Final TerraSAR-X Calibration Results Based on Novel Efficient Methods

Schwerdt, Marco; Bräutigam, Benjamin; Bachmann, Markus; Döring, Björn; Schrank, Dirk; González, Jaime Hueso

doi:10.1109/tgrs.2009.2035308

Cited by 91 publications

(71 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Unlike for the pointing determination using notch-patterns, for antenna pattern verification, the nominal antenna beams and excitation coefficients are applied. The strategy presented here has already been successfully used for the satellites TerraSAR-X [17], TanDEM-X [18] and Sentinel-1A [3].…”

Section: In-flight Antenna Model Verificationmentioning

confidence: 99%

Independent System Calibration of Sentinel-1B

et al. 2017

View full text Add to dashboard Cite

Sentinel-1B is the second of two C-Band Synthetic Aperture Radar (SAR) satellites of the Sentinel-1 mission, launched in April 2016-two years after the launch of the first satellite, Sentinel-1A. In addition to the commissioning of Sentinel-1B executed by the European Space Agency (ESA), an independent system calibration was performed by the German Aerospace Center (DLR) on behalf of ESA. Based on an efficient calibration strategy and the different calibration procedures already developed and applied for Sentinel-1A, extensive measurement campaigns were executed by initializing and aligning DLR's reference targets deployed on the ground. This paper describes the different activities performed by DLR during the Sentinel-1B commissioning phase and presents the results derived from the analysis and the evaluation of a multitude of data takes and measurements.

show abstract

Section: In-flight Antenna Model Verificationmentioning

confidence: 99%

Independent System Calibration of Sentinel-1B

et al. 2017

View full text Add to dashboard Cite

show abstract

“…To the best of our knowledge, no operator of a previous or current space-borne SAR system claims to provide traceable radiometric calibration, and the quoted measurement uncertainties in the respective data product specifications or other publications [5,6,[8][9][10][11] remain questionable. At the moment, a comprehensive uncertainty analysis, preferably in accordance with the ISO Guide to the expression of uncertainty in measurement (GUM) [7], is lacking.…”

Section: Problem Statementmentioning

confidence: 99%

“…An external radiometric calibration campaign results in a pool of data samples (see [5] for an example), one per reference point target ERCS per SAR image. Depending on the research question, the data often needs to be grouped to estimate group-level parameters (for compensation) or to select group-level models (for validation).…”

Section: Hierarchical Modelsmentioning

confidence: 99%

“…Absolute calibration is, for practical reasons and an expected higher calibration quality, executed as an external calibration for space-borne SAR systems [3]. Reference point targets (typically corner reflectors or active radar calibrators [3][4][5][6]) with known radar reflectivities are distributed within an imaged scene, and their backscatters are related to the indications from the SAR system through a proportionality constant, often called calibration factor K. Usually the external calibration is repeated for a number of acquisitions, each using a number of reference point targets, in order to reduce random effects through averaging.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2013

View full text Add to dashboard Cite

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.

show abstract

“…Transponders, or polarimetric active radar calibrators (PARCs), are devices which are used as point targets for the radiometric calibration of space-or airborne synthetic aperture radar (SAR) instruments [2,4,9,21]. Transponders consist of a receiving antenna, a very stable amplifier loop, and a transmit antenna [1,6,13].…”

Section: Introductionmentioning

confidence: 99%

The Three-Transponder Method: A Novel Method for Accurate Transponder RCS Calibration

Döring¹,

Reimann²,

Raab³

et al. 2014

PIER B

View full text Add to dashboard Cite

Abstract-Transponders (also known as polarimetric active radar calibrators or PARCs) are commonly used for radiometric calibration of synthetic aperture radars (SARs). Currently three methods for the determination of a transponder's frequency-dependent radar cross section (RCS) are used in practice. These require either to measure disassembled transponder components, or a separate radiometric measurement standard (like a flat, metallic plate or a corner reflector), leading to additional uncertainty contributions for the calibration result. In this paper, a novel method is introduced which neither requires disassembly nor an additional radiometric reference. Instead, the measurement results can be directly traced back to a realization of the meter, lowering total measurement uncertainties. The method is similar in approach to the well known three-antenna method, but is based on the radar equation instead of Friis transmission formula. The suitability of the method is demonstrated by a measurement campaign for DLR's three new Kalibri C-band transponders, completed by an uncertainty analysis. The method is not universally applicable for all transponder calibrations because (a) three devices are necessary (instead of only one for the known methods), and (b) the transponders must provide certain additional features. Nevertheless, these features have become standard in modern SAR calibration transponder designs. The novel, potentially more accurate three-transponder method is thus a viable alternative for transponder RCS calibration, ultimately contributing to synthetic aperture radars with a reduced radiometric measurement uncertainty.

show abstract

Final TerraSAR-X Calibration Results Based on Novel Efficient Methods

Cited by 91 publications

References 12 publications

Independent System Calibration of Sentinel-1B

Independent System Calibration of Sentinel-1B

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

The Three-Transponder Method: A Novel Method for Accurate Transponder RCS Calibration

Contact Info

Product

Resources

About