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## Publications of year 2006

### Books and proceedings

1. Bert M. Kampes. Radar interferometry: persistent scatterer technique. Springer, 2006. Keyword(s): SAR Processing, SAR, Interferometry, InSAR, DInsAR, Persistent Scatterer Technique, PSI, IPTA, Interferometric Point Target Analysis.
@Book{kampesBookPSIInSAR,
title = {Radar interferometry: persistent scatterer technique},
publisher = {Springer},
year = {2006},
author = {Kampes, Bert M.},
keywords = {SAR Processing, SAR, Interferometry, InSAR, DInsAR, Persistent Scatterer Technique, PSI, IPTA, Interferometric Point Target Analysis},
owner = {ofrey},
pdf = {../kampesBookPSIInSAR.pdf},

}


2. Jian Li, Petre Stoica, Zhisong Wang, Robert G. Lorenz, Stephen P. Boyd, Alex B. Gershman, Zhi-Quan Luo, Shahram Shahbazpanahi, Xavier Mestre, Miguel A. Lagunas, Yonina C. Eldar, Arye Nehorai, Alle-Jan van der Veen, Amir Leshem, Elio D. Di Claudio, and Raffaele Parisi. Robust Adaptive Beamforming. Wiley-Interscience, 2006. Keyword(s): SAR Processing, Beamforming, Adaptive Beamforming, Robust Adaptive Beamforming, MUSIC, Capon, Subspace Methods, SAR Tomography, Tomography.
@Book{bookRABLiStoicaEditors2006:Beamforming,
Author = {Jian Li and Petre Stoica and Zhisong Wang and Robert G. Lorenz and Stephen P. Boyd and Alex B. Gershman and Zhi-Quan Luo and Shahram Shahbazpanahi and Xavier Mestre and Miguel A. Lagunas and Yonina C. Eldar and Arye Nehorai and Alle-Jan van der Veen and Amir Leshem and Elio D. Di Claudio and Raffaele Parisi},
Editor = {Li, Jian and Stoica, Petre},
Publisher = {Wiley-Interscience},
Year = {2006},
Keywords = {SAR Processing, Beamforming, Adaptive Beamforming, Robust Adaptive Beamforming, MUSIC, Capon, Subspace Methods, SAR Tomography, Tomography},
Owner = {ofrey},
Pdf = {../../../docs/bookRABLiStoicaEditors2006.pdf}
}


3. Christian Matzler. Thermal microwave radiation: applications for remote sensing, volume 52. Iet, 2006.
@Book{Maetzler2006,
author = {Matzler, Christian},
title = {Thermal microwave radiation: applications for remote sensing},
year = {2006},
volume = {52},
publisher = {Iet},
owner = {ofrey},

}


### Thesis

1. Adriano Meta. Signal Processing of FMCW Synthetic Aperture Radar Data. PhD thesis, TU Delft, 2006. Keyword(s): SAR Processing, FMCW, Frequency Modulated Continuous Wave, LFM-CW, SAR, Synthetic Aperture Radar, FMCW SAR, Airborne SAR, Focusing.

@PhdThesis{metaAdriano2006PhDThesisFMCWSARProcessing,
title = {Signal Processing of {FMCW} Synthetic Aperture Radar Data},
school = {TU Delft},
year = {2006},

Research motivation

Research objectives

Following from the motivations previously discussed, the first main objective of the project was to develop special processing SAR algorithms which could take into account the peculiar characteristics of an FMCW sensor. The features of major interest were: the presence of frequency non-linearities in the transmitted waveform and the fact that the FMCW sensor is continuously transmitting. The non-linearities represent a difference between an ideal and actual system, while the continuous motion has to be faced even when using sensors with performance close to the ideal. In the literature, some non-linearity correction algorithms were available, however they work only for very limited range intervals and, furthermore, require a reference point in each interval. For larger distance applications, as in the case for SAR, the use of these algorithms is not efficient neither robust. In FMCW SAR, the fact that the radar is continuously transmitting while moving means that the stop-and-go approximation used for the derivation of conventional SAR algorithms could not be anymore valid. These aspects needed to be analyzed and solutions had to be provided. The continuous transmission, on the other hand, can be used as an advantage in different other applications, as Moving Target Indication (MTI). In fact, in FMCW sensors, the pulse duration is considerably longer than in pulse radars, and therefore a better range frequency resolution is possible. The combination of this property and the possibility of using different kind of modulations (linear and non-linear) was investigated to see whether some FMCW SAR properties could be used to enhance the indication of moving targets. The other main objective of the project was to show the practicability of FMCW SAR under operational circumstances. Therefore, concurrently with the signal processing algorithms elaboration, the development of a fully operational airborne demonstrator system and an X-band radar front-end was started at the Delft University of Technology. A complete and detailed sensor model was required in order to estimate and analyze the performances of the system during the operational mode. In addition, the demonstrator system had to prove that an FMCW SAR sensor can indeed be operated in an efficient and cost effective manner from a very small airborne platform. The work for the initial requirements to the FMCW SAR system, the acquisition design and the development of the controlling software has been done by dr.ir. J.J.M. de Wit within the framework of the project [5]. This part will not be treated in this thesis.

Novelties and main results

Corresponding to the objectives set by the research project, the following novelties and main results have been reached and are presented in this thesis: - Non-linearity correction. The author has developed a very innovative processing solution, which completely solves the problem of the presence of frequency non-linearities in FMCW SAR. It corrects for the non-linearity effects for the whole range profile in one step, and it allows perfect range focusing, independently of the looking angle. The proposed method operates directly on the deramped data and it is very computationally efficient (Chapter 3, Section 3.4). - Deramping technique for non-linear Stepped Frequency Continuous Wave (SFCW) signals. An extension to non-linear continuous signals of the deramping technique, commonly used in linear FMCW sensors, has been developed. With the proposed extension, the great reduction in terms of sampling requirements can be achieved also when using non-linear waveforms, at the cost of increased computation (Chapter 3, Section 3.6.1). - A complete FMCW SAR signal model. The author has derived a detailed analytical model for the FMCW SAR signal in the two-dimensional frequency domain. Based on this model, proper algorithms are developed which guarantee the best performances when processing FMCW SAR data (Chapter 4). - MTI with slope diversity in linear FMCW SAR. The author has exploited the possibility of using triangular modulation for MTI by producing two images, respectively with the upslope and downslope part of the transmitted waveform. Based on the FMCW SAR signal model, interferometric techniques on the pair of images can be used to help distinguishing moving targets from stationary clutter (Chapter 5, Section 5.3). - MTI with randomized SFCW SAR. Based on the non-linear deramping technique previously proposed, the author has analyzed how randomized non-linear SFCW SAR can be used for MTI purposes (Chapter 5, Section 5.4). - Detailed system model. A complete model description of the X-band FMCW SAR front-end system developed at the IRCTR, Delft University of Technology, has been provided. The system has been extensively tested by the author together with P. Hakkart andW.F. van der Zwan through ground and laboratory measurements, the results showing very good consistency with the developed model (Chapter 6). - First demonstration of an X-band FMCW SAR. A flight test campaign has been organized during the last part of 2005. The results were very successful. The feasibility of an operational cheap FMCW SAR under practical circumstances has been proved. - High resolution FMCW SAR images. Thanks to the special algorithms developed, FMCW SAR images with 45 cm times 25 cm resolution (including windowing) have been obtained for the first time.

Outline of the thesis

The remaining of this thesis is divided in seven chapters: in the first four, the theory of FMCW SAR is introduced. Subsequently, the experimental system built at the IRCTR is described; the methods previously developed are validated by processing real FMCW SAR data collected during the flight test campaign organized in the last part of 2005. The thesis is organized as follows: Chapter 2 provides a short overview of the FMCW radar and SAR principles. It introduces aspects which are then more deeply analyzed and discussed in the subsequent chapters. Chapter 3 deals with the range processing of FMCW data and presents a novel processing solution, which completely solves the frequency non-linearity problem. It corrects for the non-linearity effects for the whole range profile and Doppler spectrum in one step, it operates directly on the deramped data and it is very computationally efficient. Nonlinear SFCW modulation is also treated in the chapter; a novel deramping technique extended to the case of non-linear signals is introduced. With the extended deramping technique proposed here, a reduced sampling frequency as for the linear case can be used also for randomized SFCW signals, at the cost of increased computation. Chapter 4 derives a complete analytical model of the FMCW SAR signal description in the two-dimensional frequency domain, starting from the deramped signal and without using the stop-and-go approximation. The model is then applied to stripmap, spotlight and single transmitter/multiple receiver Digital Beam Forming (DBF) synthetic aperture operational modes. Specially in the last two cases, the effects of the motion during the transmission and reception of the pulse can become seriously degrading for the SAR image quality, if not compensated. Chapter 5 exploits the peculiar characteristics of the complex FMCW SAR image for Moving Target Indication purposes. Two MTI methods are proposed in the chapter. The first is based on the frequency slope diversity in the transmitted modulation by using linear triangular FMCW SAR. The second makes use of the Doppler filtering properties of randomized SFCW modulations. Chapter 6 describes the X-band radar front-end developed at the Delft University of Technology. A detailed system model is provided in order to estimate and analyze the performance of the demonstrator system. Laboratory and ground based measurements show very good consistency with the calculated values, validating the model description. Chapter 7 presents the results obtained from the FMCW SAR flight test campaign organized during the last part of 2005. Thanks to the special algorithms which have been developed during the research project and described in the previous chapters, FMCW SAR images with a measured resolution up to 45 cm times 25 cm (including windowing) were obtained for the first time. Several tests performed during the flight campaign (imaging at different resolutions, varying the incident angle, MTI experiment) are reported and discussed. Chapter 8 summarizes the main results of the study which have led to this thesis; additionally, it draws conclusions and gives some recommendations for future work. Finally, as a demonstration of the increasing interest in FMCW SAR from the scientific and industry community, the chapter reports some related works started at other institutes.},
keywords = {SAR Processing, FMCW, Frequency Modulated Continuous Wave,LFM-CW, SAR, Synthetic Aperture Radar, FMCW SAR, Airborne SAR, Focusing},
owner = {ofrey},
url = {http://repository.tudelft.nl/assets/uuid:24352ff9-c11a-46c9-87d4-4d9d8968ed81/its_meta_20061002.pdf},

}


### Articles in journal or book chapters

1. Thomas L. Ainsworth, Laurent Ferro-Famil, and Jong-Sen Lee. Orientation angle preserving a posteriori polarimetric SAR calibration. IEEE Trans. Geosci. Remote Sens., 44(4):994-1003, April 2006. Keyword(s): SAR Processing, Polarimetry, Polarimetric Calibration, calibration, radar polarimetrybackscatter, calibration, covariance matrices, geophysical techniques, radar polarimetry, remote sensing by radar, synthetic aperture radar, SAR data analysis, a posteriori polarimetric SAR calibration, anechoic chamber data, orientation angle, polarimetric channels, polarimetric covariance matrix, polarimetric distortion, polarimetric fidelity, polarimetric synthetic aperture radar, radar polarimetry, scattering reciprocity, Calibration, Costs, Covariance matrix, Data analysis, Equations, Parameter estimation, Polarimetric synthetic aperture radar, Radar scattering, Soil moisture, Synthetic aperture radar, Calibration, radar polarimetry.
 Abstract: Fully polarimetric synthetic aperture radar (SAR) data analysis has found wide application for terrain classification, land-use, soil moisture, and ground cover classification. Critical to all analyses and applications is accurate calibration of the relative amplitudes of and phases between the various polarimetric channels. Here we propose an a posteriori method imposing only the weakest of constraints, scattering reciprocity, on the polarimetric data. Calibration parameters are self-consistently estimated from full 4x4 polarimetric covariance matrices. Whilst the complete set of calibration parameters is underdetermined, we give several reasonable heuristic methods to provide a complete calibration. Stronger constraints reduce the number of independent parameters and provide an overdetermined set of equations but at a cost - the loss of polarimetric fidelity when the underlying assumptions are violated. Without recourse to in situ calibration targets, the extent of the polarimetric distortion that results from polarimetric calibration remains unknown. We apply our new method to simulated data, anechoic chamber data and polarimetric SAR imagery. We also present comparisons with alternate calibration methods and different approximate solutions of the new technique.

@Article{ainsworthFerroFamilLeeTGRS2006PolCalibration,
author = {Thomas L. Ainsworth and Laurent Ferro-Famil and Jong-Sen Lee},
title = {Orientation angle preserving a posteriori polarimetric {SAR} calibration},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {4},
pages = {994-1003},
month = apr,
issn = {0196-2892},
abstract = {Fully polarimetric synthetic aperture radar (SAR) data analysis has found wide application for terrain classification, land-use, soil moisture, and ground cover classification. Critical to all analyses and applications is accurate calibration of the relative amplitudes of and phases between the various polarimetric channels. Here we propose an a posteriori method imposing only the weakest of constraints, scattering reciprocity, on the polarimetric data. Calibration parameters are self-consistently estimated from full 4x4 polarimetric covariance matrices. Whilst the complete set of calibration parameters is underdetermined, we give several reasonable heuristic methods to provide a complete calibration. Stronger constraints reduce the number of independent parameters and provide an overdetermined set of equations but at a cost - the loss of polarimetric fidelity when the underlying assumptions are violated. Without recourse to in situ calibration targets, the extent of the polarimetric distortion that results from polarimetric calibration remains unknown. We apply our new method to simulated data, anechoic chamber data and polarimetric SAR imagery. We also present comparisons with alternate calibration methods and different approximate solutions of the new technique.},
doi = {10.1109/TGRS.2005.862508},
file = {:ainsworthFerroFamilLeeTGRS2006PolCalibration.pdf:PDF},
pdf = {../../../docs/ainsworthFerroFamilLeeTGRS2006PolCalibration.pdf},

}


2. Noa B. D. Bechor and Howard A. Zebker. Measuring two-dimensional movements using a single InSAR pair. Geophysical Research Letters, 33(16):L16311 (1-5), 2006. Keyword(s): SAR Processing, ionospheric techniques, radar interferometry, synthetic aperture radar, azimuth shift, interferometric SAR ionosphere correction, ionospheric geometric distortion, Interferometry, Ionosphere, L-band, Synthetic aperture radar.
 Abstract: We present a new method to extract along-track displacements from InSAR data, based on split-beam InSAR processing, to create forward- and backward-looking interferograms. The phase difference between the two modified interferograms provides the along-track displacement component. Thus, from each conventional InSAR pair we extract two components of the displacement vector: one along the line of sight, the other in the along-track direction. We analyze the precision of the new method by comparing our solution to GPS and offset-derived along-track displacements in interferograms of the 1999, Hector Mine earthquake. The RMS error between GPS displacements and our results ranges from 5 to 8.8cm. Our method is consistent with along-track displacements derived by pixel-offsets, which are limited to 12-15 cm precision. The theoretical precision of the new method depends on SNR and coherence. For a signal to noise ratio of 30 the expected precisions are 3, 11 cm for coherence of 0.8, 0.4, respectively.

@Article{bechorZebkerGRL2006MeasuringMovementsUsingASingleInSARPair,
author = {Bechor, Noa B. D. and Zebker, Howard A.},
journal = {Geophysical Research Letters},
title = {Measuring two-dimensional movements using a single {InSAR} pair},
year = {2006},
number = {16},
pages = {L16311 (1-5)},
volume = {33},
abstract = {We present a new method to extract along-track displacements from InSAR data, based on split-beam InSAR processing, to create forward- and backward-looking interferograms. The phase difference between the two modified interferograms provides the along-track displacement component. Thus, from each conventional InSAR pair we extract two components of the displacement vector: one along the line of sight, the other in the along-track direction. We analyze the precision of the new method by comparing our solution to GPS and offset-derived along-track displacements in interferograms of the 1999, Hector Mine earthquake. The RMS error between GPS displacements and our results ranges from 5 to 8.8cm. Our method is consistent with along-track displacements derived by pixel-offsets, which are limited to 12-15 cm precision. The theoretical precision of the new method depends on SNR and coherence. For a signal to noise ratio of 30 the expected precisions are 3, 11 cm for coherence of 0.8, 0.4, respectively.},
doi = {10.1029/2006GL026883},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2006GL026883},
file = {:bechorZebkerGRL2006MeasuringMovementsUsingASingleInSARPair.pdf:PDF},
keywords = {SAR Processing, ionospheric techniques, radar interferometry, synthetic aperture radar,azimuth shift, interferometric SAR ionosphere correction, ionospheric geometric distortion, Interferometry, Ionosphere, L-band, Synthetic aperture radar},
owner = {ofrey},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2006GL026883},

}


3. Karl-Heinz Bethke, S. Baumgartner, M. Gabele, D. Hounam, E. Kemptner, D. Klement, G. Krieger, and R. Erxleben. Air- and spaceborne monitoring of road traffic using SAR moving target indication--Project TRAMRAD. ISPRS Journal of Photogrammetry and Remote Sensing, Theme Issue: Airborne and Spaceborne Traffic Monitoring, 61(3-4):243-259, December 2006. Keyword(s): SAR Processing, TRAMRAD, Traffic Monitoring, TerraSAR-X, STAP, Space-Time Adaptive Processing, MTI, Moving Target Indication, SAR Interferometry, Interferometry, ATI, Along-Track SAR Interferometry.

@Article{bethkeBaumgartnerGabeleHounamKemptnerKlementKriegerErxleben:TRAMRAD,
Title = {Air- and spaceborne monitoring of road traffic using SAR moving target indication--Project TRAMRAD},
Author = {Karl-Heinz Bethke and S. Baumgartner and M. Gabele and D. Hounam and E. Kemptner and D. Klement and G. Krieger and R. Erxleben},
Month = {dec},
Number = {3-4},
Pages = {243--259},
Volume = {61},
Year = {2006},
Journal = {ISPRS Journal of Photogrammetry and Remote Sensing, Theme Issue: Airborne and Spaceborne Traffic Monitoring},
Keywords = {SAR Processing, TRAMRAD, Traffic Monitoring, TerraSAR-X, STAP, Space-Time Adaptive Processing, MTI, Moving Target Indication,SAR Interferometry, Interferometry, ATI, Along-Track SAR Interferometry},
Owner = {ofrey},
Pdf = {../../../docs/bethkeBaumgartnerGabeleHounamKemptnerKlementKriegerErxleben.pdf}
}


4. E.J. Candes, J. Romberg, and T. Tao. Robust uncertainty principles: exact signal reconstruction from highly incomplete frequency information. IEEE Transactions on Information Theory, 52(2):489-509, feb. 2006. Keyword(s): Fourier coefficient, convex optimization, discrete-time signal, image reconstruction, incomplete frequency information, linear programming, minimization problem, nonlinear sampling theorem, piecewise constant object, probability value, robust uncertainty principle, signal reconstruction, sparse random matrix, trigonometric expansion, Fourier analysis, convex programming, image reconstruction, image sampling, indeterminancy, linear programming, minimisation, piecewise constant techniques, probability, signal reconstruction, signal sampling, sparse matrices;.
 Abstract: This paper considers the model problem of reconstructing an object from incomplete frequency samples. Consider a discrete-time signal f isin;CN and a randomly chosen set of frequencies Omega;. Is it possible to reconstruct f from the partial knowledge of its Fourier coefficients on the set Omega;? A typical result of this paper is as follows. Suppose that f is a superposition of |T| spikes f(t)= sigma; tau; isin;Tf( tau;) delta;(t- tau;) obeying |T| le;CM middot;(log N)-1 middot; | Omega;| for some constant CM>0. We do not know the locations of the spikes nor their amplitudes. Then with probability at least 1-O(N-M), f can be reconstructed exactly as the solution to the #8467;1 minimization problem. In short, exact recovery may be obtained by solving a convex optimization problem. We give numerical values for CM which depend on the desired probability of success. Our result may be interpreted as a novel kind of nonlinear sampling theorem. In effect, it says that any signal made out of |T| spikes may be recovered by convex programming from almost every set of frequencies of size O(|T| middot;logN). Moreover, this is nearly optimal in the sense that any method succeeding with probability 1-O(N-M) would in general require a number of frequency samples at least proportional to |T| middot;logN. The methodology extends to a variety of other situations and higher dimensions. For example, we show how one can reconstruct a piecewise constant (one- or two-dimensional) object from incomplete frequency samples - provided that the number of jumps (discontinuities) obeys the condition above - by minimizing other convex functionals such as the total variation of f.

@Article{1580791,
author = {Candes, E.J. and Romberg, J. and Tao, T.},
journal = {IEEE Transactions on Information Theory},
title = {Robust uncertainty principles: exact signal reconstruction from highly incomplete frequency information},
year = {2006},
issn = {0018-9448},
month = {feb.},
number = {2},
pages = {489-509},
volume = {52},
abstract = {This paper considers the model problem of reconstructing an object from incomplete frequency samples. Consider a discrete-time signal f isin;CN and a randomly chosen set of frequencies Omega;. Is it possible to reconstruct f from the partial knowledge of its Fourier coefficients on the set Omega;? A typical result of this paper is as follows. Suppose that f is a superposition of |T| spikes f(t)= sigma; tau; isin;Tf( tau;) delta;(t- tau;) obeying |T| le;CM middot;(log N)-1 middot; | Omega;| for some constant CM>0. We do not know the locations of the spikes nor their amplitudes. Then with probability at least 1-O(N-M), f can be reconstructed exactly as the solution to the #8467;1 minimization problem. In short, exact recovery may be obtained by solving a convex optimization problem. We give numerical values for CM which depend on the desired probability of success. Our result may be interpreted as a novel kind of nonlinear sampling theorem. In effect, it says that any signal made out of |T| spikes may be recovered by convex programming from almost every set of frequencies of size O(|T| middot;logN). Moreover, this is nearly optimal in the sense that any method succeeding with probability 1-O(N-M) would in general require a number of frequency samples at least proportional to |T| middot;logN. The methodology extends to a variety of other situations and higher dimensions. For example, we show how one can reconstruct a piecewise constant (one- or two-dimensional) object from incomplete frequency samples - provided that the number of jumps (discontinuities) obeys the condition above - by minimizing other convex functionals such as the total variation of f.},
doi = {10.1109/TIT.2005.862083},
keywords = {Fourier coefficient; convex optimization; discrete-time signal; image reconstruction; incomplete frequency information; linear programming; minimization problem; nonlinear sampling theorem; piecewise constant object; probability value; robust uncertainty principle; signal reconstruction; sparse random matrix; trigonometric expansion; Fourier analysis; convex programming; image reconstruction; image sampling; indeterminancy; linear programming; minimisation; piecewise constant techniques; probability; signal reconstruction; signal sampling; sparse matrices;},

}


5. Emmanuel J. Candes, Justin K. Romberg, and Terence Tao. Stable signal recovery from incomplete and inaccurate measurements. Communications on Pure and Applied Mathematics, 59(8):1207-1223, 2006. Keyword(s): Compressive Sensing, Compressed Sensing.
 Abstract: Suppose we wish to recover a vector x0 element of R (e.g., a digital signal or image) from incomplete and contaminated observations y = A x0 + e; A is an n times m matrix with far fewer rows than columns (n << m) and e is an error term. Is it possible to recover x0 accurately based on the data y? To recover x0, we consider the solution x# to the L1-regularization problem $${\rm \min}\; |x\|_{\ell_1} \quad {\rm subject \; to } \; \|Ax-y\|_{\ell_2} \leq \epsilon,$$ where epsilon is the size of the error term e. We show that if A obeys a uniform uncertainty principle (with unit-normed columns) and if the vector x0 is sufficiently sparse, then the solution is within the noise level $$\|x^\sharp - x_0\|_{\ell_2} \leq C \cdot \epsilon.$$ As a first example, suppose that A is a Gaussian random matrix; then stable recovery occurs for almost all such A's provided that the number of nonzeros of x0 is of about the same order as the number of observations. As a second instance, suppose one observes few Fourier samples of x0; then stable recovery occurs for almost any set of n coefficients provided that the number of nonzeros is of the order of n/(log m)^6. In the case where the error term vanishes, the recovery is of course exact, and this work actually provides novel insights into the exact recovery phenomenon discussed in earlier papers. The methodology also explains why one can also very nearly recover approximately sparse signals.

@Article{CPA:CPA20124,
Title = {Stable signal recovery from incomplete and inaccurate measurements},
Author = {Candes, Emmanuel J. and Romberg, Justin K. and Tao, Terence},
Doi = {10.1002/cpa.20124},
ISSN = {1097-0312},
Number = {8},
Pages = {1207-1223},
Url = {http://dx.doi.org/10.1002/cpa.20124},
Volume = {59},
Year = {2006},
Abstract = {Suppose we wish to recover a vector x0 element of R (e.g., a digital signal or image) from incomplete and contaminated observations y = A x0 + e; A is an n times m matrix with far fewer rows than columns (n << m) and e is an error term. Is it possible to recover x0 accurately based on the data y? To recover x0, we consider the solution x# to the L1-regularization problem $${\rm \min}\; |x\|_{\ell_1} \quad {\rm subject \; to } \; \|Ax-y\|_{\ell_2} \leq \epsilon,$$ where epsilon is the size of the error term e. We show that if A obeys a uniform uncertainty principle (with unit-normed columns) and if the vector x0 is sufficiently sparse, then the solution is within the noise level $$\|x^\sharp - x_0\|_{\ell_2} \leq C \cdot \epsilon.$$ As a first example, suppose that A is a Gaussian random matrix; then stable recovery occurs for almost all such A's provided that the number of nonzeros of x0 is of about the same order as the number of observations. As a second instance, suppose one observes few Fourier samples of x0; then stable recovery occurs for almost any set of n coefficients provided that the number of nonzeros is of the order of n/(log m)^6. In the case where the error term vanishes, the recovery is of course exact, and this work actually provides novel insights into the exact recovery phenomenon discussed in earlier papers. The methodology also explains why one can also very nearly recover approximately sparse signals.},
Journal = {Communications on Pure and Applied Mathematics},
Keywords = {Compressive Sensing, Compressed Sensing},
Publisher = {Wiley Subscription Services, Inc., A Wiley Company}
}


 Abstract: The bandwidth of RAMSES, an airborne synthetic aperture radar (SAR) system was recently increased to 1.2 GHz in X- and Ku-bands, yielding (unweighted) 3 dB range resolution of 11 cm. The synthesis of SAR images with matching cross-range resolution requires long integration times, and this disqualifies the temporal-domain back-projection synthesis algorithm as impractically slow. The wider relative bandwidth also disqualifies simplified range/Doppler types of algorithms, as the hypothesis of proportionality between Doppler and squint is no longer valid. Therefore the authors implemented a fast-frequency domain synthesis algorithm (\u03a9-k or range-migration algorithm) and designed a new deterministic motion and antenna pattern compensation method for it. As the required accuracy on carrier trajectory exceeded the performance of the differential GPS-hybridised inertial navigation unit, the authors implemented an autofocus based on the phase-tracking of several isotropic point-like echoes.

@Article{cantalloubeDuboisFernandez:OneraHighResXBand,
Title = {Airborne X-band SAR imaging with 10 cm resolution: technical challenge and preliminary results},
Author = {Cantalloube, Hubert-M.J. and Pascale Dubois-Fernandez},
Doi = {10.1049/ip-rsn:20045097},
ISSN = {1350-2395},
Month = {apr},
Number = {2},
Pages = {163--176},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1626085&isnumber=34128},
Volume = {153},
Year = {2006},
Abstract = {The bandwidth of RAMSES, an airborne synthetic aperture radar (SAR) system was recently increased to 1.2 GHz in X- and Ku-bands, yielding (unweighted) 3 dB range resolution of 11 cm. The synthesis of SAR images with matching cross-range resolution requires long integration times, and this disqualifies the temporal-domain back-projection synthesis algorithm as impractically slow. The wider relative bandwidth also disqualifies simplified range/Doppler types of algorithms, as the hypothesis of proportionality between Doppler and squint is no longer valid. Therefore the authors implemented a fast-frequency domain synthesis algorithm (\u03a9-k or range-migration algorithm) and designed a new deterministic motion and antenna pattern compensation method for it. As the required accuracy on carrier trajectory exceeded the performance of the differential GPS-hybridised inertial navigation unit, the authors implemented an autofocus based on the phase-tracking of several isotropic point-like echoes.},
Keywords = {SAR Processing, Doppler radar, airborne radar, antenna radiation patterns, frequency-domain synthesis, image resolution, microwave antennas, radar antennas, radar cross-sections, radar imaging, radar resolution, radar tracking, synthetic aperture radar, 1.2 GHz, Ku-band, RAMSES, bandwidth, X-band, Airborne SAR, antenna pattern compensation, carrier trajectory, cross-range resolution, deterministic motion, fast-frequency domain synthesis, isotropic point-like echo, phase-tracking, Autofocus, Residual Motion Errors, Motion Compensation, MoComp, Time-Domain Back-Projection, TDBP, temporal-domain back-projection synthesis},
Owner = {ofrey},
Pdf = {../../../docs/}
}


7. Shane R. Cloude. Polarization coherence tomography. Radio Sci., 41, August 2006. Keyword(s): SAR Processing, SAR Tomography, radar tomography, polarimetric interferometry, radar polarimetry, Remote sensing, Inverse scattering, Random media and rough surfaces, Interferometry, InSAR, SAR Interferometry, PolInSAR.
 Abstract: In this paper we introduce a new radar-imaging technique, called polarization coherence tomography (PCT), which employs variation of the interferometric coherence with polarization to reconstruct a vertical profile function in penetrable volume scattering. We first show how this profile function can be efficiently represented as a Fourier-Legendre series, with tomographic reconstruction reducing to estimation of the unknown coefficients of this series from coherence data. We then show that we can linearize this inversion by using a priori knowledge of two parameters, namely, volume depth and topographic phase. We further propose a new algorithm based on polarimetric interferometry to estimate these two from the data itself. To assess stability, we investigate both the single- and dual-baseline conditioning of the associated matrix inversion and then concentrate on the single-baseline case to demonstrate that for sufficient multilooking (around 50), stable retrievals of profiles can be obtained in the presence of coherence noise. Finally, we apply the technique to simulated L band coherent radar data to demonstrate its potential for new applications in radar remote sensing.

@Article{Cloude2006,
Title = {Polarization coherence tomography},
Author = {Cloude, Shane R.},
Doi = {http://dx.doi.org/10.1029/2005RS003436},
Month = aug,
Url = {http://europa.agu.org/?view=article&uri=/journals/rs/rs0604/2005RS003436/2005RS003436.xml},
Volume = {41},
Year = {2006},
Abstract = {In this paper we introduce a new radar-imaging technique, called polarization coherence tomography (PCT), which employs variation of the interferometric coherence with polarization to reconstruct a vertical profile function in penetrable volume scattering. We first show how this profile function can be efficiently represented as a Fourier-Legendre series, with tomographic reconstruction reducing to estimation of the unknown coefficients of this series from coherence data. We then show that we can linearize this inversion by using a priori knowledge of two parameters, namely, volume depth and topographic phase. We further propose a new algorithm based on polarimetric interferometry to estimate these two from the data itself. To assess stability, we investigate both the single- and dual-baseline conditioning of the associated matrix inversion and then concentrate on the single-baseline case to demonstrate that for sufficient multilooking (around 50), stable retrievals of profiles can be obtained in the presence of coherence noise. Finally, we apply the technique to simulated L band coherent radar data to demonstrate its potential for new applications in radar remote sensing.},
Keywords = {SAR Processing, SAR Tomography, radar tomography, polarimetric interferometry, radar polarimetry, Remote sensing, Inverse scattering, Random media and rough surfaces, Interferometry, InSAR, SAR Interferometry, PolInSAR},
Owner = {ofrey},
Pdf = {../../../docs/cloude2006PolarimetricCoherenceTomography.pdf},
Publisher = {American Geophysical Union}
}


8. E. Colin, C. Titin-Schnaider, and W. Tabbara. An interferometric coherence optimization method in radar polarimetry for high-resolution imagery. IEEE Trans. Geosci. Remote Sens., 44(1):167-175, January 2006. Keyword(s): X-band interferometric SAR image, X-band polarimetric SAR image, anechoic chamber, data acquisition, high-resolution imagery, interferometric coherence optimization, point scatterer separation, radar polarimetry, single-mechanism coherence, synthetic aperture radar, target measurements, backscatter, data acquisition, geophysical signal processing, geophysical techniques, radar imaging, radar polarimetry, radiowave interferometry, remote sensing by radar, synthetic aperture radar;.
 Abstract: This paper investigates to what extent a new interferometric coherence optimization in radar polarimetry allows the separation of point scatterers located in the same resolution cell according to their interferometric phases. An interferometric coherence definition called the single-mechanism coherence is introduced, and the corresponding optimization method is briefly discussed. This method was first validated theoretically when no volume decorrelation occurs. Then, it has been applied to simple target measurements acquired in an anechoic chamber, and to an X-band polarimetric and interferometric synthetic aperture radar image containing man-made targets. In both cases, the single-mechanism coherence optimization enables to resolve the interferometric phases of several scattering centers inside the same resolution cell.

@Article{colinTitinSchnaiderTabbara2006,
author = {Colin, E. and Titin-Schnaider, C. and Tabbara, W.},
journal = {IEEE Trans. Geosci. Remote Sens.},
title = {An interferometric coherence optimization method in radar polarimetry for high-resolution imagery},
year = {2006},
issn = {0196-2892},
month = jan,
number = {1},
pages = {167-175},
volume = {44},
abstract = {This paper investigates to what extent a new interferometric coherence optimization in radar polarimetry allows the separation of point scatterers located in the same resolution cell according to their interferometric phases. An interferometric coherence definition called the single-mechanism coherence is introduced, and the corresponding optimization method is briefly discussed. This method was first validated theoretically when no volume decorrelation occurs. Then, it has been applied to simple target measurements acquired in an anechoic chamber, and to an X-band polarimetric and interferometric synthetic aperture radar image containing man-made targets. In both cases, the single-mechanism coherence optimization enables to resolve the interferometric phases of several scattering centers inside the same resolution cell.},
doi = {10.1109/TGRS.2005.859357},
keywords = {X-band interferometric SAR image; X-band polarimetric SAR image; anechoic chamber; data acquisition; high-resolution imagery; interferometric coherence optimization; point scatterer separation; radar polarimetry; single-mechanism coherence; synthetic aperture radar; target measurements; backscatter; data acquisition; geophysical signal processing; geophysical techniques; radar imaging; radar polarimetry; radiowave interferometry; remote sensing by radar; synthetic aperture radar;},

}


 Abstract: This paper investigates to what extent a new interferometric coherence optimization in radar polarimetry allows the separation of point scatterers located in the same resolution cell according to their interferometric phases. An interferometric coherence definition called the single-mechanism coherence is introduced, and the corresponding optimization method is briefly discussed. This method was first validated theoretically when no volume decorrelation occurs. Then, it has been applied to simple target measurements acquired in an anechoic chamber, and to an X-band polarimetric and interferometric synthetic aperture radar image containing man-made targets. In both cases, the single-mechanism coherence optimization enables to resolve the interferometric phases of several scattering centers inside the same resolution cell.

@Article{colinTitinSchnaiderTabbaraTGRS2006InSARCoherenceOptimization,
author = {E. Colin and C. Titin-Schnaider and W. Tabbara},
title = {An interferometric coherence optimization method in radar polarimetry for high-resolution imagery},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {1},
pages = {167-175},
month = jan,
issn = {0196-2892},
abstract = {This paper investigates to what extent a new interferometric coherence optimization in radar polarimetry allows the separation of point scatterers located in the same resolution cell according to their interferometric phases. An interferometric coherence definition called the single-mechanism coherence is introduced, and the corresponding optimization method is briefly discussed. This method was first validated theoretically when no volume decorrelation occurs. Then, it has been applied to simple target measurements acquired in an anechoic chamber, and to an X-band polarimetric and interferometric synthetic aperture radar image containing man-made targets. In both cases, the single-mechanism coherence optimization enables to resolve the interferometric phases of several scattering centers inside the same resolution cell.},
doi = {10.1109/TGRS.2005.859357},
owner = {ofrey},

}


10. Ian G. Cumming and Shu Li. Improved slope estimation for SAR Doppler ambiguity resolution. IEEE Trans. Geosci. Remote Sens., 44(3):707-718, 2006. Keyword(s): SAR Processing, Doppler Centroid Estimation, Doppler radar, Radon transforms, radar resolution, remote sensing by radar, synthetic aperture radar, Doppler Ambiguity Resolver, DAR, Radon transform, SAR, antenna pointing angle, look displacement algorithm, satellite beam pointing angle, slope estimation.
 Abstract: The idea of using the Radon transform to measure the alignment of linear features in synthetic aperture radar (SAR) data has breathed new life into the look displacement class of Doppler ambiguity resolution algorithms. In these algorithms, the slope of target energy is estimated to obtain the satellite beam pointing angle accurately enough to resolve the Doppler ambiguity. After explaining the method and adding some minor improvements, it is shown how it can work well on satellite SAR data. Then, an alternate method is developed that combines the ideas of the Radon and look displacement algorithms to obtain a computationally simpler and more accurate algorithm. In addition, the quality checks of the spatial diversity approach are used to increase the robustness of the algorithm. Even though the algorithm was conceived for high-contrast scenes, it works remarkably well in low to medium contrast scenes as well.

@Article{cummingLi2006:DopcenRadon,
Title = {Improved slope estimation for SAR Doppler ambiguity resolution},
Author = {Cumming, Ian G. and Li, Shu},
ISSN = {0196-2892},
Number = {3},
Pages = {707--718},
Url = {http://ieeexplore.ieee.org/iel5/36/33599/01597475.pdf},
Volume = {44},
Year = {2006},
Abstract = {The idea of using the Radon transform to measure the alignment of linear features in synthetic aperture radar (SAR) data has breathed new life into the look displacement class of Doppler ambiguity resolution algorithms. In these algorithms, the slope of target energy is estimated to obtain the satellite beam pointing angle accurately enough to resolve the Doppler ambiguity. After explaining the method and adding some minor improvements, it is shown how it can work well on satellite SAR data. Then, an alternate method is developed that combines the ideas of the Radon and look displacement algorithms to obtain a computationally simpler and more accurate algorithm. In addition, the quality checks of the spatial diversity approach are used to increase the robustness of the algorithm. Even though the algorithm was conceived for high-contrast scenes, it works remarkably well in low to medium contrast scenes as well.},
Journal = {IEEE Trans. Geosci. Remote Sens.},
Keywords = {SAR Processing, Doppler Centroid Estimation, Doppler radar, Radon transforms, radar resolution, remote sensing by radar, synthetic aperture radar, Doppler Ambiguity Resolver, DAR, Radon transform, SAR, antenna pointing angle, look displacement algorithm, satellite beam pointing angle, slope estimation},
Owner = {ofrey},
Pdf = {../../../docs/cummingLi2006.pdf},
Timestamp = {2006.05.02}
}


11. Francesco De Zan and Andrea Monti Guarnieri. TOPSAR: Terrain Observation by Progressive Scans. IEEE Trans. Geosci. Remote Sens., 44(9):2352-2360, Sept 2006. Keyword(s): array signal processing, remote sensing by radar, synthetic aperture radar, terrain mapping, SPOT, TOPSAR, azimuth-varying ambiguities, focusing technique, radar beam, scalloping ambiguities, scanning synthetic aperture radar, terrain observation with progressive scan, Azimuth, Focusing, Frequency, Geometry, Interferometry, Low earth orbit satellites, Polarization, Radar antennas, Radar signal processing, Spaceborne radar, Array signal processing, interferometry, scanning antennas, synthetic aperture radar (SAR).
 Abstract: In this paper, a novel (according to the authors' knowledge) type of scanning synthetic aperture radar (ScanSAR) that solves the problems of scalloping and azimuth-varying ambiguities is introduced. The technique employs a very simple counterrotation of the radar beam in the opposite direction to a SPOT: hence, the name terrain observation with progressive scan (TOPS). After a short summary of the characteristics of the ScanSAR technique and its problems, TOPSAR, which is the technique of design, the limits, and a focusing technique are introduced. A synthetic example based on a possible future system follows

@Article{deZanMontiGuarnieriTGARS2006TOPS,
author = {De Zan, Francesco and Monti Guarnieri, Andrea},
title = {{TOPSAR}: Terrain Observation by Progressive Scans},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {9},
pages = {2352-2360},
month = {Sept},
issn = {0196-2892},
abstract = {In this paper, a novel (according to the authors' knowledge) type of scanning synthetic aperture radar (ScanSAR) that solves the problems of scalloping and azimuth-varying ambiguities is introduced. The technique employs a very simple counterrotation of the radar beam in the opposite direction to a SPOT: hence, the name terrain observation with progressive scan (TOPS). After a short summary of the characteristics of the ScanSAR technique and its problems, TOPSAR, which is the technique of design, the limits, and a focusing technique are introduced. A synthetic example based on a possible future system follows},
doi = {10.1109/TGRS.2006.873853},
file = {:deZanMontiGuarnieriTGARS2006TOPS.pdf:PDF},
pdf = {../../../docs/deZanMontiGuarnieriTGARS2006TOPS.pdf},

}


12. P. M. L. Drezet and S. Quegan. Environmental effects on the interferometric repeat-pass coherence of forests. IEEE_J_GRS, 44(4):825-837, April 2006. Keyword(s): backscatter, dielectric properties, forestry, radiowave interferometry, remote sensing by radar, synthetic aperture radar, vegetation mapping, C-band one-day tandem coherence measurement, SAR, dielectric backscattering coefficient, environmental effects, forest canopy coherence, interferometric repeat-pass coherence, moisture conditions, moisture fluctuations, soil moisture, soil-vegetation-atmosphere transfer model, synthetic aperature radar, vegetation, wind conditions, Backscatter, Coherence, Coupled mode analysis, Dielectric measurements, Fluctuations, Moisture measurement, Predictive models, Satellites, Soil measurements, Wind, Coherence, dielectric, dynamic, forest, multitemporal, synthetic aperature radar (SAR), vegetation.
@Article{Drezet2006,
author = {P. M. L. Drezet and S. Quegan},
title = {Environmental effects on the interferometric repeat-pass coherence of forests},
year = {2006},
volume = {44},
number = {4},
month = apr,
pages = {825--837},
issn = {0196-2892},
doi = {10.1109/TGRS.2006.864387},
journal = IEEE_J_GRS,
keywords = {backscatter, dielectric properties, forestry, radiowave interferometry, remote sensing by radar, synthetic aperture radar, vegetation mapping, C-band one-day tandem coherence measurement, SAR, dielectric backscattering coefficient, environmental effects, forest canopy coherence, interferometric repeat-pass coherence, moisture conditions, moisture fluctuations, soil moisture, soil-vegetation-atmosphere transfer model, synthetic aperature radar, vegetation, wind conditions, Backscatter, Coherence, Coupled mode analysis, Dielectric measurements, Fluctuations, Moisture measurement, Predictive models, Satellites, Soil measurements, Wind, Coherence, dielectric, dynamic, forest, multitemporal, synthetic aperature radar (SAR), vegetation},
owner = {ofrey},

}


13. C. Elachi, S. Wall, M. Janssen, E. Stofan, R. Lopes, R. Kirk, R. Lorenz, J. Lunine, F. Paganelli, L. Soderblom, C. Wood, L. Wye, H. Zebker, Y. Anderson, S. Ostro, M. Allison, R. Boehmer, P. Callahan, P. Encrenaz, E. Flamini, G. Francescetti, Y. Gim, G. Hamilton, S. Hensley, W. Johnson, K. Kelleher, D. Muhleman, G. Picardi, F. Posa, L. Roth, R. Seu, S. Shaffer, B. Stiles, S. Vetrella, and R. West. Titan Radar Mapper observations from Cassini's T3 fly-by. Nature, 441(7094):709-713, June 2006.
@Article{elachiEtAlNature2006CassiniRadarTitanMapper,
author = {Elachi, C. and Wall, S. and Janssen, M. and Stofan, E. and Lopes, R. and Kirk, R. and Lorenz, R. and Lunine, J. and Paganelli, F. and Soderblom, L. and Wood, C. and Wye, L. and Zebker, H. and Anderson, Y. and Ostro, S. and Allison, M. and Boehmer, R. and Callahan, P. and Encrenaz, P. and Flamini, E. and Francescetti, G. and Gim, Y. and Hamilton, G. and Hensley, S. and Johnson, W. and Kelleher, K. and Muhleman, D. and Picardi, G. and Posa, F. and Roth, L. and Seu, R. and Shaffer, S. and Stiles, B. and Vetrella, S. and West, R.},
title = {Titan Radar Mapper observations from Cassini's T3 fly-by},
journal = {Nature},
year = {2006},
volume = {441},
number = {7094},
pages = {709-713},
month = jun,
issn = {0028-0836},
comment = {10.1038/nature04786},
owner = {ofrey},
url = {http://dx.doi.org/10.1038/nature04786},

}


14. Qianqian Fang, P.M. Meaney, and K.D. Paulsen. The Multidimensional Phase Unwrapping Integral and Applications to Microwave Tomographical Image Reconstruction. IEEE Transactions on Image Processing, 15(11):3311-3324, November 2006. Keyword(s): SAR Processing, SAR Tomography, Tomography, Gauss-Newton iterative microwave image reconstruction, MRI, closed path integral, dynamic phase unwrapping, iteratively modified property distributions, microwave tomographical image reconstruction, multidimensional phase unwrapping integral, optical confocal microscopy, phase singularities, singularity location, spatial unwrapping, synthetic aperture radar interferometry, time varying electromagnetic fields, Newton method, computerised tomography, electromagnetic fields, image reconstruction, medical image processing;.
 Abstract: Spatial unwrapping of the phase component of time varying electromagnetic fields has important implications in a range of disciplines including synthetic aperture radar (SAR) interferometry, MRI, optical confocal microscopy, and microwave tomography. This paper presents a fundamental framework based on the phase unwrapping integral, especially in the complex case where phase singularities are enclosed within the closed path integral. With respect to the phase unwrapping required when utilized in Gauss-Newton iterative microwave image reconstruction, the concept of dynamic phase unwrapping is introduced where the singularity location varies as a function of the iteratively modified property distributions. Strategies for dynamic phase unwrapping in the microwave problem were developed and successfully tested in simulations and clinical experiments utilizing large, high contrast targets to validate the approach

@Article{1709977,
Title = {The Multidimensional Phase Unwrapping Integral and Applications to Microwave Tomographical Image Reconstruction},
Author = {Qianqian Fang and Meaney, P.M. and Paulsen, K.D.},
Doi = {10.1109/TIP.2006.881999},
ISSN = {1057-7149},
Month = nov,
Number = {11},
Pages = {3311-3324},
Volume = {15},
Year = {2006},
Abstract = {Spatial unwrapping of the phase component of time varying electromagnetic fields has important implications in a range of disciplines including synthetic aperture radar (SAR) interferometry, MRI, optical confocal microscopy, and microwave tomography. This paper presents a fundamental framework based on the phase unwrapping integral, especially in the complex case where phase singularities are enclosed within the closed path integral. With respect to the phase unwrapping required when utilized in Gauss-Newton iterative microwave image reconstruction, the concept of dynamic phase unwrapping is introduced where the singularity location varies as a function of the iteratively modified property distributions. Strategies for dynamic phase unwrapping in the microwave problem were developed and successfully tested in simulations and clinical experiments utilizing large, high contrast targets to validate the approach},
Journal = {IEEE Transactions on Image Processing},
Keywords = {SAR Processing, SAR Tomography, Tomography, Gauss-Newton iterative microwave image reconstruction;MRI;closed path integral;dynamic phase unwrapping;iteratively modified property distributions;microwave tomographical image reconstruction;multidimensional phase unwrapping integral;optical confocal microscopy;phase singularities;singularity location;spatial unwrapping;synthetic aperture radar interferometry;time varying electromagnetic fields;Newton method;computerised tomography;electromagnetic fields;image reconstruction;medical image processing;}
}


 Abstract: In this letter, a practical mean reflectivity model of radar land clutter (LC) for the complex system design of ground-based radars involved in low-angle targets on some typical terrains is studied using the inductive reasoning method. The functional relationships between the radar parameters and radar surface clutter backscattering are analyzed. Following the recent research work in the area of reflectivity modeling of LC in the literature, the least squares method is employed to estimate the model parameters. The model is validated using reliable practical data and shown to outperform other models in accuracy.

@Article{fengChenGRSL2006LowAngleLandClutterModelling,
author = {S. Feng and J. Chen},
title = {Low-angle reflectivity modeling of land clutter},
journal = {IEEE Geoscience and Remote Sensing Letters},
year = {2006},
volume = {3},
number = {2},
month = apr,
pages = {254-258},
issn = {1545-598X},
doi = {10.1109/LGRS.2005.863847},
abstract = {In this letter, a practical mean reflectivity model of radar land clutter (LC) for the complex system design of ground-based radars involved in low-angle targets on some typical terrains is studied using the inductive reasoning method. The functional relationships between the radar parameters and radar surface clutter backscattering are analyzed. Following the recent research work in the area of reflectivity modeling of LC in the literature, the least squares method is employed to estimate the model parameters. The model is validated using reliable practical data and shown to outperform other models in accuracy.},
owner = {ofrey},

}


16. G. Fornaro, G. Franceschetti, and S. Perna. On center-beam approximation in SAR motion compensation. IEEE Geoscience and Remote Sensing Letters, 3(2):276 - 280, april 2006. Keyword(s): airborne SAR, airborne raw data focusing, center beam approximation, geometrical analysis, motion compensation, synthetic aperture radar, airborne radar, motion compensation, remote sensing by radar, synthetic aperture radar.
 Abstract: This work provides a geometrical analysis to assess the effects of center-beam approximation, crucial for efficient airborne raw data focusing, on the final image.

@Article{fornaroFranceschettiPernaGRSL2006BeamCenterApproxInMoComp,
author = {Fornaro, G. and Franceschetti, G. and Perna, S.},
journal = {IEEE Geoscience and Remote Sensing Letters},
title = {On center-beam approximation in {SAR} motion compensation},
year = {2006},
issn = {1545-598X},
month = {april},
number = {2},
pages = {276 - 280},
volume = {3},
abstract = {This work provides a geometrical analysis to assess the effects of center-beam approximation, crucial for efficient airborne raw data focusing, on the final image.},
doi = {10.1109/LGRS.2005.863391},
file = {:fornaroFranceschettiPernaGRSL2006BeamCenterApproxInMoComp.pdf:PDF},
keywords = {airborne SAR; airborne raw data focusing; center beam approximation; geometrical analysis; motion compensation; synthetic aperture radar; airborne radar; motion compensation; remote sensing by radar; synthetic aperture radar},

}


17. G. Fornaro, A. Monti Guarnieri, A. Pauciullo, and Francesco De-Zan. Maximum likelihood multi-baseline SAR interferometry. IEE Proceedings - Radar, Sonar and Navigation, 153(3):279-288, June 2006. Keyword(s): SAR Processing, InSAR, Interferometry.
 Abstract: A technique to provide interferometry by combining multiple images of the same area is proposed. This technique exploits all the images jointly and performs an optimal spectral shift pre- processing to remove most of the decorrelation for distributed targets. Its applications are mainly for DEM generation at centimetric accuracy, and for differential interferometry. The major requirement is that targets are coherent over all the images: this may be the case for current multi-pass over desert areas, or better for the case of images coming from future short revisit time systems (constellations, cart-wheel, geosynchronous SAR etc.).

@Article{fornaroMontiGuarnieriPauciulloDeZanIEERSN2005MaxLieklihoodMultiBaselineSARInterferometry,
author = {Fornaro, G. and Monti Guarnieri, A. and Pauciullo, A. and De-Zan, Francesco},
title = {Maximum likelihood multi-baseline {SAR} interferometry},
year = {2006},
volume = {153},
number = {3},
pages = {279-288},
month = jun,
issn = {1350-2395},
abstract = {A technique to provide interferometry by combining multiple images of the same area is proposed. This technique exploits all the images jointly and performs an optimal spectral shift pre- processing to remove most of the decorrelation for distributed targets. Its applications are mainly for DEM generation at centimetric accuracy, and for differential interferometry. The major requirement is that targets are coherent over all the images: this may be the case for current multi-pass over desert areas, or better for the case of images coming from future short revisit time systems (constellations, cart-wheel, geosynchronous SAR etc.).},
keywords = {SAR Processing, InSAR, Interferometry},
url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01648547},

}


18. G. Fornaro and F. Serafino. Imaging of Single and Double Scatterers in Urban Areas via SAR Tomography. IEEE Trans. Geosci. Remote Sens., 44(12):3497-3505, 2006. Keyword(s): SAR Processing, SAR Tomography, Tomography, geophysical techniques, remote sensing by radar, synthetic aperture radar, tomography, topography (Earth), 3D synthetic aperture radar tomography, European Remote Sensing 1 satellite, European Remote Sensing 2 satellite, Italy, Naples, Napoli, SAR sensors, data calibration, microwave scattering, residual topography, spatial-differencing technique, surface deformation, urban areas, Multibaseline coherent synthetic aperture radar (SAR) processing, SAR tomography, three-dimensional (3-D) SAR focusing.
 Abstract: Microwave scattering is a rather complex mechanism, especially in urban areas. Three-dimensional (3-D) synthetic aperture radar (SAR) tomography is a technique that uses multiple views to map the scattering power at different heights, thus extending the capability of SAR sensors to fully image the scene in the 3-D space. This paper presents a first validation of spaceborne long-term SAR tomography by demonstrating the capability to resolve a simple layover case, i.e., to separate single- and double-scattering mechanisms within imaged pixels. Results obtained with real data acquired by the European Remote Sensing 1 and 2 (ERS-1 and ERS-2) satellites over the urban area of Napoli are presented. As an additional contribution, an innovative algorithm estimating residual topography and surface deformation, called the spatial-differencing technique, is also discussed in detail at the data calibration stage

@Article{fornaroSerafino06:Tomo,
Title = {Imaging of Single and Double Scatterers in Urban Areas via {SAR} Tomography},
Author = {Fornaro, G. and Serafino, F.},
ISSN = {0196-2892},
Number = {12},
Pages = {3497--3505},
Url = {http://ieeexplore.ieee.org/iel5/36/4014302/04014314.pdf},
Volume = {44},
Year = {2006},
Abstract = {Microwave scattering is a rather complex mechanism, especially in urban areas. Three-dimensional (3-D) synthetic aperture radar (SAR) tomography is a technique that uses multiple views to map the scattering power at different heights, thus extending the capability of SAR sensors to fully image the scene in the 3-D space. This paper presents a first validation of spaceborne long-term SAR tomography by demonstrating the capability to resolve a simple layover case, i.e., to separate single- and double-scattering mechanisms within imaged pixels. Results obtained with real data acquired by the European Remote Sensing 1 and 2 (ERS-1 and ERS-2) satellites over the urban area of Napoli are presented. As an additional contribution, an innovative algorithm estimating residual topography and surface deformation, called the spatial-differencing technique, is also discussed in detail at the data calibration stage},
Journal = {IEEE Trans. Geosci. Remote Sens.},
Keywords = {SAR Processing, SAR Tomography, Tomography, geophysical techniques, remote sensing by radar, synthetic aperture radar, tomography, topography (Earth), 3D synthetic aperture radar tomography, European Remote Sensing 1 satellite, European Remote Sensing 2 satellite, Italy, Naples, Napoli, SAR sensors, data calibration, microwave scattering, residual topography, spatial-differencing technique, surface deformation, urban areas, Multibaseline coherent synthetic aperture radar (SAR) processing, SAR tomography, three-dimensional (3-D) SAR focusing},
Owner = {ofrey},
Pdf = {../../../docs/fornaroSerafinoTomo06.pdf}
}


19. G. Franceschetti, A. Iodice, S. Perna, and D. Riccio. SAR Sensor Trajectory Deviations: Fourier Domain Formulation and Extended Scene Simulation of Raw Signal. IEEE Transactions on Geoscience and Remote Sensing, 44(9):2323-2334, September 2006. Keyword(s): SAR Processing, Simulation, SAR RAW Signal Simulation, Fourier transforms, geophysical signal processing, remote sensing by radar, synthetic aperture radar, 1D azimuth Fourier domain processing, 2D Fourier domain SAR raw signal simulator, Fourier domain formulation, airborne SAR systems, computation efficiency, extended scene simulation, fast Fourier transform algorithms, inversion algorithm design, mission planning, narrow beam-slow deviation assumption, nominal straight-line path, processing algorithm testing, range time-domain integration, sensor trajectory deviations, synthetic aperture radar raw signal simulation, system design, Algorithm design and analysis, Computational modeling, Fast Fourier transforms, Layout, Process planning, Signal design, Signal processing, Synthetic aperture radar, System testing, Two dimensional displays, Motion compensation, simulation, synthetic aperture radar (SAR).
 Abstract: Synthetic aperture radar (SAR) raw signal simulation is a useful tool for SAR system design, mission planning, processing algorithm testing, and inversion algorithm design. A two-dimensional (2-D) Fourier domain SAR raw signal simulator, exploiting the efficiency of fast Fourier transform algorithms, has been presented some years ago and is able to generate the raw signal corresponding to extended scenes. However, it cannot account for the effects of sensor trajectory deviations with respect to the nominal straight-line path. This paper explores the possibility of extending the efficient Fourier domain simulation approach to the case of sensor trajectory deviations, which is more realistic for airborne SAR systems. We first of all obtain a general and compact Fourier domain formulation of the SAR raw signal in the presence of arbitrary trajectory deviations, and show that in this general case no efficient simulation scheme can be devised. However, we demonstrate that, if a narrow beam and slow trajectory deviation assumption is made, a full 2-D Fourier domain simulation can be used. This approach can be applied only to some SAR systems and/or trajectory deviations, but it has the advantage that processing time is practically not increased with respect to the nominal trajectory case. The validity limits of the approach are analytically evaluated. Some simulation results are finally presented in order to verify the effectiveness of the proposed simulation scheme. In another paper, which is the second part of this work, it will be shown that the narrow beam-slow deviation assumption can be relaxed, at the expense of computation efficiency, if a one-dimensional azimuth Fourier domain processing followed by a range time-domain integration is used

@Article{franceschettiIodicePernaRiccioTGRS2006SARTrajectoryDeviationFFTSimulationOfRawSignal,
author = {G. Franceschetti and A. Iodice and S. Perna and D. Riccio},
title = {{SAR} Sensor Trajectory Deviations: Fourier Domain Formulation and Extended Scene Simulation of {Raw} Signal},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {2006},
volume = {44},
number = {9},
pages = {2323-2334},
month = sep,
issn = {0196-2892},
abstract = {Synthetic aperture radar (SAR) raw signal simulation is a useful tool for SAR system design, mission planning, processing algorithm testing, and inversion algorithm design. A two-dimensional (2-D) Fourier domain SAR raw signal simulator, exploiting the efficiency of fast Fourier transform algorithms, has been presented some years ago and is able to generate the raw signal corresponding to extended scenes. However, it cannot account for the effects of sensor trajectory deviations with respect to the nominal straight-line path. This paper explores the possibility of extending the efficient Fourier domain simulation approach to the case of sensor trajectory deviations, which is more realistic for airborne SAR systems. We first of all obtain a general and compact Fourier domain formulation of the SAR raw signal in the presence of arbitrary trajectory deviations, and show that in this general case no efficient simulation scheme can be devised. However, we demonstrate that, if a narrow beam and slow trajectory deviation assumption is made, a full 2-D Fourier domain simulation can be used. This approach can be applied only to some SAR systems and/or trajectory deviations, but it has the advantage that processing time is practically not increased with respect to the nominal trajectory case. The validity limits of the approach are analytically evaluated. Some simulation results are finally presented in order to verify the effectiveness of the proposed simulation scheme. In another paper, which is the second part of this work, it will be shown that the narrow beam-slow deviation assumption can be relaxed, at the expense of computation efficiency, if a one-dimensional azimuth Fourier domain processing followed by a range time-domain integration is used},
doi = {10.1109/TGRS.2006.873206},
file = {:franceschettiIodicePernaRiccioTGRS2006SARTrajectoryDeviationFFTSimulationOfRawSignal.pdf:PDF},
keywords = {SAR Processing, Simulation, SAR RAW Signal Simulation, Fourier transforms;geophysical signal processing;remote sensing by radar;synthetic aperture radar;1D azimuth Fourier domain processing;2D Fourier domain SAR raw signal simulator;Fourier domain formulation;airborne SAR systems;computation efficiency;extended scene simulation;fast Fourier transform algorithms;inversion algorithm design;mission planning;narrow beam-slow deviation assumption;nominal straight-line path;processing algorithm testing;range time-domain integration;sensor trajectory deviations;synthetic aperture radar raw signal simulation;system design;Algorithm design and analysis;Computational modeling;Fast Fourier transforms;Layout;Process planning;Signal design;Signal processing;Synthetic aperture radar;System testing;Two dimensional displays;Motion compensation;simulation;synthetic aperture radar (SAR)},
owner = {ofrey},
pdf = {../../../docs/franceschettiIodicePernaRiccioTGRS2006SARTrajectoryDeviationFFTSimulationOfRawSignal.pdf},

}


20. J.L. Gomez-Dans, S. Quegan, and J.C. Bennett. Indoor C-band polarimetric interferometry observations of a mature wheat canopy. IEEE Trans. Geosci. Remote Sens., 44(4):768-777, April 2006. Keyword(s): SAR Processing, SAR Tomography, Tomography, 2D scan, HH polarization, VH polarization, VV polarization, crop height retrieval, ground-based synthetic aperture radar, incidence angle, indoor C-band polarimetric interferometry observation, polarimetric coherence optimization, polarimetric tomography, polarization synthesis, unconstrained coherence optimization, vegetation monitoring, wheat canopy, crops, radar polarimetry, radiowave interferometry, remote sensing by radar, synthetic aperture radar, vegetation mapping;.
 Abstract: We present results from experiments carried out in the ground-based synthetic aperture radar (GB-SAR) facility at the University of Sheffield to ascertain the role of polarimetric interferometry in crop height retrieval. To this end, a mature wheat canopy, grown in outdoor conditions, was reassembled inside the GB-SAR chamber and imaged at C-band using a two-dimensional scan. This allowed fully polarimetric tomography and interferometry. Interferometry using the VV, HH, and VH polarization states shows that the HH and VH interferograms retrieve a height close to the top of the soil layer for all angles of incidence considered, whereas the height retrieved from the VV interferogram increases with angle of incidence. The use of a Pauli basis gives poor results, due to the different location of the scattering phase centers in the VV and HH channels. The use of arbitrary polarization states shows that the top of the soil can be very accurately estimated using left-circular polarization, whereas, for angles of incidence close to 45 deg;, a polarization state similar to VV can be used to retrieve the top of the canopy; hence crop height can be recovered as the difference of these two interferometric heights. Polarimetric coherence optimization techniques are also studied. Unconstrained coherence optimization gives very unstable results, due to the small number of available samples. Constrained optimization results in stable retrieved heights, and the retrieved polarization states agree well with the polarization synthesis results.

@Article{1610813,
Title = {Indoor C-band polarimetric interferometry observations of a mature wheat canopy},
Author = {Gomez-Dans, J.L. and Quegan, S. and Bennett, J.C.},
Doi = {10.1109/TGRS.2005.863861},
ISSN = {0196-2892},
Month = apr,
Number = {4},
Pages = {768-777},
Volume = {44},
Year = {2006},
Abstract = {We present results from experiments carried out in the ground-based synthetic aperture radar (GB-SAR) facility at the University of Sheffield to ascertain the role of polarimetric interferometry in crop height retrieval. To this end, a mature wheat canopy, grown in outdoor conditions, was reassembled inside the GB-SAR chamber and imaged at C-band using a two-dimensional scan. This allowed fully polarimetric tomography and interferometry. Interferometry using the VV, HH, and VH polarization states shows that the HH and VH interferograms retrieve a height close to the top of the soil layer for all angles of incidence considered, whereas the height retrieved from the VV interferogram increases with angle of incidence. The use of a Pauli basis gives poor results, due to the different location of the scattering phase centers in the VV and HH channels. The use of arbitrary polarization states shows that the top of the soil can be very accurately estimated using left-circular polarization, whereas, for angles of incidence close to 45 deg;, a polarization state similar to VV can be used to retrieve the top of the canopy; hence crop height can be recovered as the difference of these two interferometric heights. Polarimetric coherence optimization techniques are also studied. Unconstrained coherence optimization gives very unstable results, due to the small number of available samples. Constrained optimization results in stable retrieved heights, and the retrieved polarization states agree well with the polarization synthesis results.},
Journal = {IEEE Trans. Geosci. Remote Sens.},
Keywords = {SAR Processing, SAR Tomography, Tomography, 2D scan; HH polarization; VH polarization; VV polarization; crop height retrieval; ground-based synthetic aperture radar; incidence angle; indoor C-band polarimetric interferometry observation; polarimetric coherence optimization; polarimetric tomography; polarization synthesis; unconstrained coherence optimization; vegetation monitoring; wheat canopy; crops; radar polarimetry; radiowave interferometry; remote sensing by radar; synthetic aperture radar; vegetation mapping;}
}


21. Franz Meyer, Richard Bamler, N. Jakowski, and Thomas Fritz. The Potential of Low-Frequency SAR Systems for Mapping Ionospheric TEC Distributions. IEEE_J_GRSL, 3(4):560-564, October 2006. Keyword(s): SAR Processing, electron density, ionosphere, ionospheric techniques, microwave propagation, synthetic aperture radar, SAR signal properties, broadband L-band SAR, broadband microwave radiation, correlation technique, dispersive media, group delay, interferometric technique, ionospheric TEC distribution mapping, ionospheric propagation effects, low-frequency SAR systems, phase advance, synthetic aperture radar, total electron content, two-frequency global positioning system observations, Delay systems, Dielectrics, Dispersion, Electrons, Ionosphere, L-band, Position measurement, Refractive index, Signal mapping, Synthetic aperture radar, Atmospheric effects, L-band SAR, SAR interferometry, correlation, dispersive media, ionosphere, synthetic aperture radar (SAR), total electron content (TEC).
 Abstract: Ionospheric propagation effects have a significant impact on the signal properties of low-frequency synthetic aperture radar (SAR) systems. Range delay, interferometric phase bias, range defocusing, and Faraday rotation are the most prominent ones. All the effects are a function of the so-called total electron content (TEC). Methods based on two-frequency global positioning system observations allow measuring TEC in the ionosphere with coarse spatial resolution only. In this letter, the potential of broadband L-band SAR systems for ionospheric TEC mapping is studied. As a basis, the dispersive nature of the ionosphere and its effects on broadband microwave radiation are theoretically derived and analyzed. It is shown that phase advance and group delay can be measured by interferometric and correlation techniques, respectively. The achievable accuracy suffices in mapping small-scale ionospheric TEC disturbances. A differential TEC estimator that separates ionospheric from tropospheric contributions is proposed.

@Article{meyerBamlerJakowskiFritzGRSL2006PotentialLowFreqSARForIonoTEC,
author = {Franz Meyer and Richard Bamler and N. Jakowski and Thomas Fritz},
title = {The Potential of Low-Frequency {SAR} Systems for Mapping Ionospheric TEC Distributions},
journal = IEEE_J_GRSL,
year = {2006},
volume = {3},
number = {4},
pages = {560--564},
month = oct,
issn = {1545-598X},
abstract = {Ionospheric propagation effects have a significant impact on the signal properties of low-frequency synthetic aperture radar (SAR) systems. Range delay, interferometric phase bias, range defocusing, and Faraday rotation are the most prominent ones. All the effects are a function of the so-called total electron content (TEC). Methods based on two-frequency global positioning system observations allow measuring TEC in the ionosphere with coarse spatial resolution only. In this letter, the potential of broadband L-band SAR systems for ionospheric TEC mapping is studied. As a basis, the dispersive nature of the ionosphere and its effects on broadband microwave radiation are theoretically derived and analyzed. It is shown that phase advance and group delay can be measured by interferometric and correlation techniques, respectively. The achievable accuracy suffices in mapping small-scale ionospheric TEC disturbances. A differential TEC estimator that separates ionospheric from tropospheric contributions is proposed.},
doi = {10.1109/LGRS.2006.882148},
file = {:meyerBamlerJakowskiFritzGRSL2006PotentialLowFreqSARForIonoTEC.pdf:PDF},
keywords = {SAR Processing, electron density, ionosphere, ionospheric techniques, microwave propagation, synthetic aperture radar, SAR signal properties, broadband L-band SAR, broadband microwave radiation, correlation technique, dispersive media, group delay, interferometric technique, ionospheric TEC distribution mapping, ionospheric propagation effects, low-frequency SAR systems, phase advance, synthetic aperture radar, total electron content, two-frequency global positioning system observations, Delay systems, Dielectrics, Dispersion, Electrons, Ionosphere, L-band, Position measurement, Refractive index, Signal mapping, Synthetic aperture radar, Atmospheric effects, L-band SAR, SAR interferometry, correlation, dispersive media, ionosphere, synthetic aperture radar (SAR), total electron content (TEC)},
owner = {ofrey},

}


22. Daniele Perissin, Claudio Prati, Marcus E. Engdahl, and Y.L. Desnos. Validating the SAR Wavenumber Shift Principle With the ERS-Envisat PS Coherent Combination. IEEE Trans. Geosci. Remote Sens., 44(9):2343-2351, September 2006. Keyword(s): SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, Decorrelation, Frequency, Geometry, Interferometry, Master-slave, Radar imaging, Radar scattering, Remote sensing, Satellites, Synthetic aperture radar, data acquisition, image registration, remote sensing by radar, synthetic aperture radar, ERS-Envisat PS coherent combination, European Remote Sensing Satellite Synthetic Aperture Radar archive by means Envisat Advanced SAR data, SAR wavenumber shift principle, ground resolution cell, images coregistration step, permanent scatterers, slant-range position, spectral shift principle, subcell accuracy, Interferometry, synthetic aperture radar (SAR);.
 Abstract: Continuity of the European Remote Sensing Satellite Synthetic Aperture Radar (ERS SAR) archive by means of Envisat Advanced SAR (ASAR) data acquired from March 2002 has introduced the problem of the coherent combination of images coming from sensors with slightly different frequencies. The spectral shift principle states that in case of extended distributed targets, the frequency shift is equivalent to a change of looking angle. In this paper, the same principle is exploited to analyze the behavior of permanent scatterers (PSs) with an extension that is smaller than the ground resolution cell. The conditions under which the PSs identified by ERS can be continued by Envisat are then theoretically determined and experimentally validated. Moreover, this analysis shows that acquisitions characterized by different frequencies can be used to identify the slant-range position of scatterers with high subcell accuracy (tens of centimeters). From the processing side, a very precise images coregistration step is required to get the results described in this paper

@Article{perissinPratiEngdahlDesnosTGRS2006,
author = {Perissin, Daniele and Prati, Claudio and Engdahl, Marcus E. and Desnos, Y.L.},
title = {Validating the {SAR} Wavenumber Shift Principle With the {ERS}-{Envisat} {PS} Coherent Combination},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {9},
pages = {2343-2351},
month = sep,
issn = {0196-2892},
abstract = {Continuity of the European Remote Sensing Satellite Synthetic Aperture Radar (ERS SAR) archive by means of Envisat Advanced SAR (ASAR) data acquired from March 2002 has introduced the problem of the coherent combination of images coming from sensors with slightly different frequencies. The spectral shift principle states that in case of extended distributed targets, the frequency shift is equivalent to a change of looking angle. In this paper, the same principle is exploited to analyze the behavior of permanent scatterers (PSs) with an extension that is smaller than the ground resolution cell. The conditions under which the PSs identified by ERS can be continued by Envisat are then theoretically determined and experimentally validated. Moreover, this analysis shows that acquisitions characterized by different frequencies can be used to identify the slant-range position of scatterers with high subcell accuracy (tens of centimeters). From the processing side, a very precise images coregistration step is required to get the results described in this paper},
doi = {10.1109/TGRS.2006.875455},
file = {:perissinPratiEngdahlDesnosTGRS2006.pdf:PDF},
keywords = {SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, Decorrelation;Frequency;Geometry;Interferometry;Master-slave;Radar imaging;Radar scattering;Remote sensing;Satellites;Synthetic aperture radar;data acquisition;image registration;remote sensing by radar;synthetic aperture radar;ERS-Envisat PS coherent combination;European Remote Sensing Satellite Synthetic Aperture Radar archive by means Envisat Advanced SAR data;SAR wavenumber shift principle;ground resolution cell;images coregistration step;permanent scatterers;slant-range position;spectral shift principle;subcell accuracy;Interferometry;synthetic aperture radar (SAR);},
pdf = {../../../docs/perissinPratiEngdahlDesnosTGRS2006.pdf},

}


23. Daniele Perissin and Fabio Rocca. High-Accuracy Urban DEM Using Permanent Scatterers. IEEE Trans. Geosci. Remote Sens., 44(11):3338-3347, November 2006. Keyword(s): SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, Area measurement, Cities and towns, Decorrelation, Digital elevation models, Interferometry, Monitoring, Radar detection, Radar scattering, Synthetic aperture radar, Volcanoes, building, interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), Milan, building profile, city street level, digital elevation model, ground deformations monitoring, high-accuracy urban DEM, interferometry, permanent scatterers, slow-landslide detection, spatial density grid, subsidence, synthetic aperture radar, terrain mapping, urban elevation maps, volcano monitoring, Interferometry, synthetic aperture radar (SAR), terrain mapping, urban areas;.
 Abstract: The permanent scatterers (PS) technique is a powerful operational tool that exploits a long series of synthetic aperture radar data for monitoring ground deformations with millimeter accuracy on a high spatial density grid of pointwise targets. The technique has been applied successfully to a number of applications, from subsidence and volcano monitoring to slow-landslide detection. This paper aims to analyze and demonstrate the positioning capability of the PS technique applied to the generation of urban elevation maps. The problem of the univocal identification of the PS position (discarding pixel-dependent sidelobes, both far and near) is addressed, and an easy and efficient solution is proposed. The results obtained in the Milan site allow the appreciation of the very high quality of an urban digital elevation model retrieved with the PS technique. The ground level of the city is identified with submeter accuracy, and elevated targets, where present, reveal building profiles. The estimated city street level (ranging plusmn3m in 16times18 km2) is then compared to those obtained with the same technique using a descending parallel track and an ascending one. Furthermore, the estimated PS elevation with respect to the ground has been connected to temperature-dependent elongations of high structures

@Article{perissinRoccaTGRS2006PSI,
author = {Perissin, Daniele and Rocca, Fabio},
title = {High-Accuracy Urban {DEM} Using Permanent Scatterers},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {11},
pages = {3338-3347},
month = nov,
issn = {0196-2892},
abstract = {The permanent scatterers (PS) technique is a powerful operational tool that exploits a long series of synthetic aperture radar data for monitoring ground deformations with millimeter accuracy on a high spatial density grid of pointwise targets. The technique has been applied successfully to a number of applications, from subsidence and volcano monitoring to slow-landslide detection. This paper aims to analyze and demonstrate the positioning capability of the PS technique applied to the generation of urban elevation maps. The problem of the univocal identification of the PS position (discarding pixel-dependent sidelobes, both far and near) is addressed, and an easy and efficient solution is proposed. The results obtained in the Milan site allow the appreciation of the very high quality of an urban digital elevation model retrieved with the PS technique. The ground level of the city is identified with submeter accuracy, and elevated targets, where present, reveal building profiles. The estimated city street level (ranging plusmn3m in 16times18 km2) is then compared to those obtained with the same technique using a descending parallel track and an ascending one. Furthermore, the estimated PS elevation with respect to the ground has been connected to temperature-dependent elongations of high structures},
doi = {10.1109/TGRS.2006.877754},
file = {:perissinRoccaTGRS2006PSI.pdf:PDF},
keywords = {SAR Processing, Persistent Scatterer Interferometry, PSI, SAR Interferometry, InSAR, DInSAR, Interferometry, Area measurement;Cities and towns;Decorrelation;Digital elevation models;Interferometry;Monitoring;Radar detection;Radar scattering;Synthetic aperture radar;Volcanoes;building;interferometry;remote sensing by radar;synthetic aperture radar;terrain mapping;topography (Earth);Milan;building profile;city street level;digital elevation model;ground deformations monitoring;high-accuracy urban DEM;interferometry;permanent scatterers;slow-landslide detection;spatial density grid;subsidence;synthetic aperture radar;terrain mapping;urban elevation maps;volcano monitoring;Interferometry;synthetic aperture radar (SAR);terrain mapping;urban areas;},
pdf = {../../../docs/perissinRoccaTGRS2006PSI.pdf},

}


 Abstract: This paper proposes a unified framework for predicting optimized pairing strategies for interferometric processing of multipass synthetic aperture radar data. The approach consists in a minimum spanning tree (MST) structure based on a distance function encoding an a priori model for the interferometric quality of each image pair. Using a distance function modeled after the interferometric coherence allows reproducing many small baseline strategies presented in the recent literature. A novel application of the method to the processing steps of image coregistration and equalization is illustrated, using a test European Remote Sensing Satellite dataset. Widespread methods used for these two operations rely on the computation of the amplitude cross correlation over a large number of corresponding tie patches distributed over the scene. Geometric shift and radiometric equalization parameters are estimated over the patches and used, respectively, within a polynomial warp model and a radiometric correction scheme. The number of reliable patches available behaves similarly to the interferometric synthetic aperture radar (InSAR) coherence with respect to the baselines, and can be assimilated to a quality figure for the derivation of the MST. Results show an improvement in the quality of the stepwise (SW)-processed image stack with respect to the classical single-master procedure, confirming that the SW approach is able to provide better conditions for the estimation of correlation-related InSAR parameters.

@Article{reficeBovengaNutricato06:Tomo,
Title = {MST-based stepwise connection strategies for multipass Radar data with application to coregistration and equalization},
Author = {Refice, A. and Bovenga, F. and Nutricato, R.},
ISSN = {0196-2892},
Number = {8},
Pages = {2029--2040},
Url = {http://ieeexplore.ieee.org/iel5/36/34774/01661792.pdf},
Volume = {44},
Year = {2006},
Abstract = {This paper proposes a unified framework for predicting optimized pairing strategies for interferometric processing of multipass synthetic aperture radar data. The approach consists in a minimum spanning tree (MST) structure based on a distance function encoding an a priori model for the interferometric quality of each image pair. Using a distance function modeled after the interferometric coherence allows reproducing many small baseline strategies presented in the recent literature. A novel application of the method to the processing steps of image coregistration and equalization is illustrated, using a test European Remote Sensing Satellite dataset. Widespread methods used for these two operations rely on the computation of the amplitude cross correlation over a large number of corresponding tie patches distributed over the scene. Geometric shift and radiometric equalization parameters are estimated over the patches and used, respectively, within a polynomial warp model and a radiometric correction scheme. The number of reliable patches available behaves similarly to the interferometric synthetic aperture radar (InSAR) coherence with respect to the baselines, and can be assimilated to a quality figure for the derivation of the MST. Results show an improvement in the quality of the stepwise (SW)-processed image stack with respect to the classical single-master procedure, confirming that the SW approach is able to provide better conditions for the estimation of correlation-related InSAR parameters.},
Journal = {IEEE Trans. Geosci. Remote Sens.},
Owner = {ofrey},
Pdf = {../../../docs/reficeBovengaNutricato06Tomo.pdf}
}


25. Andreas Reigber, E. Alivizatos, A. Potsis, and Alberto Moreira. Extended wavenumber-domain synthetic aperture radar focusing with integrated motion compensation. Radar, Sonar and Navigation, IEE Proceedings, 153(3):301-310, 2006. Keyword(s): SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, EOK, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR, E-SAR, ECS, Extended Chirp Scaling.
 Abstract: Modern synthetic aperture radar (SAR) systems are continually developing in the direction of higher spatial resolution. This requires the usage of high range bandwidths combined with long azimuth integration intervals. High-quality SAR processing methods, which are able to deal with such sensor parameters, are necessary for focusing the raw data of such sensors. Wavenumber-domain (omegak) processing is commonly accepted as the ideal solution to the SAR focusing problem. However, it is only applicable to spaceborne SAR data where a straight sensor trajectory is given. In the case of airborne data, wavenumber-domain processing is limited because of its inability to perform high-precision motion compensation. Here, the extended chirp scaling (ECS) algorithm has proven to be very powerful, although it has certain limitations concerning long aperture syntheses and highly squinted geometries. In the paper, a new stripmap SAR data-processing algorithm, called extended omega-k (EOK), is analytically derived. The EOK algorithm aims to combine the high focusing accuracy of the wavenumber-domain algorithm with the high-precision motion compensation of the ECS algorithm. The new EOK algorithm integrates a three-step motion compensation correction in the general formulation of the wavenumber-domain algorithm, leading to a new airborne SAR processing scheme, which is also very robust in the cases of long synthetic apertures and high squint angles. As demonstrated, it offers the possibility of processing wide-band, low-frequency airborne SAR data up to nearwavelength resolution. The performance and accuracy of the new EOK SAR data-processing algorithm are demonstrated using simulated data in different data collection scenarios and geometries as well as using interferometric data acquired by the airborne experimental SAR system of DLR at L-band (Horn, 1996; Scheiber, 1999).

@Article{reigberAlivizatosPotsisMoreira06:EOK,
Title = {Extended wavenumber-domain synthetic aperture radar focusing with integrated motion compensation},
Author = {Reigber, Andreas and Alivizatos, E. and Potsis, A. and Moreira, Alberto},
ISSN = {1350-2395},
Number = {3},
Pages = {301--310},
Url = {http://ieeexplore.ieee.org/iel5/2198/34563/01648550.pdf},
Volume = {153},
Year = {2006},
Abstract = {Modern synthetic aperture radar (SAR) systems are continually developing in the direction of higher spatial resolution. This requires the usage of high range bandwidths combined with long azimuth integration intervals. High-quality SAR processing methods, which are able to deal with such sensor parameters, are necessary for focusing the raw data of such sensors. Wavenumber-domain (omegak) processing is commonly accepted as the ideal solution to the SAR focusing problem. However, it is only applicable to spaceborne SAR data where a straight sensor trajectory is given. In the case of airborne data, wavenumber-domain processing is limited because of its inability to perform high-precision motion compensation. Here, the extended chirp scaling (ECS) algorithm has proven to be very powerful, although it has certain limitations concerning long aperture syntheses and highly squinted geometries. In the paper, a new stripmap SAR data-processing algorithm, called extended omega-k (EOK), is analytically derived. The EOK algorithm aims to combine the high focusing accuracy of the wavenumber-domain algorithm with the high-precision motion compensation of the ECS algorithm. The new EOK algorithm integrates a three-step motion compensation correction in the general formulation of the wavenumber-domain algorithm, leading to a new airborne SAR processing scheme, which is also very robust in the cases of long synthetic apertures and high squint angles. As demonstrated, it offers the possibility of processing wide-band, low-frequency airborne SAR data up to nearwavelength resolution. The performance and accuracy of the new EOK SAR data-processing algorithm are demonstrated using simulated data in different data collection scenarios and geometries as well as using interferometric data acquired by the airborne experimental SAR system of DLR at L-band (Horn, 1996; Scheiber, 1999).},
Keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, EOK, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR, E-SAR, ECS, Extended Chirp Scaling},
Owner = {ofrey},
Pdf = {../../../docs/reigberAlivizatosPotsisMoreira06.pdf},
Timestamp = {2006.07.27}
}


26. A. Reigber, P. Prats, and J. J. Mallorqui. Refined estimation of time-varying baseline errors in airborne SAR interferometry. IEEE Geoscience and Remote Sensing Letters, 3(1):145-149, January 2006. Keyword(s): SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, Baseline refinement, calibration, interferometry, InSAR, Motion Compensation, repeat-pass interferometry, Residual Motion Errors, RME, Squinted SAR, Multi-Squint Processing, ESAR, geophysical signal processing, geophysical techniques, motion compensation, remote sensing by radar, synthetic aperture radar SAR focusing, airborne SAR data, airborne SAR interferometry, digital elevation model, motion compensation, multisquint processing approach, navigation system, repeat-pass systems, residual motion errors, synthetic aperture radar, time-varying baseline errors.
 Abstract: The processing of airborne synthetic aperture radar (SAR) data requires a precise compensation of the deviations of the platform movement from a straight line. This is usually carried out by recording the trajectory with a high-precision navigation system and correcting them during SAR focusing. However, due to the lack of accuracy in current navigation systems, residual motion errors persist in the images. Such residual motion errors are mainly noticeable in repeat-pass systems, where they are causing time-varying baseline errors, visible as artefacts in the derived phase maps. In this letter, a refined method for the estimation of time-varying baseline errors is presented. An improved multisquint processing approach is used for obtaining robust estimates of higher order baseline errors over the entire scene, even if parts of the scene are heavily decorrelated. In a subsequent step, the proposed method incorporates an external digital elevation model for detection of linear and constant components of the baseline error along azimuth. Calibration targets in the scene are not necessary.

@Article{reigberPratsMallorqui2006:RefinedBaseLineEstim,
Title = {{Refined estimation of time-varying baseline errors in airborne SAR interferometry}},
Author = {Reigber, A. and Prats, P. and Mallorqui, J. J.},
Doi = {10.1109/LGRS.2005.860482},
Month = {jan},
Number = {1},
Pages = {145-149},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1576708&isnumber=33327},
Volume = {3},
Year = {2006},
Abstract = {The processing of airborne synthetic aperture radar (SAR) data requires a precise compensation of the deviations of the platform movement from a straight line. This is usually carried out by recording the trajectory with a high-precision navigation system and correcting them during SAR focusing. However, due to the lack of accuracy in current navigation systems, residual motion errors persist in the images. Such residual motion errors are mainly noticeable in repeat-pass systems, where they are causing time-varying baseline errors, visible as artefacts in the derived phase maps. In this letter, a refined method for the estimation of time-varying baseline errors is presented. An improved multisquint processing approach is used for obtaining robust estimates of higher order baseline errors over the entire scene, even if parts of the scene are heavily decorrelated. In a subsequent step, the proposed method incorporates an external digital elevation model for detection of linear and constant components of the baseline error along azimuth. Calibration targets in the scene are not necessary.},
Journal = {IEEE Geoscience and Remote Sensing Letters},
Keywords = {SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, Baseline refinement, calibration, interferometry,InSAR, Motion Compensation, repeat-pass interferometry, Residual Motion Errors, RME, Squinted SAR, Multi-Squint Processing, ESAR, geophysical signal processing, geophysical techniques, motion compensation, remote sensing by radar, synthetic aperture radar SAR focusing, airborne SAR data, airborne SAR interferometry, digital elevation model, motion compensation, multisquint processing approach, navigation system, repeat-pass systems, residual motion errors, synthetic aperture radar, time-varying baseline errors},
Owner = {ofrey},
Pdf = {../../../docs/reigberPratsMallorqui2006.pdf}
}


27. E. Sansosti, P. Berardino, M. Manunta, F. Serafino, and G. Fornaro. Geometrical SAR image registration. IEEE Transactions on Geoscience and Remote Sensing, 44(10):2861-2870, October 2006. Keyword(s): SAR Processing, image registration, coregistration, InSAR, Interferometry, ENVISAT, European Remote Sensing, acquisition flight tracks, baseline spans, digital elevation model, image registration, multichannel SAR processing, satellite systems, sensitivity analysis, steep topography regions, subpixel registration, synthetic aperture radar images, two-pass interferometry, warping functions, artificial satellites, geophysical signal processing, image registration, remote sensing by radar, sensitivity analysis, synthetic aperture radar, topography (Earth).
 Abstract: Accurate subpixel registration of synthetic aperture radar (SAR) images is an issue that is again growing interest since its initial developments related to two-pass interferometry. Recent progress in coherent (multichannel) SAR processing raises the need for accurate registration of data takes acquired with large baseline spans, high temporal coverage, and with different frequency and/or operational modes. In this paper, we discuss a SAR image-registration procedure, based on the use of external measures which allows obtaining a very accurate alignment of SAR images. The presented technique makes use of a digital elevation model and of the precise information about the acquisition flight tracks, to compute the warping functions that map the position of each pixel in the different takes, thus avoiding any approximation. The resulting algorithm is simple, robust, precise, and very efficient; as a matter of fact, it may achieve high accuracy even in critical areas, such as steep topography regions. Moreover, the availability of an analytical and exact model allows performing a detailed sensitivity analysis that can be useful in evaluating the applicability of this technique even to future high-precision satellite systems. Extensive testing, carried out on several real European Remote Sensing and ENVISAT datasets, clearly shows the effectiveness of such algorithm in registering critical SAR images

@Article{1704979,
Title = {Geometrical SAR image registration},
Author = {Sansosti, E. and Berardino, P. and Manunta, M. and Serafino, F. and Fornaro, G.},
Doi = {10.1109/TGRS.2006.875787},
ISSN = {0196-2892},
Month = oct,
Number = {10},
Pages = {2861-2870},
Volume = {44},
Year = {2006},
Abstract = {Accurate subpixel registration of synthetic aperture radar (SAR) images is an issue that is again growing interest since its initial developments related to two-pass interferometry. Recent progress in coherent (multichannel) SAR processing raises the need for accurate registration of data takes acquired with large baseline spans, high temporal coverage, and with different frequency and/or operational modes. In this paper, we discuss a SAR image-registration procedure, based on the use of external measures which allows obtaining a very accurate alignment of SAR images. The presented technique makes use of a digital elevation model and of the precise information about the acquisition flight tracks, to compute the warping functions that map the position of each pixel in the different takes, thus avoiding any approximation. The resulting algorithm is simple, robust, precise, and very efficient; as a matter of fact, it may achieve high accuracy even in critical areas, such as steep topography regions. Moreover, the availability of an analytical and exact model allows performing a detailed sensitivity analysis that can be useful in evaluating the applicability of this technique even to future high-precision satellite systems. Extensive testing, carried out on several real European Remote Sensing and ENVISAT datasets, clearly shows the effectiveness of such algorithm in registering critical SAR images},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {SAR Processing, image registration, coregistration, InSAR, Interferometry, ENVISAT;European Remote Sensing;acquisition flight tracks;baseline spans;digital elevation model;image registration;multichannel SAR

processing;satellite systems;sensitivity analysis;steep topography regions;subpixel registration;synthetic aperture radar images;two-pass interferometry;warping functions;artificial satellites;geophysical signal processing;image registration;remote sensing by radar;sensitivity analysis;synthetic aperture radar;topography (Earth)}
}


28. Martin Stangl, Rolf Werninghaus, B. Schweizer, C. Fischer, Michael Brandfass, Josef Mittermayer, and Helko Breit. TerraSAR-X Technologies and First Results. Radar, Sonar & Navigation, 153(2):86 - 95, April 2006. Keyword(s): SAR Processing, TerraSAR-X, Spaceborne SAR, X-Band, Instrument Description, Imaging Modes, Stripmap, ScanSAR, Spotlight SAR, TerraSAR-X multimode SAR processor, TMSP, Chirp Scaling Algorithm, CSA, SPECAN Algorithm, SPECAN.
 Abstract: The TerraSAR-X Satellite which is currently being built in the framework of a public private partnership between the German Aerospace Centre DLR and Astrium GmbH Germany carries an X-Band SAR instrument which is equipped with an active phased array antenna. Its operational flexibility allows the use of the instrument for scientific and commercial applications. High amplitude and phase stability of the radar instrument is achieved by a Carbon Fibre Reinforced Plastic (CFRP) slotted waveguide radiator and high precision Transmit/Receive Module. Additionally internal calibration hardware allows for determination of the residual drifts. A precise Central Electronics controls the radar instrument, provides an arbitrary transmit chirp and receives the radar echo with selectable bandwidth and raw data compression ratio. The ground stations multimode SAR processor is supported by a novel satellite steering law to reduce the attitude dependent mean Doppler shift. This article summarises the EUSAR 2004 TerraSAR-X contributions.

@Article{stanglWerninghausSchweizerFischerBrandfassMittermayerBreit2006:TerraSARX,
Title = {{TerraSAR-X Technologies and First Results}},
Author = {Stangl, Martin and Werninghaus, Rolf and Schweizer, B. and Fischer, C. and Brandfass, Michael and Mittermayer, Josef and Breit, Helko},
Doi = {10.1049/ip-rsn:20045119},
Editor = {IEE},
Month = apr,
Number = {2},
Pages = {86 - 95},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1626076&isnumber=34128},
Volume = {153},
Year = {2006},
Abstract = {The TerraSAR-X Satellite which is currently being built in the framework of a public private partnership between the German Aerospace Centre DLR and Astrium GmbH Germany carries an X-Band SAR instrument which is equipped with an active phased array antenna. Its operational flexibility allows the use of the instrument for scientific and commercial applications. High amplitude and phase stability of the radar instrument is achieved by a Carbon Fibre Reinforced Plastic (CFRP) slotted waveguide radiator and high precision Transmit/Receive Module. Additionally internal calibration hardware allows for determination of the residual drifts. A precise Central Electronics controls the radar instrument, provides an arbitrary transmit chirp and receives the radar echo with selectable bandwidth and raw data compression ratio. The ground stations multimode SAR processor is supported by a novel satellite steering law to reduce the attitude dependent mean Doppler shift. This article summarises the EUSAR 2004 TerraSAR-X contributions.},
Keywords = {SAR Processing, TerraSAR-X, Spaceborne SAR, X-Band, Instrument Description, Imaging Modes, Stripmap, ScanSAR, Spotlight SAR, TerraSAR-X multimode SAR processor, TMSP, Chirp Scaling Algorithm,CSA, SPECAN Algorithm, SPECAN},
Pdf = {../../../docs/stanglWerninghausSchweizerFischerBrandfassMittermayerBreit2006.pdf},
Publisher = {IEE}
}


29. H. C. Stankwitz and S. P. Taylor. Advances in non-linear apodization. IEEE Aerospace and Electronic Systems Magazine, 21(1):3-8, January 2006. Keyword(s): SAR Processing, Apodization, Spatially Variant Apodization, SVA, NonLinear Apodization, European Soil Moisture and Ocean Salinity system, GeoSTAR, Y-type synthetic aperture radiometers, antenna size, bandwidth extrapolation, impulse response performance, irregularly-shaped apertures, microwave radar systems, microwave remote sensing, nonlinear apodization, parse coherent apertures, sidelobe control, sparse aperture filling property, superresolution algorithms, superresolution techniques, synthetic aperture radar systems, synthetic multiple aperture radar technology, microwave measurement, radar antennas, radar resolution, remote sensing by radar, synthetic aperture radar.
 Abstract: Selected new methods and applications of non-linear apodization for irregularly-shaped and parse coherent apertures and arrays are presented. The benefits include unproved impulse response performance, i.e., reduced peak sidelobes and integrated sidelobe power, along with improved mainlobe resolution, compared to classic windowing techniques. Nonlinear apodization (NLA) techniques can also serve as powerful engines for effective superresolution and bandwidth extrapolation of coherent data for filling sparse apertures. The sparse aperture filling property of superresolution algorithms for radar data forms the basis for a new concept which is introduced here: synthetic multiple aperture radar technology (SMART). Increased swath and/or reduced antenna size are some of the benefits postulated for SMART applied to synthetic aperture radar (SAR) systems. The benefits of these new methods and applications for nonlinear apodization are then demonstrated for two specific applications: 1) sidelobe control for Y-type synthetic aperture radiometers, such as the European Soil Moisture and Ocean Salinity (SMOS) system (Kerr et al.) and JPL's proposed GeoSTAR (Lambrigsten) concept; and, 2) filling of sparse synthetic aperture radar data by exploiting the bandwidth extrapolation properties of nonlinear apodization based superresolution techniques. The methods that have been developed and demonstrated herein have potential application to a wide range of passive and active microwave remote sensing and radar systems.

@Article{stankwitzTaylor2006:NonLinearApodization,
author = {Stankwitz, H. C. and Taylor, S. P.},
journal = {IEEE Aerospace and Electronic Systems Magazine},
title = {Advances in non-linear apodization},
year = {2006},
issn = {0885-8985},
month = jan,
number = {1},
pages = {3-8},
volume = {21},
abstract = {Selected new methods and applications of non-linear apodization for irregularly-shaped and parse coherent apertures and arrays are presented. The benefits include unproved impulse response performance, i.e., reduced peak sidelobes and integrated sidelobe power, along with improved mainlobe resolution, compared to classic windowing techniques. Nonlinear apodization (NLA) techniques can also serve as powerful engines for effective superresolution and bandwidth extrapolation of coherent data for filling sparse apertures. The sparse aperture filling property of superresolution algorithms for radar data forms the basis for a new concept which is introduced here: synthetic multiple aperture radar technology (SMART). Increased swath and/or reduced antenna size are some of the benefits postulated for SMART applied to synthetic aperture radar (SAR) systems. The benefits of these new methods and applications for nonlinear apodization are then demonstrated for two specific applications: 1) sidelobe control for Y-type synthetic aperture radiometers, such as the European Soil Moisture and Ocean Salinity (SMOS) system (Kerr et al.) and JPL's proposed GeoSTAR (Lambrigsten) concept; and, 2) filling of sparse synthetic aperture radar data by exploiting the bandwidth extrapolation properties of nonlinear apodization based superresolution techniques. The methods that have been developed and demonstrated herein have potential application to a wide range of passive and active microwave remote sensing and radar systems.},
keywords = {SAR Processing, Apodization, Spatially Variant Apodization, SVA, NonLinear Apodization, European Soil Moisture and Ocean Salinity system, GeoSTAR, Y-type synthetic aperture radiometers, antenna size, bandwidth extrapolation, impulse response performance, irregularly-shaped apertures, microwave radar systems, microwave remote sensing, nonlinear apodization, parse coherent apertures, sidelobe control, sparse aperture filling property, superresolution algorithms, superresolution techniques, synthetic aperture radar systems, synthetic multiple aperture radar technology, microwave measurement, radar antennas, radar resolution, remote sensing by radar, synthetic aperture radar},

}


30. Z. Su, Y. Peng, and X. Wang. Evaluation of the Aperture in the Curvilinear SAR. Radar, 2006. CIE'06. International Conference on, pp 1-4, 2006. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR.
 Abstract: The curvilinear synthetic aperture radar (SAR), as a more practicable three-dimensional (3-D) SAR imaging system, has to utilize the parametric methods to extract the target features from its received data, the sparse data in 3-D frequency space. With the obtained feature estimates, these parametric methods, who can efficiently remove the effects of the sidelobes, reconstruct the target image whose quality is affected by the estimation accuracy of the features. By minimizing the Cramer-Rao bounds (CRBs) of the target features, we show, in this paper, the different effects on the estimation accuracy of different aperture parameters. A feature-independent aperture evaluator is also given for the curvilinear SAR system.

@Article{suPengWang2006:NonLinearSARTomo,
Title = {{Evaluation of the Aperture in the Curvilinear SAR}},
Author = {Su, Z. and Peng, Y. and Wang, X.},
Pages = {1--4},
Url = {http://ieeexplore.ieee.org/iel5/4148130/4118064/04148144.pdf},
Year = {2006},
Abstract = {The curvilinear synthetic aperture radar (SAR), as a more practicable three-dimensional (3-D) SAR imaging system, has to utilize the parametric methods to extract the target features from its received data, the sparse data in 3-D frequency space. With the obtained feature estimates, these parametric methods, who can efficiently remove the effects of the sidelobes, reconstruct the target image whose quality is affected by the estimation accuracy of the features. By minimizing the Cramer-Rao bounds (CRBs) of the target features, we show, in this paper, the different effects on the estimation accuracy of different aperture parameters. A feature-independent aperture evaluator is also given for the curvilinear SAR system.},
Journal = {Radar, 2006. CIE'06. International Conference on},
Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR},
Pdf = {../../../docs/suPengWang2006.pdf}
}


 Abstract: The interpretation of radar data would ideally require extensive and numerous observations. However, the number of observations is limited by the difficulty and the cost of acquiring ground truth and radar data. On the other hand, numerical models can provide a wide range of situations, both in inputs and in outputs. More precisely, they have to provide radiometric, polarimetric, and interferometric simulations and be applicable to various forested areas (high density, high/low moisture, inhomogeneous area, etc.) and radar configurations (low/high frequency, bistatic observation, etc.). This paper is dedicated to the presentation of the capabilities of a descriptive coherent scattering model (COSMO) applied to the electromagnetic study of the backscattering by forested areas. Improvements have been implemented in order to produce in output a radar image, which can be treated with the same polarimetric and interferometric tools as those applied to real synthetic aperture radar images. Thus, comparisons are possible. COSMO has been widely tested from P- to L- bands, over temperate and tropical forests and applied to radiometry, polarimetry, and interferometry. It appears finally as an efficient simulating tool to carry out parametric studies and to analyze how the total scattered field is built from canonical mechanisms and individual scatterer contributions.

@Article{thirionColinDahon2006,
author = {Thirion, L. and Colin, E. and Dahon, C.},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
title = {Capabilities of a forest coherent scattering model applied to radiometry, interferometry, and polarimetry at P- and L-band},
year = {2006},
issn = {0196-2892},
month = apr,
number = {4},
pages = {849 - 862},
volume = {44},
abstract = {The interpretation of radar data would ideally require extensive and numerous observations. However, the number of observations is limited by the difficulty and the cost of acquiring ground truth and radar data. On the other hand, numerical models can provide a wide range of situations, both in inputs and in outputs. More precisely, they have to provide radiometric, polarimetric, and interferometric simulations and be applicable to various forested areas (high density, high/low moisture, inhomogeneous area, etc.) and radar configurations (low/high frequency, bistatic observation, etc.). This paper is dedicated to the presentation of the capabilities of a descriptive coherent scattering model (COSMO) applied to the electromagnetic study of the backscattering by forested areas. Improvements have been implemented in order to produce in output a radar image, which can be treated with the same polarimetric and interferometric tools as those applied to real synthetic aperture radar images. Thus, comparisons are possible. COSMO has been widely tested from P- to L- bands, over temperate and tropical forests and applied to radiometry, polarimetry, and interferometry. It appears finally as an efficient simulating tool to carry out parametric studies and to analyze how the total scattered field is built from canonical mechanisms and individual scatterer contributions.},
doi = {10.1109/TGRS.2005.862523},

}


32. W. L. Van Rossum, M. P. G. Otten, and R. J. P. Van Bree. Extended PGA for range migration algorithms. IEEE Transactions on Aerospace and Electronic Systems, 42(2):478-488, April 2006. Keyword(s): SAR Proceedings, Autofocus, Phase Gradient Autofocus, PGA, gradient methods, radar imaging, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Spotlight SAR, synthetic aperture radar.
 Abstract: The phase gradient autofocus (PGA) algorithm is extended to work for synthetic aperture radar (SAR) spotlight images processed with range migration (w-k) algorithms. Several pre-processing steps are proposed for aligning the range-compressed phase-history data needed for successful autofocusing of the data. The proposed algorithm gave good results for both data with large point targets and data without point targets.

@Article{vanRossumOttenVanBree2006:PGAAutofocus,
Title = {{Extended PGA for range migration algorithms}},
Author = {Van Rossum, W. L. and Otten, M. P. G. and Van Bree, R. J. P.},
Doi = {10.1109/TAES.2006.1642565},
ISSN = {0018-9251},
Month = {apr},
Number = {2},
Pages = {478-488},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4422846&isnumber=4422708},
Volume = {42},
Year = {2006},
Abstract = {The phase gradient autofocus (PGA) algorithm is extended to work for synthetic aperture radar (SAR) spotlight images processed with range migration (w-k) algorithms. Several pre-processing steps are proposed for aligning the range-compressed phase-history data needed for successful autofocusing of the data. The proposed algorithm gave good results for both data with large point targets and data without point targets.},
Journal = {IEEE Transactions on Aerospace and Electronic Systems},
Keywords = {SAR Proceedings, Autofocus, Phase Gradient Autofocus, PGA, gradient methods, radar imaging, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Spotlight SAR, synthetic aperture radar},
Pdf = {../../../docs/vanRossumOttenVanBree2006.pdf}
}


33. I. Walterscheid, J.H.G. Ender, A.R. Brenner, and O. Loffeld. Bistatic SAR Processing and Experiments. IEEE Trans. Geosci. Remote Sens., 44(10):2710-2717, October 2006. Keyword(s): SAR Processing, Bistatic SAR, Airborne Experimental Radar II, Forschungsgesellschaft fur Angewandte Naturwissenschaften, Phased Array Multifunctional Imaging Radar, X-band SAR systems, antenna pointing, bistatic SAR, bistatic reflectivity, flight coordination, forward-looking SAR imaging, motion compensation, radar cross section, range migration algorithm, receive gate timing, synthetic aperture radar, transmit pulse, airborne radar, geophysical signal processing, geophysical techniques, radar imaging, remote sensing by radar, synthetic aperture radar.
 Abstract: Bistatic synthetic aperture radar (SAR) uses a separated transmitter and receiver flying on different platforms to achieve benefits like exploitation of additional information contained in the bistatic reflectivity of targets, reduced vulnerability for military applications, forward-looking SAR imaging, or increased radar cross section. Besides technical problems such as synchronization of the oscillators, involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, and motion compensation, the development of a bistatic focusing algorithm is still in progress and not sufficiently solved. As a step to a numerically efficient processor, this paper presents a bistatic range migration algorithm for the translationally invariant case, where transmitter and receiver have equal velocity vectors. In this paper, the algorithm was successfully applied to simulated and real bistatic data. The real bistatic data have been acquired with the Forschungsgesellschaft fur Angewandte Naturwissenschaften (FGAN)'s X-band SAR systems, namely the Airborne Experimental Radar II and the Phased Array Multifunctional Imaging Radar, in October 2003

@Article{WalterscheidEnderBrennerLoffeld2006:Bistatic,
Title = {Bistatic {SAR} Processing and Experiments},
Author = {Walterscheid, I. and Ender, J.H.G. and Brenner, A.R. and Loffeld, O.},
Doi = {10.1109/TGRS.2006.881848},
ISSN = {0196-2892},
Month = oct,
Number = {10},
Pages = {2710-2717},
Volume = {44},
Year = {2006},
Abstract = {Bistatic synthetic aperture radar (SAR) uses a separated transmitter and receiver flying on different platforms to achieve benefits like exploitation of additional information contained in the bistatic reflectivity of targets, reduced vulnerability for military applications, forward-looking SAR imaging, or increased radar cross section. Besides technical problems such as synchronization of the oscillators, involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, and motion compensation, the development of a bistatic focusing algorithm is still in progress and not sufficiently solved. As a step to a numerically efficient processor, this paper presents a bistatic range migration algorithm for the translationally invariant case, where transmitter and receiver have equal velocity vectors. In this paper, the algorithm was successfully applied to simulated and real bistatic data. The real bistatic data have been acquired with the Forschungsgesellschaft fur Angewandte Naturwissenschaften (FGAN)'s X-band SAR systems, namely the Airborne Experimental Radar II and the Phased Array Multifunctional Imaging Radar, in October 2003},
Journal = {IEEE Trans. Geosci. Remote Sens.},
}


34. L. Xiangle and Y. Ruliang. Study of Composite Mode Curvilinear SAR. Radar, 2006. CIE'06. International Conference on, pp 1-4, 2006. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR.
 Abstract: A new mode of curvilinear SAR called composite mode curvilinear SAR(CCLSAR) is proposed in this paper. In CCLSAR, the SAR operates in strip mode in azimuth and range dimension but spotlight mode in the height dimension. CCLSAR can synthesize a very large aperture in the direction of height, which cause very high resolution in the height dimension. Compared with the conventional curvilinear SAR, CCLSAR can acquire the imaging of large terrain quickly and immediately. Firstly the CCLSAR scheme was proposed and then the primary three-dimensional imaging in the case of full aperture of CCLSAR was discussed in this paper.

@Article{xiangleRulinag2006:NonLinearSARTomo,
Title = {{Study of Composite Mode Curvilinear SAR}},
Author = {Xiangle, L. and Ruliang, Y.},
Pages = {1--4},
Url = {http://ieeexplore.ieee.org/iel5/4148130/4118064/04148428.pdf},
Year = {2006},
Abstract = {A new mode of curvilinear SAR called composite mode curvilinear SAR(CCLSAR) is proposed in this paper. In CCLSAR, the SAR operates in strip mode in azimuth and range dimension but spotlight mode in the height dimension. CCLSAR can synthesize a very large aperture in the direction of height, which cause very high resolution in the height dimension. Compared with the conventional curvilinear SAR, CCLSAR can acquire the imaging of large terrain quickly and immediately. Firstly the CCLSAR scheme was proposed and then the primary three-dimensional imaging in the case of full aperture of CCLSAR was discussed in this paper.},
Journal = {Radar, 2006. CIE'06. International Conference on},
Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR},
Pdf = {../../../docs/xiangleRuliang2006.pdf}
}


35. Y. Yamaguchi, Y. Yajima, and H. Yamada. A four-component decomposition of POLSAR images based on the coherency matrix. IEEE Geosci. Remote Sens. Lett., 3(3):292 -296, July 2006. Keyword(s): POLSAR image decomposition, coherency matrix, covariance matrix, four-component decomposition, nonreflection symmetric scattering, polarimetric SAR, synthetic aperture radar, covariance matrices, geophysical techniques, image processing, radar polarimetry, remote sensing by radar, synthetic aperture radar;.
 Abstract: A four-component decomposition scheme of the coherency matrix is presented here for the analysis of polarimetric synthetic aperture radar (SAR) images. The coherency matrix is used to deal with nonreflection symmetric scattering case, which is an extension of covariance matrix approach. The same decomposition results have been obtained. The advantage of this approach is explicit expressions of four scattering powers in terms of scattering matrix elements, which serve the interpretation of polarimetric SAR data quantitatively

@Article{yamaguchiYajimaYamada2006,
author = {Yamaguchi, Y. and Yajima, Y. and Yamada, H.},
title = {A four-component decomposition of {POLSAR} images based on the coherency matrix},
journal = {IEEE Geosci. Remote Sens. Lett.},
year = {2006},
volume = {3},
number = {3},
pages = {292 -296},
month = jul,
issn = {1545-598X},
abstract = {A four-component decomposition scheme of the coherency matrix is presented here for the analysis of polarimetric synthetic aperture radar (SAR) images. The coherency matrix is used to deal with nonreflection symmetric scattering case, which is an extension of covariance matrix approach. The same decomposition results have been obtained. The advantage of this approach is explicit expressions of four scattering powers in terms of scattering matrix elements, which serve the interpretation of polarimetric SAR data quantitatively},
doi = {10.1109/LGRS.2006.869986},

}


 Abstract: In this paper the concept of point-like coherent scatterers (CSs) in urban areas is introduced. The detection of CSs in single and quad-polarized images is addressed and applied on polarimetric and interferometric high-resolution airborne SAR data at L-band. For the detection of CSs two different approaches are proposed and their individual performance is analyzed. The properties of the detected CSs and their polarimetric and interferometric characteristics are assessed. The role of polarimetry on the detection of the CSs is evaluated and the potential of extracting the orientation and dielectric properties of individual CSs is finally addressed.

@Article{zandonaSchneiderPapathanassiouHajnsekMoreira2006,
author = {Zandon{\'a}-Schneider, Rafael and Papathanassiou, K.P. and Hajnsek, Irena and Moreira, Alberto},
title = {Polarimetric and interferometric characterization of coherent scatterers in urban areas},
journal = {IEEE Trans. Geosci. Remote Sens.},
year = {2006},
volume = {44},
number = {4},
pages = {971-984},
issn = {0196-2892},
abstract = {In this paper the concept of point-like coherent scatterers (CSs) in urban areas is introduced. The detection of CSs in single and quad-polarized images is addressed and applied on polarimetric and interferometric high-resolution airborne SAR data at L-band. For the detection of CSs two different approaches are proposed and their individual performance is analyzed. The properties of the detected CSs and their polarimetric and interferometric characteristics are assessed. The role of polarimetry on the detection of the CSs is evaluated and the potential of extracting the orientation and dielectric properties of individual CSs is finally addressed.},
doi = {10.1109/TGRS.2005.860950},
file = {:zandonaSchneiderPapathanassiouHajnsekMoreira2006.pdf:PDF},
pdf = {../../../docs/zandonaSchneiderPapathanassiouHajnsekMoreira2006.pdf},

}


 Abstract: The combination of compact frequency-modulated continuous-wave (FM-CW) technology and high-resolution synthetic aperture radar (SAR) processing techniques should pave the way for the development of a lightweight, cost-effective, high-resolution, airborne imaging radar. Regarding FM-CW SAR signal processing, the motion during the transmission of a sweep and the reception of the corresponding echo were expected to be one of the major problems. In FM-CW SAR, the so-called stop-and-go approximation is no longer valid due to the relatively long sweeps that FM-CW radars transmit. The main effect of the continuous motion is a Doppler frequency shift throughout the SAR observation time. This Doppler frequency shift can be compensated for by modifying the range migration compensation.

@Article{deWitMetaHoogeboomTGRS2006ModRangeDopplerForFMCWSAR,
author = {de Wit, J. J. M. and Meta, Adriano and Hoogeboom, Peter},
title = {Modified range-{Doppler} processing for {FM-CW} synthetic aperture radar},
journal = {IEEE Geoscience and Remote Sensing Letters},
year = {2006},
volume = {3},
number = {1},
pages = {83-87},
month = jan,
issn = {1545-598X},
abstract = {The combination of compact frequency-modulated continuous-wave (FM-CW) technology and high-resolution synthetic aperture radar (SAR) processing techniques should pave the way for the development of a lightweight, cost-effective, high-resolution, airborne imaging radar. Regarding FM-CW SAR signal processing, the motion during the transmission of a sweep and the reception of the corresponding echo were expected to be one of the major problems. In FM-CW SAR, the so-called stop-and-go approximation is no longer valid due to the relatively long sweeps that FM-CW radars transmit. The main effect of the continuous motion is a Doppler frequency shift throughout the SAR observation time. This Doppler frequency shift can be compensated for by modifying the range migration compensation.},
doi = {10.1109/LGRS.2005.856700},
file = {:deWitMetaHoogeboomTGRS2006ModRangeDopplerForFMCWSAR.pdf:PDF},
owner = {ofrey},
pdf = {../../../docs/deWitMetaHoogeboomTGRS2006ModRangeDopplerForFMCWSAR.pdf},

}


### Conference articles

1. E. Candes and J. Romberg. Robust Signal Recovery from Incomplete Observations. In Proc. IEEE Int. Conf. Image Processing, pages 1281-1284, October 2006. Keyword(s): convex optimization program, linear measurement, sparse signal reconstruction, convex programming, signal reconstruction;.
 Abstract: Recently, a series of exciting results have shown that it is possible to reconstruct a sparse signal exactly from a very limited number of linear measurements by solving a convex optimization program. If our underlying signal f can be written as a superposition of B elements from a known basis, it is possible to recover f from a projection onto a generic subspace of dimension about B log N. Moreover, the procedure is robust to measurement error; adding a perturbation of size isin to the measurements will not induce a recovery error of more than a small constant times isin. In this paper, we will briefly overview these results, and show how the recovery via convex optimization can be implemented in an efficient manner, and present some numerical results illustrating the practicality of the procedure.

@InProceedings{4106771,
Title = {Robust Signal Recovery from Incomplete Observations},
Author = {Candes, E. and Romberg, J.},
Booktitle = {Proc. IEEE Int. Conf. Image Processing},
Doi = {10.1109/ICIP.2006.312579},
Month = oct,
Pages = {1281-1284},
Year = {2006},
Abstract = {Recently, a series of exciting results have shown that it is possible to reconstruct a sparse signal exactly from a very limited number of linear measurements by solving a convex optimization program. If our underlying signal f can be written as a superposition of B elements from a known basis, it is possible to recover f from a projection onto a generic subspace of dimension about B log N. Moreover, the procedure is robust to measurement error; adding a perturbation of size isin to the measurements will not induce a recovery error of more than a small constant times isin. In this paper, we will briefly overview these results, and show how the recovery via convex optimization can be implemented in an efficient manner, and present some numerical results illustrating the practicality of the procedure.},
ISSN = {1522-4880},
Keywords = {convex optimization program;linear measurement;sparse signal reconstruction;convex programming;signal reconstruction;}
}


2. H. Chen and D. Kasilingam. Auto-Regressive Aperture Extrapolation for Multibaseline SAR Tomography. In Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on, pages 3743-3745, July 2006.
@InProceedings{Chen2006,
Title = {Auto-Regressive Aperture Extrapolation for Multibaseline SAR Tomography},
Author = {Chen, H. and Kasilingam, D.},
Booktitle = {Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on},
Month = jul,
Pages = {3743--3745},
Year = {2006},
Owner = {ofrey},
Timestamp = {2009.07.01}
}


3. Karlus A. Câmara de Macedo, Rolf Scheiber, and Alberto Moreira. First Evaluations of Airborne InSAR Time-Series. In Proc. of EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar, 2006. Keyword(s): SAR Processing, PSI, Persistent Scatterer Interferometry, Differential SAR Interferometry, Permanent Scatterers, Phase Gradient Autofocus, PS-PGA, Autofocus, Motion Compensation, Residual Motion Error, Repeat-Pass Interferometry, Phase Calibration, Baseline Calibration, Tomographic Baseline Calibration, Airborne SAR, E-SAR.
 Abstract: To allow time-series analysis of airborne SAR images using PSs (Permanent Scatterers), this paper has two main objectives. The first is to show, in a quantitative way, that there is a compromise between the number of images used to detect PSs, their probability of being detected and their stability. This tradeoff is derived based on estimation and detection theories. The second objective is to investigate the possibility of the use of permanent scatterers to estimate undesired phase undulations in airborne data due to residual motion errors. A new technique is proposed, the so-called PS-PGA, where we apply the Phase Gradient algorithm on the PSs in order to obtain sub-wavelength estimations of residual motion errors for both master and slaves, separately, differently from current approaches. Compensation of these residual errors will lead to more reliable airborne D-InSAR measurements.

@InProceedings{deMacedoScheiberMoreira2006:InSAR,
Title = {{First Evaluations of Airborne InSAR Time-Series}},
Author = {C{\^a}mara de Macedo, Karlus A. and Rolf Scheiber and Alberto Moreira},
Booktitle = {Proc. of EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar},
Year = {2006},
Abstract = {To allow time-series analysis of airborne SAR images using PSs (Permanent Scatterers), this paper has two main objectives. The first is to show, in a quantitative way, that there is a compromise between the number of images used to detect PSs, their probability of being detected and their stability. This tradeoff is derived based on estimation and detection theories. The second objective is to investigate the possibility of the use of permanent scatterers to estimate undesired phase undulations in airborne data due to residual motion errors. A new technique is proposed, the so-called PS-PGA, where we apply the Phase Gradient algorithm on the PSs in order to obtain sub-wavelength estimations of residual motion errors for both master and slaves, separately, differently from current approaches. Compensation of these residual errors will lead to more reliable airborne D-InSAR measurements.},
Keywords = {SAR Processing, PSI, Persistent Scatterer Interferometry, Differential SAR Interferometry, Permanent Scatterers, Phase Gradient Autofocus, PS-PGA, Autofocus, Motion Compensation, Residual Motion Error, Repeat-Pass Interferometry, Phase Calibration, Baseline Calibration, Tomographic Baseline Calibration, Airborne SAR, E-SAR},
Owner = {ofrey},
Pdf = {../../../docs/deMacedoScheiberMoreira2006.pdf}
}


4. An Daoxiang, Huang Xiaotao, and Wang Liang. Contrast Optimized PGA Algorithm for P-band UWB SAR. In Radar, 2006. CIE '06. International Conference on, pages 1-4, Oct. 2006. Keyword(s): SAR Processing, Autofocus, Phase Gradient Autofocus, Contrast Optimization.
 Abstract: The Phase Gradient Autofocus (PGA) technique has been proved to be a superior method for higher order autofocus. However, given the different nature of P-band Ultra-Wideband Synthetic Aperture Radar (UWB SAR) imagery and very low signal-to-clutter ratio in the data, conventional PGA algorithm usually fail to yield robust focusing result on raw data without distortion. We proposed the modified PGA algorithm that combines the traditional PGA with contrast optimization principle and reference scatterer coregistration. Our method is successfully applied on raw P-band UWB SAR image and excellent results are attained.

@InProceedings{Daoxiang2006,
author = {Daoxiang, An and Xiaotao, Huang and Liang, Wang},
booktitle = {Radar, 2006. CIE '06. International Conference on},
title = {Contrast Optimized PGA Algorithm for P-band UWB SAR},
year = {2006},
month = {Oct.},
pages = {1--4},
abstract = {The Phase Gradient Autofocus (PGA) technique has been proved to be a superior method for higher order autofocus. However, given the different nature of P-band Ultra-Wideband Synthetic Aperture Radar (UWB SAR) imagery and very low signal-to-clutter ratio in the data, conventional PGA algorithm usually fail to yield robust focusing result on raw data without distortion. We proposed the modified PGA algorithm that combines the traditional PGA with contrast optimization principle and reference scatterer coregistration. Our method is successfully applied on raw P-band UWB SAR image and excellent results are attained.},
keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus, Contrast Optimization},
owner = {ofrey},
pdf = {../../../docs/daoxiangXiaotaoLiang2006.pdf},

}


5. Cao Fang, Hong Wen, and Wu Yirong. An improved Cloude-Pottier decomposition using H/alpha/SPAN and complex Wishart classifier for polarimetric SAR classification. In International Conference on Radar, 2006. CIE '06., pages 1-4, October 2006. Keyword(s): image classification, radar imaging, radar polarimetry, synthetic aperture radarCloude-Pottier decomposition, H/alpha/SPAN, IHSL transform, Wishart classifier, polarimetric SAR classification, synthetic aperture radar.
 Abstract: An improvement is proposed for the Cloude-Pottier decomposition using H/alpha/SPAN and IHSL transform. Based on this decomposition, an unsupervised classification with SPAN is also given in this paper. The main advantages of this decomposition are that it uses SPAN to maintain the space information for further polarimetric analysis and provides a straight way to present the result. Our experiments show that this decomposition method provides better results than the general Cloude-Pottier method and the corresponding Wishart H/alpha/SPAN classification also achieves better performance than the current Wishart H/alpha/A method

@InProceedings{fangWenYirong2006:EntropyAlphaSpan,
Title = {{An improved Cloude-Pottier decomposition using H/alpha/SPAN and complex Wishart classifier for polarimetric SAR classification}},
Author = {Cao Fang and Hong Wen and Wu Yirong},
Booktitle = {International Conference on Radar, 2006. CIE '06.},
Doi = {10.1109/ICR.2006.343203},
Month = oct,
Pages = {1-4},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4148309&isnumber=4118064},
Year = {2006},
Abstract = {An improvement is proposed for the Cloude-Pottier decomposition using H/alpha/SPAN and IHSL transform. Based on this decomposition, an unsupervised classification with SPAN is also given in this paper. The main advantages of this decomposition are that it uses SPAN to maintain the space information for further polarimetric analysis and provides a straight way to present the result. Our experiments show that this decomposition method provides better results than the general Cloude-Pottier method and the corresponding Wishart H/alpha/SPAN classification also achieves better performance than the current Wishart H/alpha/A method},
Keywords = {image classification, radar imaging, radar polarimetry, synthetic aperture radarCloude-Pottier decomposition, H/alpha/SPAN, IHSL transform, Wishart classifier, polarimetric SAR classification, synthetic aperture radar},
Owner = {ofrey},
Pdf = {../../../docs/fangWenYirong2006.pdf}
}


6. Othmar Frey, Erich Meier, and Daniel Nüesch. An Integrated Focusing and Calibration Procedure for Airborne SAR Data. In Proc. EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar, 2006. Keyword(s): SAR Processing, Time-Domain Back-Projection, Back-Projection, Terrain Correction, Radiometry, Radiometric Calibration, Radiometric Correction, Terrain, Topography, DEM Geocoding, Geocoding, DLR, E-SAR, Airborne SAR, L-Band.
 Abstract: Topography-induced variation of radar brightness still poses a problem in terms of radiometric calibration of SAR data, which is undoubtedly an indispensable step in order to deduce bio- or geophysical parameters from amplitude images. We propose an integrated focusing and calibration procedure for airborne SAR data based on the time-domain backprojection technique. With the help of sensor position and attitude data as well as a digital elevation model (DEM) the true acquisition geometry is maintained throughout the combined focusing and calibration step. The effectiveness of the method is evaluated by means of an E-SAR L-band data set acquired over undulating terrain.

@InProceedings{freyMeierNueschEusar2006:TDBP,
author = {Othmar Frey and Erich Meier and Daniel N{\"u}esch},
title = {An Integrated Focusing and Calibration Procedure for Airborne SAR Data},
booktitle = {Proc. EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar},
year = {2006},
abstract = {Topography-induced variation of radar brightness still poses a problem in terms of radiometric calibration of SAR data, which is undoubtedly an indispensable step in order to deduce bio- or geophysical parameters from amplitude images. We propose an integrated focusing and calibration procedure for airborne SAR data based on the time-domain backprojection technique. With the help of sensor position and attitude data as well as a digital elevation model (DEM) the true acquisition geometry is maintained throughout the combined focusing and calibration step. The effectiveness of the method is evaluated by means of an E-SAR L-band data set acquired over undulating terrain.},
file = {:freyMeierNueschEusar2006.pdf:PDF},
keywords = {SAR Processing, Time-Domain Back-Projection, Back-Projection, Terrain Correction, Radiometry, Radiometric Calibration, Radiometric Correction, Terrain, Topography, DEM Geocoding, Geocoding, DLR, E-SAR, Airborne SAR, L-Band},
owner = {ofrey},
pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMeierNueschEusar2006.pdf},

}


7. Per-Olov Frölind and Lars M. H. Ulander. Evaluation of angular interpolation kernels in fast back-projection SAR processing. In IEE Proceedings -- Radar, Sonar and Navigation, volume 153, pages 243-249, June 2006. Keyword(s): SAR Processing, Time-Domain Back-Projection, Back-Projection, Back-Projection, Fast Factorized Back-Projection, Comparison of Algorithms, interpolation, interpolation kernels, angular interpolation kernels, radar imaging, synthetic aperture radar, ultra wideband radar, UWB SAR, interpolation method, phase error, polar version, subimage version, time domain SAR algorithm, Factorized Backprojection.
 Abstract: This paper presents a comparative study of the polar and the subimage based variants of the time domain SAR algorithm Fast Factorized Backprojection. The difference between the two variants with regard to the phase error, which causes defocusing in the image, is investigated. The difference between the algorithms in interpolation between stages is also discussed. To investigate the sidelobes in azimuth, the paper gives simulation results for a low frequency UWB SAR system for both algorithms. How the algorithms differ with regard to amount of beams and length of beams is also discussed.

@InProceedings{froelindUlander2006:FFBP,
Title = {Evaluation of angular interpolation kernels in fast back-projection SAR processing},
Author = {Per-Olov Fr{\"o}lind and Lars M. H. Ulander},
Month = {jun},
Number = {3},
Pages = {243--249},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1648543&isnumber=34563},
Volume = {153},
Year = {2006},
Abstract = {This paper presents a comparative study of the polar and the subimage based variants of the time domain SAR algorithm Fast Factorized Backprojection. The difference between the two variants with regard to the phase error, which causes defocusing in the image, is investigated. The difference between the algorithms in interpolation between stages is also discussed. To investigate the sidelobes in azimuth, the paper gives simulation results for a low frequency UWB SAR system for both algorithms. How the algorithms differ with regard to amount of beams and length of beams is also discussed.},
ISSN = {1350-2395},
Keywords = {SAR Processing, Time-Domain Back-Projection, Back-Projection, Back-Projection, Fast Factorized Back-Projection, Comparison of Algorithms, interpolation,interpolation kernels, angular interpolation kernels, radar imaging, synthetic aperture radar, ultra wideband radar, UWB SAR, interpolation method, phase error, polar version, subimage version, time domain SAR algorithm,Factorized Backprojection},
Owner = {ofrey},
Pdf = {../../../docs/froelindUlander2006.pdf}
}


8. Charles V. Jakowatz and Neall Doren. Comparison of polar formatting and back-projection algorithms for spotlight-mode SAR image formation. In Edmund G. Zelnio and Frederick D. Garber, editors, , volume 6237, pages 62370H, 2006. SPIE. Keyword(s): SAR Processing, Polar Format Algorithm, PFA, Convolution Backprojection Algorithm, CPB, Comparison of Algorithms, Spotlight SAR, Spotlight-mode data.
@Conference{jakowatzDorenPFABackprojectionComparison2006,
author = {Charles V. Jakowatz and Neall Doren},
title = {Comparison of polar formatting and back-projection algorithms for spotlight-mode {SAR} image formation},
year = {2006},
editor = {Edmund G. Zelnio and Frederick D. Garber},
volume = {6237},
number = {1},
pages = {62370H},
publisher = {SPIE},
doi = {10.1117/12.673249},
eid = {62370H},
file = {:jakowatzDorenPFABackprojectionComparison2006.pdf:PDF},
journal = {Algorithms for Synthetic Aperture Radar Imagery XIII},
keywords = {SAR Processing, Polar Format Algorithm, PFA, Convolution Backprojection Algorithm, CPB, Comparison of Algorithms, Spotlight SAR, Spotlight-mode data},
location = {Orlando (Kissimmee), FL, USA},
numpages = {7},
owner = {ofrey},
pdf = {../../../docs/jakowatzDorenPFABackprojectionComparison2006.pdf},

}


9. Charles V. Jakowatz and Daniel E. Wahl. Correction of propagation-induced defocus effects in certain spotlight-mode SAR collections. In Edmund G. Zelnio and Frederick D. Garber, editors, , volume 6237, pages 62370I, 2006. SPIE. Keyword(s): SAR Processing, Polar Format Algorithm, PFA, Atmospheric Influence, Phase Gradient Algorithm, PGA, Autofocus, Residual Phase Errors, Residual Error, Spotlight SAR, Spotlight-mode data.
@Conference{jakowatzWahlPGASpotlightmode2006,
author = {Charles V. Jakowatz and Daniel E. Wahl},
title = {Correction of propagation-induced defocus effects in certain spotlight-mode {SAR} collections},
year = {2006},
editor = {Edmund G. Zelnio and Frederick D. Garber},
volume = {6237},
number = {1},
pages = {62370I},
publisher = {SPIE},
doi = {10.1117/12.673302},
eid = {62370I},
file = {:jakowatzWahlPGASpotlightmode2006.pdf:PDF},
journal = {Algorithms for Synthetic Aperture Radar Imagery XIII},
keywords = {SAR Processing, Polar Format Algorithm, PFA, Atmospheric Influence, Phase Gradient Algorithm, PGA, Autofocus, Residual Phase Errors, Residual Error, Spotlight SAR, Spotlight-mode data},
location = {Orlando (Kissimmee), FL, USA},
numpages = {6},
owner = {ofrey},
pdf = {../../../docs/jakowatzWahlPGASpotlightmode2006.pdf},

}


10. Bert M. Kampes and Nico Adam. The STUN algorithm for persistent scatterer interferometry. In Fringe 2005 Workshop, volume 610, 2006.
@InProceedings{kampesAdamFRINGE2006STUNalgoPSI,
author = {Kampes, Bert M. and Adam, Nico},
title = {The {STUN} algorithm for persistent scatterer interferometry},
booktitle = {Fringe 2005 Workshop},
year = {2006},
volume = {610},
owner = {ofrey},

}


11. Fabrizio Lombardini, Ludwig Rössing, Joachim H. G. Ender, and F. Cai. Interferometric Model Order Selection: Validation of ITC Methods with Airborne Three-antenna SAR Data. In Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on, pages 2565-2568, July 2006.
@InProceedings{Lombardini2006,
Title = {Interferometric Model Order Selection: Validation of ITC Methods with Airborne Three-antenna SAR Data},
Author = {Lombardini, Fabrizio and R{\"o}ssing, Ludwig and Joachim H. G. Ender and Cai, F.},
Booktitle = {Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on},
Month = jul,
Pages = {2565--2568},
Year = {2006},
Owner = {ofrey}
}


12. J.M. Munoz-Ferreras, J. Calvo-Gallego, F. Perez-Martinez, A. Blanco-del-Campo, A. Asensio-Lopez, and B.P. Dorta-Naranjo. Motion compensation for ISAR based on the shift-and-convolution algorithm. In IEEE Conference on Radar, pages 1-5, April 2006. Keyword(s): ISAR.
@InProceedings{Munoz-Ferreras2006,
Title = {Motion compensation for {ISAR} based on the shift-and-convolution algorithm},
Author = {Munoz-Ferreras, J.M. and Calvo-Gallego, J. and Perez-Martinez, F. and Blanco-del-Campo, A. and Asensio-Lopez, A. and Dorta-Naranjo, B.P.},
Booktitle = {IEEE Conference on Radar},
Month = apr,
Pages = {1-5},
Year = {2006},
Keywords = {ISAR},
Owner = {ofrey}
}


13. Matteo Nannini and Rolf Scheiber. A Time Domain Beamforming Algorithm for SAR Tomography. In Proc. of EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar, 2006. Keyword(s): SAR Processing, SAR Tomography, Tomography, Time-Domain Beamforming, Phase Calibration, Baseline Calibration, Tomographic Baseline Calibration, Airborne SAR, E-SAR.
 Abstract: Interest on 3D imaging in a remote sensing frame has grown in the recent years and it finds in SAR Tomography (TomSAR) a natural way to resolve for targets in the third dimension. In this paper we compare the performance of a pure beamforming technique with the SpecAn algorithm. This comparison has the goal to estabilish if the time domain beamforming (TDB) performance are efficient in order to perform tomographic focusing. A tomographic baseline calibration is also presented. The TDB is applied on simulated and real airborne data in L-band. The real data have been acquired during a tomographic campaign in May 1998 on the test site of Oberpfaffenhofen (Germany) with the E-SAR system of the German Aerospace Center (DLR).

@InProceedings{nanniniScheiber06:TimeDomainTomo,
Title = {A Time Domain Beamforming Algorithm for SAR Tomography},
Author = {Matteo Nannini and Rolf Scheiber},
Booktitle = {Proc. of EUSAR 2006 - 6th European Conference on Synthetic Aperture Radar},
Url = {http://elib.dlr.de/43943/01/Nannini_A_Time_Domain_Beamforming_for_SAR_Tomography.pdf},
Year = {2006},
Abstract = {Interest on 3D imaging in a remote sensing frame has grown in the recent years and it finds in SAR Tomography (TomSAR) a natural way to resolve for targets in the third dimension. In this paper we compare the performance of a pure beamforming technique with the SpecAn algorithm. This comparison has the goal to estabilish if the time domain beamforming (TDB) performance are efficient in order to perform tomographic focusing. A tomographic baseline calibration is also presented. The TDB is applied on simulated and real airborne data in L-band. The real data have been acquired during a tomographic campaign in May 1998 on the test site of Oberpfaffenhofen (Germany) with the E-SAR system of the German Aerospace Center (DLR).},
Keywords = {SAR Processing, SAR Tomography, Tomography, Time-Domain Beamforming, Phase Calibration, Baseline Calibration, Tomographic Baseline Calibration, Airborne SAR, E-SAR},
Owner = {ofrey},
Pdf = {../../../docs/nanniniScheiberTomo06.pdf}
}


14. P. Prats, A. Reigber, Jordi J. Mallorqui, P. Blanco, and A. Moreira. Estimation of the Deformation Temporal Evolution Using Airborne Differential SAR Interferometry. In Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on, pages 1894-1897, July 2006. Keyword(s): SAR Processing, D-InSAR, ESAR, Airborne SAR, L-Band, differential interferometry, Interferometry, Motion Compensation, RME, Residual Motion Errors, deformation measurement.
@InProceedings{PratsReigberMallorquiBlancoMoreira2006a:DInSAR,
Title = {Estimation of the Deformation Temporal Evolution Using Airborne Differential SAR Interferometry},
Author = {Prats, P. and Reigber, A. and Mallorqui, Jordi J. and Blanco, P. and Moreira, A.},
Booktitle = {Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on},
Month = jul,
Pages = {1894--1897},
Url = {http://ieeexplore.ieee.org/iel5/4087812/4241146/04241636.pdf},
Year = {2006},
Keywords = {SAR Processing, D-InSAR, ESAR, Airborne SAR, L-Band, differential interferometry, Interferometry, Motion Compensation, RME, Residual Motion Errors, deformation measurement},
Owner = {ofrey},
Pdf = {../../../docs/PratsReigberMallorquiBlancoMoreira2006a.pdf}
}


15. Brian D. Rigling. Multistage entropy minimization for SAR image autofocus. In Edmund G. Zelnio and Frederick D. Garber, editors, Algorithms for Synthetic Aperture Radar Imagery XIII, volume 6237, pages 150 - 159, 2006. International Society for Optics and Photonics, SPIE. Keyword(s): SAR Processing, SAR, ground map, autofocus.
 Abstract: This paper discusses a multistage approach to entropy minimization for SAR image autofocus. The new algorithm is compared to existing approaches, including point based autofocus, sub-aperture based autofocus, and hybrid methods. Monte Carlo statistical results are presented for simulated clutter scenes and point target scenes. The new minimum entropy autofocus provides improved speed and accuracy in correcting azimuth phase errors in both scenarios.

@InProceedings{riglingSPIE2006MultiStageEntropyMinimizationSARImageAutofocus,
author = {Brian D. Rigling},
booktitle = {Algorithms for Synthetic Aperture Radar Imagery XIII},
title = {Multistage entropy minimization for {SAR} image autofocus},
year = {2006},
editor = {Edmund G. Zelnio and Frederick D. Garber},
organization = {International Society for Optics and Photonics},
pages = {150 -- 159},
publisher = {SPIE},
volume = {6237},
abstract = {This paper discusses a multistage approach to entropy minimization for SAR image autofocus. The new algorithm is compared to existing approaches, including point based autofocus, sub-aperture based autofocus, and hybrid methods. Monte Carlo statistical results are presented for simulated clutter scenes and point target scenes. The new minimum entropy autofocus provides improved speed and accuracy in correcting azimuth phase errors in both scenarios.},
doi = {10.1117/12.669957},
keywords = {SAR Processing, SAR, ground map, autofocus},
owner = {ofrey},
url = {https://doi.org/10.1117/12.669957},

}


16. J. Sanz-Marcos, Jordi J. Mallorqui, A. Aguasca, and P. Prats. First ENVISAT and ERS-2 Parasitic Bistatic Fixed Receiver SAR Images Processed with the Subaperture Range-Doppler Algorithm. In Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on, pages 1840-1843, August 2006.
@InProceedings{SanzMarcosMallorquiAguascaPrats2006:Bistatic,
Title = {First ENVISAT and ERS-2 Parasitic Bistatic Fixed Receiver SAR Images Processed with the Subaperture Range-Doppler Algorithm},
Author = {Sanz-Marcos, J. and Mallorqui, Jordi J. and Aguasca, A. and Prats, P.},
Booktitle = {Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on},
Month = aug,
Pages = {1840--1843},
Year = {2006},
Owner = {ofrey},
Timestamp = {2007.08.14}
}


17. H.P. Tran, F. Gumbmann, J. Weinzierl, and L.P. Schmidt. A Fast Scanning W-Band System for Advanced Millimetre-Wave Short Range Imaging Applications. In Proc. European Radar Conference, pages 146-149, September 2006. Keyword(s): SAR Processing, W-Band, broadband antennas, focusing, frequency response, millimetre wave antennas, millimetre wave imaging, millimetre wave measurement, radar antennas, radar imaging, scanning antennas, synthetic aperture radar, SAR, antenna, broadband frequency response, conical horn, dielectric lens, focused bistatic measurement setup, free space millimetre-wave imaging setup, planar test object, scanning W-band system, synthetic aperture radar algorithm, unfocused measurement setup, Antenna measurements, Costs, Dielectric losses, Dielectric measurements, Distortion measurement, Electromagnetic measurements, Focusing, Lenses, Microwave imaging, Thickness measurement.
 Abstract: The paper presents the development of a fast scanning W-Band (75-100 GHz) system and a suitable antenna concept for advanced imaging applications. The goal is to obtain a broadband frequency response from a large target area within a short time period. Two typical approaches for the design of a free space millimetre-wave imaging setup will be discussed. The first approach consists of a focused bistatic measurement setup that includes a combination of a conical horn and a dielectric lens in order to focus the beam. The basic idea of the second approach is to use an unfocused measurement setup employing synthetic aperture radar (SAR) algorithms in order to focus the image numerically. Both measurement setups will be discussed with respect to the capability for fast scanning mm-wave imaging systems. Experimental results on planar test objects demonstrate the performance of the developed W-Band system compared to a commercial vector network analyzer (VNA)

@INPROCEEDINGS{tranGumbmannWeinzierlSchmidtEURAD2006WBandRadar,
author={H.P. Tran and F. Gumbmann and J. Weinzierl and L.P. Schmidt},
title={A Fast Scanning W-Band System for Advanced Millimetre-Wave Short Range Imaging Applications},
year={2006},
volume={},
number={},
pages={146-149},
abstract={The paper presents the development of a fast scanning W-Band (75-100 GHz) system and a suitable antenna concept for advanced imaging applications. The goal is to obtain a broadband frequency response from a large target area within a short time period. Two typical approaches for the design of a free space millimetre-wave imaging setup will be discussed. The first approach consists of a focused bistatic measurement setup that includes a combination of a conical horn and a dielectric lens in order to focus the beam. The basic idea of the second approach is to use an unfocused measurement setup employing synthetic aperture radar (SAR) algorithms in order to focus the image numerically. Both measurement setups will be discussed with respect to the capability for fast scanning mm-wave imaging systems. Experimental results on planar test objects demonstrate the performance of the developed W-Band system compared to a commercial vector network analyzer (VNA)},
keywords={SAR Processing, W-Band,broadband antennas;focusing;frequency response;millimetre wave antennas;millimetre wave imaging;millimetre wave measurement;radar antennas;radar imaging;scanning antennas;synthetic aperture radar;SAR;antenna;broadband frequency response;conical horn;dielectric lens;focused bistatic measurement setup;free space millimetre-wave imaging setup;planar test object;scanning W-band system;synthetic aperture radar algorithm;unfocused measurement setup;Antenna measurements;Costs;Dielectric losses;Dielectric measurements;Distortion measurement;Electromagnetic measurements;Focusing;Lenses;Microwave imaging;Thickness measurement},
ISSN={},
month=sep,
owner = {ofrey},

}


18. U. Wegmuller, C. Werner, T. Strozzi, and A. Wiesmann. Ionospheric Electron Concentration Effects on SAR and INSAR. In 2006 IEEE International Symposium on Geoscience and Remote Sensing, pages 3731-3734, July 2006. Keyword(s): SAR Processing, Ionosphere, Ionospheric Path Delay, TEC, Azimuth, Earth, Electrons, Frequency, Ionosphere, L-band, Layout, Synthetic aperture radar, Synthetic aperture radar interferometry, Tracking.
@InProceedings{wegmullerWernerStrozziWiesmannIGARSS2006SARIonospericTEC,
author = {U. Wegmuller and C. Werner and T. Strozzi and A. Wiesmann},
title = {Ionospheric Electron Concentration Effects on SAR and INSAR},
booktitle = {2006 IEEE International Symposium on Geoscience and Remote Sensing},
year = {2006},
pages = {3731-3734},
month = jul,
issn = {2153-6996},
keywords = {SAR Processing, Ionosphere, Ionospheric Path Delay, TEC, Azimuth;Earth;Electrons;Frequency;Ionosphere;L-band;Layout;Synthetic aperture radar;Synthetic aperture radar interferometry;Tracking},
owner = {ofrey},

}


19. D. Yocky and D. Wahl. Minimum-Latency Polar Format Algorithm. In Proc. IEEE Int. Geosci. Remote Sens. Symposium, pages 3177-3179, July 2006. Keyword(s): SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA.
 Abstract: The polar format algorithm (PFA) is a computationally efficient image formation method for high-resolution spotlight-mode SAR data collections. Yet, its usual real-time implementation waits until the entire synthetic aperture has been collected before beginning image formation. This results in a latency time. This paper presents a new approach to PFA that performs range and azimuth interpolation and range compression as the aperture is collected. Thus, the remaining latency is approximately the azimuth compression time. Performing image formation during aperture collection makes minimum-latency PFA a viable real-time image formation algorithm.

@InProceedings{yockyWahlIEEE2006:RealTimePolarFormat,
Title = {Minimum-Latency Polar Format Algorithm},
Author = {Yocky, D. and Wahl, D.},
Booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symposium},
Month = jul,
Pages = {3177-3179},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4241964},
Year = {2006},
Abstract = {The polar format algorithm (PFA) is a computationally efficient image formation method for high-resolution spotlight-mode SAR data collections. Yet, its usual real-time implementation waits until the entire synthetic aperture has been collected before beginning image formation. This results in a latency time. This paper presents a new approach to PFA that performs range and azimuth interpolation and range compression as the aperture is collected. Thus, the remaining latency is approximately the azimuth compression time. Performing image formation during aperture collection makes minimum-latency PFA a viable real-time image formation algorithm.},
Keywords = {SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA},
Owner = {ofrey},
Pdf = {../../../docs/yockyWahlIEEE2006.pdf}
}


20. D. Yocky, D. Wahl, and C. V. Jakowatz Jr.. Spotlight-Mode SAR Image Formation Utilizing the Chirp Z-Transform in Two Dimensions. In Proc. IEEE Int. Geosci. Remote Sens. Symposium, pages 4180-4182, July 2006. Keyword(s): SAR Processing, SPECAN-like Processing, SPECAN, Chirp-Z Transform, Chirp-Z Transform-based Focusing, Spotlight SAR, Spotlight-mode data.
 Abstract: A new spotlight-mode synthetic aperture radar image formation approach is presented that directly utilizes the reflected electromagnetic returns collected on a polar grid. This approach eliminates polar-to-rectangular grid interpolation by employing chirp z-transforms in two dimensions. Since the chirp z-transform can be implemented via fast Fourier transforms (FFTs), this image formation algorithm consists almost entirely of FFTs allowing it to exploit computationally-efficient FFT engines for fast image formation speeds. This paper presents the algorithm, and compares the operation counts and execution time between the new algorithm and traditional polar formatting, which employs interpolation. The paper also presents conditions for which the chirp z-transform in two dimensions is advantageous.

@InProceedings{yockyWahlJakowatzSpotlightChirpZIEEE2006,
author = {Yocky, D. and Wahl, D. and Jakowatz Jr., C. V.},
title = {Spotlight-Mode SAR Image Formation Utilizing the Chirp Z-Transform in Two Dimensions},
booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symposium},
year = {2006},
pages = {4180-4182},
month = jul,
abstract = {A new spotlight-mode synthetic aperture radar image formation approach is presented that directly utilizes the reflected electromagnetic returns collected on a polar grid. This approach eliminates polar-to-rectangular grid interpolation by employing chirp z-transforms in two dimensions. Since the chirp z-transform can be implemented via fast Fourier transforms (FFTs), this image formation algorithm consists almost entirely of FFTs allowing it to exploit computationally-efficient FFT engines for fast image formation speeds. This paper presents the algorithm, and compares the operation counts and execution time between the new algorithm and traditional polar formatting, which employs interpolation. The paper also presents conditions for which the chirp z-transform in two dimensions is advantageous.},
file = {:yockyWahlJakowatzSpotlightChirpZIEEE2006.pdf:PDF},
keywords = {SAR Processing, SPECAN-like Processing, SPECAN, Chirp-Z Transform, Chirp-Z Transform-based Focusing, Spotlight SAR, Spotlight-mode data},
owner = {ofrey},
pdf = {../../../docs/yockyWahlJakowatzSpotlightChirpZIEEE2006.pdf},
url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4242220},

}


21. E.C. Zaugg, D.L. Hudson, and D.G. Long. The BYU SAR: A Small, Student-Built SAR for UAV Operation. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 411-414, July 2006. Keyword(s): SAR Processing, BYU SAR, UAV.
@InProceedings{Zaugg2006,
author = {Zaugg, E.C. and Hudson, D.L. and Long, D.G.},
booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
title = {The {BYU} SAR: A Small, Student-Built {SAR} for {UAV} Operation},
year = {2006},
month = jul,
pages = {411--414},
keywords = {SAR Processing, BYU SAR, UAV},
owner = {ofrey},

}


22. X. Zheng, W. Yu, and Z. Li. A Novel Algorithm for Wide Beam SAR Motion Compensation Based on Frequency Division. In IEEE International Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006., pages 3160-3163, August 2006. Keyword(s): SAR Processing, Motion Compensation, MoComp, P-Band, Wide Beamwidth, Airborne SAR, Frequency Division, Frequency-Division Motion Compensation, FD-MOCO.
 Abstract: This paper proposes a novel motion compensation algorithm for wide beam Synthetic Aperture Radar (SAR) based on frequency division. It applies motion compensation in time domain and corrects both low- and high- frequency motion errors. The rationale and procedure of this algorithm are introduced in detail. Point scatterers of a P-band airborne SAR with different motion errors are tested to validate this algorithm. Compared with traditional narrow beam motion compensation and available wide beam compensation, the proposed algorithm has better performance.

@InProceedings{zhengYuLi2006:MoComp,
Title = {{A Novel Algorithm for Wide Beam SAR Motion Compensation Based on Frequency Division}},
Author = {Zheng, X. and Yu, W. and Li, Z.},
Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006.},
Month = {aug},
Pages = {3160-3163},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4241959&isnumber=4241146},
Year = {2006},
Abstract = {This paper proposes a novel motion compensation algorithm for wide beam Synthetic Aperture Radar (SAR) based on frequency division. It applies motion compensation in time domain and corrects both low- and high- frequency motion errors. The rationale and procedure of this algorithm are introduced in detail. Point scatterers of a P-band airborne SAR with different motion errors are tested to validate this algorithm. Compared with traditional narrow beam motion compensation and available wide beam compensation, the proposed algorithm has better performance.},
Keywords = {SAR Processing, Motion Compensation, MoComp, P-Band, Wide Beamwidth, Airborne SAR, Frequency Division, Frequency-Division Motion Compensation, FD-MOCO},
Owner = {ofrey},
Pdf = {../../../docs/zhengYuLi2006.pdf}
}


### Internal reports

1. Mehrdad Soumekh. Time Domain Non-Linear SAR Processing. Technical report, Department of Electrical Engineering,State University of New York, 2006. Keyword(s): SAR Processing, Back-Projection, Time-Domain Back-Projection, TDBP, Non-Linear Flight Path, Matlab, MPI, MatlabMPI, Video SAR, Parallel Processing, Wavefront Reconstruction, omega-k Algorithm, omega-k, Range Migration Algorithm.
@TechReport{soumekhReport2006:TDBP,
title = {Time Domain Non-Linear SAR Processing},
institution = {Department of Electrical Engineering,State University of New York},
year = {2006},
keywords = {SAR Processing, Back-Projection, Time-Domain Back-Projection, TDBP, Non-Linear Flight Path, Matlab, MPI, MatlabMPI, Video SAR, Parallel Processing,Wavefront Reconstruction, omega-k Algorithm, omega-k,Range Migration Algorithm},
owner = {ofrey},
pdf = {../../../docs/soumekhNonLinSARReport2006.pdf},

}


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This collection of SAR literature is far from being complete.
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