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Publications of year 2004

Books and proceedings

  1. Eugene F. Knott, John F. Shaeffer, and Michael T. Tuley. Radar Cross Section (2nd Edition). 2004. Keyword(s): radar cross section, RCS, electromagnetic wave absorption, radar cross-sections, electromagnetic wave scattering, scattering mechanisms, complex body, radar cross section reduction methods, test targets, techniques for measuring absorber property, RCS prediction techniques, background information, simple body, scattering characteristics, RCS behavior, electromagnetic wave propagation, electromagnetic waves theory, Radar theory.
    Abstract: Radar cross section (RCS) is a comparison of two radar signal strengths. One is the strength of the radar beam sweeping over a target, the other is the strength of the reflected echo sensed by the receiver. This book shows how the RCS gauge can be predicted for theoretical objects and how it can be measured for real targets. Predicting RCS is not easy, even for simple objects like spheres or cylinders, but this book explains the two exact forms of theory so well that even a novice will understand enough to make close predictions. Weapons systems developers are keenly interested in reducing the RCS of their platforms. The two most practical ways to reduce RCS are shaping and absorption. This book explains both in great detail, especially in the design, evaluation, and selection of radar absorbers. There is also great detail on the design and employment of indoor and outdoor test ranges for scale models or for full-scale targets (such as aircraft). In essence, this book covers everything you need to know about RCS, from what it is, how to predict and measure, and how to test targets (indoors and out), and how to beat it.

    @Book{knottShaefferTuleyBook2004RadarCrossSection,
    author = {Eugene F. Knott and John F. Shaeffer and Michael T. Tuley},
    title = {Radar Cross Section (2nd Edition)},
    year = {2004},
    doi = {10.1049/SBRA026E},
    abstract = {Radar cross section (RCS) is a comparison of two radar signal strengths. One is the strength of the radar beam sweeping over a target, the other is the strength of the reflected echo sensed by the receiver. This book shows how the RCS gauge can be predicted for theoretical objects and how it can be measured for real targets. Predicting RCS is not easy, even for simple objects like spheres or cylinders, but this book explains the two exact forms of theory so well that even a novice will understand enough to make close predictions. Weapons systems developers are keenly interested in reducing the RCS of their platforms. The two most practical ways to reduce RCS are shaping and absorption. This book explains both in great detail, especially in the design, evaluation, and selection of radar absorbers. There is also great detail on the design and employment of indoor and outdoor test ranges for scale models or for full-scale targets (such as aircraft). In essence, this book covers everything you need to know about RCS, from what it is, how to predict and measure, and how to test targets (indoors and out), and how to beat it.},
    keywords = {radar cross section,RCS,electromagnetic wave absorption,radar cross-sections,electromagnetic wave scattering,scattering mechanisms,complex body,radar cross section reduction methods,test targets,techniques for measuring absorber property,RCS prediction techniques,background information,simple body,scattering characteristics,RCS behavior,electromagnetic wave propagation,electromagnetic waves theory,Radar theory},
    owner = {ofrey},
    
    }
    


Articles in journal or book chapters

  1. Urs Wegmuller, Charles L. Werner, Tazio Strozzi, and Andreas Wiesmann. Multi-temporal interferometric point target analysis. In Paul Smits and Lorenzo Bruzzone, editors, Analysis of multi-temporal remote sensing images, volume 3 of Series in Remote Sensing, pages 136-144. World Scientific, 2004. Keyword(s): SAR Processing, SAR Interferometry, InSAR, Persistent Scatterer Interferometry, PSI, Interferometric Point Target Analysis, IPTA.
    Abstract: Interferometric Point Target Analysis (IPTA) is a method to exploit the temporal and spatial characteristics of interferometric signatures collected from point targets to accurately map surface deformation histories, terrain heights, and relative atmospheric path delays. In this contribution the IPTA methodology is presented. Furthermore, based on examples, its applicability for stacks of ERS and JERS SAR data is validated.

    @InCollection{wegmullerWernerStrozziWiesmannMultiTempBook2014IPTA,
    author = {Wegmuller, Urs and Werner, Charles L. and Strozzi, Tazio and Wiesmann, Andreas},
    title = {Multi-temporal interferometric point target analysis},
    booktitle = {Analysis of multi-temporal remote sensing images},
    publisher = {World Scientific},
    year = {2004},
    editor = {Smits, Paul and Bruzzone, Lorenzo},
    volume = {3},
    series = {Series in Remote Sensing},
    pages = {136-144},
    isbn = {978-981-4482-34-9},
    abstract = {Interferometric Point Target Analysis (IPTA) is a method to exploit the temporal and spatial characteristics of interferometric signatures collected from point targets to accurately map surface deformation histories, terrain heights, and relative atmospheric path delays. In this contribution the IPTA methodology is presented. Furthermore, based on examples, its applicability for stacks of ERS and JERS SAR data is validated.},
    doi = {10.1142/9789812702630_0015},
    file = {:wegmullerWernerStrozziWiesmannMultiTempBook2014IPTA.pdf:PDF},
    keywords = {SAR Processing, SAR Interferometry, InSAR, Persistent Scatterer Interferometry, PSI, Interferometric Point Target Analysis, IPTA},
    owner = {ofrey},
    
    }
    


  2. Sune R.J. Axelsson. Beam characteristics of three-dimensional SAR in curved or random paths. IEEE Trans. Geosci. Remote Sens., 42(10):2324-2334, Oct. 2004. Keyword(s): SAR Processing, SAR Tomography, Tomography, Non-Linear Flight Path, Non-linear SAR.
    Abstract: Interferometric synthetic aperture radar (InSAR) provides average height information by combining data from two parallel paths. True three-dimensional (3-D) SAR also detects the height distribution, which is of significant interest in airborne reconnaissance, forest inventory, and subsurface or wall-penetrating sensing applications as examples. In this paper, the beam performance of 3-D SAR is studied and compared for different curved line paths, such as circles, ellipses, and spirals ending up with random sampling. Curved path geometry reduces the ambiguity in height angle of traditional multipass SAR, and random path variation further improves the sidelobe suppression. The poor sidelobe suppression of a single circle path is significantly improved in near-range geometry in combination with high range resolution. By introducing a window function dependent on focus point and path position, high sidelobe suppression was achieved in an extended ground area below the circle path.

    @Article{Axelsson2004a,
    Title = {Beam characteristics of three-dimensional {SAR} in curved or random paths},
    Author = {Axelsson, Sune R.J.},
    Doi = {10.1109/TGRS.2004.834802},
    Month = {Oct.},
    Number = {10},
    Pages = {2324--2334},
    Url = {http://ieeexplore.ieee.org/iel5/36/29599/01344182.pdf},
    Volume = {42},
    Year = {2004},
    Abstract = {Interferometric synthetic aperture radar (InSAR) provides average height information by combining data from two parallel paths. True three-dimensional (3-D) SAR also detects the height distribution, which is of significant interest in airborne reconnaissance, forest inventory, and subsurface or wall-penetrating sensing applications as examples. In this paper, the beam performance of 3-D SAR is studied and compared for different curved line paths, such as circles, ellipses, and spirals ending up with random sampling. Curved path geometry reduces the ambiguity in height angle of traditional multipass SAR, and random path variation further improves the sidelobe suppression. The poor sidelobe suppression of a single circle path is significantly improved in near-range geometry in combination with high range resolution. By introducing a window function dependent on focus point and path position, high sidelobe suppression was achieved in an extended ground area below the circle path.},
    
    
     Journal = {IEEE Trans. Geosci. Remote Sens.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, Non-Linear Flight Path, Non-linear SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/axelsson04Tomo.pdf} 
    }
    


  3. Ciro Cafforio, Pietro Guccione, and Andrea Monti-Guarnieri. Doppler Centroid Estimation for ScanSAR Data. IEEE Transactions on Geoscience and Remote Sensing, 42(1):14-23, January 2004. Keyword(s): SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Clutterlock, Satellite SAR, RADARSAT 1, ENVISAT, ScanSAR.
    Abstract: We introduce a novel accurate technique to estimate the Doppler centroid (DC) in ScanSAR missions. The technique starts from the ambiguous DC measures in the subswaths and uses a method alternative to standard unwrapping to undo the jumps in estimates induced by modulo pulse repetition frequency (PRF) measures. The proposed alternative is less error prone than the usual unwrapping techniques. Doppler Ambiguity is then solved by implementing a maximum-likelihood estimate that exploits the different PRFs used in different subswaths. An azimuth pointing of the antenna that does not change with subswaths, or that changes in a known way, is assumed. However, if the PRF diversity is strong enough, unknown small changes in azimuth pointing are tolerated and accurately estimated. This estimator is much simpler and more efficient, than those in the literature. Results achieved with both RADARSAT 1 and ENVISAT ScanSAR data are reported.

    @Article{CaffGuccMonti04:Doppler,
    Title = {{Doppler Centroid Estimation for ScanSAR Data}},
    Author = {Ciro Cafforio and Pietro Guccione and Andrea Monti-Guarnieri},
    Month = Jan,
    Number = {1},
    Pages = {14-23},
    Volume = {42},
    Year = {2004},
    Abstract = {We introduce a novel accurate technique to estimate the Doppler centroid (DC) in ScanSAR missions. The technique starts from the ambiguous DC measures in the subswaths and uses a method alternative to standard unwrapping to undo the jumps in estimates induced by modulo pulse repetition frequency (PRF) measures. The proposed alternative is less error prone than the usual unwrapping techniques. Doppler Ambiguity is then solved by implementing a maximum-likelihood estimate that exploits the different PRFs used in different subswaths. An azimuth pointing of the antenna that does not change with subswaths, or that changes in a known way, is assumed. However, if the PRF diversity is strong enough, unknown small changes in azimuth pointing are tolerated and accurately estimated. This estimator is much simpler and more efficient, than those in the literature. Results achieved with both RADARSAT 1 and ENVISAT ScanSAR data are reported.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Clutterlock, Satellite SAR, RADARSAT 1, ENVISAT, ScanSAR},
    Pdf = {../../../docs/cafforioGuccioneGuarnieri04.pdf} 
    }
    


  4. Boon Leng Cheong, Michael W. Hoffman, Robert D. Palmer, Stephen J. Frasier, and F. J. López-Dekker. Pulse pair beamforming and the effects of reflectivity field variations on imaging radars. Radio Science, 39(3), 2004. Note: RS3014. Keyword(s): Radio Science: Remote sensing, Radio Science: Signal processing, Radio Science: Tomography and imaging, Radio Science: Instruments and techniques, pulse pair beamforming, gradient variations, imaging radars.
    Abstract: Coherent radar imaging (CRI), which is fundamentally a beamforming process, has been used to create images of microscale, reflectivity structures within the resolution volume of atmospheric Doppler radars. This powerful technique has the potential to unlock many new discoveries in atmospheric studies. The Turbulent Eddy Profiler (TEP) is a unique 915 MHz boundary layer radar consisting of a maximum of 91 independent receivers. The TEP configuration allows sophisticated CRI algorithms to be implemented providing significant improvement in angular resolution. The present work includes a thorough simulation study of some of the capabilities of the TEP system. The pulse pair processor, used for radial velocity and spectral width estimation with meteorological radars, is combined with beamforming technique, in an efficient manner, to the imaging radar case. By numerical simulation the new technique is shown to provide robust and computationally efficient estimates of the spectral moments. For this study, a recently developed atmospheric radar simulation method is employed that uses the ten thousand scattering points necessary for the high resolution imaging simulation. Previous methods were limited in the number of scatterers due to complexity issues. Radial velocity images from the beamforming radar are used to estimate the three-dimensional wind field map within the resolution volume. It is shown that a large root mean square (RMS) error in imputed three-dimensional wind fields can occur using standard Fourier imaging. This RMS error does not improve even as SNR is increased. The cause of the error is reflectivity variations within the resolution volume. The finite beamwidth of the beamformer skews the radial velocity estimate, and this results in poor wind field estimates. Adaptive Capon beamforming consistently outperforms the Fourier method in the quantitative study and has been demonstrated to enhance the performance compared to the Fourier method.

    @Article{CheongHoffmanPalmerFrasierLopezDekker2004,
    author = {Cheong, Boon Leng and Hoffman, Michael W. and Palmer, Robert D. and Frasier, Stephen J. and L\'opez-Dekker, F. J.},
    title = {Pulse pair beamforming and the effects of reflectivity field variations on imaging radars},
    journal = {Radio Science},
    year = {2004},
    volume = {39},
    number = {3},
    issn = {1944-799X},
    note = {RS3014},
    abstract = {Coherent radar imaging (CRI), which is fundamentally a beamforming process, has been used to create images of microscale, reflectivity structures within the resolution volume of atmospheric Doppler radars. This powerful technique has the potential to unlock many new discoveries in atmospheric studies. The Turbulent Eddy Profiler (TEP) is a unique 915 MHz boundary layer radar consisting of a maximum of 91 independent receivers. The TEP configuration allows sophisticated CRI algorithms to be implemented providing significant improvement in angular resolution. The present work includes a thorough simulation study of some of the capabilities of the TEP system. The pulse pair processor, used for radial velocity and spectral width estimation with meteorological radars, is combined with beamforming technique, in an efficient manner, to the imaging radar case. By numerical simulation the new technique is shown to provide robust and computationally efficient estimates of the spectral moments. For this study, a recently developed atmospheric radar simulation method is employed that uses the ten thousand scattering points necessary for the high resolution imaging simulation. Previous methods were limited in the number of scatterers due to complexity issues. Radial velocity images from the beamforming radar are used to estimate the three-dimensional wind field map within the resolution volume. It is shown that a large root mean square (RMS) error in imputed three-dimensional wind fields can occur using standard Fourier imaging. This RMS error does not improve even as SNR is increased. The cause of the error is reflectivity variations within the resolution volume. The finite beamwidth of the beamformer skews the radial velocity estimate, and this results in poor wind field estimates. Adaptive Capon beamforming consistently outperforms the Fourier method in the quantitative study and has been demonstrated to enhance the performance compared to the Fourier method.},
    doi = {10.1029/2002RS002843},
    file = {:CheongHoffmanPalmerFrasierLopezDekker2004.pdf:PDF},
    keywords = {Radio Science: Remote sensing, Radio Science: Signal processing, Radio Science: Tomography and imaging, Radio Science: Instruments and techniques, pulse pair beamforming, gradient variations, imaging radars},
    owner = {ofrey},
    pdf = {../../../docs/CheongHoffmanPalmerFrasierLopezDekker2004.pdf},
    url = {http://dx.doi.org/10.1029/2002RS002843},
    
    }
    


  5. Ian G. Cumming. A Spatially Selective Approach to Doppler Estimation for Frame-Based Satellite SAR Processing. IEEE Transactions on Geoscience and Remote Sensing, 42(6):1135-1148, June 2004. Keyword(s): SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Satellite SAR, Geometry Models, Quality Metrics, Global Surface Fit.
    Abstract: When Doppler centroid estimators are applied to satellite SAR data, biased estimates are often obtained because of anomalies in the received data. Typical anomalies include areas of low SNR, strong discrete targets and radiometric discontinuities. In this paper, a new method of Doppler centroid estimation is presented that takes advantage of principles such as spatial diversity, estimator quality checks, geometric models, and the fitting of a global estimate over a wide area of a SAR scene. In the proposed scheme, Doppler estimates are made over small blocks of data covering a whole frame, so that all parts of the scene are potentially represented. The quality of each block estimate is examined using data statistics or estimator quality measures. Poor estimates are rejected, and the remaining estimates are used to fit a surface model of the Doppler centroid versus the range and azimuth extent of the scene. A physical model that relates the satellite's orbit, attitude and beam-pointing-direction to the Doppler centroid is used to get realistic surface fits and to reduce the complexity (dimensionality) of the estimation problem. The method is tested with RADARSAT-1 and Shuttle Radar Topography Mission X-band SAR (SRTM/X-SAR) spaceborne data and is found to work well with scenes that do have radiometric anomalies, and in scenes where attitude adjustments cause the Doppler to change rapidly.

    @Article{Cumming04:DopCentrEst,
    Title = {{A Spatially Selective Approach to Doppler Estimation for Frame-Based Satellite SAR Processing}},
    Author = {Ian G. Cumming},
    Month = Jun,
    Number = {6},
    Pages = {1135-1148},
    Url = {http://ieeexplore.ieee.org/iel5/36/28983/01304880.pdf},
    Volume = {42},
    Year = {2004},
    Abstract = {When Doppler centroid estimators are applied to satellite SAR data, biased estimates are often obtained because of anomalies in the received data. Typical anomalies include areas of low SNR, strong discrete targets and radiometric discontinuities. In this paper, a new method of Doppler centroid estimation is presented that takes advantage of principles such as spatial diversity, estimator quality checks, geometric models, and the fitting of a global estimate over a wide area of a SAR scene. In the proposed scheme, Doppler estimates are made over small blocks of data covering a whole frame, so that all parts of the scene are potentially represented. The quality of each block estimate is examined using data statistics or estimator quality measures. Poor estimates are rejected, and the remaining estimates are used to fit a surface model of the Doppler centroid versus the range and azimuth extent of the scene. A physical model that relates the satellite's orbit, attitude and beam-pointing-direction to the Doppler centroid is used to get realistic surface fits and to reduce the complexity (dimensionality) of the estimation problem. The method is tested with RADARSAT-1 and Shuttle Radar Topography Mission X-band SAR (SRTM/X-SAR) spaceborne data and is found to work well with scenes that do have radiometric anomalies, and in scenes where attitude adjustments cause the Doppler to change rapidly.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Satellite SAR, Geometry Models, Quality Metrics, Global Surface Fit},
    Pdf = {../../../docs/CumDoppler04.pdf} 
    }
    


  6. Knut Eldhuset. Ultra high resolution spaceborne SAR processing. Aerospace and Electronic Systems, IEEE Transactions on, 40(1):370-378, 2004. Keyword(s): SAR Processing, radar signal processing, spaceborne radar, synthetic aperture radar, transfer functions, EETF4, SAR geometry, X-band radar, azimuth signal accuracy requirements, erroneous Doppler parameters, fourth-order extended exact transfer function, spaceborne SAR processing, squint, synthetic aperture radar, ultra high resolution SAR.
    Abstract: The accuracy requirements of the azimuth signal for spaceborne synthetic aperture radar (SAR) processing is analysed. Degradations of simulated extended scenes and point targets are studied at high squint or if erroneous Doppler parameters are used. At a resolution less than 1 m for X-band it is shown that the azimuth signal for spaceborne SAR geometry should be used. It is found that the fourth-order extended exact transfer function (EETF4) is a good candidate for demanding SAR processing.

    @Article{eldhuset04:EETF4,
    Title = {Ultra high resolution spaceborne SAR processing},
    Author = {Eldhuset, Knut},
    Number = {1},
    Pages = {370--378},
    Url = {http://ieeexplore.ieee.org/iel5/7/28783/01292176.pdf},
    Volume = {40},
    Year = {2004},
    Abstract = {The accuracy requirements of the azimuth signal for spaceborne synthetic aperture radar (SAR) processing is analysed. Degradations of simulated extended scenes and point targets are studied at high squint or if erroneous Doppler parameters are used. At a resolution less than 1 m for X-band it is shown that the azimuth signal for spaceborne SAR geometry should be used. It is found that the fourth-order extended exact transfer function (EETF4) is a good candidate for demanding SAR processing.},
    Journal = {Aerospace and Electronic Systems, IEEE Transactions on},
    Keywords = {SAR Processing, radar signal processing, spaceborne radar, synthetic aperture radar, transfer functions, EETF4, SAR geometry, X-band radar, azimuth signal accuracy requirements, erroneous Doppler parameters, fourth-order extended exact transfer function, spaceborne SAR processing, squint, synthetic aperture radar, ultra high resolution SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/eldhuset04.pdf} 
    }
    


  7. Jos Groot. River dike deformation measurement with airborne SAR. IEEE Geosci. Remote Sens. Lett., 1(2):94-97, April 2004. Keyword(s): SAR Processing, DInSAR, repeat-pass interferometry, InSAR, SAR interferometry, deformation measurement, displacement, subsidence, airborne SAR, deformation, remote sensing by radar, rivers, synthetic aperture radar, 5.5 day, airborne SAR, deformation measurement, interferometry, reflector analysis, river dikes, synthetic aperture radar, water levels, Atmospheric measurements, Interferometry, Levee, Radar tracking, Rivers, Synthetic aperture radar, Testing.
    Abstract: Due to extremely high water levels or extremely dry periods, river dikes can deform and eventually burst. The deformation can be measured with repeat-pass synthetic aperture radar (SAR) interferometry. Two flights (5.5-day interval) with an airborne C-band SAR were carried out to verify a particular case. During the second flight, the dike was deliberately deformed. Interferogram analyses showed that the dike deformed by at most 2 mm on this day, in approximate agreement with tachymeter measurements. Corner reflector analysis showed a deformation of about 1 cm during the 5.5-day interval, in good agreement with ground measurements.

    @Article{grootGRSL2004DikeDInSAR,
    author = {Groot, Jos},
    title = {River dike deformation measurement with airborne SAR},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    year = {2004},
    volume = {1},
    number = {2},
    pages = {94-97},
    month = apr,
    issn = {1545-598X},
    abstract = {Due to extremely high water levels or extremely dry periods, river dikes can deform and eventually burst. The deformation can be measured with repeat-pass synthetic aperture radar (SAR) interferometry. Two flights (5.5-day interval) with an airborne C-band SAR were carried out to verify a particular case. During the second flight, the dike was deliberately deformed. Interferogram analyses showed that the dike deformed by at most 2 mm on this day, in approximate agreement with tachymeter measurements. Corner reflector analysis showed a deformation of about 1 cm during the 5.5-day interval, in good agreement with ground measurements.},
    doi = {10.1109/LGRS.2004.824743},
    file = {:grootGRSL2004DikeDInSAR.pdf:PDF},
    keywords = {SAR Processing, DInSAR, repeat-pass interferometry, InSAR, SAR interferometry, deformation measurement, displacement, subsidence, airborne SAR;deformation;remote sensing by radar;rivers;synthetic aperture radar;5.5 day;airborne SAR;deformation measurement;interferometry; reflector analysis;river dikes;synthetic aperture radar;water levels;Atmospheric measurements; Interferometry;Levee;Radar tracking;Rivers;Synthetic aperture radar;Testing},
    pdf = {../../../docs/grootGRSL2004DikeDInSAR.pdf},
    
    }
    


  8. Andrew Hooper, Howard Zebker, Paul Segall, and Bert Kampes. A new method for measuring deformation on volcanoes and other natural terrains using InSAR persistent scatterers. Geophysical research letters, 31(23), 2004.
    @Article{hooperZebkerSegallKampesGRL2004DINSARPSIVolcanoDef,
    author = {Hooper, Andrew and Zebker, Howard and Segall, Paul and Kampes, Bert},
    title = {A new method for measuring deformation on volcanoes and other natural terrains using {InSAR} persistent scatterers},
    journal = {Geophysical research letters},
    year = {2004},
    volume = {31},
    number = {23},
    owner = {ofrey},
    publisher = {Wiley Online Library},
    
    }
    


  9. Bert M. Kampes and Ramon F. Hanssen. Ambiguity resolution for permanent scatterer interferometry. IEEE Trans. Geosci. Remote Sens., 42(11):2446-2453, November 2004. Keyword(s): LAMBDA method, ambiguity decorrelation, ambiguity resolution, bootstrap estimation, carrier phase observations, global positioning systems, integer least squares estimation, multivariate normal distribution, nonlinear parameter inversion algorithm, permanent scatterer interferometry, phase cycle ambiguity estimation, synthetic aperture radar interferometry, system of equations, variance-covariance matrix, geophysical signal processing, least squares approximations, normal distribution, parameter estimation, radiowave interferometry, remote sensing, remote sensing by radar, synthetic aperture radar;.
    Abstract: In the permanent scatterer technique of synthetic aperture radar interferometry, there is a need for an efficient and reliable nonlinear parameter inversion algorithm that includes estimation of the phase cycle ambiguities. Present techniques make use of a direct search of the solution space, treating the observations as deterministic and equally weighted, and which do not yield an exact solution. Moreover, they do not describe the quality of the estimated parameters. Here, we use the integer least squares estimator, which has the highest probability of correct integer estimation for problems with a multivariate normal distribution. With this estimator, the propagated variance-covariance matrix of the estimated parameters can be obtained. We have adapted the LAMBDA method, part of an integer least squares estimator developed for the ambiguity resolution of carrier phase observations in global positioning systems, to the problem of permanent scatterers. Key elements of the proposed method are the introduction of pseudo-observations to regularize the system of equations, decorrelation of the ambiguities for an efficient estimation, and the combination of a bootstrap estimator with an integer least squares search to obtain the final integer estimates. The performance of the proposed algorithm is demonstrated using simulated and real data.

    @Article{kampesHanssen2004PSI,
    author = {Kampes, Bert M. and Hanssen, Ramon F.},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    title = {Ambiguity resolution for permanent scatterer interferometry},
    year = {2004},
    issn = {0196-2892},
    month = nov,
    number = {11},
    pages = {2446-2453},
    volume = {42},
    abstract = {In the permanent scatterer technique of synthetic aperture radar interferometry, there is a need for an efficient and reliable nonlinear parameter inversion algorithm that includes estimation of the phase cycle ambiguities. Present techniques make use of a direct search of the solution space, treating the observations as deterministic and equally weighted, and which do not yield an exact solution. Moreover, they do not describe the quality of the estimated parameters. Here, we use the integer least squares estimator, which has the highest probability of correct integer estimation for problems with a multivariate normal distribution. With this estimator, the propagated variance-covariance matrix of the estimated parameters can be obtained. We have adapted the LAMBDA method, part of an integer least squares estimator developed for the ambiguity resolution of carrier phase observations in global positioning systems, to the problem of permanent scatterers. Key elements of the proposed method are the introduction of pseudo-observations to regularize the system of equations, decorrelation of the ambiguities for an efficient estimation, and the combination of a bootstrap estimator with an integer least squares search to obtain the final integer estimates. The performance of the proposed algorithm is demonstrated using simulated and real data.},
    doi = {10.1109/TGRS.2004.835222},
    keywords = {LAMBDA method; ambiguity decorrelation; ambiguity resolution; bootstrap estimation; carrier phase observations; global positioning systems; integer least squares estimation; multivariate normal distribution; nonlinear parameter inversion algorithm; permanent scatterer interferometry; phase cycle ambiguity estimation; synthetic aperture radar interferometry; system of equations; variance-covariance matrix; geophysical signal processing; least squares approximations; normal distribution; parameter estimation; radiowave interferometry; remote sensing; remote sensing by radar; synthetic aperture radar;},
    
    }
    


  10. R. Lanari, O. Mora, M. Manunta, J. J. Mallorqui, P. Berardino, and E. Sansosti. A small-baseline approach for investigating deformations on full-resolution differential SAR interferograms. IEEE Trans. Geosci. Remote Sens., 42(7):1377-1386, July 2004. Keyword(s): radar resolution, radiowave interferometry, remote sensing by radar, singular value decomposition, synthetic aperture radar, terrain mapping, topography (Earth), DIFSAR interferograms, European Remote Sensing satellites, atmospheric phase artifacts, differential SAR interferometry, digital elevation model, geodetic measurements, ground deformation, large-scale deformations, multilook data, residual phase components, single-look data, singular value decomposition, small-baseline subset, spatial resolutions, synthetic aperture radar, temporal evolution, topographic errors, Buildings, Digital elevation models, Interferometry, Large-scale systems, Phase detection, Phase estimation, Singular value decomposition, Spatial resolution, Synthetic aperture radar, Testing, Ground deformations, SAR, SAR interferometry, synthetic aperture radar.
    Abstract: This paper presents a differential synthetic aperture radar (SAR) interferometry (DIFSAR) approach for investigating deformation phenomena on full-resolution DIFSAR interferograms. In particular, our algorithm extends the capability of the small-baseline subset (SBAS) technique that relies on small-baseline DIFSAR interferograms only and is mainly focused on investigating large-scale deformations with spatial resolutions of about 100×100 m. The proposed technique is implemented by using two different sets of data generated at low (multilook data) and full (single-look data) spatial resolution, respectively. The former is used to identify and estimate, via the conventional SBAS technique, large spatial scale deformation patterns, topographic errors in the available digital elevation model, and possible atmospheric phase artifacts; the latter allows us to detect, on the full-resolution residual phase components, structures highly coherent over time (buildings, rocks, lava, structures, etc.), as well as their height and displacements. In particular, the estimation of the temporal evolution of these local deformations is easily implemented by applying the singular value decomposition technique. The proposed algorithm has been tested with data acquired by the European Remote Sensing satellites relative to the Campania area (Italy) and validated by using geodetic measurements.

    @ARTICLE{lanariMoraManuntaMallorquiBerardinoSansosti2004TGRSSBASFullResDInSAR,
    author={R. Lanari and O. Mora and M. Manunta and J. J. Mallorqui and P. Berardino and E. Sansosti},
    journal={IEEE Trans. Geosci. Remote Sens.},
    title={A small-baseline approach for investigating deformations on full-resolution differential {SAR} interferograms},
    year={2004},
    volume={42},
    number={7},
    pages={1377-1386},
    abstract={This paper presents a differential synthetic aperture radar (SAR) interferometry (DIFSAR) approach for investigating deformation phenomena on full-resolution DIFSAR interferograms. In particular, our algorithm extends the capability of the small-baseline subset (SBAS) technique that relies on small-baseline DIFSAR interferograms only and is mainly focused on investigating large-scale deformations with spatial resolutions of about 100×100 m. The proposed technique is implemented by using two different sets of data generated at low (multilook data) and full (single-look data) spatial resolution, respectively. The former is used to identify and estimate, via the conventional SBAS technique, large spatial scale deformation patterns, topographic errors in the available digital elevation model, and possible atmospheric phase artifacts; the latter allows us to detect, on the full-resolution residual phase components, structures highly coherent over time (buildings, rocks, lava, structures, etc.), as well as their height and displacements. In particular, the estimation of the temporal evolution of these local deformations is easily implemented by applying the singular value decomposition technique. The proposed algorithm has been tested with data acquired by the European Remote Sensing satellites relative to the Campania area (Italy) and validated by using geodetic measurements.},
    keywords={radar resolution;radiowave interferometry;remote sensing by radar;singular value decomposition;synthetic aperture radar;terrain mapping;topography (Earth);DIFSAR interferograms;European Remote Sensing satellites;atmospheric phase artifacts;differential SAR interferometry;digital elevation model;geodetic measurements;ground deformation;large-scale deformations;multilook data;residual phase components;single-look data;singular value decomposition;small-baseline subset;spatial resolutions;synthetic aperture radar;temporal evolution;topographic errors;Buildings;Digital elevation models;Interferometry;Large-scale systems;Phase detection;Phase estimation;Singular value decomposition;Spatial resolution;Synthetic aperture radar;Testing;Ground deformations;SAR;SAR interferometry;synthetic aperture radar},
    doi={10.1109/TGRS.2004.828196},
    ISSN={0196-2892},
    month=jul,
    
    }
    


  11. F. Lombardini, F. Bordoni, F. Gini, and L. Verrazzani. Multibaseline ATI-SAR for robust ocean surface velocity estimation. IEEE Transactions on Aerospace and Electronic Systems, 40(2):417-433, April 2004. Keyword(s): Bragg frequency, Bragg scatterers, Doppler centroid measurements, Doppler resolution, MB estimators, along-track interferometry, multibaseline ATI-SAR, ocean surface currents, robust data inversion, robust ocean surface velocity estimation, scatterer propagation velocity, synthetic aperture radar, wind direction, Doppler radar, Doppler shift, oceanographic techniques, radiowave interferometry, remote sensing by radar, synthetic aperture radar;.
    Abstract: An open problem of along-track interferometry (ATI) for synthetic aperture radar (SAR) sensing of ocean surface currents is the need of ancillary wind information for inversion of Doppler centroid measurements, that have to be compensated for the propagation velocity of advancing and/or receding Bragg scatterers. We propose three classes of estimators which exploit multibaseline (MB) ATI acquisition and Doppler resolution for robust data inversion under different degrees of a priori information about the wind direction and the value of the characteristic Bragg frequency. Performance analysis and comparison with conventional ATI show that the proposed MB estimators can produce accurate velocity estimates in the absence of detailed ancillary data.

    @Article{lombardiniBordoniGiniVerrazzani2004,
    author = {Lombardini, F. and Bordoni, F. and Gini, F. and Verrazzani, L.},
    journal = {IEEE Transactions on Aerospace and Electronic Systems},
    title = {Multibaseline {ATI-SAR} for robust ocean surface velocity estimation},
    year = {2004},
    issn = {0018-9251},
    month = apr,
    number = {2},
    pages = {417-433},
    volume = {40},
    abstract = {An open problem of along-track interferometry (ATI) for synthetic aperture radar (SAR) sensing of ocean surface currents is the need of ancillary wind information for inversion of Doppler centroid measurements, that have to be compensated for the propagation velocity of advancing and/or receding Bragg scatterers. We propose three classes of estimators which exploit multibaseline (MB) ATI acquisition and Doppler resolution for robust data inversion under different degrees of a priori information about the wind direction and the value of the characteristic Bragg frequency. Performance analysis and comparison with conventional ATI show that the proposed MB estimators can produce accurate velocity estimates in the absence of detailed ancillary data.},
    doi = {10.1109/TAES.2004.1309994},
    keywords = {Bragg frequency; Bragg scatterers; Doppler centroid measurements; Doppler resolution; MB estimators; along-track interferometry; multibaseline ATI-SAR; ocean surface currents; robust data inversion; robust ocean surface velocity estimation; scatterer propagation velocity; synthetic aperture radar; wind direction; Doppler radar; Doppler shift; oceanographic techniques; radiowave interferometry; remote sensing by radar; synthetic aperture radar;},
    
    }
    


  12. G. Luzi, M. Pieraccini, D. Mecatti, L. Noferini, G. Guidi, F. Moia, and C. Atzeni. Ground-based radar interferometry for landslides monitoring: atmospheric and instrumental decorrelation sources on experimental data. IEEE Trans. Geosci. Remote Sens., 42(11):2454-2466, November 2004. Keyword(s): Decorrelation, Temporal Decorrelation, Adaptive optics, Decorrelation, Image analysis, Instruments, Monitoring, Optical distortion, Optical interferometry, Radar interferometry, Synthetic aperture radar, Terrain factors, data acquisition, decorrelation, geomorphology, geophysical signal processing, radar imaging, radiowave interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), 5.725 GHz, AD 2002, C-band ground-based equipment, Civita di Bagnoregio, Italy, SAR image acquisition, ancient town, atmospheric decorrelation sources, coherent synthetic aperture radar, geometric distortion, ground-based radar interferometry, instrumental decorrelation sources, interferometric data, landslide monitoring, mechanical stability, optical photogrammetry, spatial decorrelation, temporal decorrelation, terrain movements, 65, Decorrelation, SAR, differential interferometry, ground-based synthetic aperture radar, phase stability, synthetic aperture radar;.
    Abstract: The application of ground-based radar interferometry for landslide monitoring is analyzed: a case study based on an experimental campaign carried out in Italy during 2002 is discussed. Interferometric data obtained from coherent synthetic aperture radar (SAR) images acquired by means of C-band ground-based equipment are analyzed. The campaign was aimed at retrieving potential terrain movements of a small landslide observed hundreds of meters away. Critical aspects related to spatial and temporal decorrelation are discussed: the use of optical photogrammetry as a technique for evaluating mechanical stability and correcting geometric distortion is presented. Results also confirmed that the application of ground-based radar interferometry can be attractive and effective if the acquired SAR images maintain an adequate coherence on different dates.

    @Article{luziPieracciniMecattiNoferiniGuidiMoiaAtzeniTGRS2004GroundBasedSAR,
    author = {Luzi, G. and Pieraccini, M. and Mecatti, D. and Noferini, L. and Guidi, G. and Moia, F. and Atzeni, C.},
    title = {Ground-based radar interferometry for landslides monitoring: atmospheric and instrumental decorrelation sources on experimental data},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2004},
    volume = {42},
    number = {11},
    pages = {2454-2466},
    month = nov,
    issn = {0196-2892},
    abstract = {The application of ground-based radar interferometry for landslide monitoring is analyzed: a case study based on an experimental campaign carried out in Italy during 2002 is discussed. Interferometric data obtained from coherent synthetic aperture radar (SAR) images acquired by means of C-band ground-based equipment are analyzed. The campaign was aimed at retrieving potential terrain movements of a small landslide observed hundreds of meters away. Critical aspects related to spatial and temporal decorrelation are discussed: the use of optical photogrammetry as a technique for evaluating mechanical stability and correcting geometric distortion is presented. Results also confirmed that the application of ground-based radar interferometry can be attractive and effective if the acquired SAR images maintain an adequate coherence on different dates.},
    doi = {10.1109/TGRS.2004.836792},
    file = {:luziPieracciniMecattiNoferiniGuidiMoiaAtzeniTGRS2004GroundBasedSAR.pdf:PDF},
    keywords = {Decorrelation, Temporal Decorrelation, Adaptive optics;Decorrelation;Image analysis;Instruments;Monitoring;Optical distortion;Optical interferometry;Radar interferometry;Synthetic aperture radar;Terrain factors; data acquisition; decorrelation; geomorphology; geophysical signal processing; radar imaging; radiowave interferometry; remote sensing by radar; synthetic aperture radar; terrain mapping; topography (Earth); 5.725 GHz; AD 2002; C-band ground-based equipment; Civita di Bagnoregio; Italy; SAR image acquisition; ancient town; atmospheric decorrelation sources; coherent synthetic aperture radar; geometric distortion; ground-based radar interferometry; instrumental decorrelation sources; interferometric data; landslide monitoring; mechanical stability; optical photogrammetry; spatial decorrelation; temporal decorrelation; terrain movements;65;Decorrelation;SAR;differential interferometry;ground-based synthetic aperture radar;phase stability;synthetic aperture radar;},
    pdf = {../../../docs/luziPieracciniMecattiNoferiniGuidiMoiaAtzeniTGRS2004GroundBasedSAR.pdf},
    
    }
    


  13. Andrew S. Milman. The Hyperbolic Geometry of SAR Imaging. Submitted to RADIO SCIENCE, 0(0):0-0, 2004. Keyword(s): SAR Processing, Hyperbolic Functions, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Stolt Mapping.
    Abstract: This paper shows how we can use hyperbolic functions to write an exact mathematical representation of SAR imaging. This problem is primarily a geometric one, that of accounting for curved wavefronts: the spirit of this paper is to emphasize these geometrical properties over electromagnetic ones. This gives us a new and fruitful way to think about SAR imaging. Within this framework, I show how to correct for deviations of a radar from a straight flight path. This method will work even in situations where the curvature of the wavefronts is very large, where traditional methods do not. The image-formation algorithm, called omega-k migration, that results from this analysis of SAR imaging is simpler and faster than polar formatting, especially for radars with very large beamwidths as they will at very low frequencies. As an added benefit, omega-k migration is surprisingly simple to derive.

    @Article{milmanSubmitted:Hyperbolic,
    Title = {{The Hyperbolic Geometry of SAR Imaging}},
    Author = {Andrew S. Milman},
    Number = {0},
    Pages = {0-0},
    Url = {http://home.cfl.rr.com/pt/hyperbolic.pdf},
    Volume = {0},
    Year = {2004},
    Abstract = {This paper shows how we can use hyperbolic functions to write an exact mathematical representation of SAR imaging. This problem is primarily a geometric one, that of accounting for curved wavefronts: the spirit of this paper is to emphasize these geometrical properties over electromagnetic ones. This gives us a new and fruitful way to think about SAR imaging. Within this framework, I show how to correct for deviations of a radar from a straight flight path. This method will work even in situations where the curvature of the wavefronts is very large, where traditional methods do not. The image-formation algorithm, called omega-k migration, that results from this analysis of SAR imaging is simpler and faster than polar formatting, especially for radars with very large beamwidths as they will at very low frequencies. As an added benefit, omega-k migration is surprisingly simple to derive.},
    Journal = {Submitted to RADIO SCIENCE},
    Keywords = {SAR Processing, Hyperbolic Functions, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Wavenumber Domain Algorithm, omega-k, Range Migration Algorithm, Stolt Mapping},
    Pdf = {../../../docs/milmanSubmitted.pdf} 
    }
    


  14. G. Nico, D. Leva, G. Antonello, and D. Tarchi. Ground-based SAR interferometry for terrain mapping: theory and sensitivity analysis. IEEE_J_GRS, 42(6):1344-1350, June 2004. Keyword(s): radar theory, radiowave interferometry, remote sensing by radar, sensitivity analysis, synthetic aperture radar, terrain mapping, GB-SAR interferometry, GB-SAR system, InSAR, digital elevation model, ground-based SAR interferometry, ground-based radar, phase-to-height relationship, sensitivity analysis, synthetic aperture radar, terrain mapping, Analytical models, Aperture antennas, Focusing, Radar antennas, Radar imaging, Rails, Sensitivity analysis, Synthetic aperture radar, Synthetic aperture radar interferometry, Terrain mapping, DEM, Digital elevation model, GB, InSAR, SAR, ground-based, radar, synthetic aperture radar, synthetic aperture radar interferometry.
    @Article{Nico2004,
    author = {G. Nico and D. Leva and G. Antonello and D. Tarchi},
    title = {Ground-based {SAR} interferometry for terrain mapping: theory and sensitivity analysis},
    journal = IEEE_J_GRS,
    year = {2004},
    volume = {42},
    number = {6},
    month = jun,
    pages = {1344--1350},
    issn = {0196-2892},
    doi = {10.1109/TGRS.2004.826556},
    keywords = {radar theory, radiowave interferometry, remote sensing by radar, sensitivity analysis, synthetic aperture radar, terrain mapping, GB-SAR interferometry, GB-SAR system, InSAR, digital elevation model, ground-based SAR interferometry, ground-based radar, phase-to-height relationship, sensitivity analysis, synthetic aperture radar, terrain mapping, Analytical models, Aperture antennas, Focusing, Radar antennas, Radar imaging, Rails, Sensitivity analysis, Synthetic aperture radar, Synthetic aperture radar interferometry, Terrain mapping, DEM, Digital elevation model, GB, InSAR, SAR, ground-based, radar, synthetic aperture radar, synthetic aperture radar interferometry},
    owner = {ofrey},
    
    }
    


  15. Mats I. Pettersson. Detection of Moving Targets in Wideband SAR. IEEE Transactions on Aerospace and Electronic Systems, 40(3):780-796, July 2004. Keyword(s): SAR Processing, Fast Back-Projection, Factorized Back-Projection, Time-Domain Back-Projection, TDBP, Back-Projection, Moving Target Indication, Ultra-Wideband SAR, Wideband SAR, VHF SAR, UHF SAR, CARABAS, LORA, Airborne SAR, C-Band.
    Abstract: A likelihood ratio is proposed for moving target detection in a wideband (WB) synthetic aperture radar (SAR) system. WB is defined here as any systems having a large fractional bandwidth, i.e., an ultra wide frequency band combined with a wide antenna beam. The developed method combines time-domain fast backprojection SAR processing methods with moving target detection using space-time processing. The proposed method reduces computational load when sets of relative speeds can be tested using the same clutter-suppressed subaperture beams. The proposed method is tested on narrowband radar data.

    @Article{Pettersson04:BackprojMTI,
    Title = {{Detection of Moving Targets in Wideband SAR}},
    Author = {Mats I. Pettersson},
    Month = jul,
    Number = {3},
    Pages = {780-796},
    Url = {http://ieeexplore.ieee.org/iel5/7/29502/01337454.pdf},
    Volume = {40},
    Year = {2004},
    Abstract = {A likelihood ratio is proposed for moving target detection in a wideband (WB) synthetic aperture radar (SAR) system. WB is defined here as any systems having a large fractional bandwidth, i.e., an ultra wide frequency band combined with a wide antenna beam. The developed method combines time-domain fast backprojection SAR processing methods with moving target detection using space-time processing. The proposed method reduces computational load when sets of relative speeds can be tested using the same clutter-suppressed subaperture beams. The proposed method is tested on narrowband radar data.},
    Comment = {Developed for wideband systems (CARABAS, LORA) but tested using airborne C-Band data (Andover system, center freq: 5.7 GHz, bandwidth: 82 Mhz, antenna beamwidth: 8 deg)},
    Journal = {IEEE Transactions on Aerospace and Electronic Systems},
    Keywords = {SAR Processing, Fast Back-Projection, Factorized Back-Projection, Time-Domain Back-Projection, TDBP, Back-Projection, Moving Target Indication, Ultra-Wideband SAR, Wideband SAR, VHF SAR,UHF SAR, CARABAS, LORA, Airborne SAR, C-Band},
    Pdf = {../../../docs/Pettersson04.pdf} 
    }
    


  16. Pau Prats, Andreas Reigber, and Jordi J. Mallorqui. Interpolation-free coregistration and phase-correction of airborne SAR interferograms. IEEE Geosci. Remote Sens. Lett., 1(3):188-191, 2004. Keyword(s): SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, synthetic aperture radar, airborne L-band repeat-pass interferometry, airborne SAR interferograms, azimuth registration errors, interpolation-free coregistration, navigation system, phase azimuth undulations, residual motion error correction, spectral diversity technique, synthetic aperture radar, Calibration, SAR, image registration, interferometry, Motion Compensation, repeat-pass interferometry, synthetic aperture radar.
    Abstract: This letter discusses the detection and correction of residual motion errors that appear in airborne synthetic aperture radar (SAR) interferograms due to the lack of precision in the navigation system. As it is shown, the effect of this lack of precision is twofold: azimuth registration errors and phase azimuth undulations. Up to now, the correction of the former was carried out by estimating the registration error and interpolating, while the latter was based on the estimation of the phase azimuth undulations to compensate the phase of the computed interferogram. In this letter, a new correction method is proposed, which avoids the interpolation step and corrects at the same time the azimuth phase undulations. Additionally, the spectral diversity technique, used to estimate registration errors, is critically analyzed. Airborne L-band repeat-pass interferometric data of the German Aerospace Center (DLR) experimental airborne SAR is used to validate the method.

    @Article{pratsReigberMallorqui04InterpolFreeCoregistration,
    author = {Prats, Pau and Reigber, Andreas and Mallorqui, Jordi J.},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    title = {{Interpolation-free coregistration and phase-correction of airborne SAR interferograms}},
    year = {2004},
    number = {3},
    pages = {188--191},
    volume = {1},
    abstract = {This letter discusses the detection and correction of residual motion errors that appear in airborne synthetic aperture radar (SAR) interferograms due to the lack of precision in the navigation system. As it is shown, the effect of this lack of precision is twofold: azimuth registration errors and phase azimuth undulations. Up to now, the correction of the former was carried out by estimating the registration error and interpolating, while the latter was based on the estimation of the phase azimuth undulations to compensate the phase of the computed interferogram. In this letter, a new correction method is proposed, which avoids the interpolation step and corrects at the same time the azimuth phase undulations. Additionally, the spectral diversity technique, used to estimate registration errors, is critically analyzed. Airborne L-band repeat-pass interferometric data of the German Aerospace Center (DLR) experimental airborne SAR is used to validate the method.},
    keywords = {SAR Processing, Airborne SAR, calibration, Interferometry, L-Band, synthetic aperture radar, airborne L-band repeat-pass interferometry, airborne SAR interferograms, azimuth registration errors, interpolation-free coregistration, navigation system, phase azimuth undulations, residual motion error correction, spectral diversity technique, synthetic aperture radar, Calibration, SAR, image registration, interferometry, Motion Compensation, repeat-pass interferometry, synthetic aperture radar},
    owner = {ofrey},
    pdf = {../../../docs/pratsReigberMallorqui04.pdf},
    url = {http://ieeexplore.ieee.org/iel5/8859/29155/01315629.pdf},
    
    }
    


  17. B.D. Rigling and R.L. Moses. Flight path strategies for 3-D scene reconstruction from bistatic SAR. Radar, Sonar and Navigation, IEE Proceedings -, 151(3):149-157, 2004. Keyword(s): SAR Processing, Non-linear Flight Path, SAR Tomography, Curvilinear SAR, Bistatic SAR, airborne radar, image reconstruction, parameter estimation, radar imaging, synthetic aperture radar, 3-D scene reconstruction, bistatic SAR, data collection strategy, flight path strategies, nonlinear receiver trajectory, nonparametric scene reconstructions, phase history, receiver flight paths, three-dimensional information, three-dimensional scattering centre location parameter estimates, three-dimensional scene information.
    Abstract: Proper design of receiver flight paths allows three-dimensional information to be encoded in sensed bistatic SAR phase history data. The authors show how the flight path taken by the receiving platform determines the resolution of nonparametric scene reconstructions and determines the variance of three-dimensional scattering centre location parameter estimates. Based on these relationships, a bistatic SAR data collection strategy can be designed, involving a nonlinear receiver trajectory that allows preservation of three-dimensional scene information.

    @Article{riglingMoses2004:BistaticNonLinearSARTomo,
    Title = {Flight path strategies for 3-D scene reconstruction from bistatic SAR},
    Author = {Rigling, B.D. and Moses, R.L.},
    ISSN = {1350-2395},
    Number = {3},
    Pages = {149--157},
    Url = {http://ieeexplore.ieee.org/iel5/2198/29130/01312057.pdf},
    Volume = {151},
    Year = {2004},
    Abstract = {Proper design of receiver flight paths allows three-dimensional information to be encoded in sensed bistatic SAR phase history data. The authors show how the flight path taken by the receiving platform determines the resolution of nonparametric scene reconstructions and determines the variance of three-dimensional scattering centre location parameter estimates. Based on these relationships, a bistatic SAR data collection strategy can be designed, involving a nonlinear receiver trajectory that allows preservation of three-dimensional scene information.},
    Booktitle = {Radar, Sonar and Navigation, IEE Proceedings -},
    Journal = {Radar, Sonar and Navigation, IEE Proceedings -},
    Keywords = {SAR Processing, Non-linear Flight Path, SAR Tomography, Curvilinear SAR, Bistatic SAR, airborne radar, image reconstruction, parameter estimation, radar imaging, synthetic aperture radar, 3-D scene reconstruction, bistatic SAR, data collection strategy, flight path strategies, nonlinear receiver trajectory, nonparametric scene reconstructions, phase history, receiver flight paths, three-dimensional information, three-dimensional scattering centre location parameter estimates, three-dimensional scene information},
    Owner = {ofrey},
    Pdf = {../../../docs/riglingMoses2004.pdf} 
    }
    


  18. B.D. Rigling and R.L. Moses. Polar format algorithm for bistatic SAR. IEEE_J_AES, 40(4):1147-1159, October 2004. Keyword(s): SAR Processing, Bistatic SAR, Time-Domain Back-Projection, TDBP, back-projection, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, polar format algorithm, synthetic aperture radar, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar.
    Abstract: Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N2 log2N) performance. An O(N2 log2N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.

    @Article{RiglingMoses2004:BiStaticPolarFormat,
    Title = {Polar format algorithm for bistatic {SAR}},
    Author = {Rigling, B.D. and Moses, R.L.},
    Doi = {10.1109/TAES.2004.1386870},
    ISSN = {0018-9251},
    Month = oct,
    Number = {4},
    Pages = {1147-1159},
    Volume = {40},
    Year = {2004},
    Abstract = {Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N2 log2N) performance. An O(N2 log2N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.},
    Journal = IEEE_J_AES,
    Keywords = {SAR Processing,Bistatic SAR, Time-Domain Back-Projection, TDBP, back-projection; bistatic far-field assumption; matched filtering; monostatic SAR image formation; phase history data; polar format algorithm; synthetic aperture radar; backpropagation; computational complexity; matched filters; radar imaging; synthetic aperture radar} 
    }
    


  19. Brian D. Rigling and Randolph L. Moses. Polar format algorithm for bistatic SAR. Aerospace and Electronic Systems, IEEE Transactions on, 40(4):1147-1159, 2004. Keyword(s): SAR Processing, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar, Back-Projection, Time-Domain Back-Projection, Fast Back-Projection, Bistatic SAR, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, Polar Format Algorithm, synthetic aperture radar.
    Abstract: Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N/sup 2/ log/sub 2/N) performance. An O(N/sup 2/ log/sub 2/N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.

    @Article{riglingMoses04:PFABackproj,
    Title = {Polar format algorithm for bistatic SAR},
    Author = {Rigling, Brian D. and Moses, Randolph L.},
    Number = {4},
    Pages = {1147--1159},
    Url = {http://ieeexplore.ieee.org/iel5/7/30189/01386870.pdf},
    Volume = {40},
    Year = {2004},
    Abstract = {Matched filtering (MF) of phase history data is a mathematically ideal but computationally expensive approach to bistatic synthetic aperture radar (SAR) image formation. Fast backprojection algorithms (BPAs) for image formation have recently been shown to give improved O(N/sup 2/ log/sub 2/N) performance. An O(N/sup 2/ log/sub 2/N) bistatic polar format algorithm (PFA) based on a bistatic far-field assumption is derived. This algorithm is a generalization of the popular PFA for monostatic SAR image formation and is highly amenable to implementation with existing monostatic image formation processors. Limits on the size of an imaged scene, analogous to those in monostatic systems, are derived for the bistatic PFA.},
    Journal = {Aerospace and Electronic Systems, IEEE Transactions on},
    Keywords = {SAR Processing, backpropagation, computational complexity, matched filters, radar imaging, synthetic aperture radar, Back-Projection, Time-Domain Back-Projection, Fast Back-Projection, Bistatic SAR, bistatic far-field assumption, matched filtering, monostatic SAR image formation, phase history data, Polar Format Algorithm, synthetic aperture radar},
    Owner = {ofrey},
    Pdf = {../../../docs/riglingMoses04.pdf} 
    }
    


  20. Z. Su, Y. Peng, and X. Wang. Efficient algorithm for three-dimensional target feature extraction via CLSAR. Electronics Letters, 40(15):965-966, 2004. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR, fast Fourier transforms, feature extraction, radar imaging, synthetic aperture radar, Cramer-Rao bounds, LODIPS algorithm, RELAX algorithm, SNR, computational load, curvilinear synthetic aperture radar system, lower dimensional FFT, lower dimensional position searching, three dimensional target feature extraction.
    Abstract: A lower dimensional position searching (LODIPS) algorithm is proposed for three-dimensional (3-D) target feature extraction via the curvilinear synthetic aperture radar (CLSAR) system. Compared with another similarly structured algorithm RELAX, the LODIPS algorithm dramatically reduces the computational load through the utilisation of lower dimensional FFTs. Simulation results show that the new algorithm can reach CRB at low SNR.

    @Article{suPengWang2004:NonLinearSARTomo,
    Title = {Efficient algorithm for three-dimensional target feature extraction via CLSAR},
    Author = {Su, Z. and Peng, Y. and Wang, X.},
    ISSN = {0013-5194},
    Number = {15},
    Pages = {965--966},
    Url = {http://ieeexplore.ieee.org/iel5/2220/29231/01318899.pdf},
    Volume = {40},
    Year = {2004},
    Abstract = {A lower dimensional position searching (LODIPS) algorithm is proposed for three-dimensional (3-D) target feature extraction via the curvilinear synthetic aperture radar (CLSAR) system. Compared with another similarly structured algorithm RELAX, the LODIPS algorithm dramatically reduces the computational load through the utilisation of lower dimensional FFTs. Simulation results show that the new algorithm can reach CRB at low SNR.},
    Booktitle = {Electronics Letters},
    Journal = {Electronics Letters},
    Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, Curvilinear SAR, fast Fourier transforms, feature extraction, radar imaging, synthetic aperture radar, Cramer-Rao bounds, LODIPS algorithm, RELAX algorithm, SNR, computational load, curvilinear synthetic aperture radar system, lower dimensional FFT, lower dimensional position searching, three dimensional target feature extraction},
    Owner = {ofrey},
    Pdf = {../../../docs/suPengWang2004.pdf} 
    }
    


  21. Robert N. Treuhaft, Beverly E. Law, and Gregory P. Asner. Forest Attributes from Radar Interferometric Structure and Its Fusion with Optical Remote Sensing. BioScience, 54(6):561-571, 2004. Keyword(s): SAR Processing, InSAR, SAR Interferometry, Forest, remote sensing, carbon cycle, LiDAR, optical remote sensing, forest ecology, SAR Tomography.
    Abstract: The possibility of global, three-dimensional remote sensing of forest structure with interferometric synthetic aperture radar (InSAR) bears on important forest ecological processes, particularly the carbon cycle. InSAR supplements two-dimensional remote sensing with information in the vertical dimension. Its strengths in potential for global coverage complement those of lidar (light detecting and ranging), which has the potential for high-accuracy vertical profiles over small areas. InSAR derives its sensitivity to forest vertical structure from the differences in signals received by two, spatially separate radar receivers. Estimation of parameters describing vertical structure requires multiple-polarization, multiple-frequency, or multiple-baseline InSAR. Combining InSAR with complementary remote sensing techniques, such as hyperspectral optical imaging and lidar, can enhance vertical-structure estimates and consequent biophysical quantities of importance to ecologists, such as biomass. Future InSAR experiments will supplement recent airborne and spaceborne demonstrations, and together with inputs from ecologists regarding structure, they will suggest designs for future spaceborne strategies for measuring global vegetation structure.

    @Article{treuhaftLawAsner2004:ForestAttributeFromInSAR,
    Title = {Forest Attributes from Radar Interferometric Structure and Its Fusion with Optical Remote Sensing},
    Author = {Robert N. Treuhaft and Beverly E. Law and Gregory P. Asner},
    Number = {6},
    Pages = {561--571},
    Volume = {54},
    Year = {2004},
    Abstract = {The possibility of global, three-dimensional remote sensing of forest structure with interferometric synthetic aperture radar (InSAR) bears on important forest ecological processes, particularly the carbon cycle. InSAR supplements two-dimensional remote sensing with information in the vertical dimension. Its strengths in potential for global coverage complement those of lidar (light detecting and ranging), which has the potential for high-accuracy vertical profiles over small areas. InSAR derives its sensitivity to forest vertical structure from the differences in signals received by two, spatially separate radar receivers. Estimation of parameters describing vertical structure requires multiple-polarization, multiple-frequency, or multiple-baseline InSAR. Combining InSAR with complementary remote sensing techniques, such as hyperspectral optical imaging and lidar, can enhance vertical-structure estimates and consequent biophysical quantities of importance to ecologists, such as biomass. Future InSAR experiments will supplement recent airborne and spaceborne demonstrations, and together with inputs from ecologists regarding structure, they will suggest designs for future spaceborne strategies for measuring global vegetation structure.},
    Journal = {BioScience},
    Keywords = {SAR Processing, InSAR, SAR Interferometry, Forest, remote sensing, carbon cycle, LiDAR, optical remote sensing, forest ecology, SAR Tomography},
    Owner = {ofrey},
    Pdf = {../../../docs/treuhaftLawAsner2004.pdf} 
    }
    


Conference articles

  1. A. Aguasca, A. Broquetas, J. J. Mallorqui, and X. Fabregas. A solid state L to X-band flexible ground-based SAR system for continuous monitoring applications. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 2, pages 757-760, September 2004. Keyword(s): GB-SAR, ground-based SAR, terrestrial SAR, airborne radar, interferometry, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, 100 MHz, L-X band ground-based SAR system, Synthetic Aperture Radar, airborne/satellite SAR systems, continuous terrain change monitoring, differential interferometry, optional polarimetric capability, ruggedized structure, Bandwidth, Buildings, Chirp, Frequency synthesizers, Interferometry, Monitoring, Solid state circuits, Spaceborne radar, Synthetic aperture radar, Transmitters.
    @InProceedings{Aguasca2004,
    author = {A. Aguasca and A. Broquetas and J. J. Mallorqui and X. Fabregas},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    title = {A solid state {L} to {X}-band flexible ground-based {SAR} system for continuous monitoring applications},
    year = {2004},
    month = sep,
    pages = {757--760},
    volume = {2},
    doi = {10.1109/IGARSS.2004.1368512},
    keywords = {GB-SAR,ground-based SAR, terrestrial SAR,airborne radar, interferometry, radar polarimetry, remote sensing by radar, synthetic aperture radar, terrain mapping, 100 MHz, L-X band ground-based SAR system, Synthetic Aperture Radar, airborne/satellite SAR systems, continuous terrain change monitoring, differential interferometry, optional polarimetric capability, ruggedized structure, Bandwidth, Buildings, Chirp, Frequency synthesizers, Interferometry, Monitoring, Solid state circuits, Spaceborne radar, Synthetic aperture radar, Transmitters},
    owner = {ofrey},
    
    }
    


  2. Emmanouil Alivizatos, Athanasios Potsis, Andreas Reigber, Alberto Moreira, and Nikolaos K. Uzunoglou. SAR Processing with Motion Compensation using the Extended Wavenumber Algorithm. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, pages 157-160, 2004. Keyword(s): SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR.
    Abstract: Modern Synthetic Aperture Radar (SAR) systems are continuously developing into the direction of higher spatial resolution and new modes of operation. This requires the use of high bandwidths, combined with wide azimuthal integration intervals. For focusing such data, a high quality SAR processing method is necessary, which is able to deal with more general sensor parameters. Wavenumber domain (Omega-K) processing is commonly accepted to be an ideal solution of the SAR focusing problem [1]. However, it is mostly applicable on spaceborne SAR data where a straight sensor trajectory is given. In case of airborne SAR data, wavenumber domain processing has certain limitations in performing high-precision motion compensation. In this paper, a detailed description of the motion errors in the wavenumber domain, as well as a motion compensation technique in this domain is formulated. The correction of the motion errors in the two dimensional spectral domain can result in very accurate second order motion compensation. This procedure can also be combined with a 2D sub-aperture technique, which results in a fully azimuth-frequency adaptive block processing scheme. The reason why the wavenumber MoCo can be very critical especially in low frequency-widebeam and high squinted SAR data, is that in these cases wavelength dependent corrections become mandatory.

    @InProceedings{AlivizatosReigberMoreiraUzunoglu04:ExtendedOmegaK,
    Title = {SAR Processing with Motion Compensation using the Extended Wavenumber Algorithm},
    Author = {Emmanouil Alivizatos and Athanasios Potsis and Andreas Reigber and Alberto Moreira and Nikolaos K. Uzunoglou},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Pages = {157-160},
    Year = {2004},
    Abstract = {Modern Synthetic Aperture Radar (SAR) systems are continuously developing into the direction of higher spatial resolution and new modes of operation. This requires the use of high bandwidths, combined with wide azimuthal integration intervals. For focusing such data, a high quality SAR processing method is necessary, which is able to deal with more general sensor parameters. Wavenumber domain (Omega-K) processing is commonly accepted to be an ideal solution of the SAR focusing problem [1]. However, it is mostly applicable on spaceborne SAR data where a straight sensor trajectory is given. In case of airborne SAR data, wavenumber domain processing has certain limitations in performing high-precision motion compensation. In this paper, a detailed description of the motion errors in the wavenumber domain, as well as a motion compensation technique in this domain is formulated. The correction of the motion errors in the two dimensional spectral domain can result in very accurate second order motion compensation. This procedure can also be combined with a 2D sub-aperture technique, which results in a fully azimuth-frequency adaptive block processing scheme. The reason why the wavenumber MoCo can be very critical especially in low frequency-widebeam and high squinted SAR data, is that in these cases wavelength dependent corrections become mandatory.},
    Keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/AlivizatosReigberMoreiraUzunoglu04.pdf} 
    }
    


  3. Elke Boerner, Hauke Fiedler, Gerhard Krieger, and Josef Mittermayer. A new Method for Total Zero Doppler Steering. In IGARSS '04, International Geoscience and Remote Sensing Symposium, September 2004. Keyword(s): SAR Processing, Steering, Yaw Steering, Attitude Steering, Doppler Centroid, Zero Doppler Steering, Total Zero Doppler Steering.
    Abstract: This paper describes a new method to perform zero Doppler steering, namely Total Zero Doppler Steering. It is developed for spaceborne synthetic aperture radar (SAR) systems. This new method combines the yaw-steering with an additional pitch-steering, resulting in a Doppler centroid of theoretically zero Hertz over the whole desired range of incidence angles for the whole orbit and simultaneously for left and right looking geometry.

    @InProceedings{BoernerFiedlerKriegerMittermayer04:Doppler,
    Title = {{A new Method for Total Zero Doppler Steering}},
    Author = {Elke Boerner and Hauke Fiedler and Gerhard Krieger and Josef Mittermayer},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Month = sep,
    Year = {2004},
    Abstract = {This paper describes a new method to perform zero Doppler steering, namely Total Zero Doppler Steering. It is developed for spaceborne synthetic aperture radar (SAR) systems. This new method combines the yaw-steering with an additional pitch-steering, resulting in a Doppler centroid of theoretically zero Hertz over the whole desired range of incidence angles for the whole orbit and simultaneously for left and right looking geometry.},
    Keywords = {SAR Processing, Steering, Yaw Steering, Attitude Steering, Doppler Centroid, Zero Doppler Steering, Total Zero Doppler Steering},
    Pdf = {../../../docs/BoernerFiedlerKriegerMittermayer04.pdf} 
    }
    


  4. F. Bordoni, A. Jakobsson, F. Lombardini, and F. Gini. Layover solution in multibaseline InSAR using interpolated arrays. In Proceedings of the Fourth IEEE International Symposium on Signal Processing and Information Technology, 2004, pages 175-178, 2004. Keyword(s): SAR Processing, Interferometry, SAR Tomography, Tomography, Layover, Array Interpolation, MUSIC, WSF.
    Abstract: This work deals with the problem of direction of direction of arrival estimation of interferometric synthetic aperture radar (InSAR) signals in presence of layover. The focus here is on realistic acquisition systems with a low number of phase centres and nonuniform array geometry. An interpolated array approach is proposed, in order to apply spectral estimation techniques designed for uniform linear arrays. In particular, interpolated MUSIC and weighted subspace fitting (WSF) algorithms are developed and investigated.

    @InProceedings{bordoniJakobssonLombardiniGini04:,
    Title = {Layover solution in multibaseline InSAR using interpolated arrays},
    Author = {Bordoni, F. and Jakobsson, A. and Lombardini, F. and Gini, F.},
    Booktitle = {Proceedings of the Fourth IEEE International Symposium on Signal Processing and Information Technology, 2004},
    Pages = {175--178},
    Url = {http://ieeexplore.ieee.org/iel5/9800/30910/01433715.pdf},
    Year = {2004},
    Abstract = {This work deals with the problem of direction of direction of arrival estimation of interferometric synthetic aperture radar (InSAR) signals in presence of layover. The focus here is on realistic acquisition systems with a low number of phase centres and nonuniform array geometry. An interpolated array approach is proposed, in order to apply spectral estimation techniques designed for uniform linear arrays. In particular, interpolated MUSIC and weighted subspace fitting (WSF) algorithms are developed and investigated.},
    Keywords = {SAR Processing, Interferometry, SAR Tomography, Tomography, Layover, Array Interpolation, MUSIC, WSF},
    Owner = {ofrey},
    Pdf = {../../../docs/bordoniJakobssonLombardiniGini04.pdf} 
    }
    


  5. Knut Eldhuset. Raw signal simulation for very high resolution SAR based on polarimetric scattering theory. In Proc. IEEE Int. Geosci. Remote Sens. Symp., September 2004. Keyword(s): SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Polarimetric Scattering Theory.
    Abstract: A method for raw signal simulation for extended SAR scenes with very high resolution is described. This simulator shall handle resolution better than 1 m, squinted geometry, elliptical orbit motion and use a polarimetric reflectivity matrix. Classical polarimetric scattering theory is based on electromagnetic harmonic fields using Maxwell s equations, Green's function, Huygens principle and Kirchhoff's approximation. Here, the scattering theory is modified for a chirp field. Calculated expressions for the scattered chirp field or the reflectivity matrix are presented. Such a reflectivity matrix can then be input to the inverse-EETF4 for raw data generation.

    @InProceedings{Eldhuset04:Simulation,
    Title = {Raw signal simulation for very high resolution {SAR} based on polarimetric scattering theory},
    Author = {Knut Eldhuset},
    Booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    Month = sep,
    Year = {2004},
    Abstract = {A method for raw signal simulation for extended SAR scenes with very high resolution is described. This simulator shall handle resolution better than 1 m, squinted geometry, elliptical orbit motion and use a polarimetric reflectivity matrix. Classical polarimetric scattering theory is based on electromagnetic harmonic fields using Maxwell s equations, Green's function, Huygens principle and Kirchhoff's approximation. Here, the scattering theory is modified for a chirp field. Calculated expressions for the scattered chirp field or the reflectivity matrix are presented. Such a reflectivity matrix can then be input to the inverse-EETF4 for raw data generation.},
    Keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Polarimetric Scattering Theory},
    Pdf = {../../../docs/Eldhuset04IGARSS.pdf} 
    }
    


  6. Joachim H. G. Ender, I. Walterscheid, and Andreas R. Brenner. New aspects of bistatic SAR: processing and experiments. In IGARSS '04, International Geoscience and Remote Sensing Symposium, September 2004. Keyword(s): SAR Processing, Bistatic SAR, Bistatic Processing, Back-Projection, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Airborne SAR.
    Abstract: The interest in bistatic synthetic aperture radar, using separated transmitter and receiver flying on different platforms, has been increasing rapidly over the last years. The reason for this are specific advantages, like the reduced vulnerability in military systems, forward looking SAR imaging, additional information about the target, or increased RCS (see e.g. [1]). Nevertheless, besides technical problems (see [2]) - like the synchronisation of the oscillators, the involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, double trajectory measurement and motion compensation - the processing of bistatic radar data is still not sufficiently solved. Some of the possibilities and problems will be discussed. The second part of this paper deals with a bistatic experiment performed in November 2003: Two SAR systems of FGAN have been flown on two different airplanes, the AER-II system has been used as a transmitter and the PAMIR system as a receiver. Different spatially invariant flight geometries have been tested. High resolution bistatic SAR images were generated successfully.

    @InProceedings{EnderWalterscheidBrenner04:bistaticSAR,
    Title = {{New aspects of bistatic SAR: processing and experiments}},
    Author = {Joachim H. G. Ender and I. Walterscheid and Andreas R. Brenner},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Month = sep,
    Year = {2004},
    Abstract = {The interest in bistatic synthetic aperture radar, using separated transmitter and receiver flying on different platforms, has been increasing rapidly over the last years. The reason for this are specific advantages, like the reduced vulnerability in military systems, forward looking SAR imaging, additional information about the target, or increased RCS (see e.g. [1]). Nevertheless, besides technical problems (see [2]) - like the synchronisation of the oscillators, the involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, double trajectory measurement and motion compensation - the processing of bistatic radar data is still not sufficiently solved. Some of the possibilities and problems will be discussed. The second part of this paper deals with a bistatic experiment performed in November 2003: Two SAR systems of FGAN have been flown on two different airplanes, the AER-II system has been used as a transmitter and the PAMIR system as a receiver. Different spatially invariant flight geometries have been tested. High resolution bistatic SAR images were generated successfully.},
    Keywords = {SAR Processing, Bistatic SAR, Bistatic Processing, Back-Projection, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Doppler Algorithm, Airborne SAR},
    Pdf = {../../../docs/EnderWalterscheidBrenner04.pdf} 
    }
    


  7. G. Fornaro, Giorgio Franceschetti, and S. Perna. Motion Compensation of Squinted Airborne SAR Raw Data: Role of Processing Geometry. In Proc. IEEE Int. Geosci. Remote Sens. Symp., September 2004. Keyword(s): SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR.
    Abstract: We discuss the role of processing geometry and the problem of motion compensation for non zero squint in airborne SAR processing.

    @InProceedings{franceschettiPernaFornaro04:Moco,
    author = {G. Fornaro and Giorgio Franceschetti and S. Perna},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    title = {Motion Compensation of Squinted Airborne {SAR} Raw Data: Role of Processing Geometry},
    year = {2004},
    month = sep,
    abstract = {We discuss the role of processing geometry and the problem of motion compensation for non zero squint in airborne SAR processing.},
    keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Extended omega-k, Extended Wavenumber Domain Algorithm, Motion Compensation, Squinted SAR, Airborne SAR},
    pdf = {../../../docs/franceschettiPernaFornaro04.pdf},
    
    }
    


  8. G. Fornaro and F. Serafino. Spaceborne 3D SAR Tomography: experiments with ERS data. In Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International, volume 2, pages 1240-1243, 2004. Keyword(s): SAR Processing, SAR Tomography, Tomography, data acquisition, image processing, radar cross-sections, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, tomography, 3D back-scattering property, ERS data, European Remote Sensing, multibaseline SAR experiment, spaceborne 3D SAR tomography.
    Abstract: This paper presents the first results of a multibaseline SAR experiments for the reconstruction of the 3D back-scattering properties of ground scenes by using ERS data.

    @InProceedings{fornaroSerafino04:Tomo,
    Title = {Spaceborne 3D SAR Tomography: experiments with ERS data},
    Author = {Fornaro, G. and Serafino, F.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International},
    Pages = {1240--1243},
    Url = {http://ieeexplore.ieee.org/iel5/9436/29945/01368640.pdf},
    Volume = {2},
    Year = {2004},
    Abstract = {This paper presents the first results of a multibaseline SAR experiments for the reconstruction of the 3D back-scattering properties of ground scenes by using ERS data.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, data acquisition, image processing, radar cross-sections, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, tomography, 3D back-scattering property, ERS data, European Remote Sensing, multibaseline SAR experiment, spaceborne 3D SAR tomography},
    Owner = {ofrey},
    Pdf = {../../../docs/fornaroSerafinoTomo04.pdf} 
    }
    


  9. Othmar Frey, Erich Meier, Daniel Nüesch, and Achim Roth. Geometric Error Budget Analysis for TerraSAR-X. In Proc. EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, Ulm, Germany, pages 513-516, May 2004. Keyword(s): SAR Processing, SAR Geocoding, Geocoding, Error Budget Analysis, TerraSAR-X, Atmospheric Correction, Atmospheric Path Delay, Ionosheric Path Delay, Antenna Gain Pattern Correction.
    Abstract: The impact of potential error sources on geocoded products has been investigated with respect to the high resolution capabilities of the TerraSAR-X sensor. Datum shift parameters, maps, digital terrain and surface models have been identified as external error sources. The accuracy of the geocoded products depends heavily on the quality and availability of this information, which underlies regional variations. Error sources closely related to the sensor are its position, sampling window start time and Doppler centroid frequency. Another error source is given by atmospheric refraction. Ionospheric and atmospheric path delays have a considerable impact. Appropriate modeling can mitigate this effect. Further, high requirements on radiometric accuracy ask for an improved antenna gain pattern correction, which depends on the actual elevation angle and the terrain height.

    @InProceedings{freyMeierNueeschRoth04:ErrorBudget,
    author = {Othmar Frey and Erich Meier and Daniel N{\"u}esch and Achim Roth},
    title = {{Geometric Error Budget Analysis for TerraSAR-X}},
    booktitle = {Proc. EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    year = {2004},
    pages = {513-516},
    address = {Ulm, Germany},
    month = may,
    abstract = {The impact of potential error sources on geocoded products has been investigated with respect to the high resolution capabilities of the TerraSAR-X sensor. Datum shift parameters, maps, digital terrain and surface models have been identified as external error sources. The accuracy of the geocoded products depends heavily on the quality and availability of this information, which underlies regional variations. Error sources closely related to the sensor are its position, sampling window start time and Doppler centroid frequency. Another error source is given by atmospheric refraction. Ionospheric and atmospheric path delays have a considerable impact. Appropriate modeling can mitigate this effect. Further, high requirements on radiometric accuracy ask for an improved antenna gain pattern correction, which depends on the actual elevation angle and the terrain height.},
    file = {:freyMeierNueeschRoth04.pdf:PDF},
    keywords = {SAR Processing,SAR Geocoding,Geocoding,Error Budget Analysis,TerraSAR-X,Atmospheric Correction,Atmospheric Path Delay,Ionosheric Path Delay,Antenna Gain Pattern Correction},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMeierNueeschRoth04.pdf},
    
    }
    


  10. F. Gini and F. Lombardini. Multibaseline post-processing for SAR interferometry. In Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004, pages 20-29, 2004. Keyword(s): SAR Processing, SAR Tomography, Tomography, radar detection, radar imaging, radiowave interferometry, synthetic aperture radar, 3D mapping, XTI-SAR, additive white Gaussian noise, cross-track InSAR system, multibaseline InSAR processing, multicomponent signal corruption estimation, multiplicative noise, radar reflectivity retrieval, semitransparent volume scattering layer, signal detection, synthetic aperture radar, tomography.
    Abstract: In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights and radar reflectivities of natural layover areas by means of a cross-track InSAR (XTI-SAR) system. It is formulated as the problem of detecting and estimating a multicomponent signal corrupted by multiplicative noise and by additive white Gaussian noise. The problem of estimating the number of signal components in the presence of speckle is also addressed. Finally, a brief mention is given to recent research trends on robust methods for non-perfectly calibrated arrays and on MB-SAR tomography, which is an extension of MB-InSAR for full 3D mapping of semitransparent volume scattering layers.

    @InProceedings{giniLombardini04:Tomo,
    Title = {Multibaseline post-processing for SAR interferometry},
    Author = {Gini, F. and Lombardini, F.},
    Booktitle = {Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004},
    Pages = {20--29},
    Url = {http://ieeexplore.ieee.org/iel5/10049/32242/01502903.pdf},
    Year = {2004},
    Abstract = {In this paper we provide a tutorial description of recent results of the research activity at the University of Pisa on multibaseline (MB) InSAR processing. The main focus is on the problem of retrieving both heights and radar reflectivities of natural layover areas by means of a cross-track InSAR (XTI-SAR) system. It is formulated as the problem of detecting and estimating a multicomponent signal corrupted by multiplicative noise and by additive white Gaussian noise. The problem of estimating the number of signal components in the presence of speckle is also addressed. Finally, a brief mention is given to recent research trends on robust methods for non-perfectly calibrated arrays and on MB-SAR tomography, which is an extension of MB-InSAR for full 3D mapping of semitransparent volume scattering layers.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, radar detection, radar imaging, radiowave interferometry, synthetic aperture radar, 3D mapping, XTI-SAR, additive white Gaussian noise, cross-track InSAR system, multibaseline InSAR processing, multicomponent signal corruption estimation, multiplicative noise, radar reflectivity retrieval, semitransparent volume scattering layer, signal detection, synthetic aperture radar, tomography},
    Owner = {ofrey},
    Pdf = {../../../docs/giniLombardiniTomo04.pdf} 
    }
    


  11. B. Hallberg, G. Smith, A. Olofsson, and Lars M. H. Ulander. Performance Simulation of Spaceborne P-band SAR for Global Biomass Retrieval. In IGARSS '04, International Geoscience and Remote Sensing Symposium, September 2004. Keyword(s): SAR Processing, Simulation, P-Band, Biomass Retrieval, Forest.
    Abstract: This paper evaluates the use of a spaceborne lowfrequency synthetic aperture radar (SAR) for forest biomass retrieval. Airborne radar data are used as input to a SAR simulator in which SAR system parameters of the assumed spaceborne system and propagation effects in the ionosphere (primarily scintillation and Faraday rotation) are modelled. The simulations are performed for different iononospheric perturbation states. Some simulated spaceborne low-frequency SAR images over boreal forest are shown and their usefulness for forest biomass retrieval are studied and discussed. The results indicate that it is possible to separate boreal forest into three classes assuming a moderate distorted ionosphere.

    @InProceedings{HallbergSmithOlofssonUlander04:Simulation,
    Title = {{Performance Simulation of Spaceborne P-band SAR for Global Biomass Retrieval}},
    Author = {B. Hallberg and G. Smith and A. Olofsson and Lars M. H. Ulander},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Month = sep,
    Year = {2004},
    Abstract = {This paper evaluates the use of a spaceborne lowfrequency synthetic aperture radar (SAR) for forest biomass retrieval. Airborne radar data are used as input to a SAR simulator in which SAR system parameters of the assumed spaceborne system and propagation effects in the ionosphere (primarily scintillation and Faraday rotation) are modelled. The simulations are performed for different iononospheric perturbation states. Some simulated spaceborne low-frequency SAR images over boreal forest are shown and their usefulness for forest biomass retrieval are studied and discussed. The results indicate that it is possible to separate boreal forest into three classes assuming a moderate distorted ionosphere.},
    Keywords = {SAR Processing, Simulation, P-Band, Biomass Retrieval, Forest},
    Pdf = {../../../docs/HallbergSmithOlofssonUlander04.pdf} 
    }
    


  12. Charles V. Jakowatz, Daniel E. Wahl, David A. Yocky, Brian K. Bray, Wallace J. Bow, and John A. Richards. Comparison of algorithms for use in real-time spotlight-mode SAR image formation. In Edmund G. Zelnio and Frederick D. Garber, editors, , volume 5427, pages 108-116, 2004. SPIE. Keyword(s): SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA, Range Migration Algorithm, RMA, omega-k, Comparison of Algorithms, Comparison of Focusing Algorithms, overlapped subaperture algorithm, OSA, Spotlight SAR, Spotlight-mode data.
    @Conference{jakowatzWahlYockyBrayBowRichardsSpotlightComparisonOfAlgorithms2004,
    author = {Charles V. Jakowatz and Daniel E. Wahl and David A. Yocky and Brian K. Bray and Wallace J. Bow, Jr. and John A. Richards},
    title = {Comparison of algorithms for use in real-time spotlight-mode {SAR} image formation},
    year = {2004},
    editor = {Edmund G. Zelnio and Frederick D. Garber},
    volume = {5427},
    number = {1},
    pages = {108-116},
    publisher = {SPIE},
    doi = {10.1117/12.548203},
    file = {:jakowatzWahlYockyBrayBowRichardsSpotlightComparisonOfAlgorithms2004.pdf:PDF},
    journal = {Algorithms for Synthetic Aperture Radar Imagery XI},
    keywords = {SAR Processing, Real-Time, Real-Time Processing, Real-Time SAR, Video SAR, Polar Format Algorithm, PFA, Range Migration Algorithm, RMA, omega-k, Comparison of Algorithms, Comparison of Focusing Algorithms, overlapped subaperture algorithm, OSA, Spotlight SAR, Spotlight-mode data},
    location = {Orlando, FL, USA},
    owner = {ofrey},
    pdf = {../../../docs/jakowatzWahlYockyBrayBowRichardsSpotlightComparisonOfAlgorithms2004.pdf},
    url = {http://link.aip.org/link/?PSI/5427/108/1},
    
    }
    


  13. Michael Jehle, Othmar Frey, David Small, Erich Meier, and Daniel Nüesch. Improved Knowledge of SAR Geometry through Atmospheric Modelling. In Proc. EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, Ulm, Germany, pages 909-911, May 2004. Keyword(s): Geocoding, Geometry, Atmospheric Path Delay, Ionosheric Path Delay, Tropospheric Path Delay, Atmospheric Modelling.
    Abstract: Satellites observing and measuring the Earth s surface with electromagnetic waves are subject to atmospheric path delays. These atmospheric effects on radar signal propagation modify the signal velocity and direction and can be considered by simple modeling. In order to increase the geolocation accuracy of spaceborne SAR applications we developed a software tool that accounts for atmospheric path delays. Well-calibrated spaceborne ENVISAT-ASAR data are used to investigate improvements to knowledge of the geometry of the scene.

    @InProceedings{jehleFreySmallMeierNueesch04:Atmosphere,
    author = {Michael Jehle and Othmar Frey and David Small and Erich Meier and Daniel N{\"u}esch},
    title = {Improved Knowledge of SAR Geometry through Atmospheric Modelling},
    booktitle = {Proc. EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    year = {2004},
    pages = {909-911},
    address = {Ulm, Germany},
    month = may,
    abstract = {Satellites observing and measuring the Earth s surface with electromagnetic waves are subject to atmospheric path delays. These atmospheric effects on radar signal propagation modify the signal velocity and direction and can be considered by simple modeling. In order to increase the geolocation accuracy of spaceborne SAR applications we developed a software tool that accounts for atmospheric path delays. Well-calibrated spaceborne ENVISAT-ASAR data are used to investigate improvements to knowledge of the geometry of the scene.},
    file = {:jehleFreySmallMeierNueesch04.pdf:PDF},
    keywords = {Geocoding, Geometry,Atmospheric Path Delay,Ionosheric Path Delay,Tropospheric Path Delay,Atmospheric Modelling},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/jehleFreySmallMeierNueesch04.pdf},
    
    }
    


  14. David Kettler, Doug Gray, and Nick Redding. The Point Spread Function for UWB SAR Imaging using Inversion of the Circular Radon Transform. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, Ulm, Germany, pages 175-178, May 2004. Keyword(s): SAR Processing, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Circular Radon Transform, CRT, Radon Transform, Ultra-Wideband SAR, Airborne SAR.
    Abstract: This paper summarises how SAR data collection can be viewed as taking the Circular Radon Transform of the ground reflectivity and outlines how image formation can be achieved by inverting the CRT via a Fourier-Hankel transform. An expression for the point spread function (PSF) of the imaging process is arrived at by means of an analytic inversion for a Gaussian. This PSF shows the effect on the image of the finite synthetic aperture. Illustrations of the PSF to show its range and aperture dependence are given.

    @InProceedings{kettlerGrayRedding04:Hankel,
    Title = {The Point Spread Function for UWB SAR Imaging using Inversion of the Circular Radon Transform},
    Author = {David Kettler and Doug Gray and Nick Redding},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Month = may,
    Pages = {175-178},
    Year = {2004},
    Abstract = {This paper summarises how SAR data collection can be viewed as taking the Circular Radon Transform of the ground reflectivity and outlines how image formation can be achieved by inverting the CRT via a Fourier-Hankel transform. An expression for the point spread function (PSF) of the imaging process is arrived at by means of an analytic inversion for a Gaussian. This PSF shows the effect on the image of the finite synthetic aperture. Illustrations of the PSF to show its range and aperture dependence are given.},
    Address = {Ulm, Germany},
    Keywords = {SAR Processing, Fourier-Hankel Inversion, Hankel Transform, Abel Transform, Circular Radon Transform, CRT, Radon Transform, Ultra-Wideband SAR, Airborne SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/kettlerGrayRedding04.pdf} 
    }
    


  15. Hiroshi Kimura, Toshiyuki Mizuno, Konstantinos P. Papathanassiou, and Irena Hajnsek. Improvement of polarimetric SAR calibration based on the Quegan algorithm. In Proc. IEEE Int. Geosci. Remote Sens. Symp., volume 1, pages 187, September 2004. Keyword(s): SAR Processing, Polarimetry, Polarimetric Calibration, airborne radar, crosstalk, geophysical signal processing, radar polarimetry, synthetic aperture radar, CR response analysis, JAXA/NICT airborne Pi-SAR, L-band polarimetric SAR data, Quegan algorithm, cross-polarized channel, like/cross-polarized observed echo, natural/artificial target, noise imbalance, polarimetric SAR calibration, polarimetric classification, polarimetric cross-talk calibration algorithm, Calibration, Chromium, Crosstalk, L-band, Parameter estimation, Radar polarimetry, Radar scattering, Spaceborne radar, Stability analysis, Synthetic aperture radar.
    Abstract: The polarimetric cross-talk calibration algorithm proposed by Quegan, which is more general than the one proposed by van Zyl, is modified to improve polarimetric SAR calibration. L-band polarimetric SAR data acquired by the JAXA/NICT airborne Pi-SAR, including a variety of natural and artificial targets, are calibrated introducing noise imbalance of cross-polarized channels into the Quegan algorithm and deriving the cross-talk parameters from areas with low correlation between like and cross-polarized observed echoes. The achieved enhancement in stability of cross-talk parameter estimation and removal over is demonstrated in terms of CR response analysis and polarimetric classification result

    @InProceedings{kimuraMizunoPapathanassiouHajnsekIGARSS2004PolCalibration,
    author = {Kimura, Hiroshi and Mizuno, Toshiyuki and Papathanassiou, Konstantinos P. and Hajnsek, Irena},
    title = {Improvement of polarimetric SAR calibration based on the Quegan algorithm},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2004},
    volume = {1},
    pages = {187},
    month = sep,
    abstract = {The polarimetric cross-talk calibration algorithm proposed by Quegan, which is more general than the one proposed by van Zyl, is modified to improve polarimetric SAR calibration. L-band polarimetric SAR data acquired by the JAXA/NICT airborne Pi-SAR, including a variety of natural and artificial targets, are calibrated introducing noise imbalance of cross-polarized channels into the Quegan algorithm and deriving the cross-talk parameters from areas with low correlation between like and cross-polarized observed echoes. The achieved enhancement in stability of cross-talk parameter estimation and removal over is demonstrated in terms of CR response analysis and polarimetric classification result},
    doi = {10.1109/IGARSS.2004.1368990},
    file = {:kimuraMizunoPapathanassiouHajnsekIGARSS2004PolCalibration.pdf:PDF},
    keywords = {SAR Processing, Polarimetry, Polarimetric Calibration; airborne radar;crosstalk;geophysical signal processing;radar polarimetry;synthetic aperture radar;CR response analysis;JAXA/NICT airborne Pi-SAR;L-band polarimetric SAR data;Quegan algorithm;cross-polarized channel;like/cross-polarized observed echo;natural/artificial target;noise imbalance;polarimetric SAR calibration;polarimetric classification;polarimetric cross-talk calibration algorithm;Calibration;Chromium;Crosstalk;L-band;Parameter estimation;Radar polarimetry;Radar scattering;Spaceborne radar;Stability analysis;Synthetic aperture radar},
    pdf = {../../../docs/kimuraMizunoPapathanassiouHajnsekIGARSS2004PolCalibration.pdf},
    
    }
    


  16. John C. Kirk, Don Woods, and Joe Salzman. Efficient Motion-Tolerant Fopen SAR Processing. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, volume 1, Ulm, Germany, pages 179-182, May 2004. Keyword(s): SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Motion Compensation, Thinned Range Migration Algorithm, Airborne SAR.
    Abstract: The Range Migration Algorithm (RMA) is an efficient approach to process strip map data with large range cell migration. However, it is sensitive to cross track motion of the radar. To provide for a degree of motion tolerance, an applicable approach is to retain only a portion of the full processed image around a central reference point (CRP) where motion compensation is applied. This results in throwing away that part of the image that is potentially defocused with the result that this discarded data area has to be reprocessed with additional CRPs. This results in a processing in-efficiency that can greatly drive up the processing requirements. An efficient algorithm is being developed which alleviates this wasted data processing in-efficiency problem. This new algorithm, called tyhe Thinned RMA, operates by filtering the data to just the area to be processed and then resampling the data at a much lower rate. The RMA then proceeds normally, but now operates on a much reduced cross track data size. This approach can also provide a much greater tolerance to cross track motion. To date the algorithm as been developed and tested on simulated data and recorded phase history data. Processing speed-ups of approximately 4 to 1 are being achieved compared to a full RMA algorithm that retains a small patch about the CRP. Ultimately the algorithm will progress to a two stage version that will provide the optimum in motion tolerance and processing efficiency.

    @InProceedings{KirkWoodsSalzman04:Processing,
    Title = {{Efficient Motion-Tolerant Fopen SAR Processing}},
    Author = {John C. Kirk and Don Woods and Joe Salzman},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Month = may,
    Pages = {179-182},
    Volume = {1},
    Year = {2004},
    Abstract = {The Range Migration Algorithm (RMA) is an efficient approach to process strip map data with large range cell migration. However, it is sensitive to cross track motion of the radar. To provide for a degree of motion tolerance, an applicable approach is to retain only a portion of the full processed image around a central reference point (CRP) where motion compensation is applied. This results in throwing away that part of the image that is potentially defocused with the result that this discarded data area has to be reprocessed with additional CRPs. This results in a processing in-efficiency that can greatly drive up the processing requirements. An efficient algorithm is being developed which alleviates this wasted data processing in-efficiency problem. This new algorithm, called tyhe Thinned RMA, operates by filtering the data to just the area to be processed and then resampling the data at a much lower rate. The RMA then proceeds normally, but now operates on a much reduced cross track data size. This approach can also provide a much greater tolerance to cross track motion. To date the algorithm as been developed and tested on simulated data and recorded phase history data. Processing speed-ups of approximately 4 to 1 are being achieved compared to a full RMA algorithm that retains a small patch about the CRP. Ultimately the algorithm will progress to a two stage version that will provide the optimum in motion tolerance and processing efficiency.},
    Address = {Ulm, Germany},
    Keywords = {SAR Processing, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Motion Compensation, Thinned Range Migration Algorithm, Airborne SAR},
    Pdf = {../../../docs/KirkWoodsSalzman04.pdf} 
    }
    


  17. Gerhard Krieger, Nicolas Gebert, and Alberto Moreira. SAR Signal Reconstruction from Non-Uniform Displaced Phase Centre Sampling. In IGARSS '04, International Geoscience and Remote Sensing Symposium, September 2004. Keyword(s): SAR Processing, Bistatic SAR, Bistatic Processing, Dual Receive Antenna.
    Abstract: The displaced phase centre (DPC) technique will enable a wide swath SAR with high azimuth resolution. In a classic DPC system, the PRF has to be chosen such that the SAR carrier moves just one half of its antenna length between subsequent radar pulses. Any deviation from this PRF will result in a nonuniform sampling of the synthetic aperture. This paper shows that an unambiguous reconstruction of the SAR signal is also possible in case of such a non-optimum PRF. For this, an innovative reconstruction algorithm is derived, which enables a recovery of the unambiguous Doppler spectrum also in case of a non-uniform sampling of the synthetic aperture. This algorithm will also have a great potential for multistatic satellite constellations as well as the dual receive antennas in Radarsat II and TerraSAR-X.

    @InProceedings{KriegerGebertMoreira04:DisplacedPhase,
    Title = {{SAR Signal Reconstruction from Non-Uniform Displaced Phase Centre Sampling}},
    Author = {Gerhard Krieger and Nicolas Gebert and Alberto Moreira},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Month = sep,
    Year = {2004},
    Abstract = {The displaced phase centre (DPC) technique will enable a wide swath SAR with high azimuth resolution. In a classic DPC system, the PRF has to be chosen such that the SAR carrier moves just one half of its antenna length between subsequent radar pulses. Any deviation from this PRF will result in a nonuniform sampling of the synthetic aperture. This paper shows that an unambiguous reconstruction of the SAR signal is also possible in case of such a non-optimum PRF. For this, an innovative reconstruction algorithm is derived, which enables a recovery of the unambiguous Doppler spectrum also in case of a non-uniform sampling of the synthetic aperture. This algorithm will also have a great potential for multistatic satellite constellations as well as the dual receive antennas in Radarsat II and TerraSAR-X.},
    Keywords = {SAR Processing, Bistatic SAR, Bistatic Processing, Dual Receive Antenna},
    Pdf = {../../../docs/KriegerGebertMoreira04.pdf} 
    }
    


  18. J. Li and P. Stoica. Versatile robust Capon beamforming: theory and applications. In Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004, pages 38-42, July 2004. Keyword(s): SAR Processing, SAR Tomography, Tomography, Capon, Robust Capon Beamforming, RCB, acoustic imaging, array signal processing, beam steering, channel bank filters, covariance matrices, ground penetrating radar, image resolution, interference (signal), landmine detection, radar imaging CBRCB, CPRCB, DCRCB, FLGPR imaging system, RCF, SCB, acoustic imaging, constant-beamwidth RCB, constant-powerwidth RCB, covariance fitting formulation, doubly constrained robust Capon beamformer, forward-looking ground penetrating radar, interference rejection, landmine detection, rank-deficient robust Capon filter-bank approach, resolution, spectral estimation, standard Capon beamformer, steering vector.
    Abstract: The standard Capon beamformer (SCB) has better resolution and much better interference rejection capability than the data-independent beamformer provided that the array steering vector corresponding to the signal-of-interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice), the performance of the Capon beamformer may become worse than that of the data-independent beamformer. Most of the early suggested robust adaptive methods are rather ad hoc in that the choice of their parameters are not directly related to the uncertainly of the steering vector. In this paper we provide a review of the recently proposed robust Capon beam-former (RCB) and doubly constrained robust Capon beamformer (DCRCB), which directly address the uncertainty of the steering vector and naturally extend the covariance fitting formulation of SCB to the case of uncertain steering vectors by enforcing a double constraint on the steering vector, viz. a constant norm constraint and an uncertainty set constraint. We also present several extensions and applications of RCB including constant-powerwidth RCB (CPRCB) and constant-beamwidth RCB (CBRCB) for acoustic imaging, rank-deficient robust Capon filter-bank (RCF) approach for spectral estimation, and rank-deficient RCB for landmine detection using forward-looking ground penetrating radar (FLGPR) imaging systems. The excellent performances of RCB, DCRCB, and the various extensions of RCB are demonstrated by simulated and experimental examples.

    @InProceedings{liStoica2004:RobustCapon,
    author = {Li, J. and Stoica, P.},
    booktitle = {Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2004},
    title = {Versatile robust Capon beamforming: theory and applications},
    year = {2004},
    month = {jul},
    pages = {38-42},
    abstract = {The standard Capon beamformer (SCB) has better resolution and much better interference rejection capability than the data-independent beamformer provided that the array steering vector corresponding to the signal-of-interest (SOI) is accurately known. However, whenever the knowledge of the SOI steering vector is imprecise (as is often the case in practice), the performance of the Capon beamformer may become worse than that of the data-independent beamformer. Most of the early suggested robust adaptive methods are rather ad hoc in that the choice of their parameters are not directly related to the uncertainly of the steering vector. In this paper we provide a review of the recently proposed robust Capon beam-former (RCB) and doubly constrained robust Capon beamformer (DCRCB), which directly address the uncertainty of the steering vector and naturally extend the covariance fitting formulation of SCB to the case of uncertain steering vectors by enforcing a double constraint on the steering vector, viz. a constant norm constraint and an uncertainty set constraint. We also present several extensions and applications of RCB including constant-powerwidth RCB (CPRCB) and constant-beamwidth RCB (CBRCB) for acoustic imaging, rank-deficient robust Capon filter-bank (RCF) approach for spectral estimation, and rank-deficient RCB for landmine detection using forward-looking ground penetrating radar (FLGPR) imaging systems. The excellent performances of RCB, DCRCB, and the various extensions of RCB are demonstrated by simulated and experimental examples.},
    doi = {10.1109/SAM.2004.1502905},
    keywords = {SAR Processing, SAR Tomography, Tomography, Capon, Robust Capon Beamforming, RCB, acoustic imaging, array signal processing, beam steering, channel bank filters, covariance matrices, ground penetrating radar, image resolution, interference (signal), landmine detection, radar imaging CBRCB, CPRCB, DCRCB, FLGPR imaging system, RCF, SCB, acoustic imaging, constant-beamwidth RCB, constant-powerwidth RCB, covariance fitting formulation, doubly constrained robust Capon beamformer, forward-looking ground penetrating radar, interference rejection, landmine detection, rank-deficient robust Capon filter-bank approach, resolution, spectral estimation, standard Capon beamformer, steering vector},
    owner = {ofrey},
    pdf = {../../../docs/liStoica2004.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1502905},
    
    }
    


  19. M. Limbach, B. Gabler, and Ralf Horn. Fine Resolution, fully Polarimetric P-band subsystem for E-SAR -- Technique and Results. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, pages 275-278, 2004. Keyword(s): SAR Processing, ESAR, P-Band, Airborne SAR, Polarimetry, Polarimetric P-Band.
    Abstract: The design of the P-band subsystem of DLR's E-SAR system is presented in this paper. With a new microstrip patch antenna and other key hardware components a bandwidth of more than 28% at a lower centre frequency is achieved. The system parameters correspond to a range resolution better than 2.1m. Measurements of system gain, cross polarisation suppression, system sensitivity and some antenna parameters are shown.

    @InProceedings{limbachGablerHorn04:ESARPBand,
    Title = {Fine Resolution, fully Polarimetric P-band subsystem for E-SAR -- Technique and Results},
    Author = {M. Limbach and B. Gabler and Ralf Horn},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Pages = {275-278},
    Year = {2004},
    Abstract = {The design of the P-band subsystem of DLR's E-SAR system is presented in this paper. With a new microstrip patch antenna and other key hardware components a bandwidth of more than 28% at a lower centre frequency is achieved. The system parameters correspond to a range resolution better than 2.1m. Measurements of system gain, cross polarisation suppression, system sensitivity and some antenna parameters are shown.},
    Keywords = {SAR Processing, ESAR, P-Band, Airborne SAR, Polarimetry,Polarimetric P-Band},
    Owner = {ofrey},
    Pdf = {../../../docs/limbachGablerHorn04.pdf} 
    }
    


  20. F. Lombardini, Joachim H. G. Ender, L. Rössing, M. Galletto, and L. Verrazzani. Experiments of interferometric layover solution with the three-antenna airborne AER-II SAR system. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS '04, volume 5, pages 3341-3344, September 2004. Keyword(s): SAR Processing, Capon, MUSIC, airborne radar, antenna arrays, radar imaging, radiowave interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, InSAR, SAR imagery, SAR Interferometry, advanced multibaseline operation, airborne experimental radar, calibration, dual-baseline single-pass SAR interferometer, electromagnetic tomography, higher-order interferometry, hybrid spatial spectral estimation, interferometric layover solution, layover-free interferometry, multichannel operation, nonparametric spectral estimation, parametric spectral estimation, spectral analysis, synthetic aperture radar, three-antenna airborne AER-II SAR System, three-antenna nonuniform array data.
    Abstract: Interest is recently growing in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional SAR and InSAR imagery. In this work we report about: experiments of the functionality of layover-free or higher-order interferometry with the dual-baseline single-pass SAR interferometer AER-II. Non-parametric, parametric and hybrid spatial spectral estimators are applied to process the three-antenna non uniform array data. Calibration issues, first real data results and impact of order selection are discussed for a bridge over the valley scene

    @InProceedings{lombardiniEnderRoessingGallettoVerrazzani2004:AERLayoverSolution,
    Title = {Experiments of interferometric layover solution with the three-antenna airborne {AER-II} {SAR} system},
    Author = {Lombardini, F. and Ender, Joachim H. G. and R{\"o}ssing, L. and Galletto, M. and Verrazzani, L.},
    Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS '04},
    Doi = {10.1109/IGARSS.2004.1370419},
    Month = sep,
    Pages = {3341--3344},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01370419},
    Volume = {5},
    Year = {2004},
    Abstract = {Interest is recently growing in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional SAR and InSAR imagery. In this work we report about: experiments of the functionality of layover-free or higher-order interferometry with the dual-baseline single-pass SAR interferometer AER-II. Non-parametric, parametric and hybrid spatial spectral estimators are applied to process the three-antenna non uniform array data. Calibration issues, first real data results and impact of order selection are discussed for a bridge over the valley scene},
    Keywords = {SAR Processing, Capon, MUSIC, airborne radar, antenna arrays, radar imaging, radiowave interferometry, remote sensing by radar, synthetic aperture radar, terrain mapping, InSAR, SAR imagery, SAR Interferometry, advanced multibaseline operation, airborne experimental radar, calibration, dual-baseline single-pass SAR interferometer, electromagnetic tomography, higher-order interferometry, hybrid spatial spectral estimation, interferometric layover solution, layover-free interferometry, multichannel operation, nonparametric spectral estimation, parametric spectral estimation, spectral analysis, synthetic aperture radar, three-antenna airborne AER-II SAR System, three-antenna nonuniform array data},
    Owner = {ofrey},
    Pdf = {../../../docs/lombardiniEnderRoessingGallettoVerrazzani2004.pdf} 
    }
    


  21. José Márquez-Martìnez and Josef Mittermayer. Analysis of Range Ambiguity Suppression methods in SAR by using a Novel Range Ambiguity Raw Data Simulator. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, volume 1, Ulm, Germany, pages 593-596, May 2004. Keyword(s): SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Range Ambiguity Suppression, ESAR, Airborne SAR.
    Abstract: This paper presents a novel range ambiguity raw data simulator (RAS). The simulator was used to investigate range ambiguity suppression obtained by means of up and down chirp coding for point targets and realistic scenes including extended targets. A pre-processing technique for up and down-chirp processing has also been developed. Different applications are investigated using data from the experimental SAR system from DLR (ESAR), either oriented to point target detection or to extended target analysis. Several image processing results with different range ambiguities ratios are presented.

    @InProceedings{MarquezMittermayer04:Simulator,
    Title = {{Analysis of Range Ambiguity Suppression methods in SAR by using a Novel Range Ambiguity Raw Data Simulator}},
    Author = {Jos{\'e} M{\'a}rquez-Mart{\'i}nez and Josef Mittermayer},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Month = may,
    Pages = {593-596},
    Volume = {1},
    Year = {2004},
    Abstract = {This paper presents a novel range ambiguity raw data simulator (RAS). The simulator was used to investigate range ambiguity suppression obtained by means of up and down chirp coding for point targets and realistic scenes including extended targets. A pre-processing technique for up and down-chirp processing has also been developed. Different applications are investigated using data from the experimental SAR system from DLR (ESAR), either oriented to point target detection or to extended target analysis. Several image processing results with different range ambiguities ratios are presented.},
    Address = {Ulm, Germany},
    Keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Range Ambiguity Suppression, ESAR, Airborne SAR},
    Pdf = {../../../docs/MarquezMittermayer04.pdf} 
    }
    


  22. Yibo Na, Hongbo Sun, Yee Hui Lee, Ling Chiat Tai, and Hian Lim Chan. Performance evaluation of back-projection and range migration algorithms in foliage penetration radar imaging. In Image Processing, 2004. ICIP '04. 2004 International Conference on, volume 1, pages 21-24, 2004. Keyword(s): SAR Processing, Back-Projection, omega-k, Comimage reconstruction, radar imaging, synthetic aperture radar, FOPEN SAR imaging, back-projection algorithm, computer-aided tomography, foliage penetration radar imaging, image reconstruction, range migration algorithm, seismic migration techniques, synthetic aperture radar.
    Abstract: In this paper, two relatively novel synthetic aperture radar (SAR) imaging techniques, namely the back-projection algorithm and range migration algorithm, are discussed. The back-projection algorithm originates from the medical imaging reconstruction technique called computer-aided tomography whereas the range migration algorithm is derived from seismic migration techniques. In this paper, both the back-projection and range migration algorithms are applied to foliage penetration (FOPEN) SAR imaging and performance comparisons are made. The simulations and experimental data processing results show that both algorithms are suitable for FOPEN radar imaging and that theoretical performances can be achieved.

    @InProceedings{naSunLeeTaiChan04:Backp,
    Title = {Performance evaluation of back-projection and range migration algorithms in foliage penetration radar imaging},
    Author = {Na, Yibo and Sun, Hongbo and Lee, Yee Hui and Tai, Ling Chiat and Chan, Hian Lim},
    Booktitle = {Image Processing, 2004. ICIP '04. 2004 International Conference on},
    Pages = {21--24},
    Url = {http://ieeexplore.ieee.org/iel5/9716/30672/01418679.pdf},
    Volume = {1},
    Year = {2004},
    Abstract = {In this paper, two relatively novel synthetic aperture radar (SAR) imaging techniques, namely the back-projection algorithm and range migration algorithm, are discussed. The back-projection algorithm originates from the medical imaging reconstruction technique called computer-aided tomography whereas the range migration algorithm is derived from seismic migration techniques. In this paper, both the back-projection and range migration algorithms are applied to foliage penetration (FOPEN) SAR imaging and performance comparisons are made. The simulations and experimental data processing results show that both algorithms are suitable for FOPEN radar imaging and that theoretical performances can be achieved.},
    ISSN = {1522-4880},
    Keywords = {SAR Processing, Back-Projection, omega-k, Comimage reconstruction, radar imaging, synthetic aperture radar, FOPEN SAR imaging, back-projection algorithm, computer-aided tomography, foliage penetration radar imaging, image reconstruction, range migration algorithm, seismic migration techniques, synthetic aperture radar},
    Owner = {ofrey},
    Pdf = {../../../docs/naSunLeeTaiChan04.pdf} 
    }
    


  23. Lam H. Nguyen, Marc Ressler, and Mehrdad Soumekh. Signal Processing and Image Formation Using Low-Frequency Ultra-Wideband Radar Data. In Russell S. Harmon, J. Thomas Broach, and John H. Holloway(Jr.), editors, Proceedings of SPIE: Detection and Remediation Technologies for Mines and Minelike Targets IX, volume SPIE 5415, pages 1053-1064, 2004. Keyword(s): SAR Processing, Ultra-Wideband SAR, Back-Projection, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Image Formation, RFI Suppression, Digital Spotlighting.
    Abstract: In support of the U.S. Army Night Vision And Electronic Sensors Directorate (NVESD), the U.S. Army Research Laboratory (ARL) has developed infrastructures, tools, and algorithms to evaluate the data set. This paper focuses on the signal processing and image formation using data from a low-frequency ultrawideband sensor. We examine various issues that are associated with this class of SAR databases such as radio frequency interference (RFI), the effects of spectral notches, and errors in motion measurement to image quality. We show the pre-processing steps such as frequency and phase calibration, radio frequency interference extraction. We also show the application of digital spotlight technique to correct motion errors introduced by the measurement system. Finally, we show the resulting SAR imagery of various minefields.

    @InProceedings{NguyenResslerSoumekh04:LowFreqUWB,
    Title = {{Signal Processing and Image Formation Using Low-Frequency Ultra-Wideband Radar Data}},
    Author = {Lam H. Nguyen and Marc Ressler and Mehrdad Soumekh},
    Booktitle = {Proceedings of SPIE: Detection and Remediation Technologies for Mines and Minelike Targets IX},
    Editor = {Russell S. Harmon and J. Thomas Broach and John H. Holloway(Jr.)},
    Pages = {1053-1064},
    Url = {http://spiedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PSISDG005415000001001053000001&idtype=cvips&gifs=yes},
    Volume = {SPIE 5415},
    Year = {2004},
    Abstract = {In support of the U.S. Army Night Vision And Electronic Sensors Directorate (NVESD), the U.S. Army Research Laboratory (ARL) has developed infrastructures, tools, and algorithms to evaluate the data set. This paper focuses on the signal processing and image formation using data from a low-frequency ultrawideband sensor. We examine various issues that are associated with this class of SAR databases such as radio frequency interference (RFI), the effects of spectral notches, and errors in motion measurement to image quality. We show the pre-processing steps such as frequency and phase calibration, radio frequency interference extraction. We also show the application of digital spotlight technique to correct motion errors introduced by the measurement system. Finally, we show the resulting SAR imagery of various minefields.},
    Keywords = {SAR Processing, Ultra-Wideband SAR, Back-Projection, Wavefront Reconstruction, Wavenumber Domain Algorithm, omega-k, Image Formation, RFI Suppression, Digital Spotlighting},
    Pdf = {../../../docs/NguyenResslerSoumekh04.pdf} 
    }
    


  24. Lam H. Nguyen, Marc Ressler, D. Wong, and Mehrdad Soumekh. Enhancement of backprojection SAR imagery using digital spotlighting preprocessing. In Radar Conference, 2004. Proceedings of the IEEE, pages 53-58, 2004. Keyword(s): SAR Processing, Back-Projection, Time-Domain Back-Projection, Digital Spotlighting, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression, Doppler effect, antialiasing, image enhancement, radar imaging, synthetic aperture radar, ARL boom-SAR data, Doppler aliasing suppression, PRF, SAR data filtering scheme, SAR imagery enhancement, azimuth-compressed SAR data, back-projection SAR imagery, digital spotlighting preprocessing, image fidelity improvement, radar radiation pattern, side lobe artifacts.
    Abstract: This paper examines signal processing methods for improving the fidelity of backprojection SAR imagery using a preprocessing method that suppresses Doppler aliasing as well as other side lobe artifacts that are introduced by the radar radiation pattern. The algorithm, known as digital spotlighting, imposes a filtering scheme on the azimuth-compressed SAR data, and manipulates the resultant spectral data to achieve a higher PRF to suppress the Doppler aliasing. The merits of the algorithm are studied using the ARL boom-SAR data.

    @InProceedings{nguyenResslerWongSoumekh04:Backproj,
    Title = {Enhancement of backprojection SAR imagery using digital spotlighting preprocessing},
    Author = {Nguyen, Lam H. and Ressler, Marc and Wong, D. and Mehrdad Soumekh},
    Booktitle = {Radar Conference, 2004. Proceedings of the IEEE},
    Pages = {53--58},
    Url = {http://ieeexplore.ieee.org/iel5/9199/29174/01316395.pdf},
    Year = {2004},
    Abstract = {This paper examines signal processing methods for improving the fidelity of backprojection SAR imagery using a preprocessing method that suppresses Doppler aliasing as well as other side lobe artifacts that are introduced by the radar radiation pattern. The algorithm, known as digital spotlighting, imposes a filtering scheme on the azimuth-compressed SAR data, and manipulates the resultant spectral data to achieve a higher PRF to suppress the Doppler aliasing. The merits of the algorithm are studied using the ARL boom-SAR data.},
    Keywords = {SAR Processing,Back-Projection,Time-Domain Back-Projection,Digital Spotlighting, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression, Doppler effect, antialiasing, image enhancement, radar imaging, synthetic aperture radar, ARL boom-SAR data, Doppler aliasing suppression, PRF, SAR data filtering scheme, SAR imagery enhancement, azimuth-compressed SAR data, back-projection SAR imagery, digital spotlighting preprocessing, image fidelity improvement, radar radiation pattern, side lobe artifacts},
    Owner = {ofrey},
    Pdf = {../../../docs/nguyenResslerWongSoumekh04.pdf} 
    }
    


  25. Lam H. Nguyen, Tuan Ton, David Wong, and Mehrdad Soumekh. Adaptive coherent suppression of multiple wide-bandwidth RFI sources in SAR. In Edmund G. Zelnio and Frederick D. Garber, editors, Algorithms for Synthetic Aperture Radar Imagery XI, volume 5427, pages 1-16, 2004. SPIE. Keyword(s): SAR Processing, RFI Suppression, Ultra-Wideband SAR, Wide-Bandwidth RFI, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression.
    Abstract: This paper is concerned with suppressing multiple wide-bandwidth radio frequency interference (RFI) sources in SAR systems. A coherent processing of passive radar (sniff) data is presented to diminish the effects of wide-bandwidth as well as narrow-bandwidth RFI sources in the active radar data that are collected by a SAR system. The approach is based on a two-dimensional adaptive filtering of the active SAR data using the passive sniff data as the reference signal. A similar mathematical (signal) model and processing is also utilized to suppress self-induced resonance (SIR) signals that are generated by the interaction of the radar-carrying platform and the transmitted radar signal. Results are shown using the Army Research Laboratory (ARL) low-frequency, ultra-wideband (UWB) imaging radar (Boom-SAR).

    @InProceedings{nguyenTonWongSoumekh04:RFI,
    Title = {Adaptive coherent suppression of multiple wide-bandwidth RFI sources in SAR},
    Author = {Lam H. Nguyen and Tuan Ton and David Wong and Mehrdad Soumekh},
    Booktitle = {Algorithms for Synthetic Aperture Radar Imagery XI},
    Editor = {Edmund G. Zelnio and Frederick D. Garber},
    Number = {1},
    Pages = {1-16},
    Publisher = {SPIE},
    Url = {http://link.aip.org/link/?PSI/5427/1/1},
    Volume = {5427},
    Year = {2004},
    Abstract = {This paper is concerned with suppressing multiple wide-bandwidth radio frequency interference (RFI) sources in SAR systems. A coherent processing of passive radar (sniff) data is presented to diminish the effects of wide-bandwidth as well as narrow-bandwidth RFI sources in the active radar data that are collected by a SAR system. The approach is based on a two-dimensional adaptive filtering of the active SAR data using the passive sniff data as the reference signal. A similar mathematical (signal) model and processing is also utilized to suppress self-induced resonance (SIR) signals that are generated by the interaction of the radar-carrying platform and the transmitted radar signal. Results are shown using the Army Research Laboratory (ARL) low-frequency, ultra-wideband (UWB) imaging radar (Boom-SAR).},
    Keywords = {SAR Processing, RFI Suppression, Ultra-Wideband SAR,Wide-Bandwidth RFI, Boom-SAR, Self-Induced Resonance Suppression, SIR Suppression, RFI Suppression},
    Owner = {ofrey},
    Pdf = {../../../docs/nguyenTonWongSoumekh04.pdf} 
    }
    


  26. David Small, Michael Jehle, Erich Meier, and Daniel Nüesch. Radiometric Terrain Correction Incorporating Local Antenna Gain. In Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar, Ulm, Germany, pages 929-932, May 2004. Keyword(s): SAR Geocoding, Radiometric Correction, Radiometric Terrain Correction, Radiometric Calibration, Calibration, Local Antenna Gain.
    Abstract: Radiometric terrain correction consists of normalising a SAR image for well-understood backscatter contributions in order to amplify less easily apparent influences (e.g. thematic land cover variance). A rigorous modelling of the SAR image formation process includes consideration of how foreshortening and layover create ambi guity when connecting map geometry grid points to and from counterparts in radar geometry (slant or ground range vs. azimuth). A radar amplitude image simulation is formed by iterating through a facetted DEM, calcu lating the accumulated illuminated area at every range and azimuth coordinate in radar geometry. We show how DEM-based image simulations gain further realism by incorporating knowledge of the SAR antenna's elevation an-tenna gain pattern (AGP). Although typical AGP corrections assume an ellipsoidal Earth, the AGP is actually draped upon the Earth's terrain. We quantify differences between estimates of local antenna gain and illuminated area performed using (a) the typical ellipsoid assumption, (b) a DEM. We demonstrate application of local antenna gain knowledge within the image simulation process using ENVISAT ASAR images acquired over Switzerland. We introduce a weighted resolution approach for robust combination of multiple radiometrically normalised terrain geocoded backscatter maps.

    @InProceedings{smallJehleMeierNueesch04:TerrainCorr,
    Title = {{Radiometric Terrain Correction Incorporating Local Antenna Gain}},
    Author = {David Small and Michael Jehle and Erich Meier and Daniel N{\"u}esch},
    Booktitle = {Proc. of EUSAR 2004 - 5th European Conference on Synthetic Aperture Radar},
    Month = may,
    Pages = {929-932},
    Year = {2004},
    Abstract = {Radiometric terrain correction consists of normalising a SAR image for well-understood backscatter contributions in order to amplify less easily apparent influences (e.g. thematic land cover variance). A rigorous modelling of the SAR image formation process includes consideration of how foreshortening and layover create ambi guity when connecting map geometry grid points to and from counterparts in radar geometry (slant or ground range vs. azimuth). A radar amplitude image simulation is formed by iterating through a facetted DEM, calcu lating the accumulated illuminated area at every range and azimuth coordinate in radar geometry. We show how DEM-based image simulations gain further realism by incorporating knowledge of the SAR antenna's elevation an-tenna gain pattern (AGP). Although typical AGP corrections assume an ellipsoidal Earth, the AGP is actually draped upon the Earth's terrain. We quantify differences between estimates of local antenna gain and illuminated area performed using (a) the typical ellipsoid assumption, (b) a DEM. We demonstrate application of local antenna gain knowledge within the image simulation process using ENVISAT ASAR images acquired over Switzerland. We introduce a weighted resolution approach for robust combination of multiple radiometrically normalised terrain geocoded backscatter maps.},
    Address = {Ulm, Germany},
    Keywords = {SAR Geocoding,Radiometric Correction, Radiometric Terrain Correction,Radiometric Calibration,Calibration,Local Antenna Gain},
    Owner = {ofrey},
    Pdf = {../../../docs/smallJehleMeierNueesch04.pdf} 
    }
    


  27. David Small, Michael Jehle, Erich Meier, and Daniel Nüesch. Radiometric terrain correction incorporating local antenna gain. In Proc. 5th EUSAR, Ulm, Germany, 2004. Keyword(s): SAR Processing, Radiometric Normalization.
    @InProceedings{smallJehleMeierNuesch2004:RadiometricNormalization,
    Title = {Radiometric terrain correction incorporating local antenna gain},
    Author = {David Small and Michael Jehle and Erich Meier and Daniel N\"uesch},
    Booktitle = {Proc. 5th EUSAR},
    Year = {2004},
    Address = {Ulm, Germany},
    Keywords = {SAR Processing, Radiometric Normalization},
    Owner = {ofrey} 
    }
    


  28. David Small, Erich Meier, and Daniel Nüesch. Robust radiometric terrain correction for SAR image comparisons. In IGARSS '04, International Geoscience and Remote Sensing Symposium, volume 3, pages 1730-1733, 2004. Keyword(s): backscatter, radiometry, remote sensing by radar, terrain mapping, AGP, ENVISAT ASAR images, Earth ellipsoid, Earth rolling terrain, SAR imagery, Switzerland, composite radar map, ideal flat terrain, local antenna gain pattern, mountainous terrain, normalized images, radar backscatter coefficient, radar brightness coefficient, radar equation, radiometric errors, radiometrically calibrated images, robust radar image simulation, robust radiometric terrain correction, robust technique, terrain geocoded images, terrain induced modulations, terrain variations.
    Abstract: We demonstrate a robust technique for radiometric terrain correction, whereby terrain-induced modulations of the radiometry of SAR imagery are modelled and corrected. The resulting normalized images may be more easily compared with other data sets acquired at different incidence angles, even opposing look directions. We begin by reviewing the radar equation, pointing out simplifications often made to reduce the complexity of calculating the backscatter coefficient, normalized either by ground area sigma0, or illuminated area projected into the look direction gamma0 . The integral over the illuminated area is often approximated by a scale factor modelling a simple planar slope, departing only slightly from ideal flat terrain: for gamma0, the radar brightness beta is normalized via modulation with the tangent of the local incidence angle. We quantify the radiometric errors introduced by ignoring terrain variations, comparing results based on (a) a robust radar image simulation-based approach properly modelling variations in local illuminated area, and (b) an ellipsoidal Earth assumption. A second simplification often made in solving for backscatter using the radar equation is the assumption that the local antenna gain does not vary significantly from a simple model draping the antenna gain pattern (AGP) across an Earth ellipsoid, returning the local antenna gain as a function of slant range alone. In reality, the AGP is draped across the Earth's rolling terrain retrieval of properly calibrated backscatter values should model these variations and compensate for them: although smaller than the errors caused by not property modelling variations in local illuminated area, they can be significant. We use well-calibrated and annotated ENVISAT ASAR images acquired over Switzerland to show how robust radiometric terrain correction, incorporating models for the variations of local illuminated area with terrain enables calibrated mixture of imagery acquired at differing incidence angles. Only robust retrieval of backscatter values enables such inter-mode comparisons - a capability that significantly reduces the required revisit time for monitoring changes to the radar backscatter. In conclusion, we describe a techn- ique for combining a set of terrain-geocoded and radiometrically calibrated images derived from ascending and descending passes and multiple incidence angles to create composite radar backscatter maps. At each point, the contribution of each image to the composite is weighted according to its local resolution. The resulting composite image manifests relatively uniform high ground resolution, even in highly mountainous terrain.

    @InProceedings{smallMeierNueesch04:TerrainCorr,
    Title = {Robust radiometric terrain correction for SAR image comparisons},
    Author = {Small, David and Meier, Erich and N{\"u}esch, Daniel},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Pages = {1730--1733},
    Url = {http://ieeexplore.ieee.org/iel5/9436/29946/01370666.pdf},
    Volume = {3},
    Year = {2004},
    Abstract = {We demonstrate a robust technique for radiometric terrain correction, whereby terrain-induced modulations of the radiometry of SAR imagery are modelled and corrected. The resulting normalized images may be more easily compared with other data sets acquired at different incidence angles, even opposing look directions. We begin by reviewing the radar equation, pointing out simplifications often made to reduce the complexity of calculating the backscatter coefficient, normalized either by ground area sigma0, or illuminated area projected into the look direction gamma0 . The integral over the illuminated area is often approximated by a scale factor modelling a simple planar slope, departing only slightly from ideal flat terrain: for gamma0, the radar brightness beta is normalized via modulation with the tangent of the local incidence angle. We quantify the radiometric errors introduced by ignoring terrain variations, comparing results based on (a) a robust radar image simulation-based approach properly modelling variations in local illuminated area, and (b) an ellipsoidal Earth assumption. A second simplification often made in solving for backscatter using the radar equation is the assumption that the local antenna gain does not vary significantly from a simple model draping the antenna gain pattern (AGP) across an Earth ellipsoid, returning the local antenna gain as a function of slant range alone. In reality, the AGP is draped across the Earth's rolling terrain retrieval of properly calibrated backscatter values should model these variations and compensate for them: although smaller than the errors caused by not property modelling variations in local illuminated area, they can be significant. We use well-calibrated and annotated ENVISAT ASAR images acquired over Switzerland to show how robust radiometric terrain correction, incorporating models for the variations of local illuminated area with terrain enables calibrated mixture of imagery acquired at differing incidence angles. Only robust retrieval of backscatter values enables such inter-mode comparisons - a capability that significantly reduces the required revisit time for monitoring changes to the radar backscatter. In conclusion, we describe a techn- ique for combining a set of terrain-geocoded and radiometrically calibrated images derived from ascending and descending passes and multiple incidence angles to create composite radar backscatter maps. At each point, the contribution of each image to the composite is weighted according to its local resolution. The resulting composite image manifests relatively uniform high ground resolution, even in highly mountainous terrain.},
    Journal = {Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International},
    Keywords = {backscatter, radiometry, remote sensing by radar, terrain mapping, AGP, ENVISAT ASAR images, Earth ellipsoid, Earth rolling terrain, SAR imagery, Switzerland, composite radar map, ideal flat terrain, local antenna gain pattern, mountainous terrain, normalized images, radar backscatter coefficient, radar brightness coefficient, radar equation, radiometric errors, radiometrically calibrated images, robust radar image simulation, robust radiometric terrain correction, robust technique, terrain geocoded images, terrain induced modulations, terrain variations},
    Owner = {ofrey},
    Pdf = {../../../docs/smallMeierNueesch04.pdf} 
    }
    


  29. David Small, Betlem Rosich, Erich Meier, and Daniel Nüesch. Geometric Calibration and Validation of ASAR Imagery. In CEOS SAR Workshop 2004, Ulm, May 2004. Keyword(s): SAR Geocoding, Calibration, Validation, Quality Assessment, ASAR, ENVISAT.
    Abstract: We describe work conducted to calibrate and then validate the geometry of ENVISAT ASAR products. A systematic error in range location was observed in ASAR products during the commissioning phase. A careful and complete analysis has been performed to establish the precise error. It has been compensated by updating the range gate bias (or sampling window start time bias). Validation of the absolute location accuracy of most ASAR products was performed subsequently. The location of surveyed targets is predicted using the satellite state vectors and ancillary timing information via the range and Doppler equations. The prediction's accuracy is affected by instrument bias, ionospheric and atmospheric path delay, as well as target survey errors. Transponders are in addition subject to internal delay uncertainty. The positions of the strong transponder and corner reflector targets in the images are measured to sub-sample accuracy by employing large oversampling factors. Initial and residual bias determinations were made using image acquisitions covering transponders and corner reflectors in the Netherlands, Canada, and Switzerland. Using a large number of independent targets helps reduce the influence of their independent survey errors. The highest resolution slant range single look complex (SLC) products (IMS, APS) were mainly used for testing. In addition, absolute location error was also measured on selected ground range products (IMP, APP, IMM, APM, WSM). Some ground range products also require treatment of multiple slant/ground range polynomials - proper handling is validated. For all test cases processed with precise orbits to date, the residual bias in the slant range direction has been smaller than the size of a single range sample. Predictability of target image location within ASAR image products is very high - better than experience with ERS-1/2, JERS-1, and RADARSAT-1. This result is encouraging, as it opens possibilities for ground control point (GCP) free terrain-geocoding and simplified interferometric processing.

    @InProceedings{SmallRosichMeierNueesch04:ASARGeoloc,
    Title = {{Geometric Calibration and Validation of ASAR Imagery}},
    Author = {David Small and Betlem Rosich and Erich Meier and Daniel N{\"u}esch},
    Booktitle = {CEOS SAR Workshop 2004},
    Month = May,
    Year = {2004},
    Abstract = {We describe work conducted to calibrate and then validate the geometry of ENVISAT ASAR products. A systematic error in range location was observed in ASAR products during the commissioning phase. A careful and complete analysis has been performed to establish the precise error. It has been compensated by updating the range gate bias (or sampling window start time bias). Validation of the absolute location accuracy of most ASAR products was performed subsequently. The location of surveyed targets is predicted using the satellite state vectors and ancillary timing information via the range and Doppler equations. The prediction's accuracy is affected by instrument bias, ionospheric and atmospheric path delay, as well as target survey errors. Transponders are in addition subject to internal delay uncertainty. The positions of the strong transponder and corner reflector targets in the images are measured to sub-sample accuracy by employing large oversampling factors. Initial and residual bias determinations were made using image acquisitions covering transponders and corner reflectors in the Netherlands, Canada, and Switzerland. Using a large number of independent targets helps reduce the influence of their independent survey errors. The highest resolution slant range single look complex (SLC) products (IMS, APS) were mainly used for testing. In addition, absolute location error was also measured on selected ground range products (IMP, APP, IMM, APM, WSM). Some ground range products also require treatment of multiple slant/ground range polynomials - proper handling is validated. For all test cases processed with precise orbits to date, the residual bias in the slant range direction has been smaller than the size of a single range sample. Predictability of target image location within ASAR image products is very high - better than experience with ERS-1/2, JERS-1, and RADARSAT-1. This result is encouraging, as it opens possibilities for ground control point (GCP) free terrain-geocoding and simplified interferometric processing.},
    Address = {Ulm},
    Day = {27-28},
    Keywords = {SAR Geocoding, Calibration, Validation, Quality Assessment, ASAR, ENVISAT},
    Pdf = {../../../docs/SmallRosichMeierNueesch04.pdf} 
    }
    


  30. David Small, Betlem Rosich, Adrian Schubert, Erich Meier, and Daniel Nüesch. Geometric Validation of Low and High-Resolution ASAR Imagery. In Proc. of the 2004 Envisat & ERS Symposium, ESA SP-572, Salzburg, Sep. 2004. Keyword(s): SAR Processing, SAR Geocoding, Geocoding, Validation, Geometric Validation, ASAR, ENVISAT.
    @InProceedings{smallRosichSchubertMeierNueesch04:SubmittedBistatic,
    Title = {{Geometric Validation of Low and High-Resolution ASAR Imagery}},
    Author = {David Small and Betlem Rosich and Adrian Schubert and Erich Meier and Daniel N{\"u}esch},
    Booktitle = {Proc. of the 2004 Envisat \& ERS Symposium},
    Month = {Sep.},
    Series = {ESA SP-572},
    Year = {2004},
    Address = {Salzburg},
    Day = {6-10},
    Keywords = {SAR Processing, SAR Geocoding,Geocoding, Validation, Geometric Validation, ASAR, ENVISAT},
    Owner = {ofrey} 
    }
    


  31. Junfeng Wang and Xingzhao Liu. SAR Automatic Range-Migration Correction. In IGARSS '04, International Geoscience and Remote Sensing Symposium, September 2004. Keyword(s): SAR Processing, range-Doppler Algorithm, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Migration Correction.
    Abstract: A new idea is presented to correct range migration in SAR imaging. In the range-Doppler domain, all the samples at a given Doppler frequency constitute a Doppler slice. Different Doppler slices are found to have similar envelopes. According to this similarity, the Doppler slices are shifted in range to correct range migration. This technique applies even without the prior information about the relative motion between the radar and the target.

    @InProceedings{WangLiu04:RangeMigration,
    Title = {{SAR Automatic Range-Migration Correction}},
    Author = {Junfeng Wang and Xingzhao Liu},
    Booktitle = {IGARSS '04, International Geoscience and Remote Sensing Symposium},
    Month = sep,
    Year = {2004},
    Abstract = {A new idea is presented to correct range migration in SAR imaging. In the range-Doppler domain, all the samples at a given Doppler frequency constitute a Doppler slice. Different Doppler slices are found to have similar envelopes. According to this similarity, the Doppler slices are shifted in range to correct range migration. This technique applies even without the prior information about the relative motion between the radar and the target.},
    Keywords = {SAR Processing, range-Doppler Algorithm, omega-k, Range Migration Algorithm, Wavenumber Domain Algorithm, Range-Migration Correction},
    Pdf = {../../../docs/WangLiu04.pdf} 
    }
    


Internal reports

  1. Betlem Rosich and Peter Meadows. Absolute Calibration of ASAR Level 1 Products Generated with PF-ASAR. Technical report Iss. 1 rev. 5, ESA, Oct. 2004. Keyword(s): ASAR, ENVISAT, Calibration, Validation, Product Calibration, Quality Measures, Quality Assessment, Level 1 Products, SAR.
    Abstract: The aim of this document is to describe the absolute calibration of high rate ASAR Level 1 products generated by ESA using the ASAR processing Facility (PF-ASAR). ESA ASAR level 1 products are generated at the Processing and Archiving Centres (PACs) and at the acquisitions stations: D-PAC, I-PAC, UK-PAC, PDHS-K (Kiruna), PDHS-E (Esrin). Since the same processor is used in all facilities, a unique methodology is described here, which is applicable to any product regardless of where it has been generated. The document is organised as follows: Section 3 describes the derivation of sigma and gamma nought over distributed targets. Section 4 presents the estimation of point targets Radar Cross Section. Annex A provides a procedure to derive the elevation angle for each image pixel, which is a key parameter for the absolute product calibration. Annex B describes how to perform the elevation antenna pattern correction, which is required for complex products calibration. Annex C defines the parameters required for the above operations. Annex D is provided for reference. It presents the evolution of the elevation antenna pattern since Aug. 2002.
    Comments: Reference: ENVI-CLVL-EOPG-TN-03-0010, Issue 1, revision 5, 07. Oct 2004

    @TechReport{RosichMeadows04:ASAR,
    Title = {{Absolute Calibration of ASAR Level 1 Products Generated with PF-ASAR}},
    Author = {Betlem Rosich and Peter Meadows},
    Institution = {ESA},
    Month = {Oct.},
    Number = {Iss. 1 rev. 5},
    Year = {2004},
    Abstract = {The aim of this document is to describe the absolute calibration of high rate ASAR Level 1 products generated by ESA using the ASAR processing Facility (PF-ASAR). ESA ASAR level 1 products are generated at the Processing and Archiving Centres (PACs) and at the acquisitions stations: D-PAC, I-PAC, UK-PAC, PDHS-K (Kiruna), PDHS-E (Esrin). Since the same processor is used in all facilities, a unique methodology is described here, which is applicable to any product regardless of where it has been generated. The document is organised as follows: Section 3 describes the derivation of sigma and gamma nought over distributed targets. Section 4 presents the estimation of point targets Radar Cross Section. Annex A provides a procedure to derive the elevation angle for each image pixel, which is a key parameter for the absolute product calibration. Annex B describes how to perform the elevation antenna pattern correction, which is required for complex products calibration. Annex C defines the parameters required for the above operations. Annex D is provided for reference. It presents the evolution of the elevation antenna pattern since Aug. 2002.},
    Comments = {Reference: ENVI-CLVL-EOPG-TN-03-0010, Issue 1, revision 5, 07. Oct 2004},
    Day = {7},
    Keywords = {ASAR, ENVISAT, Calibration, Validation, Product Calibration, Quality Measures, Quality Assessment,Level 1 Products, SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/ASARproductsabsolutecalibrationv1.5.pdf} 
    }
    


Miscellaneous

  1. Daniel Svensson and Jan Johansson. Suppression of Radio Frequency Interference in Low Frequency SAR. Master's thesis, Chalmers University of Technology, 2004. Keyword(s): SAR Processing, RFI Suppression, CARABAS, Airborne SAR, Analogue TV, VHF SAR.
    Abstract: To acquire high resolution in airborne radar imaging, either minuscule wavelengths or incredibly large antennas must be used. Another way of solving that issue is to utilise moving radar to realise the effect of a large aperture; a technique called synthetic aperture radar (SAR). CARABAS is a low frequency SAR system, operating in the band of 20 ? 90 MHz, designed to minimise the influence from speckle by using wavelengths of the same order as the resolution cells of the ground image. Radio frequency interference (RFI) is, however, highly prevalent in that frequency band, and must be filtered before the SAR image formation is initialised. The purpose of this thesis is to investigate a proposed method of suppressing RFI, particularly from analogue TV, with a technique based on Doppler compression filtering, to conclude if that technique is applicable. The technique is based on the fact that temporal variations in the TV signal can be predicted. Thus, by synchronising the radar transmission to the line synchronisation pulse of the TV signal, the interference after pulse compression will be concentrated to a component at DC and components at the field rate and its harmonics, in the slow time unfolding of radar data, which enables efficient notch filtering in the range and Doppler domains. The thesis has been carried out at Ericsson Microwave Systems AB in M?lndal, under the supervision of Dr. Hans Hellsten, the originator of CARABAS. The thesis work comprised thorough literature studies, profound measurements of DVD signals, representing ordinary TV signals, implementation of the proposed RFI suppression system in MATLAB, and analysis of the system, regarding attained suppression for different parameter sets. From the results of the thesis it can be concluded that the suppression technique is indeed applicable, but that not all parameter sets provide the required mitigation of 30 dB. That requirement was only fulfilled for two cases: for one second of integration time, together with 4 Hz null-to-null notch widths, and for two seconds of integration time, together with 2 Hz notch widths ? both with a PRF of 15 kHz and a complete Doppler band-pass filtering outside the interval of ?100 to 100 Hz.

    @MastersThesis{svenssonJohansson04:RFI,
    Title = {Suppression of Radio Frequency Interference in Low Frequency SAR},
    Author = {Daniel Svensson and Jan Johansson},
    Year = {2004},
    Abstract = {To acquire high resolution in airborne radar imaging, either minuscule wavelengths or incredibly large antennas must be used. Another way of solving that issue is to utilise moving radar to realise the effect of a large aperture; a technique called synthetic aperture radar (SAR). CARABAS is a low frequency SAR system, operating in the band of 20 ? 90 MHz, designed to minimise the influence from speckle by using wavelengths of the same order as the resolution cells of the ground image. Radio frequency interference (RFI) is, however, highly prevalent in that frequency band, and must be filtered before the SAR image formation is initialised. The purpose of this thesis is to investigate a proposed method of suppressing RFI, particularly from analogue TV, with a technique based on Doppler compression filtering, to conclude if that technique is applicable. The technique is based on the fact that temporal variations in the TV signal can be predicted. Thus, by synchronising the radar transmission to the line synchronisation pulse of the TV signal, the interference after pulse compression will be concentrated to a component at DC and components at the field rate and its harmonics, in the slow time unfolding of radar data, which enables efficient notch filtering in the range and Doppler domains. The thesis has been carried out at Ericsson Microwave Systems AB in M?lndal, under the supervision of Dr. Hans Hellsten, the originator of CARABAS. The thesis work comprised thorough literature studies, profound measurements of DVD signals, representing ordinary TV signals, implementation of the proposed RFI suppression system in MATLAB, and analysis of the system, regarding attained suppression for different parameter sets. From the results of the thesis it can be concluded that the suppression technique is indeed applicable, but that not all parameter sets provide the required mitigation of 30 dB. That requirement was only fulfilled for two cases: for one second of integration time, together with 4 Hz null-to-null notch widths, and for two seconds of integration time, together with 2 Hz notch widths ? both with a PRF of 15 kHz and a complete Doppler band-pass filtering outside the interval of ?100 to 100 Hz.},
    Keywords = {SAR Processing, RFI Suppression, CARABAS, Airborne SAR, Analogue TV, VHF SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/svenssonJohansson04.pdf},
    School = {Chalmers University of Technology} 
    }
    


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Please note that access to full text PDF versions of papers is restricted to the Chair of Earth Observation and Remote Sensing, Institute of Environmental Engineering, ETH Zurich.
Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright.

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




Last modified: Mon Feb 1 16:39:00 2021
Author: Othmar Frey, Earth Observation and Remote Sensing, Institute of Environmental Engineering, Swiss Federal Institute of Technology - ETH Zurich .


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