts exceeding 40 mm (Bech et al 2005, 2011). As indicated by a number of verification scores single based radar precipitation nowcasts decrease their skill quickly with increasing lead times and rainfall thresholds. This work has been done in the framework of the Hymex research programme and has been partly funded by the ProFEWS project (CGL2010-15892). References Bech J, N Pineda, T Rigo, M Aran, J Amaro, M Gayà, J Arús, J Montanyà, O van der Velde, 2011: A Mediterranean nocturnal heavy rainfall and tornadic event. Part I: Overview, damage survey and radar analysis. Atmospheric Research 100:621-637 http://dx.doi.org/10.1016/j.atmosres.2010.12.024 Bech J, R Pascual, T Rigo, N Pineda, JM López, J Arús, and M Gayà, 2007: An observational study of the 7 September 2005 Barcelona tornado outbreak. Natural Hazards and Earth System Science 7:129-139 http://dx.doi.org/10.5194/nhess-7-129-2007 Berenguer M, C Corral, R Sa0nchez-Diezma, D Sempere-Torres, 2005: Hydrological validation of a radar based nowcasting technique. Journal of

  7. Quasi-Coherent Noise Jamming to LFM Radar Based on Pseudo-random Sequence Phase-modulation

    OpenAIRE

    Tai, N.; Pan, Y. J.; Yuan, N. C.

    2015-01-01

    A novel quasi-coherent noise jamming method is proposed against linear frequency modulation (LFM) signal and pulse compression radar. Based on the structure of digital radio frequency memory (DRFM), the jamming signal is acquired by the pseudo-random sequence phase-modulation of sampled radar signal. The characteristic of jamming signal in time domain and frequency domain is analyzed in detail. Results of ambiguity function indicate that the blanket jamming effect along the range direction wi...

  8. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  9. A convection climatology of the inner alpine region based on radar and lightning data

    Science.gov (United States)

    Meyer, Vera; Tüchler, Lukas; Tollardo, Mauro; Cenzon, Giovanni; Domenichini, Francesco

    2014-05-01

    A convection climatology of the inner alpine region covering Western Austria and North Italy is generated from five years radar and lightning data. The Austrian thunderstorm nowcasting tool (A-TNT) is employed to identify and track convective cells based on a uniform MaxCAPPI composite and lightning intensity maps following the method of the thunderstorm tracking and nowcasting algorithm ec-TRAM [1]. The algorithm identifies and monitors regions of intense precipitation and lightning activity separately by analyzing sequential two-dimensional intensity maps of radar precipitation rates and lightning densities, respectively. Each data source is processed by a stand-alone identification and tracking procedure, where the two separate tracking results are combined to comprehensive "convective cells" in a subsequent, final step. With this approach lightning data is used as a second, independent and complementing data source to improve storm identification and tracking in those regions where radar data is not or poorly available and to compensate for occasional data failures. Furthermore, pure convective precipitation can be distinguished from thunderstorms which also exhibit electrical activity. Intensive precipitation cells are identified based on the uniform radar MaxCAPPI composite of the core region which is generated at ZAMG on a 1 km X 1 km basic grid. Lightning data are provided by the European lightning detection network EUCLID (www.euclid.org). A-TNT is run with a temporal resolution of 5 minutes. First results of the convection climatology will be presented. Regions of preferred storm initiation and dissipation are investigated with respect to diurnal and seasonal aspects as well as different storm classes. Due to the rather short data archive the work focus on the documentation of the current situation. The presented work is performed within the framework of the INTERREG IV project 'Past, Present and Perspective Climate of Tirol, South Tyrol-Alto Adige and

  10. Toward a Framework for Systematic Error Modeling of NASA Spaceborne Radar with NOAA/NSSL Ground Radar-Based National Mosaic QPE

    Science.gov (United States)

    Kirstettier, Pierre-Emmanual; Honh, Y.; Gourley, J. J.; Chen, S.; Flamig, Z.; Zhang, J.; Howard, K.; Schwaller, M.; Petersen, W.; Amitai, E.

    2011-01-01

    Characterization of the error associated to satellite rainfall estimates is a necessary component of deterministic and probabilistic frameworks involving space-born passive and active microwave measurement") for applications ranging from water budget studies to forecasting natural hazards related to extreme rainfall events. We focus here on the error structure of NASA's Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) quantitative precipitation estimation (QPE) at ground. The problem is addressed by comparison of PR QPEs with reference values derived from ground-based measurements using NOAA/NSSL ground radar-based National Mosaic and QPE system (NMQ/Q2). A preliminary investigation of this subject has been carried out at the PR estimation scale (instantaneous and 5 km) using a three-month data sample in the southern part of US. The primary contribution of this study is the presentation of the detailed steps required to derive trustworthy reference rainfall dataset from Q2 at the PR pixel resolution. It relics on a bias correction and a radar quality index, both of which provide a basis to filter out the less trustworthy Q2 values. Several aspects of PR errors arc revealed and quantified including sensitivity to the processing steps with the reference rainfall, comparisons of rainfall detectability and rainfall rate distributions, spatial representativeness of error, and separation of systematic biases and random errors. The methodology and framework developed herein applies more generally to rainfall rate estimates from other sensors onboard low-earth orbiting satellites such as microwave imagers and dual-wavelength radars such as with the Global Precipitation Measurement (GPM) mission.

  11. Video segmentation using multiple features based on EM algorithm

    Institute of Scientific and Technical Information of China (English)

    张风超; 杨杰; 刘尔琦

    2004-01-01

    Object-based video segmentation is an important issue for many multimedia applications. A video segmentation method based on EM algorithm is proposed. We consider video segmentation as an unsupervised classification problem and apply EM algorithm to obtain the maximum-likelihood estimation of the Gaussian model parameters for model-based segmentation. We simultaneously combine multiple features (motion, color) within a maximum likelihood framework to obtain accurate segment results. We also use the temporal consistency among video frames to improve the speed of EM algorithm. Experimental results on typical MPEG-4 sequences and real scene sequences show that our method has an attractive accuracy and robustness.

  12. Physics-based Multi-resolution Radar-Radiometer Soil Moisture Estimation within the SMAP Mission Framework

    Science.gov (United States)

    Akbar, R.; Moghaddam, M.

    2014-12-01

    To further develop our understanding of global carbon and water cycles and to support the NASA Soil Moisture Active-Passive (SMAP) mission efforts have been made to develop joint and combined radar and radiometer soil moisture estimation algorithms. Taking advantage of the complimentary sensitivities of radar backscatter and brightness temperature to soil moisture and vegetation has the potential to greatly improve global soil moisture estimates. With the advent of SMAP, not only combing radar and radiometer information is of interest, combing multi-resolution data becomes critical. The work presented here will discuss methods to estimate soil moisture within the SMAP framework via a global optimization technique. Fine resolution radar backscatter measurements (3 km for SMAP) are combined with coarse resolution radiometer data (36 km for SMAP) in a joint cost function. Brightness temperature disaggregation and soil moisture estimation are then performed at the radar resolution. Furthermore, to capture the underlying physics of emission and scattering within the cost function, physics-based forward models which link emission and scattering from first principles are employed. The resulting effect is the ability to define a parameter kernel shared between emission and scattering models. Preliminary investigation yields improved soil moisture estimation when radar and radiometer information are used jointly. Furthermore, over a wide range of soil moisture (0.04 - 0.4 cm3/cm3) and vegetation (0- 5 kg/m2) physics based joint estimation yields the least retrieval errors.

  13. Intercomparison of Vertical Structure of Storms Revealed by Ground-Based (NMQ and Spaceborne Radars (CloudSat-CPR and TRMM-PR

    Directory of Open Access Journals (Sweden)

    Veronica M. Fall

    2013-01-01

    Full Text Available Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR and Ku-band Precipitation Radar (PR, which are onboard NASA’s CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE. This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors’ type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts.

  14. Radar-based Flood Warning System for Houston, Texas and Its Performance Evaluation

    Science.gov (United States)

    Fang, N.; Bedient, P.

    2009-12-01

    Houston has a long history of flooding problems as a serious nature. For instance, Houstonians suffered from severe flood inundation during Tropical Storm Allison in 2001 and Hurricane Ike in 2008. Radar-based flood warning systems as non-structural tools to provide accurate and timely warnings to the public and private entities are greatly needed for urban areas prone to flash floods. Fortunately, the advent of GIS, radar-based rainfall estimation using NEXRAD, and real-time delivery systems on the internet have allowed flood alert systems to provide important advanced warning of impending flood conditions. Thus, emergency personnel can take proper steps to mitigate against catastrophic losses. The Rice and Texas Medical Center (TMC) Flood Alert System (FAS2) has been delivering warning information with 2 to 3 hours of lead time to facility personnel in a readily understood format for more than 40 events since 1997. The system performed well during these major rainfall events with R square value of 93%. The current system has been improved by incorporating a new hydraulic prediction tool - FloodPlain Map Library (FPML). The FPML module aims to provide visualized information such as floodplain maps and water surface elevations instead of just showing hydrographs in real time based on NEXRAD radar rainfall data. During Hurricane Ike (September, 2008), FAS2 successfully provided precise and timely flood warning information to TMC with the peak flow difference of 3.6% and the volume difference of 5.6%; timing was excellent for this double-peaked event. With the funding from the Texas Department of Transportation, a similar flood warning system has been developed at a critical transportation pass along Highway 288 in Houston, Texas. In order to enable emergency personnel to begin flood preparation with as much lead time as possible, FAS2 is being used as a prototype to develop warning system for other flood-prone areas such as City of Sugar Land.

  15. Migration-based SAR imaging for ground-penetrating radar systems

    Science.gov (United States)

    Gu, Kunlong; Wang, Gang; Li, Jian

    2003-09-01

    We consider migration based synthetic aperture radar (SAR) imaging of surfaced or shallowly buried objects using both down-looking and forward-looking ground penetrating radar (GPR). The well-known migration approaches devised to image the interior of the earth are based on wave equations and have been widely and successfully used in seismic signal processing for oil exploration for decades. They have exhibited great potentials and convenience to image the underground objects buried in complicated propagation medium. Compared to the ray-tracing based SAR imaging methods, the migration based SAR imaging approaches are more suited for the imaging of the underground objects due to their simple and direct treatment of the oblique incidence at the air-ground interface and the propagation velocity variation in the soil. In this paper, we apply the phase-shift migration approach to both the constant-offset and the common-shot experimental data collected by the PSI (Planning Systems Inc.) GPR systems. We will address the spatial aliasing problems related to the application of migration to the GPR data and the spatial zero-padding approach to circumvent the problem successfully.

  16. Registration-Based Range-Dependence Compensation for Bistatic STAP Radars

    Directory of Open Access Journals (Sweden)

    Lapierre Fabian D

    2005-01-01

    Full Text Available We address the problem of detecting slow-moving targets using space-time adaptive processing (STAP radar. Determining the optimum weights at each range requires data snapshots at neighboring ranges. However, in virtually all configurations, snapshot statistics are range dependent, meaning that snapshots are nonstationary with respect to range. This results in poor performance. In this paper, we propose a new compensation method based on registration of clutter ridges and designed to work on a single realization of the stochastic snapshot at each range. The method has been successfully tested on simulated, stochastic snapshots. An evaluation of performance is presented.

  17. Solving multi-object radar cross section based on wide-angle parabolic equation method

    Institute of Scientific and Technical Information of China (English)

    Huang Zhixiang; Wu Qiong; Wu Xianliang

    2006-01-01

    Based on a Padé approximation, a wide-angle parabolic equation method is introduced for computing the multiobject radar cross section (RCS) for the first time. The method is a paraxial version of the scalar wave equation, which solves the field by marching them along the paraxial direction. Numerical results show that a single wide-angle parabolic equation run can compute multi-object RCS efficiently for angles up to 45°.The method provides a new and efficient numerical method for computation electromagnetics.

  18. Single channel source separation of radar fuze mixed signal based on phase difference analysis

    Institute of Scientific and Technical Information of China (English)

    Hang ZHU; Shu-ning ZHANG; Hui-chang ZHAO

    2014-01-01

    A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze. This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals, solve the candidate data set by the mixing coefficients and signal analytical form, and resolve the problem of vector ambiguity by analyzing the phase differences. The signal separation is realized by exchanging data of the solutions. The waveform similarity coefficients are calculated, and the timeefrequency dis-tributions of separated signals are analyzed. The results show that the proposed method is effective.

  19. Low velocity target detection based on time-frequency image for high frequency ground wave radar

    Institute of Scientific and Technical Information of China (English)

    YAN Songhua; WU Shicai; WEN Biyang

    2007-01-01

    The Doppler spectral broadening resulted from non-stationary movement of target and radio-frequency interference will decrease the veracity of target detection by high frequency ground wave(HEGW)radar.By displaying the change of signal energy on two dimensional time-frequency images based on time-frequency analysis,a new mathematical morphology method to distinguish target from nonlinear time-frequency curves is presented.The analyzed results from the measured data verify that with this new method the target can be detected correctly from wide Doppler spectrum.

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

    Institute of Scientific and Technical Information of China (English)

    Haixia Xu; Zheng Tian; Mingtao Ding

    2008-01-01

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

  1. GLUE Based Marine X-Band Weather Radar Data Calibration and Uncertainty Estimation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Beven, Keith; Thorndahl, Søren Liedtke;

    2015-01-01

    The Generalized Likelihood Uncertainty Estimation methodology (GLUE) is investigated for radar rainfall calibration and uncertainty assessment. The method is used to calibrate radar data collected by a Local Area Weather Radar (LAWR). In contrast to other LAWR data calibrations, the method combines...

  2. Application of model-based spectral analysis to wind-profiler radar observations

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, E. [ENS, Cachan (France). LESiR; Petitdidier, M.; Corneil, W. [CETP, Velizy (France); Adnet, C. [THALES Air Dfense, Bagneux (France); Larzabal, P. [ENS, Cachan (France). LESiR; IUT, Cachan (France). CRIIP

    2001-08-01

    A classical way to reduce a radar's data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometer echo..) exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunderstorms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar's data. (orig.)

  3. Synthetic Aperture Radar - Hardware Development

    OpenAIRE

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

    2009-01-01

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

  4. A Comparison of Satellite-Based Radar and Passive Microwave Estimates of Global Wilson Current Source

    Science.gov (United States)

    Peterson, M. J.; Deierling, W.; Liu, C.; Mach, D. M.; Kalb, C. P.

    2014-12-01

    A passive microwave algorithm for estimating the electrical footprint of charged clouds has been developed and applied to satellite observations taken by the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), which has a domain spanning the entire tropics up to 36 degrees latitude, and compared with lightning-based estimates of global electricity and the Carnegie curve. While these results show considerable agreement with historical observations for convective storms, this method has difficulty characterizing electricity in stratiform clouds and storms at different stages of the convective lifecycle. The algorithm also does not take advantage of the full suite of observations available in the 16-year TRMM dataset, which also includes Precipitation Radar (PR) observations of the structure of storms overflown by the satellite. As a first step towards building an algorithm that can characterize electrical input to the Global Electric Circuit (GEC) from a wide variety of storms across the globe, this study compares passive microwave-based approximations of global electricity with precipitation radar-based approximations in order to determine the relative skill each platform has in describing the "battery" of the GEC and to identify a possible pathway towards a combined metric that can use the strengths of both instruments to better describe electrified clouds.

  5. Comparison of Coordinated Satellite and Ground-based X-Band Radar Collections for the Retrieval of Snow Parameters

    Science.gov (United States)

    Deeb, E. J.; Marshall, H.; LeWinter, A. L.; Finnegan, D. C.; Deems, J. S.; Landry, C.

    2012-12-01

    In many regions of the world, snow is a major source of runoff contributing to human existence/sustenance, agriculture, and industry. The uncertainties in quantifying snow mass at both spatial and temporal scales have limited the vital management of this significant component to the global water cycle. With the sensitivity of radar backscatter to physical properties of snow at higher frequencies and the availability of high resolution commercial satellite imaging radars at X-Band frequencies (e.g. 9.6 GHz), snow experiments have been conducted to examine these relationships at finer spatial and temporal scales. For the past several winters, satellite radar acquisitions (at X-Band with co- and cross-polarizations) have been coordinated with ground-based radar collections within a well-instrumented southwestern Colorado basin exhibiting a wide range of snow conditions. Snow-free satellite radar collections (at X-Band with the same viewing geometry) have also been acquired to separate the backscatter contributions of the snow volume from the underlying background target. Ancillary data sets including ground-based LiDAR-derived snow depths and scientific snow pit sampling are also incorporated into the analysis. Despite the fact that it may not be possible to retrieve snow water equivalent from multi-polarization X-Band frequency alone, preliminary results of these comparisons are shown where the ground-based radar transects overlap the satellite radar coverage. Snow parameters such as saturated surface or internal snow layers, snow surface and stratigraphic roughness, and grain size variations may be of particular interest.

  6. Ultrasensitive isolation, identification and quantification of DNA-protein adducts by ELISA-based RADAR assay.

    Science.gov (United States)

    Kiianitsa, Kostantin; Maizels, Nancy

    2014-07-01

    Enzymes that form transient DNA-protein covalent complexes are targets for several potent classes of drugs used to treat infectious disease and cancer, making it important to establish robust and rapid procedures for analysis of these complexes. We report a method for isolation of DNA-protein adducts and their identification and quantification, using techniques compatible with high-throughput screening. This method is based on the RADAR assay for DNA adducts that we previously developed (Kiianitsa and Maizels (2013) A rapid and sensitive assay for DNA-protein covalent complexes in living cells. Nucleic Acids Res., 41:e104), but incorporates three key new steps of broad applicability. (i) Silica-assisted ethanol/isopropanol precipitation ensures reproducible and efficient recovery of DNA and DNA-protein adducts at low centrifugal forces, enabling cell culture and DNA precipitation to be carried out in a single microtiter plate. (ii) Rigorous purification of DNA-protein adducts by a procedure that eliminates free proteins and free nucleic acids, generating samples suitable for detection of novel protein adducts (e.g. by mass spectroscopy). (iii) Identification and quantification of DNA-protein adducts by direct ELISA assay. The ELISA-based RADAR assay can detect Top1-DNA and Top2a-DNA adducts in human cells, and gyrase-DNA adducts in Escherichia coli. This approach will be useful for discovery and characterization of new drugs to treat infectious disease and cancer, and for development of companion diagnostics assays for individualized medicine. PMID:24914050

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

    Science.gov (United States)

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

    2016-01-01

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

  8. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground-based weather radar network over Sweden

    Directory of Open Access Journals (Sweden)

    L. Norin

    2015-12-01

    Full Text Available Accurate snowfall estimates are important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain gauges to estimate precipitation in this context. In particular, the Cloud Profiling Radar (CPR on board CloudSat is proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and its ability to provide near-global vertical structure. CloudSat snowfall estimates play a particularly important role in the high-latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. In this paper, snowfall estimates from two observing systems – Swerad, the Swedish national weather radar network, and CloudSat – are compared. Swerad offers a well-calibrated data set of precipitation rates with high spatial and temporal resolution, at very high latitudes. The measurements are anchored to rain gauges and provide valuable insights into the usefulness of CloudSat CPR's snowfall estimates in the polar regions. In total, 7.2 × 105 matchups of CloudSat and Swerad observations from 2008 through 2010 were intercompared, covering all but the summer months (June to September. The intercomparison shows encouraging agreement between the two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46–82 km, where the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station, as Swerad's sensitivity decreases as a function of distance. Swerad also tends to overshoot low-level precipitating systems further away from the station

  9. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground based weather radar network over Sweden

    Directory of Open Access Journals (Sweden)

    L. Norin

    2015-08-01

    Full Text Available To be able to estimate snowfall accurately is important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain-gauges to estimate precipitation in this context. The Cloud Profiling Radar (CPR onboard CloudSat is especially proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and ability to provide near-global vertical structure. The importance of having snowfall estimates from CloudSat/CPR further increases in the high latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. Here we intercompared snowfall estimates from two observing systems, CloudSat and Swerad, the Swedish national weather radar network. Swerad offers one of the best calibrated data sets of precipitation amount at very high latitudes that are anchored to rain-gauges and that can be exploited to evaluate usefulness of CloudSat/CPR snowfall estimates in the polar regions. In total 7.2×105 matchups of CloudSat and Swerad over Sweden were inter-compared covering all but summer months (October to May from 2008 to 2010. The intercomparison shows encouraging agreement between these two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46–82 km, when the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station as Swerad's sensitivity decreases as a function of distance and Swerad also tends to overshoots low level precipitating systems further away from the station, leading to underestimation of snowfall rate and

  10. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground-based weather radar network over Sweden

    Science.gov (United States)

    Norin, L.; Devasthale, A.; L'Ecuyer, T. S.; Wood, N. B.; Smalley, M.

    2015-12-01

    Accurate snowfall estimates are important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain gauges to estimate precipitation in this context. In particular, the Cloud Profiling Radar (CPR) on board CloudSat is proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and its ability to provide near-global vertical structure. CloudSat snowfall estimates play a particularly important role in the high-latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. In this paper, snowfall estimates from two observing systems - Swerad, the Swedish national weather radar network, and CloudSat - are compared. Swerad offers a well-calibrated data set of precipitation rates with high spatial and temporal resolution, at very high latitudes. The measurements are anchored to rain gauges and provide valuable insights into the usefulness of CloudSat CPR's snowfall estimates in the polar regions. In total, 7.2 × 105 matchups of CloudSat and Swerad observations from 2008 through 2010 were intercompared, covering all but the summer months (June to September). The intercomparison shows encouraging agreement between the two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46-82 km), where the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station, as Swerad's sensitivity decreases as a function of distance. Swerad also tends to overshoot low-level precipitating systems further away from the station, leading to an

  11. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground based weather radar network over Sweden

    Science.gov (United States)

    Norin, L.; Devasthale, A.; L'Ecuyer, T. S.; Wood, N. B.; Smalley, M.

    2015-08-01

    To be able to estimate snowfall accurately is important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain-gauges to estimate precipitation in this context. The Cloud Profiling Radar (CPR) onboard CloudSat is especially proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and ability to provide near-global vertical structure. The importance of having snowfall estimates from CloudSat/CPR further increases in the high latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. Here we intercompared snowfall estimates from two observing systems, CloudSat and Swerad, the Swedish national weather radar network. Swerad offers one of the best calibrated data sets of precipitation amount at very high latitudes that are anchored to rain-gauges and that can be exploited to evaluate usefulness of CloudSat/CPR snowfall estimates in the polar regions. In total 7.2×105 matchups of CloudSat and Swerad over Sweden were inter-compared covering all but summer months (October to May) from 2008 to 2010. The intercomparison shows encouraging agreement between these two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46-82 km), when the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station as Swerad's sensitivity decreases as a function of distance and Swerad also tends to overshoots low level precipitating systems further away from the station, leading to underestimation of snowfall rate and occasionally missing

  12. Simulation Analysis and Model of Current Retrieval Based on Marine Radar Sea Clutter Images

    Directory of Open Access Journals (Sweden)

    Liqiang Liu

    2014-01-01

    Full Text Available Using the sea clutter image from X-Band radar for current retrieval is an effective way of obtaining information on ocean currents. Traditional methods used for current retrieval have been based on the least squares algorithm, which is not only simple and efficient but also generally speaking accurate. In order to improve the precision of current retrieval, this paper has, as its goal, the study of the used radar connected with sea clutter imaging for current retrieval, with the particle swarm optimization (PSO algorithm being proposed. This method is achieved by obtaining a three-dimensional image spectrum, taking the high-order dispersion relation model as the theoretical distribution model of the wave energy points of three-dimensional image spectra, using a forward model within the PSO framework, and considering the requirements of the order of the model, weights and optimal distribution of the energy points, and so on in fitness function. Simulation results show that, compared with the traditional ILSM methods, the method provided in this paper is more flexible, with a capacity for a high dispersion relationship order, higher precision, and an increased stability in terms of current inversion.

  13. An Entropy-Based Propagation Speed Estimation Method for Near-Field Subsurface Radar Imaging

    Directory of Open Access Journals (Sweden)

    Pistorius Stephen

    2010-01-01

    Full Text Available During the last forty years, Subsurface Radar (SR has been used in an increasing number of noninvasive/nondestructive imaging applications, ranging from landmine detection to breast imaging. To properly assess the dimensions and locations of the targets within the scan area, SR data sets have to be reconstructed. This process usually requires the knowledge of the propagation speed in the medium, which is usually obtained by performing an offline measurement from a representative sample of the materials that form the scan region. Nevertheless, in some novel near-field SR scenarios, such as Microwave Wood Inspection (MWI and Breast Microwave Radar (BMR, the extraction of a representative sample is not an option due to the noninvasive requirements of the application. A novel technique to determine the propagation speed of the medium based on the use of an information theory metric is proposed in this paper. The proposed method uses the Shannon entropy of the reconstructed images as the focal quality metric to generate an estimate of the propagation speed in a given scan region. The performance of the proposed algorithm was assessed using data sets collected from experimental setups that mimic the dielectric contrast found in BMI and MWI scenarios. The proposed method yielded accurate results and exhibited an execution time in the order of seconds.

  14. PERFORMANCE ANALYSIS OF A MODIFIED CFAR BASED RADAR DETECTOR UNDER PEARSON DISTRIBUTED CLUTTER

    Directory of Open Access Journals (Sweden)

    Amritakar Mandal

    2014-12-01

    Full Text Available An adaptive target detector in radar system is used to extract targets from background in noisy environment of unknown statistics. The constant false alarm rate (CFAR is well known detection algorithm that is being used in almost every modern radar. The cell averaging CFAR is the optimum detector in homogeneous clutter environment when the refence cells have identically independent and exponentially distributed signals. The performance of CA CFAR degrades seriously when clutter power substantially varies in non-homogeneous background. To overcome the performance degradation, a non-linear compression technique based CFAR has been introduced for adaptive thresholding to meet the challenges of target detection from various degrees of Pearson distributed non-homogeneous clutter. Extensive MATLAB simulations have been done using various levels of clutter input to show the effectiveness of the proposed design. Improvement in Signal-to-Noise ratio (SNR has been achieved using Swerling I model for Rayleigh fluctuating target in the backdrop of heavy clutter.

  15. A New MCMC Sampling Based Segment Model for Radar Target Recognition

    Directory of Open Access Journals (Sweden)

    M. Hadavi

    2015-04-01

    Full Text Available One of the main tools in radar target recognition is high resolution range profile (HRRP‎. ‎However‎, ‎it is very sensitive to the aspect angle‎. ‎One solution to this problem is to assume the consecutive samples of HRRP identically independently distributed (IID in small frames of aspect angles‎, ‎an assumption which is not true in reality‎. ‎However, b‎‎ased on this assumption‎, ‎some models have been developed to characterize the sequential information contained in the multi-aspect radar echoes‎. ‎Therefore‎, ‎they only consider the short dependency between consecutive samples‎. ‎Here‎, ‎we propose an alternative model‎, ‎the segment model‎, ‎to address the shortcomings of these assumptions‎. ‎In addition‎, ‎using a Markov chain Monte-Carlo (MCMC based Gibbs sampler as an iterative approach to estimate the parameters of the segment model‎, ‎we will show that the proposed method is able to estimate the parameters with quite satisfying accuracy and computational load‎.

  16. Determining Best Method for Estimating Observed Level of Maximum Detrainment based on Radar Reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Carletta, Nicholas; Mullendore, Gretchen; Starzec, Mariusz; Xi, Baike; Feng, Zhe; Dong, Xiquan

    2016-07-25

    Convective mass transport is the transport of mass from near the surface up to the upper troposphere and lower stratosphere (UTLS) by a deep convective updraft. This transport can alter the chemical makeup and water vapor balance of the UTLS, which affects cloud formation and the radiative properties of the atmosphere. It is therefore important to understand the exact altitudes at which mass is detrained from convection. The purpose of this study was to improve upon previously published methodologies for estimating the level of maximum detrainment (LMD) within convection using data from a single ground-based radar. Four methods were used to identify the LMD and validated against dual-Doppler derived vertical mass divergence fields for six cases with a variety of storm types. The best method for locating the LMD was determined to be the method that used a reflectivity texture technique to determine convective cores and a multi-layer echo identification to determine anvil locations. Although an improvement over previously published methods, the new methodology still produced unreliable results in certain regimes. The methodology worked best when applied to mature updrafts, as the anvil needs time to grow to a detectable size. Thus, radar reflectivity is found to be valuable in estimating the LMD, but storm maturity must also be considered for best results.

  17. Radar operation in a hostile electromagnetic environment

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-03-01

    Radar ISR does not always involve cooperative or even friendly targets. An adversary has numerous techniques available to him to counter the effectiveness of a radar ISR sensor. These generally fall under the banner of jamming, spoofing, or otherwise interfering with the EM signals required by the radar sensor. Consequently mitigation techniques are prudent to retain efficacy of the radar sensor. We discuss in general terms a number of mitigation techniques.

  18. Method and Implementation of High-speed Digital Sampling Technology Based on Impulse Radar Signal

    Directory of Open Access Journals (Sweden)

    Shen Shao-xiang

    2012-06-01

    Full Text Available A High-speed digital sampling technology suitable for periodical impulse radar signal is proposed in this paper. One bit high-speed quantize is constructed by differential comparator in FPGA. Time-interleaved digital sampling and buffer encoding are used to one bit stream based on the internal multi-phase clock of FPGA, to achieve sampling rate higher than 1 GHz. High speed digital sampling is realized by the accumulation of one bit sampling data with different comparison levels. An 8 bit, 1.6 GHz ADC based on the proposed method is realized on XC2V3000 Xilinx’s FPGA, which is successfully applied in GPR. The proposed method has the advantages of low cost and power consumption as compared with real sampling, and exhibits higher efficiency as compared with equivalent sampling.

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

    Institute of Scientific and Technical Information of China (English)

    Sun Bing; Zhou Yinqing; Chen Jie

    2011-01-01

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

  20. Passive Target Tracking in Non-cooperative Radar System Based on Particle Filtering

    Institute of Scientific and Technical Information of China (English)

    LI Shuo; TAO Ran

    2006-01-01

    We propose a target tracking method based on particle filtering(PF) to solve the nonlinear non-Gaussian target-tracking problem in the bistatic radar systems using external radiation sources. Traditional nonlinear state estimation method is extended Kalman filtering (EKF), which is to do the first level Taylor series extension. It will cause an inaccuracy or even a scatter estimation result on condition that there is either a highly nonlinear target or a large noise square-error. Besides, Kalman filtering is the optimal resolution under a Gaussian noise assumption, and is not suitable to the non-Gaussian condition. PF is a sort of statistic filtering based on Monte Carlo simulation that is using some random samples (particles) to simulate the posterior probability density of system random variables. This method can be used in any nonlinear random system. It can be concluded through simulation that PF can achieve higher accuracy than the traditional EKF.

  1. ESA CryoVEx 2011:Airborne field campaign with ASIRAS radar, EM induction sounder and laser scanner

    OpenAIRE

    Skourup, Henriette; Barletta, Valentina Roberta; Einarsson, Indriði; Forsberg, René; Haas, C.; V. Helm; S. Hendricks; Hvidegaard, Sine Munk; Sørensen, Louise Sandberg

    2013-01-01

    After the successful launch of CryoSat‐2 in April 2010, the first direct Arctic validation campaign of the satellite was carried out in the period April 15 ‐ May 8, 2011. This report describes the airborne part of the CryoSat Validation Experiment (CryoVEx) 2011, and includes;1) Data collected with the ESA airborne Ku‐band interferometric radar (ASIRAS), coincident airborne laser scanner (ALS) and vertical photography to acquire data over sea‐ and land ice along CryoSat‐2 ground tracks. The a...

  2. ESA CryoVEx 2012:Airborne field campaign with ASIRAS radar, EM induction sounder and laser scanner

    OpenAIRE

    Skourup, Henriette; Einarsson, Indriði; Forsberg, René; Haas, C.; Helms, V.; Hvidegaard, Sine Munk; Nilsson, Johan; Olesen, Arne Vestergaard; Olesen, Adolfientje Kasenda

    2012-01-01

    This report describes the airborne part of the Arctic CryoSat Validation Experiment (CryoVEx) 2012, which took place in the period March 25 – May 5, 2012, and includes; 1) Data collected with the ESA airborne Ku‐band interferometric radar (ASIRAS), coincident airborne laser scanner (ALS) and vertical photography to acquire data over sea‐ and land ice along CryoSat‐2 ground tracks. The airborne campaign was coordinated by DTU Space using the Norlandair Twin Otter (TF‐POF). 2) Sea ice thickness...

  3. Trilateration-based localization algorithm for ADS-B radar systems

    Science.gov (United States)

    Huang, Ming-Shih

    Rapidly increasing growth and demand in various unmanned aerial vehicles (UAV) have pushed governmental regulation development and numerous technology research advances toward integrating unmanned and manned aircraft into the same civil airspace. Safety of other airspace users is the primary concern; thus, with the introduction of UAV into the National Airspace System (NAS), a key issue to overcome is the risk of a collision with manned aircraft. The challenge of UAV integration is global. As automatic dependent surveillance-broadcast (ADS-B) system has gained wide acceptance, additional exploitations of the radioed satellite-based information are topics of current interest. One such opportunity includes the augmentation of the communication ADS-B signal with a random bi-phase modulation for concurrent use as a radar signal for detecting other aircraft in the vicinity. This dissertation provides detailed discussion about the ADS-B radar system, as well as the formulation and analysis of a suitable non-cooperative multi-target tracking method for the ADS-B radar system using radar ranging techniques and particle filter algorithms. In order to deal with specific challenges faced by the ADS-B radar system, several estimation algorithms are studied. Trilateration-based localization algorithms are proposed due to their easy implementation and their ability to work with coherent signal sources. The centroid of three most closely spaced intersections of constant-range loci is conventionally used as trilateration estimate without rigorous justification. In this dissertation, we address the quality of trilateration intersections through range scaling factors. A number of well-known triangle centers, including centroid, incenter, Lemoine point (LP), and Fermat point (FP), are discussed in detail. To the author's best knowledge, LP was never associated with trilateration techniques. According our study, LP is proposed as the best trilateration estimator thanks to the

  4. Improvement of Radar Quantitative Precipitation Estimation Based on Real-Time Adjustments to Z-R Relationships and Inverse Distance Weighting Correction Schemes

    Institute of Scientific and Technical Information of China (English)

    WANG Gaili; LIU Liping; DING Yuanyuan

    2012-01-01

    The errors in radar quantitative precipitation estimations consist not only of systematic biases caused by random noises but also spatially nonuniform biases in radar rainfall at individual rain-gauge stations.In this study,a real-time adjustment to the radar reflectivity-rainfall rates (Z R) relationship scheme and the gauge-corrected,radar-based,estimation scheme with inverse distance weighting interpolation was developed.Based on the characteristics of the two schemes,the two-step correction technique of radar quantitative precipitation estimation is proposed.To minimize the errors between radar quantitative precipitation estimations and rain gauge observations,a real-time adjustnent to the Z-R relationship scheme is used to remove systematic bias on the time-domain.The gauge-corrected,radar-based,estination scheme is then used to eliminate non-uniform errors in space.Based on radar data and rain gauge observations near the Huaihe River,the two-step correction technique was evaluated using two heavy-precipitation events.The results show that the proposed scheme improved not only in the underestination of rainfall but also reduced the root-mean-square error and the mean relative error of radar-rain gauge pairs.

  5. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

    OpenAIRE

    Xinpeng Zhou; Guohua Wei; Siliang Wu; Dawei Wang

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after transla...

  6. MetaSensing's FastGBSAR: ground based radar for deformation monitoring

    Science.gov (United States)

    Rödelsperger, Sabine; Meta, Adriano

    2014-10-01

    The continuous monitoring of ground deformation and structural movement has become an important task in engineering. MetaSensing introduces a novel sensor system, the Fast Ground Based Synthetic Aperture Radar (FastGBSAR), based on innovative technologies that have already been successfully applied to airborne SAR applications. The FastGBSAR allows the remote sensing of deformations of a slope or infrastructure from up to a distance of 4 km. The FastGBSAR can be setup in two different configurations: in Real Aperture Radar (RAR) mode it is capable of accurately measuring displacements along a linear range profile, ideal for monitoring vibrations of structures like bridges and towers (displacement accuracy up to 0.01 mm). Modal parameters can be determined within half an hour. Alternatively, in Synthetic Aperture Radar (SAR) configuration it produces two-dimensional displacement images with an acquisition time of less than 5 seconds, ideal for monitoring areal structures like dams, landslides and open pit mines (displacement accuracy up to 0.1 mm). The MetaSensing FastGBSAR is the first ground based SAR instrument on the market able to produce two-dimensional deformation maps with this high acquisition rate. By that, deformation time series with a high temporal and spatial resolution can be generated, giving detailed information useful to determine the deformation mechanisms involved and eventually to predict an incoming failure. The system is fully portable and can be quickly installed on bedrock or a basement. The data acquisition and processing can be fully automated leading to a low effort in instrument operation and maintenance. Due to the short acquisition time of FastGBSAR, the coherence between two acquisitions is very high and the phase unwrapping is simplified enormously. This yields a high density of resolution cells with good quality and high reliability of the acquired deformations. The deformation maps can directly be used as input into an Early

  7. Polarization Characteristics Simulation of Airborne Weather Radar Rainfall Target Based on Numerical Weather Prediction

    OpenAIRE

    Liu Xia; Han Yanfei; Li Hai; Lu Xiaoguang; Wu Renbiao

    2016-01-01

    Meteorological target simulation using polarization information is the foundation of the theoretical research and design application of dual-polarization Doppler weather radar. Currently, the theoretical research of airborne dual-polarization weather radar is in the development stage. To provide high-fidelity simulation data required for airborne dual-polarization weather radar detection technology, in this study, a simulation method of the polarization characteristics of rainfall determined ...

  8. A compressive radar system with chaotic-based FM signals using the Bernoulli map

    Science.gov (United States)

    Ochoa, Hector A.; Teja Enugula, Charan

    2013-05-01

    Matched filters are used in radar systems to identify echo signals embedded in noise. They allow us to extract range and Doppler information about the target from the reflected signal. In high frequency radars, matched filters make the system expensive and complex. For that reason, the radar research community is looking at techniques like compressive sensing or compressive sampling to eliminate the use of matched filters and high frequency analog-to-digital converters. In this work, compressive sensing is proposed as a method to increase the resolution and eliminate the use of matched filters in chaotic radars. Two basic scenarios are considered, one for stationary targets and one for non-stationary targets. For the stationary targets, the radar scene was a one dimensional vector, in which each element from the vector represents a target position. For the non-stationary targets, the radar scene was a two dimensional matrix, in which one direction of the matrix represents the target's range, and the other direction represents the target's velocity. Using optimization techniques, it was possible to recover both radar scenes from an under sampled echo signal. The reconstructed scenes were compared against a traditional matched filter system. In both cases, the matched filter was capable of recovering the radar scene. However, there was a considerable amount of artifacts introduced by the matched filter that made target identification a daunting task. On the other hand, using compressive sensing it was possible to recover both radar scenes perfectly, even when the echo signal was under sampled.

  9. Development of 101 Gene-based Single Nucleotide Polymorphism Markers in Sea Cucumber, <em>Apostichopus japonicusem>>

    Directory of Open Access Journals (Sweden)

    Wei Lu

    2012-06-01

    Full Text Available Single nucleotide polymorphisms (SNPs are currently the marker of choice in a variety of genetic studies. Using the high resolution melting (HRM genotyping approach, 101 gene-based SNP markers were developed for <em>Apostichopus japonicusem>, a sea cucumber species with economic significance for the aquaculture industry in East Asian countries. HRM analysis revealed that all the loci showed polymorphisms when evaluated using 40 <em>A. japonicusem> individuals collected from a natural population. The minor allele frequency ranged from 0.035 to 0.489. The observed and expected heterozygosities ranged from 0.050 to 0.833 and 0.073 to 0.907, respectively. Thirteen loci were found to depart significantly from Hardy–Weinberg equilibrium (HWE after Bonferroni corrections. Significant linkage disequilibrium (LD was detected in one pair of markers. These SNP markers are expected to be useful for future quantitative trait loci (QTL analysis, and to facilitate marker-assisted selection (MAS in <em>A. japonicusem>.

  10. Algoritmos de previsión a corto plazo en base a radar meteorológico

    OpenAIRE

    Campeny Mora, Mercè

    2008-01-01

    Las consecuencias de las inundaciones suelen ser devastadoras. Los sistemas de protección tradicionales se complementan cada vez más con sistemas de prevención y alerta de inundaciones. En este sentido, el radar meteorológico y los algoritmos de previsión adquieren una importancia clave. El objetivo de la tesina es la mejora de los algoritmos de previsión en base a radar meteorológico a partir del estudio de distintos factores que intervienen.

  11. The design of laser radar data acquisition system based on LabVIEW

    Science.gov (United States)

    Han, Dalong; Han, Shaokun; Cao, Jingya; Xia, Wenze; Wang, Liang

    2015-08-01

    Lidar has been widely used in areas of ranging and imaging. To be able to perform real-time control of the entire system, this article designed a lidar data acquisition system based on LabVIEW and the PC system allows real-time display for data acquired by lidar system. Through the serial port, the PC system can adjust part of the laser radar system parameters, such as frequency, APD (Avalanche Photo Diode) bias, the echo threshold, etc in real-time. In this way, we achieve the instruction communication between the PC system and the lidar. In addition, the PC system can also acquire data from the lidar through the Ethernet. Through the practical test, the PC system can successfully acquire and display the echo signal measured by lidar system in real-time, and function of parameter adjustment is also very sensitive.

  12. Nanostructured composites based on carbon nanotubes and epoxy resin for use as radar absorbing materials

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Valdirene Aparecida [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil); Folgueras, Luiza de Castro; Candido, Geraldo Mauricio; Paula, Adriano Luiz de; Rezende, Mirabel Cerqueira, E-mail: mirabelmcr@iae.cta.br [Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil). Div. de Materiais; Costa, Michelle Leali [Universidade Estadual Paulista Julio de Mesquita Filho (DMT/UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia

    2013-07-01

    Nanostructured polymer composites have opened up new perspectives for multifunctional materials. In particular, carbon nanotubes (CNTs) present potential applications in order to improve mechanical and electrical performance in composites with aerospace application. The combination of epoxy resin with multi walled carbon nanotubes results in a new functional material with enhanced electromagnetic properties. The objective of this work was the processing of radar absorbing materials based on formulations containing different quantities of carbon nanotubes in an epoxy resin matrix. To reach this objective the adequate concentration of CNTs in the resin matrix was determined. The processed structures were characterized by scanning electron microscopy, rheology, thermal and reflectivity in the frequency range of 8.2 to 12.4 GHz analyses. The microwave attenuation was up to 99.7%, using only 0.5% (w/w) of CNT, showing that these materials present advantages in performance associated with low additive concentrations (author)

  13. Root-MUSIC Based Angle Estimation for MIMO Radar with Unknown Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Jianfeng Li

    2014-01-01

    Full Text Available Direction of arrival (DOA estimation problem for multiple-input multiple-output (MIMO radar with unknown mutual coupling is studied, and an algorithm for the DOA estimation based on root multiple signal classification (MUSIC is proposed. Firstly, according to the Toeplitz structure of the mutual coupling matrix, output data of some specified sensors are selected to eliminate the influence of the mutual coupling. Then the reduced-dimension transformation is applied to make the computation burden lower as well as obtain a Vandermonde structure of the direction matrix. Finally, Root-MUSIC can be adopted for the angle estimation. The angle estimation performance of the proposed algorithm is better than that of estimation of signal parameters via rotational invariance techniques (ESPRIT-like algorithm and MUSIC-like algorithm. Furthermore, the proposed algorithm has lower complexity than them. The simulation results verify the effectiveness of the algorithm, and the theoretical estimation error of the algorithm is also derived.

  14. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  15. Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations

    Science.gov (United States)

    Bolen, Steve; Chandrasekar, V.

    2002-01-01

    Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for

  16. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  17. Validation of satellite OPEMW precipitation product with ground-based weather radar and rain gauge networks

    Directory of Open Access Journals (Sweden)

    D. Cimini

    2013-05-01

    Full Text Available The Precipitation Estimation at Microwave Frequencies (PEMW algorithm was developed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy (IMAA-CNR for inferring surface rain intensity (sri from satellite passive microwave observations in the range from 89 to 190 GHz. The operational version of PEMW (OPEMW has been running continuously at IMAA-CNR for two years, producing sri estimates feeding an operational hydrological model for forecasting flood alerts. This paper presents the validation of OPEMW against simultaneous ground-based observations obtained by a network of 20 weather radars and a network of more than 3000 rain gauges distributed over the Italian peninsula and main islands. The validation effort uses a data set spanning a one-year period (July 2011–June 2012. The effort evaluates dichotomous and continuous scores for the assessment of rain detection and quantitative estimate, respectively, investigating both spatial and temporal features. The analysis demonstrates 98% accuracy in correctly identifying rainy and non-rainy areas, and it quantifies the increased ability (with respect to random chance to detect rainy and non-rainy areas (0.42–0.45 Heidke skill score or rainy areas only (0.27–0.29 equitable threat score. Performances are better than average during summer, fall, and spring, while worse than average in the winter season. The spatial-temporal analysis does not show seasonal dependence except for larger mean absolute difference over the Alps and northern Apennines during winter, attributable to residual effect of snow cover. A binned analysis in the 0–15 mm h−1 range suggests that OPEMW tends to slightly overestimate sri values below 6–7 mm h−1, and to underestimate sri above those values. Depending upon the ground reference (either rain gauges or weather radars, the mean difference is 0.8–2.8 mm h−1, with a standard deviation within 2.6–3.1 mm h−1 and

  18. Effect of spatial resolution of radar-based inundation maps on the calibration of a spatial inundation model

    Science.gov (United States)

    Gobeyn, Sacha; Vernieuwe, Hilde; De Baets, Bernard; Bates, Paul; Verhoest Niko E., C.

    2013-04-01

    With advances in both flood mapping with satellite radar and computational science, the use of real-time spatial flood data holds the potential to support decision making during flood events. With recent improvements in satellite radar technology, current and future radar images are/will be delivered with higher spatial resolution. It is expected that these higher resolutions should improve the accuracy of the calibration and the prediction through data assimilation as more detailed information is available. However, these finer resolution data will result in an increased computational cost. Still, radar data of coarser resolution will remain available, and the question may then arise whether the calibration of a 2D-hydraulic model is significantly influenced by the resolution of the remotely-sensed inundation map. In order to answer this question, the raster-based inundation model, LISFLOOD-FP (Bates et al., 2000) is calibrated using a high resolution synthetic aperture radar image (ERS-2 SAR) of a flood event of the river Dee, Wales, in December 2006. Different radar resolutions are simulated through coarsening this image to different resolutions and retrieving the flood extent maps for the different resolutions. These flood maps are then used for calibrating the hydraulic model using the generalized likelihood uncertainty estimation (GLUE) framework presented by Aronica et al. (2002) as well as alternative calibration methods (e.g. Particle Swarm Optimization, PSO) to assess the possible impact of spatial resolution of the observed flood extent on the floodplain and channel Manning coefficient. Furthermore, the sensitivity of the calibration surface to error sources in radar measurement is evaluated by applying different magnitudes of noise to the radar image. References Aronica, G., Bates, P. D. and Horritt, M. S. (2002). Assessing the uncertainty in distributed model predictions using observed binary pattern information within GLUE. Hydrological Processes, 16

  19. Avalanche Debris Detection Using Satellite- and Drone Based Radar and Optical Remote Sensing

    Science.gov (United States)

    Eckerstorfer, M.; Malnes, E.; Vickers, H.; Solbø, S. A.; Tøllefsen, A.

    2014-12-01

    The mountainous fjord landscape in the county of Troms, around its capital Tromsø in Northern Norway is prone to high avalanche activity during the snow season. Large avalanches pose a hazard to infrastructure, such as buildings and roads, located between the steep mountainsides and the fjords. A prolonged cold spell during January and February 2014 was followed by rapid new-snow loading during March 2014, inducing a significant avalanche cycle with many spontaneous, size D4 avalanches that affected major transport veins. During and shortly after the avalanche cycle of March 2014, we obtained 11 Radarsat-2 Ultrafine mode scenes, chosen according to reported avalanche activity. We further collected four Radarsat-2 ScanSAR mode scenes and two Landsat-8 scenes covering the entire county of Troms. For one particular avalanche, we obtained a drone-based orthophoto, from which a DEM of the avalanche debris surface was derived, using structure-from-motion photogrammetry. This enabled us to calculate the debris volume accurately. We detected avalanche debris in the radar images visually, by applying two detection algorithms that make use of the increased backscatter in avalanche debris. This backscatter increase is a product of increased snow water equivalent and surface roughness, roughly of the order of 3 dB. In addition, we applied a multi-temporal approach by repeatedly detecting avalanche debris at different acquisition times, as well as a multi-sensor approach, covering similar areas with different sensors. This multi-temporal and multi-sensor approach enabled us to map the spatial extent and magnitude of the March 2014 avalanche cycle in the county Troms. With ESA's Sentinel-1 satellite, providing high-resolution, large swath radar images with a short repeat cycle, a complete avalanche record for a forecasting region could become feasible. In this first test season, we detected more than 550 avalanches that were released during a one-month period over an area of

  20. An intercomparison of radar-based liquid cloud microphysics retrievals and implications for model evaluation studies

    Directory of Open Access Journals (Sweden)

    D. Huang

    2012-06-01

    Full Text Available This paper presents a statistical comparison of three cloud retrieval products of the Atmospheric Radiation Measurement (ARM program at the Southern Great Plains (SGP site from 1998 to 2006: MICROBASE, University of Utah (UU, and University of North Dakota (UND products. The probability density functions of the various cloud liquid water content (LWC retrievals appear to be consistent with each other. While the mean MICROBASE and UU cloud LWC retrievals agree well in the middle of cloud, the discrepancy increases to about 0.03 gm−3 at cloud top and cloud base. Alarmingly large differences are found in the droplet effective radius (re retrievals. The mean MICROBASE re is more than 6 μm lower than the UU re, whereas the discrepancy is reduced to within 1 μm if columns containing raining and/or mixed-phase layers are excluded from the comparison. A suite of stratified comparisons and retrieval experiments reveal that the LWC difference stems primarily from rain contamination, partitioning of total liquid later path (LWP into warm and supercooled liquid, and the input cloud mask and LWP. The large discrepancy among the re retrievals is mainly due to rain contamination and the presence of mixed-phase layers. Since rain or ice particles are likely to dominate radar backscattering over cloud droplets, the large discrepancy found in this paper can be thought of as a physical limitation of single-frequency radar approaches. It is therefore suggested that data users should use the retrievals with caution when rain and/or mixed-phase layers are present in the column.

  1. Radar Chart

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Radar Chart collection is an archived product of summarized radar data. The geographic coverage is the 48 contiguous states of the United States. These hourly...

  2. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2001-01-01

    This book gives an introduction to the possibilities of radar technology based on active array antennas, giving examples of modern practical systems. There are many valuable lessons presented for designers of future high standard multifunction radar systems for military and civil applications. The book will appeal to graduate level engineers, researchers, and managers in the field of radar, aviation and space technology.

  3. The potential of radar-based ensemble forecasts for flash-flood early warning in the southern Swiss Alps

    Directory of Open Access Journals (Sweden)

    K. Liechti

    2013-10-01

    Full Text Available This study explores the limits of radar-based forecasting for hydrological runoff prediction. Two novel radar-based ensemble forecasting chains for flash-flood early warning are investigated in three catchments in the southern Swiss Alps and set in relation to deterministic discharge forecasts for the same catchments. The first radar-based ensemble forecasting chain is driven by NORA (Nowcasting of Orographic Rainfall by means of Analogues, an analogue-based heuristic nowcasting system to predict orographic rainfall for the following eight hours. The second ensemble forecasting system evaluated is REAL-C2, where the numerical weather prediction COSMO-2 is initialised with 25 different initial conditions derived from a four-day nowcast with the radar ensemble REAL. Additionally, three deterministic forecasting chains were analysed. The performance of these five flash-flood forecasting systems was analysed for 1389 h between June 2007 and December 2010 for which NORA forecasts were issued, due to the presence of orographic forcing. A clear preference was found for the ensemble approach. Discharge forecasts perform better when forced by NORA and REAL-C2 rather then by deterministic weather radar data. Moreover, it was observed that using an ensemble of initial conditions at the forecast initialisation, as in REAL-C2, significantly improved the forecast skill. These forecasts also perform better then forecasts forced by ensemble rainfall forecasts (NORA initialised form a single initial condition of the hydrological model. Thus the best results were obtained with the REAL-C2 forecasting chain. However, for regions where REAL cannot be produced, NORA might be an option for forecasting events triggered by orographic precipitation.

  4. A Semiautomated Multilayer Picking Algorithm for Ice-sheet Radar Echograms Applied to Ground-Based Near-Surface Data

    Science.gov (United States)

    Onana, Vincent De Paul; Koenig, Lora Suzanne; Ruth, Julia; Studinger, Michael; Harbeck, Jeremy P.

    2014-01-01

    Snow accumulation over an ice sheet is the sole mass input, making it a primary measurement for understanding the past, present, and future mass balance. Near-surface frequency-modulated continuous-wave (FMCW) radars image isochronous firn layers recording accumulation histories. The Semiautomated Multilayer Picking Algorithm (SAMPA) was designed and developed to trace annual accumulation layers in polar firn from both airborne and ground-based radars. The SAMPA algorithm is based on the Radon transform (RT) computed by blocks and angular orientations over a radar echogram. For each echogram's block, the RT maps firn segmented-layer features into peaks, which are picked using amplitude and width threshold parameters of peaks. A backward RT is then computed for each corresponding block, mapping the peaks back into picked segmented-layers. The segmented layers are then connected and smoothed to achieve a final layer pick across the echogram. Once input parameters are trained, SAMPA operates autonomously and can process hundreds of kilometers of radar data picking more than 40 layers. SAMPA final pick results and layer numbering still require a cursory manual adjustment to correct noncontinuous picks, which are likely not annual, and to correct for inconsistency in layer numbering. Despite the manual effort to train and check SAMPA results, it is an efficient tool for picking multiple accumulation layers in polar firn, reducing time over manual digitizing efforts. The trackability of good detected layers is greater than 90%.

  5. An Aircraft And Radar Based Analysis Of Cloud And Precipitation Microphysics In Mid-Latitude Continental Clouds

    Science.gov (United States)

    Mishra, S.; Kumjian, M.; Bansemer, A.; Giangrande, S. E.; Ryzhkov, A.; Toto, T.

    2014-12-01

    An observational analysis of precipitation microphysics was conducted using data obtained during the Midlatitude Continental Convective Clouds Experiment (MC3E) that took place around the Atmospheric Radiation Measurement (ARM) site in Lamont, Oklahoma from April 22- June 6, 2011. MC3E was a collaborative campaign led by the National Aeronautic and Space Administration's (NASA's) Global Precipitation Measurement (GPM) mission and the U.S. Department of Energy ARM program. MC3E provided a unique opportunity to compare in-situ data from aircraft based microphysical probes with data from polarimetric radars in the radar bright band region or melting layer. One of the primary objectives of this study was to understand how riming and aggregation affect polarimetric signatures. In depth case study analysis of cloud and precipitation microphysics was performed for two specific cases, April 27th, 2011 (A27) and May 20th, 2011 (M20). Both these cases provided coincident aircraft and radar data in extensive stratiform cloud regions. Measurements from the University of North Dakota (UND) Citation aircraft and polarimetric data from the ARM CSAPR data reveal interesting details of cloud scale processes. Observations based on data from cloud probes (2DC, CIP and HVPS) along with in-situ observations of environmental variables provide remarkable details of particle growth and cloud dynamics for both case studies. For the A27 case study, UND aircraft measurements from two successive spiral profiles through the stratiform cloud region showed a transition from a riming dominated region to an aggregation dominated region. This is supported by polarimetric data from the C-Band ARM Precipitation Radar (CSAPR ). An extensive region of trailing stratiform precipitation was sampled in the M20 case study, where the aggregation, melting, and evaporation processes were measured in detail with the in-situ microphysical instruments. Latest findings from MC3E based on this combined aircraft

  6. Point cloud uncertainty analysis for laser radar measurement system based on error ellipsoid model

    Science.gov (United States)

    Zhengchun, Du; Zhaoyong, Wu; Jianguo, Yang

    2016-04-01

    Three-dimensional laser scanning has become an increasingly popular measurement method in industrial fields as it provides a non-contact means of measuring large objects, whereas the conventional methods are contact-based. However, the data acquisition process is subject to many interference factors, which inevitably cause errors. Therefore, it is necessary to precisely evaluate the accuracy of the measurement results. In this study, an error-ellipsoid-based uncertainty model was applied to 3D laser radar measurement system (LRMS) data. First, a spatial point uncertainty distribution map was constructed according to the error ellipsoid attributes. The single-point uncertainty ellipsoid model was then extended to point-point, point-plane, and plane-plane situations, and the corresponding distance uncertainty models were derived. Finally, verification experiments were performed by using an LRMS to measure the height of a cubic object, and the measurement accuracies were evaluated. The results show that the plane-plane distance uncertainties determined based on the ellipsoid model are comparable to those obtained by actual distance measurements. Thus, this model offers solid theoretical support to enable further LRMS measurement accuracy improvement.

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

    Science.gov (United States)

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

    2016-04-01

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

  8. Structural analysis of the central Columbia Plateau utilizing radar, digital topography, and magnetic data bases

    International Nuclear Information System (INIS)

    Interest in the Hanford site (Washington) as a nuclear production, power, and waste disposal site has led to generation of a vast quantity of geophysical and remote sensing data sets of the central Columbia Plateau. To data, these various studies, including at least 13 independent magnetic linear and image lineament studies, have not been adequately correlated. Therefore, these studies provide a unique opportunity to compare and contrast the viability of the different geophysical and remote sensing techniques. The geology of the central Columbia Plateau is characterized by subdued topography and limited outcrop, with most of the exposure concentrated in localized folded/faulted mountains (the Yakima folds) and along river canyons. In order to efficiently compare lineament data bases, we have written an automated computer routine that correlated lineaments that are within a user specified distance of each other. The angle between their trends has to be less than an input maximum separation angle. If more than two lineament maps exist for the area, the analyst may also specify the minimum number of times each structure must be seen. The lineament correlation routine was applied to data bases of all aeromagnetic linears as well as lineaments seen on radar and a digital elevation model DEM image. Geologic structures align with a set of three-dimensional planar structures identified with our Geologic Spatial Analysis (GSA) system. The GSA analysis is based upon computer automated detection of valley bottoms as defined by a DEM

  9. 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.

  10. Design of a Radar Signal Simulator Based on Virtex-Ⅱ Series FPGA

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A simulation method to simulate the pseudorandom code P.M PP radar's echo signal is proposed that makes use of the pre-generated Doppler simulation data, according to the relative movement parameter of the radar and the target. It resolves the problem of the high precision distance simulation and the high speed digital shift phase. At the same time, the radar dynamic digital video frequency target signal simulator is designed. Simulation results of the critical unit and the output waveform are given. The result of the test satisfies the system's request.

  11. Radar based Ground Level Reconstruction Utilizing a Hypocycloid Antenna Positioning System

    Science.gov (United States)

    Baer, Christoph; Musch, Thomas

    2015-01-01

    In this contribution we introduce a novel radar positioning system. It makes use of a mathematical curve, called hypocycloid, for a slanting movement of the radar antenna. By means of a planetary gear, a ball, and a universal joint as well as a stepping motor, a two dimensional positioning is provided by a uniaxial drive shaft exclusively. The fundamental position calculation and different signal processing algorithms are presented. By means of an 80 GHz FMCW radar system we performed several measurements on objects with discrete heights as well as on objects with continuous surfaces. The results of these investigations are essential part of this contribution and are discussed in detail.

  12. Identification of Mine-Shaped Objects based on an Efficient Phase Stepped-Frequency Radar Approach

    DEFF Research Database (Denmark)

    Sørensen, Helge Bjarup Dissing; Jakobsen, Kaj Bjarne; Nymann, Ole

    A computational efficient approach to identify very small mine-shaped plastic objects, e.g. M56 Anti-Personnel (AP) mines buried in the ground, is presented. The size of the objects equals the smallest AP-mines in use today, i.e., the most difficult mines to detect with respect to humanitarian mine...... clearance. Our approach consists of three stages, the phase stepped-frequency radar method, generation of a quarternary image and template crosscorrelation. The phase stepped-frequency radar method belongs to the class of stepped-frequency radar methods. In a two-dimensional mesh-grid above the ground a...

  13. Radar-based full-body screening of passengers with constant motion

    Science.gov (United States)

    Hantscher, S.; Schlenther, B.; Lang, S.; Hägelen, M.; Essen, H.; Tessmann, A.

    2012-06-01

    This paper presents a rotating W band radar performing a full body scan of persons which are moving with constant speed below the radar. The radar consists of a FMCW module sweeping the frequency between 96 GHz and 99 GHz by a varactor tuned VCO. The transmit and receive modules are fabricated in split-block technology using 100 nm metamorphic HEMT MMICs. The used 4 channel receiver operates between 84 GHz and 104 GHz and an average noise figure of 3.5 dB. Polarimetric measurements are carried out for the detection of oblong objects such as explosive tubes.

  14. Intelligent radar data processing

    Science.gov (United States)

    Holzbaur, Ulrich D.

    The application of artificial intelligence principles to the processing of radar signals is considered theoretically. The main capabilities required are learning and adaptation in a changing environment, processing and modeling information (especially dynamics and uncertainty), and decision-making based on all available information (taking its reliability into account). For the application to combat-aircraft radar systems, the tasks include the combination of data from different types of sensors, reacting to electronic counter-countermeasures, evaluation of how much data should be acquired (energy and radiation management), control of the radar, tracking, and identification. Also discussed are related uses such as monitoring the avionics systems, supporting pilot decisions with respect to the radar system, and general applications in radar-system R&D.

  15. Radar Fundamentals, Presentation

    OpenAIRE

    Jenn, David

    2008-01-01

    Topics include: introduction, radar functions, antennas basics, radar range equation, system parameters, electromagnetic waves, scattering mechanisms, radar cross section and stealth, and sample radar systems.

  16. Sparsity-based moving target localization using multiple dual-frequency radars under phase errors

    Science.gov (United States)

    Al Kadry, Khodour; Ahmad, Fauzia; Amin, Moeness G.

    2015-05-01

    In this paper, we consider moving target localization in urban environments using a multiplicity of dual-frequency radars. Dual-frequency radars offer the benefit of reduced complexity and fast computation time, thereby permitting real-time indoor target localization and tracking. The multiple radar units are deployed in a distributed system configuration, which provides robustness against target obscuration. We develop the dual-frequency signal model for the distributed radar system under phase errors and employ a joint sparse scene reconstruction and phase error correction technique to provide accurate target location and velocity estimates. Simulation results are provided that validate the performance of the proposed scheme under both full and reduced data volumes.

  17. Net Energy, CO2 Emission and Land-Based Cost-Benefit Analyses of <em>Jatropha> em>Biodiesel: A Case Study of the Panzhihua Region of Sichuan Province in China

    Directory of Open Access Journals (Sweden)

    Xiangzheng Deng

    2012-06-01

    Full Text Available Bioenergy is currently regarded as a renewable energy source with a high growth potential. Forest-based biodiesel, with the significant advantage of not competing with grain production on cultivated land, has been considered as a promising substitute for diesel fuel by many countries, including China. Consequently, extracting biodiesel from <em>Jatropha> curcasem> has become a growing industry. However, many key issues related to the development of this industry are still not fully resolved and the prospects for this industry are complicated. The aim of this paper is to evaluate the net energy, CO2 emission, and cost efficiency of <em>Jatropha> biodiesel as a substitute fuel in China to help resolve some of the key issues by studying data from this region of China that is well suited to growing <em>Jatropha>. Our results show that: (1 <em>Jatropha> biodiesel is preferable for global warming mitigation over diesel fuel in terms of the carbon sink during <em>Jatropha> tree growth. (2 The net energy yield of <em>Jatropha> biodiesel is much lower than that of fossil fuel, induced by the high energy consumption during <em>Jatropha> plantation establishment and the conversion from seed oil to diesel fuel step. Therefore, the energy efficiencies of the production of <em>Jatropha> and its conversion to biodiesel need to be improved. (3 Due to current low profit and high risk in the study area, farmers have little incentive to continue or increase <em>Jatropha> production. (4 It is necessary to provide more subsidies and preferential policies for <em>Jatropha> plantations if this industry is to grow. It is also necessary for local government to set realistic objectives and make rational plans to choose proper sites for <em>Jatropha> biodiesel development and the work reported here should assist that effort. Future research focused on breading high-yield varieties, development of efficient field

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

    Institute of Scientific and Technical Information of China (English)

    苏伍各; 王宏强; 阳召成

    2014-01-01

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

  19. 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.

  20. Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

    OpenAIRE

    Huang Hao; Pan Minghai; Lu Zhijun

    2015-01-01

    Hardware-in-the-loop (HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of...

  1. LFM Radar Convolution Jamming Suppression Based on Oblique Projection in FrFT Domain

    OpenAIRE

    Wang Jun; Ping Fulong; Zhao Yuan; Tang Bin

    2016-01-01

    Convolution false-targets jamming against LFM fire-control radars generates range and velocity false targets which are coherent with target echo, which increases the difficulty of jamming detection and suppression and makes the victim radar system lost the track of real target. To combat against this type of jamming, the uncorrelated characteristic between the jamming and echo in FRFT domain is discussed firstly. Thus, an oblique projection operator which is capable of suppress convolution fa...

  2. Estimating Target Heights Based on the Earth Curvature Model and Micromultipath Effect in Skywave OTH Radar

    OpenAIRE

    Hou Chengyu; Wang Yuxin; Chen Jiawei

    2014-01-01

    Skywave over-the-horizon (OTH) radar systems have important long-range strategic warning values. They exploit skywave propagation reflection of high frequency signals from the ionosphere, which provides the ultra-long-range surveillance capabilities to detect and track maneuvering targets. Current OTH radar systems are capable of localizing targets in range and azimuth but are unable to achieve reliable instantaneous altitude estimation. Most existing height measurement methods of skywave OTH...

  3. Lens-based 77 GHZ MIMO radar for angular estimation in multitarget environments

    OpenAIRE

    Lutz, Steffen; Walter, Thomas; Weigel, Robert

    2014-01-01

    The demanding tasks for automotive radar systems in multitarget scenarios require an increased target separation performance and new sensor concepts. In this contribution, a highly integrated 77 GHz time domain multiplex (TDM) MIMO radar is presented. The sensor is feasible for advanced direction of arrival (DOA) estimation in azimuth and elevation. For efficient and high-quality measurements a fractional-n phased locked loop (PLL) with integrated waveform generator, enabling chirp and freque...

  4. Automatic recognition of radar signals based on time-frequency image shape character

    Directory of Open Access Journals (Sweden)

    Jian-dong zhu

    2013-05-01

    Full Text Available Radar signal recognition is one of the key technologies of modern electronic surveillance systems. Time-frequency image provides a new way for recognizing the radar signal. In this paper, a series of image processing methods containing image enhancement, image threshold binarization and mathematical morphology is utilized to extract the shape character of smoothed pseudo wigner-ville time-frequency distribution of radar signal. And then the identification of radar signal is realized by the character. Simulation results of eight kinds of typical radar signal demonstrate that when signal noise ratio (SNR is greater than -3 dB, the Legendre moments shape character of the time-frequency image is very stable. Moreover, the recognition rate by the character is more than 90 per cent except for the FRANK code signal when SNR > -3 dB. Test also show that the proposed method can effectively recognize radar signal with less character dimension through compared with exitsing algorithms.Defence Science Journal, 2013, 63(3, pp.308-314, DOI:http://dx.doi.org/10.14429/dsj.63.2404

  5. Temporal Stability of Surface Roughness Effects on Radar Based Soil Moisture Retrieval During the Corn Growth Cycle

    Science.gov (United States)

    Joseph, A.T.; Lang, R.; O'Neill, P.E.; van der Velde, R.; Gish, T.

    2008-01-01

    A representative soil surface roughness parameterization needed for the retrieval of soil moisture from active microwave satellite observation is difficult to obtain through either in-situ measurements or remote sensing-based inversion techniques. Typically, for the retrieval of soil moisture, temporal variations in surface roughness are assumed to be negligible. Although previous investigations have suggested that this assumption might be reasonable for natural vegetation covers (Moran et al. 2002, Thoma et al. 2006), insitu measurements over plowed agricultural fields (Callens et al. 2006) have shown that the soil surface roughness can change considerably over time. This paper reports on the temporal stability of surface roughness effects on radar observations and soil moisture retrieved from these radar observations collected once a week during a corn growth cycle (May 10th - October 2002). The data set employed was collected during the Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) field campaign covering this 2002 corn growth cycle and consists of dual-polarized (HH and VV) L-band (1.6 GHz) acquired at view angles of 15, 35, and 55 degrees. Cross-polarized L baud radar data were also collected as part of this experiment, but are not used in the analysis reported on here. After accounting for vegetation effects on radar observations, time-invariant optimum roughness parameters were determined using the Integral Equation Method (IEM) and radar observations acquired over bare soil and cropped conditions (the complete radar data set includes entire corn growth cycle). The optimum roughness parameters, soil moisture retrieval uncertainty, temporal distribution of retrieval errors and its relationship with the weather conditions (e.g. rainfall and wind speed) have been analyzed. It is shown that over the corn growth cycle, temporal roughness variations due to weathering by rain are responsible for almost 50% of soil moisture retrieval

  6. A coherent FM laser radar based system for remote metrology in ITER

    International Nuclear Information System (INIS)

    The plasma facing surfaces in ITER must be aligned to millimeter accuracy with respect to the magnetic flux surfaces to prevent impurity influx into the plasma and to avoid component damage. Checking of in-vessel component alignment during initial assembly, operation, and subsequent maintenance is anticipated. A fully remote metrology system is necessary, particularly since major remote operations such as shield blanket exchange and divertor cassette replacement are planned. The metrology system must be compatible with the ITER in-vessel environment of high gamma radiation, super-clean ultra-high-vacuum, and elevated temperature. A fast scanning rate is required since the plasma facing surface in ITER is very large. A coherent FM laser radar based metrology system, developed by Coleman Research Corporation, is being adopted to accomplish this task. Conceptually, this metrology system consists of a compact remotely deployed laser transceiver optics module, linked through fiber optics to the laser source and imaging units that are located outside the biological shield. Range measurements conducted on a variety of surfaces using the system have yielded sub-millimeter accuracy. Therefore, the technique will easily meet the precision requirement for the ITER application. Computer simulations have been carried out to determine the optimum number of units required for complete mapping of the plasma facing surfaces

  7. Convolutional neural network based sensor fusion for forward looking ground penetrating radar

    Science.gov (United States)

    Sakaguchi, Rayn; Crosskey, Miles; Chen, David; Walenz, Brett; Morton, Kenneth

    2016-05-01

    Forward looking ground penetrating radar (FLGPR) is an alternative buried threat sensing technology designed to offer additional standoff compared to downward looking GPR systems. Due to additional flexibility in antenna configurations, FLGPR systems can accommodate multiple sensor modalities on the same platform that can provide complimentary information. The different sensor modalities present challenges in both developing informative feature extraction methods, and fusing sensor information in order to obtain the best discrimination performance. This work uses convolutional neural networks in order to jointly learn features across two sensor modalities and fuse the information in order to distinguish between target and non-target regions. This joint optimization is possible by modifying the traditional image-based convolutional neural network configuration to extract data from multiple sources. The filters generated by this process create a learned feature extraction method that is optimized to provide the best discrimination performance when fused. This paper presents the results of applying convolutional neural networks and compares these results to the use of fusion performed with a linear classifier. This paper also compares performance between convolutional neural networks architectures to show the benefit of fusing the sensor information in different ways.

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    Zhu Yupeng

    2009-09-01

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

  10. Systematic investigations of intense convective precipitation events on European scale based on radar- and lightning-cell tracking

    Science.gov (United States)

    Tüchler, Lukas; Meyer, Vera

    2013-04-01

    The new radar-data and lightning-data based automatic cell identification, tracking and nowcasting tool A-TNT (Austrian Thunderstorm Nowcasting Tool), which has been developed at ZAMG, has been applied to investigate the appearance of thunderstorms at Europe scale. Based on the ec-TRAM-method [1], the algorithm identifies and monitors regions of intense precipitation and lightning activity separately by analyzing sequential two-dimensional intensity maps of radar precipitation rate or lightning densities, respectively. Each data source is processed by a stand-alone identification, tracking and nowcasting procedure. The two tracking results are combined to a "main" cell in a final step. This approach allows that the output derived from the two data sources complement each other giving a more comprehensive picture about the current storm situation. So it is possible to distinguish between pure precipitation cells and thunderstorms, to observe regions, where one data source is not or poorly available, and to compensate for occasional data failures. Consequently, the combined cell-tracks are expected to be more consistent and the cell-tracking more robust. Input data for radar-cell tracking on European Scale is the OPERA radar-composite, which is provided every 15 minutes on a 2 km x 2 km grid, indicating the location and intensity of precipitation over Europe. For the lightning-cell tracking, the lightning-detection data of the EUCLID network is mapped on the OPERA grid. Every five minutes, flash density maps with recorded strokes are created and analyzed. This study will present a detailed investigation of the quality of the identification and tracking results using radar and lightning data. The improvements concerning the robustness and reliability of the cell tracking achieved by combining both data sources will be shown. Analyses about cell tracks and selected storm parameters like frequency, longevity and area will give insight into occurrence, appearance and

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

    OpenAIRE

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

    2016-01-01

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

  12. Radar imaging

    OpenAIRE

    Borden, Brett; Cheney, Margaret

    2013-01-01

    The article of record as published may be found at http://dx.doi.org/1088/0266-5611/29/5/050301 Because of their ability to operate without regard to day, night or weather conditions, radar systems are ubiquitous in remote sensing operations and are used in a wide variety of commercial and military applications. High resolution radar imaging, however, is a remote sensing subcategory that requires raw radar data to be collected over an artificially extended aperture that is much...

  13. Radar seeker based autonomous navigation update system using topography feature matching techniques

    Science.gov (United States)

    Lerche, H. D.; Tumbreagel, F.

    1992-11-01

    The discussed navigation update system was designed for an unmanned platform with fire and forget capability. It meets the requirement due to fully autonomous operation. The system concept will be characterized by complementary use of the radar seeker for target identification as well as for navigation function. The system works in the navigation mode during preprogrammable phases where the primary target identification function is not active or in parallel processing. The dual function radar seeker system navigates the drone during the midcourse and terminal phases of the mission. Its high resolution due to range measurement and doppler beam sharpening in context with its radar reflectivity sensing capability are the basis for topography referenced navigation computation. The detected height jumps (coming from terrain elevation and cultural objects) and radar reflectivity features will be matched together with topography referenced features. The database comprises elevation data and selected radar reflectivity features that are robust against seasonal influences. The operational benefits of the discussed system are as follows: (1) the improved navigation performance with high probability of position fixing, even over flat terrain; (2) the operation within higher altitudes; and (3) bad weather capability. The developed software modules were verified with captive flight test data running in a hardware-in-the-loop simulation.

  14. EISCAT Svalbard radar

    Science.gov (United States)

    Lehtinen, Markku; Kangas, Jorma

    1992-02-01

    The main fields of interest of the Finnish scientists in EISCAT research are listed. Finnish interests in the Polar Cap Radar (PMR) and areas where the Finnish contribution could be important are addressed: radar techniques; sporadic E layers in the polar cap; atmospheric models; auroral studies in the polar cap; nonthermal plasmas in the F region; coordinated measurements with the Cluster satellites; studies of the ionospheric traveling; convection vortices; polar cap absorption; studies of lower atmosphere; educational program. A report on the design specification of an ionospheric and atmospheric radar facility based on the archipelago of Svalbard (Norway) is summarized.

  15. EM Structure Based and Vacuum Acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Colby, E.R.; /SLAC

    2005-09-27

    The importance of particle acceleration may be judged from the number of applications which require some sort of accelerated beam. In addition to accelerator-based high energy physics research, non-academic applications include medical imaging and treatment, structural biology by x-ray diffraction, pulse radiography, cargo inspection, material processing, food and medical instrument sterilization, and so on. Many of these applications are already well served by existing technologies and will profit only marginally from developments in accelerator technology. Other applications are poorly served, such as structural biology, which is conducted at synchrotron radiation facilities, and medical treatment using proton accelerators, the machines for which are rare because they are complex and costly. Developments in very compact, high brightness and high gradient accelerators will change how accelerators are used for such applications, and potentially enable new ones. Physical and technical issues governing structure-based and vacuum acceleration of charged particles are reviewed, with emphasis on practical aspects.

  16. The Simultaneous Interpolation of Target Radar Cross Section in Both the Spatial and Frequency Domains by Means of Legendre Wavelets Model-Based Parameter Estimation

    OpenAIRE

    Yongqiang Yang; Yunpeng Ma; Lifeng Wang

    2015-01-01

    The understanding of the target radar cross section (RCS) is significant for target identification and for radar designing and optimization. In this paper, a numerical algorithm for calculating target RCS is presented which is based on Legendre wavelet model-based parameter estimation (LW-MBPE). The Padé rational function fitting model applied for MBPE in the frequency domain is enhanced to include spatial dependence on the numerator and denominator coefficients. This allows the function to i...

  17. An operational weather radar-based Quantitative Precipitation Estimation and its application in catchment water resources modeling

    DEFF Research Database (Denmark)

    He, Xin; Vejen, Flemming; Stisen, Simon;

    2011-01-01

    The Danish Meteorological Institute operates a radar network consisting of five C-band Doppler radars. Quantitative precipitation estimation (QPE) using radar data is performed on a daily basis. Radar QPE is considered to have the potential to signifi cantly improve the spatial representation of ...

  18. Application of model-based spectral analysis to wind-profiler radar observations

    Directory of Open Access Journals (Sweden)

    E. Boyer

    Full Text Available A classical way to reduce a radar’s data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometeor echo. . . exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunder-storms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar’s data.

    Key words. Meteorology and atmospheric dynamics (tropical meteorology- Radio science (signal processing- General (techniques applicable in three or more fields

  19. Application of model-based spectral analysis to wind-profiler radar observations

    Science.gov (United States)

    Boyer, E.; Petitdidier, M.; Corneil, W.; Adnet, C.; Larzabal, P.

    2001-08-01

    A classical way to reduce a radar’s data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometeor echo. . . ) exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunder-storms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar’s data.

  20. Parameter estimation for rigid body after micro-Doppler removal based on L-statistics in the radar analysis

    Institute of Scientific and Technical Information of China (English)

    Yong Wang; Jian Kang

    2015-01-01

    In traditional inverse synthetic aperture radar (ISAR) imaging of moving targets with rotational parts, the micro-Doppler (m-D) effects caused by the rotational parts influence the quality of the radar images. Recently, L. Stankovic proposed an m-D removal method based on L-statistics, which has been proved effective and simple. The algorithm can extract the m-D effects according to different behaviors of signals induced by rotational parts and rigid bodies in time-frequency (T-F) domain. However, by removing m-D effects, some useful short time Fourier transform (STFT) samples of rigid bodies are also extracted, which induces the side lobe problem of rigid bodies. A parameter estimation method for rigid bodies after m-D removal is proposed, which can accurately re-cover rigid bodies and avoid the side lobe problem by only using m-D removal. Simulations are given to validate the effectiveness of the proposed method.

  1. Electromagnetic behavior of radar absorbing materials based on Ca hexaferrite modified with Co-Ti ions and doped with La

    Directory of Open Access Journals (Sweden)

    Valdirene Aparecida da Silva

    2009-06-01

    Full Text Available Radar Absorbing Materials (RAM are compounds that absorb incidental electromagnetic radiation in tuned frequencies and dissipate it as heat. Its preparation involves the adequate processing of polymeric matrices filled with compounds that act as radar absorbing centers in the microwave range. This work shows the electromagnetic evaluation of RAM based on CoTi and La doped Ca hexaferrite. Vibrating Sample Magnetization analyses show that ion substitution promoted low values for the parameters of saturation magnetization (123.65 Am2/kg and coercive field (0.07 T indicating ferrite softening. RAM samples obtained using different hexaferrite concentrations (40-80 per cent, w/w show variations in complex permeability and permittivity parameters and also in the performance of incidental radiation attenuation. Microwave attenuation values between 40 and 98 per cent were obtained.

  2. Quasi-Coherent Noise Jamming to LFM Radar Based on Pseudo-random Sequence Phase-modulation

    Directory of Open Access Journals (Sweden)

    N. Tai

    2015-12-01

    Full Text Available A novel quasi-coherent noise jamming method is proposed against linear frequency modulation (LFM signal and pulse compression radar. Based on the structure of digital radio frequency memory (DRFM, the jamming signal is acquired by the pseudo-random sequence phase-modulation of sampled radar signal. The characteristic of jamming signal in time domain and frequency domain is analyzed in detail. Results of ambiguity function indicate that the blanket jamming effect along the range direction will be formed when jamming signal passes through the matched filter. By flexible controlling the parameters of interrupted-sampling pulse and pseudo-random sequence, different covering distances and jamming effects will be achieved. When the jamming power is equivalent, this jamming obtains higher process gain compared with non-coherent jamming. The jamming signal enhances the detection threshold and the real target avoids being detected. Simulation results and circuit engineering implementation validate that the jamming signal covers real target effectively.

  3. Synergetic Optimization of Missile Shapes for Aerodynamic and Radar Cross-Section Performance Based on Multi- objective Evolutionary Algorithm

    Institute of Scientific and Technical Information of China (English)

    刘洪

    2004-01-01

    A multiple-objective evolutionary algorithm (MOEA) with a new Decision Making (DM) scheme for MOD of conceptual missile shapes was presented, which is contrived to determine suitable tradeoffs from Pareto optimal set using interactive preference articulation. There are two objective functions, to maximize ratio of lift to drag and to minimize radar cross-section (RCS) value. 3D computational electromagnetic solver was used to evaluate RCS, electromagnetic performance. 3D Navier-Stokes flow solver was adopted to evaluate aerodynamic performance. A flight mechanics solver was used to analyze the stability of the missile. Based on the MOEA, a synergetic optimization of missile shapes for aerodynamic and radar cross-section performance is completed. The results show that the proposed approach can be used in more complex optimization case of flight vehicles.

  4. LFM Radar Convolution Jamming Suppression Based on Oblique Projection in FrFT Domain

    Directory of Open Access Journals (Sweden)

    Wang Jun

    2016-01-01

    Full Text Available Convolution false-targets jamming against LFM fire-control radars generates range and velocity false targets which are coherent with target echo, which increases the difficulty of jamming detection and suppression and makes the victim radar system lost the track of real target. To combat against this type of jamming, the uncorrelated characteristic between the jamming and echo in FRFT domain is discussed firstly. Thus, an oblique projection operator which is capable of suppress convolution false-targets jamming is built. The simulation results showed the operator have little effect on the echo and proved the effectiveness of this method.

  5. Measurement data preprocessing in a radar-based system for monitoring of human movements

    International Nuclear Information System (INIS)

    The importance of research on new technologies that could be employed in care services for elderly people is highlighted. The need to examine the applicability of various sensor systems for non-invasive monitoring of the movements and vital bodily functions, such as heart beat or breathing rhythm, of elderly persons in their home environment is justified. An extensive overview of the literature concerning existing monitoring techniques is provided. A technological potential behind radar sensors is indicated. A new class of algorithms for preprocessing of measurement data from impulse radar sensors, when applied for elderly people monitoring, is proposed. Preliminary results of numerical experiments performed on those algorithms are demonstrated

  6. An Unbiased Unscented Transform Based Kalman Filter for 3D Radar

    Institute of Scientific and Technical Information of China (English)

    WANGGuohong; XIUJianjuan; HEYou

    2004-01-01

    As a derivative-free alternative to the Extended Kalman filter (EKF) in the framework of state estimation, the Unscented Kalman filter (UKF) has potential applications in nonlinear filtering. By noting the fact that the unscented transform is generally biased when converting the radar measurements from spherical coordinates into Cartesian coordinates, a new filtering algorithm for 3D radar, called Unbiased unscented Kalman filter (UUKF), is proposed. The new algorithm is validated by Monte Carlo simulation runs. Simulation results show that the UUKF is more effective than the UKF, EKF and the Converted measurement Kalman filter (CMKF).

  7. A New MCMC Sampling Based Segment Model for Radar Target Recognition

    OpenAIRE

    M. Hadavi; Radmard, M.; Nayebi, M. M.

    2015-01-01

    One of the main tools in radar target recognition is high resolution range profile (HRRP)‎. ‎However‎, ‎it is very sensitive to the aspect angle‎. ‎One solution to this problem is to assume the consecutive samples of HRRP identically independently distributed (IID) in small frames of aspect angles‎, ‎an assumption which is not true in reality‎. ‎However, b‎‎ased on this assumption‎, ‎some models have been developed to characterize the sequential information contained in the multi-aspect radar...

  8. GLUE Based Uncertainty Estimation of Urban Drainage Modeling Using Weather Radar Precipitation Estimates

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2011-01-01

    Distributed weather radar precipitation measurements are used as rainfall input for an urban drainage model, to simulate the runoff from a small catchment of Denmark. It is demonstrated how the Generalized Likelihood Uncertainty Estimation (GLUE) methodology can be implemented and used to estimate...... the uncertainty of the weather radar rainfall input. The main findings of this work, is that the input uncertainty propagate through the urban drainage model with significant effects on the model result. The GLUE methodology is in general a usable way to explore this uncertainty although; the exact width...

  9. Brief Communication: Contrast-stretching- and histogram-smoothness-based synthetic aperture radar image enhancement for flood map generation

    Science.gov (United States)

    Nazir, F.; Riaz, M. M.; Ghafoor, A.; Arif, F.

    2015-02-01

    Synthetic-aperture-radar-image-based flood map generation is usually a challenging task (due to degraded contrast). A three-step approach (based on adaptive histogram clipping, histogram remapping and smoothing) is proposed for generation of a more visualized flood map image. The pre- and post-flood images are adaptively histogram equalized. The hidden details in difference image are enhanced using contrast-based enhancement and histogram smoothing. A fast-ready flood map is then generated using equalized pre-, post- and difference images. Results (evaluated using different data sets) show significance of the proposed technique.

  10. Improving high-resolution quantitative precipitation estimation via fusion of multiple radar-based precipitation products

    Science.gov (United States)

    Rafieeinasab, Arezoo; Norouzi, Amir; Seo, Dong-Jun; Nelson, Brian

    2015-12-01

    For monitoring and prediction of water-related hazards in urban areas such as flash flooding, high-resolution hydrologic and hydraulic modeling is necessary. Because of large sensitivity and scale dependence of rainfall-runoff models to errors in quantitative precipitation estimates (QPE), it is very important that the accuracy of QPE be improved in high-resolution hydrologic modeling to the greatest extent possible. With the availability of multiple radar-based precipitation products in many areas, one may now consider fusing them to produce more accurate high-resolution QPE for a wide spectrum of applications. In this work, we formulate and comparatively evaluate four relatively simple procedures for such fusion based on Fisher estimation and its conditional bias-penalized variant: Direct Estimation (DE), Bias Correction (BC), Reduced-Dimension Bias Correction (RBC) and Simple Estimation (SE). They are applied to fuse the Multisensor Precipitation Estimator (MPE) and radar-only Next Generation QPE (Q2) products at the 15-min 1-km resolution (Experiment 1), and the MPE and Collaborative Adaptive Sensing of the Atmosphere (CASA) QPE products at the 15-min 500-m resolution (Experiment 2). The resulting fused estimates are evaluated using the 15-min rain gauge observations from the City of Grand Prairie in the Dallas-Fort Worth Metroplex (DFW) in north Texas. The main criterion used for evaluation is that the fused QPE improves over the ingredient QPEs at their native spatial resolutions, and that, at the higher resolution, the fused QPE improves not only over the ingredient higher-resolution QPE but also over the ingredient lower-resolution QPE trivially disaggregated using the ingredient high-resolution QPE. All four procedures assume that the ingredient QPEs are unbiased, which is not likely to hold true in reality even if real-time bias correction is in operation. To test robustness under more realistic conditions, the fusion procedures were evaluated with and

  11. 基于数字信号处理器的雷达教学系统设计%Design of the DSP Based Radar Training System

    Institute of Scientific and Technical Information of China (English)

    谷溪; 龚少军

    2012-01-01

    Radar is one of the important navigational aids on board. Students majoring in navigation techniques are required by STCW Convention to have special training in radar operation. In view of the situation that maritime colleges usually do not have sufficient real radars for hands-on training, a DSP based radar training system is developed, which transmits radar images to computers for radar training. The system meets the requirements of the radar training course and sets a good example to colleges.%雷达是船舶重要的导航设备之一,STCW规定航海技术专业学生在校期间必须进行雷达操作的专门训练.针对航海院校真实雷达数量少训练分组率不高的现状,设计出一款基于DSP技术的雷达教学系统,实现了雷达图像的计算机传输,满足了航海院校雷达教学的需求.该系统对航海院校雷达教学具有指导意义.

  12. Ground penetrating radar antenna measurements based on plane-wave expansions

    DEFF Research Database (Denmark)

    Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

    2005-01-01

    The plane-wave transmitting spectrum of the system consisting of the ground penetrating radar (GPR) antenna and the air-soil interface is measured using a loop buried in the soil. The plane-wave spectrum is used to determine various parameters characterizing the radiation of the GPR antenna into...... the soil. The procedure is tested on a spiral atenna....

  13. HF Radar Signal Processing Based on Tomographic Imaging and CS Technique

    Directory of Open Access Journals (Sweden)

    Qiang Yang

    2014-01-01

    Full Text Available This study presents the application of a spotlight-mode synthetic aperture radar (SAR imaging technique to the problem of high probablity target detection in high frequency (HF radar system, attempting to improve its spatial resolution. The effects of finite aperture on resolution, sampling constraints and reconstruction over a complete angular range of 360 degrees are discussed. A Convolution Back Projection (CBP algorithm has been applied to image reconstruction. In order to solve the range limitation of aspect angle with one radar-carrying platform, we collect data over a larger azimuthal range by making multi-aspect observations. Each straight line is a sub aperture over which we can perform the CBP algorithm. When we demand higher resolution for stationary target, it will cause blur with longer data acquisition time. Thus the application of the traditional imaging algorithm is limited. Compressed Sensing (CS has recently attracted much interest as it can reduce the number of samples without compromising the imaging quality. Within this motivation, we discuss the applicability of CS and present the application constraint for HF radar system.

  14. Verification of high resolution precipitation forecast by radar-based data

    Czech Academy of Sciences Publication Activity Database

    Řezáčová, Daniela; Szintai, B.; Jakubiak, B.; Yano, J.- I.; Turner, S.

    Vol. 2. London: Imperial College Press, 2016 - (Plant, R.), s. 173-214. (Series on the science of climate change. 1). ISBN 978-1-78326-694-4 R&D Projects: GA MŠk LD11044 Institutional support: RVO:68378289 Keywords : quantitative precipitation forecast QPF * forecast verification * spatial verification technique * precipitation measurement * meteorological radar Subject RIV: DG - Athmosphere Sciences, Meteorology

  15. MIDAS-W: a workstation-based incoherent scatter radar data acquisition system

    Directory of Open Access Journals (Sweden)

    J. M. Holt

    Full Text Available The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate hardware and low-level software implementation details from higher levels of the system. Inherent in this is the idea that implementation details can easily be changed in response to technological advances. MIDAS is an evolutionary system, and the MIDAS hardware has, in fact, evolved while the basic software model has remained unchanged. From the earliest days of MIDAS, it was realized that some functions implemented in specialized hardware might eventually be implemented by software in a general-purpose computer. MIDAS-W is the realization of this concept. The core component of MIDAS-W is a Sun Microsystems UltraSparc 10 workstation equipped with an Ultrarad 1280 PCI bus analog to digital (A/D converter board. In the current implementation, a 2.25 MHz intermediate frequency (IF is bandpass sampled at 1 µs intervals and these samples are multicast over a high-speed Ethernet which serves as a raw data bus. A second workstation receives the samples, converts them to filtered, decimated, complex baseband samples and computes the lag-profile matrix of the decimated samples. Overall performance is approximately ten times better than the previous MIDAS system, which utilizes a custom digital filtering module and array processor based correlator. A major advantage of MIDAS-W is its flexibility. A portable, single-workstation data acquisition system can be implemented by moving the software receiver and correlator programs to the workstation with the A/D converter. When the data samples are multicast, additional data processing systems, for example for raw data recording, can be implemented simply by adding another workstation with suitable software to the high-speed network. Testing of new data processing software is also greatly

  16. MIDAS-W: a workstation-based incoherent scatter radar data acquisition system

    Science.gov (United States)

    Holt, J. M.; Erickson, P. J.; Gorczyca, A. M.; Grydeland, T.

    2000-09-01

    The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS) is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate hardware and low-level software implementation details from higher levels of the system. Inherent in this is the idea that implementation details can easily be changed in response to technological advances. MIDAS is an evolutionary system, and the MIDAS hardware has, in fact, evolved while the basic software model has remained unchanged. From the earliest days of MIDAS, it was realized that some functions implemented in specialized hardware might eventually be implemented by software in a general-purpose computer. MIDAS-W is the realization of this concept. The core component of MIDAS-W is a Sun Microsystems UltraSparc 10 workstation equipped with an Ultrarad 1280 PCI bus analog to digital (A/D) converter board. In the current implementation, a 2.25 MHz intermediate frequency (IF) is bandpass sampled at 1 µs intervals and these samples are multicast over a high-speed Ethernet which serves as a raw data bus. A second workstation receives the samples, converts them to filtered, decimated, complex baseband samples and computes the lag-profile matrix of the decimated samples. Overall performance is approximately ten times better than the previous MIDAS system, which utilizes a custom digital filtering module and array processor based correlator. A major advantage of MIDAS-W is its flexibility. A portable, single-workstation data acquisition system can be implemented by moving the software receiver and correlator programs to the workstation with the A/D converter. When the data samples are multicast, additional data processing systems, for example for raw data recording, can be implemented simply by adding another workstation with suitable software to the high-speed network. Testing of new data processing software is also greatly simplified, because a

  17. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar

    Directory of Open Access Journals (Sweden)

    Eugin Hyun

    2016-01-01

    Full Text Available For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method.

  18. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  19. 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.

  20. Radar signal analysis of ballistic missile with micro-motion based on time-frequency distribution

    Science.gov (United States)

    Wang, Jianming; Liu, Lihua; Yu, Hua

    2015-12-01

    The micro-motion of ballistic missile targets induces micro-Doppler modulation on the radar return signal, which is a unique feature for the warhead discrimination during flight. In order to extract the micro-Doppler feature of ballistic missile targets, time-frequency analysis is employed to process the micro-Doppler modulated time-varying radar signal. The images of time-frequency distribution (TFD) reveal the micro-Doppler modulation characteristic very well. However, there are many existing time-frequency analysis methods to generate the time-frequency distribution images, including the short-time Fourier transform (STFT), Wigner distribution (WD) and Cohen class distribution, etc. Under the background of ballistic missile defence, the paper aims at working out an effective time-frequency analysis method for ballistic missile warhead discrimination from the decoys.

  1. Angel estimation via frequency diversity of the SIAR radar based on Bayesian theory

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The orthogonal signals of multi-carrier-frequency emission and multiple antennas receipt module are used in SIAR radar.The corresponding received echo is equivalent to non-uniform spatial sampling after the frequency diversity process.As using the traditional Fourier transform will result in the target spectral with large sidelobe,the method presented in this paper firstly makes the preordering treatment for the position of the received antenna.Then,the Bayesian maximum posteriori estimation with l2-norm weighted constraint is utilized to achieve the equivalent uniform array echo.The simulations present the spectrum estimation in angle precision estimation of multiple targets under different SNRs,different virtual antenna numbers and different elevations.The estimation results confirm the advantage of SIAR radar both in array expansion and angle estimation.

  2. The effect of radar-based QPE on the verification of QPF for convective rainfalls

    Czech Academy of Sciences Publication Activity Database

    Zacharov, Petr, jr.; Řezáčová, Daniela

    Helsinki : Finnish meteorological institute, 2008, ---. ISBN 978-951-697-676-4. [ERAD 2008 - European Conference on Radar in Meteorology and Hydrology /5./. Helsinki (FI), 30.06.2008-4.07.2008] R&D Projects: GA MŠk OC 112; GA AV ČR(CZ) IAA300420804; GA ČR GA205/07/0905 Institutional research plan: CEZ:AV0Z30420517 Keywords : precipitation forecast * nowcasting * local convective storm * flash flood Subject RIV: DG - Athmosphere Sciences, Meteorology

  3. Radar-based QPE for the modeler oriented QPF verification by traditional and spatial techniques

    Czech Academy of Sciences Publication Activity Database

    Řezáčová, Daniela; Zacharov, Petr, jr.; Sokol, Zbyněk

    Toulouse : Météo France, 2012, s. 1-3. [ERAD 2012 - European Conference on Radar in Meteorology and Hydrology /7./. Toulouse (FR), 24.06.2012-29.06.2012] R&D Projects: GA MŠk LD11044 Institutional support: RVO:68378289 Keywords : quantitative precipitation forecast * quantitative precipitation estimate * NWP model COSMO Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.meteo.fr/cic/meetings/2012/ERAD/extended_abs/NWP_323_ext_abs.pdf

  4. Stochastic-dynamical rainfall simulation based on weather radar volume scan data

    OpenAIRE

    Andrieu, H.; FRENCH, MN; KRAJEWESKI, WF; GEORGAKAKOS, KP

    2003-01-01

    The authors present a new conceptual approach to rainfall simulation for hydrologic model studies. The simulation method addresses needs of operational hydrometeorological systems and the model formulation uses the characteristics of operationally available space-time observations of rainfall. The primary state of the simulation model is the vertically-integrated rainwater content derived from radar reflectivity. The simulation model components represent the formation of surface rainfall f...

  5. Classification of Convective and Stratiform Cells in Meteorological Radar Images Using SVM Based on a Textural Analysis

    Institute of Scientific and Technical Information of China (English)

    Abdenasser Djafri; Boualem Haddad

    2014-01-01

    This contribution deals with the discrimination between stratiform and convective cells in meteorological radar images. This study is based on a textural analysis of the latter and their classification using a support vector machine (SVM). First, we apply different textural parameters such as energy, entropy, inertia, and local homogeneity. Through this experience, we identify the different textural features of both the stratiform and convective cells. Then, we use an SVM to find the best discriminating parameter between the two types of clouds. The main goal of this work is to better apply the Palmer and Marshall Z-R relations specific to each type of precipitation.

  6. Microwave Doppler radar in unobtrusive health monitoring

    International Nuclear Information System (INIS)

    This article frames the use of microwave Doppler radar in the context of ubiquitous, non-obstructive health monitoring. The use of a 24GHz CW (continuous wave) Doppler radar based on a commercial off-the-shelf transceiver for remote sensing of heart rate and respiration rate based on the acquisition and processing of the signals delivered by the radar is briefly presented

  7. Digital Receiver-based Electronic Intelligence System Configuration for the Detection and Identification of Intrapulse Modulated Radar Signals

    Directory of Open Access Journals (Sweden)

    A. K. Singh

    2014-03-01

    Full Text Available An optimum electronic intelligence system configuration incorporating the state of the art technologies and achieving the highest parameter accuracies while processing the complex intrapulse modulated radar signals is presented in this paper. The system is based on the quad digital receiver, a state of the art single board solution for the detection and analysis of modern radar signals. The system consists of base line interferometry  configuration for high accuracy direction finding measurement with sector selection based on amplitude direction finding technique. Advanced signal processing algorithms with time frequency analysis are implemented in real time in field programmable gate array to extract all the basic as well as advanced parameters of frequency and phase modulations such as chirp, barker, and poly-phase (Frank, P1-P4 codes in addition to the pulse and continuous wave signals. The intercepted intrapulse modulated signal parameters have been extracted with very high accuracy and sensitivity.Defence Science Journal, 2014, 64(2, pp. 152-158. DOI: http://dx.doi.org/10.14429/dsj.64.5091

  8. Radar Target Classification Using Neural Network and Median Filter

    OpenAIRE

    J. Kurty; Z. Matousek

    2001-01-01

    The paper deals with Radar Target Classification based on the use of a neural network. A radar signal was acquired from the output of a J frequency band noncoherent radar. We applied the three layer feed forward neural network using the backpropagation learning algorithm. We defined classes of radar targets and designated each of them by its number. Our classification process resulted in the number of a radar target class, which the radar target belongs to.

  9. Analysis of warm season thunderstorms using an object-oriented tracking method based on radar and total lightning data

    Science.gov (United States)

    Rigo, T.; Pineda, N.; Bech, J.

    2010-09-01

    Monitoring thunderstorms activity is an essential part of operational weather surveillance given their potential hazards, including lightning, hail, heavy rainfall, strong winds or even tornadoes. This study has two main objectives: firstly, the description of a methodology, based on radar and total lightning data to characterise thunderstorms in real-time; secondly, the application of this methodology to 66 thunderstorms that affected Catalonia (NE Spain) in the summer of 2006. An object-oriented tracking procedure is employed, where different observation data types generate four different types of objects (radar 1-km CAPPI reflectivity composites, radar reflectivity volumetric data, cloud-to-ground lightning data and intra-cloud lightning data). In the framework proposed, these objects are the building blocks of a higher level object, the thunderstorm. The methodology is demonstrated with a dataset of thunderstorms whose main characteristics, along the complete life cycle of the convective structures (development, maturity and dissipation), are described statistically. The development and dissipation stages present similar durations in most cases examined. On the contrary, the duration of the maturity phase is much more variable and related to the thunderstorm intensity, defined here in terms of lightning flash rate. Most of the activity of IC and CG flashes is registered in the maturity stage. In the development stage little CG flashes are observed (2% to 5%), while for the dissipation phase is possible to observe a few more CG flashes (10% to 15%). Additionally, a selection of thunderstorms is used to examine general life cycle patterns, obtained from the analysis of normalized (with respect to thunderstorm total duration and maximum value of variables considered) thunderstorm parameters. Among other findings, the study indicates that the normalized duration of the three stages of thunderstorm life cycle is similar in most thunderstorms, with the longest

  10. Analysis of warm season thunderstorms using an object-oriented tracking method based on radar and total lightning data

    Directory of Open Access Journals (Sweden)

    T. Rigo

    2010-09-01

    Full Text Available Monitoring thunderstorms activity is an essential part of operational weather surveillance given their potential hazards, including lightning, hail, heavy rainfall, strong winds or even tornadoes. This study has two main objectives: firstly, the description of a methodology, based on radar and total lightning data to characterise thunderstorms in real-time; secondly, the application of this methodology to 66 thunderstorms that affected Catalonia (NE Spain in the summer of 2006. An object-oriented tracking procedure is employed, where different observation data types generate four different types of objects (radar 1-km CAPPI reflectivity composites, radar reflectivity volumetric data, cloud-to-ground lightning data and intra-cloud lightning data. In the framework proposed, these objects are the building blocks of a higher level object, the thunderstorm.

    The methodology is demonstrated with a dataset of thunderstorms whose main characteristics, along the complete life cycle of the convective structures (development, maturity and dissipation, are described statistically. The development and dissipation stages present similar durations in most cases examined. On the contrary, the duration of the maturity phase is much more variable and related to the thunderstorm intensity, defined here in terms of lightning flash rate. Most of the activity of IC and CG flashes is registered in the maturity stage. In the development stage little CG flashes are observed (2% to 5%, while for the dissipation phase is possible to observe a few more CG flashes (10% to 15%. Additionally, a selection of thunderstorms is used to examine general life cycle patterns, obtained from the analysis of normalized (with respect to thunderstorm total duration and maximum value of variables considered thunderstorm parameters. Among other findings, the study indicates that the normalized duration of the three stages of thunderstorm life cycle is similar in most thunderstorms

  11. Equatorial scintillation calculations based on coherent scatter radar and C/NOFS data

    Science.gov (United States)

    Costa, Emanoel; de Paula, Eurico R.; Rezende, L. F. C.; Groves, Keith M.; Roddy, Patrick A.; Dao, Eugene V.; Kelley, Michael C.

    2011-04-01

    During its transit through a region of equatorial ionospheric irregularities, sensors on board the Communication/Navigation Outage Forecasting System (C/NOFS) satellite provide a one-dimensional description of the medium, which can be extended to two dimensions if the structures are assumed to be elongated in the direction of the magnetic field lines. The C/NOFS scintillation calculation approach assumes that the medium is equivalent to a diffracting screen with random phase fluctuations that are proportional to the irregularities in the total electron content, specified through the product of the directly measured electron density by an estimated extent of the irregularity layer along the raypaths. Within the international collaborative effort anticipated by the C/NOFS Science Definition Team, the present work takes the vertical structure of the irregularities into more detailed consideration, which could lead to improved predictions of scintillation. Initially, it describes a flexible model for the power spectral density of the equatorial ionospheric irregularities, estimates its shape parameters from C/NOFS in situ data and uses the signal-to-noise ratio S/N measurements by the São Luís coherent scatter radar to estimate the mean square electron density fluctuation within the corresponding sampled volume. Next, it presents an algorithm for the wave propagation through a three-dimensional irregularity layer which considers the variations of along the propagation paths according to observations by the radar. Data corresponding to several range-time-intensity maps from the radar is used to predict time variations of the scintillation index S4 at the L1 Global Positioning System (GPS) frequency (1575.42 MHz). The results from the scintillation calculations are compared with corresponding measurements by the colocated São Luís GPS scintillation monitor for an assessment of the prediction capability of the present formulation.

  12. Weather Radar Stations

    Data.gov (United States)

    Department of Homeland Security — These data represent Next-Generation Radar (NEXRAD) and Terminal Doppler Weather Radar (TDWR) weather radar stations within the US. The NEXRAD radar stations are...

  13. The use of radar-based QPE in the HR QPF verification

    Czech Academy of Sciences Publication Activity Database

    Zacharov, Petr, jr.; Řezáčová, Daniela; Brožková, K.

    Oberpfaffenhofen-Wessling : Institut für Physik der Atmosphäre, 2014. [ERAD 2014 - 8th European Conference on Radar in Meteorology and Hydrology. 01.09.2014-05.09.2014, Garmisch-Partenkirchen] R&D Projects: GA MŠk LD11044; GA ČR(CZ) GPP209/12/P701 Institutional support: RVO:68378289 Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.pa.op.dlr.de/erad2014/programme/ExtendedAbstracts/084_Zacharov.pdf

  14. Extended Target Recognition in Cognitive Radar Networks

    Directory of Open Access Journals (Sweden)

    Xiqin Wang

    2010-11-01

    Full Text Available We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR based sequential hypothesis testing (SHT framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS. Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches.

  15. High resolution through-the-wall radar image based on beamspace eigenstructure subspace methods

    Science.gov (United States)

    Yoon, Yeo-Sun; Amin, Moeness G.

    2008-04-01

    Through-the-wall imaging (TWI) is a challenging problem, even if the wall parameters and characteristics are known to the system operator. Proper target classification and correct imaging interpretation require the application of high resolution techniques using limited array size. In inverse synthetic aperture radar (ISAR), signal subspace methods such as Multiple Signal Classification (MUSIC) are used to obtain high resolution imaging. In this paper, we adopt signal subspace methods and apply them to the 2-D spectrum obtained from the delay-andsum beamforming image. This is in contrast to ISAR, where raw data, in frequency and angle, is directly used to form the estimate of the covariance matrix and array response vector. Using beams rather than raw data has two main advantages, namely, it improves the signal-to-noise ratio (SNR) and can correctly image typical indoor extended targets, such as tables and cabinets, as well as point targets. The paper presents both simulated and experimental results using synthesized and real data. It compares the performance of beam-space MUSIC and Capon beamformer. The experimental data is collected at the test facility in the Radar Imaging Laboratory, Villanova University.

  16. Bistatic radar

    CERN Document Server

    Willis, Nick

    2004-01-01

    Annotation his book is a major extension of a chapter on bistatic radar written by the author for the Radar Handbook, 2nd edition, edited by Merrill Skolnik. It provides a history of bistatic systems that points out to potential designers the applications that have worked and the dead-ends not worth pursuing. The text reviews the basic concepts and definitions, and explains the mathematical development of relationships, such as geometry, Ovals of Cassini, dynamic range, isorange and isodoppler contours, target doppler, and clutter doppler spread.Key Features * All development and analysis are

  17. Research of Combat Behavior Model Of Agent-Based Radar Networks%基于Agent的雷达网对抗行为模型*

    Institute of Scientific and Technical Information of China (English)

    张枣; 司光亚; 赵晔

    2013-01-01

      雷达网在对抗中展现出的自适应性是体系对抗的重要特征,是提高雷达网情报获取质量和抗毁伤能力的关键。在分析雷达网对抗过程的基础上,提出了基于Agent的雷达网对抗行为仿真模型实现方法。通过想定背景下的仿真实验,验证了模型的有效性,实现了体系对抗条件下雷达网自适应对抗行为的仿真建模。%The adaptability that radar networks shows in combat is the important feature of system-of-systems combat and the key to improve the quality of the acquired data and the ability of invulnerability for radar networks. Based on the analysis of Radar networks combat process,a method based on Agent is proposed to establish combat behavior model of radar networks. The model’s usability is validated using the simulation experimentation method under scenario background,and modeling of adaptive combat behavior of radar networks is realized in system-of-systems combat.

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

    Science.gov (United States)

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

    2016-06-01

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

  19. Multi-Feature Based Multiple Landmine Detection Using Ground Penetration Radar

    Directory of Open Access Journals (Sweden)

    S. Park

    2014-06-01

    Full Text Available This paper presents a novel method for detection of multiple landmines using a ground penetrating radar (GPR. Conventional algorithms mainly focus on detection of a single landmine, which cannot linearly extend to the multiple landmine case. The proposed algorithm is composed of four steps; estimation of the number of multiple objects buried in the ground, isolation of each object, feature extraction and detection of landmines. The number of objects in the GPR signal is estimated by using the energy projection method. Then signals for the objects are extracted by using the symmetry filtering method. Each signal is then processed for features, which are given as input to the support vector machine (SVM for landmine detection. Three landmines buried in various ground conditions are considered for the test of the proposed method. They demonstrate that the proposed method can successfully detect multiple landmines.

  20. Microcontroller-based binary integrator for millimeter-wave radar experiments

    Science.gov (United States)

    Eskelinen, Pekka; Ruoskanen, Jukka; Peltonen, Jouni

    2010-05-01

    An easily on-site reconfigurable multiple binary integrator for millimeter radar experiments has been constructed of static random access memories, an eight bit microcontroller, and high speed video operational amplifiers. The design uses a raw comparator path and two adjustable m-out-of-n chains in a wired-OR configuration. Standard high speed memories allow the use of pulse widths below 100 ns. For eight pulse repetition intervals it gives a maximum improvement of 6.6 dB for stationary low-level target echoes. The doubled configuration enhances the capability against fluctuating targets. Because of the raw comparator path, also single return pulses of relatively high amplitude are processed.

  1. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  3. Enhanced Weather Radar (EWxR) System

    Science.gov (United States)

    Kronfeld, Kevin M. (Technical Monitor)

    2003-01-01

    An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

  4. A Digital Elevation Model of the Greenland Ice Sheet based on Envisat and CryoSat-2 Radar Altimetry

    Science.gov (United States)

    Levinsen, J. F.; Smith, B. E.; Sandberg Sørensen, L.; Khvorostovsky, K.; Forsberg, R.

    2014-12-01

    With the launch of the first radar altimeter by ESA in 1992, more than two decades of radar altimetry data are now available. Therefore, one goal of ESA's Ice Sheet Climate Change Initiative is the estimation of surface elevation changes of the Greenland Ice Sheet (GrIS) based on ERS-1, -2, Envisat, CryoSat-2, and, in the longer term, Sentinel-3 data. This will create a data record from 1992 until present date. In addition to elevation-change records, such data can be processed to produce digital elevation models, or DEMs, of the ice sheets. The DEMs can be used to correct radar altimetry data for slope-induced errors resulting from the large footprint (e.g. 2-10 km for Envisat vs. 60 m for ICESat laser altimetry) or to correct for the underlying surface topography when applying the repeat-track method. DEMs also provide key information in e.g. SAR remote sensing of ice velocities to remove the interferograms' topographic signal or in regional climate modeling. This work focuses on the development of a GrIS DEM from Envisat and CryoSat-2 altimetry, corrected with temporally and spatially coincident NASA ICESat, ATM, and LVIS laser data. The spatial resolution is 2 x 2 km and the reference year 2010. It is based on 2009 and 2010 data, the 2009 data adjusted to 2010 by accounting for the intermediate elevation changes. This increases the spatial data coverage and reduces data errors. The GIMP DEM has been corrected for negative elevations and errors in the north, and used to constrain the final DEM. The recently acquired observations and increased data coverage give a strong advantage to this DEM relative to previous models, based on lower-resolution, more temporally scattered data (e.g. a decade of observations or only ICESat data, limited to three annual 35-day acquisition periods). Furthermore, as surface changes occur continuously, an up-to-date DEM is necessary to correctly constrain the observations, thereby ensuring an accurate change detection or modeling

  5. Dynamic gauge adjustment of high-resolution X-band radar data for convective rain storms: Model-based evaluation against measured combined sewer overflow

    Science.gov (United States)

    Borup, Morten; Grum, Morten; Linde, Jens Jørgen; Mikkelsen, Peter Steen

    2016-08-01

    Numerous studies have shown that radar rainfall estimates need to be adjusted against rain gauge measurements in order to be useful for hydrological modelling. In the current study we investigate if adjustment can improve radar rainfall estimates to the point where they can be used for modelling overflows from urban drainage systems, and we furthermore investigate the importance of the aggregation period of the adjustment scheme. This is done by continuously adjusting X-band radar data based on the previous 5-30 min of rain data recorded by multiple rain gauges and propagating the rainfall estimates through a hydraulic urban drainage model. The model is built entirely from physical data, without any calibration, to avoid bias towards any specific type of rainfall estimate. The performance is assessed by comparing measured and modelled water levels at a weir downstream of a highly impermeable, well defined, 64 ha urban catchment, for nine overflow generating rain events. The dynamically adjusted radar data perform best when the aggregation period is as small as 10-20 min, in which case it performs much better than static adjusted radar data and data from rain gauges situated 2-3 km away.

  6. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array.

    Science.gov (United States)

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile's rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm. PMID:26978372

  7. Software Radar Technology

    OpenAIRE

    Tang Jun; Wu Hong; Wei Kun-peng

    2015-01-01

    In this paper, the definition and the key features of Software Radar, which is a new concept, are proposed and discussed. We consider the development of modern radar system technology to be divided into three stages: Digital Radar, Software radar and Intelligent Radar, and the second stage is just commencing now. A Software Radar system should be a combination of various modern digital modular components conformed to certain software and hardware standards. Moreover, a software radar system w...

  8. Performance evaluation of lunar penetrating radar onboard the rover of CE-3 probe based on results from ground experiments

    Science.gov (United States)

    Zhang, Hong-Bo; Zheng, Lei; Su, Yan; Fang, Guang-You; Zhou, Bin; Feng, Jian-Qing; Xing, Shu-Guo; Dai, Shun; Li, Jun-Duo; Ji, Yi-Cai; Gao, Yun-Ze; Xiao, Yuan; Li, Chun-Lai

    2014-12-01

    Lunar Penetrating Radar (LPR) onboard the rover that is part of the Chang'e-3 (CE-3) mission was firstly utilized to obtain in situ measurements about geological structure on the lunar surface and the thickness of the lunar regolith, which are key elements for studying the evolutional history of lunar crust. Because penetration depth and resolution of LPR are related to the scientific objectives of this mission, a series of ground-based experiments using LPR was carried out, and results of the experimental data were obtained in a glacial area located in the northwest region of China. The results show that the penetration depth of the first channel antenna used for LPR is over 79 m with a resolution of 2.8 m, and that for the second channel antenna is over 50.8 m with a resolution of 17.1 cm.

  9. Performance evaluation of lunar penetrating radar onboard the rover of CE-3 probe based on results from ground experiments

    International Nuclear Information System (INIS)

    Lunar Penetrating Radar (LPR) onboard the rover that is part of the Chang'e-3 (CE-3) mission was firstly utilized to obtain in situ measurements about geological structure on the lunar surface and the thickness of the lunar regolith, which are key elements for studying the evolutional history of lunar crust. Because penetration depth and resolution of LPR are related to the scientific objectives of this mission, a series of ground-based experiments using LPR was carried out, and results of the experimental data were obtained in a glacial area located in the northwest region of China. The results show that the penetration depth of the first channel antenna used for LPR is over 79 m with a resolution of 2.8 m, and that for the second channel antenna is over 50.8 m with a resolution of 17.1 cm

  10. Web-based Tools for Educators: Outreach Activities of the Polar Radar for Ice Sheet Measurements (PRISM) Project

    Science.gov (United States)

    Braaten, D. A.; Holvoet, J. F.; Gogineni, S.

    2003-12-01

    The Radar Systems and Remote Sensing Laboratory at the University of Kansas (KU) has implemented extensive outreach activities focusing on Polar Regions as part of the Polar Radar for Ice Sheet Measurements (PRISM) project. The PRISM project is developing advanced intelligent remote sensing technology that involves radar systems, an autonomous rover, and communications systems to measure detailed ice sheet characteristics, and to determine bed conditions (frozen or wet) below active ice sheets in both Greenland and Antarctica. These measurements will provide a better understanding of the response of polar ice sheets to global climate change and the resulting impact the ice sheets will have on sea level rise. Many of the research and technological development aspects of the PRISM project, such as robotics, radar systems, climate change and exploration of harsh environments, can kindle an excitement and interest in students about science and technology. These topics form the core of our K-12 education and training outreach initiatives, which are designed to capture the imagination of young students, and prompt them to consider an educational path that will lead them to scientific or engineering careers. The K-12 PRISM outreach initiatives are being developed and implemented in a collaboration with the Advanced Learning Technology Program (ALTec) of the High Plains Regional Technology in Education Consortium (HPR*TEC). ALTec is associated with the KU School of Education, and is a well-established educational research center that develops and hosts web tools to enable teachers nationwide to network, collaborate, and share resources with other teachers. An example of an innovative and successful web interface developed by ALTec is called TrackStar. Teachers can use TrackStar over the Web to develop interactive, resource-based lessons (called tracks) on-line for their students. Once developed, tracks are added to the TrackStar database and can be accessed and modified

  11. Ground-Based Real-Aperture Radar Interferometry: Techniques and Potential for Measurement of mm-Scale Motion

    Science.gov (United States)

    Werner, C. L.; Wiesmann, A.; Kos, A.; Caduff, R.; Strozzi, T.; Wegmüller, U.

    2011-12-01

    Ground-based radar interferometry is an emerging geodetic imaging technology that has been applied to measurement of landslides, rockfalls, glaciers, and mines. Geo-technical observations have been performed of infrastructure including bridges and dams. Compared with spaceborne radar systems, ground-based observations have advantages with respect to the selection of the imaging geometry to optimize visibility and sensitivity to deformation, shorter repeat intervals for monitoring rapidly moving features, and higher sensitivity to motion along the line-of-sight (LOS) due to the shorter wavelength and potential for averaging of multiple observations. The GPRI instrument developed by Gamma Remote Sensing is an FM-CW radar operating at 17.2 GHz (λ: 17.4 mm) with a range resolution of 90 cm along the line of sight and an operational range from 20 meters to 16 km. The GPRI is a real-aperture instrument using a 2.06 m long waveguide antenna to generate a fan-beam that is 0.4 x 35 degrees. During data acquisition, the radar performs a rotary scan of the scene at a programmable rate between 0.5 and 10 degrees/sec. Azimuth resolution is linearly proportional to slant range with a value of 7m at 1 km distance. Differential motion of 8.71 mm results in 2PI radians of measurable phase between observations. The GPRI incorporates two receivers enabling simultaneous interferometric observation with a vertical baseline variable between 25 and 60 cm. The single transmitting antenna and 2 receiving antennas are mounted parallel to one another on a rigid tower attached to a rotary positioner. An internal GPS receiver provides a time and frequency reference permitting simultaneous operation of multiple GPRI systems. The GPRI operates in four possible data acquisition modes permitting a wide range of applications. The first mode is the simultaneous interferometric mode using the upper and lower receiving antennas. The interferometric phase can be used to derive an elevation model

  12. Capabilities of Earth-based radar facilities for near-Earth asteroid observations

    CERN Document Server

    Naidu, Shantanu P; Margot, Jean-Luc; Busch, Michael W; Taylor, Patrick A

    2016-01-01

    We evaluated the planetary radar capabilities at Arecibo, the Goldstone 70 m DSS-14 and 34-m DSS-13 antennas, the 70-m DSS-43 antenna at Canberra, the Green Bank Telescope, and the Parkes Radio Telescope in terms of their relative sensitivities and the number of known near-Earth asteroids (NEAs) detectable per year in monostatic and bistatic configurations. In the 2015 calendar year, monostatic observations with Arecibo and DSS-14 were capable of detecting 253 and 131 NEAs respectively. Combined, the two observatories were capable of detecting 276 unique NEAs. Of these, Arecibo detected 95 and Goldstone detected 39, or 38% and 30% the numbers that were possible. This indicates that a substantial number of potential targets are not being observed. The bistatic configuration with DSS-14 transmitting and the Green Bank Telescope receiving was capable of detecting about 195 NEAs, or ~50% more than with monostatic observations at DSS-14. Most of the detectable asteroids were targets-of-opportunity that were discov...

  13. Coordinated data on auroral electrodynamics from ground based radar diagnostics and Aureol-3 satellite

    International Nuclear Information System (INIS)

    Coordinated ground-satellite measurements of VHF radar arcs, magnetic variations and all-sky auroral imagery were performed from Kola-peninsula and from Finland together with direct particle and field measurements from AUREOL-3 satellite. The detailed analysis of two satellite passes in the evening (midnight) MLT sector in the conditions of predominantly northward (westward) ionospheric electric field show that inverted V-associated electrodynamical pattern was the same in both events. Model calculations summarizing all the above ionosphere-satellite results within the limits of unified electrodynamical scheme show that a) meridional ionospheric (Hall+Pedersen) closing current direction is a decisive factor controlling the direction of currents in the meridional Birkeland current loop of the inverted V. A summarizing interpretative scheme is proposed of the hierarchy of meridional Birkeland current loops, larger one encircling single, or multiple, smaller ones: zone 2/zone 1 large-scale current loop, inverted V current loops, and auroral arc-associated current loops, all with the same direction of the ionospheric closing current, northward in the evening and southward in the morning

  14. Lake levels based on CryoSat-2 SAR radar altimetry

    Science.gov (United States)

    Nielsen, K.; Villadsen, H.; Stenseng, L.; Andersen, O. B.; Knudsen, P.

    2015-12-01

    CryoSat-2 is the satellite that carries a synthetic aperture radar (SAR) altimeter on-board. The SAR technology provides an along-track resolution of approximately 300 m. The higher resolution makes it possible to accurately monitor much smaller water bodies than previously. In this study, which is part of the FP7 project Land and Ocean take up from Sentinel-3 (LOTUS), we investigate the potential of SAR altimetry. To derive lake levels we use novel empirical threshold retrackers and the physical SAMOSA retracker. We consider lakes at various sizes and evaluate the CryoSat-2 derived lake levels in terms of along-track precision and agreement with in-situ data. We find that the precision of the along-track mean water level is a few cm, even for lakes with a surface area of just 9 km^2. The high precision makes it possible to detect water level variations below the decimeter level. To derive lake level time series we apply a state-space model with a robust handling of erroneous data. Instead of attempting to identify and remove the polluted observations we use a mixture distribution to describe the observation noise, which prevents the polluted observations from biasing our final reconstructed time series. These results demonstrate the promising possibilities of the upcoming Sentinel-3 mission, which potentially will be able to provide accurate time series for small lakes.

  15. Research on high precision timing system based on FPGA non scanning imaging laser radar

    Science.gov (United States)

    Fu, Yanbo; Han, Shaokun; Wang, Liang; Ma, Yayun

    2015-08-01

    The article introduced the system structure and imaging principle of no three-dimensional imaging laser radar. This paper used the XC7K325T XILINX chip of KINTEX 7 series and used temporal interpolation method to measure distance. Rough side used PLL multiplier 400MHZ, which reached 2.5ns time accuracy. This method used a thin chip delay chains carry resources to reach 50ps accuracy and greatly improved the accuracy of the timing of imaging. Application technique used a delay line in APD array imaging system, such that each channel distance accuracy greatly improved. Echo signal by photoelectric conversion is completed by APD array detector, and designed by the impedance amplifier and other analog signal processing circuit. FPGA signal processing circuit is to complete the back-end processing, which is the timing function. FPGA array timer clock is to achieve coarse portion through timing, and delay line technique for measuring the length of time a non-integer multiple of the period of the laser pulse emission and the moment of reception, each stage of the delay units delay accuracy of sub ns magnitude, so as to achieve precision measuring part timers. With the above device was close imaging experiments, obtaining the 5 × 5 pixel imaging test results, presented to further improve system accuracy improved method.

  16. 大气波导对舰载及岸基雷达的影响%The effects of atmospheric duct on shipborne and shore-based radars

    Institute of Scientific and Technical Information of China (English)

    王明明; 陆敏

    2012-01-01

    大气波导是海洋大气环境的一种常见现象,这种现象使电磁波的传播超出了地球曲率的限制,从而使岸基雷达及舰载雷达受到大量的杂波干扰。针对舰载雷达及架设高度较低的岸基雷达,本文分析了大气波导现象对其探测水面及空中目标的影响,并给出了利用大气波导现象实现雷达超视距探测的基本方法。%The atmospheric duct is a common phenomenon in the atmospheric environment of the o- cean, making the electromagnetic wave travel beyond the limit of the earth curvature and causing the shipborne and shore-based radars to be subject to a lot of clutter interference. Based on the shipborne radars and the shore-based radars with lower height, the effects of the atmospheric duct on detecting the surface and air targets are analyzed, and the basic method of realizing the OTH radar detection through the atmospheric duct is given.

  17. Limitations of Radar Coordinates

    OpenAIRE

    Bini, Donato; Lusanna, Luca; Mashhoon, Bahram

    2004-01-01

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  18. Bistatic and Multistatic Radar Systems

    OpenAIRE

    Bezousek, P.; V. Schejbal

    2008-01-01

    Radar systems, based on bistatic radar concept attracted a substantial attention in the recent years. Passive coherent location systems using \\"transmitters of opportunity\\" like radio or TV broadcasters, GSM base stations, satellite communication and GNSS signals proved their potential in detection and tracking moving targets over a significant area. In this paper the multistatic location system with non-cooperative transmitters is described and various aspects of signal processing and signa...

  19. Bistatic and Multistatic Radar Systems

    OpenAIRE

    V. Schejbal; Bezousek, P.

    2008-01-01

    Radar systems, based on bistatic radar concept attracted a substantial attention in the recent years. Passive coherent location systems using "transmitters of opportunity" like radio or TV broadcasters, GSM base stations, satellite communication and GNSS signals proved their potential in detection and tracking moving targets over a significant area. In this paper the multistatic location system with non-cooperative transmitters is described and various aspects of signal processing and signal ...

  20. Bistatic and Multistatic Radar Systems

    Directory of Open Access Journals (Sweden)

    V. Schejbal

    2008-09-01

    Full Text Available Radar systems, based on bistatic radar concept attracted a substantial attention in the recent years. Passive coherent location systems using "transmitters of opportunity" like radio or TV broadcasters, GSM base stations, satellite communication and GNSS signals proved their potential in detection and tracking moving targets over a significant area. In this paper the multistatic location system with non-cooperative transmitters is described and various aspects of signal processing and signal parameters are discussed.

  1. Crop monitoring & yield forecasting system based on Synthetic Aperture Radar (SAR) and process-based crop growth model: Development and validation in South and South East Asian Countries

    Science.gov (United States)

    Setiyono, T. D.

    2014-12-01

    Accurate and timely information on rice crop growth and yield helps governments and other stakeholders adapting their economic policies and enables relief organizations to better anticipate and coordinate relief efforts in the wake of a natural catastrophe. Such delivery of rice growth and yield information is made possible by regular earth observation using space-born Synthetic Aperture Radar (SAR) technology combined with crop modeling approach to estimate yield. Radar-based remote sensing is capable of observing rice vegetation growth irrespective of cloud coverage, an important feature given that in incidences of flooding the sky is often cloud-covered. The system allows rapid damage assessment over the area of interest. Rice yield monitoring is based on a crop growth simulation and SAR-derived key information, particularly start of season and leaf growth rate. Results from pilot study sites in South and South East Asian countries suggest that incorporation of SAR data into crop model improves yield estimation for actual yields. Remote-sensing data assimilation into crop model effectively capture responses of rice crops to environmental conditions over large spatial coverage, which otherwise is practically impossible to achieve. Such improvement of actual yield estimates offers practical application such as in a crop insurance program. Process-based crop simulation model is used in the system to ensure climate information is adequately captured and to enable mid-season yield forecast.

  2. Capacidade combinatoria de capim elefante com base em caracteres morfoagronomicos

    Directory of Open Access Journals (Sweden)

    Vanessa Quitete Ribeiro da Silva

    2014-01-01

    Full Text Available Devido ao grande potencial de produção de biomassa do capim elefante, objetivou-se neste trabalho avaliar genitores para geração de híbridos superiores. Para tanto, foram estimados os efeitos da capacidade geral de combinação (CGC dos genitores e da capacidade específica de combinação (CEC de híbridos de capim elefante por meio de análise dialélica adaptada a dialelos parciais. Foram avaliados 16 híbridos e oito genitores utilizando delineamento em blocos casualizados com três repetições. Verificou-se a presença de variabilidade genética entre os híbridos e genitores, com predominância do efeito gênico de dominância para a maioria das características. De forma geral, os melhores resultados na CGC são os genitores Taiwan A-144, Vruckwona Africana e Taiwan A-146. Os melhores cruzamentos com base na CEC são Taiwan A-144 x Taiwan A-146 e Pusa Napier nº2 x Mercker Santa Rita.

  3. Arctic Cloud Fraction and Microphysical Characteristics from 8-year Space-based Lidar and Radar Measurements

    Science.gov (United States)

    Kim, S. W.; Yeo, H.; Jeong, J. H.; Kim, M. H.; Son, S. W.; Kim, B. M.; Kim, S. J.

    2015-12-01

    Arctic clouds are a key factor in determining the energy budget both at the top of the atmosphere and at the suface by modulating the long-wave and short-wave radiative fluxes, which affect the surface temperature and may effect on the growth or retreat of sea ice extent and thickness. In this work, we exmine three-dimensional geometric and microphysical properties of Arctic clouds mainly from 8-year space-borne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR). Cloud Frations (CFs) from CALIOP-CPR and MODIS show similar seasonal and inter-annual variations, but shows significant different in CF over the opened sea area (i.e., Barents and Kara Sea) and over the sea ice. High occurrences of cloud top height are found below 2 km. But comparably high presences of mid- and high-level clouds are also found, especially in winter-time. This suggests that both low- and high-level clouds over the Arctic may influence on the long-wave radiation budget both at the surface and top of the atmosphere. On the other hand, the top height of winter-time clouds looks consistent with tropopause height. Cloud Optical Depth (COD) over the Arctic shows high in summer and low in winter, which would be contrary to the seasonal/monthly variations of CF. High COD during summer can be explained by enhanced level of liquid cloud droplet number concentrations. The number concentration and effective radius (in parenthesis) of liquid cloud droplet during summner was in the range of about 30 to 80 cm-3 (about 6 ~ 16 mm).

  4. Software Radar signal processing

    OpenAIRE

    T. Grydeland; Lind, F. D.; Erickson, P J; J. M. Holt

    2005-01-01

    Software infrastructure is a growing part of modern radio science systems. As part of developing a generic infrastructure for implementing Software Radar systems, we have developed a set of reusable signal processing components. These components are generic software-based implementations for use on general purpose computing systems. The components allow for the implementation of signal processing chains for radio frequency signal reception, correlation-based data processing, and cross-correla...

  5. Introduction to radar target recognition

    CERN Document Server

    Tait, P

    2006-01-01

    This new text provides an overview of the radar target recognition process and covers the key techniques being developed for operational systems. It is based on the fundamental scientific principles of high resolution radar, and explains how the techniques can be used in real systems, taking into account the characteristics of practical radar system designs and component limitations. It also addresses operational aspects, such as how high resolution modes would fit in with other functions such as detection and tracking. Mathematics is kept to a minimum and the complex techniques and issues are

  6. Rain radar instrument definition

    Science.gov (United States)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  7. RADAR PPI Scope Overlay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — RADAR PPI Scope Overlays are used to position a RADAR image over a station at the correct resolution. The archive maintains several different RADAR resolution...

  8. Multi-DSP and FPGA based Multi-channel Direct IF/RF Digital receiver for atmospheric radar

    Science.gov (United States)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kamaraj, Pandian; Durga rao, Meka; Thriveni, A.

    2016-07-01

    to DDC block, which down converts the data to base-band. The DDC block has NCO, mixer and two chains of Bessel filters (fifth order cascaded integration comb filter, two FIR filters, two half band filters and programmable FIR filters) for in-phase (I) and Quadrature phase (Q) channels. The NCO has 32 bits and is set to match the output frequency of ADC. Further, DDC down samples (decimation) the data and reduces the data rate to 16 MSPS. This data is further decimated and the data rate is reduced down to 4/2/1/0.5/0.25/0.125/0.0625 MSPS for baud lengths 0.25/0.5/1/2/4/8/16 μs respectively. The down sampled data is then fed to decoding block, which performs cross correlation to achieve pulse compression of the binary-phase coded data to obtain better range resolution with maximum possible height coverage. This step improves the signal power by a factor equal to the length of the code. Coherent integration block integrates the decoded data coherently for successive pulses, which improves the signal to noise ratio and reduces the data volume. DDC, decoding and coherent integration blocks are implemented in Xilinx vertex5 FPGA. Till this point, function of all six channels is same for DBS mode and multi-receiver modes. Data from vertex5 FPGA is transferred to PC via GbE-1 interface for multi-modes or to two Analog devices make ADSP-TS201 DSP chips (A and B), via link port for DBS mode. ADSP-TS201 chips perform the normalization, DC removal, windowing, FFT computation and spectral averaging on the data, which is transferred to storage/display PC via GbE-2 interface for real-time data display and data storing. Physical layer of GbE interface is implemented in an external chip (Marvel 88E1111) and MAC layer is implemented internal to vertex5 FPGA. The MCDRx has total 4 GB of DDR2 memory for data storage. Spartan6 FPGA is used for generating timing signals, required for basic operation of the radar and testing of the MCDRx.

  9. All-optical bandwidth-tailorable radar

    CERN Document Server

    Zou, Weiwen; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2015-01-01

    Radar has been widely used in military, security, and rescue. Metamaterial cloak is employed in stealth targets to evade radar detection. Hence modern radar should be reconfigurable at multi-bands for detecting stealth targets, which might be realized based on microwave photonics. Here, we demonstrate an all-optical bandwidth-tailorable radar architecture. It is a coherent system utilizing one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates wideband linearly-chirped radar signal. The working bands can be flexibly tailored with desired bandwidth at user-preferred carrier frequency. After modulated onto the pre-chirped optical pulse, radar echoes are time-stretched and frequency-compressed by several times. The digitization becomes much easier without loss of detection ability. We believe that the demonstration can innovate the radar's architecture with ultra-high range resolution.

  10. Advances in bistatic radar

    CERN Document Server

    Willis, Nick

    2007-01-01

    Advances in Bistatic Radar updates and extends bistatic and multistatic radar developments since publication of Willis' Bistatic Radar in 1991. New and recently declassified military applications are documented. Civil applications are detailed including commercial and scientific systems. Leading radar engineers provide expertise to each of these applications. Advances in Bistatic Radar consists of two major sections: Bistatic/Multistatic Radar Systems and Bistatic Clutter and Signal Processing. Starting with a history update, the first section documents the early and now declassified military

  11. Radar sensing of polar regions

    International Nuclear Information System (INIS)

    In order to monitor ecological conditions, study the processes of energy and mass transfer, and predict climate in polar regions it is necessary to introduce modern means of remote sensing. This paper considers potential applications and presents results of remote sensing of the ocean surface, ice, and soil-vegetation ground cover in polar regions obtained by satellite and aircraft side-looking radar. Unlike optical systems, surface studies using radar systems are not limited by illumination, or restricted by clouds and fog. Interpretation of radar data was based on comparisons between the coefficients of inverse diffusion and direct measurements made at test sites. The structure of ocean waves is reflected in radar images, revealing processes such as surface currents, internal waves, eddies, and frontal zones. Control data have shown economic disasters such as oil spills and drifting pollutants from coastal cities into the sea. Prospects are presented for using radar sensing for resolving a number of scientific and practical problems for the study of ice in the Arctic Basin. Radar methods also permit the characterization of soil-vegetation ground cover. In regions intensively used for agriculture, geochemical processes taking place under the earth and on its surface affect the soil structure and dielectric permeability at the surface level, and are evident in radar images. Results are presented of studies aimed at tracking the processes of spring thaw, areas subject to thermal erosion, floods, and vegetation condition

  12. Produtos à base de plantas medicinais comercializados em Pernambuco - Nordeste do Brasil

    OpenAIRE

    Nascimento, Joao Eudes do; Uchôa Lacerda, Erlandson; Teixeira do Nascimento, Viviany; Melo, Joabe Gomes de; Souza Alves, Bruno de; Melo e Silva, Luis Gustavo de; Alves Ramos, Marcelo; Sampaio de Andrade Lima, Claudia; de Albuquerque, Ulysses Paulino; Cavalcanti de Amorim, Elba Lúcia

    2005-01-01

    No Brasil existe um mercado sólido e crescente de produtos à base de plantas medicinais. Além das tradicionais ervarias, produtos industriais são vendidos livremente em drogarias e supermercados. Este estudo se propõe a realizar uma análise exploratória sobre os produtos à base de plantas comercializados em drogarias da cidade do Recife - estado de Pernambuco, Nordeste do Brasil. Em 54 estabelecimentos de duas grandes redes foi realizada coleta de dados com preenchimento de um formulário padr...

  13. Island based radar and microwave radiometer measurements of stratus cloud parameters during the Atlantic Stratocumulus Transition Experiment (ASTEX)

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, A.S. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C.W.; Snider, J.B. [NOAA Environmental Technology Lab., Boulder, CO (United States); Lenshow, D.H.; Mayer, S.D. [National Center for Atmospheric Research, Boulder, CO (United States)

    1996-04-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, simultaneous measurements were made with a vertically pointing cloud sensing radar and a microwave radiometer. The radar measurements are used to estimate stratus cloud drizzle and turbulence parameters. In addition, with the microwave radiometer measurements of reflectivity, we estimated the profiles of cloud liquid water and effective radius. We used radar data for computation of vertical profiles of various drizzle parameters such as droplet concentration, modal radius, and spread. A sample of these results is shown in Figure 1. In addition, in non-drizzle clouds, with the radar and radiometer we can estimate the verticle profiles of stratus cloud parameters such as liquid water concentration and effective radius. This is accomplished by assuming a droplet distribution with droplet number concentration and width constant with height.

  14. The NASA Polarimetric Radar (NPOL)

    Science.gov (United States)

    Petersen, Walter A.; Wolff, David B.

    2013-01-01

    Characteristics of the NASA NPOL S-band dual-polarimetric radar are presented including its operating characteristics, field configuration, scanning capabilities and calibration approaches. Examples of precipitation science data collections conducted using various scan types, and associated products, are presented for different convective system types and previous field campaign deployments. Finally, the NASA NPOL radar location is depicted in its home base configuration within the greater Wallops Flight Facility precipitation research array supporting NASA Global Precipitation Measurement Mission ground validation.

  15. A radar-based regional extreme rainfall analysis to derive the thresholds for a novel automatic alert system in Switzerland

    Science.gov (United States)

    Panziera, Luca; Gabella, Marco; Zanini, Stefano; Hering, Alessandro; Germann, Urs; Berne, Alexis

    2016-06-01

    This paper presents a regional extreme rainfall analysis based on 10 years of radar data for the 159 regions adopted for official natural hazard warnings in Switzerland. Moreover, a nowcasting tool aimed at issuing heavy precipitation regional alerts is introduced. The two topics are closely related, since the extreme rainfall analysis provides the thresholds used by the nowcasting system for the alerts. Warm and cold seasons' monthly maxima of several statistical quantities describing regional rainfall are fitted to a generalized extreme value distribution in order to derive the precipitation amounts corresponding to sub-annual return periods for durations of 1, 3, 6, 12, 24 and 48 h. It is shown that regional return levels exhibit a large spatial variability in Switzerland, and that their spatial distribution strongly depends on the duration of the aggregation period: for accumulations of 3 h and shorter, the largest return levels are found over the northerly alpine slopes, whereas for longer durations the southern Alps exhibit the largest values. The inner alpine chain shows the lowest values, in agreement with previous rainfall climatologies. The nowcasting system presented here is aimed to issue heavy rainfall alerts for a large variety of end users, who are interested in different precipitation characteristics and regions, such as, for example, small urban areas, remote alpine catchments or administrative districts. The alerts are issued not only if the rainfall measured in the immediate past or forecast in the near future exceeds some predefined thresholds but also as soon as the sum of past and forecast precipitation is larger than threshold values. This precipitation total, in fact, has primary importance in applications for which antecedent rainfall is as important as predicted one, such as urban floods early warning systems. The rainfall fields, the statistical quantity representing regional rainfall and the frequency of alerts issued in case of

  16. Testbed for development of a DSP-based signal processing subsystem for an Earth-orbiting radar scatterometer

    Science.gov (United States)

    Clark, Douglas J.; Lux, James P.; Shirbacheh, Mike

    2002-01-01

    A testbed for evaluation of general-purpose digital signal processors in earth-orbiting radar scatterometers is discussed. Because general purpose DSP represents a departure from previous radar signal processing techniques used on scatterometers, there was a need to demonstrate key elements of the system to verify feasibility for potential future scatterometer instruments. Construction of the testbed also facilitated identification of an appropriate software development environment and the skills mix necessary to perform the work.

  17. Two-Dimensional Direction-of-Arrival Estimation for Trilinear Decomposition-Based Monostatic Cross MIMO Radar

    OpenAIRE

    Fangqing Wen; Gong Zhang

    2013-01-01

    A low complexity monostatic cross multiple-in multiple-out (MIMO) radar scheme is proposed in this paper. The minimum-redundancy linear array (MRLA) is introduced in the cross radar to improve the efficiency of the array elements. The two-dimensional direction-of-arrival (DOA) estimation problem links to the trilinear model, which automatically pairs the estimated two-dimensional angles, requiring neither eigenvalue decomposition of received signal covariance matrix nor spectral peak searchin...

  18. Applicability of Doppler weather radar based rainfall data for runoff estimation in Indian watersheds – A case study of Chennai basin

    Indian Academy of Sciences (India)

    V S Josephine; B V Mudgal; S B Thampi

    2014-08-01

    Traditionally, India has been vulnerable to various hazards such as floods, droughts and cyclones. About 8% of the total Indian landmass is prone to cyclones. A number of Doppler weather radars are installed in India and their products are utilized for weather predictions and detection of cyclones approaching the Indian coast. Radar-based hydrological studies in various countries have proven that computation of runoff using radar rainfall data could outperform rain gauge network measurements. There are no reported studies on their utilization for hydrological modelling and/or flood-related studies in Indian river basins. A comparison study between Doppler weather radar (DWR) derived rainfall data and the conventional rain gauge data was carried out with hourly inputs at one of the watersheds of Chennai basin, Tamil Nadu, India using HEC-HMS model. The model calibration and validation were performed by comparing the simulated outflow with the observed daily outflow data. The calibrated model was used to predict runoff from two post-monsoon cyclonic storm events with hourly inputs. It was noticed that the discrepancy in the runoff volume was small, but the difference in the peak flow was substantial. Additionally, there was a variation at the time to peak flow using daily and hourly inputs. The results show that the use of radar data may be optional for runoff volume estimation for the watersheds with sufficient rain gauge density, but highly desirable for peak flow and time to peak estimation. Therefore, the DWR derived rainfall data is a promising input for runoff estimation, especially in urban flood modelling.

  19. Compressive Sensing for MIMO Radar

    CERN Document Server

    Yu, Yao; Poor, H Vincent

    2009-01-01

    Multiple-input multiple-output (MIMO) radar systems have been shown to achieve superior resolution as compared to traditional radar systems with the same number of transmit and receive antennas. This paper considers a distributed MIMO radar scenario, in which each transmit element is a node in a wireless network, and investigates the use of compressive sampling for direction-of-arrival (DOA) estimation. According to the theory of compressive sampling, a signal that is sparse in some domain can be recovered based on far fewer samples than required by the Nyquist sampling theorem. The DOA of targets form a sparse vector in the angle space, and therefore, compressive sampling can be applied for DOA estimation. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than other approaches. This is particularly useful in a distributed scenario, in which the results at each receive node need to be transmitted to a fusion center for further processing.

  20. Volcanic Ash Cloud Observation using Ground-based Ka-band Radar and Near-Infrared Lidar Ceilometer during the Eyjafjallajökull eruption

    Directory of Open Access Journals (Sweden)

    Frank S. Marzano

    2015-03-01

    Full Text Available Active remote sensing techniques can probe volcanic ash plumes, but their sensitivity at a given distance depends upon the sensor transmitted power, wavelength and polarization capability. Building on a previous numerical study at centimeter wavelength, this work aims at i simulating the distal ash particles polarimetric response of millimeter-wave radar and multi-wavelength optical lidar; ii developing and applying a model-based statistical retrieval scheme using a multi-sensor approach. The microphysical electromagnetic forward model of volcanic ash particle distribution, previously set up at microwaves, is extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena for both millimeter and optical bands. Monte Carlo generation of radar and lidar signatures are driven by random variability of volcanic particle main parameters, using constraints from available data and experimental evidences. The considered case study is related to the ground-based observation of the Eyjafjallajökull (Iceland volcanic ash plume on May 15, 2010, carried out by the Atmospheric Research Station at Mace Head (Ireland with a 35-GHz Ka-band Doppler cloud radar and a 1064-nm ceilometer lidar. The detection and estimation of ash layer presence and composition is carried out using a Bayesian approach, which is trained by the Monte Carlo model-based dataset. Retrieval results are corroborated exploiting auxiliary data such as those from a ground-based microwave radiometer also positioned at Mace Head.

  1. Prototyping a GNSS-Based Passive Radar for UAVs: An Instrument to Classify the Water Content Feature of Lands

    Science.gov (United States)

    Troglia Gamba, Micaela; Marucco, Gianluca; Pini, Marco; Ugazio, Sabrina; Falletti, Emanuela; Lo Presti, Letizia

    2015-01-01

    Global Navigation Satellite Systems (GNSS) broadcast signals for positioning and navigation, which can be also employed for remote sensing applications. Indeed, the satellites of any GNSS can be seen as synchronized sources of electromagnetic radiation, and specific processing of the signals reflected back from the ground can be used to estimate the geophysical properties of the Earth’s surface. Several experiments have successfully demonstrated GNSS-reflectometry (GNSS-R), whereas new applications are continuously emerging and are presently under development, either from static or dynamic platforms. GNSS-R can be implemented at a low cost, primarily if small devices are mounted on-board unmanned aerial vehicles (UAVs), which today can be equipped with several types of sensors for environmental monitoring. So far, many instruments for GNSS-R have followed the GNSS bistatic radar architecture and consisted of custom GNSS receivers, often requiring a personal computer and bulky systems to store large amounts of data. This paper presents the development of a GNSS-based sensor for UAVs and small manned aircraft, used to classify lands according to their soil water content. The paper provides details on the design of the major hardware and software components, as well as the description of the results obtained through field tests. PMID:26569242

  2. Prototyping a GNSS-Based Passive Radar for UAVs: An Instrument to Classify the Water Content Feature of Lands

    Directory of Open Access Journals (Sweden)

    Micaela Troglia Gamba

    2015-11-01

    Full Text Available Global Navigation Satellite Systems (GNSS broadcast signals for positioning and navigation, which can be also employed for remote sensing applications. Indeed, the satellites of any GNSS can be seen as synchronized sources of electromagnetic radiation, and specific processing of the signals reflected back from the ground can be used to estimate the geophysical properties of the Earth’s surface. Several experiments have successfully demonstrated GNSS-reflectometry (GNSS-R, whereas new applications are continuously emerging and are presently under development, either from static or dynamic platforms. GNSS-R can be implemented at a low cost, primarily if small devices are mounted on-board unmanned aerial vehicles (UAVs, which today can be equipped with several types of sensors for environmental monitoring. So far, many instruments for GNSS-R have followed the GNSS bistatic radar architecture and consisted of custom GNSS receivers, often requiring a personal computer and bulky systems to store large amounts of data. This paper presents the development of a GNSS-based sensor for UAVs and small manned aircraft, used to classify lands according to their soil water content. The paper provides details on the design of the major hardware and software components, as well as the description of the results obtained through field tests.

  3. Prototyping a GNSS-Based Passive Radar for UAVs: An Instrument to Classify the Water Content Feature of Lands.

    Science.gov (United States)

    Gamba, Micaela Troglia; Marucco, Gianluca; Pini, Marco; Ugazio, Sabrina; Falletti, Emanuela; Lo Presti, Letizia

    2015-01-01

    Global Navigation Satellite Systems (GNSS) broadcast signals for positioning and navigation, which can be also employed for remote sensing applications. Indeed, the satellites of any GNSS can be seen as synchronized sources of electromagnetic radiation, and specific processing of the signals reflected back from the ground can be used to estimate the geophysical properties of the Earth's surface. Several experiments have successfully demonstrated GNSS-reflectometry (GNSS-R), whereas new applications are continuously emerging and are presently under development, either from static or dynamic platforms. GNSS-R can be implemented at a low cost, primarily if small devices are mounted on-board unmanned aerial vehicles (UAVs), which today can be equipped with several types of sensors for environmental monitoring. So far, many instruments for GNSS-R have followed the GNSS bistatic radar architecture and consisted of custom GNSS receivers, often requiring a personal computer and bulky systems to store large amounts of data. This paper presents the development of a GNSS-based sensor for UAVs and small manned aircraft, used to classify lands according to their soil water content. The paper provides details on the design of the major hardware and software components, as well as the description of the results obtained through field tests. PMID:26569242

  4. Airborne derivation of microburst alerts from ground-based Terminal Doppler Weather Radar information: A flight evaluation

    Science.gov (United States)

    Hinton, David A.

    1993-01-01

    An element of the NASA/FAA windshear program is the integration of ground-based microburst information on the flight deck, to support airborne windshear alerting and microburst avoidance. NASA conducted a windshear flight test program in the summer of 1991 during which airborne processing of Terminal Doppler Weather Radar (TDWR) data was used to derive microburst alerts. Microburst information was extracted from TDWR, transmitted to a NASA Boeing 737 in flight via data link, and processed to estimate the windshear hazard level (F-factor) that would be experienced by the aircraft in each microburst. The microburst location and F-factor were used to derive a situation display and alerts. The situation display was successfully used to maneuver the aircraft for microburst penetrations, during which atmospheric 'truth' measurements were made. A total of 19 penetrations were made of TDWR-reported microburst locations, resulting in 18 airborne microburst alerts from the TDWR data and two microburst alerts from the airborne reactive windshear detection system. The primary factors affecting alerting performance were spatial offset of the flight path from the region of strongest shear, differences in TDWR measurement altitude and airplane penetration altitude, and variations in microburst outflow profiles. Predicted and measured F-factors agreed well in penetrations near microburst cores. Although improvements in airborne and ground processing of the TDWR measurements would be required to support an airborne executive-level alerting protocol, the practicality of airborne utilization of TDWR data link data has been demonstrated.

  5. Parameterizing road construction in route-based road weather models: can ground-penetrating radar provide any answers?

    International Nuclear Information System (INIS)

    A ground-penetrating radar (GPR) survey of a 32 km mixed urban and rural study route is undertaken to assess the usefulness of GPR as a tool for parameterizing road construction in a route-based road weather forecast model. It is shown that GPR can easily identify even the smallest of bridges along the route, which previous thermal mapping surveys have identified as thermal singularities with implications for winter road maintenance. Using individual GPR traces measured at each forecast point along the route, an inflexion point detection algorithm attempts to identify the depth of the uppermost subsurface layers at each forecast point for use in a road weather model instead of existing ordinal road-type classifications. This approach has the potential to allow high resolution modelling of road construction and bridge decks on a scale previously not possible within a road weather model, but initial results reveal that significant future research will be required to unlock the full potential that this technology can bring to the road weather industry. (technical design note)

  6. Full-polarization radar remote sensing and data mining for tropical crops mapping: a successful SVM-based classification model

    Science.gov (United States)

    Denize, J.; Corgne, S.; Todoroff, P.; LE Mezo, L.

    2015-12-01

    In Reunion, a tropical island of 2,512 km², 700 km east of Madagascar in the Indian Ocean, constrained by a rugged relief, agricultural sectors are competing in highly fragmented agricultural land constituted by heterogeneous farming systems from corporate to small-scale farming. Policymakers, planners and institutions are in dire need of reliable and updated land use references. Actually conventional land use mapping methods are inefficient under the tropic with frequent cloud cover and loosely synchronous vegetative cycles of the crops due to a constant temperature. This study aims to provide an appropriate method for the identification and mapping of tropical crops by remote sensing. For this purpose, we assess the potential of polarimetric SAR imagery associated with associated with machine learning algorithms. The method has been developed and tested on a study area of 25*25 km thanks to 6 RADARSAT-2 images in 2014 in full-polarization. A set of radar indicators (backscatter coefficient, bands ratios, indices, polarimetric decompositions (Freeman-Durden, Van zyl, Yamaguchi, Cloude and Pottier, Krogager), texture, etc.) was calculated from the coherency matrix. A random forest procedure allowed the selection of the most important variables on each images to reduce the dimension of the dataset and the processing time. Support Vector Machines (SVM), allowed the classification of these indicators based on a learning database created from field observations in 2013. The method shows an overall accuracy of 88% with a Kappa index of 0.82 for the identification of four major crops.

  7. The Simultaneous Interpolation of Target Radar Cross Section in Both the Spatial and Frequency Domains by Means of Legendre Wavelets Model-Based Parameter Estimation

    Directory of Open Access Journals (Sweden)

    Yongqiang Yang

    2015-01-01

    Full Text Available The understanding of the target radar cross section (RCS is significant for target identification and for radar designing and optimization. In this paper, a numerical algorithm for calculating target RCS is presented which is based on Legendre wavelet model-based parameter estimation (LW-MBPE. The Padé rational function fitting model applied for MBPE in the frequency domain is enhanced to include spatial dependence on the numerator and denominator coefficients. This allows the function to interpolate target RCS in both the frequency and spatial domains simultaneously. The combination of Legendre wavelets guarantees the convergence of the algorithm. The method is convergent by increasing the sampling frequency and spatial points. Numerical results are provided to demonstrate the validity and applicability of the new technique.

  8. Radar and Lidar Radar DEM

    Science.gov (United States)

    Liskovich, Diana; Simard, Marc

    2011-01-01

    Using radar and lidar data, the aim is to improve 3D rendering of terrain, including digital elevation models (DEM) and estimates of vegetation height and biomass in a variety of forest types and terrains. The 3D mapping of vegetation structure and the analysis are useful to determine the role of forest in climate change (carbon cycle), in providing habitat and as a provider of socio-economic services. This in turn will lead to potential for development of more effective land-use management. The first part of the project was to characterize the Shuttle Radar Topography Mission DEM error with respect to ICESat/GLAS point estimates of elevation. We investigated potential trends with latitude, canopy height, signal to noise ratio (SNR), number of LiDAR waveform peaks, and maximum peak width. Scatter plots were produced for each variable and were fitted with 1st and 2nd degree polynomials. Higher order trends were visually inspected through filtering with a mean and median filter. We also assessed trends in the DEM error variance. Finally, a map showing how DEM error was geographically distributed globally was created.

  9. Aspects of Applying Weather Radar-Based Nowcasts of Rainfall for Highways in Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Thorndahl, Søren Liedtke; Quist, M.

    2012-01-01

    This work investigates three different approaches to nowcasting rainfall for highways. The simplest method is based on using the observed precipitation field at the beginning of the trip. The most developed nowcast is based on a COTREC nowcaster, which is dynamically adjusted to online raingauges...

  10. EM-Based Optimization Exploiting Partial Space Mapping and Exact Sensitivities

    DEFF Research Database (Denmark)

    Bandler, J. W.; Mohamed, A. S.; Bakr, M. H.;

    2002-01-01

    We present a family of robust techniques for exploiting sensitivities in EM-based circuit optimization through Space Mapping (SM). We utilize derivative Information for parameter extractions and mapping updates. We exploit a Partial Space Mapping (PSM) concept where a reduced set of parameters...... is sufficient for parameter extraction optimization. Upfront gradients of both EM (fine) model and coarse surrogates can initialize possible mapping approximations. Illustrations include a two-section 10:1 impedance transformer and a microstrip bandstop filter....

  11. EM-Based Optimization Exploiting Partial Space Mapping and Exact Sensitivities

    DEFF Research Database (Denmark)

    Bandler, J. W.; Mohamed, A. S.; Bakr, M. H.; Madsen, Kaj; Søndergaard, Jacob

    We present a family of robust techniques for exploiting sensitivities in EM-based circuit optimization through Space Mapping (SM). We utilize derivative Information for parameter extractions and mapping updates. We exploit a Partial Space Mapping (PSM) concept where a reduced set of parameters is...... sufficient for parameter extraction optimization. Upfront gradients of both EM (fine) model and coarse surrogates can initialize possible mapping approximations. Illustrations include a two-section 10:1 impedance transformer and a microstrip bandstop filter....

  12. Recent Developments in Radar Waveforms (in English)

    OpenAIRE

    Cao Si-yang; Zheng Yuan-fang

    2014-01-01

    With the development of high speed digital processor and solid state power electronics, more flexible waveforms become feasible to achieve by modern radar systems. In fact, the choice of waveforms has a significant impact on the performance of radar systems. In this paper, we review the conventional radar waveform design as well as explore the new generation of waveforms via different theoretical methods, including the most recent wavelet based waveforms. It is shown that the waveform design ...

  13. Compressed Sensing Applied to Weather Radar

    OpenAIRE

    Mishra, Kumar Vijay; Kruger, Anton; Krajewski, Witold F.

    2014-01-01

    We propose an innovative meteorological radar, which uses reduced number of spatiotemporal samples without compromising the accuracy of target information. Our approach extends recent research on compressed sensing (CS) for radar remote sensing of hard point scatterers to volumetric targets. The previously published CS-based radar techniques are not applicable for sampling weather since the precipitation echoes lack sparsity in both range-time and Doppler domains. We propose an alternative ap...

  14. A Knowledge Based Expert-System For Synthetic Aperture Radar Target Recognition

    Science.gov (United States)

    Rogers, Steven K.; Kabrisky, Matthew; Anderson, Steven; Mills, James P.

    1988-03-01

    This paper describes a knowledge-based expert system that uses return features, provided by image analysts, to identify an object as a specific instance or class of object, such as a tank or truck. Partial feature sets allow the expert system to classify occluded and unfamiliar or falsified object data returns to the most likely class with a specified reasoning path. The rule based system was developed using the Prolog version of Ml.

  15. Bases da terapia celular em cardiologia Cell therapy in cardiology

    OpenAIRE

    Antonio Carlos C. Carvalho; Regina Coeli S. Goldenberg; Fábio Antonio A. Tuche; Hans Fernando R. Dohmann

    2009-01-01

    O implante de células para o tratamento de doenças cardiovasculares encontra-se sob investigação em vários centros no mundo. Várias linhagens celulares, de células-tronco bem caracterizadas a frações contendo diferentes tipos de células, têm sido investigadas em modelos animais. Apesar dos avanços obtidos na última década, na área de ciência básica, com relação a esta nova modalidade terapêutica, diversas questões permanecem sem resposta. Pouco ainda se sabe sobre os mecanismos através dos qu...

  16. Hydrologic applications of weather radar

    Science.gov (United States)

    Seo, Dong-Jun; Habib, Emad; Andrieu, Hervé; Morin, Efrat

    2015-12-01

    By providing high-resolution quantitative precipitation information (QPI), weather radars have revolutionized hydrology in the last two decades. With the aid of GIS technology, radar-based quantitative precipitation estimates (QPE) have enabled routine high-resolution hydrologic modeling in many parts of the world. Given the ever-increasing need for higher-resolution hydrologic and water resources information for a wide range of applications, one may expect that the use of weather radar will only grow. Despite the tremendous progress, a number of significant scientific, technological and engineering challenges remain to realize its potential. New challenges are also emerging as new areas of applications are discovered, explored and pursued. The purpose of this special issue is to provide the readership with some of the latest advances, lessons learned, experiences gained, and science issues and challenges related to hydrologic applications of weather radar. The special issue features 20 contributions on various topics which reflect the increasing diversity as well as the areas of focus in radar hydrology today. The contributions may be grouped as follows: Radar QPE (Kwon et al.; Hall et al.; Chen and Chandrasekar; Seo and Krajewski; Sandford).

  17. Gravimetric Radar: Gravity-Based Detection of a Point-Mass Moving in a Static Background

    CERN Document Server

    Tannenbaum, Emmanuel David

    2012-01-01

    This paper discusses a novel approach for detecting moving massive objects based on the time variation that these objects produce in the local gravitational field measured by several detectors. Such an approach may provide a viable method for detecting stealth aircraft, UAVs, cruise, and ballistic missiles. By inverting a set of nonlinear algebraic equations, it is possible to use the time variation in the gravitational fields to compute the mass, position, and velocity of one or more moving objects. The approach is essentially a gravity-based form of triangulation. Based on order-of-magnitude calculations, we estimate that under realistic scenarios, this approach will be feasible if it is possible to design gravimetric devices that are four to five order of magnitude more sensitive than current devices. To achieve such a level of sensitivity, we suggest designing detectors that exploit a quantum-mechanical effect known as gravity-induced quantum interference. Furthermore, even if we have a perfect detector, ...

  18. Validation of Satellite-Based Objective Overshooting Cloud-Top Detection Methods Using CloudSat Cloud Profiling Radar Observations

    Science.gov (United States)

    Bedka, Kristopher M.; Dworak, Richard; Brunner, Jason; Feltz, Wayne

    2012-01-01

    Two satellite infrared-based overshooting convective cloud-top (OT) detection methods have recently been described in the literature: 1) the 11-mm infrared window channel texture (IRW texture) method, which uses IRW channel brightness temperature (BT) spatial gradients and thresholds, and 2) the water vapor minus IRW BT difference (WV-IRW BTD). While both methods show good performance in published case study examples, it is important to quantitatively validate these methods relative to overshooting top events across the globe. Unfortunately, no overshooting top database currently exists that could be used in such study. This study examines National Aeronautics and Space Administration CloudSat Cloud Profiling Radar data to develop an OT detection validation database that is used to evaluate the IRW-texture and WV-IRW BTD OT detection methods. CloudSat data were manually examined over a 1.5-yr period to identify cases in which the cloud top penetrates above the tropopause height defined by a numerical weather prediction model and the surrounding cirrus anvil cloud top, producing 111 confirmed overshooting top events. When applied to Moderate Resolution Imaging Spectroradiometer (MODIS)-based Geostationary Operational Environmental Satellite-R Series (GOES-R) Advanced Baseline Imager proxy data, the IRW-texture (WV-IRW BTD) method offered a 76% (96%) probability of OT detection (POD) and 16% (81%) false-alarm ratio. Case study examples show that WV-IRW BTD.0 K identifies much of the deep convective cloud top, while the IRW-texture method focuses only on regions with a spatial scale near that of commonly observed OTs. The POD decreases by 20% when IRW-texture is applied to current geostationary imager data, highlighting the importance of imager spatial resolution for observing and detecting OT regions.

  19. Mapping plasma structures in the high-latitude ionosphere using beacon satellite, incoherent scatter radar and ground-based magnetometer observations

    Directory of Open Access Journals (Sweden)

    T. Neubert

    2002-06-01

    Full Text Available In the autumn of the year 2000, four radio receivers capable of tracking various beacon satellites were set up along the southwestern coast of Greenland. They are used to reconstruct images of the ionospheric plasma density distribution via the tomographic method. In order to test and validate tomographic imaging under the highly variable conditions often prevailing in the high-latitude ionosphere, a time interval was selected when the Sondrestrom incoherent scatter radar conducted measurements of the ionospheric plasma density while the radio receivers tracked a number of beacon satellites. A comparison between two-dimensional images of the plasma density distribution obtained from the radar and the satellite receivers revealed generally good agreement between radar measurements and tomographic images. Observed discrepancies can be attributed to F region plasma patches moving through the field of view with a speed of several hundred meters per second, thereby smearing out the tomographic image. A notable mismatch occurred around local magnetic midnight when a magnetospheric substorm breakup occurred in the vicinity of southwest Greenland (identified from ground-based magnetometer observations. The breakup was associated with a sudden intensification of the westward auroral electrojet which was centered at about 69 and extended up to some 73 corrected geomagnetic latitude. Ground-based magnetometer data may thus have the potential of indicating when the tomographic method is at risk and may fail. We finally outline the application of tomographic imaging, when combined with magnetic field data, to estimate ionospheric Joule heating rates.

  20. A grid-based distributed flood forecasting model for use with weather radar data: Part 1. Formulation

    Directory of Open Access Journals (Sweden)

    V. A. Bell

    1998-01-01

    Full Text Available A practical methodology for distributed rainfall-runoff modelling using grid square weather radar data is developed for use in real-time flood forecasting. The model, called the Grid Model, is configured so as to share the same grid as used by the weather radar, thereby exploiting the distributed rainfall estimates to the full. Each grid square in the catchment is conceptualised as a storage which receives water as precipitation and generates water by overflow and drainage. This water is routed across the catchment using isochrone pathways. These are derived from a digital terrain model assuming two fixed velocities of travel for land and river pathways which are regarded as model parameters to be optimised. Translation of water between isochrones is achieved using a discrete kinematic routing procedure, parameterised through a single dimensionless wave speed parameter, which advects the water and incorporates diffusion effects through the discrete space-time formulation. The basic model routes overflow and drainage separately through a parallel system of kinematic routing reaches, characterised by different wave speeds but using the same isochrone-based space discretisation; these represent fast and slow pathways to the basin outlet, respectively. A variant allows the slow pathway to have separate isochrones calculated using Darcy velocities controlled by the hydraulic gradient as estimated by the local gradient of the terrain. Runoff production within a grid square is controlled by its absorption capacity which is parameterised through a simple linkage function to the mean gradient in the square, as calculated from digital terrain data. This allows absorption capacity to be specified differently for every grid square in the catchment through the use of only two regional parameters and a DTM measurement of mean gradient for each square. An extension of this basic idea to consider the distribution of gradient within the square leads analytically

  1. Preâmbulo [a] "Data mining : descoberta de conhecimento em bases de dados"

    OpenAIRE

    Santos, Manuel Filipe; Azevedo, Carla Sousa

    2005-01-01

    As áreas de Descoberta de Conhecimento em Bases de Dados e Data Mining estão em grande evolução e expansão, atraindo cada vez mais interessados, como se comprova pelos projectos em desenvolvimento, os grupos de investigação, os seminários, conferências e publicações. Esta evolução tem suporte na premissa de que os grandes volumes de dados disponíveis podem ser fonte de conhecimento útil e com aplicabilidade em diversos domínios. Surgem, a todo o momento, novos modelos e técnicas, com maiores ...

  2. The Bayesian Reliability Assessment and Prediction for Radar System Based on New Dirichlet Prior Distribution

    Science.gov (United States)

    Ming, Zhimao; Ling, Xiaodong; Bai, Xiaoshu; Zong, Bo

    2016-02-01

    This article studies on Bayesian reliability growth models of complex system based on new Dirichlet prior distribution when the sample of system is small. The model briefly describes expert experience as uniform distribution, then equivalent general Beta distribution of uniform distribution can be solved by optimization method when prior parameters are variables, mean is constraint condition, and variance is regarding as the optimization objective. The optimization method solves the problem of how to determine values of hyper-parameters of new Dirichlet distribution when these parameters have no specific physical meaning. Because the multidimensional numerical integration of posterior distribution is very difficult to calculate, WinBUGS software is employed to establish Bayesian reliability growth model based on a new Dirichlet prior distribution, and two practical cases are studied under this model in order to prove validity of model. The analysis results show that the model can improve the precision of calculation, and it is easy to use in engineering.

  3. Ray tracing/correlation approach to estimation of surface-based duct parameters from radar clutter

    International Nuclear Information System (INIS)

    This paper describes a technique to estimate surface-based duct parameters by using a simple ray tracing/correlation method. The approach is novel in that it incorporates the Spearman rank-order correlation scheme between the observed surface clutter and the surface ray density for a given propagation path. The simulation results and the real data results both demonstrate the ability of this method to estimate surface-based duct parameters. Compared with the results obtained by a modified genetic algorithm combined with the parabolic wave equation, the results retrieved from the ray tracing/correlation scheme show a minor reduction in accuracy but a great improvement on computation time. Therefore the ray tracing/correlation method might be used as a precursor to more sophisticated and slower techniques, such as genetic algorithm and particle filters, by narrowing the parameter search space and providing a comprehensive and more efficient estimation algorithm. (geophysics, astronomy and astrophysics)

  4. Wind estimation around the shipwreck of Oriental Star based on field damage surveys and radar observations

    OpenAIRE

    Meng, Zhiyong; Yao, Dan; Bai, Lanqiang; Zheng, Yongguang; Xue, Ming; Zhang, Xiaoling; Zhao, Kun; Tian, Fuyou; Wang, Mingjun

    2016-01-01

    Based on observational analyses and on-site ground and aerial damage surveys, this work aims to reveal the weather phenomena—especially the wind situation—when Oriental Star capsized in the Yangtze River on June 1, 2015. Results demonstrate that the cruise ship capsized when it encountered strong winds at speeds of at least 31 m s−1 near the apex of a bow echo embedded in a squall line. As suggested by the fallen trees within a 2-km radius around the wreck location, such strong winds were lik...

  5. Dwell scheduling algorithm for multifunction phased array radars based on the scheduling gain

    Institute of Scientific and Technical Information of China (English)

    Cheng Ting; He Zishu; Tang Ting

    2008-01-01

    A real-time dwell scheduling model, which takes the time and energy constraints into account is founded from the viewpoint of scheduling gain. Scheduling design is turned into a nonlinear programming procedure. The real-time dwell scheduling algorithm based on the scheduling gain is presented with the help of two heuristic rules. The simulation results demonstrate that compared with the conventional adaptive scheduling method, the algorithm proposed not only increases the scheduling gain and the time utility but also decreases the task drop rate.

  6. Consumo de nutrientes em adultos e idosos em estudo de base populacional: Projeto Bambuí

    Directory of Open Access Journals (Sweden)

    Aline Cristine Souza Lopes

    2005-08-01

    Full Text Available Inquérito alimentar populacional em amostra aleatória de 550 indivíduos > ou = 18 anos, realizado em Bambuí, Minas Gerais, Brasil, utilizando o Questionário Semiquantitativo de Freqüência Alimentar e recordatório 24 horas calibrados pela técnica de regressão linear. A análise constou de comparação de médias, teste de qui-quadrado e razão de adequação do nutriente (RAN-adequada: 90,0-110,0%. Foi baixo o percentual da população que apresentou RAN de acordo com o recomendado para consumo de carboidratos (2,4%, proteínas (17,6%, vitaminas (0,0-5,1% e minerais (0-21,1%. Diferenças de acordo com sexo e idade foram encontradas: 90,2% e 91,8% de mulheres apresentaram baixo consumo de ferro e vitamina B6, respectivamente. Ao contrário, 87,7% dos homens relataram consumo excessivo de ferro, 80,3% de fósforo e 11,9% de colesterol. Quanto à idade, 64,3% de idosos (> 60 anos relataram baixa ingestão protéica e 39,3% apresentavam inadequação das frações lipídicas; sendo que 35,7% informaram consumo excessivo de ácidos graxos saturados. Dos adultos (18-59 anos, 67,8% relataram excessivo consumo protéico e 53,4% ingestão insuficiente de ferro. Alto e inadequado consumo de lipídios e baixa ingestão de fibras, vitaminas e minerais, constituem problema importante de saúde pública por possivelmente contribuir para o aumento das doenças crônicas não transmissíveis.

  7. Bases da terapia celular em cardiologia Cell therapy in cardiology

    Directory of Open Access Journals (Sweden)

    Antonio Carlos C. Carvalho

    2009-05-01

    Full Text Available O implante de células para o tratamento de doenças cardiovasculares encontra-se sob investigação em vários centros no mundo. Várias linhagens celulares, de células-tronco bem caracterizadas a frações contendo diferentes tipos de células, têm sido investigadas em modelos animais. Apesar dos avanços obtidos na última década, na área de ciência básica, com relação a esta nova modalidade terapêutica, diversas questões permanecem sem resposta. Pouco ainda se sabe sobre os mecanismos através dos quais a terapia celular possa gerar resultados efetivos. Adicionalmente, a melhor via para o transplante, o número total e a concentração de células, e o melhor tipo celular permanecem questões importantes, ainda sem definição. É fato de que diversas células da medula óssea exercem seus efeitos através de mecanismos parácrinos e de que existe um complexo mecanismo de interação, contato e liberação de sinais entre essas células e as outras populações celulares nos órgãos lesados. Atualmente, a maioria dos estudos em humanos se concentra em células de origem adulta e autóloga, em oposição ao uso de células de origem embrionária. Esta revisão analisa os principais ensaios clínicos que utilizaram células derivadas de medula óssea em quatro cardiopatias: doença arterial coronariana aguda e crônica, e nas cardiomiopatias chagásica e dilatada. Os resultados desses estudos demonstram que o procedimento é seguro e exequível, e potencialmente eficaz. Inquestionavelmente, mais estudos pré-clínicos e clínicos são necessários para acessar o real potencial benefício desse novo modelo terapêutico.Cell transplantation for the treatment of cardiovascular diseases is being investigated in many centers throughout the world. Various cell lines, from well characterized stem cells to cell fractions containing different types of cells, have been investigated in animal models. Despite progress in the basic research of

  8. Radar hydrometeorology using a vertically pointing radar

    OpenAIRE

    Cluckie, I. D.; R. J. Griffith; Lane, A; Tilford, K. A.

    2002-01-01

    International audience A Vertically Pointing Radar (VPR) has been commissioned and deployed at a number of sites in southern England, to investigate numerically spatial and temporal variations in the vertical reflectivity profile (Zvp); particularly those associated with the intersection by the radar beam of a melting layer ? the bright band. Comparisons with data from other instrumentation, notably with the S-band research radar at Chilbolton, but also with disdrometer data and rainfall m...

  9. Radar hydrometeorology using a vertically pointing radar

    OpenAIRE

    Cluckie, I. D.; R. J. Griffith; Lane, A; Tilford, K. A.

    2000-01-01

    A Vertically Pointing Radar (VPR) has been commissioned and deployed at a number of sites in southern England, to investigate numerically spatial and temporal variations in the vertical reflectivity profile (Zvp); particularly those associated with the intersection by the radar beam of a melting layer – the bright band. Comparisons with data from other instrumentation, notably with the S-band research radar at Chilbolton, but also with disdrometer data and rainfall measurements from a number ...

  10. Adaptive radar resource management

    CERN Document Server

    Moo, Peter

    2015-01-01

    Radar Resource Management (RRM) is vital for optimizing the performance of modern phased array radars, which are the primary sensor for aircraft, ships, and land platforms. Adaptive Radar Resource Management gives an introduction to radar resource management (RRM), presenting a clear overview of different approaches and techniques, making it very suitable for radar practitioners and researchers in industry and universities. Coverage includes: RRM's role in optimizing the performance of modern phased array radars The advantages of adaptivity in implementing RRMThe role that modelling and

  11. Radar and ARPA manual

    CERN Document Server

    Bole, A G

    2013-01-01

    Radar and ARPA Manual focuses on the theoretical and practical aspects of electronic navigation. The manual first discusses basic radar principles, including principles of range and bearing measurements and picture orientation and presentation. The text then looks at the operational principles of radar systems. Function of units; aerial, receiver, and display principles; transmitter principles; and sitting of units on board ships are discussed. The book also describes target detection, Automatic Radar Plotting Aids (ARPA), and operational controls of radar systems, and then discusses radar plo

  12. Physically-based Flood Modeling Driven by Radar Rainfall in the Upper Guadalupe River Basin, Texas

    Science.gov (United States)

    Sharif, H. O.; Chintalapudi, S.; El Hassan, A.

    2011-12-01

    The upstream portion of the Guadalupe River Basin (Upper Guadalupe River Basin) is prone to frequent flooding due to its physiographic properties (thin soils, exposed bedrock, and sparse vegetation). The Upper Guadalupe River watershed above Comfort, Texas drains an area of 2,170 square kilometers. This watershed is located at the central part of the Texas Hill Country. This study presents hydrologic analysis of the June 2002, November-2004, and August-2007 flood events that occurred in Upper Guadalupe River Basin. The physically based, distributed-parameter Gridded Surface Subsurface Hydrologic Analysis (GSSHA) hydrologic model was used to simulate the above flooding events. The first event was used in model while the other two were used for validation. GSSHA model was driven by both rain gauge and Multi-sensor Precipitation Estimator (MPE) rainfall inputs. Differences in simulation results were compared in terms of the hydrographs at different locations in the basin as well as the spatial distribution of hydrologic processes. GSSHA simulations driven by MPE rainfall match very well the USGS observed hydrograph. GSSHA simulation driven by rain gauge rainfall for June-2002 storm event underestimated the peak flow.

  13. Identification of Radar Facies and Linked Process-Based Palaeo-environmental Interpretations, Cooloola Sand Mass, Queensland, Australia

    Science.gov (United States)

    Gontz, A. M.; McCallum, A. B.; Moss, P. T.; Shulmeister, J.

    2015-12-01

    During 2015 and 2014, nearly 60 km of high-resolution ground penetrating radar data were acquired on the Cooloola Sand Mass (CSM) in southeastern coastal Queensland. The CSM is part of the world's largest downdrift sand system. It contains three of the world's largest sand islands, several National Parks, a UNESCO World Heritage Site and covers 500 km of the eastern Australian coastline in northern New South Wales and southern Queensland. The large (>200 m) composite dunes of the CSM exhibit multiple activation phases, coastally eroding bluffs and dune development is not obvious from surficial exposures. This provides an ideal environment for ground penetrating radar. The dune sequences have been provisionally dated to the mid Quaternary through present and represent the potential for a large palaeo-environmental proxy dataset. GPR imagery was collected using a MALA GeoSciences Ground Explorer (GX) system with 160 and 450 MHz antennae from the numerous physiographic and ecological provinces as well as mapped surficial soil units at the CSM. These data were used to determine the subsurface architecture, identify radar facies and develop environmental interpretations. In the clean, aeolian quartz-rich sands, radar wave penetration exceeded 30 m (radar velocity = 0.07 m/ns) with the 160 MHz antenna. From the interpreted environmental units including palaeosol, dune slip face, dune stoss face, sand blow, beach, estuarine and fluvial, we are developing maps to relate the units and focus a detailed sampling regime that includes OSL, sediment geochemistry and sedimentology, The interpreted units, stratigraphic correlation and spatial distribution of the facies is the first step in a broader project to unravel the Quaternary environmental and climate records that are archived within the sediments of the CSM.

  14. Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band

    International Nuclear Information System (INIS)

    In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2–12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance

  15. Weather Radar Impact Zones

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent an inventory of the national impacts of wind turbine interference with NEXRAD radar stations. This inventory was developed by the NOAA Radar...

  16. Demonstration of radar reflector detection and ground clutter suppression using airborne weather and mapping radar

    Science.gov (United States)

    Anderson, D. J.; Bull, J. S.; Chisholm, J. P.

    1982-01-01

    A navigation system which utilizes minimum ground-based equipment is especially advantageous to helicopters, which can make off-airport landings. Research has been conducted in the use of weather and mapping radar to detect large radar reflectors overland for navigation purposes. As initial studies have not been successful, investigations were conducted regarding a new concept for the detection of ground-based radar reflectors and eliminating ground clutter, using a device called an echo processor (EP). A description is presented of the problems associated with detecting radar reflectors overland, taking into account the EP concept and the results of ground- and flight-test investigations. The echo processor concept was successfully demonstrated in detecting radar reflectors overland in a high-clutter environment. A radar reflector target size of 55 dBsm was found to be adequate for detection in an urban environment.

  17. Angular glint calculation and analysis of radar targets via adaptive cross approximation algorithm

    Institute of Scientific and Technical Information of China (English)

    Miao Sui; Xiaojian Xu

    2014-01-01

    Angular glint is a significant electromagnetic (EM) scat-tering signature of extended radar targets. Based on the adaptive cross approximation (ACA) algorithm accelerated method of mo-ments (MoM) and the plane incident wave assumption, the narrow-band, wideband and newly developed high-resolution range profile (HRRP) based angular glint calculation formulations are derived and applied to arbitrarily shaped three-dimensional (3D) perfectly electrical y conducting (PEC) objects. In addition, the near-field angular glint is emphasized, which is of great importance for radar-seeker applications. Furthermore, with the HRRP based angular glint, an approach to rigorously determine range resolution cel s which own relatively smal er angular glint is provided. Numerical results are presented with new findings to demonstrate the useful-ness of the developed formulations.

  18. Network radar countermeasure systems integrating radar and radar countermeasures

    CERN Document Server

    Jiang, Qiuxi

    2016-01-01

    This is the very first book to present the network radar countermeasure system. It explains in detail the systematic concept of combining radar and radar countermeasures from the perspective of the information acquisition of target location, the optimization of the reconnaissance and detection, the integrated attack of the signals and facilities, and technological and legal developments concerning the networked system. It achieves the integration of the initiative and passivity, detection and jamming. The book explains how the system locates targets, completes target identification, tracks targets and compiles the data.

  19. Digital LPI Radar Detector

    OpenAIRE

    Ong, Peng Ghee; Teng, Haw Kiad

    2001-01-01

    Approved for public release; distribution is unlimited The function of a Low Probability ofIntercept (LPI) radar is to prevent its interception by an Electronic Support (ES) receiver. This objective is generally achieved through the use of a radar waveform that is mismatched to those waveforms for which an ES receiver is tuned. This allows the radar to achieve a processing gain, with respect to the ES receiver, that is equal to the time-bandwidth product ofthe radar waveform. This...

  20. Secondary Surveillance Radar Antenna

    OpenAIRE

    Schejbal, Vladimír; Bezoušek, Pavel; Pidanič, Jan; Chyba, Milan

    2013-01-01

    This paper deals with a secondary surveillance radar (SSR) array antenna, which is intended for a system combining the secondary surveillance radar antenna and the primary surveillance radar antenna. It describes the patch array elements and the synthesis for the secondary surveillance radar array, considering both elevation and azimuth patterns for sum, difference, and sidelobe-suppression beams, and suspended stripline couplers. The utilization of multilayer techniques allows the connection...

  1. Software Radar Technology

    Directory of Open Access Journals (Sweden)

    Tang Jun

    2015-08-01

    Full Text Available In this paper, the definition and the key features of Software Radar, which is a new concept, are proposed and discussed. We consider the development of modern radar system technology to be divided into three stages: Digital Radar, Software radar and Intelligent Radar, and the second stage is just commencing now. A Software Radar system should be a combination of various modern digital modular components conformed to certain software and hardware standards. Moreover, a software radar system with an open system architecture supporting to decouple application software and low level hardware would be easy to adopt "user requirements-oriented" developing methodology instead of traditional "specific function-oriented" developing methodology. Compared with traditional Digital Radar, Software Radar system can be easily reconfigured and scaled up or down to adapt to the changes of requirements and technologies. A demonstration Software Radar signal processing system, RadarLab 2.0, which has been developed by Tsinghua University, is introduced in this paper and the suggestions for the future development of Software Radar in China are also given in the conclusion.

  2. Radar: Human Safety Net

    Science.gov (United States)

    Ritz, John M.

    2016-01-01

    Radar is a technology that can be used to detect distant objects not visible to the human eye. A predecessor of radar, called the telemobiloscope, was first used to detect ships in the fog in 1904 off the German coast. Many scientists have worked on the development and refinement of radar (Hertz with electromagnetic waves; Popov with determining…

  3. Radar Time and a State-Space Based Approach To Quantum Field Theory In Gravitational and Electromagnetic Backgrounds

    CERN Document Server

    Dolby, C E; Dolby, Carl E.; Gull, Stephen F.

    2002-01-01

    In a recent paper (hep-th/0103228) a new initial value formulation of fermionic QFT was presented that is applicable to an arbitrary observer in any electromagnetic background. This approach suggests a consistent particle interpretation at all times, with the concept of `radar time' used to generalise this interpretation to an arbitrarily moving observer. In the present paper we extend this formalism to allow for gravitational backgrounds. The observer-dependent particle interpretation generalises Gibbons' definition to non-stationary spacetimes. This allows any observer to be considered, providing a particle interpretation that depends {\\it only} on the observer's motion and the background, not on any choice of coordinates or gauge, or on details of their particle detector. Consistency with known results is demonstrated for the cases of Rindler space and deSitter space. Radar time is also considered for an arbitrarily moving observer in an arbitrary 1+1 dimensional spacetime, and for a comoving observer in a...

  4. The effect of radar-based QPE on the Fractions Skill Score used at the QPF verification

    Czech Academy of Sciences Publication Activity Database

    Zacharov, Petr, jr.; Řezáčová, Daniela

    2010-01-01

    Roč. 25, - (2010), s. 91-95. ISSN 1680-7340 R&D Projects: GA MŠk OC 112; GA AV ČR(CZ) IAA300420804; GA ČR GA205/07/0905 Institutional research plan: CEZ:AV0Z30420517 Keywords : quantitative precipitation forecast * quantitative precipitation estimate * radar * verification * convective weather Subject RIV: DG - Athmosphere Sciences, Meteorology www.adv-geosci.net/25/91/2010/

  5. Effect of rainfall variability on the hydrological behavior of urban basins : A simulation study based on weather radar data

    OpenAIRE

    MORENA, F; Andrieu, H.; RODRIGUEZ, F; CREUTIN, JD

    2002-01-01

    The objective herein is to study the influence of the spatial rainfall variability on the resulting variability of the unit hydrograph of urban basins. This simulation study concerns two basins of surface areas of 460 ha and 180 ha represented by a distributed rainfall-runoff model. The forcing of the model with radar rainfall measurements at a 250 m spatial resolution is studied and compared with the forcing of the model with spatially uniform rainfall rates. A theoretical formulation,...

  6. High-Resolution Raindrop Size Distribution Retrieval Based on the Doppler Spectrum in the Case of Slant Profiling Radar

    OpenAIRE

    Unal, C.M.H.

    2015-01-01

    Doppler spectra from vertically profiling radars are usually considered to retrieve the raindrop size distribution (DSD). However, to exploit both fall velocity spectrum and polarimetric measurements, Doppler spectra acquired in slant profiling mode should be explored. Rain DSD samples are obtained from simultaneously measured vertical and slant profile Doppler spectra and evaluated. In particular, the effect of the horizontal wind and the averaging time are investigated. The Doppler spectrum...

  7. Identification and removal of non-meteorological echoes in dual-polarization radar data based on a fuzzy logic algorithm

    Science.gov (United States)

    Ye, Bo-Young; Lee, GyuWon; Park, Hong-Mok

    2015-09-01

    A major issue in radar quantitative precipitation estimation is the contamination of radar echoes by non-meteorological targets such as ground clutter, chaff, clear air echoes etc. In this study, a fuzzy logic algorithm for the identification of non-meteorological echoes is developed using optimized membership functions and weights for the dual-polarization radar located at Mount Sobaek. For selected precipitation and non-meteorological events, the characteristics of the precipitation and non-meteorological echo are derived by the probability density functions of five fuzzy parameters as functions of reflectivity values. The membership functions and weights are then determined by these density functions. Finally, the nonmeteorological echoes are identified by combining the membership functions and weights. The performance is qualitatively evaluated by long-term rain accumulation. The detection accuracy of the fuzzy logic algorithm is calculated using the probability of detection (POD), false alarm rate (FAR), and clutter-signal ratio (CSR). In addition, the issues in using filtered dual-polarization data are alleviated.

  8. An integrated sea monitoring system based on a X-band wave radar to support the removal activities of the Costa Concordia wreck.

    Science.gov (United States)

    Gozzini, Bernardo; Serafino, Francesco; Lugni, Claudio; Antonini, Andrea; Costanza, Letizia; Orlandi, Andrea; Arturi, Daniele; Ludeno, Giovanni; Natale, Antonio; Soldovieri, Francesco; Ortolani, Alberto; Brandini, Carlo

    2013-04-01

    The planning and management of different types of operations at sea requires a number of sea state data as much in real-time as possible, for rapid and effective response to different situations. This need is particularly strong in emergency management practices, in accidents due to man-made or natural causes, that require the planning of civil protection activities (such as search-and-rescue, cleaning of pollution, ship recovery), transport planning etc. The use of X-band radar technology nowadays provides great advantages over traditional in-situ and satellite-based techniques for sea state measuring, to update information on waves and currents over a sea area with high spatial and temporal resolution. Other advantages include a good spatial coverage around the area of interest, the flexibility of use, the capacity to provide, on-demand and when necessary, complementary information (possible oil spills detection, integration with VTS, etc.). X-band coastal radars (so-called "wave-radars") are widely used in the monitoring of large marine areas, in integration with in-situ measurements, satellites and other radar types (HF), as a key element of the observational component of present operational oceanography systems. Outside of these systems, the use of this technology to support emergency management practices is very promising for both the quality and quantity of available parameters, and for an easy integration with all other available monitoring and forecasting tools. A case study particularly relevant is offered by the presence of the Costa Concordia ship near the Giglio Island. The management of this disaster has requested at an early stage a large number of data to support the monitoring of marine environment around the ship, e.g. to optimally plan water samples. In the next and present phase, to support the highly risky and costly activities linked to the wreck removal, which are extremely sea-state dependent, the installation of a wave-radar allows to

  9. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

    Directory of Open Access Journals (Sweden)

    Sukanta Das

    2014-01-01

    Full Text Available In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth.

  10. EM-based optimization of microwave circuits using artificial neural networks: the state of the art

    OpenAIRE

    Rayas-Sánchez, José E.

    2004-01-01

    This paper reviews the current state-of-the-art in electromagnetic (EM)-based design and optimization of microwave circuits using artificial neural networks (ANNs). Measurement-based design of microwave circuits using ANNs is also reviewed. The conventional microwave neural optimization approach is surveyed, along with typical enhancing techniques, such as segmentation, decomposition, hierarchy, design of experiments and clusterization. Innovative strategies for ANN-based design exploiting...

  11. Stepped-frequency radar sensors theory, analysis and design

    CERN Document Server

    Nguyen, Cam

    2016-01-01

    This book presents the theory, analysis and design of microwave stepped-frequency radar sensors. Stepped-frequency radar sensors are attractive for various sensing applications that require fine resolution. The book consists of five chapters. The first chapter describes the fundamentals of radar sensors including applications followed by a review of ultra-wideband pulsed, frequency-modulated continuous-wave (FMCW), and stepped-frequency radar sensors. The second chapter discusses a general analysis of radar sensors including wave propagation in media and scattering on targets, as well as the radar equation. The third chapter addresses the analysis of stepped-frequency radar sensors including their principles and design parameters. Chapter 4 presents the development of two stepped-frequency radar sensors at microwave and millimeter-wave frequencies based on microwave integrated circuits (MICs), microwave monolithic integrated circuits (MMICs) and printed-circuit antennas, and discusses their signal processing....

  12. Scanning ARM Cloud Radar Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  13. EM-based optimization exploiting partial space mapping and exact sensitivities

    DEFF Research Database (Denmark)

    Bandler, John W.; Mohamed, Achmed S.; Bakr, Mohamed H.;

    2002-01-01

    We present a family of robust techniques for exploiting sensitivities in electromagnetic (EM)-based circuit optimization through space mapping (SM) technology. We utilize derivative information for parameter extractions and mapping updates. We exploit a partial SM (PSM) concept, where a reduced set...... of parameters is sufficient for parameter extraction optimization. It reflects the idea of tuning and execution time is reduced. Upfront gradients of both EM (fine) model and coarse surrogates can initialize possible mapping approximations. We introduce several effective approaches for updating the mapping...

  14. Inatividade física em idosos não institucionalizados: estudo de base populacional

    OpenAIRE

    Bruno Morbeck de Queiroz; Raildo da Silva Coqueiro; João Souza Leal Neto; Adriano Ferreti Borgatto; Aline Rodrigues Barbosa; Marcos Henrique Fernandes

    2014-01-01

    O objetivo deste estudo é descrever a prevalência de inatividade física e analisar os fatores sociodemográficos, de estilo de vida e condições de saúde associados em idosos do Nordeste brasileiro. Estudo descritivo e de associação, baseado em dados secundários originados de uma pesquisa epidemiológica de base populacional envolvendo 316 idosos. O nível de atividade física foi avaliado por meio do International Physical Activity Questionnaire. As variáveis explanatórias foram: sexo, grupo etár...

  15. Agricultura orgânica em áreas urbanas e periurbanas com base na agroecologia.

    OpenAIRE

    Aquino, Adriana Maria de; Assis, Renato Linhares de

    2007-01-01

    A agricultura orgânica com base na agroecologia é o mote tecnológico adequado à realidade dos agroecossistemas urbanos. Este artigo ressalta a necessidade de se desenvolver tecnologias e insumos específicos. A partir de experiências com agricultura urbana em diferentes países em desenvolvimento, evidencia-se a necessidade de se buscar capacidades locais e apoio do poder público, especialmente nas iniciativas da sociedade organizada e mobilizada para a produção agrícola urbana.

  16. Impacto de baixa velocidade em estruturas sandwich à base de cortiça

    OpenAIRE

    Nunes, Cláudia Patrícia Zeferino

    2009-01-01

    Os componentes tipo sandwich têm alcançado uma vasta aceitação em aplicações estruturais, devido às suas vantagens relativamente a outros materiais em termos de melhoria de estabilidade, elevada rigidez e resistência específicas. Os compósitos à base de aglomerados de cortiça apresentam-se como uma das alternativas mais promissoras aos materiais sintéticos para a construção de estruturas sandwich. Além das suas características estruturais únicas que permitem, entre outros aspectos, uma melhor...

  17. Ground and Space Radar Volume Matching and Comparison Software

    Science.gov (United States)

    Morris, Kenneth; Schwaller, Mathew

    2010-01-01

    This software enables easy comparison of ground- and space-based radar observations. The software was initially designed to compare ground radar reflectivity from operational, ground based Sand C-band meteorological radars with comparable measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite s Precipitation Radar (PR) instrument. The software is also applicable to other ground-based and space-based radars. The ground and space radar volume matching and comparison software was developed in response to requirements defined by the Ground Validation System (GVS) of Goddard s Global Precipitation Mission (GPM) project. This software innovation is specifically concerned with simplifying the comparison of ground- and spacebased radar measurements for the purpose of GPM algorithm and data product validation. This software is unique in that it provides an operational environment to routinely create comparison products, and uses a direct geometric approach to derive common volumes of space- and ground-based radar data. In this approach, spatially coincident volumes are defined by the intersection of individual space-based Precipitation Radar rays with the each of the conical elevation sweeps of the ground radar. Thus, the resampled volume elements of the space and ground radar reflectivity can be directly compared to one another.

  18. Value-based <em>Q(s,S) em>policy for joint replenishments

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    replenishment order is issued, if the expected cost of ordering immediately according to the (s, S) policy is less than the expected cost of deferring the order until the next demand or until the level Q is reached. We use simulation to evaluate our policy. Applying the value-based Q(s, S) policy to a standard...

  19. Psicoterapia baseada em evidências em crianças e adolescentes Evidence-based psychotherapies for children and adolescents

    Directory of Open Access Journals (Sweden)

    Gabriel Ferreira Pheula

    2007-01-01

    Full Text Available CONTEXTO: O termo tratamentos baseados em evidências refere-se a intervenções que possuem evidência de eficácia em pesquisas empíricas. Tratamentos psicológicos baseados em evidências têm sido identificados como um objetivo principal nos Estados Unidos, e, atualmente, há uma clara orientação em direção à sua indicação para os transtornos psiquiátricos mais prevalentes. OBJETIVO: Revisar a efetividade de intervenções psicossociais para as principais formas clínicas dos transtornos mentais na infância e adolescência, e os desafios para a pesquisa em tratamentos baseados em evidência. MÉTODOS: Revisão bibliográfica do banco de dados Medline, de 1985 a 2005, e revisão de artigos encontrados em capítulos de livros e artigos de revisão. RESULTADOS: Psicoterapias com suporte empírico em depressão, ansiedade, transtornos do comportamento disruptivo e transtorno de déficit de atenção/hiperatividade. CONCLUSÃO: Houve um progresso importante na pesquisa em psicoterapia na infância e adolescência, que se reflete na quantidade de estudos e na identificação de tratamentos baseados em evidências. O desafio atual engloba a generalização de tais achados para a prática clínica.BACKGROUND: Evidence-based treatments refer to interventions that have empirical research on their behalf. Evidence-based psychological therapy have been identified as a national goal in United States, and there is now clear guidance regarding referral for major mental health conditions. OBJECTIVE: Review the effectiveness of psychosocial interventions for all major forms of mental health problems in childhood and adolescence, and the challenges to research Evidence-Based treatments. METHODS: Computerized search of Medline database from 1985 to 2005 and review bibliographies of book chapters and review articles. RESULTS: We present empirically based psychological treatments for depression, anxiety, disruptive behavior disorder, attention deficit

  20. Radar and optical leonids

    Directory of Open Access Journals (Sweden)

    N. Brosch

    2004-01-01

    Full Text Available We present joint optical-radar observations of meteors collected near the peak of the Leonid activity in 2002. We show four examples of joint detections with a large, phased array L-band radar and with intensified video cameras. The general characteristic of the radar-detected optical meteors is that they show the radar detection below the termination of the optical meteor. Therefore, at least some radar events associated with meteor activity are neither head echoes nor trail echoes, but probably indicate the formation of 'charged clouds' after the visual meteor is extinguished.

  1. Understanding radar systems

    CERN Document Server

    Kingsley, Simon

    1999-01-01

    What is radar? What systems are currently in use? How do they work? This book provides engineers and scientists with answers to these critical questions, focusing on actual radar systems in use today. It is a perfect resource for those just entering the field, or as a quick refresher for experienced practitioners. The book leads readers through the specialized language and calculations that comprise the complex world of radar engineering as seen in dozens of state-of-the-art radar systems. An easy to read, wide ranging guide to the world of modern radar systems.

  2. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Ng, L C; Holzrichter, J F; Larson, P E

    2001-10-25

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.

  3. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    International Nuclear Information System (INIS)

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation

  4. Nhs: Network-based Hierarchical Segmentation for Cryo-EM Density Maps

    Science.gov (United States)

    Burger, Virginia; Chennubhotla, Chakra

    2012-01-01

    Electron cryo-microscopy (cryo-EM) experiments yield low-resolution (3–30Å) 3D-density maps of macromolecules. These density maps are segmented to identify structurally distinct proteins, protein domains, and sub-units. Such partitioning aids the inference of protein motions and guides fitting of high-resolution atomistic structures. Cryo-EM density map segmentation has traditionally required tedious and subjective manual partitioning or semi-supervised computational methods, while validation of resulting segmentations has remained an open problem in this field. Our network-based bias-free segmentation method for cryo-EM density map segmentation, Nhs (Network-based hierarchical segmentation), provides the user with a multi-scale partitioning, reflecting local and global clustering, while requiring no user input. This approach models each map as a graph, where map voxels constitute nodes and edges connect neighboring voxels. Nhs initiates Markov diffusion (or random walk) on the weighted graph. As Markov probabilities homogenize through diffusion, an intrinsic segmentation emerges. We validate the segmentations with ground-truth maps based on atomistic models. When implemented on density maps in the 2010 Cryo-EM Modeling Challenge, Nhs efficiently and objectively partitions macromolecules into structurally and functionally relevant sub-regions at multiple scales. PMID:22696408

  5. Sintomatologia depressiva em adolescentes iniciais: estudo de base populacional Depressive symptomatology in early adolescents: population-based study

    OpenAIRE

    Luciano Dias de Mattos Souza; Rodrigo Sinnott Silva; Russélia Vanila Godoy; Ana Laura Sica Cruzeiro; Augusto Duarte Faria; Ricardo Tavares Pinheiro; Bernardo Lessa Horta; Ricardo Azevedo da Silva

    2008-01-01

    OBJETIVO: Verificar a prevalência de sintomatologia depressiva em adolescentes entre 11 e 15 anos em Pelotas, RS, e identificar seus fatores associados. MÉTODOS: Estudo transversal de base populacional com amostra representativa de adolescentes da zona urbana da cidade de Pelotas, RS. Dos 448 setores censitários existentes no município, 79 foram aleatoriamente sorteados. Os jovens entre 11 e 15 anos localizados nestes setores foram convidados a responder o questionário auto-aplicado que conti...

  6. Phylogeny of <em>Orchidantha> (Lowiaceae) and the Zingiberales Based on Six DNA Regions

    DEFF Research Database (Denmark)

    Johansen, Louise Buchholt

    2005-01-01

    Very little is known about the small, tropical, monogeneric monocotyledon family Lowiaceae within the order Zingiberales. The phylogenetic position of Lowiaceae within Zingiberales is unclear, as are relationships within its single genus Orchidantha, which includes at least 16 species. This paper...... indicates that Lowiaceae is sister to all the remaining families of Zingiberales. An analysis of the family (14 species) based on a data set consisting of six plastid and nuclear DNA regions, includes the first use of a cam intron for estimating phylogeny. The results suggest that the nuclear calmodulin...

  7. GPR para a verificação do nível d'água subterrânea em transição floresta amazônica e cerrado Ground Penetratin Radar (GPR water level monitoring study of a mature transitional tropical forest

    Directory of Open Access Journals (Sweden)

    Tânia Helena Marcelino

    2005-09-01

    Full Text Available Um estudo do monitoramento do nível de água foi realizado com medidas diretas e com Radar de Penetração no Solo (GPR em uma floresta tropical de transição para o cerrado. Três poços de monitoramento do nível de água foram instalados durante 2001/2002 em três locais diferentes: o primeiro em uma área de floresta permanente, outro em área de floresta manejada e outra em uma área de pasto. Os perfis de GPR mostram que o nível do topo do lençol freático aparece como um refletor horizontal forte em março e em agosto de 2002, e como um refletor fraco durante medidas em maio e outubro de 2001 com descontinuidades devido a diversas lentes de solo laterítico no solo. O topo do lençol de água é facilmente confundido com a presença de tais lentes. A umidade do solo teve uma influência nestes sinais da reflexão, mudando a constante dielétrica do solo. A profundidade do topo do lençol da água variou 1,8 m sob a floresta permanente, 0,9 m sob a floresta manejada e 3,7 m sob o pasto.A Ground Penetratin Radar (GPR water level monitoring study of a mature transitional tropical forest is presented. Three water tables monitoring wells were installed during 2001/2002 at three different sites: under permanent forest, under managed forest and pasture. The GPR profiles show that the water table appears as a strong horizontal reflector in March and August, 2002,and as a weak, discontinuous reflector during measurements in May and October 2001. Due to several laterite lenses in the soil, the water table can easily be mistaken in place of such lenses. Soil moisture had an influence on these reflection signals, changing the dielectric constant of soil. The depth of the water table varied 1.8 m under permanent forest, 0.9 m under management forest and 3.7 m under pasture.

  8. Study of signal recognition of radar emitter based on QPSO%基于QPSO的雷达辐射源信号识别方法研究

    Institute of Scientific and Technical Information of China (English)

    郭戈; 徐佳婧; 徐璟; 魏洁

    2014-01-01

    鉴于支持向量机(SVM)方法对雷达辐射源信号具有较理想的识别结果,但对模型参数没有具体选择方法的问题,设计了一种以具有量子行为的粒子群优化(QPSO)算法为参数优化方法的SVM分类器,并提出了基于QPSO-SVM的雷达辐射源信号识别方法.QPSO-SVM分类器在采用QPSO算法对SVM进行优化改进的同时,继承了SVM分类器泛化能力强的特点,对雷达辐射源信号识别问题具有良好的适应性.实验结果表明,与其他方法相比,本文方法在保证识别准确率的同时,降低了参数选择时间.%Considering that the SVM algorithm has an ideal recognition result for radar emitter signals, but no specific selection method for the model parameters, this paper designs an SVM classifier that uses QPSO algorithm as the optimization algorithm of parameters, and proposes a scheme of signal recognition of radar emitter based on QPSO-SVM. While the QPSO-SVM classifier optimizes and improves SVM using the QPSO algorithm, the proposed classifier keeps the strong generalization capability of SVM classifier, thus having the better adaptability for the signal recognition of radar emitter. Experimental results show that this proposed method can shorten the time for parameter selection while guaranteeing the accuracy rate of recognition, compared with other algorithms.

  9. Design on Radar Remote Monitoring System based on B/S Mode%B/S 模式雷达远程监控系统设计

    Institute of Scientific and Technical Information of China (English)

    张怀才; 姚振东

    2013-01-01

      X 波段小型天气雷达在防雹,人工增雨以及短时天气预报中起着重要作用,冰雹强度、位置信息以及雨量信息可以从雷达的回波图像中解析得到。针对雷达运行系统的网络化控制需求,这里以ASP.NET 为开发平台,结合 Windows Server2003自带的 Internet 信息服务器(IIS),使用 SVG 显示技术完成了基于 Web 的 B/S 模式的雷达远程实时监控系统的设计。实践结果表明,该雷达监控系统具有较好的交互性、扩展性和实时性。%Small X-band weather radar plays an important role in hail suppression, artificial precipitation and short-term weather forecast. The information of hail strength and location, including the information of rainfall can be read from the radar echo image. With ASP.NET as the development platform, the design of radar remote real-time monitoring system based on Web is completed in combination of SVG and IIS attached to Windows Server2003. This system could realize real-time monitoring and control through access to the web site on the Internet. Experiments indicate that this system is of good interactivity, scalability and real-time performance.

  10. A MoLC+MoM-based G0distribution parameter estimation method with application to synthetic aperture radar target detection

    Institute of Scientific and Technical Information of China (English)

    朱正为; 周建江; 郭玉英

    2015-01-01

    The accuracy of background clutter model is a key factor which determines the performance of a constant false alarm rate (CFAR) target detection method. G0 distribution is one of the optimal statistic models in the synthetic aperture radar (SAR) image background clutter modeling and can accurately model various complex background clutters in the SAR images. But the application of the distribution is greatly limited by its disadvantages that the parameter estimation is complex and the local detection threshold is difficult to be obtained. In order to solve the above-mentioned problems, an synthetic aperture radar CFAR target detection method using the logarithmic cumulant (MoLC) + method of moment (MoM)-based G0distribution clutter model is proposed. In the method, G0 distribution is used for modeling the background clutters, a new MoLC+MoM-based parameter estimation method coupled with a fast iterative algorithm is used for estimating the parameters of G0 distribution and an exquisite dichotomy method is used for obtaining the local detection threshold of CFAR detection, which greatly improves the computational efficiency, detection performance and environmental adaptability of CFAR detection. Experimental results show that the proposed SAR CFAR target detection method has good target detection performance in various complex background clutter environments.

  11. Prevalência de transtornos ansiosos e algumas comorbidades em idosos: um estudo de base populacional

    Directory of Open Access Journals (Sweden)

    Mayara B. Machado

    2016-03-01

    Full Text Available RESUMO Objetivo Avaliar a prevalência de transtornos ansiosos e fatores associados em uma amostra populacional de idosos do Sul de Santa Catarina. Métodos Estudo transversal com base em dados populacionais, que avaliou 1.021 indivíduos idosos entre 60 e 79 anos. Foram realizadas entrevistas domiciliares para aferição de variáveis sobre transtornos ansiosos, por meio do questionário MINI, dados sociodemográficos, hipertensão arterial sistêmica (HAS, infarto agudo do miocárdio (IAM e dosagem de colesterol. Resultados As prevalências entre os transtornos ansiosos foram de 22,0% para o transtorno de ansiedade generalizada (TAG; 14,8% para fobia social (FS; 10,5% para transtorno do pânico (TP; e 8,5% para o transtorno obsessivo-compulsivo (TOC. Além disso, 40,5% dos indivíduos apresentaram pelo menos um transtorno de ansiedade. A distribuição dos transtornos foi semelhante nos dois gêneros; TAG foi mais prevalente nos indivíduos de menor escolaridade; TOC foi mais presente em indivíduos casados ou em união estável. Em relação às variáveis clínicas, HAS foi associada à presença de TOC; FS foi associada com IAM; TOC e FS foram associados com HDL > 40 mg/dL. Conclusão Os dados demonstram que os quadros de ansiedade são muito frequentes em idosos da comunidade, se sobrepõem de forma significativa e estão associados a algumas variáveis clínicas cardiovasculares.

  12. Fiber optic coherent laser radar 3D vision system

    Energy Technology Data Exchange (ETDEWEB)

    Clark, R.B.; Gallman, P.G.; Slotwinski, A.R. [Coleman Research Corp., Springfield, VA (United States); Wagner, K.; Weaver, S.; Xu, Jieping [Colorado Univ., Boulder, CO (United States)

    1996-12-31

    This CLVS will provide a substantial advance in high speed computer vision performance to support robotic Environmental Management (EM) operations. This 3D system employs a compact fiber optic based scanner and operator at a 128 x 128 pixel frame at one frame per second with a range resolution of 1 mm over its 1.5 meter working range. Using acousto-optic deflectors, the scanner is completely randomly addressable. This can provide live 3D monitoring for situations where it is necessary to update once per second. This can be used for decontamination and decommissioning operations in which robotic systems are altering the scene such as in waste removal, surface scarafacing, or equipment disassembly and removal. The fiber- optic coherent laser radar based system is immune to variations in lighting, color, or surface shading, which have plagued the reliability of existing 3D vision systems, while providing substantially superior range resolution.

  13. Fiber optic coherent laser radar 3D vision system

    International Nuclear Information System (INIS)

    This CLVS will provide a substantial advance in high speed computer vision performance to support robotic Environmental Management (EM) operations. This 3D system employs a compact fiber optic based scanner and operator at a 128 x 128 pixel frame at one frame per second with a range resolution of 1 mm over its 1.5 meter working range. Using acousto-optic deflectors, the scanner is completely randomly addressable. This can provide live 3D monitoring for situations where it is necessary to update once per second. This can be used for decontamination and decommissioning operations in which robotic systems are altering the scene such as in waste removal, surface scarafacing, or equipment disassembly and removal. The fiber- optic coherent laser radar based system is immune to variations in lighting, color, or surface shading, which have plagued the reliability of existing 3D vision systems, while providing substantially superior range resolution

  14. On detection performance and system configuration of MIMO radar

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; WU Yong; PENG YingNing; WANG XiuTan

    2009-01-01

    Multiple-input multiple-output (MIMO) radar is a new concept with some new characteristics, such as multiple orthogonal waveforms and omnidirectional coverage. Based on Stein's lemma, we use relative entropy as a precise and general measure of error exponent to study detection performance for both MIMO radar and phased array radar. And based on derived analytical results, we further study the system configuration problem of Bistatic MIMO radar systems, where transmitters and receivers are located in different positions. Some interesting results are presented. For phased array radar, when the total numbers of transmitters and receivers are fixed, we should always make the number of transmitters equal to the number of receivers. For MIMO radar, we should use a small number of transmitters in low signal noise ratio (SNR) region, and make the number of transmitters equal to the number of receivers in high SNR region. These results are instructive for deployment of bistatic MIMO radar systems in the future.

  15. Radar-based dynamic testing of the cable-suspended bridge crossing the Ebro River at Amposta, Spain

    International Nuclear Information System (INIS)

    Microwave remote sensing is the most recent experimental methodology suitable to the non-contact measurement of deflections on large structures, in static or dynamic conditions. After a brief description of the radar measurement system, the paper addresses the application of microwave remote sensing to ambient vibration testing of a cable-suspended bridge. The investigated bridge crosses the Ebro River at Amposta, Spain and consists of two steel stiffening trusses and a series of equally spaced steel floor beams; the main span is supported by inclined stay cables and two series of 8 suspension cables. The dynamic tests were performed in operational conditions, with the sensor being placed in two different positions so that the response of both the steel deck and the arrays of suspension elements was measured. The experimental investigation confirms the simplicity of use of the radar and the accuracy of the results provided by the microwave remote sensing as well as the issues often met in the clear localization of measurement points

  16. Radar-based dynamic testing of the cable-suspended bridge crossing the Ebro River at Amposta, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, Carmelo [Politecnico di Milano, Dept. of Architecture, Built environment and Construction engineering (ABC), Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Luzi, Guido [Centre Tecnòlogic de Telecomunicacions de Catalunya (CTTC), Division of Geomatics, Av. Gauss, 7 E-08860 Castelldefels (Barcelona) (Spain)

    2014-05-27

    Microwave remote sensing is the most recent experimental methodology suitable to the non-contact measurement of deflections on large structures, in static or dynamic conditions. After a brief description of the radar measurement system, the paper addresses the application of microwave remote sensing to ambient vibration testing of a cable-suspended bridge. The investigated bridge crosses the Ebro River at Amposta, Spain and consists of two steel stiffening trusses and a series of equally spaced steel floor beams; the main span is supported by inclined stay cables and two series of 8 suspension cables. The dynamic tests were performed in operational conditions, with the sensor being placed in two different positions so that the response of both the steel deck and the arrays of suspension elements was measured. The experimental investigation confirms the simplicity of use of the radar and the accuracy of the results provided by the microwave remote sensing as well as the issues often met in the clear localization of measurement points.

  17. Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar

    Directory of Open Access Journals (Sweden)

    Shouguo Yang

    2015-12-01

    Full Text Available A novel spatio-temporal 2-dimensional (2-D processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters’ outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD and direction of arrival (DOA, and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results.

  18. A procedure to correct the effects of a relative delay between the quadrature components of radar signals at base band

    Directory of Open Access Journals (Sweden)

    Grydeland

    2005-01-01

    Full Text Available The real and imaginary parts of baseband signals are obtained from a real narrow-band signal by quadrature mixing, i.e. by mixing with cosine and sine signals at the narrow band's selected center frequency. We address the consequences of a delay between the outputs of the quadrature mixer, which arise when digital samples of the quadrature baseband signals are not synchronised, i.e. when the real and imaginary components have been shifted by one or more samples with respect to each other. Through analytical considerations and simulations of such an error on different synthetic signals, we show how this error can be expected to afflict different measurements. In addition, we show the effect of the error on actual incoherent scatter radar data obtained by two different digital receiver systems used in parallel at the EISCAT Svalbard Radar (ESR. The analytical considerations indicate a procedure to correct the error, albeit with some limitations due to a small singular region. We demonstrate the correction procedure on actually afflicted data and compare the results to simultaneously acquired unafflicted data. We also discuss the possible data analysis strategies, including some that avoid dealing directly with the singular region mentioned above.

  19. Laser radar in robotics

    Energy Technology Data Exchange (ETDEWEB)

    Carmer, D.C.; Peterson, L.M. [Environmental Research Inst. of Michigan, Ann Arbor, MI (United States)

    1996-02-01

    In this paper the authors describe the basic operating principles of laser radar sensors and the typical algorithms used to process laser radar imagery for robotic applications. The authors review 12 laser radar sensors to illustrate the variety of systems that have been applied to robotic applications wherein information extracted from the laser radar data is used to automatically control a mechanism or process. Next, they describe selected robotic applications in seven areas: autonomous vehicle navigation, walking machine foot placement, automated service vehicles, manufacturing and inspection, automotive, military, and agriculture. They conclude with a discussion of the status of laser radar technology and suggest trends seen in the application of laser radar sensors to robotics. Many new applications are expected as the maturity level progresses and system costs are reduced.

  20. Model-Based Estimation of Forest Canopy Height in Red and Austrian Pine Stands Using Shuttle Radar Topography Mission and Ancillary Data: a Proof-of-Concept Study

    Energy Technology Data Exchange (ETDEWEB)

    Brown Jr., C G; Sarabandi, K; Pierce, L E

    2007-04-06

    In this paper, accurate tree stand height retrieval is demonstrated using C-band Shuttle Radar Topography Mission (SRTM) height and ancillary data. The tree height retrieval algorithm is based on modeling uniform tree stands with a single layer of randomly oriented vegetation particles. For such scattering media, the scattering phase center height, as measured by SRTM, is a function of tree height, incidence angle, and the extinction coefficient of the medium. The extinction coefficient for uniform tree stands is calculated as a function of tree height and density using allometric equations and a fractal tree model. The accuracy of the proposed algorithm is demonstrated using SRTM and TOPSAR data for 15 red pine and Austrian pine stands (TOPSAR is an airborne interferometric synthetic aperture radar). The algorithm yields root-mean-square (rms) errors of 2.5-3.6 m, which is a substantial improvement over the 6.8-8.3-m rms errors from the raw SRTM minus National Elevation Dataset Heights.

  1. FMCW Radar Performance for Atmospheric Measurements

    Directory of Open Access Journals (Sweden)

    T. Ince

    2010-04-01

    Full Text Available Frequency-modulated continuous-wave radars (FMCW have been used in the investigation of the atmosphere since the late 1960’s. FMCW radars provide tremendous sensitivity and spatial resolution compared to their pulsed counterparts and are therefore attractive for clear-air remote-sensing applications. However, these systems have some disadvantages and performance limitations that have prevented their widespread use by the atmospheric science community. In this study, system performance of atmospheric FMCW radar is analyzed and some measurement limitations for atmospheric targets are discussed. The effects of Doppler velocities and spectral widths on radar performance, radar’s near-field operation, and parallax errors for two-antenna radar systems are considered. Experimental data collected by the highresolution atmospheric FMCW radar is used to illustrate typical performance qualitatively based on morphological backscattered power information. A post-processing based on single-lag covariance differences between the Bragg and Rayleigh echo is applied to estimate clear-air component from refractive index turbulence and perform quantitative analysis of FMCW radar reflectivity from atmospheric targets.

  2. Assimilating Doppler radar radial velocity and reflectivity observations in the weather research and forecasting model by a proper orthogonal-decomposition-based ensemble, three-dimensional variational assimilation method

    Science.gov (United States)

    Pan, Xiaoduo; Tian, Xiangjun; Li, Xin; Xie, Zhenghui; Shao, Aimei; Lu, Chunyan

    2012-09-01

    Doppler radar observations with high spatial and temporal resolution can effectively improve the description of small-scale structures in the initial condition and enhance the mesoscale and microscale model skills of numerical weather prediction (NWP). In this paper, Doppler radar radial velocity and reflectivity are simultaneously assimilated into a weather research and forecasting (WRF) model by a proper orthogonal-decomposition-based ensemble, three-dimensional variational assimilation method (referred to as PODEn3DVar), which therefore forms the PODEn3DVar-based radar assimilation system (referred to as WRF-PODEn3DVar). The main advantages of WRF-PODEn3DVar over the standard WRF-3DVar are that (1) the PODEn3DVar provides flow-dependent covariances through the evolving ensemble of short-range forecasts, and (2) the PODEn3DVar analysis can be obtained directly without an iterative process, which significantly simplifies the assimilation. Results from real data assimilation experiments with the WRF model show that WRF-PODEn3DVar simulation yields better rainfall forecasting than radar retrieval, and radar retrieval is better than the standard WRF-3DVar assimilation, probably because of the flow-dependence character embedded in the WRF-PODEn3DVar.

  3. Netted LPI radars

    OpenAIRE

    Menychtas, Charalampos.

    2011-01-01

    Approved for public release; distribution is unlimited. A significant number of Low Probability of Intercept (LPI) radars are used in various military applications, from guided weapons (such anti-ship missile), to large platforms (aircrafts, ships), to large systems (Integrated Air Defense Systems - IADS). The purpose of this thesis is to evaluate the performance of netted LPI radar systems. To do so, it commences with establishing the theoretical background for the LPI radar techniques an...

  4. Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems

    Directory of Open Access Journals (Sweden)

    Wen-Qin Wang

    2013-01-01

    Full Text Available It is well recognized that a wind turbine has a large radar cross-section (RCS and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results.

  5. Phased-array radar design application of radar fundamentals

    CERN Document Server

    Jeffrey, Thomas

    2009-01-01

    Phased-Array Radar Design is a text-reference designed for electrical engineering graduate students in colleges and universities as well as for corporate in-house training programs for radar design engineers, especially systems engineers and analysts who would like to gain hands-on, practical knowledge and skills in radar design fundamentals, advanced radar concepts, trade-offs for radar design and radar performance analysis.

  6. Guidelines for the integration of EMS based in ISO 14001 with Cleaner Production

    Directory of Open Access Journals (Sweden)

    José Augusto de Oliveira

    2016-06-01

    Full Text Available Abstract This study aims to propose guidelines for the integration of the Environmental Management System (EMS based on ISO 14001 with the Cleaner Production (CP. For this, a systematic review was applied and five case studies have been carried out in industrial companies with considerable environmental performance. Located in the state of São Paulo, the researched companies have got CP projects to ensure environmental and economic gains and shown prominent compatibilities with the EMS based on ISO 14001. The proposed guidelines were performed in three parts: the planning stage, the integration stage and the stage of evaluation and analysis. The main compatibilities include dissemination of the environmental culture, synergy between some specific requirements of the standard and the CP, as the general requirements, legal requirements, environmental policy, training, qualification and monitoring. The guidelines can increase operational efficiency and strategic environmental management in enterprises.

  7. SMAP Radar Processing and Calibration

    Science.gov (United States)

    West, R.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M.

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission is part of the NASA space-based Earth observation program, and consists of an L-band radar and radiometer scheduled for launch into sun synchronous orbit in late 2014. A joint effort of the Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC), the SMAP mission draws heavily on the design and risk reduction heritage of the Hydrosphere State (Hydros) mission [1], [2]. The SMAP science and applications objectives are to: 1) understand processes that link the terrestrial water, energy and carbon cycles, 2) estimate global water and energy fluxes at the land surface, 3) quantify net carbon flux in boreal landscapes, 4) enhance weather and climate forecast skill, and 5) develop improved flood prediction and drought monitoring capability. To meet these science objectives, SMAP ground processing will combine the attributes of the radar and radiometer observations (in terms of their spatial resolution and sensitivity to soil moisture, surface roughness, and vegetation) to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB (1 sigma) at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This paper will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation.

  8. FMWC Radar for Breath Detection

    DEFF Research Database (Denmark)

    Suhr, Lau Frejstrup; Tafur Monroy, Idelfonso; Vegas Olmos, Juan José

    We report on the experimental demonstration of an FMCW radar operating in the 25.7 - 26.6 GHz range with a repetition rate of 500 sweeps per second. The radar is able to track the breathing rate of an adult human from a distance of 1 meter. The experiments have utilized a 50 second recording window...... to accurately track the breathing rate. The radar utilizes a saw tooth modulation format and a low latency receiver. A breath tracking radar is useful both in medical scenarios, diagnosing disorders such as sleep apnea, and for home use where the user can monitor its health. Breathing is a central part of every...... sensing as other systems rely on either measuring the airflow at the mouth and nose through a mask or with a stretchable wire around the chest. In this paper a wireless system that is able to measure the breath rate of a human from a distance is presented. The system is based on a commercially available...

  9. Airport Surveillance Radar : Model 11

    Data.gov (United States)

    Department of Transportation — The Airport Surveillance Radar Model 11 (ASR-11) is a short-range digital, integrated primary and secondary surveillance radar (SSR) radar system with a 60 nautical...

  10. Polarisation basis transformation of weather radar measurements in the power domain

    OpenAIRE

    Otto, T.; Lu, J; Chandra, M.

    2009-01-01

    Polarisation diversity in radar remote sensing proved to be very successful in a variety of applications. Hydrometeors as raindrops or ice crystals are anisotropic radar targets giving rise to the use of polarisation diversity in weather radars. One advanced polarimetric weather radar is DLR's POLDIRAD in Oberpfaffenhofen. The huge data archive of this radar consists mainly of power measurements at diverse polarisation bases.

    This study investigates the possibility t...

  11. Prevalência de Diabetes Mellitus em Pelotas, RS: um estudo de base populacional Prevalence of Diabetes Mellitus in Southern Brazil: a population-based study

    OpenAIRE

    Juvenal Soares Dias da Costa; Maria Teresa Anselmo Olinto; Maria Cecília Formoso Assunção; Denise Petrucci Gigante; Silvia Macedo; Ana Maria Baptista Menezes

    2006-01-01

    OBJETIVO: Comparar a prevalência de Diabetes Mellitus em população adulta, residente em área urbana, segundo auto-referência e valores de exame de glicemia de jejum. MÉTODOS: Realizou-se um estudo transversal de base populacional, com 1.968 pessoas de 20 a 69 anos, residentes na zona urbana da cidade de Pelotas, Estado do Rio Grande do Sul, em 2000. Estimou-se uma amostra de 1.800 indivíduos. Realizaram-se visitas domiciliares em 40 setores censitários sorteados aleatoriamente. Foi aplicado u...

  12. Parametric Sparse Representation and Its Applications to Radar Sensing

    Directory of Open Access Journals (Sweden)

    Li Gang

    2016-02-01

    Full Text Available Sparse signal processing has been utilized to the area of radar sensing. Due to the presence of unknown factors such as the motion of the targets of interest and the error of the radar trajectory, a predesigned dictionary cannot provide the optimally spare representation of the actual radar signals. This paper will introduce a method called parametric sparse representation, which is a special case of dictionary learning and can dynamically learn the unknown factors during the radar sensing and achieve the optimally sparse representation of radar signals. This paper will also introduce the applications of parametric sparse representation to Inverse Synthetic Aperture Radar imaging (ISAR imaging, Synthetic Aperture Radar imaging (SAR autofocusing and target recognition based on micro-Doppler effect.

  13. A MU radar-based study of mid-latitude F region response to a geomagnetic disturbance

    International Nuclear Information System (INIS)

    During the night of January 20-21, 1989, ionospheric incoherent scatter power measurements were made with the MU (middle and upper atmosphere) radar at Shigaraki (geographic latitude 34.85 N, longitude 136.10 E; geomagnetic latitude 24.9 degree, longitude 204.3 degree). Japan, and the electron density profiles in the 180- to 1,000-km height range were derived at 8-min intervals. The observations showed the presence of three F region disturbances during the night. During the very large first disturbance, which lasted from 2,300 to 0240 LT approximately, the height of maximum electron density Nm increased by 220 km in 2 hours to reach an altitude of 600 km. The other two, smaller disturbances occurred during 0300-0500 LT and 0530-0700 LT approximately. A detailed interpretation of the above F region disturbances is given. Examination of some high- and middle-latitude magnetograms showed the beginning of an intense geomagnetic substorm at auroral latitudes at the start of the first F region disturbance, and a less intense substorm around the starting time of the second F region disturbance. On the basis of this evidence, the first two F region disturbances are interpreted as the result of large vertical drifts of F region ionization due to the substorm-generated east-west electric fields appearing at mid-latitudes. The patterns of h'F variations during this night at five ionospheric stations in Japan support the above interpretation. Additionally, during the second disturbance the possible presence of a wind perturbation due to the equatorward propagation of a wave disturbance, generated probably by the first major substorm, is indicated by the MU radar data and the ionosonde data. The third F region disturbance is attributed to a neutral wind perturbation associated with a gravity wave traveling equatorward, the wave being generated most plausibly by the Joule heating during the first major substorm

  14. Qualidade de experiência em sistemas de base de dados

    OpenAIRE

    Costa, Rogério Luís de Carvalho

    2010-01-01

    Este trabalho visa fornecer mecanismos para aumentar a satisfação dos utilizadores quando utilizam sistemas de bases de dados. Consideramos satisfação dos usuários em termos de Qualidade de Experiência (QoE). Desta forma, as nossas propostas visam aumentar o nível de QoE fornecido por sistemas de bases de dados. Sistemas de bases de dados tradicionais executam as operações imediatamente após a submissão e, como eles não permitem que os utilizadores expressem restrições relacionadas com ...

  15. A Memory-Based Approach to Two-Player Texas Hold'em

    Science.gov (United States)

    Rubin, Jonathan; Watson, Ian

    A Case-Based Reasoning system, nicknamed SARTRE, that uses a memory-based approach to play two-player, limit Texas Hold'em is introduced. SARTRE records hand histories from strong players and attempts to re-use this information to handle novel situations. SARTRE'S case features and their representations are described, followed by the results obtained when challenging a world-class computerised opponent. Our experimental methodology attempts to address how well SARTRE'S performance can approximate the performance of the expert player, who SARTRE originally derived the experience-base from.

  16. Performance characteristics of wind profiling radars

    Science.gov (United States)

    Strauch, R. G.; Frisch, A. S.; Weber, B. L.

    1986-01-01

    Doppler radars used to measure winds in the troposphere and lower stratosphere for weather analysis and forecasting are lower-sensitivity versions of mesosphere-stratosphere-troposphere radars widely used for research. The term wind profiler is used to denote these radars because measurements of vertical profiles of horizontal and vertical wind are their primary function. It is clear that wind profilers will be in widespread use within five years: procurement of a network of 30 wind profilers is underway. The Wave Propagation Laboratory (WPL) has operated a small research network of radar wind profilers in Colorado for about two and one-half years. The transmitted power and antenna aperture for these radars is given. Data archiving procedures have been in place for about one year, and this data base is used to evaluate the performance of the radars. One of the prime concerns of potential wind profilers users is how often and how long wind measurements are lacking at a given height. Since these outages constitute an important part of the performance of the wind profilers, they are calculated at three radar frequencies, 50-, 405-, and 915-MHz, (wavelengths of 6-, 0.74-, and 0.33-m) at monthly intervals to determine both the number of outages at each frequency and annual variations in outages.

  17. Ego-motion based on EM for bionic navigation

    Science.gov (United States)

    Yue, Xiaofeng; Wang, L. J.; Liu, J. G.

    2015-12-01

    Researches have proved that flying insects such as bees can achieve efficient and robust flight control, and biologists have explored some biomimetic principles regarding how they control flight. Based on those basic studies and principles acquired from the flying insects, this paper proposes a different solution of recovering ego-motion for low level navigation. Firstly, a new type of entropy flow is provided to calculate the motion parameters. Secondly, EKF, which has been used for navigation for some years to correct accumulated error, and estimation-Maximization, which is always used to estimate parameters, are put together to determine the ego-motion estimation of aerial vehicles. Numerical simulation on MATLAB has proved that this navigation system provides more accurate position and smaller mean absolute error than pure optical flow navigation. This paper has done pioneering work in bionic mechanism to space navigation.

  18. Dynamic gauge adjustment of high-resolution X-band radar data for convective rain storms: Model-based evaluation against measured combined sewer overflow

    DEFF Research Database (Denmark)

    Borup, Morten; Grum, Morten; Linde, Jens Jørgen;

    2016-01-01

    Numerous studies have shown that radar rainfall estimates need to be adjusted against rain gauge measurements in order to be useful for hydrological modelling. In the current study we investigate if adjustment can improve radar rainfall estimates to the point where they can be used for modelling......, well defined, 64 ha urban catchment, for nine overflow generating rain events. The dynamically adjusted radar data perform best when the aggregation period is as small as 10–20 min, in which case it performs much better than static adjusted radar data and data from rain gauges situated 2–3 km away....

  19. Determination of radar MTF

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  20. Java Radar Analysis Tool

    Science.gov (United States)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  1. Decoders for MST radars

    Science.gov (United States)

    Woodman, R. F.

    1983-01-01

    Decoding techniques and equipment used by MST radars are described and some recommendations for new systems are presented. Decoding can be done either by software in special-purpose (array processors, etc.) or general-purpose computers or in specially designed digital decoders. Both software and hardware decoders are discussed and the special case of decoding for bistatic radars is examined.

  2. Weather Radar Signals with Alpha Stable Distributions

    OpenAIRE

    Lagha, Mohand; Bensebti, Messaoud

    2007-01-01

    This work, treats about a modeling of the weather precipitation echoes detected by a weather pulse Doppler radar. The methods used for the simulation of the Doppler spectrum, and I & Q signals representing the precipitations radar echoes, is based on a macroscopic models, i.e. random processes with assigned spectra. We propose global model, with a power spectrum having a range of statistical distributions ranging between Cauchy and Gauss called alpha-stable model. The results obtained shows t...

  3. Micropower impulse radar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  4. Spaceborne weather radar

    Science.gov (United States)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  5. Principles of modern radar radar applications

    CERN Document Server

    Scheer, James A

    2013-01-01

    Principles of Modern Radar: Radar Applications is the third of the three-volume seriesof what was originally designed to be accomplished in one volume. As the final volumeof the set, it finishes the original vision of a complete yet bounded reference for radartechnology. This volume describes fifteen different system applications or class ofapplications in more detail than can be found in Volumes I or II.As different as the applications described, there is a difference in how these topicsare treated by the authors. Whereas in Volumes I and II there is strict adherence tochapter format and leve

  6. Material integrity verification radar

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) has the need for verification of 'as-built' spent fuel-dry storage containers and other concrete structures. The IAEA has tasked the Special Technologies Laboratory (STL) to fabricate, test, and deploy a stepped-frequency Material Integrity Verification Radar (MIVR) system to nondestructively verify the internal construction of these containers. The MIVR system is based on previously deployed high-frequency, ground penetrating radar (GPR) systems that have been developed by STL for the U.S. Department of Energy (DOE). Whereas GPR technology utilizes microwave radio frequency energy to create subsurface images, MTVR is a variation for which the medium is concrete instead of soil. The purpose is to nondestructively verify the placement of concrete-reinforcing materials, pipes, inner liners, and other attributes of the internal construction. The MIVR system underwent an initial field test on CANDU reactor spent fuel storage canisters at Atomic Energy of Canada Limited (AECL), Chalk River Laboratories, Ontario, Canada, in October 1995. A second field test at the Embalse Nuclear Power Plant in Embalse, Argentina, was completed in May 1996. The DOE GPR also was demonstrated at the site. Data collection and analysis were performed for the Argentine National Board of Nuclear Regulation (ENREN). IAEA and the Brazilian-Argentine Agency for the Control and Accounting of Nuclear Material (ABACC) personnel were present as observers during the test. Reinforcing materials were evident in the color, two-dimensional images produced by the MIVR system. A continuous pattern of reinforcing bars was evident and accurate estimates on the spacing, depth, and size were made. The potential uses for safeguard applications were jointly discussed. The MIVR system, as successfully demonstrated in the two field tests, can be used as a design verification tool for IAEA safeguards. A deployment of MIVR for Design Information Questionnaire (DIQ

  7. Lunar Radar Cross Section at Low Frequency

    Science.gov (United States)

    Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V.

    2002-01-01

    Recent bistatic measurements of the lunar radar cross-section have extended the spectrum to long radio wavelength. We have utilized the HF Active Auroral Research Program (HAARP) radar facility near Gakona, Alaska to transmit high power pulses at 8.075 MHz to the Moon; the echo pulses were received onboard the NASA/WIND spacecraft by the WAVES HF receiver. This lunar radar experiment follows our previous use of earth-based HF radar with satellites to conduct space experiments. The spacecraft was approaching the Moon for a scheduled orbit perturbation when our experiment of 13 September 2001 was conducted. During the two-hour experiment, the radial distance of the satellite from the Moon varied from 28 to 24 Rm, where Rm is in lunar radii.

  8. SuperDARN scalar radar equations

    CERN Document Server

    Berngardt, O I; Potekhin, A P

    2016-01-01

    The quadratic scalar radar equations are obtained for SuperDARN radars that are suitable for the analysis and interpretation of experimental data. The paper is based on a unified approach to the obtaining radar equations for the monostatic and bistatic sounding with use of hamiltonian optics and ray representation of scalar Green's function and without taking into account the polarization effects. The radar equation obtained is the sum of several terms corresponding to the propagation and scattering over the different kinds of trajectories, depending on their smoothness and the possibility of reflection from the ionosphere. It is shown that the monostatic sounding in the media with significant refraction, unlike the case of refraction-free media, should be analyzed as a combination of monostatic and bistatic scattering. This leads to strong dependence of scattering amplitude on background ionospheric density due to focusing mechanism and appearance of new (bistatic) areas of effective scattering with signific...

  9. On paleodrainage evolution in mid-late Epipleistocene based on radar remote sensing in northeastern Ejin Banner, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    WANGXinyuan; GUOHuadong; CHANGYueming; ZHALiangsong

    2004-01-01

    Radar remote sensing can acquire information of sub-surface covered by sand in arid area,detect surface roughness and vegetation coronet's layer and linear feature such as linear structure and channel sensitively. With sediment facies analysis, this paper studies the features of environmental evolution in mid-late Epipleistocene (60 ka BP-20 ka BP) in northeastem Ejin Banner. The conclusions are listed as follows: (1) The evolution of the three lakes, i.e. Gaxunnur, Sugunur and Tian'e lakes, are dominated by faults and regional climate. (2) By analyzing sedimentary section of old Juyanze Lake,the three lakes used to be a large outflow lake before 50 ka BP in northeastem Ejin Banner, and at 50 ka BP, temperature declined rapidly in northwestem China. The event caused the lake's shrinkage. (3)By fault activity uplift in the northem part of old Juyan Lake and depression in the southem part, the lake's water followed fi'om north to south at around 35 ka BP, old Juyanze fluvial fan was formed. At the same time, Juyan lake separated fi'om Sugunur Lake and Wentugunr old channel was abandoned.(4) In recent 2000 years, Ruoshui River is a wandering river, sometimes it flows into Juyan lake and sometimes Sugunur and Gaxunnur lakes. Due to human activities and over exploitation, the oasis ecosystem is rapidly degenerated in 15 years (1986-2000).

  10. Waterline Detection and Monitoring in the German Wadden Sea Using High Resolution Satellite-Based Radar Measurements

    Science.gov (United States)

    Wiehle, S.; Lehner, S.; Pleskachevsky, A.

    2015-04-01

    High resolution TerraSAR-X/TanDEM-X as well as Sentinel-1 remote sensing Synthetic Aperture Radar (SAR) data are used to determine and monitor the waterline in the Wadden Sea. In this very unique and dynamic coastal region in the southeastern North Sea, tidal flats extend several kilometers away from the coast during low tide with features like tidal inlets and sand banks. Under the influence of tidal water currents transporting large amounts of eroded material, inlets and sand banks move over time; heavy storms can even cause large variations in their extensions in merely a few hours. Observation of these obstacles is crucial for maritime security as high ship traffic is caused by the ports of Hamburg, Bremerhaven, Wilhelmshaven and others. Conventional monitoring campaigns with ships or airplanes are economically expensive and can only provide limited coverage. We present an automatic algorithm with Near Real-Time capability for extracting the waterline at the time of recording from SAR images, which allows for a fast and large scale determination of changes in coastal outlines. The comparison of recent acquisitions of TerraSAR-X and Sentinel-1 to bathymetry data of the Elbe estuary obtained in 2010 reveals significant changes in tidal flat structures.

  11. Alpine radar conversion for LAWR

    Science.gov (United States)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  12. Ground-penetrating radar methods

    Science.gov (United States)

    Ground-penetrating radar geophysical methods are finding greater and greater use in agriculture. With the ground-penetrating radar (GPR) method, an electromagnetic radio energy (radar) pulse is directed into the subsurface, followed by measurement of the elapsed time taken by the radar signal as it ...

  13. Radar and electronic navigation

    CERN Document Server

    Sonnenberg, G J

    2013-01-01

    Radar and Electronic Navigation, Sixth Edition discusses radar in marine navigation, underwater navigational aids, direction finding, the Decca navigator system, and the Omega system. The book also describes the Loran system for position fixing, the navy navigation satellite system, and the global positioning system (GPS). It reviews the principles, operation, presentations, specifications, and uses of radar. It also describes GPS, a real time position-fixing system in three dimensions (longitude, latitude, altitude), plus velocity information with Universal Time Coordinated (UTC). It is accur

  14. Polarimetric Doppler Weather Radar

    Science.gov (United States)

    Bringi, V. N.; Chandrasekar, V.

    2001-10-01

    This work provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The authors first discuss underlying topics such as electromagnetic scattering, polarization, and wave propagation. They then detail the engineering aspects of pulsed Doppler polarimetric radar, before examining key applications in meteorology and remote sensing. The book is aimed at graduate students of electrical engineering and atmospheric science as well as practitioners involved in the applications of polarimetric radar.

  15. Close-range radar rainfall estimation and error analysis

    OpenAIRE

    Beek, Remco; Leijnse, Hidde; Hazenberg, Pieter; Uijlenhoet, Remko

    2016-01-01

    Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are 1) radar calibration, 2) ground clutter, 3) wet radome attenuation, 4) rain induced attenuation, 5) vertical profile of reflectivity, 6) non-uniform beam filling, and 7) variations in rain drop size distribution (DSD). This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1–2 k...

  16. An Orthogonal Waveform Scheme for Imaging MIMO-Radar Applications

    OpenAIRE

    Rommel, Tobias; Patyuchenko, Anton; Laskowski, Piotr; Younis, Marwan; Krieger, Gerhard

    2013-01-01

    Synthetic Aperture Radar (SAR) based on Digital Beamforming (DBF) belongs to the family of Multi-Modal Radar Systems (MMRSs) which offer higher operational flexibility and improved performance compared to conventional radar systems using analog beam steering. DBF SAR, in particular, overcomes the fundamental resolution-coverage limitation of classical SAR systems and can deliver high resolution and simultaneously wide swath images. The purpose of this paper is to present recently obtained mea...

  17. Influences of weather phenomena on automotive laser radar systems

    OpenAIRE

    R. H. Rasshofer; Spies, M.; H. Spies

    2011-01-01

    Laser radar (lidar) sensors provide outstanding angular resolution along with highly accurate range measurements and thus they were proposed as a part of a high performance perception system for advanced driver assistant functions. Based on optical signal transmission and reception, laser radar systems are influenced by weather phenomena. This work provides an overview on the different physical principles responsible for laser radar signal disturbance and theoretical investi...

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

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

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

  19. Detection of Weather Radar Clutter

    OpenAIRE

    Bøvith, Thomas; Nielsen, Allan Aasbjerg; Hansen, Lars Kai

    2008-01-01

    Weather radars provide valuable information on precipitation in the atmosphere but due to the way radars work, not only precipitation is observed by the weather radar. Weather radar clutter, echoes from non-precipitating targets, occur frequently in the data, resulting in lowered data quality. Especially in the application of weather radar data in quantitative precipitation estimation and forecasting a high data quality is important. Clutter detection is one of the key components in achieving...

  20. Space mapping interpolating surrogates for highly optimized EM-based design of microwave devices

    DEFF Research Database (Denmark)

    Bandler, John; Cheng, Qingsha; Dakroury, Sameh; Hailu, Daniel; Madsen, Kaj; Mohamed, Ahmed; Pedersen, Frank

    A powerful optimization algorithm that incorporates Space Mapping (SM) and the new Output Space Mapping (OSM) to yield highly optimized results in a handful of fine model evaluations is presented. The new method employs an SM-based interpolating surrogate (SMIS) framework that aims at matching the...... surrogate with the fine model locally. Accuracy and convergence properties are demonstrated using a seven-section capacitively-loaded impedance transformer. A highly optimized six-section H-plane waveguide filter design emerges after only four HFSS EM simulations, excluding necessary Jacobian estimations...

  1. Radar Location Equipment Development Program: Phase I

    International Nuclear Information System (INIS)

    The work described in this report represents the first phase of a planned three-phase project designed to develop a radar system for monitoring waste canisters stored in a thick layer of bedded salt at the Waste Isolation Pilot Plant near Carlsbad, New Mexico. The canisters will be contained in holes drilled into the floor of the underground waste storage facility. It is hoped that these measurements can be made to accuracies of +-5 cm and +-20, respectively. The initial phase of this project was primarily a feasibility study. Its principal objective was to evaluate the potential effectiveness of the radar method in the planned canister monitoring application. Its scope included an investigation of the characteristics of radar signals backscattered from waste canisters, a test of preliminary data analysis methods, an assessment of the effects of salt and bentonite (a proposed backfill material) on the propagation of the radar signals, and a review of current ground-penetrating radar technology. A laboratory experiment was performed in which radar signals were backscattered from simulated waste canisters. The radar data were recorded by a digital data acquisition system and were subsequently analyzed by three different computer-based methods to extract estimates of canister location and tilt. Each of these methods yielded results that were accurate within a few centimeters in canister location and within 10 in canister tilt. Measurements were also made to determine the signal propagation velocities in salt and bentonite (actually a bentonite/sand mixture) and to estimate the signal attenuation rate in the bentonite. Finally, a product survey and a literature search were made to identify available ground-penetrating radar systems and alternative antenna designs that may be particularly suitable for this unique application. 10 refs., 21 figs., 4 tabs

  2. Wind Profiling Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Clutter present in radar return signals as used for wind profiling is substantially removed by carrying out a Daubechies wavelet transformation on a time series of...

  3. RADAR performance experiments

    Science.gov (United States)

    Leroux, C.; Bertin, F.; Mounir, H.

    1991-01-01

    Theoretical studies and experimental results obtained at Coulommiers airport showed the capability of Proust radar to detect wind shears, in clear air condition as well as in presence of clouds or rain. Several examples are presented: in a blocking highs situation an atmospheric wave system at the Brunt-Vaisala frequency can be clearly distinguished; in a situation of clouds without rain the limit between clear air and clouds can be easily seen; and a windshear associated with a gust front in rainy conditions is shown. A comparison of 30 cm clear air radar Proust and 5 cm weather Doppler radar Ronsard will allow to select the best candidate for wind shear detection, taking into account the low sensibility to ground clutter of Ronsard radar.

  4. Radar target detection simulation

    Directory of Open Access Journals (Sweden)

    Tarig Ibrahim Osman

    2014-12-01

    Full Text Available Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any knowledge and/or assumptions become in adequate due to the presence of multiple targets with varying signal return and usually non stationary background. Thus, any predetermined threshold may result in either increased false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not perform well in situations when the signal return from the target of interest is too low compared to the average level of the background .Track-before-detect techniques eliminate the need for a detection threshold and provide detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although trackbefore-detect techniques eliminate the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output of the filtering stage .This paper presents a computerized simulation model for target detection process. Moreover, the proposed model method is based on the target motion models, the output of the detection process can easily be employed for maneuvering target tracking.

  5. Ship-Borne Phased Array Radar Using GA Based Adaptive α-β-γ Filter for Beamforming Compensation and Air Target Tracking

    OpenAIRE

    J. Mar; Chen-Chih Liu; Basnet, M. B.

    2015-01-01

    Beam pointing error caused by ship motion over the ocean affects the tracking performance of the ship-borne phased array radar. Due to the dynamic nature of the sea environments, the ship-borne phased array radar must be able to compensate for the ship’s motion adaptively. In this paper, the adaptive α-β-γ filter is proposed for the ship-borne phased array radar to compensate for the beam pointing error and to track the air target. The genetic algorithm (GA) and the particle swarm optimizatio...

  6. Introduction to Development of Ground-Based Weather Radar in China%我国地基天气雷达技术系统发展介绍

    Institute of Scientific and Technical Information of China (English)

    许致火; 何建新; 史朝; 马建立

    2012-01-01

    With the development of radar technology across the world, the domestic radar has developed from conventional radar to single polarization Doppler, then double polarization Doppler, with the target information obtained being more abundant. The principles and product information of conventional radar, single polarization Doppler, and double polarization Doppler radar are introduced in detail. The performances of the next generation S-, C-, and X-band radar are compared, which has a certain reference value for the selection of the radar wavelength. The millimeter-wave Doppler radar is also introduced, which can obtain cloud structure information. The performance and trends of the next generation radar network are evaluated. The double polarization Doppler radar will be the main trend; the electronic-scanning small mobile radar will also become important for its flexibility, to make up the blind spots of next generation weather radar sounding.%回顾了我国天气雷达从常规雷达发展到单极化多普勒,再到双极化多普勒,雷达获取目标的参数信息更加丰富的过程.分析了常规、单极化多普勒、双极化多普勒雷达工作原理及其产品信息.对于我国新一代S、C和X波段的天气雷达性能进行了研究对比.阐述了毫米波段多普勒测云雷达工作原理及其产品.对新一代天气雷达网进行了分析及展望,双极化将是我国天气雷达网升级改造趋势,为弥补新一代天气雷达探测盲区,小型移动电扫描雷达也是一种辅助主雷达网可移动灵活布网的趋势.

  7. Uncertainty Model For Quantitative Precipitation Estimation Using Weather Radars

    Directory of Open Access Journals (Sweden)

    Ernesto Gómez Vargas

    2016-06-01

    Full Text Available This paper introduces an uncertainty model for the quantitatively estimate precipitation using weather radars. The model considers various key aspects associated to radar calibration, attenuation, and the tradeoff between accuracy and radar coverage. An S-band-radar case study is presented to illustrate particular fractional-uncertainty calculations obtained to adjust various typical radar-calibration elements such as antenna, transmitter, receiver, and some other general elements included in the radar equation. This paper is based in “Guide to the expression of Uncertainty in measurement” and the results show that the fractional uncertainty calculated by the model was 40 % for the reflectivity and 30% for the precipitation using the Marshall Palmer Z-R relationship.

  8. Ice crystal properties retrieval using radar spectral polarimetric measurements within ice/mixed-phase clouds

    NARCIS (Netherlands)

    Dufournet, Y.

    2010-01-01

    In the field of atmospheric research, ground-based radar systems are often employed to study ice/mixed-phase cloud properties based on retrieval techniques. These techniques convert the radar signal backscattered by each bulk of ice crystals being probed within the same radar resolution volume to cl

  9. 海上大气波导环境下舰载超视距雷达盲区研究%Preliminary Investigation on the Blind of Shipborne OTH Radar Based on Sea Atmospheric Duct

    Institute of Scientific and Technical Information of China (English)

    左雷; 涂拥军; 姚灿; 陈冰

    2011-01-01

    主要研究海上大气波导环境对舰载超视距雷达盲区的影响.首先对海洋蒸发波导和表面波导条件下雷达盲区的形成机理及其特性进行分析.在此基础上,对蒸发波导条件下雷达盲区在不同层结的变化进行深入研究,形成大气波导对舰载超视距雷达盲区影响的初步研究成果.最后对大气波导环境下超视距雷达盲区在军事上的应用进行展望,为后续雷达盲区特性的继续研究提供理论依据.%This paper was primarily aimed to investigate the influence on the Blind zone of Shipborne OTHR of sea atmospheric duct. Firstly, the produced mechanism and its characteristic of radar blind in the condition of atmospheric duct in evaporation or surface was analyzed respectively. Then, aimed at evaporation duct in evaporation, variety of radar blind in different atmospheric lay was deeply researched, and preliminary production of research on the OTH Radar blind based on Sea Atmospheric Duct was formed. Lastly, the application of the Blind of OTH radar based on Sea Atmospheric Duct in military affairs was prospected, in order to providing the theory basis in later radar blind research.

  10. Auxiliary signal processing system for a multiparameter radar

    Science.gov (United States)

    Chandrasekar, V.; Gray, G. R.; Caylor, I. J.

    1993-01-01

    The design of an auxiliary signal processor for a multiparameter radar is described with emphasis on low cost, quick development, and minimum disruption of radar operations. The processor is based around a low-cost digital signal processor card and personal computer controller. With the use of such a concept, an auxiliary processor was implemented for the NCAR CP-2 radar during a 1991 summer field campaign and allowed measurement of additional polarimetric parameters, namely, the differential phase and the copolar cross correlation. Sample data are presented from both the auxiliary and existing radar signal processors.

  11. The use of digital RF memories in radar signal processing

    Science.gov (United States)

    Clark, D. G. D.; Ingram, P. M.

    This paper describes the use that may be made of Digital RF Memories in developing and evaluating new radar systems. It outlines the basic DRFM technology showing how a DRFM works and the sort of performance that may be expected. The application of this technology to radar is then discussed showing the advantages that may be obtained through the use of coherent digital IF processing. Finally some experimental DRFM based radar configurations are described illustrating the results that have been achieved and the implications that these might have on future radar systems.

  12. Detecting and classifying low probability of intercept radar

    CERN Document Server

    Pace, Phillip E

    2003-01-01

    The drive is on to devise LPI radar systems that evade hostile detection as well as develop non-cooperative intercept devices that outsmart enemy LPI radar. Based on the author's own design experience, this comprehensive, hands-on book gives you the latest design and development techniques to innovate new LPI radar systems and discover new ways to intercept enemy LPI radar. and help you visually identify waveform parameters. Filled with more than 500 equations that provide rigorous mathematical detail, this book can be used by both entry-level and seasoned engineers. Besides thoroughly treatin

  13. Feasibility of mitigating the effects of windfarms on primary radar

    Energy Technology Data Exchange (ETDEWEB)

    Butler, M.M.; Johnson, D.A.

    2003-07-01

    The objectives of the study were to investigate the feasibility of modifying civil and military radars to mitigate the effects from wind turbines, to provide costings for implementing changes to the radar and to produce guidelines for planning wind farms in the vicinity of radars. The effect of wind turbines on radar signals, assessed through computer modelling, is summarised. The key aspects of turbine design that can be modified to minimise these effects are described. A key issue is the fact that no two radar installations are alike, with settings being customised for local requirements. As a consequence, a detailed understanding of the design and features of each individual radar would be required in order to assess the impact of a wind farm proposal. The costs of a programme of modifications to the civil ATC (air traffic control) radar base will depend on many factors. An estimate of costs is provided, based on the assumption that only 30 of the UK radars would need modification and that a range of modifications from very simple to very complex will be required. A number of other approaches, outside of modification of the radar system, may require investigation during a windfarm planning application, such as layout and location of the wind farm or changing air traffic routes in the vicinity of the wind farm.

  14. Detection and Classification of Finer-Grained Human Activities Based on Stepped-Frequency Continuous-Wave Through-Wall Radar.

    Science.gov (United States)

    Qi, Fugui; Liang, Fulai; Lv, Hao; Li, Chuantao; Chen, Fuming; Wang, Jianqi

    2016-01-01

    The through-wall detection and classification of human activities are critical for anti-terrorism, security, and disaster rescue operations. An effective through-wall detection and classification technology is proposed for finer-grained human activities such as piaffe, picking up an object, waving, jumping, standing with random micro-shakes, and breathing while sitting. A stepped-frequency continuous wave (SFCW) bio-radar sensor is first used to conduct through-wall detection of finer-grained human activities; Then, a comprehensive range accumulation time-frequency transform (CRATFR) based on inverse weight coefficients is proposed, which aims to strengthen the micro-Doppler features of finer activity signals. Finally, in combination with the effective eigenvalues extracted from the CRATFR spectrum, an optimal self-adaption support vector machine (OS-SVM) based on prior human position information is introduced to classify different finer-grained activities. At a fixed position (3 m) behind a wall, the classification accuracies of six activities performed by eight individuals were 98.78% and 93.23%, respectively, for the two scenarios defined in this paper. In the position-changing experiment, an average classification accuracy of 86.67% was obtained for five finer-grained activities (excluding breathing) of eight individuals within 6 m behind the wall for the most practical scenario, a significant improvement over the 79% accuracy of the current method. PMID:27314362

  15. Flood-threat zoning map of the urban area of Chocó (Quibdó. A study based on interpreting radar, satellite and aerial photograph images

    Directory of Open Access Journals (Sweden)

    Zamir Maturana Córdoba

    2010-04-01

    Full Text Available A zoning map of areas which flood due to the Atrato River and its tributaries (the Cabí, Caraño and Yesca over-flowing in the urban area of Chocó (Quibdo was drawn up to be used by aid authorities and Quibdó city as a planning and control tool. This research relied on CIAF (Centro Interamericano de Fotointerpretación support and assessment. This entity is a subsidiary institution of the Instituto Geográfico Agustín Codazzi which provided their installations and the required geographical material. This research was initially based on interpreting radar (INTERA, satellite (LANDSAT and aerial photographic images; this was verified by field verification of the in-terpreted data. Other variables such as climatic, geological, temperature, topographic conditions, historic and hydrological series and facts regarding the region were studied as additional information required for drawing conclusions. Aerial photographs provided the most reliable images due to their scales, quantity and quality and the date of when they were taken. Radar images (INTERA were also important when visually analysing a sector’s topography as they were produced by an active microwave sensor (totally eliminating climatic obstacles. On the contrary, satellite images did not have great relevance due to the amount of clouds hampering any kind of analysis. Complementing these results, a calibration curve for analysing this section’s maximum flow values was based on historical series data regarding the Atrato River’s flows and maximum levels recorded at the Quibdo hydrographical station and the river-bed’s cross-section. Implications that the river would overflow or has over-flowed were statistically estimated on these results, thereby setting the limits (supported by cartographic data for the corresponding areas at risk of flooding. A map marking areas at risk of flooding in the urban zone of Quibdó was then designed and a document prepared concluding that

  16. Methodology for tracking multi-target hidden in Doppler blind zone based on airborne and ground-based early warning radar cooperation%多普勒盲区条件下空地预警雷达多目标协同跟踪方法

    Institute of Scientific and Technical Information of China (English)

    付莹; 汤子跃; 孙永健

    2014-01-01

    针对多普勒盲区条件下预警机雷达多目标跟踪问题,基于交互式多模型(IMM,Interacting Multiple Models)、联合概率数据互联(JPDA,Joint Probability Data Association)和分布式不敏卡尔曼滤波(UKF,Unscented Kalman Filter)提出了预警机雷达与地基雷达对目标进行协同跟踪的方法。该方法利用目标的状态估计和预测实时计算每部雷达的动态融合权值,预测目标的多普勒频率。当预警机雷达对目标的量测不存在且检测到目标进入预警机雷达多普勒盲区时,由预警机雷达对目标状态进行外推,以此产生虚拟量测,用虚拟量测与地基雷达协同跟踪对目标的融合估计状态进行更新;若预警机雷达对目标的量测不存在且目标不是进入多普勒盲区时,由地基雷达单独对目标的融合估计状态进行更新。当目标飞出预警机雷达多普勒盲区后,将预警机雷达对目标的状态估计再次与地基雷达进行关联,并根据动态权值融合更新目标状态。仿真结果表明,该方法能够改善多普勒盲区内多目标航迹的连续性和跟踪精度。%Focusing on the tracking problem of multi-target hidden in AEW (airborne early warning) radar DBZ(Doppler blind zone), a collaborative tracking technique between AEW and ground-based radar was proposed based on IMM, distributed UKF and JPDA. The dynamic fusion weights were calculated for all radars and the Doppler frequency of each target was predicted in real time using target state estimation and prediction. On one hand, as long as the target measurements of AEW radar did not exist and the target was hidden in DBZ of AEW radar judged from its predicted Doppler frequency, targets state would be extrapolated by AEW radar, which creates virtual measurements. The target fusion state estimation would be updated by both virtual measurements of AEW radar and real measurements of ground-based radar. On the other hand, when the

  17. Emergency Medical Service (EMS) Stations

    Data.gov (United States)

    Kansas Data Access and Support Center — EMS Locations in Kansas The EMS stations dataset consists of any location where emergency medical services (EMS) personnel are stationed or based out of, or where...

  18. Prevalência de sobrepeso em adolescentes: um estudo de base populacional em uma cidade no Sul do Brasil

    Directory of Open Access Journals (Sweden)

    Dutra Carmem L.

    2006-01-01

    Full Text Available Avaliou-se a prevalência de sobrepeso em adolescentes e sua distribuição segundo varíaveis demográficas, sócio-econômicas, comportamentais e biológicas. Foram entrevistados 810 adolescentes entre 10 e 19 anos, residentes na zona urbana de Pelotas, Rio Grande do Sul, Brasil. O sobrepeso foi definido de acordo com a OMS (IMC > ou = Percentil 85, segundo idade e sexo conforme a população de referência do I National Health and Nutrition Examination Survey. O processo amostral foi por conglomerados e as análises bruta e ajustada (Regressão de Poisson levaram em conta o efeito de delineamento. A prevalência de sobrepeso em adolescentes foi de 19,3% (IC95%: 16,6-22,0 e não houve diferença entre os sexos. Adolescentes pertencentes aos níveis econômicos mais elevados, que realizaram dieta para emagrecer nos três meses anteriores à entrevista, que assistiam quatro horas ou mais de televisão por dia e que realizavam apenas uma ou duas refeições diárias apresentaram maior proporção de sobrepeso. Na análise ajustada, o sobrepeso nos meninos esteve diretamente associado com nível econômico e, nas meninas, com as variáveis dieta para emagrecer, número de horas diárias assistindo à televisão e inversamente associado com o número de refeições.

  19. Expression of Selected <em>Ginkgo em>>biloba em>Heat Shock Protein Genes After Cold Treatment Could Be Induced by Other Abiotic Stress

    Directory of Open Access Journals (Sweden)

    Feng Xu

    2012-05-01

    Full Text Available Heat shock proteins (HSPs play various stress-protective roles in plants. In this study, three <em>HSP> genes were isolated from a suppression subtractive hybridization (SSH cDNA library of <em>Ginkgo bilobaem> leaves treated with cold stress. Based on the molecular weight, the three genes were designated <em>GbHSP16.8em>, <em>GbHSP17em> and <em>GbHSP70em>. The full length of the three genes were predicted to encode three polypeptide chains containing 149 amino acids (Aa, 152 Aa, and 657 Aa, and their corresponding molecular weights were predicted as follows: 16.67 kDa, 17.39 kDa, and 71.81 kDa respectively. The three genes exhibited distinctive expression patterns in different organs or development stages. <em>GbHSP16.8em> and <em>GbHSP70em> showed high expression levels in leaves and a low level in gynoecia, <em>GbHSP17em> showed a higher transcription in stamens and lower level in fruit. This result indicates that <em>GbHSP16.8em> and <em>GbHSP70 em>may play important roles in <em>Ginkgo> leaf development and photosynthesis, and <em>GbHSP17em> may play a positive role in pollen maturation. All three <em>GbHSPs> were up-regulated under cold stress, whereas extreme heat stress only caused up-regulation of <em>GbHSP70em>, UV-B treatment resulted in up-regulation of <em>GbHSP16.8em> and <em>GbHSP17em>, wounding treatment resulted in up-regulation of <em>GbHSP16.8em> and <em>GbHSP70em>, and abscisic acid (ABA treatment caused up-regulation of <em>GbHSP70em> primarily.

  20. P-band radar ice sounding in Antarctica

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kusk, Anders; Kristensen, Steen Savstrup; Nielsen, Ulrik; Forsberg, René; Lin, C.-C.; Gebert, N.; Casal, T.; Davidson, M.; Bekaert, D.; Buck, C.

    In February 2011, the Polarimetric Airborne Radar Ice Sounder (POLARIS) was flown in Antarctica in order to assess the feasibility of a potential space-based radar ice sounding mission. The campaign has demonstrated that the basal return is detectable in areas with up to 3 km thick cold ice, in...

  1. A barrier radar concept

    Science.gov (United States)

    Marshall, J.; Ball, C.; Weissman, I.

    A description is given of a low power, light-weight radar that can be quickly set up and operated on batteries for extended periods of time to detect airborne intruders. With low equipment and operating costs, it becomes practical to employ a multiplicity of such radars to provide an unbroken intrusion fence over the desired perimeter. Each radar establishes a single transmitted fan beam extending vertically from horizon to horizon. The beam is generated by a two-face array antenna built in an A-frame configuration and is shaped, through phasing of the array elements, to concentrate the transmitter power in a manner consistent with the expected operating altitude ceiling of the targets of interest. The angular width of this beam in the dimension transverse to the fan depends on the radar transmission frequency and the antenna aperture dimension, but is typically wide enough so that a target at the maximum altitude or range will require tens of seconds to pass through the beam. A large number of independent samples of radar data will thus be available to provide many opportunities for target detection.

  2. Construction of a ColD <em>cda> Promoter-Based SOS-Green Fluorescent Protein Whole-Cell Biosensor with Higher Sensitivity toward Genotoxic Compounds than Constructs Based on <em>recA>, <em>umuDC>, or <em>sulA> Promoters

    DEFF Research Database (Denmark)

    Norman, Anders; Hansen, Lars Hestbjerg; Sørensen, Søren Johannes

    2005-01-01

    -methyl-N'-nitro-N-nitrosoguanidine (MNNG) revealed that the promoter for the ColD plasmid-borne cda gene had responses 12, 5, and 3 times greater than the recA, sulA, and umuDC promoters, respectively, and also considerably higher sensitivity. Furthermore, we showed that when the SOS-GFP construct was introduced into an E. coli host......Four different green fluorescent protein (GFP)-based whole-cell biosensors were created based on the DNA damage inducible SOS response of Escherichia coli in order to evaluate the sensitivity of individual SOS promoters toward genotoxic substances. Treatment with the known carcinogen N...... deficient in the tolC gene, the minimal detection limits toward mitomycin C, MNNG, nalidixic acid, and formaldehyde were lowered to 9.1 nM, 0.16 µM, 1.1 µM, and 141 µM, respectively, which were two to six times lower than those in the wild-type strain. This study thus presents a new SOS-GFP whole...

  3. 于Nios Ⅱ和HDMI的高清雷达显示系统%A High Definition Radar Display System Based on Nios Ⅱ and HDMI

    Institute of Scientific and Technical Information of China (English)

    左龙军; 李和平; 李建雄

    2011-01-01

    A high definition display card which is based on Altera' s Nios Ⅱ processor and high definition multimedia interface (HDMI) is implemented for radar systems. The card is able to transform parallel gray-scale image data into various video formats specified by CEA - 861 -D recommendation, and then display it on a LCD with HDMI or DVI interface. The highest resolution reaches 1920xl080p@60Hz. With the method of hardware and software co-design method. The flexibility of system is improved.%针对高分辨率雷达图像显示的应用,利用Altera公司提供的片上系统开发工具设计了一个基于Nios Ⅱ软核处理器和高清多媒体接口(HDMI)芯片的图像显示系统;可将并行输入的灰度图像信号转换成CEA-861-D建议规定的多种视频格式,在HDMI( DVI)显示器上滚动输出图像,分辨率最高可达1920x1080p@60Hz;通过软硬件协同设计的方法提高系统的灵活性和可扩展性.

  4. A Local Empirical Model of the E and F Region Ionosphere Based on 30 Years of Millstone Hill Incoherent Scatter Radar Data

    Science.gov (United States)

    Holt, J. M.

    2002-12-01

    Improved specifications and predictions of the ionosphere/thermosphere system are an important objective of the National Space Weather Program. As a contribution toward meeting this objective, we are developing a series of empirical models of the average behavior and variability of key parameters which characterize the ionosphere/thermosphere system. Here we present a local model of the E and F regions above Millstone Hill (42.6 N, 288.5 W) based on Millstone Hill Incoherent Scatter Radar data from 1970 to the present. The model parameters are electron density, ion temperature, electron temperature, geomagnetic-field-aligned ion drift and electric field. Time resolution is one hour, seasonal resolution is one month, altitude coverage is 100-1000 km and altitude resolution ranges from 5 km in the lower E-region to 300 km in the upper F-region. The model includes solar flux (F10.7) and geomagnetic activity (Ap) dependencies. Software to recover model values as well as a Web interface to the model is available at http://www.openmadrigal.org.

  5. Comparison of Two Methods for Estimating the Sampling-Related Uncertainty of Satellite Rainfall Averages Based on a Large Radar Data Set

    Science.gov (United States)

    Lau, William K. M. (Technical Monitor); Bell, Thomas L.; Steiner, Matthias; Zhang, Yu; Wood, Eric F.

    2002-01-01

    The uncertainty of rainfall estimated from averages of discrete samples collected by a satellite is assessed using a multi-year radar data set covering a large portion of the United States. The sampling-related uncertainty of rainfall estimates is evaluated for all combinations of 100 km, 200 km, and 500 km space domains, 1 day, 5 day, and 30 day rainfall accumulations, and regular sampling time intervals of 1 h, 3 h, 6 h, 8 h, and 12 h. These extensive analyses are combined to characterize the sampling uncertainty as a function of space and time domain, sampling frequency, and rainfall characteristics by means of a simple scaling law. Moreover, it is shown that both parametric and non-parametric statistical techniques of estimating the sampling uncertainty produce comparable results. Sampling uncertainty estimates, however, do depend on the choice of technique for obtaining them. They can also vary considerably from case to case, reflecting the great variability of natural rainfall, and should therefore be expressed in probabilistic terms. Rainfall calibration errors are shown to affect comparison of results obtained by studies based on data from different climate regions and/or observation platforms.

  6. Evolução, capacidades e limitações dos Radares Localização de Armas

    OpenAIRE

    Marrafa, Hugo

    2015-01-01

    A presente investigação destina-se a caraterizar e analisar o emprego dos radares de Localização de Armas (RLA) em ambiente operacional, utilizando o Teatro de Operações (TO) do Afeganistão como base deste estudo. Assim sendo, pretende-se analisar neste trabalho a forma como tem evoluído o emprego operacional destes meios, salientando as suas limitações, bem como evidenciando os contributos que têm fornecido para as forças presentes neste TO. Para ...

  7. Low Diversity Bacterial Community and the Trapping Activity of Metabolites from Cultivable Bacteria Species in the Female Reproductive System of the Oriental Fruit Fly, <em>Bactrocera dorsalisem> Hendel (Diptera: Tephritidae

    Directory of Open Access Journals (Sweden)

    Hongyu Zhang

    2012-05-01

    Full Text Available Our goal was to identify the bacteria inhabiting the reproductive system of the female oriental fruit fly, <em>Bactrocera dorsalisem> (Hendel, and evaluate the chemotaxis of <em>B>. <em>dorsalis> to the metabolites produced by the bacteria. Based on 16S rRNA-based polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE, 18 operational taxonomic units (OTUs were assigned to the five bacterial classes <em>Betaproteobacteria>, <em>Alphaproteobacteria>, <em>Gammaproteobacteria>, <em>Bacilli> and <em>Actinobacteria>. Nine OTUs were assigned to <em>Gammaproteobacteria>, which was the most highly represented class. <em>Enterobacteriaceae> constituted the dominant family, and within this family, three genera and five species were identified, including <em>Enterobacter sakazakiiem>, <em>Klebsiella> <em>oxytoca>, <em>Klebsiella> <em>pneumoniae,> Raoultellaem> <em>terrigena em>and <em>Enterobacter> <em>amnigenus>. In this set, the first two species were the dominant components, and the latter three species were the minor ones. Finally, we found that the metabolites produced by <em>R.> terrigenaem>, <em>K. oxytocaem> and <em>K.> pneumoniae em>were attractive to the <em>B.> dorsalisem> adults, and in field studies, <em>B.> dorsalisem> adults were most attracted to <em>K.> oxytocaem>. Collectively, our results suggest that the female reproductive system plays an important role in the transfer of enterobacteria from the gut to fruit. Our data may prompt the development of a female-targeted population control strategy for this fly.

  8. Airport Surveillance Radar : Model 7

    Data.gov (United States)

    Department of Transportation — The Airport Surveillance Radar Model 7 (ASR-7) is a short-range (60 nautical miles (nmi)) analog radar system used to detect and report the presence and location of...

  9. Airport Surveillance Radar : Model 8

    Data.gov (United States)

    Department of Transportation — The Airport Surveillance Radar Model 8 (ASR-8) is a short-range (60 nautical mile (nmi)), analog radar system used to detect and report the presence and location of...

  10. Mercury radar speckle dynamics

    Science.gov (United States)

    Holin, Igor V.

    2010-06-01

    Current data reveal that Mercury is a dynamic system with a core which has not yet solidified completely and is at least partially decoupled from the mantle. Radar speckle displacement experiments have demonstrated that the accuracy in spin-dynamics determination for Earth-like planets can approach 10 -5. The extended analysis of space-time correlation properties of radar echoes shows that the behavior of speckles does not prevent estimation of Mercury's instantaneous spin-vector components to accuracy of a few parts in 10 7. This limit can be reached with more powerful radar facilities and leads to constraining the interior in more detail from effects of spin dynamics, e.g., from observation of the core-mantle interplay through high precision monitoring of the 88-day spin-variation of Mercury's crust.

  11. The MST Radar Technique

    Science.gov (United States)

    Balsley, B. B.

    1985-01-01

    The past ten year have witnessed the development of a new radar technique to examine the structure and dynamics of the atmosphere between roughly 1 to 100 km on a continuous basis. The technique is known as the MST (for Mesosphere-Stratosphere-Troposphere) technique and is usable in all weather conditions, being unaffected by precipitation or cloud cover. MST radars make use of scattering from small scale structure in the atmospheric refractive index, with scales of the order of one-half the radar wavelength. Pertinent scale sizes for middle atmospheric studies typically range between a fraction of a meter and a few meters. The structure itself arises primarily from atmospheric turbulence. The technique is briefly described along with the meteorological parameters it measures.

  12. Radar for tracer particles

    CERN Document Server

    Ott, Felix; Huang, Kai

    2016-01-01

    We introduce a radar system capable of tracking a $5$mm spherical target continuously in three dimensions. The $10$GHz (X-band) radar system has a transmission power of $1$W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-Mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the calibration, we reconstruct the target trajectory in a three-dimensional Cartesian system. Finally, we test the tracking algorithm with target moving in circular as well as in pendulum motions, and discuss the capability of the radar system.

  13. Radar fall detectors: a comparison

    Science.gov (United States)

    Erol, Baris; Amin, Moeness; Ahmad, Fauzia; Boashash, Boualem

    2016-05-01

    Falls are a major cause of accidents in elderly people. Even simple falls can lead to severe injuries, and sometimes result in death. Doppler fall detection has drawn much attention in recent years. Micro-Doppler signatures play an important role for the Doppler-based radar systems. Numerous studies have demonstrated the offerings of micro-Doppler characteristics for fall detection. In this respect, a plethora of micro-Doppler signature features have been proposed, including those stemming from speech recognition and wavelet decomposition. In this work, we consider four different sets of features for fall detection. These can be categorized as spectrogram based features, wavelet based features, mel-frequency cepstrum coefficients, and power burst curve features. Support vector machine is employed as the classifier. Performance of the respective fall detectors is investigated using real data obtained with the same radar operating resources and under identical sensing conditions. For the considered data, the spectrogram based feature set is shown to provide superior fall detection performance.

  14. Fixed target clutter suppression by using a polarimetric FM-CW radar

    Science.gov (United States)

    Ligthart, L. P.; Nieuwkerk, L. R.; van Sinttruijen, J. S.

    The Delft FM-CW polarimetric radar is used to demonstrate capabilities of FM-CW radar systems to suppress coherent non-moving radar targets. The approach is based on measurements with multi-state polarizers. Good improvements in clutter suppression can be obtained by using fast switching polarizers for optimum elliptical polarization and dedicated polarimetry processing.

  15. Applications of FM-CW laser radar to antenna contour mapping

    Science.gov (United States)

    Slotwinski, A. R.

    1989-07-01

    The FM-CW coherent laser radar concept, based on the FM radar principle which makes use of the coherence and lunability of injection laser diodes, is discussed. Laser radar precision/time tradeoffs, block diagrams, system performance, fiber optic system implantation, and receiver improvements are briefly described.

  16. Frequency Diverse Array MIMO Radar Adaptive Beamforming with Range-Dependent Interference Suppression in Target Localization

    OpenAIRE

    Kuandong Gao; Huaizong Shao; Jingye Cai; Hui Chen; Wen-Qin Wang

    2015-01-01

    Conventional multiple-input and multiple-output (MIMO) radar is a flexible technique which enjoys the advantages of phased-array radar without sacrificing its main advantages. However, due to its range-independent directivity, MIMO radar cannot mitigate nondesirable range-dependent interferences. In this paper, we propose a range-dependent interference suppression approach via frequency diverse array (FDA) MIMO radar, which offers a beamforming-based solution to suppress range-dependent inter...

  17. Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

    Directory of Open Access Journals (Sweden)

    A. Pellinen-Wannberg

    Full Text Available Incoherent scatter radars (ISR are versatile instruments for continuous monitoring of ionisation processes in the Earth's atmosphere. EISCAT, The European Incoherent Scatter facility has proven effective also in meteor studies. The time resolution of the radar can be reduced to a few milliseconds, sufficient to resolve the passage of individual meteors through the narrow ISR beam. Methods for group and phase velocity determination of the meteoroids and the discrepancy between the results related to the target behaviour are presented. The radar cross sections of echoes associated with moving meteoroids ("meteor head echoes" are very small and increase with decreasing wavelength. The parent meteoroids are found to have visual magnitudes far below the detection limit of most optical observations. The equivalent visual magnitude limit of the smallest objects observed by EISCAT in the current experiments has been estimated by two different methods, both from the cross-section measurements and from the measured event rates. Both methods give a limit value of +10 for the smallest objects while the upper limit is +4. The lower limit of the visual magnitude for the collocated optical measurement system is +4. Thus the two detection systems observe two different meteor size ranges, with the radar almost reaching micrometeorite population. Meteor fluxes estimated from the event rates and the radar system parameters agree well with previous extrapolated values for this size range.

    Key words. Ionosphere (ionization mechanisms. Radio science (ionospheric physics. Space plasma physics (ionization processes

  18. Pricing of radar data

    OpenAIRE

    Linder, Martin; Nylin, Tobias

    2013-01-01

    In this thesis we examine the issue regarding pricing of radar data and surveillance to the operators of air navigation service (ANS) at the aerodromes in Sweden. The question of who should be responsible for providing radar data to the operators is being managed that results in if it should be LFV, as it is today, the government or another authority. This is being examined since LFV in 2010 lost its monopoly position in the terminal area in Sweden. LFV still has monopoly on the en route part...

  19. Ground penetrating radar

    CERN Document Server

    Daniels, David J

    2004-01-01

    Ground-penetrating radar has come to public attention in recent criminal investigations, but has actually been a developing and maturing remote sensing field for some time. In the light of recent expansion of the technique to a wide range of applications, the need for an up-to-date reference has become pressing. This fully revised and expanded edition of the best-selling Surface-Penetrating Radar (IEE, 1996) presents, for the non-specialist user or engineer, all the key elements of this technique, which span several disciplines including electromagnetics, geophysics and signal processing. The

  20. Radar for tracer particles

    OpenAIRE

    Ott, Felix; Herminghaus, Stephan; Huang, Kai

    2016-01-01

    We introduce a radar system capable of tracking a $5$mm spherical target continuously in three dimensions. The $10$GHz (X-band) radar system has a transmission power of $1$W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-Mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the cali...