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Publications of year 1996
Books and proceedings

Charles V. Jakowatz,
Daniel E. Wahl,
Paul H. Eichel,
Dennis C. Ghiglia,
and Paul A. Thompson.
SpotlightMode Synthetic Aperture Radar: A Signal Processing Approach.
Norwell, MA: Kluwer Academic Publishers,
1996.
Keyword(s): SAR Processing,
Spotlight SAR,
Spotlight mode,
Autofocus,
Phase Gradient Autofocus,
PGA,
Motion Compensation,
MoComp,
Airborne SAR,
SAR Tomography,
Tomography,
InSAR,
SAR Interferometry.
@Book{jakowatzWahlEichelGhigliaThompson1996:BookSpotlightSAR,
Title = {SpotlightMode Synthetic Aperture Radar: A Signal Processing Approach},
Author = {Charles V. Jakowatz and Daniel E. Wahl and Paul H. Eichel and Dennis C. Ghiglia and Paul A. Thompson},
Publisher = {Norwell, MA: Kluwer Academic Publishers},
Year = {1996},
Keywords = {SAR Processing, Spotlight SAR, Spotlight mode, Autofocus, Phase Gradient Autofocus, PGA, Motion Compensation, MoComp,Airborne SAR, SAR Tomography, Tomography, InSAR, SAR Interferometry},
Owner = {ofrey}
}
Thesis

David W. Hawkins.
Synthetic aperture imaging algorithms : with application to wide bandwidth sonar.
PhD thesis,
University of Canterbury. Electrical and Computer Engineering,
1996.
Keyword(s): SAR Processing,
Azimuth Focusing,
Autofocus,
Synthetic Aperture Sonar,
SAS,
Sonar,
Phase Gradient Autofocus,
Stripmap,
rangeDoppler Algorithm,
Chirp Scaling Algorithm,
CSA,
omegak,
Wavenumber Domain Algorithm.
Abstract: 
This thesis contains the complete endtoend simulation, development, implementation, and calibration of the wide bandwidth, lowQ, KiwiSAS synthetic aperture sonar (SAS). Through the use of a very stable towfish, a new novel wide bandwidth transducer design, and autofocus procedures, highresolution diffraction limited imagery is produced. As a complete system calibration was performed, this diffraction limited imagery is not only geometrically calibrated, it is also calibrated for target crosssection or target strength estimation. Is is important to note that the diffraction limited images are formed without access to any form of inertial measurement information. Previous investigations applying the synthetic aperture technique to sonar have developed processors based on exact, but inefficient, spatialtemporal domain timedelay and sum beamforming algorithms, or they have performed equivalent operations in the frequency domain using fastcorrelation techniques (via the fast Fourier transform (FFT)). In this thesis, the algorithms used in the generation of synthetic aperture radar (SAR) images are derived in their wide bandwidth forms and it is shown that these more efficient algorithms can be used to form diffraction limited SAS images. Several new algorithms are developed; accelerated chirp scaling algorithm represents an efficient method for processing synthetic aperture data, while modified phase gradient autofocus and a lowQ autofocus routine based on prominent point processing are used to focus both simulated and real target data that has been corrupted by known and unknown motion or medium propagation errors. 
@PhdThesis{hawkinsPhDThesis1996,
author = {David W. Hawkins},
title = {Synthetic aperture imaging algorithms : with application to wide bandwidth sonar},
school = {University of Canterbury. Electrical and Computer Engineering},
year = {1996},
abstract = {This thesis contains the complete endtoend simulation, development, implementation, and calibration of the wide bandwidth, lowQ, KiwiSAS synthetic aperture sonar (SAS). Through the use of a very stable towfish, a new novel wide bandwidth transducer design, and autofocus procedures, highresolution diffraction limited imagery is produced. As a complete system calibration was performed, this diffraction limited imagery is not only geometrically calibrated, it is also calibrated for target crosssection or target strength estimation. Is is important to note that the diffraction limited images are formed without access to any form of inertial measurement information. Previous investigations applying the synthetic aperture technique to sonar have developed processors based on exact, but inefficient, spatialtemporal domain timedelay and sum beamforming algorithms, or they have performed equivalent operations in the frequency domain using fastcorrelation techniques (via the fast Fourier transform (FFT)). In this thesis, the algorithms used in the generation of synthetic aperture radar (SAR) images are derived in their wide bandwidth forms and it is shown that these more efficient algorithms can be used to form diffraction limited SAS images. Several new algorithms are developed; accelerated chirp scaling algorithm represents an efficient method for processing synthetic aperture data, while modified phase gradient autofocus and a lowQ autofocus routine based on prominent point processing are used to focus both simulated and real target data that has been corrupted by known and unknown motion or medium propagation errors.},
file = {:hawkinsPhDThesis1996.pdf:PDF},
keywords = {SAR Processing, Azimuth Focusing, Autofocus, Synthetic Aperture Sonar, SAS, Sonar, Phase Gradient Autofocus, Stripmap, rangeDoppler Algorithm, Chirp Scaling Algorithm, CSA, omegak, Wavenumber Domain Algorithm},
owner = {ofrey},
pdf = {../../../docs/hawkinsPhDThesis1996.pdf},
url = {http://hdl.handle.net/10092/1082},
}
Articles in journal or book chapters

Regine Bolter,
Margrit Gelautz,
and Franz Leberl.
SAR Speckle Simulation.
International Archives of Photogrammetry and Remote Sensing,
21:2025,
1996.
Keyword(s): SAR Processing,
Simulation,
Speckle,
Speckle Simulation.
Abstract: 
After a short introduction to the principles of SAR speckle generation and its statistical properties, we give a review of different speckle simulation methods described in literature. Then, the implementation of some selected algorithms is described, and their performance is tested on simulated ERS1 images. Special attention is paid to the modeling of multiple looks, and the differences between image pixel size and original radar ground resolution. A chisquare distribution and a Rayleigh distribution with multiple file averaging were found to produce the most realistic results. 
@Article{BoltGelaLeb96:specklesim,
Title = {{SAR Speckle Simulation}},
Author = {Regine Bolter and Margrit Gelautz and Franz Leberl},
Pages = {2025},
Url = {http://www.icg.tugraz.ac.at/bolter96/isprs96.pdf},
Volume = {21},
Year = {1996},
Abstract = {After a short introduction to the principles of SAR speckle generation and its statistical properties, we give a review of different speckle simulation methods described in literature. Then, the implementation of some selected algorithms is described, and their performance is tested on simulated ERS1 images. Special attention is paid to the modeling of multiple looks, and the differences between image pixel size and original radar ground resolution. A chisquare distribution and a Rayleigh distribution with multiple file averaging were found to produce the most realistic results.},
Journal = {International Archives of Photogrammetry and Remote Sensing},
Keywords = {SAR Processing, Simulation, Speckle, Speckle Simulation},
Pdf = {../../../docs/BoltGelaLLeberl96.pdf}
}

Shane R. Cloude and Eric Pottier.
A review of target decomposition theorems in radar polarimetry.
IEEE Transactions on Geoscience and Remote Sensing,
34(2):498518,
March 1996.
Keyword(s): Smatrix theory,
backscatter,
covariance matrices,
eigenvalues and eigenfunctions,
geophysical signal processing,
matrix decomposition,
radar crosssections,
radar imaging,
radar polarimetry,
remote sensing by radar,
reviews,
Mueller matrix,
Stokes vector,
backscatter,
coherency matrix,
coherent decomposition,
covariance matrix,
eigenvector analysis,
radar polarimetry,
scattering matrix,
target decomposition theorems,
terrain,
transformation theory.
Abstract: 
In this paper, we provide a review of the different approaches used for target decomposition theory in radar polarimetry. We classify three main types of theorem; those based on the Mueller matrix and Stokes vector, those using an eigenvector analysis of the covariance or coherency matrix, and those employing coherent decomposition of the scattering matrix. We unify the formulation of these different approaches using transformation theory and an eigenvector analysis. We show how special forms of these decompositions apply for the important case of backscatter from terrain with generic symmetries 
@Article{cloudePottier1996:ReviewOfPolSARDecomp,
Title = {A review of target decomposition theorems in radar polarimetry},
Author = {Cloude, Shane R. and Pottier, Eric},
Doi = {10.1109/36.485127},
ISSN = {01962892},
Month = mar,
Number = {2},
Pages = {498518},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=485127&isnumber=10355},
Volume = {34},
Year = {1996},
Abstract = {In this paper, we provide a review of the different approaches used for target decomposition theory in radar polarimetry. We classify three main types of theorem; those based on the Mueller matrix and Stokes vector, those using an eigenvector analysis of the covariance or coherency matrix, and those employing coherent decomposition of the scattering matrix. We unify the formulation of these different approaches using transformation theory and an eigenvector analysis. We show how special forms of these decompositions apply for the important case of backscatter from terrain with generic symmetries},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {Smatrix theory, backscatter, covariance matrices, eigenvalues and eigenfunctions, geophysical signal processing, matrix decomposition, radar crosssections, radar imaging, radar polarimetry, remote sensing by radar, reviews, Mueller matrix, Stokes vector, backscatter, coherency matrix, coherent decomposition, covariance matrix, eigenvector analysis, radar polarimetry, scattering matrix, target decomposition theorems, terrain, transformation theory},
Owner = {ofrey},
Pdf = {../../../docs/cloudePottier1996.pdf}
}

G.W. Davidson,
Ian G. Cumming,
and M.R. Ito.
A chirp scaling approach for processing squint mode SAR data.
IEEE_J_AES,
32(1):121133,
January 1996.
Keyword(s): SAR Processing,
Cband,
Lband,
chirp scaling algorithm,
image degradations,
image formation,
nonlinear FM chirp scaling,
phase modulation,
rangevariant filtering,
resolution width,
secondary range compression,
sidelobe level,
squint mode SAR data,
FM radar,
data compression,
filtering theory,
image resolution,
phase modulation,
radar imaging,
synthetic aperture radar.
Abstract: 
Image formation from squint mode synthetic aperture radar (SAR) is limited by image degradations caused by neglecting the rangevariant filtering required by secondary range compression (SRC). Introduced here is a nonlinear FM chirp scaling, an extension of the chirp scaling algorithm, as an efficient and accurate approach to range variant SRC. Two methods of implementing the approach are described. The nonlinear FM filtering method is more accurate but adds a filtering step to the chirp scaling algorithm, although the extra computation is less than that of a time domain residual compression filter. The nonlinear FM pulse method consists of changing the phase modulation of the transmitted pulse, thus avoiding an increase in computation. Simulations show both methods significantly improve resolution width and sidelobe level, compared with existing SAR processors for squint angles above 10 deg for Lband and 20 deg for Cband. 
@Article{DavidsonCummingIto1996:ChirpScalingForHigherSquint,
Title = {A chirp scaling approach for processing squint mode {SAR} data},
Author = {Davidson, G.W. and Cumming, Ian G. and Ito, M.R.},
Doi = {10.1109/7.481254},
ISSN = {00189251},
Month = jan,
Number = {1},
Pages = {121133},
Volume = {32},
Year = {1996},
Abstract = {Image formation from squint mode synthetic aperture radar (SAR) is limited by image degradations caused by neglecting the rangevariant filtering required by secondary range compression (SRC). Introduced here is a nonlinear FM chirp scaling, an extension of the chirp scaling algorithm, as an efficient and accurate approach to range variant SRC. Two methods of implementing the approach are described. The nonlinear FM filtering method is more accurate but adds a filtering step to the chirp scaling algorithm, although the extra computation is less than that of a time domain residual compression filter. The nonlinear FM pulse method consists of changing the phase modulation of the transmitted pulse, thus avoiding an increase in computation. Simulations show both methods significantly improve resolution width and sidelobe level, compared with existing SAR processors for squint angles above 10 deg for Lband and 20 deg for Cband.},
Journal = IEEE_J_AES,
Keywords = {SAR Processing, Cband;Lband;chirp scaling algorithm;image degradations;image formation;nonlinear FM chirp scaling;phase modulation;rangevariant filtering;resolution width;secondary range compression;sidelobe level;squint mode SAR data;FM radar;data compression;filtering theory;image resolution;phase modulation;radar imaging;synthetic aperture radar}
}

G. Fornaro,
G. Franceschetti,
and R. Lanari.
Interferometric SAR phase unwrapping using Green's formulation.
IEEE Transactions on Geoscience and Remote Sensing,
34(3):720 727,
May 1996.
Keyword(s): SAR Processing,
InSAR,
SAR Interferometry,
Phase Unwrapping,
Green's first identity,
Green's formulation,
ISAR,
SAR,
algorithm,
geodesy,
geophysical measurement technique,
interferometric SAR phase unwrapping,
land surface topography,
radar imaging,
synthetic aperture radar,
terrain mapping,
unwrapped phase value,
geophysical techniques,
radar imaging,
radiowave interferometry,
remote sensing by radar,
synthetic aperture radar,
topography (Earth).
Abstract: 
Any method that permits retrieving full range (unwrapped) phase values starting from their ( pi;, pi;) determination (wrapped phase) can be defined as a phase unwrapping technique. This paper addresses a new procedure for phase unwrapping especially designed for interferometric synthetic aperture radar applications. The proposed algorithm is based on use of Green's first identity. Results on simulated as well as on real data are presented. They both confirm the excellent performance of the procedure 
@Article{499751,
Title = {Interferometric SAR phase unwrapping using Green's formulation},
Author = {Fornaro, G. and Franceschetti, G. and Lanari, R.},
Doi = {10.1109/36.499751},
ISSN = {01962892},
Month = may,
Number = {3},
Pages = {720 727},
Volume = {34},
Year = {1996},
Abstract = {Any method that permits retrieving full range (unwrapped) phase values starting from their ( pi;, pi;) determination (wrapped phase) can be defined as a phase unwrapping technique. This paper addresses a new procedure for phase unwrapping especially designed for interferometric synthetic aperture radar applications. The proposed algorithm is based on use of Green's first identity. Results on simulated as well as on real data are presented. They both confirm the excellent performance of the procedure},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {SAR Processing, InSAR, SAR Interferometry, Phase Unwrapping, Green's first identity;Green's formulation;ISAR;SAR;algorithm;geodesy;geophysical measurement technique;interferometric SAR phase unwrapping;land surface topography;radar imaging;synthetic aperture radar;terrain mapping;unwrapped phase value;geophysical techniques;radar imaging;radiowave interferometry;remote sensing by radar;synthetic aperture radar;topography (Earth)}
}

Michael Y. Jin.
Optimal Range and Doppler Centroid Estimation for a ScanSAR System.
IEEE Transactions on Geoscience and Remote Sensing,
34(2):479488,
March 1996.
Keyword(s): SAR Processing,
Doppler Centroid,
Doppler Centroid Estimation,
Clutterlock,
ScanSAR,
SIRC,
ERS.
Abstract: 
This paper presents a new range and Doppler centroid estimation algorithm for a ScanSAR system. This algorithm is based on processing the image data in the overlapped region of two bursts of the same beam or adjacent beams. It leads to highly accurate radar pointing angles that are paramount to achieving good radiometric performance in ScanSAR imagery. The achievable accuracy is derived theoretically and verified by tests performed using SIRC ScanSAR data and ERS data. This algorithm is computationally efficient and easy to implement. The proposed Doppler centroid estimation algorithm is also an excellent candidate for a strip mode SAR system. 
@Article{Jin96:Doppler,
author = {Michael Y. Jin},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
title = {{Optimal Range and Doppler Centroid Estimation for a ScanSAR System}},
year = {1996},
month = mar,
number = {2},
pages = {479488},
volume = {34},
abstract = {This paper presents a new range and Doppler centroid estimation algorithm for a ScanSAR system. This algorithm is based on processing the image data in the overlapped region of two bursts of the same beam or adjacent beams. It leads to highly accurate radar pointing angles that are paramount to achieving good radiometric performance in ScanSAR imagery. The achievable accuracy is derived theoretically and verified by tests performed using SIRC ScanSAR data and ERS data. This algorithm is computationally efficient and easy to implement. The proposed Doppler centroid estimation algorithm is also an excellent candidate for a strip mode SAR system.},
keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Clutterlock, ScanSAR, SIRC, ERS},
pdf = {../../../docs/jin96.pdf},
}

Guoliang Jin and Dajun Tang.
Uncertainties of differential phase estimation associated with interferometric sonars.
Oceanic Engineering, IEEE Journal of,
21(1):53 63,
January 1996.
Keyword(s): Applied Physics Laboratory,
Benthic Acoustic Measurement System,
University of Washington,
baseline decorrelation,
depth measurement,
differential phase estimation,
differential phase technique,
equivalent noise source,
error,
excess deviation,
flat sandy bottom,
grazing angles,
instantaneous insonified area,
interferometric sonars,
interferometric system,
multiple bottom scatterers,
noise interference,
numerical simulations,
signalarrivalangle,
speckle phenomena,
uncertainties,
acoustic noise,
acoustic wave interferometry,
acoustic wave scattering,
bathymetry,
correlation theory,
digital simulation,
measurement errors,
phase estimation,
sonar;.
Abstract: 
The differential phase technique has been widely used in various sonar systems; however, uncertainties associated with the estimation of scatterer depths are not completely understood. Numerical simulations for multiple bottom scatterers are performed, and they show that the uncertainties of depth measurements, in the absence of noise interferences, are much greater than the amount explainable by the uncertainty associated with the signalarrivalangle within an instantaneous insonified area. The cause of the excess deviation is analyzed, particularly for the twoscatterer case. This kind of error is referred to as ldquo;baseline decorrelation rdquo; which is related to the speckle phenomena and can be considered as an equivalent noise source. Experimental data obtained by a particular highfrequency (40 kHz) interferometric system, the Benthic Acoustic Measurement System (BAMS) developed by the Applied Physics Laboratory, University of Washington, at a flat sandy bottom off the coast of Panama City, FL, were analyzed. Both analytical formulas and a numerical model are given to estimate the measurement uncertainty caused by the baseline decorrelation, as well as noise interferences based on the parameters of the BAMS, in order to understand uncertainties of the differential phase estimation. It is found that baseline decorrelation is the main source of error for the BAMS for grazing angles greater than 12 deg;. The measurement uncertainties at this grazing angle interval are in agreement with the theoretical predictions 
@Article{jinTang1996,
Title = {Uncertainties of differential phase estimation associated with interferometric sonars},
Author = {Guoliang Jin and Dajun Tang},
Doi = {10.1109/48.485201},
ISSN = {03649059},
Month = jan,
Number = {1},
Pages = {53 63},
Volume = {21},
Year = {1996},
Abstract = {The differential phase technique has been widely used in various sonar systems; however, uncertainties associated with the estimation of scatterer depths are not completely understood. Numerical simulations for multiple bottom scatterers are performed, and they show that the uncertainties of depth measurements, in the absence of noise interferences, are much greater than the amount explainable by the uncertainty associated with the signalarrivalangle within an instantaneous insonified area. The cause of the excess deviation is analyzed, particularly for the twoscatterer case. This kind of error is referred to as ldquo;baseline decorrelation rdquo; which is related to the speckle phenomena and can be considered as an equivalent noise source. Experimental data obtained by a particular highfrequency (40 kHz) interferometric system, the Benthic Acoustic Measurement System (BAMS) developed by the Applied Physics Laboratory, University of Washington, at a flat sandy bottom off the coast of Panama City, FL, were analyzed. Both analytical formulas and a numerical model are given to estimate the measurement uncertainty caused by the baseline decorrelation, as well as noise interferences based on the parameters of the BAMS, in order to understand uncertainties of the differential phase estimation. It is found that baseline decorrelation is the main source of error for the BAMS for grazing angles greater than 12 deg;. The measurement uncertainties at this grazing angle interval are in agreement with the theoretical predictions},
Journal = {Oceanic Engineering, IEEE Journal of},
Keywords = {Applied Physics Laboratory;Benthic Acoustic Measurement System;University of Washington;baseline decorrelation;depth measurement;differential phase estimation;differential phase technique;equivalent noise source;error;excess deviation;flat sandy bottom;grazing angles;instantaneous insonified area;interferometric sonars;interferometric system;multiple bottom scatterers;noise interference;numerical simulations;signalarrivalangle;speckle phenomena;uncertainties;acoustic noise;acoustic wave interferometry;acoustic wave scattering;bathymetry;correlation theory;digital simulation;measurement errors;phase estimation;sonar;}
}

R. Kwok and M.A. Fahnestock.
Ice sheet motion and topography from radar interferometry.
IEEE Trans. Geosci. Remote Sens.,
34(1):189200,
January 1996.
Keyword(s): SAR Processing,
Interferometry,
SAR interferometry,
differential SAR interferometry,
DInSAR,
Displacement,
Surface Displacement,
glaciology,
hydrological techniques,
radar applications,
radar imaging,
remote sensing by radar,
spaceborne radar,
synthetic aperture radar,
Greenland,
SAR method,
flow,
geophysical measurement technique,
glaciology,
hydrology,
ice sheet motion,
motion,
polar ice sheet,
radar interferometry,
radar remote sensing,
repeat pass ERS1 interferogram,
surface displacement field,
topography,
velocity field,
Data mining,
Ice surface,
Laboratories,
Propulsion,
Radar interferometry,
Satellites,
Space technology,
Streaming media,
Surface topography,
Synthetic aperture radar.
Abstract: 
Both topography and motion information are present in repeat pass ERS1 interferograms over ice sheets. The authors demonstrate that the topography is separable from the surface displacement field when a sequence of radar images are available. If the velocity field is constant over the time span of observation, the topography can be derived from differential interferograms formed from sequential observations. With this measurement, a pure displacement field can then be obtained by removal of the topographic contribution to the interferometric phase at each pixel. Further, they discuss how the vertical and horizontal components of displacement affect the interferometricallyderived motion field. They illustrate their approach with four successive (3day repeat) ERS1 images of a flow feature in northeastern Greenland 
@Article{kwokFahnestockTGRS1996DINSARicesheetmotion,
Title = {Ice sheet motion and topography from radar interferometry},
Author = {Kwok, R. and Fahnestock, M.A.},
Doi = {10.1109/36.481903},
ISSN = {01962892},
Month = jan,
Number = {1},
Pages = {189200},
Volume = {34},
Year = {1996},
Abstract = {Both topography and motion information are present in repeat pass ERS1 interferograms over ice sheets. The authors demonstrate that the topography is separable from the surface displacement field when a sequence of radar images are available. If the velocity field is constant over the time span of observation, the topography can be derived from differential interferograms formed from sequential observations. With this measurement, a pure displacement field can then be obtained by removal of the topographic contribution to the interferometric phase at each pixel. Further, they discuss how the vertical and horizontal components of displacement affect the interferometricallyderived motion field. They illustrate their approach with four successive (3day repeat) ERS1 images of a flow feature in northeastern Greenland},
Journal = {IEEE Trans. Geosci. Remote Sens.},
Keywords = {SAR Processing, Interferometry, SAR interferometry, differential SAR interferometry, DInSAR, Displacement, Surface Displacement, glaciology; hydrological techniques;radar applications;radar imaging;remote sensing by radar;spaceborne radar;synthetic aperture radar; Greenland;SAR method;flow;geophysical measurement technique;glaciology;hydrology;ice sheet motion;motion;polar ice sheet;radar interferometry; radar remote sensing;repeat pass ERS1 interferogram;surface displacement field;topography;velocity field;Data mining;Ice surface;Laboratories; Propulsion;Radar interferometry;Satellites;Space technology;Streaming media;Surface topography;Synthetic aperture radar},
Pdf = {../../../docs/kwokFahnestockTGRS1996DINSARicesheetmotion.pdf}
}

R. Lanari,
G. Fornaro,
D. Riccio,
M. Migliaccio,
Konstantinos P. Papathanassiou,
J.R. Moreira,
M. Schwabisch,
L. Dutra,
G. Puglisi,
G. Franceschetti,
and M. Coltelli.
Generation of digital elevation models by using SIRC/XSAR multifrequency twopass interferometry: the Etna case study.
IEEE Transactions on Geoscience and Remote Sensing,
34(5):10971114,
September 1996.
Keyword(s): Cband,
Etna,
Italy,
Kalman filter,
Lband,
SAR,
SHF,
SIR,
SIRC,
Sicily,
UHF,
XSAR,
Xband,
algorithm,
digital elevation model,
geology,
geophysical measurement technique,
land surface,
microwave radar,
multifrequency twopass interferometry,
radar imaging,
radar remote sensing,
spaceborne radar,
synthetic aperture radar,
terrain mapping,
topography,
unwrapped pattern,
unwrapping performance,
volcano,
Kalman filters,
geophysical techniques,
radar imaging,
remote sensing by radar,
spaceborne radar,
synthetic aperture radar,
topography (Earth),
volcanology.
Abstract: 
The authors exploit the interferometric multifrequency potentiality of the SIRC/XSAR system which is equipped with an L, C, and Xband sensor. They present a solution to improve the unwrapping performance of the C and Xband data by considering the Lband unwrapped pattern. A new algorithm for the generation of a single digital elevation model (DEM) combining L, C, and Xband information is presented. This solution is based on the fusion of the unwrapped phase patterns by using a Kalman filter. The proposed fusion operation also accounts for the coherence characteristics of the three data sets. The selected test site is the Mt. Etna region in Italy which is very interesting from the volcanological and geological point of view. Numerical assessments of the achieved results are provided by evaluating the height accuracy with respect to a reference DEM 
@Article{536526,
author = {Lanari, R. and Fornaro, G. and Riccio, D. and Migliaccio, M. and Papathanassiou, Konstantinos P. and Moreira, J.R. and Schwabisch, M. and Dutra, L. and Puglisi, G. and Franceschetti, G. and Coltelli, M.},
title = {Generation of digital elevation models by using SIRC/XSAR multifrequency twopass interferometry: the Etna case study},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1996},
volume = {34},
number = {5},
pages = {10971114},
month = {sep},
issn = {01962892},
abstract = {The authors exploit the interferometric multifrequency potentiality of the SIRC/XSAR system which is equipped with an L, C, and Xband sensor. They present a solution to improve the unwrapping performance of the C and Xband data by considering the Lband unwrapped pattern. A new algorithm for the generation of a single digital elevation model (DEM) combining L, C, and Xband information is presented. This solution is based on the fusion of the unwrapped phase patterns by using a Kalman filter. The proposed fusion operation also accounts for the coherence characteristics of the three data sets. The selected test site is the Mt. Etna region in Italy which is very interesting from the volcanological and geological point of view. Numerical assessments of the achieved results are provided by evaluating the height accuracy with respect to a reference DEM},
doi = {10.1109/36.536526},
keywords = {Cband;Etna;Italy;Kalman filter;Lband;SAR;SHF;SIR;SIRC;Sicily;UHF;XSAR;Xband;algorithm;digital elevation model;geology;geophysical measurement technique;land surface;microwave radar;multifrequency twopass interferometry;radar imaging;radar remote sensing;spaceborne radar;synthetic aperture radar;terrain mapping;topography;unwrapped pattern;unwrapping performance;volcano;Kalman filters;geophysical techniques;radar imaging;remote sensing by radar;spaceborne radar;synthetic aperture radar;topography (Earth);volcanology},
}

Christian Matzler.
Microwave permittivity of dry snow.
IEEE Transactions on Geoscience and Remote Sensing,
34(2):573581,
1996.
Keyword(s): UHF measurement,
hydrological equipment,
permittivity,
snow,
10 to 0 degC,
1 GHz,
Austrian Alps,
Swiss Alps,
average axial ratio,
coaxial sensor,
density,
destructive metamorphism,
dry snow,
ice grains,
ice volume fraction,
liquidlike surface layer,
microwave permittivity,
oblate spheroids,
physical mixing theory,
prolate spheroids,
relative dielectric constant,
relative permittivity,
resometer,
resonator,
sintering,
Coaxial components,
Dielectric constant,
Dielectric measurements,
Frequency,
Ice,
Instruments,
Measurement standards,
Permittivity measurement,
Snow,
Testing.
Abstract: 
The relative dielectric constant, or relative permittivity, \epsilon of dry snow, is independent of frequency from about 1 MHz up to the microwave range of at least 10 GHz. New measurements of with improved accuracy were made with a specially designed resonator operating near 1 GHz. The coaxial sensor accurately defines the sample volume whose actual mass can be determined to give the density of the snow sample. A special electronic instrument, called a resometer, enabled accurate and rapid measurements under field conditions. Some 90 measurements of different kinds of dry snow (fresh, old, windpressed snow, depth hear, and refrozen crusts) were made at test sites in the Swiss and Austrian Alps. The data indicate that \epsilon is a function of snow density only, given that the standard deviation of 0.006 from the fitted curve is just due to the expected measurement errors. The interpretation of these data in terms of physical mixing theory favors the effective medium formula of Polder and van Santen (1946). The data allow to relate the average axial ratio X as a function of ice volume fraction. Both prolate and oblate spheroids can explain the data. Independent reasoning gives preference to oblate particles. In both cases, the axial ratio increases with increasing fraction up to a critical value of 0.33, followed by a decrease at still higher fractions. The destructive metamorphism of slowly compacting snow explains the increase of X, while the following decrease might be due to sintering. So far, no effect on \epsilon by a liquidlike surface layer on the ice grains at temperatures between 10 deg C and 0 deg C has been observed 
@Article{matzlerTGRS1996MicrowavePermittivityDrySnow,
author = {Matzler, Christian},
title = {Microwave permittivity of dry snow},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1996},
volume = {34},
number = {2},
pages = {573581},
issn = {01962892},
abstract = {The relative dielectric constant, or relative permittivity, \epsilon of dry snow, is independent of frequency from about 1 MHz up to the microwave range of at least 10 GHz. New measurements of with improved accuracy were made with a specially designed resonator operating near 1 GHz. The coaxial sensor accurately defines the sample volume whose actual mass can be determined to give the density of the snow sample. A special electronic instrument, called a resometer, enabled accurate and rapid measurements under field conditions. Some 90 measurements of different kinds of dry snow (fresh, old, windpressed snow, depth hear, and refrozen crusts) were made at test sites in the Swiss and Austrian Alps. The data indicate that \epsilon is a function of snow density only, given that the standard deviation of 0.006 from the fitted curve is just due to the expected measurement errors. The interpretation of these data in terms of physical mixing theory favors the effective medium formula of Polder and van Santen (1946). The data allow to relate the average axial ratio X as a function of ice volume fraction. Both prolate and oblate spheroids can explain the data. Independent reasoning gives preference to oblate particles. In both cases, the axial ratio increases with increasing fraction up to a critical value of 0.33, followed by a decrease at still higher fractions. The destructive metamorphism of slowly compacting snow explains the increase of X, while the following decrease might be due to sintering. So far, no effect on \epsilon by a liquidlike surface layer on the ice grains at temperatures between 10 deg C and 0 deg C has been observed},
doi = {10.1109/36.485133},
file = {:matzlerTGRS1996MicrowavePermittivityDrySnow.pdf:PDF},
keywords = {UHF measurement, hydrological equipment, permittivity, snow, 10 to 0 degC, 1 GHz, Austrian Alps, Swiss Alps, average axial ratio, coaxial sensor, density, destructive metamorphism, dry snow, ice grains, ice volume fraction, liquidlike surface layer, microwave permittivity, oblate spheroids, physical mixing theory, prolate spheroids, relative dielectric constant, relative permittivity, resometer, resonator, sintering, Coaxial components, Dielectric constant, Dielectric measurements, Frequency, Ice, Instruments, Measurement standards, Permittivity measurement, Snow, Testing},
owner = {ofrey},
pdf = {../../../docs/matzlerTGRS1996MicrowavePermittivityDrySnow.pdf},
publisher = {IEEE},
}

Andrea MontiGuarnieri.
Residual SAR Focusing: An Application to Coherence Improvement.
IEEE Transactions on Geoscience and Remote Sensing,
34(1):201211,
January 1996.
Keyword(s): SAR Processing,
Interferometry,
Residual Azimuth Compression,
Coherence Improvement.
Abstract: 
The focusing quality of a SAR processor greatly depends on the accuracy of the system geometry estimate. Sometimes ancillary data do not provide enough accuracy, therefore autofocusing has to be performed to get the finest quality possible. A residual azimuth compression is introduced to show how a defocused image can be compensated by means of a monodimensional local operator. The residual transfer function that generates defocusing is then derived. The effects of the defocusing are shown on both a complex single SAR image and a SAR interferogram. SAR interferograms, however, are much more sensitive to defocusing than the single SAR image. Two algorithms have been developed to estimate, and compensate for, the defocusing in both the single SAR image and SAR interferometric cases. The processors select data suitable for estimating focusing parameters from the whole images by exploring Kurtosis (for single image focusing) or coherence (for interferometric autofocusing). The residual, short timedomain operator is then exploited to retrieve the focusing parameter values and, finally, to get the focused image. The limitations and accuracy of the algorithm in terms of parameter estimation are investigated. Experimental results, obtained from different SAR missions, are presented 
@Article{monti:resSARfoc,
Title = {{Residual SAR Focusing: An Application to Coherence Improvement}},
Author = {Andrea MontiGuarnieri},
Month = Jan,
Number = {1},
Pages = {201211},
Url = {http://ieeexplore.ieee.org/iel1/36/10297/00481904.pdf},
Volume = {34},
Year = {1996},
Abstract = {The focusing quality of a SAR processor greatly depends on the accuracy of the system geometry estimate. Sometimes ancillary data do not provide enough accuracy, therefore autofocusing has to be performed to get the finest quality possible. A residual azimuth compression is introduced to show how a defocused image can be compensated by means of a monodimensional local operator. The residual transfer function that generates defocusing is then derived. The effects of the defocusing are shown on both a complex single SAR image and a SAR interferogram. SAR interferograms, however, are much more sensitive to defocusing than the single SAR image. Two algorithms have been developed to estimate, and compensate for, the defocusing in both the single SAR image and SAR interferometric cases. The processors select data suitable for estimating focusing parameters from the whole images by exploring Kurtosis (for single image focusing) or coherence (for interferometric autofocusing). The residual, short timedomain operator is then exploited to retrieve the focusing parameter values and, finally, to get the focused image. The limitations and accuracy of the algorithm in terms of parameter estimation are investigated. Experimental results, obtained from different SAR missions, are presented},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {SAR Processing, Interferometry, Residual Azimuth Compression, Coherence Improvement},
Pdf = {../../../docs/monti96.pdf}
}

Alberto Moreira,
Josef Mittermayer,
and Rolf Scheiber.
Extended Chirp Scaling Algorithm for Air and Spaceborne SAR Data Processing in Stripmap and ScanSAR Imaging Modes.
IEEE Transactions on Geoscience and Remote Sensing,
34(5):11231136,
September 1996.
Keyword(s): SAR Processing,
Chirp Scaling Algorithm,
Extended Chirp Scaling Algorithm,
Spaceborne SAR,
Airborne SAR,
ScanSAR,
Automatic Azimuth Coregistration,
Azimuth Scaling,
Squinted SAR,
Interferometry,
PhasePreserving Processing,
Range Scaling Formulation,
Stripmap SAR,
Subaperture Processing,
Terrain Mapping.
Abstract: 
This paper resents a generalized formulation of the extended chirp scaling (ECS) approach for high precision processing of air and spaceborne SAR data. Based on the original chirp scaling function, the ECS algorithm incorporates a new azimuth scaling function and a subaperture approach, which allow an effective phasepreserving processing of ScanSAR data without interpolation for azimuth geometric correction. The azimuth scaling can also be used for automatic azimuth coregistration of interferometric image pairs which are acquired with different sampling distances. Additionally, a novel range scaling formulation is proposed for automatic range coregistration of interferometric image pairs or for improved robustness for the processing of highly squinted data. Several simulation and processing results of air and spaceborne SAR data are presented to demonstrate the validity of the proposed algorithms 
@Article{moreiraMittermayerScheiber96:Extended,
Title = {{Extended Chirp Scaling Algorithm for Air and Spaceborne SAR Data Processing in Stripmap and ScanSAR Imaging Modes}},
Author = {Alberto Moreira and Josef Mittermayer and Rolf Scheiber},
Month = sep,
Number = {5},
Pages = {11231136},
Url = {http://ieeexplore.ieee.org/iel1/36/11515/00536528.pdf},
Volume = {34},
Year = {1996},
Abstract = {This paper resents a generalized formulation of the extended chirp scaling (ECS) approach for high precision processing of air and spaceborne SAR data. Based on the original chirp scaling function, the ECS algorithm incorporates a new azimuth scaling function and a subaperture approach, which allow an effective phasepreserving processing of ScanSAR data without interpolation for azimuth geometric correction. The azimuth scaling can also be used for automatic azimuth coregistration of interferometric image pairs which are acquired with different sampling distances. Additionally, a novel range scaling formulation is proposed for automatic range coregistration of interferometric image pairs or for improved robustness for the processing of highly squinted data. Several simulation and processing results of air and spaceborne SAR data are presented to demonstrate the validity of the proposed algorithms},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {SAR Processing, Chirp Scaling Algorithm, Extended Chirp Scaling Algorithm, Spaceborne SAR, Airborne SAR, ScanSAR, Automatic Azimuth Coregistration, Azimuth Scaling, Squinted SAR, Interferometry, PhasePreserving Processing, Range Scaling Formulation, Stripmap SAR, Subaperture Processing, Terrain Mapping},
Owner = {ofrey},
Pdf = {../../../docs/moreiraMittermayerScheiber96.pdf}
}

Kamal Sarabandi and TsenChieh Chiu.
Optimum corner reflectors for calibration of imaging radars.
IEEE Transactions on Antennas and Propagation,
44(10):13481361,
October 1996.
Keyword(s): calibration,
electromagnetic wave reflection,
geometrical optics,
microwave measurement,
optimisation,
physical optics,
radar crosssections,
radar equipment,
1dB RCS beamwidths,
9.5 GHz,
RCS,
SHF,
UHF,
backscatter measurements,
calibration,
coherent interaction,
edge length,
geometrical optics,
ground plane,
imaging radar,
low microwave frequencies,
nearfield physical optics,
optimum corner reflector,
optimum corner reflectors,
panel geometry,
polygonal selfilluminating corner reflectors,
radar cross section,
selfilluminating corner reflectors,
total surface area,
Azimuth,
Calibration,
Geometrical optics,
Microwave frequencies,
Microwave imaging,
Optical imaging,
Physical optics,
Radar cross section,
Radar imaging,
Uncertainty.
Abstract: 
Trihedral corner reflectors are widely used as calibration targets for imaging radars because of their large radar cross section (RCS) and extremely wide RCS pattern. An important source of uncertainty in the RCS of a trihedral sitting on a ground plane is the coherent interaction of the ground plane with the trihedral. At UHF and low microwave frequencies the large physical size of corner reflectors become a limiting factor in regard to difficulties in field deployment and deviation of their RCS from the expected values. In this paper, a general class of corner reflectors with highaperture efficiency referred to as selfilluminating corner reflectors, is introduced whose coherent interaction with the surrounding terrain is minimized and their total surface area is twothirds of that of a triangular corner reflector having the same maximum RCS. Analytical expressions based on geometrical optics and a new numerical solution based on nearfield physical optics for the RCS of two simple selfilluminating corner reflectors are presented and compared with backscatter measurements. Also the panel geometry for an optimum corner reflector which has the shortest edge length among polygonal selfilluminating corner reflectors is obtained. Highaperture efficiency is achieved at the expense of azimuth and elevation beamwidth. It is shown that the 1dB RCS beamwidths of the optimal corner reflectors, both in azimuth and elevation directions, are about 16 deg. RCS measurements of corner reflectors in the presence of a ground plane show that the RCS of selfilluminating corner reflectors are less affected by the coherent ground interaction 
@Article{sarabandiChiuTGARS1996OptimumCornerReflectorsForCalibration,
author = {Kamal Sarabandi and TsenChieh Chiu},
title = {Optimum corner reflectors for calibration of imaging radars},
journal = {IEEE Transactions on Antennas and Propagation},
year = {1996},
volume = {44},
number = {10},
month = oct,
pages = {13481361},
issn = {0018926X},
doi = {10.1109/8.537329},
abstract = {Trihedral corner reflectors are widely used as calibration targets for imaging radars because of their large radar cross section (RCS) and extremely wide RCS pattern. An important source of uncertainty in the RCS of a trihedral sitting on a ground plane is the coherent interaction of the ground plane with the trihedral. At UHF and low microwave frequencies the large physical size of corner reflectors become a limiting factor in regard to difficulties in field deployment and deviation of their RCS from the expected values. In this paper, a general class of corner reflectors with highaperture efficiency referred to as selfilluminating corner reflectors, is introduced whose coherent interaction with the surrounding terrain is minimized and their total surface area is twothirds of that of a triangular corner reflector having the same maximum RCS. Analytical expressions based on geometrical optics and a new numerical solution based on nearfield physical optics for the RCS of two simple selfilluminating corner reflectors are presented and compared with backscatter measurements. Also the panel geometry for an optimum corner reflector which has the shortest edge length among polygonal selfilluminating corner reflectors is obtained. Highaperture efficiency is achieved at the expense of azimuth and elevation beamwidth. It is shown that the 1dB RCS beamwidths of the optimal corner reflectors, both in azimuth and elevation directions, are about 16 deg. RCS measurements of corner reflectors in the presence of a ground plane show that the RCS of selfilluminating corner reflectors are less affected by the coherent ground interaction},
keywords = {calibration;electromagnetic wave reflection;geometrical optics;microwave measurement;optimisation;physical optics;radar crosssections;radar equipment;1dB RCS beamwidths;9.5 GHz;RCS;SHF;UHF;backscatter measurements;calibration;coherent interaction;edge length;geometrical optics;ground plane;imaging radar;low microwave frequencies;nearfield physical optics;optimum corner reflector;optimum corner reflectors;panel geometry;polygonal selfilluminating corner reflectors;radar cross section;selfilluminating corner reflectors;total surface area;Azimuth;Calibration;Geometrical optics;Microwave frequencies;Microwave imaging;Optical imaging;Physical optics;Radar cross section;Radar imaging;Uncertainty},
owner = {ofrey},
}

M. Soumekh.
Reconnaissance with slant plane circular SAR imaging.
Image Processing, IEEE Transactions on,
5(8):12521265,
1996.
Keyword(s): SAR Processing,
NonLinear Flight Path,
Fourier analysis,
Fourier transforms,
Green's function methods,
image reconstruction,
image resolution,
inverse problems,
radar imaging,
synthetic aperture radar,
Fourier analysis,
Green's function,
SAR data inversion,
SAR system,
aspect angle,
circular flight path,
full rotation,
ground penetrating UHF radar signature,
image resolution,
imaging system,
partial segment,
reconnaissance,
reconstruction algorithm,
simulated target,
slant plane circular SAR imaging,
slant plane data,
slant plane linear SAR,
synthetic aperture radar,
target scene,
threedimensional imaging,
ultrawideband foliage penetrating radar signature.
Abstract: 
This paper presents a method for imaging from the slant plane data collected by a synthetic aperture radar (SAR) over the full rotation or a partial segment of a circular flight path. A Fourier analysis for the Green's function of the imaging system is provided. This analysis is the basis of an inversion for slant plane circular SAR data. The reconstruction algorithm and resolution for this SAR system are outlined. It is shown that the slant plane circular SAR, unlike the slant plane linear SAR, has the capability to extract threedimensional imaging information of a target scene. The merits of the algorithm are demonstrated via a simulated target whose ultra wideband foliage penetrating (FOPEN) or ground penetrating (GPEN) ultrahigh frequency (UHF) radar signature varies with the radar's aspect angle 
@Article{Soumekh1996,
Title = {Reconnaissance with slant plane circular SAR imaging},
Author = {Soumekh, M.},
ISSN = {10577149},
Number = {8},
Pages = {12521265},
Url = {http://ieeexplore.ieee.org/iel4/83/11100/00506760.pdf},
Volume = {5},
Year = {1996},
Abstract = {This paper presents a method for imaging from the slant plane data collected by a synthetic aperture radar (SAR) over the full rotation or a partial segment of a circular flight path. A Fourier analysis for the Green's function of the imaging system is provided. This analysis is the basis of an inversion for slant plane circular SAR data. The reconstruction algorithm and resolution for this SAR system are outlined. It is shown that the slant plane circular SAR, unlike the slant plane linear SAR, has the capability to extract threedimensional imaging information of a target scene. The merits of the algorithm are demonstrated via a simulated target whose ultra wideband foliage penetrating (FOPEN) or ground penetrating (GPEN) ultrahigh frequency (UHF) radar signature varies with the radar's aspect angle},
Booktitle = {Image Processing, IEEE Transactions on},
Journal = {Image Processing, IEEE Transactions on},
Keywords = {SAR Processing, NonLinear Flight Path, Fourier analysis, Fourier transforms, Green's function methods, image reconstruction, image resolution, inverse problems, radar imaging, synthetic aperture radar, Fourier analysis, Green's function, SAR data inversion, SAR system, aspect angle, circular flight path, full rotation, ground penetrating UHF radar signature, image resolution, imaging system, partial segment, reconnaissance, reconstruction algorithm, simulated target, slant plane circular SAR imaging, slant plane data, slant plane linear SAR, synthetic aperture radar, target scene, threedimensional imaging, ultrawideband foliage penetrating radar signature},
Owner = {ofrey},
Pdf = {../../../docs/soumekh1996.pdf}
}

Robert N. Treuhaft,
Soren N. Madsen,
Mahta Moghaddam,
and Jakob van Zyl.
Vegetation characteristics and underlying topography from interferometric radar.
Radio Science,
31(6):14491485,
1996.
Keyword(s): SAR Processing,
InSAR,
Interferometry,
Vegetation Parameters,
Parameter Extraction,
Topography,
SAR Tomography.
Abstract: 
This paper formulates and demonstrates methods for extracting vegetation characteristics and underlying ground surface topography from interferometric synthetic aperture radar (INSAR) data. The electromagnetic scattering and radar processing, which produce the INSAR observations, are modeled, vegetation and topographic parameters are identified for estimation, the parameter errors are assessed in terms of INSAR instrumental performance, and the parameter estimation is demonstrated on INSAR data and compared to ground truth. The fundamental observations from which vegetation and surface topographic parameters are estimated are (1) the crosscorrelation amplitude, (2) the crosscorrelation phase, and (3) the synthetic aperture radar (SAR) backscattered power. A calculation based on scattering from vegetation treated as a random medium, including the effects of refractivity and absorption in the vegetation, yields expressions for the complex cross correlation and backscattered power in terms of vegetation characteristics. These expressions lead to the identification of a minimal set of four parameters describing the vegetation and surface topography: (1) the vegetation layer depth, (2) the vegetation extinction coefficient (power loss per unit length), (3) a parameter involving the product of the average backscattering amplitude and scatterer number density, and (4) the height of the underlying ground surface. The accuracy of vegetation and ground surface parameters, as a function of INSAR observation accuracy, is evaluated for aircraft INSAR, which is characterized by a 2.5 m baseline, an altitude of about 8 km, and a wavelength of 5.6 cm. It is found that for ~0.5% accuracy in the INSAR normalized crosscorrelation amplitude and ~5% accuracy in the interferometric phase, fewmeter vegetation layer depths and ground surface heights can be determined from INSAR for many types of vegetation layers. With the same observational accuracies, extinction coefficients can be estimated at the 0.1dB/m level. Because the number of parameters exceeds the number of observations for current INSAR data sets, external extinction coefficient data are used to demonstrate the estimation of the vegetation layer depth and ground surface height from INSAR data taken at the Bonanza Creek Experimental Forest in Alaska. This demonstration shows approximately 5 m average ground truth agreement for vegetation layer depths and groundsurface heights, with a clear dependence of error on stand height. These errors suggest refinements in INSAR data acquisition and analysis techniques which will potentially yield fewmeter accuracies. The information in the INSAR parameters is applicable to a variety of ecological modeling issues including the successional modeling of forested ecosystems. 
@Article{treuhaftMadsenMoghaddamVanZyl96:.pdf,
Title = {Vegetation characteristics and underlying topography from interferometric radar},
Author = {Robert N. Treuhaft and S{\o}ren N. Madsen and Mahta Moghaddam and Jakob van Zyl},
Number = {6},
Pages = {14491485},
Volume = {31},
Year = {1996},
Abstract = {This paper formulates and demonstrates methods for extracting vegetation characteristics and underlying ground surface topography from interferometric synthetic aperture radar (INSAR) data. The electromagnetic scattering and radar processing, which produce the INSAR observations, are modeled, vegetation and topographic parameters are identified for estimation, the parameter errors are assessed in terms of INSAR instrumental performance, and the parameter estimation is demonstrated on INSAR data and compared to ground truth. The fundamental observations from which vegetation and surface topographic parameters are estimated are (1) the crosscorrelation amplitude, (2) the crosscorrelation phase, and (3) the synthetic aperture radar (SAR) backscattered power. A calculation based on scattering from vegetation treated as a random medium, including the effects of refractivity and absorption in the vegetation, yields expressions for the complex cross correlation and backscattered power in terms of vegetation characteristics. These expressions lead to the identification of a minimal set of four parameters describing the vegetation and surface topography: (1) the vegetation layer depth, (2) the vegetation extinction coefficient (power loss per unit length), (3) a parameter involving the product of the average backscattering amplitude and scatterer number density, and (4) the height of the underlying ground surface. The accuracy of vegetation and ground surface parameters, as a function of INSAR observation accuracy, is evaluated for aircraft INSAR, which is characterized by a 2.5 m baseline, an altitude of about 8 km, and a wavelength of 5.6 cm. It is found that for ~0.5% accuracy in the INSAR normalized crosscorrelation amplitude and ~5% accuracy in the interferometric phase, fewmeter vegetation layer depths and ground surface heights can be determined from INSAR for many types of vegetation layers. With the same observational accuracies, extinction coefficients can be estimated at the 0.1dB/m level. Because the number of parameters exceeds the number of observations for current INSAR data sets, external extinction coefficient data are used to demonstrate the estimation of the vegetation layer depth and ground surface height from INSAR data taken at the Bonanza Creek Experimental Forest in Alaska. This demonstration shows approximately 5 m average ground truth agreement for vegetation layer depths and groundsurface heights, with a clear dependence of error on stand height. These errors suggest refinements in INSAR data acquisition and analysis techniques which will potentially yield fewmeter accuracies. The information in the INSAR parameters is applicable to a variety of ecological modeling issues including the successional modeling of forested ecosystems.},
Journal = {Radio Science},
Keywords = {SAR Processing, InSAR, Interferometry, Vegetation Parameters, Parameter Extraction, Topography, SAR Tomography},
Owner = {ofrey},
Pdf = {../../../docs/treuhaftMadsenMoghaddamVanZyl96.pdf}
}

Lars M. H. Ulander.
Radiometric slope correction of syntheticaperture radar images.
IEEE Transactions on Geoscience and Remote Sensing,
34(5):11151122,
1996.
Keyword(s): SAR Processing,
Radiometric Correction,
Topography,
geophysical techniques,
radar imaging,
remote sensing by radar,
spaceborne radar,
synthetic aperture radar,
SAR,
algorithm,
calibration equation,
fringe frequencies,
geophysical measurement technique,
land surface,
maximumlikelihood estimator,
radar imaging,
radar remote sensing,
radiometric slope correction,
spaceborne radar,
synthetic aperture radar image,
terrain mapping,
topographic height variation.
Abstract: 
The brightness in a SAR image is affected by topographic height 
@Article{Ulander96:RadiometricSlopeCorection,
author = {Ulander, Lars M. H.},
title = {{Radiometric slope correction of syntheticaperture radar images}},
journal = {IEEE Transactions on Geoscience and Remote Sensing},
year = {1996},
volume = {34},
number = {5},
pages = {11151122},
abstract = {The brightness in a SAR image is affected by topographic height},
file = {:Ulander96.pdf:PDF},
keywords = {SAR Processing, Radiometric Correction, Topography, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, SAR, algorithm, calibration equation, fringe frequencies, geophysical measurement technique, land surface, maximumlikelihood estimator, radar imaging, radar remote sensing, radiometric slope correction, spaceborne radar, synthetic aperture radar image, terrain mapping, topographic height variation},
owner = {ofrey},
pdf = {../../../docs/Ulander96.pdf},
url = {http://ieeexplore.ieee.org/iel1/36/11515/00536527.pdf},
}

Frank Wong and Ian G. Cumming.
A Combined SAR Doppler Centroid Estimation Scheme Based Upon Signal Phase.
IEEE Transactions on Geoscience and Remote Sensing,
34(3):696707,
May 1996.
Keyword(s): SAR Processing,
Doppler Centroid,
Doppler Centroid Estimation,
Multilook Cross Correlation,
MLCC,
Multilook Beat Frequency,
MLBF,
Clutterlock,
Doppler Ambiguity Resolver,
DAR.
Abstract: 
This paper describes a complete endtoend Doppler centroid estimation scheme, which determines the fractional PRF part of the Doppler centroid. It also resolves the Doppler ambiguity. Experiments show that the scheme works successfully over various terrain types, including land, water, and ice, and that it requires only a modest amount of SAR data to perform reliably. The proposed scheme has an added advantage that it is directly applicable to RADARSAT and ENVISAT ScanSAR data. The scheme uses two complementary Doppler estimation algorithms, both utilizing the phase information embedded in the radar signal. In each algorithm, upper and lower parts of the available bandwidth of the received signal are extracted to form two range looks. The first algorithm, called multilook cross correlation (MLCC), computes the average cross correlation coefficient between adjacent azimuth samples for each of the two looks and then takes the difference between the angles of the two coefficients. The Doppler ambiguity is determined from the angle difference. The fractional pulse repetition frequency (PRF) part is also determined from the cross correlation coefficients. In the second algorithm, called multilook beat frequency (MLBF), the two looks are multiplied together to generate a beat signal. The beat frequency is then estimated and the Doppler ambiguity determined from the beat frequency. The MLCC algorithm performs better with low contrast scenes while the MLBF works better with high contrast ones. Although each algorithm works well on its own with sufficient averaging, it is also possible to use quality measures to select the best result from either algorithm. In this way, scenes of different content or contrast can be handled reliably. This paper presents the analysis of the two algorithms, explaining why their performance is affected by scene contrast, which is confirmed by experimental results with ERS1 and JERS1 data. 
@Article{wongCum:DopCentrEstim,
Title = {{A Combined SAR Doppler Centroid Estimation Scheme Based Upon Signal Phase}},
Author = {Frank Wong and Ian G. Cumming},
Month = May,
Number = {3},
Pages = {696707},
Volume = {34},
Year = {1996},
Abstract = {This paper describes a complete endtoend Doppler centroid estimation scheme, which determines the fractional PRF part of the Doppler centroid. It also resolves the Doppler ambiguity. Experiments show that the scheme works successfully over various terrain types, including land, water, and ice, and that it requires only a modest amount of SAR data to perform reliably. The proposed scheme has an added advantage that it is directly applicable to RADARSAT and ENVISAT ScanSAR data. The scheme uses two complementary Doppler estimation algorithms, both utilizing the phase information embedded in the radar signal. In each algorithm, upper and lower parts of the available bandwidth of the received signal are extracted to form two range looks. The first algorithm, called multilook cross correlation (MLCC), computes the average cross correlation coefficient between adjacent azimuth samples for each of the two looks and then takes the difference between the angles of the two coefficients. The Doppler ambiguity is determined from the angle difference. The fractional pulse repetition frequency (PRF) part is also determined from the cross correlation coefficients. In the second algorithm, called multilook beat frequency (MLBF), the two looks are multiplied together to generate a beat signal. The beat frequency is then estimated and the Doppler ambiguity determined from the beat frequency. The MLCC algorithm performs better with low contrast scenes while the MLBF works better with high contrast ones. Although each algorithm works well on its own with sufficient averaging, it is also possible to use quality measures to select the best result from either algorithm. In this way, scenes of different content or contrast can be handled reliably. This paper presents the analysis of the two algorithms, explaining why their performance is affected by scene contrast, which is confirmed by experimental results with ERS1 and JERS1 data.},
Comment = {+ Description on how to estimate the Doppler centroid frequency from raw data.},
Journal = {IEEE Transactions on Geoscience and Remote Sensing},
Keywords = {SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Multilook Cross Correlation, MLCC, Multilook Beat Frequency, MLBF, Clutterlock, Doppler Ambiguity Resolver, DAR},
Pdf = {../../../docs/WonCum96.pdf}
}
Conference articles

G. Cazzaniga and Andrea MontiGuarnieri.
Removing RF interferences from Pband airplane SAR data.
In Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International,
volume 3,
pages 18451847,
1996.
Keyword(s): SAR Processing,
geophysical signal processing,
geophysical techniques,
interference,
interference (signal),
interference filters,
notch filters,
radar imaging,
radar interference,
remote sensing by radar,
synthetic aperture radar,
MUSIC,
PBand,
RFI Suppression,
RF interference removal,
UHF radar,
adaptive signal processing,
airborne radar,
airborne SAR,
geophysical measurement technique,
inphase subtraction,
land surface,
notch filtering,
radar imaging,
radar remote sensing,
synthetic aperture radar,
terrain mapping,
urban area.
Abstract: 
This paper approaches the problem of canceling the disturbances due to RF interferences in Pband, airborne SAR missions. Two techniques are introduced: one exploits MUSIC to estimate the interferences' frequencies, and then performs notch filtering at that frequencies; whereas the other adaptively estimate the interference contributions and cancel them by means of inphase subtraction. Both techniques have been successfully tested on the data acquired by the DLR ESAR sensor over urban areas. 
@InProceedings{cazzanigaMontiGuarnieri96:RFI,
Title = {Removing RF interferences from Pband airplane SAR data},
Author = {Cazzaniga, G. and MontiGuarnieri, Andrea},
Booktitle = {Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International},
Pages = {18451847},
Url = {http://ieeexplore.ieee.org/iel3/3772/11018/00516816.pdf},
Volume = {3},
Year = {1996},
Abstract = {This paper approaches the problem of canceling the disturbances due to RF interferences in Pband, airborne SAR missions. Two techniques are introduced: one exploits MUSIC to estimate the interferences' frequencies, and then performs notch filtering at that frequencies; whereas the other adaptively estimate the interference contributions and cancel them by means of inphase subtraction. Both techniques have been successfully tested on the data acquired by the DLR ESAR sensor over urban areas.},
Keywords = {SAR Processing, geophysical signal processing, geophysical techniques, interference, interference (signal), interference filters, notch filters, radar imaging, radar interference, remote sensing by radar, synthetic aperture radar, MUSIC, PBand, RFI Suppression, RF interference removal, UHF radar, adaptive signal processing, airborne radar, airborne SAR, geophysical measurement technique, inphase subtraction, land surface, notch filtering, radar imaging, radar remote sensing, synthetic aperture radar, terrain mapping, urban area},
Owner = {ofrey},
Pdf = {../../../docs/cazzanigaMontiGuarnieri96.pdf}
}

F. Gatelli,
Andrea MontiGuarnieri,
Claudio Prati,
and Fabio Rocca.
Medium resolution efficient phase preserving focusing for interferometry.
In IGARSS '96, International Geoscience and Remote Sensing Symposium,
volume 1,
pages 671673,
1996.
Keyword(s): SAR Processing,
Presumming,
Interferometry,
geophysical signal processing,
geophysical techniques,
image processing,
image resolution,
radar imaging,
radar signal processing,
synthetic aperture radar,
SAR imagery,
SAR interferometry,
Unix Workstations,
algorithm,
coherence map,
geophysical measurement technique,
geophysics computing,
image pair,
image processing,
image resolution,
land surface,
medium resolution efficient phase preserving focusing,
radar imaging,
radar remote sensing,
radar signal processing,
real time method,
stripmap SAR interferogram,
synthetic aperture radar,
terrain mapping.
Abstract: 
A real time technique to get stripmap SAR interferograms and coherence maps with common Unix Workstations is presented. For the ERS mission, the ?real time? throughput corresponds to approximately 1/8 of PRF: e.g. ~4 min for processing a 100?100 km image pair. The proposed algorithm achieves that goal on a medium cost 160 Mflops/s Unix Workstation. The output is a 5 looks averaged interferogram, with a geometric resolution of 50?50. 
@InProceedings{gatelliMontiGuarnieriPratiRocca96:QuicklookPresumming,
Title = {Medium resolution efficient phase preserving focusing for interferometry},
Author = {Gatelli, F. and MontiGuarnieri, Andrea and Prati, Claudio and Rocca, Fabio},
Booktitle = {IGARSS '96, International Geoscience and Remote Sensing Symposium},
Pages = {671673},
Url = {http://ieeexplore.ieee.org/iel3/3772/11016/00516438.pdf},
Volume = {1},
Year = {1996},
Abstract = {A real time technique to get stripmap SAR interferograms and coherence maps with common Unix Workstations is presented. For the ERS mission, the ?real time? throughput corresponds to approximately 1/8 of PRF: e.g. ~4 min for processing a 100?100 km image pair. The proposed algorithm achieves that goal on a medium cost 160 Mflops/s Unix Workstation. The output is a 5 looks averaged interferogram, with a geometric resolution of 50?50.},
Keywords = {SAR Processing, Presumming,Interferometry,geophysical signal processing, geophysical techniques, image processing, image resolution, radar imaging, radar signal processing, synthetic aperture radar, SAR imagery, SAR interferometry, Unix Workstations, algorithm, coherence map, geophysical measurement technique, geophysics computing, image pair, image processing, image resolution, land surface, medium resolution efficient phase preserving focusing, radar imaging, radar remote sensing, radar signal processing, real time method, stripmap SAR interferogram, synthetic aperture radar, terrain mapping},
Owner = {ofrey},
Pdf = {../../../docs/gatelliMontiGuarnieriPratiRocca96.pdf}
}

H. Hellsten,
Lars M. H. Ulander,
A. Gustavsson,
and B. Larsson.
Development of VHF CARABAS II SAR.
In Proc. SPIE,
volume 2747,
pages 4860,
June 1996.
@InProceedings{hellstenUlanderGustavsson1996:CARABASII,
Title = {Development of {VHF} {CARABAS~II} {SAR}},
Author = {{Hellsten}, H. and {Ulander}, Lars M. H. and {Gustavsson}, A. and {Larsson}, B.},
Booktitle = {Proc. SPIE},
Month = jun,
Pages = {4860},
Volume = {2747},
Year = {1996},
Adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

J. Homer,
I.D. Longstaff,
and G. Callaghan.
High resolution 3D SAR via multibaseline interferometry.
In IEEE International Geoscience and Remote Sensing Symposium, IGARSS'96,
volume 1,
pages 796798,
May 1996.
Keyword(s): SAR Processing,
SAR Tomography,
Tomography,
geophysical techniques,
radar imaging,
remote sensing by radar,
spaceborne radar,
synthetic aperture radar,
topography (Earth)3D imagery,
InSAR,
Multibaseline Interferometry,
SAR imaging,
azimuth resolving capability,
geophysical measurment technique,
interferometric SAR,
land surface topography,
node aperture,
normaltoslantrange direction,
procedural outline,
radar remote sensing,
spaceborne radar,
synthetic aperture radar,
terrain height,
terrain mapping,
theoretical analysis,
three dimensional SAR method.
Abstract: 
The ability of interferometric SAR (InSAR) to provide terrain height estimation can be interpreted as being due to the baseline (of the two SAR imaging flight paths) acting as an aperture in the normaltoslantrange (n&oarr;) direction. However, the aperture, because it consists of only two nodes, has effectively no resolving power. The authors introduce and examine a technique which synthesises an N>2 node aperture in the n&oarr; direction from N1 connected baselines. This, together with the slantrange and azimuth resolving capability of SAR imaging systems, enables the generation of high resolution 3D imagery. A theoretical analysis and procedural outline of the proposed technique are presented 
@InProceedings{homerLongstaffCallaghan1996:Tomo,
Title = {{High resolution 3D SAR via multibaseline interferometry}},
Author = {Homer, J. and Longstaff, I.D. and Callaghan, G.},
Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS'96},
Doi = {10.1109/IGARSS.1996.516478},
Month = {May},
Pages = {796798},
Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=00516478},
Volume = {1},
Year = {1996},
Abstract = {The ability of interferometric SAR (InSAR) to provide terrain height estimation can be interpreted as being due to the baseline (of the two SAR imaging flight paths) acting as an aperture in the normaltoslantrange (n&oarr;) direction. However, the aperture, because it consists of only two nodes, has effectively no resolving power. The authors introduce and examine a technique which synthesises an N>2 node aperture in the n&oarr; direction from N1 connected baselines. This, together with the slantrange and azimuth resolving capability of SAR imaging systems, enables the generation of high resolution 3D imagery. A theoretical analysis and procedural outline of the proposed technique are presented},
Keywords = {SAR Processing, SAR Tomography, Tomography, geophysical techniques, radar imaging, remote sensing by radar, spaceborne radar, synthetic aperture radar, topography (Earth)3D imagery, InSAR, Multibaseline Interferometry, SAR imaging, azimuth resolving capability, geophysical measurment technique, interferometric SAR, land surface topography, node aperture, normaltoslantrange direction, procedural outline, radar remote sensing, spaceborne radar, synthetic aperture radar, terrain height, terrain mapping, theoretical analysis, three dimensional SAR method},
Owner = {ofrey},
Pdf = {../../../docs/homerLongstaffCallaghan1996.pdf}
}

Charles V. Jakowatz,
Daniel E. Wahl,
and Paul A. Thompson.
Ambiguity resolution in SAR interferometry by use of three phase centers.
In Edmund G. Zelnio and Robert J. Douglass, editors,
,
volume 2757,
pages 8291,
1996.
SPIE.
Keyword(s): SAR Processing,
InSAR,
SAR Interferometry,
multibaseline,
Multibaseline InSAR,
Three phase centers,
Terrain Mapping,
Topography,
Spotlight SAR,
Spotlightmode data.
@Conference{jakowatzWahlThompsonAmbiguityResolutionInSARByThreeAntennas,
author = {Charles V. Jakowatz and Daniel E. Wahl and Paul A. Thompson},
title = {Ambiguity resolution in {SAR} interferometry by use of three phase centers},
year = {1996},
editor = {Edmund G. Zelnio and Robert J. Douglass},
volume = {2757},
number = {1},
pages = {8291},
publisher = {SPIE},
doi = {10.1117/12.242025},
file = {:jakowatzWahlThompsonAmbiguityResolutionInSARByThreeAntennas.pdf:PDF},
journal = {Algorithms for Synthetic Aperture Radar Imagery III},
keywords = {SAR Processing, InSAR, SAR Interferometry, multibaseline, Multibaseline InSAR, Three phase centers, Terrain Mapping, Topography, Spotlight SAR, Spotlightmode data},
location = {Orlando, FL, USA},
owner = {ofrey},
pdf = {../../../docs/jakowatzWahlThompsonAmbiguityResolutionInSARByThreeAntennas.pdf},
url = {http://link.aip.org/link/?PSI/2757/82/1},
}

Kenneth Knaell.
Threedimensional SAR from curvilinear apertures.
In Radar Conference, 1996., Proceedings of the 1996 IEEE National,
pages 220225,
1996.
Keyword(s): SAR Processing,
NonLinear Flight Path,
SAR Tomography,
curvilinear SAR,
image enhancement,
interference suppression,
maximum likelihood estimation,
radar antennas,
radar clutter,
radar crosssections,
radar imaging,
synthetic aperture radar,
IMP algorithm,
aperture configuration,
artifacts,
coherent CLEAN algorithm,
curvilinear apertures,
dynamic range,
image sidelobes,
image size,
imaging techniques,
likelihood extremization,
maximum likelihood estimation,
scatterers,
sidelobe leakage effects,
threedimensional SAR.
Abstract: 
Threedimensional information content in radar data taken from suitably curved aperture paths is sufficient to allow useful 3D images to be produced by appropriate imaging techniques. The coherent CLEAN algorithm, the IMP algorithm, and maximum likelihood estimation have been used to produce 3D images from data obtained for two such scenarios. The IMP algorithm in conjunction with likelihood extremization produces images free of sidelobe leakage effects found in the CLEAN algorithm. The CLEAN and IMP algorithms find use initiating likelihood extremization on or near its global maximum. Dynamic range of such images appears dependent upon levels at which artifacts appear although valid scatterers are indicated below such levels. Artifacts appear to be a function of the image sidelobes determined by the aperture configuration. Reduction of this problem and methods to increase image size will extend the general usefulness of this technique 
@InProceedings{knaell1996:NonLinearSARTomo,
Title = {{Threedimensional SAR from curvilinear apertures}},
Author = {Knaell, Kenneth},
Booktitle = {Radar Conference, 1996., Proceedings of the 1996 IEEE National},
Pages = {220225},
Url = {http://ieeexplore.ieee.org/iel3/3738/10936/00510684.pdf},
Year = {1996},
Abstract = {Threedimensional information content in radar data taken from suitably curved aperture paths is sufficient to allow useful 3D images to be produced by appropriate imaging techniques. The coherent CLEAN algorithm, the IMP algorithm, and maximum likelihood estimation have been used to produce 3D images from data obtained for two such scenarios. The IMP algorithm in conjunction with likelihood extremization produces images free of sidelobe leakage effects found in the CLEAN algorithm. The CLEAN and IMP algorithms find use initiating likelihood extremization on or near its global maximum. Dynamic range of such images appears dependent upon levels at which artifacts appear although valid scatterers are indicated below such levels. Artifacts appear to be a function of the image sidelobes determined by the aperture configuration. Reduction of this problem and methods to increase image size will extend the general usefulness of this technique},
Keywords = {SAR Processing, NonLinear Flight Path, SAR Tomography, curvilinear SAR, image enhancement, interference suppression, maximum likelihood estimation, radar antennas, radar clutter, radar crosssections, radar imaging, synthetic aperture radar, IMP algorithm, aperture configuration, artifacts, coherent CLEAN algorithm, curvilinear apertures, dynamic range, image sidelobes, image size, imaging techniques, likelihood extremization, maximum likelihood estimation, scatterers, sidelobe leakage effects, threedimensional SAR},
Owner = {ofrey},
Pdf = {../../../docs/knaell1996.pdf},
Timestamp = {2007.11.06}
}

Jung Ah C. Lee,
Orhan Arikan,
and David C. Munson, Jr..
Formulation of a General Imaging Algorithm for HighResolution Synthetic Aperture Radar.
In ICASSP '96, International Conference on Acoustics, Speech, and Signal Processing,
volume 4,
pages 20922095,
May 1996.
Keyword(s): SAR Processing,
Backprojection,
Convolution Backprojection.
Abstract: 
We consider the application of an alternative imaging algorithm to the inversion of stripmapping synthetic aperture radar (SAR) data. The algorithm was originally developed and successfully applied in the area of geophysics to estimate the conductivity distribution from wellbore induction measurements. The SAR measurement relation satisfies the same form of integral equation describing the wellbore problem. By exploiting the form of the measurement kernel, we derive a SAR image formation algorithm involving deconvolutionbackprojection. Unlike correlationbased SAR image formation, our approach is more general, without simplifying assumptions on the range function, and is robust to measurement noise, at the expense of increased computational complexity. Simulation results are presented that demonstrate the effectiveness of the proposed algorithm. 
@InProceedings{JungArikMuns96:Backproj,
Title = {{Formulation of a General Imaging Algorithm for HighResolution Synthetic Aperture Radar}},
Author = {Jung Ah C. Lee and Orhan Arikan and David C. {Munson, Jr.}},
Booktitle = {ICASSP '96, International Conference on Acoustics, Speech, and Signal Processing},
Month = May,
Pages = {20922095},
Volume = {4},
Year = {1996},
Abstract = {We consider the application of an alternative imaging algorithm to the inversion of stripmapping synthetic aperture radar (SAR) data. The algorithm was originally developed and successfully applied in the area of geophysics to estimate the conductivity distribution from wellbore induction measurements. The SAR measurement relation satisfies the same form of integral equation describing the wellbore problem. By exploiting the form of the measurement kernel, we derive a SAR image formation algorithm involving deconvolutionbackprojection. Unlike correlationbased SAR image formation, our approach is more general, without simplifying assumptions on the range function, and is robust to measurement noise, at the expense of increased computational complexity. Simulation results are presented that demonstrate the effectiveness of the proposed algorithm.},
Keywords = {SAR Processing,Backprojection,Convolution Backprojection},
Pdf = {../../../docs/jungArikanMunson96.pdf}
}

F. Lombardini.
Absolute phase retrieval in a threeelement synthetic aperture radar interferometer.
In Radar, 1996. Proceedings., CIE International Conference of,
pages 309312,
October 1996.
@InProceedings{Lombardini1996,
Title = {Absolute phase retrieval in a threeelement synthetic aperture radar interferometer},
Author = {Lombardini, F.},
Booktitle = {Radar, 1996. Proceedings., CIE International Conference of},
Doi = {10.1109/ICR.1996.574449},
Month = oct,
Pages = {309312},
Year = {1996},
Owner = {ofrey}
}

F. Lombardini and P. Lombardo.
Maximum likelihood array SAR interferometry.
In Digital Signal Processing Workshop Proceedings, 1996., IEEE,
pages 358361,
September 1996.
@InProceedings{Lombardini1996a,
Title = {Maximum likelihood array SAR interferometry},
Author = {Lombardini, F. and Lombardo, P.},
Booktitle = {Digital Signal Processing Workshop Proceedings, 1996., IEEE},
Doi = {10.1109/DSPWS.1996.555535},
Month = sep,
Pages = {358361},
Year = {1996},
Owner = {ofrey}
}

John W. McCorkle and Martin Rofheart.
Order N^2 log(N) Backprojector Algorithm for Focusing WideAngle WideBandwidth ArbitraryMotion Synthetic Aperture Radar.
In Gerald S. Ustach, editor,
Radar Sensor Technology,
volume SPIE 2747,
pages 2536,
1996.
Keyword(s): SAR Processing,
BackProjection,
Fast BackProjection,
Quadtree Processing,
TimeDomain BackProjection,
Wideband SAR,
Focusing,
Motion Compensation.
Abstract: 
A new, fast algorithm for synthetic aperture radar (SAR) image formation is introduced. The algorithm is based on a decomposition of the time domain backprojection technique. It inherits the primary advantages of time domain backprojection: simple motion compensation, simple and spatially unconstrained propagation velocity compensation, and localized processing artifacts. The computational savings are achieved by using a divideandconquer strategy of decomposition, and exploiting spatial redundancy in the resulting subproblems. The decomposition results in a quadtree data structure that is readily parallelizable and requires only limited interprocessor communications. For a SAR with N aperture points and an N by N image area, the algorithm is seen to achieve O(N^2 logN) complexity. The algorithm allows a direct trade between processing speed and focused image quality. 
@InProceedings{McCorkle:N2logNBackproj,
Title = {{Order N^2 log(N) Backprojector Algorithm for Focusing WideAngle WideBandwidth ArbitraryMotion Synthetic Aperture Radar}},
Author = {John W. McCorkle and Martin Rofheart},
Booktitle = {Radar Sensor Technology},
Editor = {Gerald S. Ustach},
Pages = {2536},
Url = {http://opac.nebis.ch/ALEPH/2B5BMLRLIMDYIGQHXVPG4ULATX1PC3RPJRTNXXK1NX3B7V8F6F09023/file/startids},
Volume = {SPIE 2747},
Year = {1996},
Abstract = {A new, fast algorithm for synthetic aperture radar (SAR) image formation is introduced. The algorithm is based on a decomposition of the time domain backprojection technique. It inherits the primary advantages of time domain backprojection: simple motion compensation, simple and spatially unconstrained propagation velocity compensation, and localized processing artifacts. The computational savings are achieved by using a divideandconquer strategy of decomposition, and exploiting spatial redundancy in the resulting subproblems. The decomposition results in a quadtree data structure that is readily parallelizable and requires only limited interprocessor communications. For a SAR with N aperture points and an N by N image area, the algorithm is seen to achieve O(N^2 logN) complexity. The algorithm allows a direct trade between processing speed and focused image quality.},
Keywords = {SAR Processing, BackProjection, Fast BackProjection, Quadtree Processing, TimeDomain BackProjection, Wideband SAR, Focusing, Motion Compensation},
Pdf = {../../../docs/McCorkleRofheart96.pdf}
}

B. Walker,
G. Sander,
M. Thompson,
B. Burns,
R. Fellerhoff,
and D. Dubbert.
A highresolution, fourband SAR Testbed with realtime image formation.
In Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International,
volume 3,
May 1996.
@InProceedings{Walker1996,
Title = {A highresolution, fourband SAR Testbed with realtime image formation},
Author = {Walker, B. and Sander, G. and Thompson, M. and Burns, B. and Fellerhoff, R. and Dubbert, D.},
Booktitle = {Geoscience and Remote Sensing Symposium, 1996. IGARSS '96. 'Remote Sensing for a Sustainable Future.', International},
Month = may,
Volume = {3},
Year = {1996},
Owner = {ofrey}
}

Zhu Zhaoda,
Qiu Xiaohui,
and She Zhishun.
Modified Doppler centroid tracking method for phase compensation in ISAR.
In Radar, 1996. Proceedings., CIE International Conference of,
pages 751754,
October 1996.
Keyword(s): ISAR.
@InProceedings{Zhaoda1996,
Title = {Modified Doppler centroid tracking method for phase compensation in ISAR},
Author = {Zhu Zhaoda and Qiu Xiaohui and She Zhishun},
Booktitle = {Radar, 1996. Proceedings., CIE International Conference of},
Doi = {10.1109/ICR.1996.574604},
Month = oct,
Pages = {751754},
Year = {1996},
Keywords = {ISAR},
Owner = {ofrey}
}

Zhaoda Zhu,
Xiaohui Qiu,
and Zhishun She.
ISAR motion compensation using modified Doppler centroid tracking methods.
In Aerospace and Electronics Conference, 1996. NAECON 1996., Proceedings of the IEEE 1996 National,
volume 1,
pages 359363,
May 1996.
Keyword(s): ISAR.
@InProceedings{Zhu1996,
Title = {ISAR motion compensation using modified Doppler centroid tracking methods},
Author = {Zhaoda Zhu and Xiaohui Qiu and Zhishun She},
Booktitle = {Aerospace and Electronics Conference, 1996. NAECON 1996., Proceedings of the IEEE 1996 National},
Doi = {10.1109/NAECON.1996.517674},
Month = may,
Pages = {359363},
Volume = {1},
Year = {1996},
Keywords = {ISAR},
Owner = {ofrey}
}
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Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to
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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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