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BACK TO INDEX Publications of year 1992 Articles in journal or book chapters
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| Abstract: | Focusing of SAR data requires a space-variant two-dimensional correlation. Different algorithms are compared with each other in terms of their focusing quality and their ability to handle the space-variance of the correlation kernel: the range-Doppler approach with and without secondary range compression, modified range-Doppler algorithms, and four versions of the wavenumber domain processor. The phase aberrations of the different algorithms are given in analytic form. Numerical examples are presented for Seasat and ERS-1. A novel systems theoretical derivation of the wavenumber domain algorithm is presented. |
@ARTICLE{bamler92:Comparison,
author = {Richard Bamler},
title = {{A Comparison of Range-Doppler and Wavenumber Domain SAR Focusing Algorithms}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1992},
volume = {30},
pages = {706-713},
number = {4},
month = July,
abstract = {Focusing of SAR data requires a space-variant two-dimensional correlation. Different algorithms are compared with each other in terms of their focusing quality and their ability to handle the space-variance of the correlation kernel: the range-Doppler approach with and without secondary range compression, modified range-Doppler algorithms, and four versions of the wavenumber domain processor. The phase aberrations of the different algorithms are given in analytic form. Numerical examples are presented for Seasat and ERS-1. A novel systems theoretical derivation of the wavenumber domain algorithm is presented.},
keywords = {SAR Processing, Range-Doppler Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Secondary Range Compression, Comparison of Algorithms},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/bamlertgars92.pdf}
}
Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Multiple PRF Technique, Range Cross-Correlation Technique, Clutterlock, SIR-C.
| Abstract: | Estimation of the Doppler centroid ambiguity is a necessary element of the signal processing for synthetic aperture radar (SAR) systems with large antenna pointing errors. Without proper resolution of the Doppler centroid estimation (DCE) ambiguity, the image quality will be degraded in the system impulse response function and the geometric fidelity. Two techniques for resolution of DCE ambiguity for the spaceborne SAR are presented in this paper. They include a brief review of the range cross-correlation technique and presentation of a new technique using multiple pulse repetition frequencies (PRFs). We formulate an algorithm employing simple integer arithmetic for radar systems, such as moving target indicator radar (MTIR) systems, where the PRFs contain a large common divisor. For SAR systems, where other performance factors control selection of the PRFs, an algorithm is devised to resolve the ambiguity that uses PRFs of arbitrary numerical values. The performance of this multiple PRF technique is analyzed based on a statistical error model. An example is presented that demonstrates for the Shuttle Imaging Radar-C (SIR-C) C-band SAR, the probability of correct ambiguity resolution is higher than 95 percent for antenna attitude errors as large as 3?. |
@ARTICLE{ChangCurl92:Doppler,
author = {C. Y. Chang and John C. Curlander},
title = {{Application of the Multiple PRF Technique to Resolve Doppler Centroid Estimation Ambiguity for Spaceborne SAR}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1992},
volume = {30},
pages = {941-949},
number = {5},
month = Sept,
abstract = {Estimation of the Doppler centroid ambiguity is a necessary element of the signal processing for synthetic aperture radar (SAR) systems with large antenna pointing errors. Without proper resolution of the Doppler centroid estimation (DCE) ambiguity, the image quality will be degraded in the system impulse response function and the geometric fidelity. Two techniques for resolution of DCE ambiguity for the spaceborne SAR are presented in this paper. They include a brief review of the range cross-correlation technique and presentation of a new technique using multiple pulse repetition frequencies (PRFs). We formulate an algorithm employing simple integer arithmetic for radar systems, such as moving target indicator radar (MTIR) systems, where the PRFs contain a large common divisor. For SAR systems, where other performance factors control selection of the PRFs, an algorithm is devised to resolve the ambiguity that uses PRFs of arbitrary numerical values. The performance of this multiple PRF technique is analyzed based on a statistical error model. An example is presented that demonstrates for the Shuttle Imaging Radar-C (SIR-C) C-band SAR, the probability of correct ambiguity resolution is higher than 95 percent for antenna attitude errors as large as 3?.},
keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Multiple PRF Technique, Range Cross-Correlation Technique, Clutterlock, SIR-C},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/changCurl92.pdf}
}
Keywords: SAR Processing, Azimuth Processing, Range-Doppler Algorithm, Range Migration Algorithm, Wavenumber Domain Algorithm, omega-k, Point Target Transfer Funtion, Two-Dimensional Fourier Transform, Doppler Centroid, Doppler Rate Estimation, Autofocus.
| Abstract: | The two-dimensional transfer funtions of several synthetic aperture radar (SAR) focussing algorithms are derived considering the spaceborne SAR environments. The formulation includes the factors of the earth rotation and the antenna squint angles. The resultant functions are explicitly expressed in terms of Doppler centroid frequency and Doppler frequency rate, which can be conveniently and accurately estimated from the SAR data. Point target simulation results show that the algorithm based on the two-dimensional Fourier transformation out-performs the one-dimensional one for processing data acquired from high squint angles. The two-dimensional Fourier transformation approach appears to be a viable and simple solution for the processor design of future spceborne SAR systems. |
@ARTICLE{Cur92:SARProc,
author = {C. Y. Chang and M. Jin and John C. Curlander},
title = {{SAR Processing Based on the Exact Two-Dimensional Transfer Function}},
journal = {IGARSS '92, International Geoscience and Remote Sensing Symposium},
year = {1992},
pages = {355-359},
month = may,
abstract = {The two-dimensional transfer funtions of several synthetic aperture radar (SAR) focussing algorithms are derived considering the spaceborne SAR environments. The formulation includes the factors of the earth rotation and the antenna squint angles. The resultant functions are explicitly expressed in terms of Doppler centroid frequency and Doppler frequency rate, which can be conveniently and accurately estimated from the SAR data. Point target simulation results show that the algorithm based on the two-dimensional Fourier transformation out-performs the one-dimensional one for processing data acquired from high squint angles. The two-dimensional Fourier transformation approach appears to be a viable and simple solution for the processor design of future spceborne SAR systems.},
comment = {++ Overview of 4 azmuth processing algorithms: * Exact Transfer Function Algorithm (ETF) * Range-Doppler Algorithm (RD) * Secondary Range Compression Algorithm (SRC) * Squint Imaging Mode Algorithm (SIM) For each of them, the point target transfer function is given and results are discussed.},
keywords = {SAR Processing, Azimuth Processing, Range-Doppler Algorithm, Range Migration Algorithm, Wavenumber Domain Algorithm, omega-k, Point Target Transfer Funtion, Two-Dimensional Fourier Transform, Doppler Centroid, Doppler Rate Estimation, Autofocus},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/Curlander92.pdf}
}
Keywords: SAR Processing, Doppler Rate Estimation, Autofocus, Airborne SAR.
| Abstract: | High-resolution synthetic aperture radar (SAR) imaging requires the motion of the radar platform to be known very accurately. Otherwise, phase errors are induced in the processing of the raw SAR data, and bad focusing results. In particular, a constant error in the measured along-track velocity or the cross-track acceleration leads to a phase error that varies quadratically over the synthetic aperture. The process of estimating this quadratic phase error directly from the radar data is termed autofocus. A novel autofocus algorithm with a computational complexity which is at least an order of magnitude lower than that of other algorithms providing comparable accuracies is presented. The algorithm has been tested on data from the Danish Airborne SAR, and the performance is compared with that of the traditional map drift algorithm. |
@ARTICLE{Dal92:Fast,
author = {Jorgen Dall},
title = {{A Fast Autofocus Algorithm for Synthetic Aperture Radar Processing}},
journal = {IEEE International Conference on Acoustics, Speech, and Signal Processing ICASSP},
year = {1992},
volume = {3},
pages = {5-8},
month = sep,
abstract = {High-resolution synthetic aperture radar (SAR) imaging requires the motion of the radar platform to be known very accurately. Otherwise, phase errors are induced in the processing of the raw SAR data, and bad focusing results. In particular, a constant error in the measured along-track velocity or the cross-track acceleration leads to a phase error that varies quadratically over the synthetic aperture. The process of estimating this quadratic phase error directly from the radar data is termed autofocus. A novel autofocus algorithm with a computational complexity which is at least an order of magnitude lower than that of other algorithms providing comparable accuracies is presented. The algorithm has been tested on data from the Danish Airborne SAR, and the performance is compared with that of the traditional map drift algorithm.},
keywords = {SAR Processing, Doppler Rate Estimation, Autofocus, Airborne SAR},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/Dal92.pdf}
}
Keywords: SAR Processing, Spotlight SAR, Backprojection, Convolution Backprojection.
| Abstract: | Synthetic aperture radar (SAR) image reconstruction falls into the class of inverse (deconvolution) problems. A spotlight mode SAR system obtains line integrals (projections) of the ground reflectivity at various look angles as the radar platform progresses along the flight trajectory. The image of the ground area is then reconstructed from this set of projections. Conventionally, the SAR image has been produced by a direct Fourier reconstruction algorithm referred to here as the 2-D inverse FFT method. This method has two major problems: 1) due to the batch processing nature of the FFT, all returns must be recorded before the image processing can begin, and 2) a polar-to-cartesian interpolation, which is computationally intensive and error prone due to interpolation inaccuracies, is necessary before a 2-D inverse FFT can be performed. In this paper, a method based on a convolution backprojection (CBP) algorithm is presented. CBP is a widely used technique in computer-aided tomography (CAT). The CBP algorithm has been modified and applied to image reconstruction from SAR data. A quantitative evaluation using computer simulation of the CBP algorithm for spotlight mode SAR is presented. Its performance is then compared with the 2-D inverse FFT method with respect to the multiplicative noise ratio (MNR). Conclusions are supported by a reconstruction example on real SAR data collected by the Lincoln Laboratory's high resolution (0.3 m) radar. |
@ARTICLE{DesaiJenkins92:Backprojection,
author = {Mita D. Desai and W. Kenneth Jenkins},
title = {{Convolution Backprojection Image Reconstruction for Spotlight Mode Synthetic Aperture Radar}},
journal = {IEEE Transactions on Image Processing},
year = {1992},
volume = {1},
pages = {505 - 517},
number = {4},
month = Oct,
abstract = {Synthetic aperture radar (SAR) image reconstruction falls into the class of inverse (deconvolution) problems. A spotlight mode SAR system obtains line integrals (projections) of the ground reflectivity at various look angles as the radar platform progresses along the flight trajectory. The image of the ground area is then reconstructed from this set of projections. Conventionally, the SAR image has been produced by a direct Fourier reconstruction algorithm referred to here as the 2-D inverse FFT method. This method has two major problems: 1) due to the batch processing nature of the FFT, all returns must be recorded before the image processing can begin, and 2) a polar-to-cartesian interpolation, which is computationally intensive and error prone due to interpolation inaccuracies, is necessary before a 2-D inverse FFT can be performed. In this paper, a method based on a convolution backprojection (CBP) algorithm is presented. CBP is a widely used technique in computer-aided tomography (CAT). The CBP algorithm has been modified and applied to image reconstruction from SAR data. A quantitative evaluation using computer simulation of the CBP algorithm for spotlight mode SAR is presented. Its performance is then compared with the 2-D inverse FFT method with respect to the multiplicative noise ratio (MNR). Conclusions are supported by a reconstruction example on real SAR data collected by the Lincoln Laboratory's high resolution (0.3 m) radar.},
keywords = {SAR Processing, Spotlight SAR, Backprojection, Convolution Backprojection},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/desaiJenkins92.pdf}
}
Keywords: SAR Processing, Forest, Forest parameters, biomass, C-band, Duke, France, L-band, Landes, North Carolina, P-band, SAR data, United States, age, coniferous forest biomass, maritime pines, plantations, radar backscatter, remote sensing, backscatter, ecology, forestry, remote sensing by radar;.
| Abstract: | Two independent experimental efforts have examined the dependence of radar backscatter on above-ground biomass of monospecie conifer forests using polarimetric airborne SAR data at P-, L- and C-bands. Plantations of maritime pines near Landes, France, range in age from 8 to 46 years with above-ground biomass between 5 and 105 tons/ha. Loblolly pine stands established on abandoned agricultural fields near Duke, NC, range in age from 4 to 90 years and extend the range of above-ground biomass to 560 tons/ha for the older stands. These two experimental forests are largely complementary with respect to biomass. Radar backscatter is found to increase approximately linearly with increasing biomass until it saturates at a biomass level that depends on the radar frequency. The biomass saturation level is about 200 tons/ha at P-band and 100 tons/ha at L-band, and the C-band backscattering coefficient shows much less sensitivity to total above-ground biomass |
@ARTICLE{DobsonUlabyLeToanBeaudoinKasischkeChristensen1992:BiomassBackscatter,
author={Dobson, M. C. and Ulaby, F. T. and LeToan, T. and Beaudoin, A. and Kasischke, E. S. and Christensen, N.},
journal=IEEE_J_GRS,
title={Dependence of radar backscatter on coniferous forest biomass},
year={1992},
month=mar,
volume={30},
number={2},
pages={412-415},
abstract={Two independent experimental efforts have examined the dependence of radar backscatter on above-ground biomass of monospecie conifer forests using polarimetric airborne SAR data at P-, L- and C-bands. Plantations of maritime pines near Landes, France, range in age from 8 to 46 years with above-ground biomass between 5 and 105 tons/ha. Loblolly pine stands established on abandoned agricultural fields near Duke, NC, range in age from 4 to 90 years and extend the range of above-ground biomass to 560 tons/ha for the older stands. These two experimental forests are largely complementary with respect to biomass. Radar backscatter is found to increase approximately linearly with increasing biomass until it saturates at a biomass level that depends on the radar frequency. The biomass saturation level is about 200 tons/ha at P-band and 100 tons/ha at L-band, and the C-band backscattering coefficient shows much less sensitivity to total above-ground biomass},
keywords={SAR Processing, Forest, Forest parameters, biomass;C-band;Duke;France;L-band;Landes;North Carolina;P-band;SAR data;United States;age;coniferous forest biomass;maritime pines;plantations;radar backscatter;remote sensing;backscatter;ecology;forestry;remote sensing by radar;},
doi={10.1109/36.134090},
ISSN={0196-2892},
}
Keywords: SAR Processing, Simulation, SAR Simulator, Raw Data Simulator.
| Abstract: | A SAR simulator of an extended three-dimensional scene is presented. It is based on a facet model for the scene, asymptotic evaluation of SAR unit response, and a two-dimensional fast Fourier transform code for the data processing. Prescribed statistics of the model account for a realistic speckle of the image. The simulator is implemented in Synthetic Aperture Radar Advance Simulators (SARAS), whose performance is described and illustrated by a number of examples. |
@ARTICLE{FMRS92:SARAS,
author = {Giorgio Franceschetti and Maurizio Migliaccio and Daniele Riccio and Gilda Schirinzi},
title = {{SARAS: A Synthetic Aperture Radar (SAR) Raw Signal Simulator}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1992},
volume = {30},
pages = {110-123},
number = {1},
month = Jan,
abstract = {A SAR simulator of an extended three-dimensional scene is presented. It is based on a facet model for the scene, asymptotic evaluation of SAR unit response, and a two-dimensional fast Fourier transform code for the data processing. Prescribed statistics of the model account for a realistic speckle of the image. The simulator is implemented in Synthetic Aperture Radar Advance Simulators (SARAS), whose performance is described and illustrated by a number of examples.},
keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/FMRS92.pdf}
}
Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock.
| Abstract: | SAR data spatially sampled at the Nyquist limit can be correctly processed if the Doppler centroid is precisely known. Whenever the Doppler centroid shows rapid variations either with range or azimuth, more care is required in order to take advantage of the computational efficiency of frequency domain techniques. In this paper it is shown that such focusing techniques can still be exploited, provided that SAR raw data are previously modified and a space-varying nondimensional filter is applied to the focused image. The computational cost increases, but it is still smaller than time-space domain processing. Results obtained with simulated SIR-C/X-SAR data and SPOTlight geometries are presented. |
@ARTICLE{pratiRocca92:Doppler,
author = {Claudio Prati and Fabio Rocca},
title = {{Focusing SAR Data With Time-Varying Doppler Centroid}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1992},
volume = {30},
pages = {550-559},
number = {3},
month = May,
abstract = {SAR data spatially sampled at the Nyquist limit can be correctly processed if the Doppler centroid is precisely known. Whenever the Doppler centroid shows rapid variations either with range or azimuth, more care is required in order to take advantage of the computational efficiency of frequency domain techniques. In this paper it is shown that such focusing techniques can still be exploited, provided that SAR raw data are previously modified and a space-varying nondimensional filter is applied to the focused image. The computational cost increases, but it is still smaller than time-space domain processing. Results obtained with simulated SIR-C/X-SAR data and SPOTlight geometries are presented.},
keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/pratiRocca92.pdf}
}
Keywords: SAR Processing, Chirp Scaling, Extended Chirp Scaling, ECS.
| Abstract: | A new imaging algorithm is presented for Synthetic Aperture Radar (SAR) that is exact in the sense that it is capable of producing a complex image with excellent geometrical, radiometrical and phase fidelity. No interpolations or significant approximations are required, yet the method accomplishes range curvature correction over the complete range swath. The key to the approach is a quadratic phase perturbation of the range linearly frequency modulated signals while in the range signal, azimuth frequency transform (Doppler) domain. Range curvature correction is completed by a phase multiply in the two-dimensional frequency domain. Other operations required are relatively conventional. The method is generalizable to imaging geometries encountered in squint and spotlight SAR, inverse SAR, seismics, sonar, and tomography. |
@ARTICLE{raney92:ChirpScaling,
author = {Raney, R. Keith},
title = {An exact wide field digital imaging algorithm},
journal = {International Journal of Remote Sensing},
year = {1992},
volume = {13},
pages = {991-998},
month = mar,
abstract = {A new imaging algorithm is presented for Synthetic Aperture Radar (SAR) that is exact in the sense that it is capable of producing a complex image with excellent geometrical, radiometrical and phase fidelity. No interpolations or significant approximations are required, yet the method accomplishes range curvature correction over the complete range swath. The key to the approach is a quadratic phase perturbation of the range linearly frequency modulated signals while in the range signal, azimuth frequency transform (Doppler) domain. Range curvature correction is completed by a phase multiply in the two-dimensional frequency domain. Other operations required are relatively conventional. The method is generalizable to imaging geometries encountered in squint and spotlight SAR, inverse SAR, seismics, sonar, and tomography.},
keywords = {SAR Processing, Chirp Scaling, Extended Chirp Scaling, ECS},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/raney92.pdf},
url = {http://www.informaworld.com/smpp/content~db=all~content=a777329067}
}
Keywords: SAR Processing, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm.
| Abstract: | A system model and its corresponding inversion for synthetic aperture radar (SAR) imaging are presented. The system model incorporates the spherical nature of a radar's radiation pattern at far field. The inverse method based on this model performs a spatial Fourier transform (Doppler processing) on the recorded signals with respect to the available coordinates of a translational radar (SAR) or target (inverse SAR). It is shown that the transformed data provide samples of the spatial Fourier transform of the target's reflectivity function. The inverse method can be modified to incorporate deviations of the radar's motion from its prescribed straight line path. The effects of finite aperture on resolution, reconstruction, and sampling constraints for the imaging problem are discussed. |
@ARTICLE{soumekh92:Process,
author = {Mehrdad Soumekh},
title = {{A System Model and Inversion for Synthetic Aperture Radar Imaging}},
journal = {IEEE Transactions on Image Processing},
year = {1992},
volume = {1},
pages = {64-76},
number = {1},
month = Jan,
abstract = {A system model and its corresponding inversion for synthetic aperture radar (SAR) imaging are presented. The system model incorporates the spherical nature of a radar's radiation pattern at far field. The inverse method based on this model performs a spatial Fourier transform (Doppler processing) on the recorded signals with respect to the available coordinates of a translational radar (SAR) or target (inverse SAR). It is shown that the transformed data provide samples of the spatial Fourier transform of the target's reflectivity function. The inverse method can be modified to incorporate deviations of the radar's motion from its prescribed straight line path. The effects of finite aperture on resolution, reconstruction, and sampling constraints for the imaging problem are discussed.},
keywords = {SAR Processing, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm},
pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/soumekh92.pdf},
url = {http://ieeexplore.ieee.org/iel4/83/3590/00128031.pdf}
}
Conference articles
-
Ian G. Cumming,
Frank Wong,
and R. Keith Raney.
A SAR Processing Algorithm With No Interpolation.
In IGARSS '92, International Geoscience and Remote Sensing Symposium,
pages 376-379,
May 1992.
Keywords: SAR Processing, Differential Range Deramp - Frequency Domain Algorithm, DRD-FD Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Comparison of Algorithms.Abstract: Current SAR processing algorithms incorporate interpolators to perform key functions. It turns out that the interpolators are difficult to implement, and are one of the largest sources of error in the processing. In this paper, we introduce a new algorithm which eliminates the use of the interpolation operation, yet achieves accurate range migration correction over the full range swath. The algorithm can handle large apertures and large squints, and has noticeably better phase and geometry accuracy than current algorithms, even when the apertures and squints are high. The new algorithm is called Differential Range Deramp - Frequency Domain (DRD-FD) Algorithm, because its key operation is to use the linear-FM property of the range chirp to differentially shift the range energy as a function of azimuth frequency, and then to do the remaining range cell migration correction in the two-dimensional frequency domain. In this paper, the new algorithm is described, and simulation results are given to demonstrate its focusing, phase and geometric performance with squinted SAR data. In addition, an image is shown made from SEASAT data. @INPROCEEDINGS{CummWongRaney92:Processing, author = {Ian G. Cumming and Frank Wong and R. Keith Raney}, title = {{A SAR Processing Algorithm With No Interpolation}}, booktitle = {IGARSS '92, International Geoscience and Remote Sensing Symposium}, year = {1992}, pages = {376-379}, month = May, abstract = {Current SAR processing algorithms incorporate interpolators to perform key functions. It turns out that the interpolators are difficult to implement, and are one of the largest sources of error in the processing. In this paper, we introduce a new algorithm which eliminates the use of the interpolation operation, yet achieves accurate range migration correction over the full range swath. The algorithm can handle large apertures and large squints, and has noticeably better phase and geometry accuracy than current algorithms, even when the apertures and squints are high. The new algorithm is called Differential Range Deramp - Frequency Domain (DRD-FD) Algorithm, because its key operation is to use the linear-FM property of the range chirp to differentially shift the range energy as a function of azimuth frequency, and then to do the remaining range cell migration correction in the two-dimensional frequency domain. In this paper, the new algorithm is described, and simulation results are given to demonstrate its focusing, phase and geometric performance with squinted SAR data. In addition, an image is shown made from SEASAT data.}, keywords = {SAR Processing, Differential Range Deramp - Frequency Domain Algorithm, DRD-FD Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Comparison of Algorithms}, pdf = {http://www.geo.uzh.ch/~ofrey/SARbibliography/CummWongRaney92.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576716.pdf} } -
Didier Dendal and Jean L. Marchand.
Omega-k Techniques Advantages and Weaker Aspects.
In IGARSS '92, International Geoscience and Remote Sensing Symposium,
pages 366-368,
May 1992.
Keywords: SAR Processing, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Comparison of Algorithms.Abstract: Wave equation techniques and the omega-k algorithm are very attractive for future SAR space missions with on board reconstruction. The aim of the present work is to point out the stronger advantages and the weaker aspects of this algorithm compared to current SAR processors. Theoretical assumptions and approximations, practical limitations and drawbacks of the method will be outlined in contradistinction to its more positive aspects. A sensitivity analysis, with some positive conclusions, has also been performed. It will appear that there is no great revolution with regard to the traditional algorithms and that the major problems and chief restrictions are always the same, as well as the unavoidable antagonism between processing speed and reconstruction precision, even if some secondary effects are more easily handled there. @INPROCEEDINGS{DendalMarchand92:Processing, author = {Didier Dendal and Jean L. Marchand}, title = {{Omega-k Techniques Advantages and Weaker Aspects}}, booktitle = {IGARSS '92, International Geoscience and Remote Sensing Symposium}, year = {1992}, pages = {366-368}, month = May, abstract = {Wave equation techniques and the omega-k algorithm are very attractive for future SAR space missions with on board reconstruction. The aim of the present work is to point out the stronger advantages and the weaker aspects of this algorithm compared to current SAR processors. Theoretical assumptions and approximations, practical limitations and drawbacks of the method will be outlined in contradistinction to its more positive aspects. A sensitivity analysis, with some positive conclusions, has also been performed. It will appear that there is no great revolution with regard to the traditional algorithms and that the major problems and chief restrictions are always the same, as well as the unavoidable antagonism between processing speed and reconstruction precision, even if some secondary effects are more easily handled there.}, keywords = {SAR Processing, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Comparison of Algorithms}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/DendalMarchand92.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576713.pdf} } -
P.H. Eichel,
D.C. Ghiglia,
C.V. Jakowatz,
and D.E. Wahl.
Phase Gradient Autofocus for SAR Phase Correction: Explanation and Demonstration of Algorithmic Steps.
In Digital Signal Processing workshop, 1992. The,
pages 6.6.1--6.6.2,
September 13-16, 1992.
Keywords: SAR Processing, Autofocus, Phase Gradient Autofocus.@INPROCEEDINGS{Eichel1992, author = {Eichel, P.H. and Ghiglia, D.C. and Jakowatz, C.V. and Wahl, D.E.}, title = {Phase Gradient Autofocus for SAR Phase Correction: Explanation and Demonstration of Algorithmic Steps}, booktitle = {Digital Signal Processing workshop, 1992. The}, year = {1992}, pages = {6.6.1--6.6.2}, month = {September 13-16,}, keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus}, owner = {ofrey} } -
Ralf Horn and Erich Meier.
A Refined Procedure To Generate Calibrated Imagery From Airborne Synthetic Aperture Radar Data.
In Geoscience and Remote Sensing Symposium, 1992. IGARSS '92. International,
pages 406--408,
1992.
Keywords: SAR Processing, AGC, Automatic Gain Control, STC, Sensitivity Time Control, Calibration, Radiometry, Radiometric Calibration, Radiometric Correction, APG, Antenna Gain Pattern, ESAR, E-SAR.Abstract: The paper desciibes a procedure realized at DLR to generate calibrated imagery from synthetic aperture radar systems installed on board of small aircrafts. It has been especially developed for the DLR experimental radar system E-SAR, which uses antennas fixed directly to the body of a DO 228 aircraft. A receiver gain control system (STC) is implemented. The correction of the STC variable receiver gain, the compensation of the translational and rotational motion errors of the aircraft and the calibration of the radar data in the SAR processor are described. First preliminary results obtained from a recent experiment in Switzerland are shown. @INPROCEEDINGS{hornMeier92:STC, author = {Horn, Ralf and Meier, Erich}, title = {A Refined Procedure To Generate Calibrated Imagery From Airborne Synthetic Aperture Radar Data}, booktitle = {Geoscience and Remote Sensing Symposium, 1992. IGARSS '92. International}, year = {1992}, pages = {406--408}, abstract = {The paper desciibes a procedure realized at DLR to generate calibrated imagery from synthetic aperture radar systems installed on board of small aircrafts. It has been especially developed for the DLR experimental radar system E-SAR, which uses antennas fixed directly to the body of a DO 228 aircraft. A receiver gain control system (STC) is implemented. The correction of the STC variable receiver gain, the compensation of the translational and rotational motion errors of the aircraft and the calibration of the radar data in the SAR processor are described. First preliminary results obtained from a recent experiment in Switzerland are shown.}, keywords = {SAR Processing, AGC, Automatic Gain Control, STC, Sensitivity Time Control, Calibration, Radiometry, Radiometric Calibration,Radiometric Correction, APG, Antenna Gain Pattern, ESAR, E-SAR}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/hornMeier92.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576724.pdf} } -
Alberto Moreira,
Artur Brodscholl,
Jacob Dom,
Frank Kochsiek,
and Winfried Poetzsch.
Airborne Real-time SAR Processing Activities at DLR.
In Geoscience and Remote Sensing Symposium, 1992. IGARSS '92. International,
pages 412--414,
1992.
Keywords: SAR Processing, Real-Time SAR Processing, Subaperture Processing, Real-Time Subaperture Processing, Hardware Processor, STC, Sensitivity Time Control.@INPROCEEDINGS{moreiraBrodschollDomKochsiekPotzsch92:realTimeSARProc, author = {Moreira, Alberto and Brodscholl, Artur and Dom, Jacob and Kochsiek, Frank and Poetzsch, Winfried}, title = {Airborne Real-time SAR Processing Activities at DLR}, booktitle = {Geoscience and Remote Sensing Symposium, 1992. IGARSS '92. International}, year = {1992}, pages = {412--414}, keywords = {SAR Processing, Real-Time SAR Processing, Subaperture Processing, Real-Time Subaperture Processing, Hardware Processor, STC, Sensitivity Time Control}, owner = {ofrey}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/moreiraBrodschollDomKochsiekPotzsch92.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576726.pdf} } -
R. Keith Raney.
A New and Fundamental Fourier Transform Pair.
In IGARSS '92, International Geoscience and Remote Sensing Symposium,
volume 1,
pages 106-107,
1992.
Keywords: SAR Processing, Wavenumber Domain Algorithm, omega-k, Wavenumber Domain Algorithm, Stationary Phase Method, Closed Form Fourier Transform.Abstract: A closed form Fourier transform relationship between the range signal, azimuth signal domain and the range signal, azimuth frequency (or Doppler) domain is presented. The derivation assumes the presence of a large time-bandwidth pulse modulation in range. The expression is valid over a wide angular field of view, and expressed using the hyperbolic range equation. The resulting Fourier transform pair is of general utility in SAR, tomography, active seismics and related imaging problems, and allows more insight into the imaging process in the presence of range curvature than is normally available. @INPROCEEDINGS{raney:fourier, author = {R. Keith Raney}, title = {{A New and Fundamental Fourier Transform Pair}}, booktitle = {IGARSS '92, International Geoscience and Remote Sensing Symposium}, year = {1992}, volume = {1}, pages = {106-107}, abstract = {A closed form Fourier transform relationship between the range signal, azimuth signal domain and the range signal, azimuth frequency (or Doppler) domain is presented. The derivation assumes the presence of a large time-bandwidth pulse modulation in range. The expression is valid over a wide angular field of view, and expressed using the hyperbolic range equation. The resulting Fourier transform pair is of general utility in SAR, tomography, active seismics and related imaging problems, and allows more insight into the imaging process in the presence of range curvature than is normally available.}, keywords = {SAR Processing, Wavenumber Domain Algorithm, omega-k, Wavenumber Domain Algorithm, Stationary Phase Method, Closed Form Fourier Transform}, pdf = {http://www.geo.uzh.ch/~ofrey/protected/PAPERS/raney.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576640.pdf} } -
Hartmut Runge and Richard Bamler.
A Novel High Precision SAR Focussing Algorithm Based On Chirp Scaling.
In IGARSS '92, International Geoscience and Remote Sensing Symposium,
pages 372 - 375,
May 1992.
Keywords: SAR Processing, Chirp Scaling Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Comparison of Algorithms, Squinted SAR.Abstract: Azimuth compression of synthetic aperture radar data is an inherently two-dimensional problem because the SAR reference function migrates through several range resolution cells. This effect is referred to as range cell migration. For perfect focusing of the image the fact has to be accounted for that the amount of range cell migration varies with range. In classical range-Doppler SAR processors as well as with two-dimensional frequency domain processors a space-variant interpolation is required in order to compensate for this effect. In general, interpolation will degrade the final image quality and is computation time consuming. The proposed new algorithm avoids any interpolation step. It is essential for the algorithm that the SAR data are transformed to the range-Doppler domain prior to range compression. In this domain each range line is premultiplied with a particular phase function which is designed to perfectly straighten the range cell migration trajectories even for arbitrarily wide swath by the subsequent range compression step. This new method for range migration correction is the key element of a new SAR processing algorithm described in detail. The proposed method is inherently phase preserving. Its focusing quality is neither limited by high squint nor by wide swath. The implementation is simple because only multiplications and Fourier transforms are required. The paper presents a detailed derivation of the algorithm theory and illustrates possible implementations. @INPROCEEDINGS{RungeBamler92:Processing, author = {Hartmut Runge and Richard Bamler}, title = {{A Novel High Precision SAR Focussing Algorithm Based On Chirp Scaling}}, booktitle = {IGARSS '92, International Geoscience and Remote Sensing Symposium}, year = {1992}, pages = {372 - 375}, month = May, abstract = {Azimuth compression of synthetic aperture radar data is an inherently two-dimensional problem because the SAR reference function migrates through several range resolution cells. This effect is referred to as range cell migration. For perfect focusing of the image the fact has to be accounted for that the amount of range cell migration varies with range. In classical range-Doppler SAR processors as well as with two-dimensional frequency domain processors a space-variant interpolation is required in order to compensate for this effect. In general, interpolation will degrade the final image quality and is computation time consuming. The proposed new algorithm avoids any interpolation step. It is essential for the algorithm that the SAR data are transformed to the range-Doppler domain prior to range compression. In this domain each range line is premultiplied with a particular phase function which is designed to perfectly straighten the range cell migration trajectories even for arbitrarily wide swath by the subsequent range compression step. This new method for range migration correction is the key element of a new SAR processing algorithm described in detail. The proposed method is inherently phase preserving. Its focusing quality is neither limited by high squint nor by wide swath. The implementation is simple because only multiplications and Fourier transforms are required. The paper presents a detailed derivation of the algorithm theory and illustrates possible implementations.}, comment = {++}, keywords = {SAR Processing, Chirp Scaling Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Comparison of Algorithms, Squinted SAR}, pdf = {http://www.geo.uzh.ch/~ofrey/SARbibliography/RungeBamler92.pdf}, url = {http://ieeexplore.ieee.org/iel2/1014/12510/00576715.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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