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BACK TO INDEX Publications of year 2004 Articles in journal or book chapters
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| Abstract: | Interferometric synthetic aperture radar (InSAR) provides average height information by combining data from two parallel paths. True three-dimensional (3-D) SAR also detects the height distribution, which is of significant interest in airborne reconnaissance, forest inventory, and subsurface or wall-penetrating sensing applications as examples. In this paper, the beam performance of 3-D SAR is studied and compared for different curved line paths, such as circles, ellipses, and spirals ending up with random sampling. Curved path geometry reduces the ambiguity in height angle of traditional multipass SAR, and random path variation further improves the sidelobe suppression. The poor sidelobe suppression of a single circle path is significantly improved in near-range geometry in combination with high range resolution. By introducing a window function dependent on focus point and path position, high sidelobe suppression was achieved in an extended ground area below the circle path. |
@ARTICLE{Axelsson2004a,
author = {Axelsson, Sune R.J.},
title = {Beam characteristics of three-dimensional SAR in curved or random paths},
journal = {Geoscience and Remote Sensing, IEEE Transactions on},
year = {2004},
volume = {42},
pages = {2324--2334},
number = {10},
month = {Oct.},
abstract = {Interferometric synthetic aperture radar (InSAR) provides average height information by combining data from two parallel paths. True three-dimensional (3-D) SAR also detects the height distribution, which is of significant interest in airborne reconnaissance, forest inventory, and subsurface or wall-penetrating sensing applications as examples. In this paper, the beam performance of 3-D SAR is studied and compared for different curved line paths, such as circles, ellipses, and spirals ending up with random sampling. Curved path geometry reduces the ambiguity in height angle of traditional multipass SAR, and random path variation further improves the sidelobe suppression. The poor sidelobe suppression of a single circle path is significantly improved in near-range geometry in combination with high range resolution. By introducing a window function dependent on focus point and path position, high sidelobe suppression was achieved in an extended ground area below the circle path.},
doi = {10.1109/TGRS.2004.834802},
keywords = {SAR Processing, SAR Tomography, Tomography, Non-Linear Flight Path, Non-linear SAR},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/axelsson04Tomo.pdf},
url = {http://ieeexplore.ieee.org/iel5/36/29599/01344182.pdf}
}
Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Clutterlock, Satellite SAR, RADARSAT 1, ENVISAT, ScanSAR.
| Abstract: | We introduce a novel accurate technique to estimate the Doppler centroid (DC) in ScanSAR missions. The technique starts from the ambiguous DC measures in the subswaths and uses a method alternative to standard unwrapping to undo the jumps in estimates induced by modulo pulse repetition frequency (PRF) measures. The proposed alternative is less error prone than the usual unwrapping techniques. Doppler Ambiguity is then solved by implementing a maximum-likelihood estimate that exploits the different PRFs used in different subswaths. An azimuth pointing of the antenna that does not change with subswaths, or that changes in a known way, is assumed. However, if the PRF diversity is strong enough, unknown small changes in azimuth pointing are tolerated and accurately estimated. This estimator is much simpler and more efficient, than those in the literature. Results achieved with both RADARSAT 1 and ENVISAT ScanSAR data are reported. |
@ARTICLE{CaffGuccMonti04:Doppler,
author = {Ciro Cafforio and Pietro Guccione and Andrea Monti-Guarnieri},
title = {{Doppler Centroid Estimation for ScanSAR Data}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {2004},
volume = {42},
pages = {14-23},
number = {1},
month = Jan,
abstract = {We introduce a novel accurate technique to estimate the Doppler centroid (DC) in ScanSAR missions. The technique starts from the ambiguous DC measures in the subswaths and uses a method alternative to standard unwrapping to undo the jumps in estimates induced by modulo pulse repetition frequency (PRF) measures. The proposed alternative is less error prone than the usual unwrapping techniques. Doppler Ambiguity is then solved by implementing a maximum-likelihood estimate that exploits the different PRFs used in different subswaths. An azimuth pointing of the antenna that does not change with subswaths, or that changes in a known way, is assumed. However, if the PRF diversity is strong enough, unknown small changes in azimuth pointing are tolerated and accurately estimated. This estimator is much simpler and more efficient, than those in the literature. Results achieved with both RADARSAT 1 and ENVISAT ScanSAR data are reported.},
keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Clutterlock, Satellite SAR, RADARSAT 1, ENVISAT, ScanSAR},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/cafforioGuccioneGuarnieri04.pdf}
}
Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Satellite SAR, Geometry Models, Quality Metrics, Global Surface Fit.
| Abstract: | When Doppler centroid estimators are applied to satellite SAR data, biased estimates are often obtained because of anomalies in the received data. Typical anomalies include areas of low SNR, strong discrete targets and radiometric discontinuities. In this paper, a new method of Doppler centroid estimation is presented that takes advantage of principles such as spatial diversity, estimator quality checks, geometric models, and the fitting of a "global" estimate over a wide area of a SAR scene. In the proposed scheme, Doppler estimates are made over small blocks of data covering a whole frame, so that all parts of the scene are potentially represented. The quality of each block estimate is examined using data statistics or estimator quality measures. Poor estimates are rejected, and the remaining estimates are used to fit a surface model of the Doppler centroid versus the range and azimuth extent of the scene. A physical model that relates the satellite's orbit, attitude and beam-pointing-direction to the Doppler centroid is used to get realistic surface fits and to reduce the complexity (dimensionality) of the estimation problem. The method is tested with RADARSAT-1 and Shuttle Radar Topography Mission X-band SAR (SRTM/X-SAR) spaceborne data and is found to work well with scenes that do have radiometric anomalies, and in scenes where attitude adjustments cause the Doppler to change rapidly. |
@ARTICLE{Cumming04:DopCentrEst,
author = {Ian G. Cumming},
title = {{A Spatially Selective Approach to Doppler Estimation for Frame-Based Satellite SAR Processing}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {2004},
volume = {42},
pages = {1135-1148},
number = {6},
month = Jun,
abstract = {When Doppler centroid estimators are applied to satellite SAR data, biased estimates are often obtained because of anomalies in the received data. Typical anomalies include areas of low SNR, strong discrete targets and radiometric discontinuities. In this paper, a new method of Doppler centroid estimation is presented that takes advantage of principles such as spatial diversity, estimator quality checks, geometric models, and the fitting of a "global" estimate over a wide area of a SAR scene. In the proposed scheme, Doppler estimates are made over small blocks of data covering a whole frame, so that all parts of the scene are potentially represented. The quality of each block estimate is examined using data statistics or estimator quality measures. Poor estimates are rejected, and the remaining estimates are used to fit a surface model of the Doppler centroid versus the range and azimuth extent of the scene. A physical model that relates the satellite's orbit, attitude and beam-pointing-direction to the Doppler centroid is used to get realistic surface fits and to reduce the complexity (dimensionality) of the estimation problem. The method is tested with RADARSAT-1 and Shuttle Radar Topography Mission X-band SAR (SRTM/X-SAR) spaceborne data and is found to work well with scenes that do have radiometric anomalies, and in scenes where attitude adjustments cause the Doppler to change rapidly.},
keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Satellite SAR, Geometry Models, Quality Metrics, Global Surface Fit},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/CumDoppler04.pdf},
url = {http://ieeexplore.ieee.org/iel5/36/28983/01304880.pdf}
}
Keywords: SAR Processing, radar signal processing, spaceborne radar, synthetic aperture radar, transfer functions, EETF4, SAR geometry, X-band radar, azimuth signal accuracy requirements, erroneous Doppler parameters, fourth-order extended exact transfer function, spaceborne SAR processing, squint, synthetic aperture radar, ultra high resolution SAR.
| Abstract: | The accuracy requirements of the azimuth signal for spaceborne synthetic aperture radar (SAR) processing is analysed. Degradations of simulated extended scenes and point targets are studied at high squint or if erroneous Doppler parameters are used. At a resolution less than 1 m for X-band it is shown that the azimuth signal for spaceborne SAR geometry should be used. It is found that the fourth-order extended exact transfer function (EETF4) is a good candidate for demanding SAR processing. |
@ARTICLE{eldhuset04:EETF4,
author = {Eldhuset, Knut},
title = {Ultra high resolution spaceborne SAR processing},
journal = {Aerospace and Electronic Systems, IEEE Transactions on},
year = {2004},
volume = {40},
pages = {370--378},
number = {1},
abstract = {The accuracy requirements of the azimuth signal for spaceborne synthetic aperture radar (SAR) processing is analysed. Degradations of simulated extended scenes and point targets are studied at high squint or if erroneous Doppler parameters are used. At a resolution less than 1 m for X-band it is shown that the azimuth signal for spaceborne SAR geometry should be used. It is found that the fourth-order extended exact transfer function (EETF4) is a good candidate for demanding SAR processing.},
keywords = {SAR Processing, radar signal processing, spaceborne radar, synthetic aperture radar, transfer functions, EETF4, SAR geometry, X-band radar, azimuth signal accuracy requirements, erroneous Doppler parameters, fourth-order extended exact transfer function, spaceborne SAR processing, squint, synthetic aperture radar, ultra high resolution SAR},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/eldhuset04.pdf},
url = {http://ieeexplore.ieee.org/iel5/7/28783/01292176.pdf}
}
Keywords: SAR Processing, Hyperbolic Functions, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Stolt Mapping.
| Abstract: | This paper shows how we can use hyperbolic functions to write an exact mathematical representation of SAR imaging. This problem is primarily a geometric one, that of accounting for curved wavefronts: the spirit of this paper is to emphasize these geometrical properties over electromagnetic ones. This gives us a new and fruitful way to think about SAR imaging. Within this framework, I show how to correct for deviations of a radar from a straight flight path. This method will work even in situations where the curvature of the wavefronts is very large, where traditional methods do not. The image-formation algorithm, called omega-k migration, that results from this analysis of SAR imaging is simpler and faster than polar formatting, especially for radars with very large beamwidths as they will at very low frequencies. As an added benefit, omega-k migration is surprisingly simple to derive. |
@ARTICLE{milmanSubmitted:Hyperbolic,
author = {Andrew S. Milman},
title = {{The Hyperbolic Geometry of SAR Imaging}},
journal = {Submitted to RADIO SCIENCE},
year = {2004},
volume = {0},
pages = {0-0},
number = {0},
month = unknown,
abstract = {This paper shows how we can use hyperbolic functions to write an exact mathematical representation of SAR imaging. This problem is primarily a geometric one, that of accounting for curved wavefronts: the spirit of this paper is to emphasize these geometrical properties over electromagnetic ones. This gives us a new and fruitful way to think about SAR imaging. Within this framework, I show how to correct for deviations of a radar from a straight flight path. This method will work even in situations where the curvature of the wavefronts is very large, where traditional methods do not. The image-formation algorithm, called omega-k migration, that results from this analysis of SAR imaging is simpler and faster than polar formatting, especially for radars with very large beamwidths as they will at very low frequencies. As an added benefit, omega-k migration is surprisingly simple to derive.},
keywords = {SAR Processing, Hyperbolic Functions, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Stolt Mapping},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/milmanSubmitted.pdf},
url = {http://home.cfl.rr.com/pt/hyperbolic.pdf}
}
Keywords: SAR Processing, Fast Backprojection, Factorized Backprojection, Time Domain Backprojection, Backprojection, Moving Target Indication, Ultra-Wideband SAR, Wideband SAR, VHF SAR, UHF SAR, CARABAS, LORA, Airborne SAR, C-Band.
| Abstract: | A likelihood ratio is proposed for moving target detection in a wideband (WB) synthetic aperture radar (SAR) system. WB is defined here as any systems having a large fractional bandwidth, i.e., an ultra wide frequency band combined with a wide antenna beam. The developed method combines time-domain fast backprojection SAR processing methods with moving target detection using space-time processing. The proposed method reduces computational load when sets of relative speeds can be tested using the same clutter-suppressed subaperture beams. The proposed method is tested on narrowband radar data. |
@ARTICLE{Pettersson04:BackprojMTI,
author = {Mats I. Pettersson},
title = {{Detection of Moving Targets in Wideband SAR}},
journal = {IEEE Transactions on Aerospace and Electronic Systems},
year = {2004},
volume = {40},
pages = {780-796},
number = {3},
month = July,
abstract = {A likelihood ratio is proposed for moving target detection in a wideband (WB) synthetic aperture radar (SAR) system. WB is defined here as any systems having a large fractional bandwidth, i.e., an ultra wide frequency band combined with a wide antenna beam. The developed method combines time-domain fast backprojection SAR processing methods with moving target detection using space-time processing. The proposed method reduces computational load when sets of relative speeds can be tested using the same clutter-suppressed subaperture beams. The proposed method is tested on narrowband radar data.},
comment = {Developed for wideband systems (CARABAS, LORA) but tested using airborne C-Band data (Andover system, center freq: 5.7 GHz, bandwidth: 82 Mhz, antenna beamwidth: 8 deg)},
keywords = {SAR Processing, Fast Backprojection, Factorized Backprojection, Time Domain Backprojection, Backprojection, Moving Target Indication, Ultra-Wideband SAR, Wideband SAR, VHF SAR,UHF SAR, CARABAS, LORA, Airborne SAR, C-Band},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/Pettersson04.pdf},
url = {http://ieeexplore.ieee.org/iel5/7/29502/01337454.pdf}
}
Keywords: SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, synthetic aperture radar, airborne L-band repeat-pass interferometry, airborne SAR interferograms, azimuth registration errors, interpolation-free coregistration, navigation system, phase azimuth undulations, residual motion error correction, spectral diversity technique, synthetic aperture radar, Calibration, SAR, image registration, interferometry, Motion Compensation, repeat-pass interferometry, synthetic aperture radar.
| Abstract: | This letter discusses the detection and correction of residual motion errors that appear in airborne synthetic aperture radar (SAR) interferograms due to the lack of precision in the navigation system. As it is shown, the effect of this lack of precision is twofold: azimuth registration errors and phase azimuth undulations. Up to now, the correction of the former was carried out by estimating the registration error and interpolating, while the latter was based on the estimation of the phase azimuth undulations to compensate the phase of the computed interferogram. In this letter, a new correction method is proposed, which avoids the interpolation step and corrects at the same time the azimuth phase undulations. Additionally, the spectral diversity technique, used to estimate registration errors, is critically analyzed. Airborne L-band repeat-pass interferometric data of the German Aerospace Center (DLR) experimental airborne SAR is used to validate the method. |
@ARTICLE{pratsReigberMallorqui04:InterpolFreeCoregistration,
author = {Prats, Pau and Reigber, Andreas and Mallorqui, Jordi J.},
title = {{Interpolation-free coregistration and phase-correction of airborne SAR interferograms}},
journal = {Geoscience and Remote Sensing Letters, IEEE},
year = {2004},
volume = {1},
pages = {188--191},
number = {3},
abstract = {This letter discusses the detection and correction of residual motion errors that appear in airborne synthetic aperture radar (SAR) interferograms due to the lack of precision in the navigation system. As it is shown, the effect of this lack of precision is twofold: azimuth registration errors and phase azimuth undulations. Up to now, the correction of the former was carried out by estimating the registration error and interpolating, while the latter was based on the estimation of the phase azimuth undulations to compensate the phase of the computed interferogram. In this letter, a new correction method is proposed, which avoids the interpolation step and corrects at the same time the azimuth phase undulations. Additionally, the spectral diversity technique, used to estimate registration errors, is critically analyzed. Airborne L-band repeat-pass interferometric data of the German Aerospace Center (DLR) experimental airborne SAR is used to validate the method.},
keywords = {SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, synthetic aperture radar, airborne L-band repeat-pass interferometry, airborne SAR interferograms, azimuth registration errors, interpolation-free coregistration, navigation system, phase azimuth undulations, residual motion error correction, spectral diversity technique, synthetic aperture radar, Calibration, SAR, image registration, interferometry, Motion Compensation, repeat-pass interferometry, synthetic aperture radar},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/pratsReigberMallorqui04.pdf},
url = {http://ieeexplore.ieee.org/iel5/8859/29155/01315629.pdf}
}
Keywords: SAR Processing, Non-linear Flight Path, SAR Tomography, Curvilinear SAR, Bistatic SAR, airborne radar, image reconstruction, parameter estimation, radar imaging, synthetic aperture radar, 3-D scene reconstruction, bistatic SAR, data collection strategy, flight path strategies, nonlinear receiver trajectory, nonparametric scene reconstructions, phase history, receiver flight paths, three-dimensional information, three-dimensional scattering centre location parameter estimates, three-dimensional scene information.
| Abstract: | Proper design of receiver flight paths allows three-dimensional information to be encoded in sensed bistatic SAR phase history data. The authors show how the flight path taken by the receiving platform determines the resolution of nonparametric scene reconstructions and determines the variance of three-dimensional scattering centre location parameter estimates. Based on these relationships, a bistatic SAR data collection strategy can be designed, involving a nonlinear receiver trajectory that allows preservation of three-dimensional scene information. |
@ARTICLE{riglingMoses2004:BistaticNonLinearSARTomo,
author = {Rigling, B.D. and Moses, R.L.},
title = {Flight path strategies for 3-D scene reconstruction from bistatic SAR},
journal = {Radar, Sonar and Navigation, IEE Proceedings -},
year = {2004},
volume = {151},
pages = {149--157},
number = {3},
abstract = {Proper design of receiver flight paths allows three-dimensional information to be encoded in sensed bistatic SAR phase history data. The authors show how the flight path taken by the receiving platform determines the resolution of nonparametric scene reconstructions and determines the variance of three-dimensional scattering centre location parameter estimates. Based on these relationships, a bistatic SAR data collection strategy can be designed, involving a nonlinear receiver trajectory that allows preservation of three-dimensional scene information.},
booktitle = {Radar, Sonar and Navigation, IEE Proceedings -},
issn = {1350-2395},
keywords = {SAR Processing, Non-linear Flight Path, SAR Tomography, Curvilinear SAR, Bistatic SAR, airborne radar, image reconstruction, parameter estimation, radar imaging, synthetic aperture radar, 3-D scene reconstruction, bistatic SAR, data collection strategy, flight path strategies, nonlinear receiver trajectory, nonparametric scene reconstructions, phase history, receiver flight paths, three-dimensional information, three-dimensional scattering centre location parameter estimates, three-dimensional scene information},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/riglingMoses2004.pdf},
url = {http://ieeexplore.ieee.org/iel5/2198/29130/01312057.pdf}
}
Keywords: SAR Processing, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar, Backprojection, Time-Domain Backprojection, Fast Backprojection, Bistatic SAR, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, Polar Format Algorithm, synthetic aperture radar.
| Abstract: | Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N/sup 2/ log/sub 2/N) performance. An O(N/sup 2/ log/sub 2/N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA. |
@ARTICLE{riglingMoses04:PFABackproj,
author = {Rigling, Brian D. and Moses, Randolph L.},
title = {Polar format algorithm for bistatic SAR},
journal = {Aerospace and Electronic Systems, IEEE Transactions on},
year = {2004},
volume = {40},
pages = {1147--1159},
number = {4},
abstract = {Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N/sup 2/ log/sub 2/N) performance. An O(N/sup 2/ log/sub 2/N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.},
keywords = {SAR Processing, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar, Backprojection, Time-Domain Backprojection, Fast Backprojection, Bistatic SAR, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, Polar Format Algorithm, synthetic aperture radar},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/riglingMoses04.pdf},
url = {http://ieeexplore.ieee.org/iel5/7/30189/01386870.pdf}
}
Keywords: SAR Processing, Bistatic SAR, backprojection algorithms, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, polar format algorithm, synthetic aperture radar, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar;.
| Abstract: | Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N2 log2N) performance. An O(N2 log2N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA. |
@ARTICLE{RiglingMoses2004:BiStaticPolarFormat,
author={Rigling, B.D. and Moses, R.L.},
journal=IEEE_J_AES,
title={Polar format algorithm for bistatic {SAR}},
year={2004},
month=oct,
volume={40},
number={4},
pages={1147-1159},
abstract={Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N2 log2N) performance. An O(N2 log2N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.},
keywords={SAR Processing,Bistatic SAR, backprojection algorithms; bistatic far-field assumption; matched filtering; monostatic SAR image formation; phase history data; polar format algorithm; synthetic aperture radar; backpropagation; computational complexity; matched filters; radar imaging; synthetic aperture radar;},
doi={10.1109/TAES.2004.1386870},
ISSN={0018-9251},
}
Keywords: SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR, fast Fourier transforms, feature extraction, radar imaging, synthetic aperture radar, Cramer-Rao bounds, LODIPS algorithm, RELAX algorithm, SNR, computational load, curvilinear synthetic aperture radar system, lower dimensional FFT, lower dimensional position searching, three dimensional target feature extraction.
| Abstract: | A lower dimensional position searching (LODIPS) algorithm is proposed for three-dimensional (3-D) target feature extraction via the curvilinear synthetic aperture radar (CLSAR) system. Compared with another similarly structured algorithm RELAX, the LODIPS algorithm dramatically reduces the computational load through the utilisation of lower dimensional FFTs. Simulation results show that the new algorithm can reach CRB at low SNR. |
@ARTICLE{suPengWang2004:NonLinearSARTomo,
author = {Su, Z. and Peng, Y. and Wang, X.},
title = {Efficient algorithm for three-dimensional target feature extraction via CLSAR},
journal = {Electronics Letters},
year = {2004},
volume = {40},
pages = {965--966},
number = {15},
abstract = {A lower dimensional position searching (LODIPS) algorithm is proposed for three-dimensional (3-D) target feature extraction via the curvilinear synthetic aperture radar (CLSAR) system. Compared with another similarly structured algorithm RELAX, the LODIPS algorithm dramatically reduces the computational load through the utilisation of lower dimensional FFTs. Simulation results show that the new algorithm can reach CRB at low SNR.},
booktitle = {Electronics Letters},
issn = {0013-5194},
keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR, fast Fourier transforms, feature extraction, radar imaging, synthetic aperture radar, Cramer-Rao bounds, LODIPS algorithm, RELAX algorithm, SNR, computational load, curvilinear synthetic aperture radar system, lower dimensional FFT, lower dimensional position searching, three dimensional target feature extraction},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/suPengWang2004.pdf},
url = {http://ieeexplore.ieee.org/iel5/2220/29231/01318899.pdf}
}
Keywords: SAR Processing, InSAR, SAR Interferometry, Forest, remote sensing, carbon cycle, LiDAR, optical remote sensing, forest ecology, SAR Tomography.
| Abstract: | The possibility of global, three-dimensional remote sensing of forest structure with interferometric synthetic aperture radar (InSAR) bears on important forest ecological processes, particularly the carbon cycle. InSAR supplements two-dimensional remote sensing with information in the vertical dimension. Its strengths in potential for global coverage complement those of lidar (light detecting and ranging), which has the potential for high-accuracy vertical profiles over small areas. InSAR derives its sensitivity to forest vertical structure from the differences in signals received by two, spatially separate radar receivers. Estimation of parameters describing vertical structure requires multiple-polarization, multiple-frequency, or multiple-baseline InSAR. Combining InSAR with complementary remote sensing techniques, such as hyperspectral optical imaging and lidar, can enhance vertical-structure estimates and consequent biophysical quantities of importance to ecologists, such as biomass. Future InSAR experiments will supplement recent airborne and spaceborne demonstrations, and together with inputs from ecologists regarding structure, they will suggest designs for future spaceborne strategies for measuring global vegetation structure. |
@ARTICLE{treuhaftLawAsner2004:ForestAttributeFromInSAR,
author = {Robert N. Treuhaft and Beverly E. Law and Gregory P. Asner},
title = {Forest Attributes from Radar Interferometric Structure and Its Fusion with Optical Remote Sensing},
journal = {BioScience},
year = {2004},
volume = {54},
pages = {561--571},
number = {6},
abstract = {The possibility of global, three-dimensional remote sensing of forest structure with interferometric synthetic aperture radar (InSAR) bears on important forest ecological processes, particularly the carbon cycle. InSAR supplements two-dimensional remote sensing with information in the vertical dimension. Its strengths in potential for global coverage complement those of lidar (light detecting and ranging), which has the potential for high-accuracy vertical profiles over small areas. InSAR derives its sensitivity to forest vertical structure from the differences in signals received by two, spatially separate radar receivers. Estimation of parameters describing vertical structure requires multiple-polarization, multiple-frequency, or multiple-baseline InSAR. Combining InSAR with complementary remote sensing techniques, such as hyperspectral optical imaging and lidar, can enhance vertical-structure estimates and consequent biophysical quantities of importance to ecologists, such as biomass. Future InSAR experiments will supplement recent airborne and spaceborne demonstrations, and together with inputs from ecologists regarding structure, they will suggest designs for future spaceborne strategies for measuring global vegetation structure.},
keywords = {SAR Processing, InSAR, SAR Interferometry, Forest, remote sensing, carbon cycle, LiDAR, optical remote sensing, forest ecology, SAR Tomography},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/treuhaftLawAsner2004.pdf}
}
Conference articles
-
Emmanouil Alivizatos,
Athanasios Potsis,
Andreas Reigber,
Alberto Moreira,
and Nikolaos K. Uzunoglou.
SAR Processing with Motion Compensation using the Extended Wavenumber Algorithm.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
pages 157-160,
2004.
Keywords: SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR.Abstract: Modern Synthetic Aperture Radar (SAR) systems are continuously developing into the direction of higher spatial resolution and new modes of operation. This requires the use of high bandwidths, combined with wide azimuthal integration intervals. For focusing such data, a high quality SAR processing method is necessary, which is able to deal with more general sensor parameters. Wavenumber domain (Omega-K) processing is commonly accepted to be an ideal solution of the SAR focusing problem [1]. However, it is mostly applicable on spaceborne SAR data where a straight sensor trajectory is given. In case of airborne SAR data, wavenumber domain processing has certain limitations in performing high-precision motion compensation. In this paper, a detailed description of the motion errors in the wavenumber domain, as well as a motion compensation technique in this domain is formulated. The correction of the motion errors in the two dimensional spectral domain can result in very accurate second order motion compensation. This procedure can also be combined with a 2D sub-aperture technique, which results in a fully azimuth-frequency adaptive block processing scheme. The reason why the wavenumber MoCo can be very critical especially in low frequency-widebeam and high squinted SAR data, is that in these cases wavelength dependent corrections become mandatory. @INPROCEEDINGS{AlivizatosReigberMoreiraUzunoglu04:ExtendedOmegaK, author = {Emmanouil Alivizatos and Athanasios Potsis and Andreas Reigber and Alberto Moreira and Nikolaos K. Uzunoglou}, title = {SAR Processing with Motion Compensation using the Extended Wavenumber Algorithm}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {157-160}, abstract = {Modern Synthetic Aperture Radar (SAR) systems are continuously developing into the direction of higher spatial resolution and new modes of operation. This requires the use of high bandwidths, combined with wide azimuthal integration intervals. For focusing such data, a high quality SAR processing method is necessary, which is able to deal with more general sensor parameters. Wavenumber domain (Omega-K) processing is commonly accepted to be an ideal solution of the SAR focusing problem [1]. However, it is mostly applicable on spaceborne SAR data where a straight sensor trajectory is given. In case of airborne SAR data, wavenumber domain processing has certain limitations in performing high-precision motion compensation. In this paper, a detailed description of the motion errors in the wavenumber domain, as well as a motion compensation technique in this domain is formulated. The correction of the motion errors in the two dimensional spectral domain can result in very accurate second order motion compensation. This procedure can also be combined with a 2D sub-aperture technique, which results in a fully azimuth-frequency adaptive block processing scheme. The reason why the wavenumber MoCo can be very critical especially in low frequency-widebeam and high squinted SAR data, is that in these cases wavelength dependent corrections become mandatory.}, keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/AlivizatosReigberMoreiraUzunoglu04.pdf} } -
Elke Boerner,
Hauke Fiedler,
Gerhard Krieger,
and Josef Mittermayer.
A new Method for Total Zero Doppler Steering.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, Steering, Yaw Steering, Attitude Steering, Doppler Centroid, Zero Doppler Steering, Total Zero Doppler Steering.Abstract: This paper describes a new method to perform zero Doppler steering, namely Total Zero Doppler Steering. It is developed for spaceborne synthetic aperture radar (SAR) systems. This new method combines the yaw-steering with an additional pitch-steering, resulting in a Doppler centroid of theoretically zero Hertz over the whole desired range of incidence angles for the whole orbit and simultaneously for left and right looking geometry. @INPROCEEDINGS{BoernerFiedlerKriegerMittermayer04:Doppler, author = {Elke Boerner and Hauke Fiedler and Gerhard Krieger and Josef Mittermayer}, title = {{A new Method for Total Zero Doppler Steering}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {This paper describes a new method to perform zero Doppler steering, namely Total Zero Doppler Steering. It is developed for spaceborne synthetic aperture radar (SAR) systems. This new method combines the yaw-steering with an additional pitch-steering, resulting in a Doppler centroid of theoretically zero Hertz over the whole desired range of incidence angles for the whole orbit and simultaneously for left and right looking geometry.}, keywords = {SAR Processing, Steering, Yaw Steering, Attitude Steering, Doppler Centroid, Zero Doppler Steering, Total Zero Doppler Steering}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/BoernerFiedlerKriegerMittermayer04.pdf} } -
F. Bordoni,
A. Jakobsson,
F. Lombardini,
and F. Gini.
Layover solution in multibaseline InSAR using interpolated arrays.
In Proceedings of the Fourth IEEE International Symposium on Signal Processing and Information Technology, 2004,
pages 175--178,
2004.
Keywords: SAR Processing, Interferometry, SAR Tomography, Tomography, Layover, Array Interpolation, MUSIC, WSF.Abstract: This work deals with the problem of direction of direction of arrival estimation of interferometric synthetic aperture radar (InSAR) signals in presence of layover. The focus here is on realistic acquisition systems with a low number of phase centres and nonuniform array geometry. An interpolated array approach is proposed, in order to apply spectral estimation techniques designed for uniform linear arrays. In particular, interpolated MUSIC and weighted subspace fitting (WSF) algorithms are developed and investigated. @INPROCEEDINGS{bordoniJakobssonLombardiniGini04:, author = {Bordoni, F. and Jakobsson, A. and Lombardini, F. and Gini, F.}, title = {Layover solution in multibaseline InSAR using interpolated arrays}, booktitle = {Proceedings of the Fourth IEEE International Symposium on Signal Processing and Information Technology, 2004}, year = {2004}, pages = {175--178}, abstract = {This work deals with the problem of direction of direction of arrival estimation of interferometric synthetic aperture radar (InSAR) signals in presence of layover. The focus here is on realistic acquisition systems with a low number of phase centres and nonuniform array geometry. An interpolated array approach is proposed, in order to apply spectral estimation techniques designed for uniform linear arrays. In particular, interpolated MUSIC and weighted subspace fitting (WSF) algorithms are developed and investigated.}, keywords = {SAR Processing, Interferometry, SAR Tomography, Tomography, Layover, Array Interpolation, MUSIC, WSF}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/bordoniJakobssonLombardiniGini04.pdf}, url = {http://ieeexplore.ieee.org/iel5/9800/30910/01433715.pdf} } -
Knut Eldhuset.
Raw signal simulation for very high resolution SAR based on polarimetric scattering theory.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Polarimetric Scattering Theory.Abstract: A method for raw signal simulation for extended SAR scenes with very high resolution is described. This simulator shall handle resolution better than 1 m, squinted geometry, elliptical orbit motion and use a polarimetric reflectivity matrix. Classical polarimetric scattering theory is based on electromagnetic harmonic fields using Maxwell s equations, Green s function, Huygens principle and Kirchhoff s approximation. Here, the scattering theory is modified for a chirp field. Calculated expressions for the scattered chirp field or the reflectivity matrix are presented. Such a reflectivity matrix can then be input to the inverse-EETF4 for raw data generation. @INPROCEEDINGS{Eldhuset04:Simulation, author = {Knut Eldhuset}, title = {{Raw signal simulation for very high resolution SAR based on polarimetric scattering theory}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {A method for raw signal simulation for extended SAR scenes with very high resolution is described. This simulator shall handle resolution better than 1 m, squinted geometry, elliptical orbit motion and use a polarimetric reflectivity matrix. Classical polarimetric scattering theory is based on electromagnetic harmonic fields using Maxwell s equations, Green s function, Huygens principle and Kirchhoff s approximation. Here, the scattering theory is modified for a chirp field. Calculated expressions for the scattered chirp field or the reflectivity matrix are presented. Such a reflectivity matrix can then be input to the inverse-EETF4 for raw data generation.}, keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Polarimetric Scattering Theory}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/Eldhuset04IGARSS.pdf} } -
Joachim H. G. Ender,
I. Walterscheid,
and Andreas R. Brenner.
New aspects of bistatic SAR: processing and experiments.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, Bistatic SAR, Bistatic Processing, Backprojection, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Airborne SAR.Abstract: The interest in bistatic synthetic aperture radar, using separated transmitter and receiver flying on different platforms, has been increasing rapidly over the last years. The reason for this are specific advantages, like the reduced vulnerability in military systems, forward looking SAR imaging, additional information about the target, or increased RCS (see e.g. [1]). Nevertheless, besides technical problems (see [2]) - like the synchronisation of the oscillators, the involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, double trajectory measurement and motion compensation - the processing of bistatic radar data is still not sufficiently solved. Some of the possibilities and problems will be discussed. The second part of this paper deals with a bistatic experiment performed in November 2003: Two SAR systems of FGAN have been flown on two different airplanes, the AER-II system has been used as a transmitter and the PAMIR system as a receiver. Different spatially invariant flight geometries have been tested. High resolution bistatic SAR images were generated successfully. @INPROCEEDINGS{EnderWalterscheidBrenner04:bistaticSAR, author = {Joachim H. G. Ender and I. Walterscheid and Andreas R. Brenner}, title = {{New aspects of bistatic SAR: processing and experiments}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {The interest in bistatic synthetic aperture radar, using separated transmitter and receiver flying on different platforms, has been increasing rapidly over the last years. The reason for this are specific advantages, like the reduced vulnerability in military systems, forward looking SAR imaging, additional information about the target, or increased RCS (see e.g. [1]). Nevertheless, besides technical problems (see [2]) - like the synchronisation of the oscillators, the involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, double trajectory measurement and motion compensation - the processing of bistatic radar data is still not sufficiently solved. Some of the possibilities and problems will be discussed. The second part of this paper deals with a bistatic experiment performed in November 2003: Two SAR systems of FGAN have been flown on two different airplanes, the AER-II system has been used as a transmitter and the PAMIR system as a receiver. Different spatially invariant flight geometries have been tested. High resolution bistatic SAR images were generated successfully.}, keywords = {SAR Processing, Bistatic SAR, Bistatic Processing, Backprojection, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Airborne SAR}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/EnderWalterscheidBrenner04.pdf} } -
G. Fornaro,
Giorgio Franceschetti,
and S. Perna.
Motion Compensation of Squinted Airborne SAR Raw Data: Role of Processing Geometry.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR.Abstract: We discuss the role of processing geometry and the problem of motion compensation for non zero squint in airborne SAR processing. @INPROCEEDINGS{franceschettiPernaFornaro04:Moco, author = {G. Fornaro and Giorgio Franceschetti and S. Perna}, title = {{Motion Compensation of Squinted Airborne SAR Raw Data: Role of Processing Geometry}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {We discuss the role of processing geometry and the problem of motion compensation for non zero squint in airborne SAR processing.}, keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/franceschettiPernaFornaro04.pdf} } -
G. Fornaro and F. Serafino.
Spaceborne 3D SAR Tomography: experiments with ERS data.
In Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International,
volume 2,
pages 1240--1243,
2004.
Keywords: SAR Processing, SAR Tomography, Tomography, data acquisition, image processing, radar cross-sections, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, tomography, 3D back-scattering property, ERS data, European Remote Sensing, multibaseline SAR experiment, spaceborne 3D SAR tomography.Abstract: This paper presents the first results of a multibaseline SAR experiments for the reconstruction of the 3D back-scattering properties of ground scenes by using ERS data. @INPROCEEDINGS{fornaroSerafino04:Tomo, author = {Fornaro, G. and Serafino, F.}, title = {Spaceborne 3D SAR Tomography: experiments with ERS data}, booktitle = {Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International}, year = {2004}, volume = {2}, pages = {1240--1243}, abstract = {This paper presents the first results of a multibaseline SAR experiments for the reconstruction of the 3D back-scattering properties of ground scenes by using ERS data.}, keywords = {SAR Processing, SAR Tomography, Tomography, data acquisition, image processing, radar cross-sections, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, tomography, 3D back-scattering property, ERS data, European Remote Sensing, multibaseline SAR experiment, spaceborne 3D SAR tomography}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/fornaroSerafinoTomo04.pdf}, url = {http://ieeexplore.ieee.org/iel5/9436/29945/01368640.pdf} } -
Othmar Frey,
Erich Meier,
Daniel Nüesch,
and Achim Roth.
Geometric Error Budget Analysis for TerraSAR-X.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
Ulm, Germany,
pages 513-516,
May 25-27 2004.
Keywords: SAR Processing, SAR Geocoding, Geocoding, Error Budget Analysis, TerraSAR-X, Atmospheric Correction, Atmospheric Path Delay, Ionosheric Path Delay, Antenna Gain Pattern Correction.Abstract: The impact of potential error sources on geocoded products has been investigated with respect to the high resolution capabilities of the TerraSAR-X sensor. Datum shift parameters, maps, digital terrain and surface models have been identified as external error sources. The accuracy of the geocoded products depends heavily on the quality and availability of this information, which underlies regional variations. Error sources closely related to the sensor are its position, sampling window start time and Doppler centroid frequency. Another error source is given by atmospheric refraction. Ionospheric and atmospheric path delays have a considerable impact. Appropriate modeling can mitigate this effect. Further, high requirements on radiometric accuracy ask for an improved antenna gain pattern correction, which depends on the actual elevation angle and the terrain height. @INPROCEEDINGS{freyMeierNueeschRoth04:ErrorBudget, author = {Othmar Frey and Erich Meier and Daniel N{\"u}esch and Achim Roth}, title = {{Geometric Error Budget Analysis for TerraSAR-X}}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {513-516}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {The impact of potential error sources on geocoded products has been investigated with respect to the high resolution capabilities of the TerraSAR-X sensor. Datum shift parameters, maps, digital terrain and surface models have been identified as external error sources. The accuracy of the geocoded products depends heavily on the quality and availability of this information, which underlies regional variations. Error sources closely related to the sensor are its position, sampling window start time and Doppler centroid frequency. Another error source is given by atmospheric refraction. Ionospheric and atmospheric path delays have a considerable impact. Appropriate modeling can mitigate this effect. Further, high requirements on radiometric accuracy ask for an improved antenna gain pattern correction, which depends on the actual elevation angle and the terrain height.}, keywords = {SAR Processing,SAR Geocoding,Geocoding,Error Budget Analysis,TerraSAR-X,Atmospheric Correction,Atmospheric Path Delay,Ionosheric Path Delay,Antenna Gain Pattern Correction}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/myPublications/PAPERS/freyMeierNueeschRoth04.pdf} } -
F. Gini and F. Lombardini.
Multibaseline post-processing for SAR interferometry.
In Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004,
pages 20--29,
2004.
Keywords: SAR Processing, SAR Tomography, Tomography, radar detection, radar imaging, radiowave interferometry, synthetic aperture radar, 3D mapping, XTI-SAR, additive white Gaussian noise, cross-track InSAR system, multibaseline InSAR processing, multicomponent signal corruption estimation, multiplicative noise, radar reflectivity retrieval, semitransparent volume scattering layer, signal detection, synthetic aperture radar, tomography.Abstract: In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights and radar reflectivities of natural layover areas by means of a cross-track InSAR (XTI-SAR) system. It is formulated as the problem of detecting and estimating a multicomponent signal corrupted by multiplicative noise and by additive white Gaussian noise. The problem of estimating the number of signal components in the presence of speckle is also addressed. Finally, a brief mention is given to recent research trends on robust methods for non-perfectly calibrated arrays and on MB-SAR tomography, which is an extension of MB-InSAR for full 3D mapping of semitransparent volume scattering layers. @INPROCEEDINGS{giniLombardini04:Tomo, author = {Gini, F. and Lombardini, F.}, title = {Multibaseline post-processing for SAR interferometry}, booktitle = {Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004}, year = {2004}, pages = {20--29}, abstract = {In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights and radar reflectivities of natural layover areas by means of a cross-track InSAR (XTI-SAR) system. It is formulated as the problem of detecting and estimating a multicomponent signal corrupted by multiplicative noise and by additive white Gaussian noise. The problem of estimating the number of signal components in the presence of speckle is also addressed. Finally, a brief mention is given to recent research trends on robust methods for non-perfectly calibrated arrays and on MB-SAR tomography, which is an extension of MB-InSAR for full 3D mapping of semitransparent volume scattering layers.}, keywords = {SAR Processing, SAR Tomography, Tomography, radar detection, radar imaging, radiowave interferometry, synthetic aperture radar, 3D mapping, XTI-SAR, additive white Gaussian noise, cross-track InSAR system, multibaseline InSAR processing, multicomponent signal corruption estimation, multiplicative noise, radar reflectivity retrieval, semitransparent volume scattering layer, signal detection, synthetic aperture radar, tomography}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/giniLombardiniTomo04.pdf}, url = {http://ieeexplore.ieee.org/iel5/10049/32242/01502903.pdf} } -
B. Hallberg,
G. Smith,
A. Olofsson,
and Lars M. H. Ulander.
Performance Simulation of Spaceborne P-band SAR for Global Biomass Retrieval.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, Simulation, P-Band, Biomass Retrieval, Forest.Abstract: This paper evaluates the use of a spaceborne lowfrequency synthetic aperture radar (SAR) for forest biomass retrieval. Airborne radar data are used as input to a SAR simulator in which SAR system parameters of the assumed spaceborne system and propagation effects in the ionosphere (primarily scintillation and Faraday rotation) are modelled. The simulations are performed for different iononospheric perturbation states. Some simulated spaceborne low-frequency SAR images over boreal forest are shown and their usefulness for forest biomass retrieval are studied and discussed. The results indicate that it is possible to separate boreal forest into three classes assuming a moderate distorted ionosphere. @INPROCEEDINGS{HallbergSmithOlofssonUlander04:Simulation, author = {B. Hallberg and G. Smith and A. Olofsson and Lars M. H. Ulander}, title = {{Performance Simulation of Spaceborne P-band SAR for Global Biomass Retrieval}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {This paper evaluates the use of a spaceborne lowfrequency synthetic aperture radar (SAR) for forest biomass retrieval. Airborne radar data are used as input to a SAR simulator in which SAR system parameters of the assumed spaceborne system and propagation effects in the ionosphere (primarily scintillation and Faraday rotation) are modelled. The simulations are performed for different iononospheric perturbation states. Some simulated spaceborne low-frequency SAR images over boreal forest are shown and their usefulness for forest biomass retrieval are studied and discussed. The results indicate that it is possible to separate boreal forest into three classes assuming a moderate distorted ionosphere.}, keywords = {SAR Processing, Simulation, P-Band, Biomass Retrieval, Forest}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/HallbergSmithOlofssonUlander04.pdf} } -
Charles V. Jakowatz,
Daniel E. Wahl,
David A. Yocky,
Brian K. Bray,
Wallace J. Bow,
and John A. Richards.
Comparison of algorithms for use in real-time spotlight-mode SAR image formation.
In Edmund G. Zelnio and Frederick D. Garber, editors,
,
volume 5427,
pages 108-116,
2004.
SPIE.
Keywords: SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA, Range Migration Algorithm, RMA, omega-k, Comparison of Algorithms, Comparison of Focusing Algorithms, overlapped subaperture algorithm, OSA, Spotlight SAR, Spotlight-mode data.@conference{jakowatzWahlYockyBrayBowRichardsSpotlightComparisonOfAlgorithms2004, author = {Charles V. Jakowatz, Jr. and Daniel E. Wahl and David A. Yocky and Brian K. Bray and Wallace J. Bow, Jr. and John A. Richards}, editor = {Edmund G. Zelnio and Frederick D. Garber}, collaboration = {}, title = {Comparison of algorithms for use in real-time spotlight-mode {SAR} image formation}, publisher = {SPIE}, year = {2004}, journal = {Algorithms for Synthetic Aperture Radar Imagery XI}, volume = {5427}, number = {1}, pages = {108-116}, location = {Orlando, FL, USA}, url = {http://link.aip.org/link/?PSI/5427/108/1}, doi = {10.1117/12.548203}, keywords = {SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA, Range Migration Algorithm, RMA, omega-k, Comparison of Algorithms, Comparison of Focusing Algorithms, overlapped subaperture algorithm, OSA, Spotlight SAR, Spotlight-mode data}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/jakowatzWahlYockyBrayBowRichardsSpotlightComparisonOfAlgorithms2004.pdf}, owner = {ofrey}, } -
Michael Jehle,
Othmar Frey,
David Small,
Erich Meier,
and Daniel Nüesch.
Improved Knowledge of SAR Geometry through Atmospheric Modelling.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
Ulm, Germany,
pages 909-911,
May 25-27 2004.
Keywords: Geocoding, Geometry, Atmospheric Path Delay, Ionosheric Path Delay, Tropospheric Path Delay, Atmospheric Modelling.Abstract: Satellites observing and measuring the Earth s surface with electromagnetic waves are subject to atmospheric path delays. These atmospheric effects on radar signal propagation modify the signal velocity and direction and can be considered by simple modeling. In order to increase the geolocation accuracy of spaceborne SAR applications we developed a software tool that accounts for atmospheric path delays. Well-calibrated spaceborne ENVISAT-ASAR data are used to investigate improvements to knowledge of the geometry of the scene. @INPROCEEDINGS{jehleFreySmallMeierNueesch04:Atmosphere, author = {Michael Jehle and Othmar Frey and David Small and Erich Meier and Daniel N{\"u}esch}, title = {Improved Knowledge of SAR Geometry through Atmospheric Modelling}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {909-911}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {Satellites observing and measuring the Earth s surface with electromagnetic waves are subject to atmospheric path delays. These atmospheric effects on radar signal propagation modify the signal velocity and direction and can be considered by simple modeling. In order to increase the geolocation accuracy of spaceborne SAR applications we developed a software tool that accounts for atmospheric path delays. Well-calibrated spaceborne ENVISAT-ASAR data are used to investigate improvements to knowledge of the geometry of the scene.}, keywords = {Geocoding, Geometry,Atmospheric Path Delay,Ionosheric Path Delay,Tropospheric Path Delay,Atmospheric Modelling}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/myPublications/PAPERS/jehleFreySmallMeierNueesch04.pdf} } -
David Kettler,
Doug Gray,
and Nick Redding.
The Point Spread Function for UWB SAR Imaging using Inversion of the Circular Radon Transform.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
Ulm, Germany,
pages 175-178,
May 25-27 2004.
Keywords: SAR Processing, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Circular Radon Transform, CRT, Radon Transform, Ultra-Wideband SAR, Airborne SAR.Abstract: This paper summarises how SAR data collection can be viewed as taking the Circular Radon Transform of the ground reflectivity and outlines how image formation can be achieved by inverting the CRT via a Fourier-Hankel transform. An expression for the point spread function (PSF) of the imaging process is arrived at by means of an analytic inversion for a Gaussian. This PSF shows the effect on the image of the finite synthetic aperture. Illustrations of the PSF to show its range and aperture dependence are given. @INPROCEEDINGS{kettlerGrayRedding04:Hankel, author = {David Kettler and Doug Gray and Nick Redding}, title = {The Point Spread Function for UWB SAR Imaging using Inversion of the Circular Radon Transform}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {175-178}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {This paper summarises how SAR data collection can be viewed as taking the Circular Radon Transform of the ground reflectivity and outlines how image formation can be achieved by inverting the CRT via a Fourier-Hankel transform. An expression for the point spread function (PSF) of the imaging process is arrived at by means of an analytic inversion for a Gaussian. This PSF shows the effect on the image of the finite synthetic aperture. Illustrations of the PSF to show its range and aperture dependence are given.}, keywords = {SAR Processing, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Circular Radon Transform, CRT, Radon Transform, Ultra-Wideband SAR, Airborne SAR}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/kettlerGrayRedding04.pdf} } -
John C. Kirk,
Don Woods,
and Joe Salzman.
Efficient Motion-Tolerant Fopen SAR Processing.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
volume 1,
Ulm, Germany,
pages 179-182,
May 25-27 2004.
Keywords: SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Motion Compensation, Thinned Range Migration Algorithm, Airborne SAR.Abstract: The Range Migration Algorithm (RMA) is an efficient approach to process strip map data with large range cell migration. However, it is sensitive to cross track motion of the radar. To provide for a degree of motion tolerance, an applicable approach is to retain only a portion of the full processed image around a central reference point (CRP) where motion compensation is applied. This results in throwing away that part of the image that is potentially defocused with the result that this discarded data area has to be reprocessed with additional CRPs. This results in a processing in-efficiency that can greatly drive up the processing requirements. An efficient algorithm is being developed which alleviates this wasted data processing in-efficiency problem. This new algorithm, called tyhe Thinned RMA, operates by filtering the data to just the area to be processed and then resampling the data at a much lower rate. The RMA then proceeds normally, but now operates on a much reduced cross track data size. This approach can also provide a much greater tolerance to cross track motion. To date the algorithm as been developed and tested on simulated data and recorded phase history data. Processing speed-ups of approximately 4 to 1 are being achieved compared to a full RMA algorithm that retains a small patch about the CRP. Ultimately the algorithm will progress to a two stage version that will provide the optimum in motion tolerance and processing efficiency. @INPROCEEDINGS{KirkWoodsSalzman04:Processing, author = {John C. Kirk and Don Woods and Joe Salzman}, title = {{Efficient Motion-Tolerant Fopen SAR Processing}}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, volume = {1}, pages = {179-182}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {The Range Migration Algorithm (RMA) is an efficient approach to process strip map data with large range cell migration. However, it is sensitive to cross track motion of the radar. To provide for a degree of motion tolerance, an applicable approach is to retain only a portion of the full processed image around a central reference point (CRP) where motion compensation is applied. This results in throwing away that part of the image that is potentially defocused with the result that this discarded data area has to be reprocessed with additional CRPs. This results in a processing in-efficiency that can greatly drive up the processing requirements. An efficient algorithm is being developed which alleviates this wasted data processing in-efficiency problem. This new algorithm, called tyhe Thinned RMA, operates by filtering the data to just the area to be processed and then resampling the data at a much lower rate. The RMA then proceeds normally, but now operates on a much reduced cross track data size. This approach can also provide a much greater tolerance to cross track motion. To date the algorithm as been developed and tested on simulated data and recorded phase history data. Processing speed-ups of approximately 4 to 1 are being achieved compared to a full RMA algorithm that retains a small patch about the CRP. Ultimately the algorithm will progress to a two stage version that will provide the optimum in motion tolerance and processing efficiency.}, keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Motion Compensation, Thinned Range Migration Algorithm, Airborne SAR}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/KirkWoodsSalzman04.pdf} } -
Gerhard Krieger,
Nicolas Gebert,
and Alberto Moreira.
SAR Signal Reconstruction from Non-Uniform Displaced Phase Centre Sampling.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, Bistatic SAR, Bistatic Processing, Dual Receive Antenna.Abstract: The displaced phase centre (DPC) technique will enable a wide swath SAR with high azimuth resolution. In a classic DPC system, the PRF has to be chosen such that the SAR carrier moves just one half of its antenna length between subsequent radar pulses. Any deviation from this PRF will result in a nonuniform sampling of the synthetic aperture. This paper shows that an unambiguous reconstruction of the SAR signal is also possible in case of such a non-optimum PRF. For this, an innovative reconstruction algorithm is derived, which enables a recovery of the unambiguous Doppler spectrum also in case of a non-uniform sampling of the synthetic aperture. This algorithm will also have a great potential for multistatic satellite constellations as well as the dual receive antennas in Radarsat II and TerraSAR-X. @INPROCEEDINGS{KriegerGebertMoreira04:DisplacedPhase, author = {Gerhard Krieger and Nicolas Gebert and Alberto Moreira}, title = {{SAR Signal Reconstruction from Non-Uniform Displaced Phase Centre Sampling}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {The displaced phase centre (DPC) technique will enable a wide swath SAR with high azimuth resolution. In a classic DPC system, the PRF has to be chosen such that the SAR carrier moves just one half of its antenna length between subsequent radar pulses. Any deviation from this PRF will result in a nonuniform sampling of the synthetic aperture. This paper shows that an unambiguous reconstruction of the SAR signal is also possible in case of such a non-optimum PRF. For this, an innovative reconstruction algorithm is derived, which enables a recovery of the unambiguous Doppler spectrum also in case of a non-uniform sampling of the synthetic aperture. This algorithm will also have a great potential for multistatic satellite constellations as well as the dual receive antennas in Radarsat II and TerraSAR-X.}, keywords = {SAR Processing, Bistatic SAR, Bistatic Processing, Dual Receive Antenna}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/KriegerGebertMoreira04.pdf} } -
J. Li and P. Stoica.
Versatile robust Capon beamforming: theory and applications.
In Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004,
pages 38-42,
July 2004.
Keywords: SAR Processing, SAR Tomography, Tomography, Capon, Robust Capon Beamforming, RCB, acoustic imaging, array signal processing, beam steering, channel bank filters, covariance matrices, ground penetrating radar, image resolution, interference (signal), landmine detection, radar imaging CBRCB, CPRCB, DCRCB, FLGPR imaging system, RCF, SCB, acoustic imaging, constant-beamwidth RCB, constant-powerwidth RCB, covariance fitting formulation, doubly constrained robust Capon beamformer, forward-looking ground penetrating radar, interference rejection, landmine detection, rank-deficient robust Capon filter-bank approach, resolution, spectral estimation, standard Capon beamformer, steering vector.Abstract: The standard Capon beamformer (SCB) has better resolution and much better interference rejection capability than the data-independent beamformer provided that the array steering vector corresponding to the signal-of-interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice), the performance of the Capon beamformer may become worse than that of the data-independent beamformer. Most of the early suggested robust adaptive methods are rather ad hoc in that the choice of their parameters are not directly related to the uncertainly of the steering vector. In this paper we provide a review of the recently proposed robust Capon beam-former (RCB) and doubly constrained robust Capon beamformer (DCRCB), which directly address the uncertainty of the steering vector and naturally extend the covariance fitting formulation of SCB to the case of uncertain steering vectors by enforcing a double constraint on the steering vector, viz. a constant norm constraint and an uncertainty set constraint. We also present several extensions and applications of RCB including constant-powerwidth RCB (CPRCB) and constant-beamwidth RCB (CBRCB) for acoustic imaging, rank-deficient robust Capon filter-bank (RCF) approach for spectral estimation, and rank-deficient RCB for landmine detection using forward-looking ground penetrating radar (FLGPR) imaging systems. The excellent performances of RCB, DCRCB, and the various extensions of RCB are demonstrated by simulated and experimental examples. @INPROCEEDINGS{liStoica2004:RobustCapon, author = {Li, J. and Stoica, P.}, title = {Versatile robust Capon beamforming: theory and applications}, booktitle = {Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004}, year = {2004}, pages = { 38-42}, month = {jul}, abstract = {The standard Capon beamformer (SCB) has better resolution and much better interference rejection capability than the data-independent beamformer provided that the array steering vector corresponding to the signal-of-interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice), the performance of the Capon beamformer may become worse than that of the data-independent beamformer. Most of the early suggested robust adaptive methods are rather ad hoc in that the choice of their parameters are not directly related to the uncertainly of the steering vector. In this paper we provide a review of the recently proposed robust Capon beam-former (RCB) and doubly constrained robust Capon beamformer (DCRCB), which directly address the uncertainty of the steering vector and naturally extend the covariance fitting formulation of SCB to the case of uncertain steering vectors by enforcing a double constraint on the steering vector, viz. a constant norm constraint and an uncertainty set constraint. We also present several extensions and applications of RCB including constant-powerwidth RCB (CPRCB) and constant-beamwidth RCB (CBRCB) for acoustic imaging, rank-deficient robust Capon filter-bank (RCF) approach for spectral estimation, and rank-deficient RCB for landmine detection using forward-looking ground penetrating radar (FLGPR) imaging systems. The excellent performances of RCB, DCRCB, and the various extensions of RCB are demonstrated by simulated and experimental examples.}, doi = {10.1109/SAM.2004.1502905}, issn = { }, keywords = {SAR Processing, SAR Tomography, Tomography, Capon, Robust Capon Beamforming, RCB, acoustic imaging, array signal processing, beam steering, channel bank filters, covariance matrices, ground penetrating radar, image resolution, interference (signal), landmine detection, radar imaging CBRCB, CPRCB, DCRCB, FLGPR imaging system, RCF, SCB, acoustic imaging, constant-beamwidth RCB, constant-powerwidth RCB, covariance fitting formulation, doubly constrained robust Capon beamformer, forward-looking ground penetrating radar, interference rejection, landmine detection, rank-deficient robust Capon filter-bank approach, resolution, spectral estimation, standard Capon beamformer, steering vector}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/liStoica2004.pdf}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1502905} } -
M. Limbach,
B. Gabler,
and Ralf Horn.
Fine Resolution, fully Polarimetric P-band subsystem for E-SAR -- Technique and Results.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
pages 275-278,
2004.
Keywords: SAR Processing, ESAR, P-Band, Airborne SAR, Polarimetry, Polarimetric P-Band.Abstract: The design of the P-band subsystem of DLR's E-SAR system is presented in this paper. With a new microstrip patch antenna and other key hardware components a bandwidth of more than 28 0x1.57b4cffcd5138p-895t a lower centre frequency is achieved. The system parameters correspond to a range resolution better than 2.1m. Measurements of system gain, cross polarisation suppression, system sensitivity and some antenna parameters are shown. @INPROCEEDINGS{limbachGablerHorn04:ESARPBand, author = {M. Limbach and B. Gabler and Ralf Horn}, title = {Fine Resolution, fully Polarimetric P-band subsystem for E-SAR -- Technique and Results}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {275-278}, abstract = {The design of the P-band subsystem of DLR's E-SAR system is presented in this paper. With a new microstrip patch antenna and other key hardware components a bandwidth of more than 28 0x1.57b4cffcd5138p-895t a lower centre frequency is achieved. The system parameters correspond to a range resolution better than 2.1m. Measurements of system gain, cross polarisation suppression, system sensitivity and some antenna parameters are shown.}, keywords = {SAR Processing, ESAR, P-Band, Airborne SAR, Polarimetry,Polarimetric P-Band}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/limbachGablerHorn04.pdf} } -
F. Lombardini,
Joachim H. G. Ender,
L. Rössing,
M. Galletto,
and L. Verrazzani.
Experiments of interferometric layover solution with the three-antenna airborne AER-II SAR system.
In IEEE International Geoscience and Remote Sensing Symposium, IGARSS '04,
volume 5,
pages 3341--3344,
September 2004.
Keywords: SAR Processing, Capon, MUSIC, airborne radar, antenna arrays, radar imaging, radiowave interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, InSAR, SAR imagery, SAR Interferometry, advanced multibaseline operation, airborne experimental radar, calibration, dual-baseline single-pass SAR interferometer, electromagnetic tomography, higher-order interferometry, hybrid spatial spectral estimation, interferometric layover solution, layover-free interferometry, multichannel operation, nonparametric spectral estimation, parametric spectral estimation, spectral analysis, synthetic aperture radar, three-antenna airborne AER-II SAR System, three-antenna nonuniform array data.Abstract: Interest is recently growing in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional SAR and InSAR imagery. In this work we report about: experiments of the functionality of "layover-free" or "higher-order" interferometry with the dual-baseline single-pass SAR interferometer AER-II. Non-parametric, parametric and hybrid spatial spectral estimators are applied to process the three-antenna non uniform array data. Calibration issues, first real data results and impact of order selection are discussed for a bridge over the valley scene @INPROCEEDINGS{lombardiniEnderRoessingGallettoVerrazzani2004:AERLayoverSolution, author = {Lombardini, F. and Ender, Joachim H. G. and R{\"o}ssing, L. and Galletto, M. and Verrazzani, L.}, title = {Experiments of interferometric layover solution with the three-antenna airborne {AER-II} {SAR} system}, booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS '04}, year = {2004}, volume = {5}, pages = {3341--3344}, month = sep, abstract = {Interest is recently growing in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional SAR and InSAR imagery. In this work we report about: experiments of the functionality of "layover-free" or "higher-order" interferometry with the dual-baseline single-pass SAR interferometer AER-II. Non-parametric, parametric and hybrid spatial spectral estimators are applied to process the three-antenna non uniform array data. Calibration issues, first real data results and impact of order selection are discussed for a bridge over the valley scene}, doi = {10.1109/IGARSS.2004.1370419}, keywords = {SAR Processing, Capon, MUSIC, airborne radar, antenna arrays, radar imaging, radiowave interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, InSAR, SAR imagery, SAR Interferometry, advanced multibaseline operation, airborne experimental radar, calibration, dual-baseline single-pass SAR interferometer, electromagnetic tomography, higher-order interferometry, hybrid spatial spectral estimation, interferometric layover solution, layover-free interferometry, multichannel operation, nonparametric spectral estimation, parametric spectral estimation, spectral analysis, synthetic aperture radar, three-antenna airborne AER-II SAR System, three-antenna nonuniform array data}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/lombardiniEnderRoessingGallettoVerrazzani2004.pdf}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01370419} } -
José Márquez-Martìnez and Josef Mittermayer.
Analysis of Range Ambiguity Suppression methods in SAR by using a Novel Range Ambiguity Raw Data Simulator.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
volume 1,
Ulm, Germany,
pages 593-596,
May 25-27 2004.
Keywords: SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Range Ambiguity Suppression, ESAR, Airborne SAR.Abstract: This paper presents a novel range ambiguity raw data simulator (RAS). The simulator was used to investigate range ambiguity suppression obtained by means of up and down chirp coding for point targets and realistic scenes including extended targets. A pre-processing technique for up and down-chirp processing has also been developed. Different applications are investigated using data from the experimental SAR system from DLR (ESAR), either oriented to point target detection or to extended target analysis. Several image processing results with different range ambiguities ratios are presented. @INPROCEEDINGS{MarquezMittermayer04:Simulator, author = {Jos{\'e} M{\'a}rquez-Mart{\'i}nez and Josef Mittermayer}, title = {{Analysis of Range Ambiguity Suppression methods in SAR by using a Novel Range Ambiguity Raw Data Simulator}}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, volume = {1}, pages = {593-596}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {This paper presents a novel range ambiguity raw data simulator (RAS). The simulator was used to investigate range ambiguity suppression obtained by means of up and down chirp coding for point targets and realistic scenes including extended targets. A pre-processing technique for up and down-chirp processing has also been developed. Different applications are investigated using data from the experimental SAR system from DLR (ESAR), either oriented to point target detection or to extended target analysis. Several image processing results with different range ambiguities ratios are presented.}, keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Range Ambiguity Suppression, ESAR, Airborne SAR}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/MarquezMittermayer04.pdf} } -
Yibo Na,
Hongbo Sun,
Yee Hui Lee,
Ling Chiat Tai,
and Hian Lim Chan.
Performance evaluation of back-projection and range migration algorithms in foliage penetration radar imaging.
In Image Processing, 2004. ICIP '04. 2004 International Conference on,
volume 1,
pages 21--24,
2004.
Keywords: SAR Processing, Backprojection, omega-k, Comimage reconstruction, radar imaging, synthetic aperture radar, FOPEN SAR imaging, back-projection algorithm, computer-aided tomography, foliage penetration radar imaging, image reconstruction, range migration algorithm, seismic migration techniques, synthetic aperture radar.Abstract: In this paper, two relatively novel synthetic aperture radar (SAR) imaging techniques, namely the back-projection algorithm and range migration algorithm, are discussed. The back-projection algorithm originates from the medical imaging reconstruction technique called computer-aided tomography whereas the range migration algorithm is derived from seismic migration techniques. In this paper, both the back-projection and range migration algorithms are applied to foliage penetration (FOPEN) SAR imaging and performance comparisons are made. The simulations and experimental data processing results show that both algorithms are suitable for FOPEN radar imaging and that theoretical performances can be achieved. @INPROCEEDINGS{naSunLeeTaiChan04:Backp, author = {Na, Yibo and Sun, Hongbo and Lee, Yee Hui and Tai, Ling Chiat and Chan, Hian Lim}, title = {Performance evaluation of back-projection and range migration algorithms in foliage penetration radar imaging}, booktitle = {Image Processing, 2004. ICIP '04. 2004 International Conference on}, year = {2004}, volume = {1}, pages = {21--24}, abstract = {In this paper, two relatively novel synthetic aperture radar (SAR) imaging techniques, namely the back-projection algorithm and range migration algorithm, are discussed. The back-projection algorithm originates from the medical imaging reconstruction technique called computer-aided tomography whereas the range migration algorithm is derived from seismic migration techniques. In this paper, both the back-projection and range migration algorithms are applied to foliage penetration (FOPEN) SAR imaging and performance comparisons are made. The simulations and experimental data processing results show that both algorithms are suitable for FOPEN radar imaging and that theoretical performances can be achieved.}, issn = {1522-4880}, keywords = {SAR Processing, Backprojection, omega-k, Comimage reconstruction, radar imaging, synthetic aperture radar, FOPEN SAR imaging, back-projection algorithm, computer-aided tomography, foliage penetration radar imaging, image reconstruction, range migration algorithm, seismic migration techniques, synthetic aperture radar}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/naSunLeeTaiChan04.pdf}, url = {http://ieeexplore.ieee.org/iel5/9716/30672/01418679.pdf} } -
Lam H. Nguyen,
Marc Ressler,
and Mehrdad Soumekh.
Signal Processing and Image Formation Using Low-Frequency Ultra-Wideband Radar Data.
In Russell S. Harmon,
J. Thomas Broach,
and John H. Holloway(Jr.), editors,
Proceedings of SPIE: Detection and Remediation Technologies for Mines and Minelike Targets IX,
volume SPIE # 5415,
pages 1053-1064,
2004.
Keywords: SAR Processing, Ultra-Wideband SAR, Backprojection, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Image Formation, RFI Suppression, Digital Spotlighting.Abstract: In support of the U.S. Army Night Vision And Electronic Sensors Directorate (NVESD), the U.S. Army Research Laboratory (ARL) has developed infrastructures, tools, and algorithms to evaluate the data set. This paper focuses on the signal processing and image formation using data from a low-frequency ultrawideband sensor. We examine various issues that are associated with this class of SAR databases such as radio frequency interference (RFI), the effects of spectral notches, and errors in motion measurement to image quality. We show the pre-processing steps such as frequency and phase calibration, radio frequency interference extraction. We also show the application of digital spotlight technique to correct motion errors introduced by the measurement system. Finally, we show the resulting SAR imagery of various minefields. @INPROCEEDINGS{NguyenResslerSoumekh04:LowFreqUWB, author = {Lam H. Nguyen and Marc Ressler and Mehrdad Soumekh}, title = {{Signal Processing and Image Formation Using Low-Frequency Ultra-Wideband Radar Data}}, booktitle = {Proceedings of SPIE: Detection and Remediation Technologies for Mines and Minelike Targets IX}, year = {2004}, editor = {Russell S. Harmon and J. Thomas Broach and John H. Holloway(Jr.)}, volume = SPIE # {5415}, pages = {1053-1064}, abstract = {In support of the U.S. Army Night Vision And Electronic Sensors Directorate (NVESD), the U.S. Army Research Laboratory (ARL) has developed infrastructures, tools, and algorithms to evaluate the data set. This paper focuses on the signal processing and image formation using data from a low-frequency ultrawideband sensor. We examine various issues that are associated with this class of SAR databases such as radio frequency interference (RFI), the effects of spectral notches, and errors in motion measurement to image quality. We show the pre-processing steps such as frequency and phase calibration, radio frequency interference extraction. We also show the application of digital spotlight technique to correct motion errors introduced by the measurement system. Finally, we show the resulting SAR imagery of various minefields.}, keywords = {SAR Processing, Ultra-Wideband SAR, Backprojection, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Image Formation, RFI Suppression, Digital Spotlighting}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/NguyenResslerSoumekh04.pdf}, url = {http://spiedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PSISDG005415000001001053000001&idtype=cvips&gifs=yes} } -
Lam H. Nguyen,
Marc Ressler,
D. Wong,
and Mehrdad Soumekh.
Enhancement of backprojection SAR imagery using digital spotlighting preprocessing.
In Radar Conference, 2004. Proceedings of the IEEE,
pages 53--58,
2004.
Keywords: SAR Processing, Backprojection, Time-Domain Backprojection, Digital Spotlighting, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression, Doppler effect, antialiasing, image enhancement, radar imaging, synthetic aperture radar, ARL boom-SAR data, Doppler aliasing suppression, PRF, SAR data filtering scheme, SAR imagery enhancement, azimuth-compressed SAR data, backprojection SAR imagery, digital spotlighting preprocessing, image fidelity improvement, radar radiation pattern, side lobe artifacts.Abstract: This paper examines signal processing methods for improving the fidelity of backprojection SAR imagery using a preprocessing method that suppresses Doppler aliasing as well as other side lobe artifacts that are introduced by the radar radiation pattern. The algorithm, known as digital spotlighting, imposes a filtering scheme on the azimuth-compressed SAR data, and manipulates the resultant spectral data to achieve a higher PRF to suppress the Doppler aliasing. The merits of the algorithm are studied using the ARL boom-SAR data. @INPROCEEDINGS{nguyenResslerWongSoumekh04:Backproj, author = {Nguyen, Lam H. and Ressler, Marc and Wong, D. and Mehrdad Soumekh}, title = {Enhancement of backprojection SAR imagery using digital spotlighting preprocessing}, booktitle = {Radar Conference, 2004. Proceedings of the IEEE}, year = {2004}, pages = {53--58}, abstract = {This paper examines signal processing methods for improving the fidelity of backprojection SAR imagery using a preprocessing method that suppresses Doppler aliasing as well as other side lobe artifacts that are introduced by the radar radiation pattern. The algorithm, known as digital spotlighting, imposes a filtering scheme on the azimuth-compressed SAR data, and manipulates the resultant spectral data to achieve a higher PRF to suppress the Doppler aliasing. The merits of the algorithm are studied using the ARL boom-SAR data.}, keywords = {SAR Processing,Backprojection,Time-Domain Backprojection,Digital Spotlighting, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression, Doppler effect, antialiasing, image enhancement, radar imaging, synthetic aperture radar, ARL boom-SAR data, Doppler aliasing suppression, PRF, SAR data filtering scheme, SAR imagery enhancement, azimuth-compressed SAR data, backprojection SAR imagery, digital spotlighting preprocessing, image fidelity improvement, radar radiation pattern, side lobe artifacts}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/nguyenResslerWongSoumekh04.pdf}, url = {http://ieeexplore.ieee.org/iel5/9199/29174/01316395.pdf} } -
Lam H. Nguyen,
Tuan Ton,
David Wong,
and Mehrdad Soumekh.
Adaptive coherent suppression of multiple wide-bandwidth RFI sources in SAR.
In Edmund G. Zelnio and Frederick D. Garber, editors,
Algorithms for Synthetic Aperture Radar Imagery XI,
volume 5427,
pages 1-16,
2004.
SPIE.
Keywords: SAR Processing, RFI Suppression, Ultra-Wideband SAR, Wide-Bandwidth RFI, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression.Abstract: This paper is concerned with suppressing multiple wide-bandwidth radio frequency interference (RFI) sources in SAR systems. A coherent processing of passive radar (sniff) data is presented to diminish the effects of wide-bandwidth as well as narrow-bandwidth RFI sources in the active radar data that are collected by a SAR system. The approach is based on a two-dimensional adaptive filtering of the active SAR data using the passive sniff data as the reference signal. A similar mathematical (signal) model and processing is also utilized to suppress self-induced resonance (SIR) signals that are generated by the interaction of the radar-carrying platform and the transmitted radar signal. Results are shown using the Army Research Laboratory (ARL) low-frequency, ultra-wideband (UWB) imaging radar (Boom-SAR). @INPROCEEDINGS{nguyenTonWongSoumekh04:RFI, author = {Lam H. Nguyen and Tuan Ton and David Wong and Mehrdad Soumekh}, title = {Adaptive coherent suppression of multiple wide-bandwidth RFI sources in SAR}, booktitle = {Algorithms for Synthetic Aperture Radar Imagery XI}, year = {2004}, editor = {Edmund G. Zelnio and Frederick D. Garber}, volume = {5427}, number = {1}, pages = {1-16}, publisher = {SPIE}, abstract = {This paper is concerned with suppressing multiple wide-bandwidth radio frequency interference (RFI) sources in SAR systems. A coherent processing of passive radar (sniff) data is presented to diminish the effects of wide-bandwidth as well as narrow-bandwidth RFI sources in the active radar data that are collected by a SAR system. The approach is based on a two-dimensional adaptive filtering of the active SAR data using the passive sniff data as the reference signal. A similar mathematical (signal) model and processing is also utilized to suppress self-induced resonance (SIR) signals that are generated by the interaction of the radar-carrying platform and the transmitted radar signal. Results are shown using the Army Research Laboratory (ARL) low-frequency, ultra-wideband (UWB) imaging radar (Boom-SAR).}, keywords = {SAR Processing, RFI Suppression, Ultra-Wideband SAR,Wide-Bandwidth RFI, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/nguyenTonWongSoumekh04.pdf}, url = {http://link.aip.org/link/?PSI/5427/1/1} } -
David Small,
Michael Jehle,
Erich Meier,
and Daniel Nüesch.
Radiometric Terrain Correction Incorporating Local Antenna Gain.
In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar,
Ulm, Germany,
pages 929-932,
May 25-27 2004.
Keywords: SAR Geocoding, Radiometric Correction, Radiometric Terrain Correction, Radiometric Calibration, Calibration, Local Antenna Gain.Abstract: Radiometric terrain correction consists of normalising a SAR image for well-understood backscatter contributions in order to amplify less easily apparent influences (e.g. thematic land cover variance). A rigorous modelling of the SAR image formation process includes consideration of how foreshortening and layover create ambi guity when connecting map geometry grid points to and from counterparts in radar geometry (slant or ground range vs. azimuth). A radar amplitude image simulation is formed by iterating through a facetted DEM, calcu lating the accumulated illuminated area at every range and azimuth coordinate in radar geometry. We show how DEM-based image simulations gain further realism by incorporating knowledge of the SAR antenna's elevation an-tenna gain pattern (AGP). Although typical AGP corrections assume an ellipsoidal Earth, the AGP is actually draped upon the Earth's terrain. We quantify differences between estimates of local antenna gain and illuminated area performed using (a) the typical ellipsoid assumption, (b) a DEM. We demonstrate application of local antenna gain knowledge within the image simulation process using ENVISAT ASAR images acquired over Switzerland. We introduce a weighted resolution approach for robust combination of multiple radiometrically normalised terrain geocoded backscatter maps. @INPROCEEDINGS{smallJehleMeierNueesch04:TerrainCorr, author = {David Small and Michael Jehle and Erich Meier and Daniel N{\"u}esch}, title = {{Radiometric Terrain Correction Incorporating Local Antenna Gain}}, booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar}, year = {2004}, pages = {929-932}, address = {Ulm, Germany}, month = {May 25-27}, abstract = {Radiometric terrain correction consists of normalising a SAR image for well-understood backscatter contributions in order to amplify less easily apparent influences (e.g. thematic land cover variance). A rigorous modelling of the SAR image formation process includes consideration of how foreshortening and layover create ambi guity when connecting map geometry grid points to and from counterparts in radar geometry (slant or ground range vs. azimuth). A radar amplitude image simulation is formed by iterating through a facetted DEM, calcu lating the accumulated illuminated area at every range and azimuth coordinate in radar geometry. We show how DEM-based image simulations gain further realism by incorporating knowledge of the SAR antenna's elevation an-tenna gain pattern (AGP). Although typical AGP corrections assume an ellipsoidal Earth, the AGP is actually draped upon the Earth's terrain. We quantify differences between estimates of local antenna gain and illuminated area performed using (a) the typical ellipsoid assumption, (b) a DEM. We demonstrate application of local antenna gain knowledge within the image simulation process using ENVISAT ASAR images acquired over Switzerland. We introduce a weighted resolution approach for robust combination of multiple radiometrically normalised terrain geocoded backscatter maps.}, keywords = {SAR Geocoding,Radiometric Correction, Radiometric Terrain Correction,Radiometric Calibration,Calibration,Local Antenna Gain}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/smallJehleMeierNueesch04.pdf} } -
David Small,
Erich Meier,
and Daniel Nüesch.
Robust radiometric terrain correction for SAR image comparisons.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
volume 3,
pages 1730--1733,
2004.
Keywords: backscatter, radiometry, remote sensing by radar, terrain mapping, AGP, ENVISAT ASAR images, Earth ellipsoid, Earth rolling terrain, SAR imagery, Switzerland, composite radar map, ideal flat terrain, local antenna gain pattern, mountainous terrain, normalized images, radar backscatter coefficient, radar brightness coefficient, radar equation, radiometric errors, radiometrically calibrated images, robust radar image simulation, robust radiometric terrain correction, robust technique, terrain geocoded images, terrain induced modulations, terrain variations.Abstract: We demonstrate a robust technique for radiometric terrain correction, whereby terrain-induced modulations of the radiometry of SAR imagery are modelled and corrected. The resulting normalized images may be more easily compared with other data sets acquired at different incidence angles, even opposing look directions. We begin by reviewing the radar equation, pointing out simplifications often made to reduce the complexity of calculating the backscatter coefficient, normalized either by ground area (/spl sigma//sup 0/), or illuminated area projected into the look direction (/spl gamma//sup 0/). The integral over the illuminated area is often approximated by a scale factor modelling a simple planar slope, departing only slightly from "ideal" flat terrain: for /spl gamma//sup 0/, the radar brightness (/spl beta//sup 0/) is normalized via modulation with the tangent of the local incidence angle. We quantify the radiometric errors introduced by ignoring terrain variations, comparing results based on (a) a robust radar image simulation-based approach properly modelling variations in local illuminated area, and (b) an ellipsoidal Earth assumption. A second simplification often made in solving for backscatter using the radar equation is the assumption that the local antenna gain does not vary significantly from a simple model draping the antenna gain pattern (AGP) across an Earth ellipsoid, returning the local antenna gain as a function of slant range alone. In reality, the AGP is draped across the Earth's rolling terrain retrieval of properly calibrated backscatter values should model these variations and compensate for them: although smaller than the errors caused by not property modelling variations in local illuminated area, they can be significant. We use well-calibrated and annotated ENVISAT ASAR images acquired over Switzerland to show how robust radiometric terrain correction, incorporating models for the variations of local illuminated area with terrain enables calibrated mixture of imagery acquired at differing incidence angles. Only robust retrieval of backscatter values enables such inter-mode comparisons - a capability that significantly reduces the required revisit time for monitoring changes to the radar backscatter. In conclusion, we describe a techn- ique for combining a set of terrain-geocoded and radiometrically calibrated images derived from ascending and descending passes and multiple incidence angles to create composite radar backscatter maps. At each point, the contribution of each image to the composite is weighted according to its local resolution. The resulting composite image manifests relatively uniform high ground resolution, even in highly mountainous terrain. @INPROCEEDINGS{smallMeierNueesch04:TerrainCorr, author = {Small, David and Meier, Erich and N{\"u}esch, Daniel}, title = {Robust radiometric terrain correction for SAR image comparisons}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, volume = {3}, pages = {1730--1733}, abstract = {We demonstrate a robust technique for radiometric terrain correction, whereby terrain-induced modulations of the radiometry of SAR imagery are modelled and corrected. The resulting normalized images may be more easily compared with other data sets acquired at different incidence angles, even opposing look directions. We begin by reviewing the radar equation, pointing out simplifications often made to reduce the complexity of calculating the backscatter coefficient, normalized either by ground area (/spl sigma//sup 0/), or illuminated area projected into the look direction (/spl gamma//sup 0/). The integral over the illuminated area is often approximated by a scale factor modelling a simple planar slope, departing only slightly from "ideal" flat terrain: for /spl gamma//sup 0/, the radar brightness (/spl beta//sup 0/) is normalized via modulation with the tangent of the local incidence angle. We quantify the radiometric errors introduced by ignoring terrain variations, comparing results based on (a) a robust radar image simulation-based approach properly modelling variations in local illuminated area, and (b) an ellipsoidal Earth assumption. A second simplification often made in solving for backscatter using the radar equation is the assumption that the local antenna gain does not vary significantly from a simple model draping the antenna gain pattern (AGP) across an Earth ellipsoid, returning the local antenna gain as a function of slant range alone. In reality, the AGP is draped across the Earth's rolling terrain retrieval of properly calibrated backscatter values should model these variations and compensate for them: although smaller than the errors caused by not property modelling variations in local illuminated area, they can be significant. We use well-calibrated and annotated ENVISAT ASAR images acquired over Switzerland to show how robust radiometric terrain correction, incorporating models for the variations of local illuminated area with terrain enables calibrated mixture of imagery acquired at differing incidence angles. Only robust retrieval of backscatter values enables such inter-mode comparisons - a capability that significantly reduces the required revisit time for monitoring changes to the radar backscatter. In conclusion, we describe a techn- ique for combining a set of terrain-geocoded and radiometrically calibrated images derived from ascending and descending passes and multiple incidence angles to create composite radar backscatter maps. At each point, the contribution of each image to the composite is weighted according to its local resolution. The resulting composite image manifests relatively uniform high ground resolution, even in highly mountainous terrain.}, journal = {Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International}, keywords = {backscatter, radiometry, remote sensing by radar, terrain mapping, AGP, ENVISAT ASAR images, Earth ellipsoid, Earth rolling terrain, SAR imagery, Switzerland, composite radar map, ideal flat terrain, local antenna gain pattern, mountainous terrain, normalized images, radar backscatter coefficient, radar brightness coefficient, radar equation, radiometric errors, radiometrically calibrated images, robust radar image simulation, robust radiometric terrain correction, robust technique, terrain geocoded images, terrain induced modulations, terrain variations}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/smallMeierNueesch04.pdf}, url = {http://ieeexplore.ieee.org/iel5/9436/29946/01370666.pdf} } -
David Small,
Betlem Rosich,
Erich Meier,
and Daniel Nüesch.
Geometric Calibration and Validation of ASAR Imagery.
In CEOS SAR Workshop 2004,
Ulm,
May 2004.
Keywords: SAR Geocoding, Calibration, Validation, Quality Assessment, ASAR, ENVISAT.Abstract: We describe work conducted to calibrate and then validate the geometry of ENVISAT ASAR products. A systematic error in range location was observed in ASAR products during the commissioning phase. A careful and complete analysis has been performed to establish the precise error. It has been compensated by updating the range gate bias (or sampling window start time bias). Validation of the absolute location accuracy of most ASAR products was performed subsequently. The location of surveyed targets is predicted using the satellite state vectors and ancillary timing information via the range and Doppler equations. The prediction's accuracy is affected by instrument bias, ionospheric and atmospheric path delay, as well as target survey errors. Transponders are in addition subject to internal delay uncertainty. The positions of the strong transponder and corner reflector targets in the images are measured to sub-sample accuracy by employing large oversampling factors. Initial and residual bias determinations were made using image acquisitions covering transponders and corner reflectors in the Netherlands, Canada, and Switzerland. Using a large number of independent targets helps reduce the influence of their independent survey errors. The highest resolution slant range single look complex (SLC) products (IMS, APS) were mainly used for testing. In addition, absolute location error was also measured on selected ground range products (IMP, APP, IMM, APM, WSM). Some ground range products also require treatment of multiple slant/ground range polynomials - proper handling is validated. For all test cases processed with precise orbits to date, the residual bias in the slant range direction has been smaller than the size of a single range sample. Predictability of target image location within ASAR image products is very high - better than experience with ERS-1/2, JERS-1, and RADARSAT-1. This result is encouraging, as it opens possibilities for ground control point (GCP) free terrain-geocoding and simplified interferometric processing. @INPROCEEDINGS{SmallRosichMeierNueesch04:ASARGeoloc, author = {David Small and Betlem Rosich and Erich Meier and Daniel N{\"u}esch}, title = {{Geometric Calibration and Validation of ASAR Imagery}}, booktitle = {CEOS SAR Workshop 2004}, year = {2004}, address = {Ulm}, month = May, abstract = {We describe work conducted to calibrate and then validate the geometry of ENVISAT ASAR products. A systematic error in range location was observed in ASAR products during the commissioning phase. A careful and complete analysis has been performed to establish the precise error. It has been compensated by updating the range gate bias (or sampling window start time bias). Validation of the absolute location accuracy of most ASAR products was performed subsequently. The location of surveyed targets is predicted using the satellite state vectors and ancillary timing information via the range and Doppler equations. The prediction's accuracy is affected by instrument bias, ionospheric and atmospheric path delay, as well as target survey errors. Transponders are in addition subject to internal delay uncertainty. The positions of the strong transponder and corner reflector targets in the images are measured to sub-sample accuracy by employing large oversampling factors. Initial and residual bias determinations were made using image acquisitions covering transponders and corner reflectors in the Netherlands, Canada, and Switzerland. Using a large number of independent targets helps reduce the influence of their independent survey errors. The highest resolution slant range single look complex (SLC) products (IMS, APS) were mainly used for testing. In addition, absolute location error was also measured on selected ground range products (IMP, APP, IMM, APM, WSM). Some ground range products also require treatment of multiple slant/ground range polynomials - proper handling is validated. For all test cases processed with precise orbits to date, the residual bias in the slant range direction has been smaller than the size of a single range sample. Predictability of target image location within ASAR image products is very high - better than experience with ERS-1/2, JERS-1, and RADARSAT-1. This result is encouraging, as it opens possibilities for ground control point (GCP) free terrain-geocoding and simplified interferometric processing.}, day = {27-28}, keywords = {SAR Geocoding, Calibration, Validation, Quality Assessment, ASAR, ENVISAT}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/SmallRosichMeierNueesch04.pdf} } -
David Small,
Betlem Rosich,
Adrian Schubert,
Erich Meier,
and Daniel Nüesch.
Geometric Validation of Low and High-Resolution ASAR Imagery.
In Proc. of the 2004 Envisat & ERS Symposium,
ESA SP-572,
Salzburg,
Sep. 2004.
Keywords: SAR Processing, SAR Geocoding, Geocoding, Validation, Geometric Validation, ASAR, ENVISAT.@INPROCEEDINGS{smallRosichSchubertMeierNueesch04:SubmittedBistatic, author = {David Small and Betlem Rosich and Adrian Schubert and Erich Meier and Daniel N{\"u}esch}, title = {{Geometric Validation of Low and High-Resolution ASAR Imagery}}, booktitle = {Proc. of the 2004 Envisat \& ERS Symposium}, year = {2004}, series = {ESA SP-572}, address = {Salzburg}, month = {Sep.}, day = {6-10}, keywords = {SAR Processing, SAR Geocoding,Geocoding, Validation, Geometric Validation, ASAR, ENVISAT}, owner = {ofrey} } -
Junfeng Wang and Xingzhao Liu.
SAR Automatic Range-Migration Correction.
In IGARSS '04, International Geoscience and Remote Sensing Symposium,
Sept 2004.
Keywords: SAR Processing, range-Doppler Algorithm, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Migration Correction.Abstract: A new idea is presented to correct range migration in SAR imaging. In the range-Doppler domain, all the samples at a given Doppler frequency constitute a Doppler slice. Different Doppler slices are found to have similar envelopes. According to this similarity, the Doppler slices are shifted in range to correct range migration. This technique applies even without the prior information about the relative motion between the radar and the target. @INPROCEEDINGS{WangLiu04:RangeMigration, author = {Junfeng Wang and Xingzhao Liu}, title = {{SAR Automatic Range-Migration Correction}}, booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium}, year = {2004}, month = Sept, abstract = {A new idea is presented to correct range migration in SAR imaging. In the range-Doppler domain, all the samples at a given Doppler frequency constitute a Doppler slice. Different Doppler slices are found to have similar envelopes. According to this similarity, the Doppler slices are shifted in range to correct range migration. This technique applies even without the prior information about the relative motion between the radar and the target.}, keywords = {SAR Processing, range-Doppler Algorithm, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Migration Correction}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/WangLiu04.pdf} }
Internal reports
-
Betlem Rosich and Peter Meadows.
Absolute Calibration of ASAR Level 1 Products Generated with PF-ASAR.
Technical report Iss. 1 rev. 5,
ESA,
Oct. 2004.
Keywords: ASAR, ENVISAT, Calibration, Validation, Product Calibration, Quality Measures, Quality Assessment, Level 1 Products, SAR.Abstract: The aim of this document is to describe the absolute calibration of high rate ASAR Level 1 products generated by ESA using the ASAR processing Facility (PF-ASAR). ESA ASAR level 1 products are generated at the Processing and Archiving Centres (PACs) and at the acquisitions stations: D-PAC, I-PAC, UK-PAC, PDHS-K (Kiruna), PDHS-E (Esrin). Since the same processor is used in all facilities, a unique methodology is described here, which is applicable to any product regardless of where it has been generated. The document is organised as follows: Section 3 describes the derivation of sigma and gamma nought over distributed targets. Section 4 presents the estimation of point targets Radar Cross Section. Annex A provides a procedure to derive the elevation angle for each image pixel, which is a key parameter for the absolute product calibration. Annex B describes how to perform the elevation antenna pattern correction, which is required for complex products calibration. Annex C defines the parameters required for the above operations. Annex D is provided for reference. It presents the evolution of the elevation antenna pattern since Aug. 2002. Comments: Reference: ENVI-CLVL-EOPG-TN-03-0010, Issue 1, revision 5, 07. Oct 2004 @TECHREPORT{RosichMeadows04:ASAR, author = {Betlem Rosich and Peter Meadows}, title = {{Absolute Calibration of ASAR Level 1 Products Generated with PF-ASAR}}, institution = {ESA}, year = {2004}, number = {Iss. 1 rev. 5}, month = {Oct.}, abstract = {The aim of this document is to describe the absolute calibration of high rate ASAR Level 1 products generated by ESA using the ASAR processing Facility (PF-ASAR). ESA ASAR level 1 products are generated at the Processing and Archiving Centres (PACs) and at the acquisitions stations: D-PAC, I-PAC, UK-PAC, PDHS-K (Kiruna), PDHS-E (Esrin). Since the same processor is used in all facilities, a unique methodology is described here, which is applicable to any product regardless of where it has been generated. The document is organised as follows: Section 3 describes the derivation of sigma and gamma nought over distributed targets. Section 4 presents the estimation of point targets Radar Cross Section. Annex A provides a procedure to derive the elevation angle for each image pixel, which is a key parameter for the absolute product calibration. Annex B describes how to perform the elevation antenna pattern correction, which is required for complex products calibration. Annex C defines the parameters required for the above operations. Annex D is provided for reference. It presents the evolution of the elevation antenna pattern since Aug. 2002.}, comments = {Reference: ENVI-CLVL-EOPG-TN-03-0010, Issue 1, revision 5, 07. Oct 2004}, day = {7}, keywords = {ASAR, ENVISAT, Calibration, Validation, Product Calibration, Quality Measures, Quality Assessment,Level 1 Products, SAR}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/ASARproductsabsolutecalibrationv1.5.pdf} }
Miscellaneous
-
Daniel Svensson and Jan Johansson.
Suppression of Radio Frequency Interference in Low Frequency SAR.
Master's thesis,
Chalmers University of Technology,
2004.
Keywords: SAR Processing, RFI Suppression, CARABAS, Airborne SAR, Analogue TV, VHF SAR.Abstract: To acquire high resolution in airborne radar imaging, either minuscule wavelengths or incredibly large antennas must be used. Another way of solving that issue is to utilise moving radar to realise the effect of a large aperture; a technique called synthetic aperture radar (SAR). CARABAS is a low frequency SAR system, operating in the band of 20 ? 90 MHz, designed to minimise the influence from speckle by using wavelengths of the same order as the resolution cells of the ground image. Radio frequency interference (RFI) is, however, highly prevalent in that frequency band, and must be filtered before the SAR image formation is initialised. The purpose of this thesis is to investigate a proposed method of suppressing RFI, particularly from analogue TV, with a technique based on Doppler compression filtering, to conclude if that technique is applicable. The technique is based on the fact that temporal variations in the TV signal can be predicted. Thus, by synchronising the radar transmission to the line synchronisation pulse of the TV signal, the interference after pulse compression will be concentrated to a component at DC and components at the field rate and its harmonics, in the slow time unfolding of radar data, which enables efficient notch filtering in the range and Doppler domains. The thesis has been carried out at Ericsson Microwave Systems AB in M?lndal, under the supervision of Dr. Hans Hellsten, the originator of CARABAS. The thesis work comprised thorough literature studies, profound measurements of DVD signals, representing ordinary TV signals, implementation of the proposed RFI suppression system in MATLAB, and analysis of the system, regarding attained suppression for different parameter sets. From the results of the thesis it can be concluded that the suppression technique is indeed applicable, but that not all parameter sets provide the required mitigation of 30 dB. That requirement was only fulfilled for two cases: for one second of integration time, together with 4 Hz null-to-null notch widths, and for two seconds of integration time, together with 2 Hz notch widths ? both with a PRF of 15 kHz and a complete Doppler band-pass filtering outside the interval of ?100 to 100 Hz. @MASTERSTHESIS{svenssonJohansson04:RFI, author = {Daniel Svensson and Jan Johansson}, title = {Suppression of Radio Frequency Interference in Low Frequency SAR}, school = {Chalmers University of Technology}, year = {2004}, abstract = {To acquire high resolution in airborne radar imaging, either minuscule wavelengths or incredibly large antennas must be used. Another way of solving that issue is to utilise moving radar to realise the effect of a large aperture; a technique called synthetic aperture radar (SAR). CARABAS is a low frequency SAR system, operating in the band of 20 ? 90 MHz, designed to minimise the influence from speckle by using wavelengths of the same order as the resolution cells of the ground image. Radio frequency interference (RFI) is, however, highly prevalent in that frequency band, and must be filtered before the SAR image formation is initialised. The purpose of this thesis is to investigate a proposed method of suppressing RFI, particularly from analogue TV, with a technique based on Doppler compression filtering, to conclude if that technique is applicable. The technique is based on the fact that temporal variations in the TV signal can be predicted. Thus, by synchronising the radar transmission to the line synchronisation pulse of the TV signal, the interference after pulse compression will be concentrated to a component at DC and components at the field rate and its harmonics, in the slow time unfolding of radar data, which enables efficient notch filtering in the range and Doppler domains. The thesis has been carried out at Ericsson Microwave Systems AB in M?lndal, under the supervision of Dr. Hans Hellsten, the originator of CARABAS. The thesis work comprised thorough literature studies, profound measurements of DVD signals, representing ordinary TV signals, implementation of the proposed RFI suppression system in MATLAB, and analysis of the system, regarding attained suppression for different parameter sets. From the results of the thesis it can be concluded that the suppression technique is indeed applicable, but that not all parameter sets provide the required mitigation of 30 dB. That requirement was only fulfilled for two cases: for one second of integration time, together with 4 Hz null-to-null notch widths, and for two seconds of integration time, together with 2 Hz notch widths ? both with a PRF of 15 kHz and a complete Doppler band-pass filtering outside the interval of ?100 to 100 Hz.}, keywords = {SAR Processing, RFI Suppression, CARABAS, Airborne SAR, Analogue TV, VHF SAR}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/svenssonJohansson04.pdf} }
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This collection of SAR literature is far from being complete.
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Last modified: Wed Sep 8 19:32:46 2010
Author: Othmar Frey , Remote Sensing Laboratories (RSL), University of Zurich, Switzerland .
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