BACK TO INDEX


Publications of year 1998

Articles in journal or book chapters

  1. Richard Bamler and Philipp Hartl. Synthetic Aperture Radar Interferometry. Inverse Problems, 14:1-54, August 1998.
    Keywords: SAR Processing, Interferometry.
    Abstract: Synthetic aperture radar (SAR) is a coherent active microwave imaging method. In remote sensing it is used for mapping the scattering properties of the Earth's surface in the respective wavelength domain. Many physical and geometric parameters of the imaged scene contribute to the grey value of a SAR image pixel. Scene inversion suffers from this high ambiguity and requires SAR data taken at different wavelength, polarization, time, incidence angle, etc. Interferometric SAR (InSAR) exploits the phase differences of at least two complex-valued SAR images acquired from different orbit positions and/or at different times. The information derived from these interferometric data sets can be used to measure several geophysical quantities, such as topography, deformations (volcanoes, earthquakes, ice fields), glacier flows, ocean currents, vegetation properties, etc. This paper reviews the technology and the signal theoretical aspects of InSAR. Emphasis is given to mathematical imaging models and the statistical properties of the involved quantities. Coherence is shown to be a useful concept for system description and for interferogram quality assessment. As a key step in InSAR signal processing two-dimensional phase unwrapping is discussed in detail. Several interferometric configurations are described and illustrated by real-world examples. A compilation of past, current and future InSAR systems concludes the paper. 

    @ARTICLE{BamlerHartl98:InSAR,
author = {Richard Bamler and Philipp Hartl},
title = {{Synthetic Aperture Radar Interferometry}},
journal = {Inverse Problems},
year = {1998},
volume = {14},
pages = {1-54},
month = Aug,
abstract = {Synthetic aperture radar (SAR) is a coherent active microwave imaging method. In remote sensing it is used for mapping the scattering properties of the Earth's surface in the respective wavelength domain. Many physical and geometric parameters of the imaged scene contribute to the grey value of a SAR image pixel. Scene inversion suffers from this high ambiguity and requires SAR data taken at different wavelength, polarization, time, incidence angle, etc. Interferometric SAR (InSAR) exploits the phase differences of at least two complex-valued SAR images acquired from different orbit positions and/or at different times. The information derived from these interferometric data sets can be used to measure several geophysical quantities, such as topography, deformations (volcanoes, earthquakes, ice fields), glacier flows, ocean currents, vegetation properties, etc. This paper reviews the technology and the signal theoretical aspects of InSAR. Emphasis is given to mathematical imaging models and the statistical properties of the involved quantities. Coherence is shown to be a useful concept for system description and for interferogram quality assessment. As a key step in InSAR signal processing two-dimensional phase unwrapping is discussed in detail. Several interferometric configurations are described and illustrated by real-world examples. A compilation of past, current and future InSAR systems concludes the paper.},
comment = {++ very complete overview of InSAR},
keywords = {SAR Processing, Interferometry},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/BamlerHartl98.pdf},
url = {http://www.geomatics.ucalgary.ca/~collins/Handouts/inSAR          0xffcd5138apers/Bamler&Hartl.pdf} 
}


  2. Hian Lim Chan and Tat Soon Yeo. Noniterative quality phase-gradient autofocus (QPGA) algorithm for spotlight SAR imagery. Geoscience and Remote Sensing, IEEE Transactions on, 36(5):1531--1539, Sept. 1998.
    Keywords: SAR Processing, Autofocus, Phase Gradient Autofocus.
    Abstract: The phase-gradient autofocus (PGA) technique is robust over a wide range of imagery and phase error functions, but the convergence usually requires four–six iterations. It is necessarily iterative in an attempt to converge on a dominant target against clutter interference, while sufficiently capturing the blur function. In this paper, we propose to speed the estimation convergence by selectively increasing the pool of quality synchronization sources and not be limited by the range pixels of the SAR map. This is highly probable since each range bin contains more than one prominent scatterer across the integration aperture. It is also highly probable that the least-brightest selected scatterer in a range gate may turn out to be of higher energy as compared to the maximum brightest scatterer of another gate. With appropriate target filtering to final select the quality scatterers out of the large pool and with higher order phase error measurement tool, the new algorithm achieves near-convergence focusing quality without iteration. We named this solution the quality PGA (QPGA) algorithm. 

    @ARTICLE{Chan1998,
author = {Hian Lim Chan and Tat Soon Yeo},
title = {Noniterative quality phase-gradient autofocus (QPGA) algorithm for spotlight SAR imagery},
journal = {Geoscience and Remote Sensing, IEEE Transactions on},
year = {1998},
volume = {36},
pages = {1531--1539},
number = {5},
month = {Sept.},
abstract = {The phase-gradient autofocus (PGA) technique is 

robust over a wide range of imagery and phase error functions, 

but the convergence usually requires four–six iterations. It is 

necessarily iterative in an attempt to converge on a dominant 

target against clutter interference, while sufficiently capturing 

the blur function. In this paper, we propose to speed the estimation 

convergence by selectively increasing the pool of quality 

synchronization sources and not be limited by the range pixels 

of the SAR map. This is highly probable since each range bin 

contains more than one prominent scatterer across the integration 

aperture. It is also highly probable that the least-brightest selected 

scatterer in a range gate may turn out to be of higher energy 

as compared to the maximum brightest scatterer of another 

gate. With appropriate target filtering to final select the quality 

scatterers out of the large pool and with higher order phase error 

measurement tool, the new algorithm achieves near-convergence 

focusing quality without iteration. We named this solution the 

quality PGA (QPGA) algorithm.},
keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/chanYeo98.pdf} 
}


  3. Hyeokho Choi and David C. Munson, Jr.. Direct-Fourier Reconstruction in Tomography and Synthetic Aperture Radar. International Journal of Imaging Systems and Technology, 9(1):1--13, 1998.
    Keywords: SAR Processing, Tomography, Computed Tomography, CT, Convolution Backprojection, CBP, Direct-Fourier Image Reconstruction, DF, Interpolator, Fourier-Domain Interpolator.
    Abstract: We investigate the use of direct-Fourier (DF) image reconstruction in computed tomography and synthetic aperture radar (SAR). One of our aims is to determine why the convolution-backprojection (CBP) method is favored over DF methods in tomography, while DF methods are virtually always used in SAR. We show that the CBP algorithm is equivalent to DF reconstruction using a Jacobian-weighted two-dimensional periodic sinc-kernel interpolator. This interpolation is not optimal in any sense, which suggests that DF algorithms using optimal interpolators may surpass CBP in image quality. We consider use of two types of DF interpolation: a windowed sinc kernel, and the least-squares optimal Yen interpolator. Simulations show that reconstructions using the Yen interpolator do not possess the expected visual quality, because of regularization needed to preserve numerical stability. Next, we show that with a concentric-squares sampling scheme, DF interpolation can be performed accurately and efficiently, producing imagery that is superior to that obtainable by other algorithms. In the case of SAR, we show that the DF method performs very well with interpolators of low complexity. We also study DF reconstruction in SAR for trapezoidal grids. We conclude that the success of the DF method in SAR imaging is due to the nearly Cartesian shape of the sampling grid. 

    @ARTICLE{choiMunson98:CTSAR,
author = {Hyeokho Choi and David C. {Munson, Jr.}},
title = {Direct-Fourier Reconstruction in Tomography and Synthetic Aperture Radar},
journal = {International Journal of Imaging Systems and Technology},
year = {1998},
volume = {9},
pages = {1--13},
number = {1},
abstract = {We investigate the use of direct-Fourier (DF) image reconstruction in computed tomography and synthetic aperture radar (SAR). One of our aims is to determine why the convolution-backprojection (CBP) method is favored over DF methods in tomography, while DF methods are virtually always used in SAR. We show that the CBP algorithm is equivalent to DF reconstruction using a Jacobian-weighted two-dimensional periodic sinc-kernel interpolator. This interpolation is not optimal in any sense, which suggests that DF algorithms using optimal interpolators may surpass CBP in image quality. We consider use of two types of DF interpolation: a windowed sinc kernel, and the least-squares optimal Yen interpolator. Simulations show that reconstructions using the Yen interpolator do not possess the expected visual quality, because of regularization needed to preserve numerical stability. Next, we show that with a concentric-squares sampling scheme, DF interpolation can be performed accurately and efficiently, producing imagery that is superior to that obtainable by other algorithms. In the case of SAR, we show that the DF method performs very well with interpolators of low complexity. We also study DF reconstruction in SAR for trapezoidal grids. We conclude that the success of the DF method in SAR imaging is due to the nearly Cartesian shape of the sampling grid.},
keywords = {SAR Processing, Tomography, Computed Tomography, CT, Convolution Backprojection, CBP, Direct-Fourier Image Reconstruction, DF, Interpolator, Fourier-Domain Interpolator},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/choiMunson98.pdf},
url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/37668/PDFSTART} 
}


  4. S.R. Cloude and Konstantinos P. Papathanassiou. Polarimetric SAR interferometry. IEEE Transactions on Geoscience and Remote Sensing, 36(5):1551-1565, September 1998.
    Keywords: SAR Processing, PolInSAR, geophysical techniques, radar imaging, radar polarimetry, radar theory, remote sensing by radar, synthetic aperture radarInSAR, coherence optimization problem, elevated forest canopy, general formulation, geophysical measurement technique, interferogram, interferometric SAR, interferometric coherence, land surface, linear combinations, maximization, polarimetric SAR interferometry, polarimetric basis transformation, radar polarimetry, radar remote sensing, scalar interferometry, stochastic scattering model, strong polarization dependency, synthetic aperture radar, terrain mapping, vector wave interferometry, SAR Tomography.
    Abstract: The authors examine the role of polarimetry in synthetic aperture radar (SAR) interferometry. They first propose a general formulation for vector wave interferometry that includes conventional scalar interferometry as a special case. Then, they show how polarimetric basis transformations can be introduced into SAR interferometry and applied to form interferograms between all possible linear combinations of polarization states. This allows them to reveal the strong polarization dependency of the interferometric coherence. They then solve the coherence optimization problem involving maximization of interferometric coherence and formulate a new coherent decomposition for polarimetric SAR interferometry that allows the separation of the effective phase centers of different scattering mechanisms. A simplified stochastic scattering model for an elevated forest canopy is introduced to demonstrate the effectiveness of the proposed algorithms. In this way, they demonstrate the importance of wave polarization for the physical interpretation of SAR interferograms. They investigate the potential of polarimetric SAR interferometry using results from the evaluation of fully polarimetric interferometric shuttle imaging radar (SIR)-C/X-SAR data collected during October 8-9, 1994, over the SE Baikal Lake Selenga delta region of Buriatia, Southeast Siberia, Russia 

    @ARTICLE{cloudePapathanassiou1998:PolInSAR,
author = {Cloude, S.R. and Papathanassiou, Konstantinos P.},
title = {Polarimetric {SAR} interferometry},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1998},
volume = {36},
pages = {1551-1565},
number = {5},
month = {Sep},
abstract = {The authors examine the role of polarimetry in synthetic aperture radar (SAR) interferometry. They first propose a general formulation for vector wave interferometry that includes conventional scalar interferometry as a special case. Then, they show how polarimetric basis transformations can be introduced into SAR interferometry and applied to form interferograms between all possible linear combinations of polarization states. This allows them to reveal the strong polarization dependency of the interferometric coherence. They then solve the coherence optimization problem involving maximization of interferometric coherence and formulate a new coherent decomposition for polarimetric SAR interferometry that allows the separation of the effective phase centers of different scattering mechanisms. A simplified stochastic scattering model for an elevated forest canopy is introduced to demonstrate the effectiveness of the proposed algorithms. In this way, they demonstrate the importance of wave polarization for the physical interpretation of SAR interferograms. They investigate the potential of polarimetric SAR interferometry using results from the evaluation of fully polarimetric interferometric shuttle imaging radar (SIR)-C/X-SAR data collected during October 8-9, 1994, over the SE Baikal Lake Selenga delta region of Buriatia, Southeast Siberia, Russia},
doi = {10.1109/36.718859},
issn = {0196-2892},
keywords = {SAR Processing, PolInSAR, geophysical techniques, radar imaging, radar polarimetry, radar theory, remote sensing by radar, synthetic aperture radarInSAR, coherence optimization problem, elevated forest canopy, general formulation, geophysical measurement technique, interferogram, interferometric SAR, interferometric coherence, land surface, linear combinations, maximization, polarimetric SAR interferometry, polarimetric basis transformation, radar polarimetry, radar remote sensing, scalar interferometry, stochastic scattering model, strong polarization dependency, synthetic aperture radar, terrain mapping, vector wave interferometry, SAR Tomography},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/cloudePapathanassiou1998.pdf},
url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=718859&isnumber=15531} 
}


  5. Stuart R. DeGraaf. SAR imaging via modern 2-D spectral estimation methods. Image Processing, IEEE Transactions on, 7(5):729--761, 1998.
    Keywords: SAR Processing, Spectral Estimation, adaptive estimation, adaptive signal processing, estimation theory, image resolution, interference suppression, radar imaging, radar interference, radiowave interferometry, speckle, spectral analysis, synthetic aperture radar, 2-D spectral estimation methods, ASR, MVM, RRMVM, SVA, adaptive SAR imaging, adaptive nulling, adaptive sidelobe reduction, adaptive spectral estimation, averaging, height estimates, interferometric height, minimum variance method, multichannel variants, polarimetric displaced-aperture interferometric data, power spectrum estimation methods, reduced-rank MVM, reflectivity intensity, resolution, scattering intensity, sidelobe artifacts, space variant apodization, speckle, synthetic aperture radar imaging, MUSIC.
    Abstract: Discusses the use of modern 2D spectral estimation algorithms forsynthetic aperture radar (SAR) imaging. The motivation for applyingpower spectrum estimation methods to SAR imaging is to improveresolution, remove sidelobe artifacts, and reduce speckle compared towhat is possible with conventional Fourier transform SAR imagingtechniques. This paper makes two principal contributions to the field ofadaptive SAR imaging. First, it is a comprehensive comparison of 2Dspectral estimation methods for SAR imaging. It provides a synopsis ofthe algorithms available, discusses their relative merits for SARimaging, and illustrates their performance on simulated and collectedSAR imagery. Some of the algorithms presented or their derivations arenew, as are some of the insights into or analyses of the algorithms.Second, this work develops multichannel variants of four relatedalgorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM),adaptive sidelobe reduction (ASR) and space variant apodization (SVA) toestimate both reflectivity intensity and interferometric height frompolarimetric displaced-aperture interferometric data. All of theseinterferometric variants are new. In the interferometric contest,adaptive spectral estimation can improve the height estimates through acombination of adaptive nulling and averaging. Examples illustrate thatMVM, ASR, and SVA offer significant advantages over Fourier methods forestimating both scattering intensity and interferometric height, andallow empirical comparison of the accuracies of Fourier, MVM, ASR, andSVA interferometric height estimates 

    @ARTICLE{deGraaf98:ModernSpectralEstim,
author = {DeGraaf, Stuart R.},
title = {SAR imaging via modern 2-D spectral estimation methods},
journal = {Image Processing, IEEE Transactions on},
year = {1998},
volume = {7},
pages = {729--761},
number = {5},
abstract = {Discusses the use of modern 2D spectral estimation algorithms forsynthetic aperture radar (SAR) imaging. The motivation for applyingpower spectrum estimation methods to SAR imaging is to improveresolution, remove sidelobe artifacts, and reduce speckle compared towhat is possible with conventional Fourier transform SAR imagingtechniques. This paper makes two principal contributions to the field ofadaptive SAR imaging. First, it is a comprehensive comparison of 2Dspectral estimation methods for SAR imaging. It provides a synopsis ofthe algorithms available, discusses their relative merits for SARimaging, and illustrates their performance on simulated and collectedSAR imagery. Some of the algorithms presented or their derivations arenew, as are some of the insights into or analyses of the algorithms.Second, this work develops multichannel variants of four relatedalgorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM),adaptive sidelobe reduction (ASR) and space variant apodization (SVA) toestimate both reflectivity intensity and interferometric height frompolarimetric displaced-aperture interferometric data. All of theseinterferometric variants are new. In the interferometric contest,adaptive spectral estimation can improve the height estimates through acombination of adaptive nulling and averaging. Examples illustrate thatMVM, ASR, and SVA offer significant advantages over Fourier methods forestimating both scattering intensity and interferometric height, andallow empirical comparison of the accuracies of Fourier, MVM, ASR, andSVA interferometric height estimates},
issn = {1057-7149},
keywords = {SAR Processing, Spectral Estimation, adaptive estimation, adaptive signal processing, estimation theory, image resolution, interference suppression, radar imaging, radar interference, radiowave interferometry, speckle, spectral analysis, synthetic aperture radar, 2-D spectral estimation methods, ASR, MVM, RRMVM, SVA, adaptive SAR imaging, adaptive nulling, adaptive sidelobe reduction, adaptive spectral estimation, averaging, height estimates, interferometric height, minimum variance method, multichannel variants, polarimetric displaced-aperture interferometric data, power spectrum estimation methods, reduced-rank MVM, reflectivity intensity, resolution, scattering intensity, sidelobe artifacts, space variant apodization, speckle, synthetic aperture radar imaging, MUSIC},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/deGraaf98.pdf},
timestamp = {2006.03.24},
url = {http://ieeexplore.ieee.org/iel4/83/14624/00668029.pdf} 
}


  6. Knut Eldhuset. A new fourth-order processing algorithm for spaceborne SAR. Aerospace and Electronic Systems, IEEE Transactions on, 34(3):824--835, 1998.
    Keywords: SAR Processing, digital simulation, radar theory, signal processing, spaceborne radar, synthetic aperture radar, transfer functions, azimuth lines, extended ETF, fourth-order EETF, fourth-order processing algorithm, fourth-order signal aperture radar, high quality images, integration times, phase corrections, phase preservation, range-variant phase corrections, satellite-Earth relative motion, spaceborne SAR, spatial resolution, synthetic aperture radar, two-dimensional exact transfer function.
    Abstract: A new fourth-order signal aperture radar (SAR) processingalgorithm has been developed for a general satellite-Earth relativemotion. The two-dimensional exact transfer function (ETF) is calculatedand range-variant phase corrections have been calculated in order toprocess many azimuth lines per block. The ETF together with the phasecorrections has been called the fourth-order EETF (extended ETF). It isalso shown that a fourth-order EETF is necessary to process high qualityimages from spaceborne SAR with long integration times with spatialresolution around 1 m. The algorithm is fast and is anticipated to havegood phase preservation properties 

    @ARTICLE{eldhuset98:EETF,
author = {Eldhuset, Knut},
title = {A new fourth-order processing algorithm for spaceborne SAR},
journal = {Aerospace and Electronic Systems, IEEE Transactions on},
year = {1998},
volume = {34},
pages = {824--835},
number = {3},
abstract = {A new fourth-order signal aperture radar (SAR) processingalgorithm has been developed for a general satellite-Earth relativemotion. The two-dimensional exact transfer function (ETF) is calculatedand range-variant phase corrections have been calculated in order toprocess many azimuth lines per block. The ETF together with the phasecorrections has been called the fourth-order EETF (extended ETF). It isalso shown that a fourth-order EETF is necessary to process high qualityimages from spaceborne SAR with long integration times with spatialresolution around 1 m. The algorithm is fast and is anticipated to havegood phase preservation properties},
keywords = {SAR Processing, digital simulation, radar theory, signal processing, spaceborne radar, synthetic aperture radar, transfer functions, azimuth lines, extended ETF, fourth-order EETF, fourth-order processing algorithm, fourth-order signal aperture radar, high quality images, integration times, phase corrections, phase preservation, range-variant phase corrections, satellite-Earth relative motion, spaceborne SAR, spatial resolution, synthetic aperture radar, two-dimensional exact transfer function},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/eldhuset98.pdf},
timestamp = {2006.03.24},
url = {http://ieeexplore.ieee.org/iel4/7/15279/00705890.pdf} 
}


  7. Giorgio Franceschetti, Antonio Iodice, Maurizio Migliaccio, and Daniele Riccio. A Novel Across-Track SAR Interferometry Simulator. IEEE Transactions on Geoscience and Remote Sensing, 36(3):950-962, May 1998.
    Keywords: SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Interferometry, Interferometry Simulator.
    Abstract: A novel across-track interferometric synthetic aperture radar (SAR) raw signal simulator is presented. It is based on an electromagnetic backscattering model of the scene and an accurate description of the SAR system impulse response function. A set of meaningful examples are also presented. They show that the proposed simulator is structurally consistent and correctly simulates the decorrelation effect, both in the mean and in the distribution sense. 

    @ARTICLE{francescIodMigliaRic98:Simulation,
author = {Giorgio Franceschetti and Antonio Iodice and Maurizio Migliaccio and Daniele Riccio},
title = {{A Novel Across-Track SAR Interferometry Simulator}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1998},
volume = {36},
pages = {950-962},
number = {3},
month = May,
abstract = {A novel across-track interferometric synthetic aperture radar (SAR) raw signal simulator is presented. It is based on an electromagnetic backscattering model of the scene and an accurate description of the SAR system impulse response function. A set of meaningful examples are also presented. They show that the proposed simulator is structurally consistent and correctly simulates the decorrelation effect, both in the mean and in the distribution sense.},
keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Interferometry, Interferometry Simulator},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/francescIodMigliaRic98.pdf},
url = {http://ieeexplore.ieee.org/iel4/36/14800/00673686.pdf} 
}


  8. Aruna Gunawardena and Dennis Longstaff. Wave Equation Formulation of Synthetic Aperture Radar (SAR) Algorithms in the Time-Space Domain. IEEE Transactions on Geoscience and Remote Sensing, 36(6):1995-1999, November 1998.
    Keywords: SAR Processing, Time-Space Domain Algorithm, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Comparison of Algorithms.
    Abstract: In this paper, we propose an alternative wave equationbased time-space domain synthetic aperture radar (SAR) algorithm. The proposed algorithm can be interpreted as the exact time-space domain counterpart of the wave equation-based omega-k domain SAR algorithms proposed in recent years. Links to conventional SAR and seismic migration algorithm are also established. 

    @ARTICLE{gunawardenaLongstaff98:SAR,
author = {Aruna Gunawardena and Dennis Longstaff},
title = {{Wave Equation Formulation of Synthetic Aperture Radar (SAR) Algorithms in the Time-Space Domain}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1998},
volume = {36},
pages = {1995-1999},
number = {6},
month = Nov,
abstract = {In this paper, we propose an alternative wave equationbased time-space domain synthetic aperture radar (SAR) algorithm. The proposed algorithm can be interpreted as the exact time-space domain counterpart of the wave equation-based omega-k domain SAR algorithms proposed in recent years. Links to conventional SAR and seismic migration algorithm are also established.},
keywords = {SAR Processing, Time-Space Domain Algorithm, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Comparison of Algorithms},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/gunawardenaLongstaff98.pdf},
url = {http://ieeexplore.ieee.org/iel4/36/15714/00729376.pdf} 
}


  9. R. Lanari, S. Hensley, and P.A. Rosen. Chirp z-transform based SPECAN approach for phase-preserving ScanSAR image generation. Radar, Sonar and Navigation, IEE Proceedings -, 145(5):254-261, October 1998.
    Keywords: SAR Processing, Modified SPECAN, SPECAN, Spectral Analysis, Z transforms, airborne radar, image resolution, radar imaging, radar resolution, InSAR, SAR Interferometry, radiowave interferometry, spaceborne radar, synthetic aperture radar, time-domain analysis, transient response, ScanSAR, airborne platform, algorithm, azimuth focusing, chirp z-transform, chirp-z, experiments, high resolution microwave images, image impulse response, interferometric ScanSAR systems, modified SPECAN algorithm, phase analysis, phase-preserving ScanSAR image generation, real data, scan mode synthetic aperture radar, simulated data, spaceborne platform, standard range-Doppler approach, time domain.
    Abstract: The scan mode synthetic aperture radar (ScanSAR) image impulse response is derived in the time domain, and particular attention is given to the analysis of the phase, which is important for several applications, and especially in interferometric ScanSAR systems. A new algorithm for phase-preserving azimuth focusing of ScanSAR data, that extends the basic SPECAN procedure, is presented. The proposed algorithm avoids the interpolation step needed to achieve a constant azimuth pixel spacing by replacing the standard Fourier transform used in the SPECAN procedure with an appropriate chirp z-transform. The relationship between the modified SPECAN algorithm and the standard range-Doppler approach is also discussed. Experiments on real and simulated data are carried out to validate the theory 

    @ARTICLE{lanariHensleyRosen1998Long:ModifiedSPECAN,
author = {Lanari, R. and Hensley, S. and Rosen, P.A.},
title = {Chirp z-transform based SPECAN approach for phase-preserving ScanSAR image generation},
journal = {Radar, Sonar and Navigation, IEE Proceedings -},
year = {1998},
volume = {145},
pages = {254-261},
number = {5},
month = {Oct},
abstract = {The scan mode synthetic aperture radar (ScanSAR) image impulse response is derived in the time domain, and particular attention is given to the analysis of the phase, which is important for several applications, and especially in interferometric ScanSAR systems. A new algorithm for phase-preserving azimuth focusing of ScanSAR data, that extends the basic SPECAN procedure, is presented. The proposed algorithm avoids the interpolation step needed to achieve a constant azimuth pixel spacing by replacing the standard Fourier transform used in the SPECAN procedure with an appropriate chirp z-transform. The relationship between the modified SPECAN algorithm and the standard range-Doppler approach is also discussed. Experiments on real and simulated data are carried out to validate the theory},
issn = {1350-2395},
keywords = {SAR Processing, Modified SPECAN, SPECAN, Spectral Analysis,Z transforms, airborne radar, image resolution, radar imaging, radar resolution, InSAR, SAR Interferometry, radiowave interferometry, spaceborne radar, synthetic aperture radar, time-domain analysis, transient response,ScanSAR, airborne platform, algorithm, azimuth focusing, chirp z-transform,chirp-z, experiments, high resolution microwave images, image impulse response, interferometric ScanSAR systems, modified SPECAN algorithm, phase analysis, phase-preserving ScanSAR image generation, real data, scan mode synthetic aperture radar, simulated data, spaceborne platform, standard range-Doppler approach, time domain},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/lanariHensleyRosen1998Long.pdf},
url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=741980&isnumber=15932} 
}


  10. Zheng-She Liu and Jian Li. Synthetic-aperture-radar motion compensation and feature extraction by means of a relaxation-based algorithm. J. Opt. Soc. Am. A, 15(3):599--610, 1998.
    Keywords: SAR Processing, Autofocus, Motion Compensation, MoComp, Residual Motion Errors, Airborne SAR, Phase Gradient Autofocus, PGA, RELAX, MCRELAX, Cramer-Rao Bound, Parametric Estimation. 
    @ARTICLE{liuLi98:Autofocus,
author = {Zheng-She Liu and Jian Li},
title = {Synthetic-aperture-radar motion compensation and feature extraction by means of a relaxation-based algorithm},
journal = {J. Opt. Soc. Am. A},
year = {1998},
volume = {15},
pages = {599--610},
number = {3},
keywords = {SAR Processing, Autofocus, Motion Compensation, MoComp, Residual Motion Errors, Airborne SAR, Phase Gradient Autofocus, PGA, RELAX, MCRELAX, Cramer-Rao Bound, Parametric Estimation},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/liuLi98.pdf},
publisher = {OSA},
url = {http://www.opticsinfobase.org/DirectPDFAccess/6D59F34F-BDB9-137E-C70AC82BCFBCC953_1422.pdf} 
}


  11. Lars M. H. Ulander and Per-Olov Frölind. Ultra-Wideband SAR Interferometry. IEEE Transactions on Geoscience and Remote Sensing, 36(5):1540-1550, Sept 1998.
    Keywords: SAR Processing, Interferometry, DEM Generation, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Ultra-Wideband SAR, VHF SAR, CARABAS, Airborne SAR.
    Abstract: We introduce ultra-wideband synthetic aperture radar (SAR) interferometry as a new technique for topographic height retrieval. It is based on using a SAR system with large relative bandwidth that acquires data along two parallel tracks with a separation of the same order of magnitude as the flight altitude. The complex SAR image data are resampled onto a common reference surface, filtered, and followed by a Hermitian multiplication. The resulting interferogram is shown to have a finite depth-of-focus (DOF) in terms of phase coherence. The achieved height precision is controlled by the ambiguity height, which is shown to scale to the DOF as the relative bandwidth. This means that only one fringe is within the DOF as the resolution approaches the fundamental wavelength limit; i.e., the phase is unambiguously related to topographic height. The topography may thus be determined by changing the reference surface and retrieving the height at each step. The technique is successfully demonstrated to generate fringes based on VHF-band data acquired by the CARABAS airborne SAR system. Temporal decorrelation is not a problem due to the long wavelengths nor is the effect of tropospheric delay on the retrieved height. 

    @ARTICLE{ulanderfroelind98:Interfero,
author = {Lars M. H. Ulander and Per-Olov Fr{\"o}lind},
title = {{Ultra-Wideband SAR Interferometry}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1998},
volume = {36},
pages = {1540-1550},
number = {5},
month = Sept,
abstract = {We introduce ultra-wideband synthetic aperture radar (SAR) interferometry as a new technique for topographic height retrieval. It is based on using a SAR system with large relative bandwidth that acquires data along two parallel tracks with a separation of the same order of magnitude as the flight altitude. The complex SAR image data are resampled onto a common reference surface, filtered, and followed by a Hermitian multiplication. The resulting interferogram is shown to have a finite depth-of-focus (DOF) in terms of phase coherence. The achieved height precision is controlled by the ambiguity height, which is shown to scale to the DOF as the relative bandwidth. This means that only one fringe is within the DOF as the resolution approaches the fundamental wavelength limit; i.e., the phase is unambiguously related to topographic height. The topography may thus be determined by changing the reference surface and retrieving the height at each step. The technique is successfully demonstrated to generate fringes based on VHF-band data acquired by the CARABAS airborne SAR system. Temporal decorrelation is not a problem due to the long wavelengths nor is the effect of tropospheric delay on the retrieved height.},
keywords = {SAR Processing, Interferometry, DEM Generation, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Ultra-Wideband SAR, VHF SAR, CARABAS, Airborne SAR},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/ulanderfroelind98.pdf},
url = {http://ieeexplore.ieee.org/iel4/36/15531/00718858.pdf} 
}


Conference articles

  1. Stefan Buckreuss and Ralf Horn. E-SAR P-band SAR subsystem design and RF-interference suppression. In Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS '98. 1998 IEEE International, volume 1, pages 466--468, 1998.
    Keywords: SAR Processing, airborne radar, interference suppression, microstrip antenna arrays, radar interference, radar polarimetry, synthetic aperture radar, 450 MHz, E-SAR P-band SAR subsystem design, Germany, Institut fur Hochfrequenztechnik, P-Band, P-band radar front-end, RFI Suppression, RF-interference suppression, Weilheim, carrier frequency, experimental airborne synthetic aperture radar, microstrip patch array antenna, polarimetric radar, signal bandwidth.
    Abstract: Since the beginning of 1994 the Institut f{\"u}r Hochfrequenztechnik of the German Aerospace Center (DLR) has been operating an experimental airborne SAR E-SAR with a P-band radar front-end. The microstrip patch array antenna allows a signal bandwidth of slightly more than 1037763250470f the 450 MHz carrier frequency. The radar is polarimetric on a pulse-to-pulse basis. 

    @INPROCEEDINGS{buckreussHorn98:RFI,
author = {Buckreuss, Stefan and Horn, Ralf},
title = {E-SAR P-band SAR subsystem design and RF-interference suppression},
booktitle = {Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS '98. 1998 IEEE International},
year = {1998},
volume = {1},
pages = {466--468},
abstract = {Since the beginning of 1994 the Institut f{\"u}r Hochfrequenztechnik of the German Aerospace Center (DLR) has been operating an experimental airborne SAR E-SAR with a P-band radar front-end. The microstrip patch array antenna allows a signal bandwidth of slightly more than 1037763250470f the 450 MHz carrier frequency. The radar is polarimetric on a pulse-to-pulse basis.},
keywords = {SAR Processing,airborne radar, interference suppression, microstrip antenna arrays, radar interference, radar polarimetry, synthetic aperture radar, 450 MHz, E-SAR P-band SAR subsystem design, Germany, Institut fur Hochfrequenztechnik,P-Band, P-band radar front-end,RFI Suppression, RF-interference suppression, Weilheim, carrier frequency, experimental airborne synthetic aperture radar, microstrip patch array antenna, polarimetric radar, signal bandwidth},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/buckreussHorn98.pdf} 
}


  2. Francesco Holecz, Paolo Pasquali, João Moreira, and Daniel Nüesch. Rigorous radiometric calibration of airborne AeS-1 InSAR data. In IGARSS '98, Geoscience and Remote Sensing Symposium, volume 5, pages 2442--2444, 1998.
    Keywords: SAR Processing, Radiometry, Radiometric Calibration, Airborne SAR, Topography, Interferometry, calibration, geophysical techniques, remote sensing by radar, synthetic aperture radar, 9.6 GHz, AeS-1, InSAR, X-band, airborne radar, elevation data, geophysical measurement technique, interferometric SAR, land surface, radar remote sensing, radiometric calibration, synthetic aperture radar, terrain mapping, topographic data.
    Abstract: The processing of synthetic aperture radar images usually does not 

    @INPROCEEDINGS{HoleczPasqualiMoreiraNuesch98:RadiometricCalibrationAes1Data,
author = {Holecz, Francesco and Pasquali, Paolo and Moreira, Jo{\~a}o and N{\"u}esch, Daniel},
title = {{Rigorous radiometric calibration of airborne AeS-1 InSAR data}},
booktitle = {IGARSS '98, Geoscience and Remote Sensing Symposium},
year = {1998},
volume = {5},
pages = {2442--2444},
abstract = {The processing of synthetic aperture radar images usually does not},
keywords = {SAR Processing, Radiometry, Radiometric Calibration, Airborne SAR, Topography, Interferometry, calibration, geophysical techniques, remote sensing by radar, synthetic aperture radar, 9.6 GHz, AeS-1, InSAR, X-band, airborne radar, elevation data, geophysical measurement technique, interferometric SAR, land surface, radar remote sensing, radiometric calibration, synthetic aperture radar, terrain mapping, topographic data},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/HoleczPasqualiMoreiraNuesch98.pdf},
url = {http://ieeexplore.ieee.org/iel4/5660/15200/00702240.pdf} 
}


  3. Charles V. Jakowatz, Daniel E. Wahl, and Paul H. Eichel. Refocus of constant-velocity moving targets in synthetic aperture radar imagery. In Edmund G. Zelnio, editor, , volume 3370, pages 85-95, 1998. SPIE.
    Keywords: SAR Processing, Moving Target Indication, MTI. 
    @conference{jakowatzWahlEichelRefocusMovingTargets,
author = {Charles V. Jakowatz, Jr. and Daniel E. Wahl and Paul H. Eichel},
editor = {Edmund G. Zelnio},
collaboration = {},
title = {Refocus of constant-velocity moving targets in synthetic aperture radar imagery},
publisher = {SPIE},
year = {1998},
journal = {Algorithms for Synthetic Aperture Radar Imagery V},
volume = {3370},
number = {1},
pages = {85-95},
location = {Orlando, FL, USA},
url = {http://link.aip.org/link/?PSI/3370/85/1},
doi = {10.1117/12.321814},
keywords = {SAR Processing, Moving Target Indication, MTI},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/jakowatzWahlEichelRefocusMovingTargets.pdf},
owner = {ofrey},

}


  4. Bruno Juhel, Yannick Chevalier, Marc Le Goff, Emmanuel Legros, and Georges Vezzosi. Experimental Ultra Wide Band SAR Images of Canonical Targets. In IGARSS '98, International Geoscience and Remote Sensing Symposium, volume 2, pages 1153-1155, 1998.
    Keywords: SAR Processing, Backprojection, Time Domain Backprojection, Ultra-Wideband SAR.
    Abstract: This paper describes one technique for ultra wide band (UWB) time domain radar signal processing. Usually a radar is a narrow band system, but in this case transmitted signals are nanosecond short pulses without carrier which have a spectral content from 100 MHz to 1 GHz. Time domain backprojection is used to focus SAR images. The algorithm is tested with experimental data measured with an UWB prototype radar. The configuration of this radar is described and some UWB SAR images of canonical targets are presented 

    @INPROCEEDINGS{JuhelEtAl98:Backproj,
author = {Bruno Juhel and Yannick Chevalier and Marc Le Goff and Emmanuel Legros and Georges Vezzosi},
title = {{Experimental Ultra Wide Band SAR Images of Canonical Targets}},
booktitle = {IGARSS '98, International Geoscience and Remote Sensing Symposium},
year = {1998},
volume = {2},
pages = {1153-1155},
abstract = {This paper describes one technique for ultra wide band (UWB) time domain radar signal processing. Usually a radar is a narrow band system, but in this case transmitted signals are nanosecond short pulses without carrier which have a spectral content from 100 MHz to 1 GHz. Time domain backprojection is used to focus SAR images. The algorithm is tested with experimental data measured with an UWB prototype radar. The configuration of this radar is described and some UWB SAR images of canonical targets are presented},
keywords = {SAR Processing, Backprojection, Time Domain Backprojection, Ultra-Wideband SAR},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/juhelEtAl98.pdf} 
}


  5. Bruno Juhel, Georges Vezzosi, and Marc Le Goff. Radio Frequency Interferences Suppression for Noisy Ultra Wide Band SAR Measurements. In Ultra-Wideband Short-Pulse Electromagnetics 4, 1998, pages 387-393, June 1998.
    Keywords: SAR Processing, Backprojection, Ultra-Wideband SAR, RFI Suppression.
    Abstract: A back projection algorithm dedicated to Ultra Wide Band (UWB) signals for synthetic aperture radar (SAR) imaging is described. The time domain aspect is all the more important that the transient nature of UWB signal supplies a vast amount of information on the electromagnetic scattering mechanisms. But, during UWB measurements, radio frequency interferences (RFI) can appear and obscure target detection. We have described how RFI can be an important noise source in UWB system and how they can be suppressed. The Least Mean Square (LMS) method for extracting RFI give good results, which are quantified with simulated data. Next, we would like to improve our sinusoidal model of the RFI to include a more complete description of the RFI signal and to apply the LMS algorithm to measured data 

    @INPROCEEDINGS{JuhelVezzosiLeGoff98:Backproj,
author = {Bruno Juhel and Georges Vezzosi and Marc Le Goff},
title = {{Radio Frequency Interferences Suppression for Noisy Ultra Wide Band SAR Measurements}},
booktitle = {Ultra-Wideband Short-Pulse Electromagnetics 4, 1998},
year = {1998},
pages = {387-393},
month = Jun,
abstract = {A back projection algorithm dedicated to Ultra Wide Band (UWB) signals for synthetic aperture radar (SAR) imaging is described. The time domain aspect is all the more important that the transient nature of UWB signal supplies a vast amount of information on the electromagnetic scattering mechanisms. But, during UWB measurements, radio frequency interferences (RFI) can appear and obscure target detection. We have described how RFI can be an important noise source in UWB system and how they can be suppressed. The Least Mean Square (LMS) method for extracting RFI give good results, which are quantified with simulated data. Next, we would like to improve our sinusoidal model of the RFI to include a more complete description of the RFI signal and to apply the LMS algorithm to measured data},
keywords = {SAR Processing, Backprojection, Ultra-Wideband SAR, RFI Suppression},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/JuhelVezzosiLeGoff98.pdf},
url = {http://ieeexplore.ieee.org/iel5/6640/17710/00818972.pdf} 
}


  6. Kenneth Knaell. Progress in three-dimensional SAR from curvilinear apertures. In William J. Miceli, editor, , volume 3462, pages 110-121, 1998. SPIE.
    Keywords: SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR. 
    @CONFERENCE{knaell:110,
author = {Kenneth Knaell},
title = {Progress in three-dimensional SAR from curvilinear apertures},
year = {1998},
editor = {William J. Miceli},
volume = {3462},
number = {1},
pages = {110-121},
publisher = {SPIE},
doi = {10.1117/12.326738},
journal = {Radar Processing, Technology, and Applications III},
keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR},
location = {San Diego, CA, USA},
url = {http://link.aip.org/link/?PSI/3462/110/1} 
}


  7. Riccardo Lanari, Scott Hensley, and Paul Rosen. Modified SPECAN algorithm for ScanSAR data processing. In IEEE International Geoscience and Remote Sensing Symposium, volume 2, pages 636-638, July 1998.
    Keywords: SAR Processing, Modified SPECAN, SPECAN, Spectral Analysis, geophysical signal processing, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radarSAR, ScanSAR, ScanSAR image, chirp z-transform, chirp-z, geophysical measurement technique, land surface, modified SPECAN algorithm, phase-preserving algorithm, radar imaging, radar remote sensing, range-dependent correction factor, synthetic aperture radar, terrain mapping.
    Abstract: The authors present a new phase-preserving algorithm for ScanSAR data processing that extends the SPECAN procedure. The proposed technique allows one to avoid the range dependent scaling of the azimuth pixel dimension, obtained by applying the standard SPECAN approach; this result is achieved by replacing the standard Fourier transform included in the SPECAN algorithm with a chirp z-transform, whose kernel includes a range-dependent correction factor. ScanSAR images generated via the proposed procedure have a constant azimuth pixel spacing whose dimension can be selected according to the application requirements 

    @INPROCEEDINGS{lanariHensleyRosen1998Short:ModifiedSPECAN,
author = {Lanari, Riccardo and Hensley, Scott and Rosen, Paul},
title = {Modified SPECAN algorithm for ScanSAR data processing},
booktitle = {IEEE International Geoscience and Remote Sensing Symposium},
year = {1998},
volume = {2},
pages = {636-638},
month = jul,
abstract = {The authors present a new phase-preserving algorithm for ScanSAR data processing that extends the SPECAN procedure. The proposed technique allows one to avoid the range dependent scaling of the azimuth pixel dimension, obtained by applying the standard SPECAN approach; this result is achieved by replacing the standard Fourier transform included in the SPECAN algorithm with a chirp z-transform, whose kernel includes a range-dependent correction factor. ScanSAR images generated via the proposed procedure have a constant azimuth pixel spacing whose dimension can be selected according to the application requirements},
doi = {10.1109/IGARSS.1998.699535},
keywords = {SAR Processing, Modified SPECAN, SPECAN, Spectral Analysis, geophysical signal processing, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radarSAR, ScanSAR,ScanSAR image, chirp z-transform,chirp-z, geophysical measurement technique, land surface, modified SPECAN algorithm, phase-preserving algorithm, radar imaging, radar remote sensing, range-dependent correction factor, synthetic aperture radar, terrain mapping},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/lanariHensleyRosen1998Short.pdf},
url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=699535&isnumber=15176?tag=1} 
}


  8. Li Liwei, Asif Raza, and Mao Shiyi. Improvement of rank one phase estimation (ROPE) autofocusing technique. In Signal Processing Proceedings, 1998. ICSP '98. 1998 Fourth International Conference on, volume 2, pages 1461--1464vol.2, 12-16 Oct. 1998. 
    @INPROCEEDINGS{Liwei1998,
author = {Li Liwei and Asif Raza and Mao Shiyi},
title = {Improvement of rank one phase estimation (ROPE) autofocusing technique},
booktitle = {Signal Processing Proceedings, 1998. ICSP '98. 1998 Fourth International Conference on},
year = {1998},
volume = {2},
pages = {1461--1464vol.2},
month = {12-16 Oct.},
doi = {10.1109/ICOSP.1998.770896},
owner = {ofrey} 
}


  9. F. Lombardini, H.D. Griffiths, and F. Gini. A ML multichannel ATI-SAR technique for measuring ocean surface velocities. In OCEANS '98 Conference Proceedings, volume 2, pages 778--782vol.2, 28 Sept.-1 Oct. 1998. 
    @INPROCEEDINGS{Lombardini1998,
author = {Lombardini, F. and Griffiths, H.D. and Gini, F.},
title = {A ML multichannel ATI-SAR technique for measuring ocean surface velocities},
booktitle = {OCEANS '98 Conference Proceedings},
year = {1998},
volume = {2},
pages = {778--782vol.2},
month = {28 Sept.-1 Oct.},
doi = {10.1109/OCEANS.1998.724344},
owner = {ofrey} 
}


  10. F. Lombardini and P. Lombardo. A ML thinned array SAR interferometric sensor for high accuracy absolute phase retrieval. In Radar Conference, 1998. RADARCON 98. Proceedings of the 1998 IEEE, pages 263--268, 11-14 May 1998. 
    @INPROCEEDINGS{Lombardini1998a,
author = {Lombardini, F. and Lombardo, P.},
title = {A ML thinned array SAR interferometric sensor for high accuracy absolute phase retrieval},
booktitle = {Radar Conference, 1998. RADARCON 98. Proceedings of the 1998 IEEE},
year = {1998},
pages = {263--268},
month = {11-14 May},
doi = {10.1109/NRC.1998.678012},
owner = {ofrey} 
}


  11. Richard T. Lord and Michael R. Inggs. Approaches to RF interference suppression for VHF/UHF synthetic aperture radar. In Communications and Signal Processing, 1998. COMSIG '98. Proceedings of the 1998 South African Symposium on, pages 95--100, 1998.
    Keywords: SAR Processing, adaptive filters, adaptive signal processing, interference suppression, least mean squares methods, radar imaging, radar interference, synthetic aperture radar, LMS adaptive filter, P-Band, RF interference suppression, RFI Suppression, SAR imagery, VHF/UHF SAR applications, VHF/UHF synthetic aperture radar, coherent subtraction algorithms, filter approaches, image quality, interference power, least-mean-squared filter, radio frequency interference, receiver noise, spectral estimation.
    Abstract: An increasing amount of interest has developed in VHF/UHF SAR applications. Unfortunately the VHF-UHF portion of the spectrum is already in heavy use by other services, such as television and mobile communications. Even in remote locations the interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity and severely degrading the image quality. This paper addresses the problem of radio frequency (RF) interference and its impact on SAR imagery. Several RF interference suppression methods are described and discussed. These include spectral estimation and coherent subtraction algorithms, as well as various filter approaches. The least-mean-squared (LMS) adaptive filter is described in detail, and its effectiveness in suppressing RF interference is demonstrated on simulated data and on real P-band data. 

    @INPROCEEDINGS{lordInggs98:RFI,
author = {Lord, Richard T. and Inggs, Michael R.},
title = {Approaches to RF interference suppression for VHF/UHF synthetic aperture radar},
booktitle = {Communications and Signal Processing, 1998. COMSIG '98. Proceedings of the 1998 South African Symposium on},
year = {1998},
pages = {95--100},
abstract = {An increasing amount of interest has developed in VHF/UHF SAR applications. Unfortunately the VHF-UHF portion of the spectrum is already in heavy use by other services, such as television and mobile communications. Even in remote locations the interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity and severely degrading the image quality. This paper addresses the problem of radio frequency (RF) interference and its impact on SAR imagery. Several RF interference suppression methods are described and discussed. These include spectral estimation and coherent subtraction algorithms, as well as various filter approaches. The least-mean-squared (LMS) adaptive filter is described in detail, and its effectiveness in suppressing RF interference is demonstrated on simulated data and on real P-band data.},
keywords = {SAR Processing, adaptive filters, adaptive signal processing, interference suppression, least mean squares methods, radar imaging, radar interference, synthetic aperture radar, LMS adaptive filter, P-Band, RF interference suppression, RFI Suppression, SAR imagery, VHF/UHF SAR applications, VHF/UHF synthetic aperture radar, coherent subtraction algorithms, filter approaches, image quality, interference power, least-mean-squared filter, radio frequency interference, receiver noise, spectral estimation},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/lordInggs98.pdf},
url = {http://ieeexplore.ieee.org/iel4/5945/15887/00736929.pdf} 
}


  12. Stefan Nilsson and Lars-Erik Andersson. Application of Fast Backprojection Techniques for some Inverse Problems of Synthetic Aperture Radar. In Edmund G. Zelnio, editor, Algorithms for Synthetic Aperture Radar Imagery V, volume SPIE # 3370, pages 62-72, 1998.
    Keywords: SAR Processing, Backprojection, Fast Backprojection, Quadtree Processing, Time Domain Backprojection, Circular Averages, Wideband SAR, Focusing, Motion Compensation.
    Abstract: In certain radar imaging applications one encounters the problem of reconstructing a reflectivityfunction from information about its averages over circles with center on a straight line. A robust inversion method is afiltered backprojection method, similar to the one used in medical tomography. We will present a fast algorithm for this backprojection operator. Numerical examples are given. 

    @INPROCEEDINGS{NilssonAndersson98:Backprojection,
author = {Stefan Nilsson and Lars-Erik Andersson},
title = {{Application of Fast Backprojection Techniques for some Inverse Problems of Synthetic Aperture Radar}},
booktitle = {Algorithms for Synthetic Aperture Radar Imagery V},
year = {1998},
editor = {Edmund G. Zelnio},
volume = SPIE # {3370},
pages = {62-72},
abstract = {In certain radar imaging applications one encounters the problem of reconstructing a reflectivityfunction from information about its averages over circles with center on a straight line. A robust inversion method is afiltered backprojection method, similar to the one used in medical tomography. We will present a fast algorithm for this backprojection operator. Numerical examples are given.},
keywords = {SAR Processing, Backprojection, Fast Backprojection, Quadtree Processing, Time Domain Backprojection, Circular Averages, Wideband SAR, Focusing, Motion Compensation},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/NilssonAndersson98.pdf},
url = {http://spie.org/scripts/abstract.pl?bibcode=1998SPIE5.082781e-27033705.316882e-2705.089991e-2705.060922e-26962N&page=1&qs=spie} 
}


  13. Richard Rau and James H. McClellan. A Directional Image Decomposition for Ultra-Wideband SAR. In ICASSP '98, International Conference on Acoustics, Speech, and Signal Processing, volume 5, pages 2877-2880, May 1998.
    Keywords: SAR Processing, Backprojection, Ultra-Wideband SAR, Directional Filterbanks.
    Abstract: This paper presents a theoretical analysis of the structure of wide angle, ultra-wideband SAR images formed by a constant integration angle backprojection image former. It is shown that the effects of the image former can be modeled as a filtering operation on the original data. Furthermore, SAR images for different squint angles can be obtained from the original images by directional filtering. As a result, it is shown that perfect reconstructing directional filterbanks can be used as a unitary transform between SAR images and a 3-D representation containing additional aspect-angle information. It is demonstrated, how this new representation can be used to enhance targets. 

    @INPROCEEDINGS{RauMcClellan98:Backproj,
author = {Richard Rau and James H. McClellan},
title = {{A Directional Image Decomposition for Ultra-Wideband SAR}},
booktitle = {ICASSP '98, International Conference on Acoustics, Speech, and Signal Processing},
year = {1998},
volume = {5},
pages = {2877-2880},
month = May,
abstract = {This paper presents a theoretical analysis of the structure of wide angle, ultra-wideband SAR images formed by a constant integration angle backprojection image former. It is shown that the effects of the image former can be modeled as a filtering operation on the original data. Furthermore, SAR images for different squint angles can be obtained from the original images by directional filtering. As a result, it is shown that perfect reconstructing directional filterbanks can be used as a unitary transform between SAR images and a 3-D representation containing additional aspect-angle information. It is demonstrated, how this new representation can be used to enhance targets.},
keywords = {SAR Processing, Backprojection, Ultra-Wideband SAR, Directional Filterbanks},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/rauMcClellan98.pdf} 
}


  14. Andreas Reigber and Andreas Ulbricht. P-band repeat-pass interferometry with the DLR experimental SAR. In Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS '98. 1998 IEEE International, volume 4, pages 1914--1916, 1998.
    Keywords: SAR Processing, airborne radar, geophysical techniques, remote sensing by radar, synthetic aperture radar, DLR experimental SAR, ESAR, P-Band, RF interference removal, RFI Suppression, SAR interferometry, Interferometry, UHF, geophysical measurement technique, ground parameters, land surface, radar remote sensing, repeat-pass interferometry, repeat-pass mode, surface topography, synthetic aperture radar, terrain mapping.
    Abstract: SAR interferometry is a powerful tool for the determination of surface topography and for estimation of ground parameters. In particular the analysis of different frequencies has the capability to provide a broad set of useful information. Therefore long wavelengths like the P-band of great interest, because they often show different interactions with scatterers than shorter wavelengths like the C-band. The authors address the implementation of a P-band repeat-pass mode for the DLR's experimental SAR (ESAR), including the problematic removal of RF-interferences in the data. Recent results on a test site in Solothurn/Switzerland are shown. 

    @INPROCEEDINGS{reigberUlbricht98:InterferoRFI,
author = {Reigber, Andreas and Ulbricht, Andreas},
title = {P-band repeat-pass interferometry with the DLR experimental SAR},
booktitle = {Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS '98. 1998 IEEE International},
year = {1998},
volume = {4},
pages = {1914--1916},
abstract = {SAR interferometry is a powerful tool for the determination of surface topography and for estimation of ground parameters. In particular the analysis of different frequencies has the capability to provide a broad set of useful information. Therefore long wavelengths like the P-band of great interest, because they often show different interactions with scatterers than shorter wavelengths like the C-band. The authors address the implementation of a P-band repeat-pass mode for the DLR's experimental SAR (ESAR), including the problematic removal of RF-interferences in the data. Recent results on a test site in Solothurn/Switzerland are shown.},
keywords = {SAR Processing, airborne radar, geophysical techniques, remote sensing by radar, synthetic aperture radar, DLR experimental SAR, ESAR, P-Band, RF interference removal, RFI Suppression, SAR interferometry, Interferometry, UHF, geophysical measurement technique, ground parameters, land surface, radar remote sensing, repeat-pass interferometry, repeat-pass mode, surface topography, synthetic aperture radar, terrain mapping},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/reigberUlbricht98.pdf},
url = {http://ieeexplore.ieee.org/iel4/5660/15207/00703693.pdf} 
}


  15. Olle Seger, Magnus Herberthson, and Hans Hellsten. Real time SAR processing of low frequency ultra wide band radar data. In Proc. of EUSAR '98 - European Conference on Synthetic Aperture Radar, pages 489-492, May 1998.
    Keywords: SAR Processing, Backprojection, Time-Domain Backprojection, Local Backprojection, Real Time Operation, Ultra-Wideband SAR, FOPEN, Image processing, Ground Penetrating Radar, Low-Frequency SAR, Image Reconstruction, Radar Resolution, Parallel Processing.
    Abstract: CARABAS (Coherent All RAdio BAnd Sensing) is a synthetic aperture radar with high relative bandwidth. Furthermore, CARABAS operates at radio band frequencies, which enables the radar to penetrate foliage. In this paper, we propose and analyze a reconstruction algorithm suitable for parallel implementation. The core idea of the method is a subdivision of the radar raw data into subapertures, from which coarse resolution subimages can be reconstructed. These subimages are then distributed to the nodes of a powerful parallel computer in order to achieve fine resolution at real-time rate. 

    @INPROCEEDINGS{segerHerberthsonHellsten98:LocalBackprojection,
author = {Seger, Olle and Herberthson, Magnus and Hellsten, Hans},
title = {Real time SAR processing of low frequency ultra wide band radar data},
booktitle = {Proc. of EUSAR '98 - European Conference on Synthetic Aperture Radar},
year = {1998},
pages = {489-492},
month = {May},
abstract = {CARABAS (Coherent All RAdio BAnd Sensing) is a synthetic aperture radar with high relative bandwidth. Furthermore, CARABAS operates at radio band frequencies, which enables the radar to penetrate foliage. In this paper, we propose and analyze a reconstruction algorithm suitable for parallel implementation. The core idea of the method is a subdivision of the radar raw data into subapertures, from which coarse resolution subimages can be reconstructed. These subimages are then distributed to the nodes of a powerful parallel computer in order to achieve fine resolution at real-time rate.},
keywords = {SAR Processing, Backprojection, Time-Domain Backprojection, Local Backprojection, Real Time Operation, Ultra-Wideband SAR, FOPEN, Image processing; Ground Penetrating Radar, Low-Frequency SAR, Image Reconstruction, Radar Resolution, Parallel Processing},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/segerHerberthsonHellsten98.pdf} 
}


  16. David Small, Francesco Holecz, Erich Meier, and Daniel Nüesch. Absolute radiometric correction in rugged terrain: A plea for integrated radar brightness. In IGARSS '98, International Geoscience and Remote Sensing Symposium, volume 1, pages 330--332, 1998.
    Keywords: geophysical signal processing, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, absolute radiometric correction, biomass estimation, geophysical measurement technique, integrated radar brightness, integrative faceted heteromorphic approach, land surface, multimode SAR imagery, multimode image comparison, radar remote sensing, radiometric normalisation, rugged terrain, spaceborne radar, synthetic aperture radar, terrain mapping, terrain-induced variation.
    Abstract: Rigorous intercomparison of multimode SAR imagery requires not 

    @INPROCEEDINGS{SmallHoleczMeierNuesch98:RadiometricCorrectionIGARSS,
author = {Small, David and Holecz, Francesco and Meier, Erich and N{\"u}esch, Daniel},
title = {{Absolute radiometric correction in rugged terrain: A plea for integrated radar brightness}},
booktitle = {IGARSS '98, International Geoscience and Remote Sensing Symposium},
year = {1998},
volume = {1},
pages = {330--332},
abstract = {Rigorous intercomparison of multimode SAR imagery requires not},
keywords = {geophysical signal processing, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, absolute radiometric correction, biomass estimation, geophysical measurement technique, integrated radar brightness, integrative faceted heteromorphic approach, land surface, multimode SAR imagery, multimode image comparison, radar remote sensing, radiometric normalisation, rugged terrain, spaceborne radar, synthetic aperture radar, terrain mapping, terrain-induced variation},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/SmallHoleczMeierNuesch98IGARSS.pdf},
url = {http://ieeexplore.ieee.org/iel4/5660/15194/00702895.pdf} 
}


  17. David Small, Francesco Holecz, Erich Meier, and Daniel Nüesch. Radiometric Normalization for Multimode Image Comparison. In Proc. of EUSAR '98 - European Conference on Synthetic Aperture Radar, pages 191-194, 1998.
    Keywords: SAR Processing, SAR Geocoding, Geocoding, Calibration, Radiometric Calibration, Radiometric Correction, Digital Elevation Model, Image Simulation, Terrain-Geocoding.
    Abstract: Intercomparison of backscatter collected by SAR sensors at heterogeneous radar look angles gives rise to highly variable ground areas being associated with each pixel location within a radar geometry (slant or ground range) image. Many elements within a digital elevation model (in map geometry) can be mapped to a single location in the radar image (range / Doppler coordinates). An image simulation technique uses a faceted high resolution elevation model to integrate all backscatter returned to each range and Doppler location in the radar image (incorporating knowledge of local radar shadow). Modelling the imaging process in this manner, a map of illuminated area is produced in radar geometry, and used to normalize the true backscatter returned by the radar sensor. Although radar shadow must be considered specially, no extraordinary treatment is required of layover regions, as they are correctly accounted for by integration of the illuminated area. The image simulation approach improves on the conventional consideration of 2D incidence angles, as the 3D configuration defining the illuminated area (in both the range and azimuth dimensions) is captured. RADARSAT images acquired over Switzerland are used to demonstrate the benefit of such normalization for thematic interpretation. A high resolution digital elevation model (DEM) with 25m pixel spacing is used as input to the image simulation. The deterioration of the normalization with progressively poorer input DEMs is studied empirically to gauge the required DEM resolution for acceptable normalization of images acquired over pre-alpine topography. 

    @INPROCEEDINGS{smallHoleczMeierNueesch98:RadiometricNorm,
author = {David Small and Francesco Holecz and Erich Meier and Daniel N{\"u}esch},
title = {Radiometric Normalization for Multimode Image Comparison},
booktitle = {Proc. of EUSAR '98 - European Conference on Synthetic Aperture Radar},
year = {1998},
pages = {191-194},
abstract = {Intercomparison of backscatter collected by SAR sensors at heterogeneous radar look angles gives rise to highly variable ground areas being associated with each pixel location within a radar geometry (slant or ground range) image. Many elements within a digital elevation model (in map geometry) can be mapped to a single location in the radar image (range / Doppler coordinates). An image simulation technique uses a faceted high resolution elevation model to integrate all backscatter returned to each range and Doppler location in the radar image (incorporating knowledge of local radar shadow). Modelling the imaging process in this manner, a map of illuminated area is produced in radar geometry, and used to normalize the true backscatter returned by the radar sensor. Although radar shadow must be considered specially, no extraordinary treatment is required of layover regions, as they are correctly accounted for by integration of the illuminated area. The image simulation approach improves on the conventional consideration of 2D incidence angles, as the 3D configuration defining the illuminated area (in both the range and azimuth dimensions) is captured. RADARSAT images acquired over Switzerland are used to demonstrate the benefit of such normalization for thematic interpretation. A high resolution digital elevation model (DEM) with 25m pixel spacing is used as input to the image simulation. The deterioration of the normalization with progressively poorer input DEMs is studied empirically to gauge the required DEM resolution for acceptable normalization of images acquired over pre-alpine topography.},
keywords = {SAR Processing, SAR Geocoding, Geocoding, Calibration, Radiometric Calibration,Radiometric Correction,Digital Elevation Model, Image Simulation, Terrain-Geocoding},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/smallHoleczMeierNueesch98.pdf},
url = {http://www.geo.uzh.ch/publications/daves/1998/Small_EUSAR_1998.pdf} 
}


  18. Mehrdad Soumekh. Range Stacking: An Interpolation-free SAR Reconstruction Algorithm. In Edmund G. Zelnio, editor, Algorithms for Synthetic Aperture Radar Imagery V, volume SPIE # 3370, pages 13-24, 1998.
    Keywords: SAR Processing, Range Stacking Algorithm, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Backprojection, Wideband SAR, Squinted SAR, FOPEN, Motion Compensation.
    Abstract: A method for digital image formation in Synthetic Aperture Radar (SAR) systems is presented. The proposed approach is based on the wavefront reconstruction theory for SAR imaging systems. However, this is achieved without image formation in the spatial frequency domain of the target function which requires interpolation. The proposed method forms the target function at individual range points within the radar range swath; this is referred to as range stacking. The range stacking reconstruction method is applicable in stripmap and spotlight (broadside and squint) SAR systems. Results using a wide-beamwidth FOliage PENetrating (FOPEN) SAR database are provided, and the effect of beamwidth filtering on the signature of moving targets in the imaging scene is shown. 

    @INPROCEEDINGS{Soumekh98:,
author = {Mehrdad Soumekh},
title = {{Range Stacking: An Interpolation-free SAR Reconstruction Algorithm}},
booktitle = {Algorithms for Synthetic Aperture Radar Imagery V},
year = {1998},
editor = {Edmund G. Zelnio},
volume = SPIE # {3370},
pages = {13-24},
abstract = {A method for digital image formation in Synthetic Aperture Radar (SAR) systems is presented. The proposed approach is based on the wavefront reconstruction theory for SAR imaging systems. However, this is achieved without image formation in the spatial frequency domain of the target function which requires interpolation. The proposed method forms the target function at individual range points within the radar range swath; this is referred to as range stacking. The range stacking reconstruction method is applicable in stripmap and spotlight (broadside and squint) SAR systems. Results using a wide-beamwidth FOliage PENetrating (FOPEN) SAR database are provided, and the effect of beamwidth filtering on the signature of moving targets in the imaging scene is shown.},
keywords = {SAR Processing, Range Stacking Algorithm, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Backprojection, Wideband SAR, Squinted SAR, FOPEN, Motion Compensation},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/Soumekh98.pdf},
url = {http://spiedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PSISDG003370000001000013000001&idtype=cvips&gifs=yes} 
}


  19. D.G. Thompson, J.S. Bates, D.V. Arnold, David G. Long, and A. Robertson. Range dependent phase gradient autofocus. In IEEE International Geoscience and Remote Sensing Symposium Proceedings, IGARSS '98, volume 5, pages 2634--2636, 6-10 July 1998.
    Keywords: SAR Processing, Autofocus, Phase Gradient Autofocus, PGA, Range-dependent.
    Abstract: The Phase Gradient Autofocus (PGA) algorithm has been widely used in Spotlight Synthetic Aperture Radar (SAR) to remove motion-induced blurs in the images. The PGA algorithm has been proven to be a superior autofocus method. PGA assumes a narrow beam, which is valid for most SAR systems. However, lower altitude SAR have large range dependencies that cannot be ignored. A new phase estimator for PGA is introduced and extended to allow range dependence. An ERS-1 image of Death Valley is used in simulations comparing the new estimator to the widely used maximum likelihood approach and in demonstrating the range-dependent PGA algorithm. 

    @INPROCEEDINGS{thompsonBatesArnoldLong1998:PGA,
author = {Thompson, D.G. and Bates, J.S. and Arnold, D.V. and Long, David G. and Robertson, A.},
title = {Range dependent phase gradient autofocus},
booktitle = {IEEE International Geoscience and Remote Sensing Symposium Proceedings, IGARSS '98},
year = {1998},
volume = {5},
pages = {2634--2636},
month = {6-10 July},
abstract = {The Phase Gradient Autofocus (PGA) algorithm has been widely used in Spotlight Synthetic Aperture Radar (SAR) to remove motion-induced blurs in the images. The PGA algorithm has been proven to be a superior autofocus method. PGA assumes a narrow beam, which is valid for most SAR systems. However, lower altitude SAR have large range dependencies that cannot be ignored. A new phase estimator for PGA is introduced and extended to allow range dependence. An ERS-1 image of Death Valley is used in simulations comparing the new estimator to the widely used maximum likelihood approach and in demonstrating the range-dependent PGA algorithm.},
doi = {10.1109/IGARSS.1998.702303},
keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus, PGA, Range-dependent},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/thompsonBatesArnoldLong1998.pdf},
url = {http://ieeexplore.ieee.org/iel4/5660/15200/00702303.pdf} 
}


Miscellaneous

  1. Clint Slatton. Improving Segmented INSAR Processing Using Presumming. , 1998.
    Keywords: SAR Processing, InSAR, TOPSAR, Presumming, Range-Doppler Algorithm, Azimuth Processing, omega-k Algorithm.
    Abstract: Literature Survey
    Comments: +/- Not much on presumming, but generally a good introduction to some SAR concepts. 

    @UNPUBLISHED{Sla98:Improving,
author = {Clint Slatton},
title = {{Improving Segmented INSAR Processing Using Presumming}},
year = {1998},
abstract = {Literature Survey},
comments = {+/- Not much on presumming, but generally a good introduction to some SAR concepts.},
keyword = {SAR Processing, InSAR, TOPSAR, Presumming, Range-Doppler Algorithm, Azimuth Processing, omega-k Algorithm},
owner = {ofrey},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/slaton98.pdf},
url = {http://www.ae.utexas.edu/~slatton/} 
}



BACK TO INDEX



Disclaimer:

Please note that access to full text PDF versions of papers is restricted to the Remote Sensing Laboratories of the University of Zürich.
Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright.

This collection of SAR literature is far from being complete.
It is rather a collection of papers which I store in my literature data base. Hence, the list of publications under PUBLICATIONS OF AUTHOR'S NAME should NOT be mistaken for a complete bibliography of that author.



Last modified: Wed Sep 8 19:32:46 2010
Author: Othmar Frey , Remote Sensing Laboratories (RSL), University of Zurich, Switzerland .

This document was translated from BibTEX by bibtex2html