TerraSAR-X Antenna Calibration and Monitoring Based on a Precise Antenna Model

Bachmann, Markus; Schwerdt, Marco; Bräutigam, Benjamin

doi:10.1109/tgrs.2009.2033934

Cited by 33 publications

(29 citation statements)

References 11 publications

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“…The achievable accuracy, predicted by simulations in the range of 5-20 millidegrees, on the base of a single site with 100k PSs is partly confirmed by results or real data. Such accuracy compares with that achieved from the pattern-notch method in [5].…”

Section: Discussionmentioning

confidence: 64%

“…The resulting accuracy, plotted on the left, shows a degradation from 10 to 20 millidegrees in the two noisy cases. Such accuracies compare with the 7 millidegrees achieved by the method proposed [5], where a pattern with a sharp notch in the middle range was generated and then measured by a rain forest scene. …”

Section: B Roll-angle Error Accuracymentioning

confidence: 59%

“…We assume that the pth target in the nth image is affected by a gain variation in elevation G n (p, Δϑ n ), which is due to the contribution of the range spread loss and the antenna two-way pattern. We assume that this elevation-dependent gain is completely known, usually from internal calibration [5]- [8], but for an error in elevation angle Δϑ n that may result from an attitude offset. We furthermore assume that the nominal elevation-dependent gain G n (p, 0) is normalized to unitary.…”

Section: Ps Modelmentioning

confidence: 99%

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Long-Term Relative Radiometric Calibration and Antenna Pointing Estimation by Natural Targets

Guarnieri

Tebaldini

Giudici

et al. 2013

IEEE Trans. Geosci. Remote Sensing

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In this paper, we revise the relative radiometric calibration of synthetic-aperture-radar stacks which exploits natural persistent scatterers (PSs). We introduce a new model to estimate a slight error in the sensor pointing in elevation and a new coherent method that makes use of phases evaluated by averaging the complex data on the local window. We show that the proposed approach outperforms the conventional one, as it is mostly insensitive to the "differential" biasing that affects the noncoherent permanent scatterer calibration (PScal). Results from processing COnstellation of small Satellites for the Mediterranean basin Observation (COSMO)-SkyMed and European Remote Sensing (ERS) satellites stacks are presented.Index Terms-Inverse problems, radar cross section, radar signal analysis, synthetic aperture radar (SAR).

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Section: Discussionmentioning

confidence: 64%

Section: B Roll-angle Error Accuracymentioning

confidence: 59%

Section: Ps Modelmentioning

confidence: 99%

See 1 more Smart Citation

Long-Term Relative Radiometric Calibration and Antenna Pointing Estimation by Natural Targets

Guarnieri

Tebaldini

Giudici

et al. 2013

IEEE Trans. Geosci. Remote Sensing

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“…After compensating for deterministic behavior of these targets, like a known incidence angle dependency, variations of SAR data can be attributed to changes in the antenna gain. Dedicated antenna patterns like the one from a mono-pulse or notch beams provide a characteristic steep gain drop into a certain (predictable) radiation direction which can be detected and analyzed in a reliable way [17] to determine a potential discrepancy between predicted and actual antenna pointing.…”

Section: Antenna Pointing Determination In Elevation For Spaceborne Smentioning

confidence: 99%

Precise Antenna Pointing Determination in Elevation for Spaceborne SAR Systems Using Coherent Pattern Differences

et al. 2019

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The precise determination of the SAR (synthetic aperture radar) antenna pointing is an essential task initially performed during the commissioning phase of a spaceborne SAR system and is permanently monitored during the whole mission life-time. Besides a correct illumination of the scene during data acquisition, antenna pointing is required for proper compensation of the radiation pattern for radiometric correction during SAR data processing. The Amazon rainforest is a well-established target area for antenna pointing estimation in elevation as proven by many past and current SAR missions. Several new SAR systems are now proposed which are using long wavelengths, i.e., L- and P-bands, which will be implemented using reflector-based antenna systems. These reflectors have, in contrast to planar phased array antennas, no completely rigid connection to the satellite body and, hence, a more volatile antenna pointing. Due to the huge dimensions of such reflector antennas required for the envisaged long wavelengths and the finite stiffness of the boom, the antenna pointing may change significantly along the orbit. Such variation cannot be tracked using the common Amazon rainforest approach only, as this measurement opportunity exists only at two positions along the orbit (ascending and descending). Here, the performance of an alternative technique is presented which mitigates the influence of the underlying SAR scene by employing two coherent SAR datasets acquired simultaneously with different antenna patterns. This allows the use of amplitude and phase information for pointing estimation. No assumption upon the homogeneity of the underlying scene is required and, hence, pointing estimation becomes feasible at nearly any point along the orbit. This paper outlines the technique, describes simulation results and presents outcomes from first experimental acquisitions performed with the TerraSAR-X satellite.

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“…This LTSM has been ensuring a consistent product quality for more than ten years. The success of this performance is based on the innovative design and precise manufacturing of the satellite systems [8,9] on the one hand and on the other on innovative methods, accurate reference targets and the strategy for calibrating and monitoring TSX and TDX over lifetime [5,[10][11][12][13][14][15]. The radiometric performance over lifetime of both systems is analyzed in three steps:…”

Section: Introductionmentioning

confidence: 99%

Radiometric Performance of the TerraSAR-X Mission over More Than Ten Years of Operation

et al. 2018

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The TerraSAR-X mission, based on two satellites, has produced SAR data products of high quality for a number of scientific and commercial applications for more than ten years. To guarantee the stability and the reliability of these highly accurate SAR data products, both systems were first accurately calibrated during their respective commissioning phases and have been permanently monitored since then. Based on a short description of the methods applied, this paper focuses on the radiometric performance including the gain and phase properties of the transmit/receiver modules, the antenna pattern checked by evaluating scenes acquired over uniformly distributed targets and the radiometric stability derived from permanently deployed point targets. The outcome demonstrates the remarkable performance of both systems since their respective launch.

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TerraSAR-X Antenna Calibration and Monitoring Based on a Precise Antenna Model

Cited by 33 publications

References 11 publications

Long-Term Relative Radiometric Calibration and Antenna Pointing Estimation by Natural Targets

Long-Term Relative Radiometric Calibration and Antenna Pointing Estimation by Natural Targets

Precise Antenna Pointing Determination in Elevation for Spaceborne SAR Systems Using Coherent Pattern Differences

Radiometric Performance of the TerraSAR-X Mission over More Than Ten Years of Operation

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