Role of the Orbital Tube in Interferometric Spaceborne SAR Missions

IEEE Trans. Geosci. Remote Sensing

González

et al. 2016

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392

232

Sentinel-1 (S-1) has an unparalleled mapping capacity. In interferometric wide swath (IW) mode, three subswaths imaged in the novel Terrain Observation by Progressive Scans (TOPS) SAR mode result in a total swath width of 250 km. S-1 has become the European workhorse for large area mapping and interferometric monitoring at medium resolution. The interferometric processing of TOPS data however requires special consideration of the signal properties, resulting from the ScanSAR-type burst imaging and the antenna beam steering in azimuth. The high Doppler rate in azimuth sets very stringent coregistration requirements, making the use of enhanced spectral diversity (ESD) necessary to obtain the required fine azimuth coregistration accuracy. Other unique aspects of processing IW data, such as azimuth spectral filtering, image resampling, and data deramping and reramping, are reviewed, giving a recipe-like description that enables the user community to use S-1 IW mode repeat-pass SAR data. Interferometric results from S-1A are provided, demonstrating the mapping capacity of the S-1 system and its interferometric suitability for geophysical applications. An interferometric evaluation of a coherent interferometric pair over Salar de Uyuni, Bolivia, is provided, where several aspects related to coregistration, deramping, and synchronization are analyzed. Additionally, a spatiotemporal evaluation of the along-track shifts, which are directly related to the orbital/instrument timing error, measured from the SAR data is shown, which justifies the necessity to refine the azimuth shifts with ESD. The spatial evaluation indicates high stability of the azimuth shifts for several slices of a datatake.

Section: B Burst Synchronization Aspects For Interferometrymentioning

confidence: 99%

“…This state-of-the-art procedure is precisely described in [28] and not detailed here. There are however some interesting aspects to consider regarding the accuracy of the external DEM for the geometric azimuth coregistration in case of squinted acquisitions, which are covered in [22].…”

Section: Coregistrationmentioning

confidence: 99%

Interferometric Processing of Sentinel-1 TOPS Data

Yague-Martinez

IEEE Trans. Geosci. Remote Sensing

González

et al. 2016

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392

232

“…Current spaceborne missions like TerraSAR-X and Sentinel-1 achieve accuracies in the order of 5 ms or better in the burst synchronization, which would lead to a spectral decorrelation of 0.4 Hz for the suggested L-band system, hence having a negligible impact. It should be pointed out that, as discussed in [35], Δ actually varies across the acquisition, according to the properties of the orbital tube. Though this effect is not relevant for a Sentinel-1-like configuration it should be kept in mind, especially for larger orbital tubes and higher frequencies.…”

Section: ) Spectral Decorrelation Due To Burst (Cycle) Synchronizationmentioning

confidence: 98%

“…where = − =− 570 Hz/s for the parameters of TABLE I (at far range). This implies the same synchronization requirement of a ScanSAR acquisition, which is a bit more stringent than in TOPS [35], but which in any case does not pose a challenge. Current spaceborne missions like TerraSAR-X and Sentinel-1 achieve accuracies in the order of 5 ms or better in the burst synchronization, which would lead to a spectral decorrelation of 0.4 Hz for the suggested L-band system, hence having a negligible impact.…”

Section: ) Spectral Decorrelation Due To Burst (Cycle) Synchronizationmentioning

confidence: 99%

Slow Pulse Repetition Interval Variation for High-Resolution Wide-Swath SAR Imaging

Almeida

Younis

IEEE Trans. Geosci. Remote Sensing

et al. 2021

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In the context of spaceborne synthetic aperture radar (SAR) imaging, high resolution and wide swath are inherently conflicting requirements. These may however be simultaneously satisfied by advanced imaging modes with multichannel architectures in elevation and/or azimuth. The paper elaborates on a new mode based on multiple elevation beams and a simple PRI variation scheme which allows highresolution wide-swath imaging. It is shown to use the illumination time more efficiently than ScanSAR and yet to be simpler than staggered SAR. Good SAR imaging performance is achieved with a rather compact antenna design. The proposed imaging mode is suitable for spaceborne SAR systems with planar and reflector antennas. In order to improve the imaging performance, a reflector antenna architecture with a multichannel feed in both elevation and azimuth is considered.

“…In order to achieve such a stringent coregistration requirement we propose to use a geometric coregistration approach based on an external DEM and accurate orbit information. The required DEM accuracy will depend on the magnitude of the crossing orbit angle between image pairs, which depends on the selected orbital tube [9]. For the STEREOID mission, current available DEMs, e.g., SRTM or TanDEM-X, suffice to meet the required coregistration accuracy.…”

Section: Insar Processingmentioning

confidence: 99%

Bistatic SAR Image Formation and Interferometric Processing for the Stereoid Earth Explorer 10 Candidate Mission

IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium

Pinheiro

Rodríguez-Cassolà

et al. 2019

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This paper addresses the aspects of image formation and interferometric processing in the frame of the STEREOID Earth Explorer 10 candidate mission. In particular, the large along-track baseline configuration (approx. 250 km), which results in a high Doppler centroid, will be addressed in terms of bistatic SAR image formation and interferometric processing. The proposed focusing algorithm is validated with pointtarget simulations, while the interferometric investigations are performed using raw data generated with a bistatic end-to-end simulator.