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Publications of year 1994

Books and proceedings

  1. Mehrdad Soumekh. Fourier Array Imaging. Englewood Cliffs, NJ: Prentice Hall, 1994. Keyword(s): SAR Processing, Fourier Array Imaging.
    @Book{soumekh:FourierArrayImaging1994,
    Title = {Fourier Array Imaging},
    Author = {Mehrdad Soumekh},
    Publisher = {Englewood Cliffs, NJ: Prentice Hall},
    Year = {1994},
    Keywords = {SAR Processing, Fourier Array Imaging},
    Owner = {ofrey} 
    }
    


Articles in journal or book chapters

  1. T. M. Calloway and G. W. Donohoe. Subaperture autofocus for synthetic aperture radar. IEEE Transactions on Aerospace and Electronic Systems, 30(2):617-621, 1994. Keyword(s): SAR Processing, Autofocus.
    Abstract: A subaperture autofocus algorithm for synthetic aperture radar (SAR) partitions range-compressed phase-history data collected over a full aperture into equal-width subapertures. Application of a one-dimensional Fourier transform to each range bin converts each subaperture data set into a full-scene image (map). Any linear phase difference, or phase ramp, between a pair of subapertures expresses itself as cross-range drift in their maps. A traditional autofocus algorithm fits a polynomial to inferred equal-width phase ramps. If the true phase error function contains significant high-order components, then polynomial regression generates a poor estimate of the phase error function. Instead of filling a polynomial, we fit a sinusoidal function through the inferred phase ramps. An example with a degraded SAR image shows how a sinusoidal correction improves image quality. We compare lower bounds on mean squared error (MSE) for polynomial and sinusoidal parameterizations. Sinusoidal parameterization reduces MSE significantly for model orders greater than five.

    @Article{callowayDonohoeTAES1994SubapertureAutofocusForSyntheticAperureRadar,
    author = {T. M. {Calloway} and G. W. {Donohoe}},
    journal = {IEEE Transactions on Aerospace and Electronic Systems},
    title = {Subaperture autofocus for synthetic aperture radar},
    year = {1994},
    number = {2},
    pages = {617-621},
    volume = {30},
    abstract = {A subaperture autofocus algorithm for synthetic aperture radar (SAR) partitions range-compressed phase-history data collected over a full aperture into equal-width subapertures. Application of a one-dimensional Fourier transform to each range bin converts each subaperture data set into a full-scene image (map). Any linear phase difference, or phase ramp, between a pair of subapertures expresses itself as cross-range drift in their maps. A traditional autofocus algorithm fits a polynomial to inferred equal-width phase ramps. If the true phase error function contains significant high-order components, then polynomial regression generates a poor estimate of the phase error function. Instead of filling a polynomial, we fit a sinusoidal function through the inferred phase ramps. An example with a degraded SAR image shows how a sinusoidal correction improves image quality. We compare lower bounds on mean squared error (MSE) for polynomial and sinusoidal parameterizations. Sinusoidal parameterization reduces MSE significantly for model orders greater than five.},
    doi = {10.1109/7.272285},
    file = {:callowayDonohoeTAES1994SubapertureAutofocusForSyntheticAperureRadar.pdf:PDF},
    keywords = {SAR Processing, Autofocus},
    owner = {ofrey},
    
    }
    


  2. Giorgio Franceschetti, Maurizio Migliaccio, and Daniele Riccio. SAR Raw Signal Simulation of Actual Ground Sites Described in Terms of Sparse Input Data. IEEE Transactions on Geoscience and Remote Sensing, 32(6):1160-1169, November 1994. Keyword(s): SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Fractals, Sparse Input Data, SARAS.
    Abstract: Deals with the simulation of synthetic aperture radar (SAR) raw signal of actual ground sites described in terms of sparse input data. Since in most cases the input data reference system does not match SAR requirements, it is necessary to adopt appropriate interpolation schemes. The authors focus their attention on elevation input data, noting that natural surfaces exhibit fractal properties. Fractal and nonfractal interpolation schemes are discussed and applied. Simulated images are shown and compared to actual examples. Subjective and objective tests validate the simulation and support the fractal-based elevation interpolation.

    @Article{francescMigliaRiccio94:Simulation,
    Title = {{SAR Raw Signal Simulation of Actual Ground Sites Described in Terms of Sparse Input Data}},
    Author = {Giorgio Franceschetti and Maurizio Migliaccio and Daniele Riccio},
    Month = Nov,
    Number = {6},
    Pages = {1160-1169},
    Url = {http://ieeexplore.ieee.org/iel1/36/7937/00338364.pdf},
    Volume = {32},
    Year = {1994},
    Abstract = {Deals with the simulation of synthetic aperture radar (SAR) raw signal of actual ground sites described in terms of sparse input data. Since in most cases the input data reference system does not match SAR requirements, it is necessary to adopt appropriate interpolation schemes. The authors focus their attention on elevation input data, noting that natural surfaces exhibit fractal properties. Fractal and nonfractal interpolation schemes are discussed and applied. Simulated images are shown and compared to actual examples. Subjective and objective tests validate the simulation and support the fractal-based elevation interpolation.},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Simulation, SAR Simulator, Raw Data Simulator, Fractals, Sparse Input Data, SARAS},
    Pdf = {../../../docs/francescMigliaRiccio94.pdf} 
    }
    


  3. Fabio Gatelli, Andrea Monti-Guarnieri, Francesco Parizzi, Paolo Pasquali, Claudio Prati, and Fabio Rocca. The wavenumber shift in SAR interferometry. IEEE Transactions on Geoscience and Remote Sensing, 32(4):855-865, July 1994. Keyword(s): SAR Processing, SAR Interferometry, Interferometry, InSAR, Range Spectral Filter, geophysical techniques, remote sensing by radar, synthetic aperture radar, TINSAR, decorrelation reduction, Baseline Decorrelation, geophysical measurement technique, ground wavenumber spectra, land surface, local slope, low noise interferogram, off-nadir angle, phase unwrapping, quick-look interferogram, radar imaging, range resolution enhancement, relative shift, remote sensing, spectral shift, terrain mapping, wavenumber shift.
    Abstract: SAR surveys from separate passes show relative shifts of the ground wavenumber spectra that depend on the local slope and the off-nadir angle. The authors discuss the exploitation of this spectral shift for different applications: 1) generation of \u201clow noise\u201d interferograms benefiting phase unwrapping, 2) generation of quick-look interferograms, 3) decorrelation reduction by means of tunable SAR systems (TINSAR), 4) range resolution enhancement, and 5) the combination of SAR data gathered by different platforms (airborne and satellite) for a \u201clong-time coherence\u201d study

    @Article{gatelliMontiGuarnieriParizziPasqualiPratiRocca1994:InSARWavenumberShift,
    Title = {{The wavenumber shift in SAR interferometry}},
    Author = {Gatelli, Fabio and Monti-Guarnieri, Andrea and Parizzi, Francesco and Pasquali, Paolo and Prati, Claudio and Rocca, Fabio},
    Doi = {10.1109/36.298013},
    ISSN = {0196-2892},
    Month = {jul},
    Number = {4},
    Pages = {855--865},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=298013&isnumber=7386},
    Volume = {32},
    Year = {1994},
    Abstract = {SAR surveys from separate passes show relative shifts of the ground wavenumber spectra that depend on the local slope and the off-nadir angle. The authors discuss the exploitation of this spectral shift for different applications: 1) generation of \u201clow noise\u201d interferograms benefiting phase unwrapping, 2) generation of quick-look interferograms, 3) decorrelation reduction by means of tunable SAR systems (TINSAR), 4) range resolution enhancement, and 5) the combination of SAR data gathered by different platforms (airborne and satellite) for a \u201clong-time coherence\u201d study},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, SAR Interferometry, Interferometry, InSAR, Range Spectral Filter, geophysical techniques, remote sensing by radar, synthetic aperture radar, TINSAR, decorrelation reduction, Baseline Decorrelation, geophysical measurement technique, ground wavenumber spectra, land surface, local slope, low noise interferogram, off-nadir angle, phase unwrapping, quick-look interferogram, radar imaging, range resolution enhancement, relative shift, remote sensing, spectral shift, terrain mapping, wavenumber shift},
    Owner = {ofrey},
    Pdf = {../../../docs/gatelliMontiGuarnieriParizziPasqualiPratiRocca1994.pdf} 
    }
    


  4. Dieter Just and Richard Bamler. Phase Statistics of Interferograms with Applications to Synthetic Aperture Radar. Applied Optics, 33(20):4361-4368, July 1994. Keyword(s): SAR Processing, InSAR, Interferometry, SAR Interferometry, Phase Statistics, Decorrelation, Aberrations, Wavenumber Shift, Coregistration.
    Abstract: Interferometric methods are well established in optics and radio astronomy. In recent years, interferometric concepts have been applied successfully to synthetic aperture radar (SAR) and have opened up new possibilities in the area of earth remote sensing. However interferometric SAR applications require thorough phase control through the imaging process. The phase accuracy of SAR images is affected by decorrelation effects between the individual surveys. We analyze quantitatively the influence of decorrelation on the phase statistics of SAR interferograms. In particular, phase aberrations as they occur in typical SAR processors are studied in detail. The dependence of the resulting phase bias and variance on processor parameters is presented in several diagrams.

    @Article{justBamler94,
    author = {Dieter Just and Richard Bamler},
    journal = {Applied Optics},
    title = {{Phase Statistics of Interferograms with Applications to Synthetic Aperture Radar}},
    year = {1994},
    month = {jul},
    number = {20},
    pages = {4361-4368},
    volume = {33},
    abstract = {Interferometric methods are well established in optics and radio astronomy. In recent years, interferometric concepts have been applied successfully to synthetic aperture radar (SAR) and have opened up new possibilities in the area of earth remote sensing. However interferometric SAR applications require thorough phase control through the imaging process. The phase accuracy of SAR images is affected by decorrelation effects between the individual surveys. We analyze quantitatively the influence of decorrelation on the phase statistics of SAR interferograms. In particular, phase aberrations as they occur in typical SAR processors are studied in detail. The dependence of the resulting phase bias and variance on processor parameters is presented in several diagrams.},
    file = {:justBamler94.pdf:PDF},
    keywords = {SAR Processing, InSAR, Interferometry, SAR Interferometry, Phase Statistics, Decorrelation, Aberrations, Wavenumber Shift, Coregistration},
    owner = {ofrey},
    pdf = {../../../docs/justBamler94.pdf},
    url = {http://www.opticsinfobase.org/viewmedia.cfm?uri=ao-33-20-4361&seq=0},
    
    }
    


  5. J. S. Lee, M. R. Grunes, and Ron Kwok. Classification of multi-look polarimetric SAR imagery based on complex Wishart distribution. International Journal of Remote Sensing, 15(11):2299-2311, 1994.
    Abstract: Multi-look polarimetric SAR (synthetic aperture radar) data can be represented either in Mueller matrix form or in complex covariance matrix form. The latter has a complex Wishart distribution. A maximum likelihood classifier to segment polarimetric SAR data according to terrain types has been developed based on the Wishart distribution. This algorithm can also be applied to multifrequency multi-look polarimetric SAR data, as well as 10 SAR data containing only intensity information. A procedure is then developed for unsupervised classification. The classification error is assessed by using Monte Carlo simulation of multilook polarimetric SAR data, owing to the lack of ground truth for each pixel. Comparisons of classification errors using the training sets and single-look data are also made. Applications of this algorithm are demonstrated with NASA/JPL P-, L- and C-band polarimetric SAR data.

    @Article{leeGrunesKwokIJRS1994ClassificationMLPolarimetricSARImagery,
    author = {J. S. Lee and M. R. Grunes and Ron Kwok},
    title = {Classification of multi-look polarimetric {SAR} imagery based on complex {W}ishart distribution},
    journal = {International Journal of Remote Sensing},
    year = {1994},
    volume = {15},
    number = {11},
    pages = {2299-2311},
    abstract = {Multi-look polarimetric SAR (synthetic aperture radar) data can be represented either in Mueller matrix form or in complex covariance matrix form. The latter has a complex Wishart distribution. A maximum likelihood classifier to segment polarimetric SAR data according to terrain types has been developed based on the Wishart distribution. This algorithm can also be applied to multifrequency multi-look polarimetric SAR data, as well as 10 SAR data containing only intensity information. A procedure is then developed for unsupervised classification. The classification error is assessed by using Monte Carlo simulation of multilook polarimetric SAR data, owing to the lack of ground truth for each pixel. Comparisons of classification errors using the training sets and single-look data are also made. Applications of this algorithm are demonstrated with NASA/JPL P-, L- and C-band polarimetric SAR data.},
    doi = {10.1080/01431169408954244},
    eprint = {https://doi.org/10.1080/01431169408954244},
    owner = {ofrey},
    publisher = {Taylor \& Francis},
    url = {https://doi.org/10.1080/01431169408954244},
    
    }
    


  6. Jong-Sen Lee, K. W. Hoppel, S. A. Mango, and A. R. Miller. Intensity and phase statistics of multilook polarimetric and interferometric SAR imagery. IEEE Trans. Geosci. Remote Sens., 32(5):1017-1028, September 1994. Keyword(s): feature extraction, geophysical techniques, geophysics computing, image coding, image recognition, remote sensing by radar, synthetic aperture radar, complex correlation coefficient, data compression, decorrelation effects, feature classification, feature extraction, geophysical measurement technique, image classification, intensity statistics, interferometric SAR imagery, land surface imaging, multilook phase difference, multilook polarimetry, phase statistics, probability density function, radar remote sensing, scattering matrix, signal processing, speckle reduction, synthetic aperture radar, Covariance matrix, Decorrelation, Density functional theory, NASA, Phase measurement, Radar polarimetry, Radar scattering, Sea measurements, Speckle, Statistics.
    Abstract: Polarimetric and interferometric SAR data are frequently multilook processed for speckle reduction and data compression. The statistical characteristics of multilook data are quite different from those of single-look data. The authors investigate the statistics of their intensity and phase. Probability density function (PDF's) of the multilook phase difference, magnitude of complex product, and intensity and amplitude ratios between two components of the scattering matrix are derived, and expressed in closed forms. The PDF's depend on the complex correlation coefficient and the number of looks. Comparisons of these theoretically derived PDF's are made to measurements from NASA/JPL AIRSAR data. The results of this paper can be applied to feature classification using polarimetric SAR and to the estimation of decorrelation effects of the interferometric SAR

    @Article{leeHoppelMangoMillerTGRS1994IntensityAndPhaseStatisticsMLPolarimetricAndInSARImagery,
    author = {Jong-Sen Lee and K. W. Hoppel and S. A. Mango and A. R. Miller},
    title = {Intensity and phase statistics of multilook polarimetric and interferometric {SAR} imagery},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {1994},
    volume = {32},
    number = {5},
    pages = {1017-1028},
    month = sep,
    issn = {0196-2892},
    abstract = {Polarimetric and interferometric SAR data are frequently multilook processed for speckle reduction and data compression. The statistical characteristics of multilook data are quite different from those of single-look data. The authors investigate the statistics of their intensity and phase. Probability density function (PDF's) of the multilook phase difference, magnitude of complex product, and intensity and amplitude ratios between two components of the scattering matrix are derived, and expressed in closed forms. The PDF's depend on the complex correlation coefficient and the number of looks. Comparisons of these theoretically derived PDF's are made to measurements from NASA/JPL AIRSAR data. The results of this paper can be applied to feature classification using polarimetric SAR and to the estimation of decorrelation effects of the interferometric SAR},
    doi = {10.1109/36.312890},
    keywords = {feature extraction;geophysical techniques;geophysics computing;image coding;image recognition;remote sensing by radar;synthetic aperture radar;complex correlation coefficient;data compression;decorrelation effects;feature classification;feature extraction;geophysical measurement technique;image classification;intensity statistics;interferometric SAR imagery;land surface imaging;multilook phase difference;multilook polarimetry;phase statistics;probability density function;radar remote sensing;scattering matrix;signal processing;speckle reduction;synthetic aperture radar;Covariance matrix;Decorrelation;Density functional theory;NASA;Phase measurement;Radar polarimetry;Radar scattering;Sea measurements;Speckle;Statistics},
    owner = {ofrey},
    
    }
    


  7. V.K. Madisetti. A fast spotlight-mode synthetic aperture radar imaging system. IEEE Transactions on Communications, 42(234):873-876, February 1994. Keyword(s): SAR Processing, Back-Projection, Tomography, Radon Transform, Spotlight SAR.
    Abstract: The author reformulates the standard spotlight mode synthetic aperture radar (SAR) problem as a ( tau;,p) Radon transform. This results in a new algorithm for SAR that uses a linear chirp FM source signal that is a function of the geometry between the source and the object. While the close relation between computer-aided-tomography (CAT) and SAR has been understood for over a decade, no accompanying computational advantages could be realized. Recently, Kelley and Madisetti (1991), have proposed a new approach to image reconstruction from projections using the so-called fast Radon transform (FRT). He derives, in the ( tau;,p) domain, a FRT-based solution to the SAR problem. The FRT offers implicit interpolation and parallel processing advantages not found in conventional back projection operations. He proposes its efficient application in the computationally intensive problems in telecommunications and remote sensing, especially in military applications

    @Article{580192,
    Title = {A fast spotlight-mode synthetic aperture radar imaging system},
    Author = {Madisetti, V.K.},
    Doi = {10.1109/TCOMM.1994.580192},
    ISSN = {0090-6778},
    Month = feb,
    Number = {234},
    Pages = {873-876},
    Volume = {42},
    Year = {1994},
    Abstract = {The author reformulates the standard spotlight mode synthetic aperture radar (SAR) problem as a ( tau;,p) Radon transform. This results in a new algorithm for SAR that uses a linear chirp FM source signal that is a function of the geometry between the source and the object. While the close relation between computer-aided-tomography (CAT) and SAR has been understood for over a decade, no accompanying computational advantages could be realized. Recently, Kelley and Madisetti (1991), have proposed a new approach to image reconstruction from projections using the so-called fast Radon transform (FRT). He derives, in the ( tau;,p) domain, a FRT-based solution to the SAR problem. The FRT offers implicit interpolation and parallel processing advantages not found in conventional back projection operations. He proposes its efficient application in the computationally intensive problems in telecommunications and remote sensing, especially in military applications},
    Journal = {IEEE Transactions on Communications},
    Keywords = {SAR Processing, Back-Projection, Tomography, Radon Transform, Spotlight SAR} 
    }
    


  8. Didier Massonnet, F. Adragna, and M. Rossi. CNES general-purpose SAR correlator. IEEE Trans. Geosci. Remote Sens., 32(3):636-643, 1994. Keyword(s): SAR Processing, Presumming, geophysical techniques, geophysics computing, image processing, remote sensing, remote sensing by radar, synthetic aperture radar, CNES general-purpose SAR correlator, constant phase reference, contrast seeker, data presumming, fast Fourier transform, frequency azimuth frequency domain, geophysical measurement technique, interferometry, land surface, migration compensation, multilooking, polynomial law generator, quick look, radar remote sensing, radiometric equalization map, signal processing, software, standard single look complex product, synthetic aperture radar, terrain mapping.
    Abstract: CNES has designed a new SAR correlator to process both airborne

    @Article{massonnetAdragnaRossi94:Presumming,
    Title = {CNES general-purpose SAR correlator},
    Author = {Massonnet, Didier and Adragna, F. and Rossi, M.},
    Number = {3},
    Pages = {636--643},
    Url = {http://ieeexplore.ieee.org/iel1/36/7385/00297981.pdf},
    Volume = {32},
    Year = {1994},
    Abstract = {CNES has designed a new SAR correlator to process both airborne},
    Journal = {IEEE Trans. Geosci. Remote Sens.},
    Keywords = {SAR Processing, Presumming, geophysical techniques, geophysics computing, image processing, remote sensing, remote sensing by radar, synthetic aperture radar, CNES general-purpose SAR correlator, constant phase reference, contrast seeker, data presumming, fast Fourier transform, frequency azimuth frequency domain, geophysical measurement technique, interferometry, land surface, migration compensation, multilooking, polynomial law generator, quick look, radar remote sensing, radiometric equalization map, signal processing, software, standard single look complex product, synthetic aperture radar, terrain mapping},
    Owner = {ofrey},
    Pdf = {../../../docs/massonnetAdragnaRossi94.pdf} 
    }
    


  9. Didier Massonnet, Kurt Feigl, Marc Rossi, and Frederic Adragna. Radar interferometric mapping of deformation in the year after the Landers earthquake. Nature, 369(6477):227-230, May 1994. Keyword(s): SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Earthquake, Landers earthquake, Fault Slip.
    Abstract: Altough the 1992 Landers, California, earthquake sequence occurred in an area well sampled by geodetic networks, the postseismic deformation in the months following the earthquake has been measured at only 15 geodetic stations. Another shortcoming in the geodetic coverage occurs west of the primary rupture, where the existing geodetic observations suggest, but cannot resolve, sympathetic slip on secondary faults. Such measurements, which are needed to place the Landers earthquake sequence in the context of a recurring seismic cycle in California, can be obtained with the dense spatial coverage provided by satellite radar interferometry. Here we present radar maps of the surface deformation field which reveal features that would otherwise have been poorly sampled, particularly if the earthquake had occurred in a less accessible area. We see triggered slip at the level of several centimetres as far as 100 km from the primary rupture, and can resolve the geodetic signal of at least one small (magnitude 5) aftershock. The amount of surface slip following the main shock is less than a decimetre, and is consistent with an exponential decay time of several months for the postseismic deformation.

    @Article{massonnetFeiglRossiAdragnaNature1994DINSARLandersEQuake,
    author = {Massonnet, Didier and Feigl, Kurt and Rossi, Marc and Adragna, Frederic},
    journal = {Nature},
    title = {Radar interferometric mapping of deformation in the year after the {Landers} earthquake},
    year = {1994},
    month = may,
    number = {6477},
    pages = {227--230},
    volume = {369},
    abstract = {Altough the 1992 Landers, California, earthquake sequence occurred in an area well sampled by geodetic networks, the postseismic deformation in the months following the earthquake has been measured at only 15 geodetic stations. Another shortcoming in the geodetic coverage occurs west of the primary rupture, where the existing geodetic observations suggest, but cannot resolve, sympathetic slip on secondary faults. Such measurements, which are needed to place the Landers earthquake sequence in the context of a recurring seismic cycle in California, can be obtained with the dense spatial coverage provided by satellite radar interferometry. Here we present radar maps of the surface deformation field which reveal features that would otherwise have been poorly sampled, particularly if the earthquake had occurred in a less accessible area. We see triggered slip at the level of several centimetres as far as 100 km from the primary rupture, and can resolve the geodetic signal of at least one small (magnitude 5) aftershock. The amount of surface slip following the main shock is less than a decimetre, and is consistent with an exponential decay time of several months for the postseismic deformation.},
    doi = {10.1038/369227a0},
    file = {:massonnetFeiglRossiAdragnaNature1994DINSARLandersEQuake.pdf:PDF},
    keywords = {SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Earthquake, Landers earthquake, Fault Slip},
    owner = {ofrey},
    pdf = {../../../docs/massonnetFeiglRossiAdragnaNature1994DINSARLandersEQuake.pdf},
    url = {http://dx.doi.org/10.1038/369227a0},
    
    }
    


  10. Christian Matzler. Microwave (1-100 GHz) dielectric model of leaves. IEEE Transactions on Geoscience and Remote Sensing, 32(4):947-949, 1994.
    @Article{Matzler1994,
    author = {Matzler, Christian},
    title = {Microwave (1-100 GHz) dielectric model of leaves},
    journal = {IEEE Transactions on Geoscience and Remote Sensing},
    year = {1994},
    volume = {32},
    number = {4},
    pages = {947--949},
    owner = {ofrey},
    publisher = {IEEE},
    
    }
    


  11. Alberto Moreira and Yonghong Huang. Airborne SAR Processing of Highly Squinted Data Using a Chirp Scaling Approach with Integrated Motion Compensation. IEEE Transactions on Geoscience and Remote Sensing, 32(5):1029-1040, September 1994. Keyword(s): SAR Processing, Chirp Scaling Algorithm, Extended Chirp Scaling Algorithm, Motion Compensation, Motion Estimation, Squinted SAR, Cubic Phase Term, Airborne SAR, Automatic Azimuth Coregistration, Azimuth Scaling, Squinted SAR, Interferometry, Phase-Preserving Processing, Range Scaling Formulation, Stripmap SAR, Subaperture Processing, Terrain Mapping.
    Abstract: Proposes a new approach for high-resolution airborne SAR data processing, which uses a modified chirp scaling algorithm to accommodate the correction of motion errors, as well as the variations of the Doppler centroid in range and azimuth. By introducing a cubic phase term in the chirp scaling phase, data acquired with a squint angle up to 30? can be processed with no degradation of the impulse response function. The proposed approach is computationally very efficient, since it accommodates the variations of Doppler centroid without using block processing. Furthermore, a motion error extraction algorithm can be incorporated into the proposed approach by means of subaperture processing in azimuth. The new approach, denoted as extended chirp scaling, is considered to be a generalized algorithm suitable for the high-resolution processing of most airborne SAR systems.

    @Article{moreiraHuang94:ChirpScaling,
    Title = {{Airborne SAR Processing of Highly Squinted Data Using a Chirp Scaling Approach with Integrated Motion Compensation}},
    Author = {Alberto Moreira and Yonghong Huang},
    Month = sep,
    Number = {5},
    Pages = {1029-1040},
    Url = {http://ieeexplore.ieee.org/iel1/36/7578/00312891.pdf},
    Volume = {32},
    Year = {1994},
    Abstract = {Proposes a new approach for high-resolution airborne SAR data processing, which uses a modified chirp scaling algorithm to accommodate the correction of motion errors, as well as the variations of the Doppler centroid in range and azimuth. By introducing a cubic phase term in the chirp scaling phase, data acquired with a squint angle up to 30? can be processed with no degradation of the impulse response function. The proposed approach is computationally very efficient, since it accommodates the variations of Doppler centroid without using block processing. Furthermore, a motion error extraction algorithm can be incorporated into the proposed approach by means of subaperture processing in azimuth. The new approach, denoted as extended chirp scaling, is considered to be a generalized algorithm suitable for the high-resolution processing of most airborne SAR systems.},
    Comment = {+ Paper discusses a variation of Chirp Scaling. See [RRB+94].},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Chirp Scaling Algorithm, Extended Chirp Scaling Algorithm, Motion Compensation, Motion Estimation, Squinted SAR, Cubic Phase Term, Airborne SAR, Automatic Azimuth Coregistration, Azimuth Scaling, Squinted SAR, Interferometry, Phase-Preserving Processing, Range Scaling Formulation, Stripmap SAR, Subaperture Processing, Terrain Mapping},
    Owner = {ofrey},
    Pdf = {../../../docs/moreiraHuang94.pdf} 
    }
    


  12. Shaun Quegan. A unified algorithm for phase and cross-talk calibration of polarimetric data-theory and observations. IEEE Trans. Geosci. Remote Sens., 32(1):89-99, January 1994. Keyword(s): SAR Processing, Polarimetry, Polarimetric Calibration, calibration, geophysical techniques, polarimetry, remote sensing, remote sensing by radar, MAESTRO campaign, agriculture, cross-polarized backscattering coefficient, cross-talk calibration, geophysical measurement technique, land surface SAR radar imaging, linear distortion model, minimum least squares, observation, phase, polarimetry, polarisation, scattering matrix, synthetic aperture radar, theory, unified algorithm, Backscatter, Calibration, Covariance matrix, Crosstalk, Data mining, Equations, Layout, Phase distortion, Scattering, System testing.
    Abstract: A unified approach to phase and cross-talk calibration of polarimetric data which can be applied to calibrating scattering matrix data or to extraction of the descriptors of distributed targets is described. It relies on the scene being dominated by targets with uncorrelated like and cross-polarized backscattering coefficients, but provides cross-talk calibration of targets for which this is not true. The algorithm needs unsymmetrized data, but uses only quantities derived from the covariance matrix of large areas. It makes no assumptions about system reciprocity, permits ready interpretation of the terms in the calibration procedure, allows comparison of the relative magnitude of the system-induced mixing of terms in the observed covariance matrix, is noniterative, and produces indicators which allow testing of whether it meets its own underlying assumptions. The linear distortion model is shown to lead to an inconsistent system of equations; this inconsistency can be removed by introducing an extra parameter which has properties expected of system noise. The modulus of the copolarized correlation coefficient, which is important in polarimetric classification and as a phase descriptor, is shown to be invariant under all effects embodied in the linear distortion model. Calibration of the scattering matrix data is based on a minimum least squares principle. This suggests that current methods of symmetrization are not optimal. The same analysis shows that estimates of parameters needed to form an equivalent reciprocal system are also nonoptimal. The method is more general than the well-known van Zyl algorithm for cross-talk removal, and permits an analysis of the conditions under which the van Zyl algorithm will yield valid results. Correction of phase distortion induced by channel imbalance Is treated as an optional extra step relying on a known HH-VV phase difference in some region of the image. Results from the algorithm are discussed using scattering matrix data from the 1989 MAESTRO campaign

    @Article{queganTGRS1994PolCalibration,
    author = {Quegan, Shaun},
    title = {A unified algorithm for phase and cross-talk calibration of polarimetric data-theory and observations},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {1994},
    volume = {32},
    number = {1},
    pages = {89-99},
    month = jan,
    issn = {0196-2892},
    abstract = {A unified approach to phase and cross-talk calibration of polarimetric data which can be applied to calibrating scattering matrix data or to extraction of the descriptors of distributed targets is described. It relies on the scene being dominated by targets with uncorrelated like and cross-polarized backscattering coefficients, but provides cross-talk calibration of targets for which this is not true. The algorithm needs unsymmetrized data, but uses only quantities derived from the covariance matrix of large areas. It makes no assumptions about system reciprocity, permits ready interpretation of the terms in the calibration procedure, allows comparison of the relative magnitude of the system-induced mixing of terms in the observed covariance matrix, is noniterative, and produces indicators which allow testing of whether it meets its own underlying assumptions. The linear distortion model is shown to lead to an inconsistent system of equations; this inconsistency can be removed by introducing an extra parameter which has properties expected of system noise. The modulus of the copolarized correlation coefficient, which is important in polarimetric classification and as a phase descriptor, is shown to be invariant under all effects embodied in the linear distortion model. Calibration of the scattering matrix data is based on a minimum least squares principle. This suggests that current methods of symmetrization are not optimal. The same analysis shows that estimates of parameters needed to form an equivalent reciprocal system are also nonoptimal. The method is more general than the well-known van Zyl algorithm for cross-talk removal, and permits an analysis of the conditions under which the van Zyl algorithm will yield valid results. Correction of phase distortion induced by channel imbalance Is treated as an optional extra step relying on a known HH-VV phase difference in some region of the image. Results from the algorithm are discussed using scattering matrix data from the 1989 MAESTRO campaign},
    doi = {10.1109/36.285192},
    file = {:queganTGRS1994PolCalibration.pdf:PDF},
    keywords = {SAR Processing, Polarimetry, Polarimetric Calibration;calibration;geophysical techniques;polarimetry;remote sensing;remote sensing by radar;MAESTRO campaign;agriculture;cross-polarized backscattering coefficient;cross-talk calibration;geophysical measurement technique;land surface SAR radar imaging;linear distortion model;minimum least squares;observation;phase;polarimetry;polarisation;scattering matrix;synthetic aperture radar;theory;unified algorithm;Backscatter;Calibration;Covariance matrix;Crosstalk;Data mining;Equations;Layout;Phase distortion;Scattering;System testing},
    pdf = {../../../docs/queganTGRS1994PolCalibration.pdf},
    
    }
    


  13. R. Keith Raney, Hartmut Runge, Richard Bamler, Ian G. Cumming, and Frank Wong. Precision SAR Processing Using Chirp Scaling. IEEE Transactions on Geoscience and Remote Sensing, 32(4):786-799, July 1994. Keyword(s): SAR Processing, Chirp Scaling Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Phase Preserving, Range-Doppler Algorithm, Comparison of Algorithms.
    Abstract: A space-variant interpolation is required to compensate for the migration of signal energy through range resolution cells when processing synthetic aperture radar (SAR) data, using either the classical range/Doppler (R/D) algorithm or related frequency domain techniques. In general, interpolation requires significant computation time, and leads to loss of image quality, especially in the complex image. The new chirp scaling algorithm avoids interpolation, yet performs range cell migration correction accurately. The algorithm requires only complex multiplies and Fourier transforms to implement, is inherently phase preserving, and is suitable for wide-swath, large-beamwidth, and large-squint applications. This paper describes the chirp scaling algorithm, summarizes simulation results, presents imagery processed with the algorithm, and reviews quantitative measures of its performance. Based on quantitative comparison, the chirp scaling algorithm provides image quality equal to or better than the precision range/Doppler processor. Over the range of parameters tested, image quality results approach the theoretical limit, as defined by the system bandwidth.

    @Article{RaneyRunBamCummWong94:Precision,
    Title = {{Precision SAR Processing Using Chirp Scaling}},
    Author = {R. Keith Raney and Hartmut Runge and Richard Bamler and Ian G. Cumming and Frank Wong},
    Month = jul,
    Number = {4},
    Pages = {786-799},
    Url = {http://ieeexplore.ieee.org/iel1/36/7386/00298008.pdf},
    Volume = {32},
    Year = {1994},
    Abstract = {A space-variant interpolation is required to compensate for the migration of signal energy through range resolution cells when processing synthetic aperture radar (SAR) data, using either the classical range/Doppler (R/D) algorithm or related frequency domain techniques. In general, interpolation requires significant computation time, and leads to loss of image quality, especially in the complex image. The new chirp scaling algorithm avoids interpolation, yet performs range cell migration correction accurately. The algorithm requires only complex multiplies and Fourier transforms to implement, is inherently phase preserving, and is suitable for wide-swath, large-beamwidth, and large-squint applications. This paper describes the chirp scaling algorithm, summarizes simulation results, presents imagery processed with the algorithm, and reviews quantitative measures of its performance. Based on quantitative comparison, the chirp scaling algorithm provides image quality equal to or better than the precision range/Doppler processor. Over the range of parameters tested, image quality results approach the theoretical limit, as defined by the system bandwidth.},
    Comment = {++ Paper introduces the Chirp Scaling algorithm},
    Journal = {IEEE Transactions on Geoscience and Remote Sensing},
    Keywords = {SAR Processing, Chirp Scaling Algorithm, Range Migration Algorithm, omega-k, Wavenumber Domain Algorithm, Phase Preserving, Range-Doppler Algorithm, Comparison of Algorithms},
    Pdf = {../../../docs/RaneyRunBamCummWong94.pdf} 
    }
    


  14. Andrew Reilly, Gordon Frazer, and Boualem Boashash. Analytic Signal Generation-Tips and Traps. Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on], 42(11):3241-3245, 1994. Keyword(s): Analytic Signal, Hilbert Transform, filtering theory, frequency estimation, parameter estimation, signal processing, signal synthesis, time-frequency analysis, Hilbert transform filters, analytic signal generation, discrete analytic signal, discrete real-valued signal, instantaneous-frequency estimation, modem designs, negative frequencies, positive frequencies, quadrature filters, time-frequency signal analysis.
    Abstract: In this correspondence we discuss methods to produce the discreteanalytic signal from a discrete real-valued signal. Such an analyticsignal is complex and contains only positive frequencies. Its projectiononto the real axis is the same as the original signal. Our use stemsfrom instantaneous-frequency estimation and time-frequency signalanalysis problems. For these problems the negative frequency componentof real signals causes unwanted interference. The task of designing afilter to produce an approximation to the ideal analytic signal is notas simple as its formulation might suggest. Our result is that thedirect methods of zeroing the negative frequencies, or using Hilberttransform filters, have undesirable defects. We present an alternative which is similar to the quadrature filters used in modemdesigns

    @Article{reillyFrazerBoashash94:AnalyticSignal,
    Title = {Analytic Signal Generation-Tips and Traps},
    Author = {Reilly, Andrew and Frazer, Gordon and Boashash, Boualem},
    Number = {11},
    Pages = {3241--3245},
    Url = {http://ieeexplore.ieee.org/iel4/78/7823/00330385.pdf},
    Volume = {42},
    Year = {1994},
    Abstract = {In this correspondence we discuss methods to produce the discreteanalytic signal from a discrete real-valued signal. Such an analyticsignal is complex and contains only positive frequencies. Its projectiononto the real axis is the same as the original signal. Our use stemsfrom instantaneous-frequency estimation and time-frequency signalanalysis problems. For these problems the negative frequency componentof real signals causes unwanted interference. The task of designing afilter to produce an approximation to the ideal analytic signal is notas simple as its formulation might suggest. Our result is that thedirect methods of zeroing the negative frequencies, or using Hilberttransform filters, have undesirable defects. We present an alternative which is similar to the quadrature filters used in modemdesigns},
    Journal = {Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on]},
    Keywords = {Analytic Signal, Hilbert Transform, filtering theory, frequency estimation, parameter estimation, signal processing, signal synthesis, time-frequency analysis, Hilbert transform filters, analytic signal generation, discrete analytic signal, discrete real-valued signal, instantaneous-frequency estimation, modem designs, negative frequencies, positive frequencies, quadrature filters, time-frequency signal analysis},
    Owner = {ofrey},
    Pdf = {../../../docs/reillyFrazerBoashash94.pdf} 
    }
    


  15. Sasan S. Saatchi, D. M. Le Vine, and R. H. Lang. Microwave backscattering and emission model for grass canopies. IEEE Trans. Geosci. Remote Sens., 32(1):177-186, January 1994. Keyword(s): atmospheric techniques, atmospheric temperature, geophysical techniques, hydrological techniques, radiometry, remote sensing, remote sensing by radar, soil, temperature measurement, 1.4 GHz, 4.75 GHz, C-band, L-band, UHF SHF, distorted Born approximation, elliptical disc, emission model, emissivity, geophysical measurement technique, grass canopies, grassland, hydrology, land surface, microwave backscattering, model, radar cross section, radar remote sensing, soil moisture, thatch layer, vegetation, vegetation canopy, wet Konza prairie, Backscatter, Electromagnetic heating, L-band, Microwave measurements, Microwave radiometry, Moisture measurement, Radar cross section, Radar measurements, Soil measurements, Soil moisture.
    Abstract: Microwave radar and radiometer measurements of grasslands indicate a substantial reduction in sensor sensitivity to soil moisture in the presence of a thatch layer. When this layer is wet it masks changes in the underlying soil, making the canopy appear warm in the case of passive sensors (radiometer) and decreasing backscatter in the active case (scatterometer). A model for a grass canopy with thatch is presented in order to explain this behavior and for comparison with observations. The canopy model consists of three layers: grass, thatch, and the underlying soil. The grass blades are modeled by elongated elliptical discs and the thatch is modeled as a collection of disk shaped water droplets (i.e., the dry matter is neglected). The ground is homogeneous and flat. The distorted Born approximation is used to compute the radar cross section of this three layer canopy and the emissivity is computed from the radar cross section using the Peake formulation for the passive problem. Results are computed at L-band (1.4 GHz) and C-band (4.75 GHz) using canopy parameters (i.e., plant geometry, soil moisture, plant moisture, etc.) representative of Konza Prairie grasslands. The results are compared to C-band scatterometer measurements and L-band radiometer measurements at these grasslands

    @Article{saatchiLeVineLangTGRS1994,
    author = {Sasan S. Saatchi and D. M. Le Vine and R. H. Lang},
    title = {Microwave backscattering and emission model for grass canopies},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {1994},
    volume = {32},
    number = {1},
    month = jan,
    pages = {177-186},
    issn = {0196-2892},
    doi = {10.1109/36.285200},
    abstract = {Microwave radar and radiometer measurements of grasslands indicate a substantial reduction in sensor sensitivity to soil moisture in the presence of a thatch layer. When this layer is wet it masks changes in the underlying soil, making the canopy appear warm in the case of passive sensors (radiometer) and decreasing backscatter in the active case (scatterometer). A model for a grass canopy with thatch is presented in order to explain this behavior and for comparison with observations. The canopy model consists of three layers: grass, thatch, and the underlying soil. The grass blades are modeled by elongated elliptical discs and the thatch is modeled as a collection of disk shaped water droplets (i.e., the dry matter is neglected). The ground is homogeneous and flat. The distorted Born approximation is used to compute the radar cross section of this three layer canopy and the emissivity is computed from the radar cross section using the Peake formulation for the passive problem. Results are computed at L-band (1.4 GHz) and C-band (4.75 GHz) using canopy parameters (i.e., plant geometry, soil moisture, plant moisture, etc.) representative of Konza Prairie grasslands. The results are compared to C-band scatterometer measurements and L-band radiometer measurements at these grasslands},
    keywords = {atmospheric techniques;atmospheric temperature;geophysical techniques;hydrological techniques;radiometry;remote sensing;remote sensing by radar;soil;temperature measurement;1.4 GHz;4.75 GHz;C-band;L-band;UHF SHF;distorted Born approximation;elliptical disc;emission model;emissivity;geophysical measurement technique;grass canopies;grassland;hydrology;land surface;microwave backscattering;model;radar cross section;radar remote sensing;soil moisture;thatch layer;vegetation;vegetation canopy;wet Konza prairie;Backscatter;Electromagnetic heating;L-band;Microwave measurements;Microwave radiometry;Moisture measurement;Radar cross section;Radar measurements;Soil measurements;Soil moisture},
    owner = {ofrey},
    
    }
    


  16. D.E. Wahl, P.H. Eichel, D.C. Ghiglia, and C.V. Jakowatz. Phase gradient autofocus-a robust tool for high resolution SAR phase correction. IEEE Transactions on Aerospace and Electronic Systems, 30(3):827-835, July 1994. Keyword(s): SAR Processing, Autofocus, Phase Gradient Autofocus.
    Abstract: The phase gradient autofocus (PGA) technique for phase error correction of spotlight mde synthetic aperture radar (SAR) imagery is examined carefully in the context of four fundamental signal processing steps that constitute the algorithm We demnstrate that excellent results over a wide variety of scene content, and phase error function structure are obtained if and only if all of these steps are included in the processing. Finally, we show that the computational demands of the full PGA algorithm do not represent a large fraction of the total image formation problem, when mid to large size images are involved.

    @Article{wahlEichelGhigliaJakowatz94,
    author = {Wahl, D.E. and Eichel, P.H. and Ghiglia, D.C. and Jakowatz, C.V.},
    journal = {IEEE Transactions on Aerospace and Electronic Systems},
    title = {Phase gradient autofocus-a robust tool for high resolution {SAR} phase correction},
    year = {1994},
    month = jul,
    number = {3},
    pages = {827--835},
    volume = {30},
    abstract = {The phase gradient autofocus (PGA) technique for phase error correction of spotlight mde synthetic aperture radar (SAR) imagery is examined carefully in the context of four fundamental signal processing steps that constitute the algorithm We demnstrate that excellent results over a wide variety of scene content, and phase error function structure are obtained if and only if all of these steps are included in the processing. Finally, we show that the computational demands of the full PGA algorithm do not represent a large fraction of the total image formation problem, when mid to large size images are involved.},
    file = {:wahlEichelGhigliaJakowatz94.pdf:PDF},
    keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus},
    owner = {ofrey},
    pdf = {../../../docs/wahlEichelGhigliaJakowatz94.pdf},
    
    }
    


  17. Howard A. Zebker, Paul A. Rosen, Richard M. Goldstein, Andrew Gabriel, and Charles L. Werner. On the derivation of coseismic displacement fields using differential radar interferometry: The Landers earthquake. Journal of Geophysical Research: Solid Earth, 99(B10):19617-19634, 1994. Keyword(s): SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Earthquake, Landers earthquake, Fault Slip, Remote sensing, Seismic instruments and networks, Earthquake source observations, Earthquake interaction, forecasting, and prediction.
    Abstract: We present a map of the coseismic displacement field resulting from the Landers, California, June 28, 1992, earthquake derived using data acquired from an orbiting high-resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS 1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high-resolution, wide area map of the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m resolution element in a 113 km by 90 km image. Our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of these data with Global Positioning System and electronic distance measurement survey data yield a correlation of 0.96; thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous similar applications of differential radar interferometry. Since we require only remotely sensed satellite data with no additional requirements for ancillary information, the technique is well suited for global seismic monitoring and analysis.

    @Article{zebkerRosenGoldsteinGabrielWernerJGR1994DInSARLandersEQuakeCoseismicDisplacement,
    author = {Zebker, Howard A. and Rosen, Paul A. and Goldstein, Richard M. and Gabriel, Andrew and Werner, Charles L.},
    journal = {Journal of Geophysical Research: Solid Earth},
    title = {On the derivation of coseismic displacement fields using differential radar interferometry: The {Landers} earthquake},
    year = {1994},
    issn = {2156-2202},
    number = {B10},
    pages = {19617-19634},
    volume = {99},
    abstract = {We present a map of the coseismic displacement field resulting from the Landers, California, June 28, 1992, earthquake derived using data acquired from an orbiting high-resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS 1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high-resolution, wide area map of the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m resolution element in a 113 km by 90 km image. Our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of these data with Global Positioning System and electronic distance measurement survey data yield a correlation of 0.96; thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous similar applications of differential radar interferometry. Since we require only remotely sensed satellite data with no additional requirements for ancillary information, the technique is well suited for global seismic monitoring and analysis.},
    doi = {10.1029/94JB01179},
    file = {:zebkerRosenGoldsteinGabrielWernerJGR1994DInSARLandersEQuakeCoseismicDisplacement.pdf:PDF},
    keywords = {SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Deformation Mapping, Deformation Monitoring, ERS-1, Displacement, Surface Displacement, Surface Deformation, Spaceborne SAR, C-band, Earthquake, Landers earthquake, Fault Slip,Remote sensing, Seismic instruments and networks, Earthquake source observations, Earthquake interaction, forecasting, and prediction},
    owner = {ofrey},
    pdf = {../../../docs/zebkerRosenGoldsteinGabrielWernerJGR1994DInSARLandersEQuakeCoseismicDisplacement.pdf},
    url = {http://dx.doi.org/10.1029/94JB01179},
    
    }
    


Conference articles

  1. Matthew Braunstein, James M. Ralston, and David A. Sparrow. Signal processing approaches to radio frequency interference (RFI) suppression. In Dominick A. Giglio, editor, Algorithms for Synthetic Aperture Radar Imagery, volume 2230, pages 190-208, 1994. SPIE. Keyword(s): SAR Processing, RFI Suppression, Ultra-Wideband SAR, Airborne SAR.
    Abstract: Ultra-wideband radar (UWB) has been shown to be among the most powerful techniques available for underground and obscured object detection. The value of such systems is that they combine the penetration enhancement associated with VHF/UHF (and lower) frequencies with the resolution of wide absolute bandwidth. Such systems necessarily make use of much of the frequency spectrum already in heavy use by other services, such as television and mobile communications. Although this spectral overlap provides occasion for adverse consequences in both directions, to date the principal consequence has been often-severe impact on UWB radar measurements. Even in remote locations, the average interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity. Nor are UWB radar designers free to overcome this interference by increasing radar power, since regulatory sanction for UWB operation will depend on maintaining sufficiently low spectral power densities to assure that other, prior, services are not appreciably degraded. Given the importance of radio frequency interference (RFI) on practical ultrawide band ground penetrating radar systems, it is important to consider how and to what extent the effects of RFI noise may be reduced. The overall problem of RFI and its impacts will be described and several signal processing approaches to removal of RFI will be discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches, which have been developed and applied by the signal processing community in other contexts. These methods will be applied to several different real-world experimental data sets, and quantitative measures of the effectiveness of each of these algorithms in removing RFI noise will be presented. Although computationally-intensive, most of the techniques to be described achieve substantial increases in S/RFI without requiring concomitant increases in radar average power.

    @InProceedings{braunsteinRalstonSparrow94:RFI,
    Title = {{Signal processing approaches to radio frequency interference (RFI) suppression}},
    Author = {Matthew Braunstein and James M. Ralston and David A. Sparrow},
    Booktitle = {Algorithms for Synthetic Aperture Radar Imagery},
    Editor = {Dominick A. Giglio},
    Location = {Orlando, FL, USA},
    Number = {1},
    Pages = {190--208},
    Publisher = {SPIE},
    Url = {http://link.aip.org/link/?PSI/2230/190/1},
    Volume = {2230},
    Year = {1994},
    Abstract = {Ultra-wideband radar (UWB) has been shown to be among the most powerful techniques available for underground and obscured object detection. The value of such systems is that they combine the penetration enhancement associated with VHF/UHF (and lower) frequencies with the resolution of wide absolute bandwidth. Such systems necessarily make use of much of the frequency spectrum already in heavy use by other services, such as television and mobile communications. Although this spectral overlap provides occasion for adverse consequences in both directions, to date the principal consequence has been often-severe impact on UWB radar measurements. Even in remote locations, the average interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity. Nor are UWB radar designers free to overcome this interference by increasing radar power, since regulatory sanction for UWB operation will depend on maintaining sufficiently low spectral power densities to assure that other, prior, services are not appreciably degraded. Given the importance of radio frequency interference (RFI) on practical ultrawide band ground penetrating radar systems, it is important to consider how and to what extent the effects of RFI noise may be reduced. The overall problem of RFI and its impacts will be described and several signal processing approaches to removal of RFI will be discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches, which have been developed and applied by the signal processing community in other contexts. These methods will be applied to several different real-world experimental data sets, and quantitative measures of the effectiveness of each of these algorithms in removing RFI noise will be presented. Although computationally-intensive, most of the techniques to be described achieve substantial increases in S/RFI without requiring concomitant increases in radar average power.},
    Keywords = {SAR Processing, RFI Suppression, Ultra-Wideband SAR, Airborne SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/braunsteinRalstonSparrow94.pdf} 
    }
    


  2. Charles V. Jakowatz, Daniel E. Wahl, Paul H. Eichel, and Paul A. Thompson. New formulation for interferometric synthetic aperture radar for terrain mapping. In Dominick A. Giglio, editor, , volume 2230, pages 411-418, 1994. SPIE. Keyword(s): SAR Processing, InSAR, SAR Interferometry, Terrain Mapping, Topography, Spotlight SAR, Spotlight-mode data.
    @Conference{jakowatzWahlEichelThompsonInSAR1994,
    author = {Charles V. Jakowatz and Daniel E. Wahl and Paul H. Eichel and Paul A. Thompson},
    title = {New formulation for interferometric synthetic aperture radar for terrain mapping},
    year = {1994},
    editor = {Dominick A. Giglio},
    volume = {2230},
    number = {1},
    pages = {411-418},
    publisher = {SPIE},
    doi = {10.1117/12.177193},
    file = {:jakowatzWahlEichelThompsonInSAR1994.pdf:PDF},
    journal = {Algorithms for Synthetic Aperture Radar Imagery},
    keywords = {SAR Processing, InSAR, SAR Interferometry, Terrain Mapping, Topography, Spotlight SAR, Spotlight-mode data},
    location = {Orlando, FL, USA},
    owner = {ofrey},
    pdf = {../../../docs/jakowatzWahlEichelThompsonInSAR1994.pdf},
    url = {http://link.aip.org/link/?PSI/2230/411/1},
    
    }
    


  3. Alberto Moreira and Rolf Scheiber. Doppler parameter estimation algorithms for SAR processing with the chirp scaling approach. In Geoscience and Remote Sensing Symposium, 1994. IGARSS '94. 'Surface and Atmospheric Remote Sensing: Technologies, Data Analysis and Interpretation'., International, volume 4, pages 1977-1979, 1994. Keyword(s): SAR Processing, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, SDE, CDE, Sign Doppler Estimator, Correlation Doppler Estimator, Doppler radar, FM radar, airborne radar, geophysical signal processing, geophysical techniques, radar applications, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, Doppler parameter estimation algorithm, Doppler parameters, Doppler rate, SAC, SAR imaging, SAR processing, SPECAN, airborne radar, autocorrelation function, Chirp Scaling Algorithm, chirp scaling approach, correlation method, geophysical measurement technique, image processing, land surface, range-frequency centroid, remote sensing, shift and correlate algorithm, signal processing, spaceborne SAR, synthetic aperture radar, terrain mapping.
    Abstract: This paper presents several correlation based methods for estimation of the Doppler parameters from SAR raw data in connection with the chirp scaling algorithm. For the estimation of the Doppler rate, a modified approach of the shift and correlate (SAC) algorithm is proposed. In this case, the auto-correlation function of each data set and the standard deviation of the velocity calculations are used in order to monitor the validity of the estimations. For resolving the PRF ambiguity, a new approach is proposed, which is based on the estimation of the range-frequency centroid as a function of the azimuth frequency. Several results of the Doppler parameters estimation are presented for airborne and spaceborne SAR data

    @InProceedings{moreiraScheiber94:DopplerParam,
    Title = {Doppler parameter estimation algorithms for SAR processing with the chirp scaling approach},
    Author = {Moreira, Alberto and Scheiber, Rolf},
    Booktitle = {Geoscience and Remote Sensing Symposium, 1994. IGARSS '94. 'Surface and Atmospheric Remote Sensing: Technologies, Data Analysis and Interpretation'., International},
    Pages = {1977--1979},
    Url = {http://ieeexplore.ieee.org/iel2/3183/9018/00399628.pdf},
    Volume = {4},
    Year = {1994},
    Abstract = {This paper presents several correlation based methods for estimation of the Doppler parameters from SAR raw data in connection with the chirp scaling algorithm. For the estimation of the Doppler rate, a modified approach of the shift and correlate (SAC) algorithm is proposed. In this case, the auto-correlation function of each data set and the standard deviation of the velocity calculations are used in order to monitor the validity of the estimations. For resolving the PRF ambiguity, a new approach is proposed, which is based on the estimation of the range-frequency centroid as a function of the azimuth frequency. Several results of the Doppler parameters estimation are presented for airborne and spaceborne SAR data},
    Keywords = {SAR Processing, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, SDE, CDE, Sign Doppler Estimator, Correlation Doppler Estimator, Doppler radar, FM radar, airborne radar, geophysical signal processing, geophysical techniques, radar applications, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, Doppler parameter estimation algorithm, Doppler parameters, Doppler rate, SAC, SAR imaging, SAR processing, SPECAN, airborne radar, autocorrelation function, Chirp Scaling Algorithm, chirp scaling approach, correlation method, geophysical measurement technique, image processing, land surface, range-frequency centroid, remote sensing, shift and correlate algorithm, signal processing, spaceborne SAR, synthetic aperture radar, terrain mapping},
    Owner = {ofrey},
    Pdf = {../../../docs/moreiraScheiber94.pdf} 
    }
    


  4. Rolf Scheiber and Alberto Moreira. Extension of the Correlation Doppler Estimator for Determination of the Doppler Rate and for Resolving the PRF-Ambiguity. In Giorgio Franceschetti, editor, SAR Data Processing for Remote Sensing, volume SPIE 2316, pages 33-41, 1994. Keyword(s): SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Correlation Doppler Estimator, CDE, Sign Doppler Estimator, SDE, Doppler Ambiguity Resolver, DAR, Doppler Rate Estimation, Autofocus.
    Abstract: Recently the chirp scaling algorithm has been proposed for high quality SAR processing. The algorithm requires first a transformation of the range uncompressed SAR raw data into the range-Doppler domain, which does not permit conventional techniques for the estimation of the Doppler parameters to be introduced efficiently into the processing. This paper first reviews the so called 'correlation Doppler estimator' (CDE), which was proposed for the estimation of the Doppler centroid in the time domain. This estimation algorithm is further extended in order to allow also the estimation of the Doppler rate. To perform this only bright targets are considered. By continuous calculation of the first coefficient of the auto-correlation function, the slope of the frequency history of the Doppler signal is determined, giving an exact estimate of the Doppler rate. to obtain also an estimation of the Doppler rate for scenes without bright targets but with some contrast, a modified version of the SAC algorithm is presented. Further a new method is presented, which can solve the PRF-ambiguity by means of an evaluation of the signal envelope skew in the range-Doppler domain. This technique does not require any additional range FFT, since it is based on the estimation of the variation of a range centroid as a function of the azimuth frequency. Several results are presented, which show the performance of the proposed new approaches. Some remarks are made regarding the inclusion of the described methods into the extended chirp scaling algorithm.

    @InProceedings{scheiberMoreira94:DopCentrEst,
    Title = {{Extension of the Correlation Doppler Estimator for Determination of the Doppler Rate and for Resolving the PRF-Ambiguity}},
    Author = {Rolf Scheiber and Alberto Moreira},
    Booktitle = {SAR Data Processing for Remote Sensing},
    Editor = {Giorgio Franceschetti},
    Pages = {33-41},
    Url = {http://spie.org/scripts/abstract.pl?bibcode=1994SPIE%2e2316%2e%2e%2e33S&page=1&qs=spie},
    Volume = {SPIE 2316},
    Year = {1994},
    Abstract = {Recently the chirp scaling algorithm has been proposed for high quality SAR processing. The algorithm requires first a transformation of the range uncompressed SAR raw data into the range-Doppler domain, which does not permit conventional techniques for the estimation of the Doppler parameters to be introduced efficiently into the processing. This paper first reviews the so called 'correlation Doppler estimator' (CDE), which was proposed for the estimation of the Doppler centroid in the time domain. This estimation algorithm is further extended in order to allow also the estimation of the Doppler rate. To perform this only bright targets are considered. By continuous calculation of the first coefficient of the auto-correlation function, the slope of the frequency history of the Doppler signal is determined, giving an exact estimate of the Doppler rate. to obtain also an estimation of the Doppler rate for scenes without bright targets but with some contrast, a modified version of the SAC algorithm is presented. Further a new method is presented, which can solve the PRF-ambiguity by means of an evaluation of the signal envelope skew in the range-Doppler domain. This technique does not require any additional range FFT, since it is based on the estimation of the variation of a range centroid as a function of the azimuth frequency. Several results are presented, which show the performance of the proposed new approaches. Some remarks are made regarding the inclusion of the described methods into the extended chirp scaling algorithm.},
    Keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, Correlation Doppler Estimator, CDE, Sign Doppler Estimator, SDE, Doppler Ambiguity Resolver, DAR, Doppler Rate Estimation, Autofocus},
    Pdf = {../../../docs/scheiber94.pdf} 
    }
    


  5. D.E. Wahl, C.V. Jakowatz, and P.A. Thompson. New approach to strip-map SAR autofocus. In Digital Signal Processing Workshop, 1994., 1994 Sixth IEEE, pages 53-56, October 1994. Keyword(s): SAR Processing, Autofocus, Phase Curvature Autofocus, Phase Gradient Autofocus.
    Abstract: This paper demonstrates how certain concepts from the Phase Gradient Autofocus (PGA) algorithm for automated refocus of spotlight mode SAR imagery may be used to design a similar algorithm that applies to SAR imagery formed in the conventional strip-mapping mode. The algorithm derivation begins with the traditional view of strip-map image formation as convolution (compression) using a linear FM chirp sequence. The appropriate analogies and modifications to the spotlight mode case are used to describe a working algorithm for strip-map autofocus.

    @InProceedings{wahlJakowatzThompson1994:PhaseCurvatureAutofocus,
    Title = {New approach to strip-map SAR autofocus},
    Author = {Wahl, D.E. and Jakowatz, C.V. and Thompson, P.A.},
    Booktitle = {Digital Signal Processing Workshop, 1994., 1994 Sixth IEEE},
    Month = oct,
    Pages = {53--56},
    Url = {http://ieeexplore.ieee.org/iel2/3037/8630/00379875.pdf},
    Year = {1994},
    Abstract = {This paper demonstrates how certain concepts from the Phase Gradient Autofocus (PGA) algorithm for automated refocus of spotlight mode SAR imagery may be used to design a similar algorithm that applies to SAR imagery formed in the conventional strip-mapping mode. The algorithm derivation begins with the traditional view of strip-map image formation as convolution (compression) using a linear FM chirp sequence. The appropriate analogies and modifications to the spotlight mode case are used to describe a working algorithm for strip-map autofocus.},
    Keywords = {SAR Processing, Autofocus, Phase Curvature Autofocus, Phase Gradient Autofocus},
    Owner = {ofrey},
    Pdf = {../../../docs/wahlJakowatzThompson1994.pdf} 
    }
    


Internal reports

  1. Kenneth Knaell. Three-Dimensional SAR from Curvilinear Apertures. Technical report, Carerock Division, Naval Surface Warfare Center, 1994. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, 3D Feature Extraction, Target Feature Extraction, Curvilinear SAR.
    @TechReport{knaellReport1994:NonLinearSARTomo,
    Title = {Three-Dimensional SAR from Curvilinear Apertures},
    Author = {Knaell, Kenneth},
    Institution = {Carerock Division, Naval Surface Warfare Center},
    Year = {1994},
    Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, 3D Feature Extraction, Target Feature Extraction, Curvilinear SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/knaellReport1994.pdf},
    Timestamp = {2007.11.06} 
    }
    


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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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