Synthetic aperture radar calibration using reference reflectors

Gray, Alistair; Vachon, P.W.; Livingstone, C.E.; Lukowski, T.I.

doi:10.1109/36.54363

Cited by 166 publications

(82 citation statements)

References 11 publications

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“…A widely used approach to verify the geolocation accuracy of SAR is based on artificial point-like targets deployed on ground [16]. Their positions in focused SAR images are measured and compared to the expected values that are derived from the knowledge of the target's on-ground coordinates and the determination of the satellite position at closest approach.…”

Section: Verification Of the Geolocation Accuracy Of Sarmentioning

confidence: 99%

Measurements on the Absolute 2-D and 3-D Localization Accuracy of TerraSAR-X

Balss¹,

Gisinger²,

Eineder³

2018

Remote Sensing

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Abstract:The German TerraSAR-X radar satellites TSX-1 and TDX-1 are well-regarded for their unprecedented geolocation accuracy. However, to access their full potential, Synthetic Aperture Radar (SAR)-based location measurements have to be carefully corrected for effects that are well-known in the area of geodesy but were previously often neglected in the area of SAR, such as wave propagation and Earth dynamics. Our measurements indicate that in this way, when SAR is handled as a geodetic measurement instrument, absolute localization accuracy at better than centimeter level with respect to a given geodetic reference frame is obtained in 2-D and, when using stereo SAR techniques, also in 3-D. The TerraSAR-X measurement results presented in this study are based on a network of three globally distributed geodetic observatories. Each is equipped with one or two trihedral corner reflectors with accurately (<5 mm) known reference coordinates, used as a reference for the verification of the SAR measured coordinates. Because these observatories are located in distant parts of the world, they give us evidence on the worldwide reproducibility of the obtained results. In this paper we report the achieved results of measurements performed over 6 1/2 years (from July 2011 to January 2018) and refer to some first new application areas for geodetic SAR.

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Section: Verification Of the Geolocation Accuracy Of Sarmentioning

confidence: 99%

Measurements on the Absolute 2-D and 3-D Localization Accuracy of TerraSAR-X

Balss¹,

Gisinger²,

Eineder³

2018

Remote Sensing

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“…With the peak method, the target power is described by the pixel with the peak power (complex pixel amplitude squared) whereas with the integral method, the target power results as the sum of pixel powers over a relevant region around the target. It was shown that the integral method is advantageous as it leads to accurate results even if the image is not perfectly focused [21]. Thus the integral method was chosen for this analysis.…”

Section: Power Estimation For Point Targets From Sar Imagesmentioning

confidence: 99%

Hierarchical Bayesian Data Analysis in Radiometric SAR System Calibration: A Case Study on Transponder Calibration with RADARSAT-2 Data

et al. 2013

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A synthetic aperture radar (SAR) system requires external absolute calibration so that radiometric measurements can be exploited in numerous scientific and commercial applications. Besides estimating a calibration factor, metrological standards also demand the derivation of a respective calibration uncertainty. This uncertainty is currently not systematically determined. Here for the first time it is proposed to use hierarchical modeling and Bayesian statistics as a consistent method for handling and analyzing the hierarchical data typically acquired during external calibration campaigns. Through the use of Markov chain Monte Carlo simulations, a joint posterior probability can be conveniently derived from measurement data despite the necessary grouping of data samples. The applicability of the method is demonstrated through a case study: The radar reflectivity of DLR's new C-band Kalibri transponder is derived through a series of RADARSAT-2 acquisitions and a comparison with reference point targets (corner reflectors). The systematic derivation of calibration uncertainties is seen as an important step toward traceable radiometric calibration of synthetic aperture radars.

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“…The radar brightness in turn equals sigma-naught divided by sine of the local incidence angle [22]. The above definition of radiometric calibration is related to the well-known integral method, [23]. The covariance matrix data are calibrated such that the radar cross section of a point target is the sum of the pixel values in the mainlobe times the pixel size of 25 m , and the sigmanaught value of a distributed target is the ensemble average of the pixels.…”

Section: B Calibrationmentioning

confidence: 99%

EMISAR: an absolutely calibrated polarimetric L- and C-band SAR

Christensen

Skou

Dall

et al. 1998

IEEE Trans. Geosci. Remote Sensing

102

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Abstract-EMISAR is a high-resolution (2 2 2 2 2 m), fully polarimetric, dual-frequency (L-and C-band) synthetic aperture radar (SAR) system designed for remote-sensing applications. The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry. Thermal control and several calibration loops have been built into the system to ensure system stability and absolute calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key to most of the current applications. Recent interferometric enhancements are important for many scientific applications.

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Synthetic aperture radar calibration using reference reflectors

Cited by 166 publications

References 11 publications

Measurements on the Absolute 2-D and 3-D Localization Accuracy of TerraSAR-X

Measurements on the Absolute 2-D and 3-D Localization Accuracy of TerraSAR-X

Hierarchical Bayesian Data Analysis in Radiometric SAR System Calibration: A Case Study on Transponder Calibration with RADARSAT-2 Data

EMISAR: an absolutely calibrated polarimetric L- and C-band SAR

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