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Mittermayer J.,German Aerospace Center | Younis M.,German Aerospace Center | Metzig R.,German Aerospace Center | Wollstadt S.,German Aerospace Center | And 2 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2010

This paper presents results from the synthetic aperture radar (SAR) system performance characterization, optimization, and verification as carried out during the TerraSAR-X commissioning phase. Starting from the acquisition geometry and instrument performance, fundamental acquisition parameters such as elevation beam definition, range timing, receiving gain, and block adaptive quantization setting are presented. The verification of the key performance parameters-ambiguities, impulse-response function, noise, and radiometric resolution-is discussed. ScanSAR and Spotlight particularities are described. © 2009 IEEE.

Alparone L.,University of Florence | Argenti F.,University of Florence | Bianchi T.,University of Florence | Abbate M.,University of Cassino and Southern Lazio | And 3 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2010

In this work, maximum a posteriori (MAP) despeckling, implemented in the multiresolution domain defined by the undecimated discrete wavelet transform (UDWT), will carried out on very high resolution (VHR) SAR images and compared with earlier multiresolution approaches developed by the authors. The MAP solution in UDWT domain has been specialized to SAR imagery. Every UDWT subband is segmented into statistically homogeneous segments and one generalized Gaussian (GG) PDF (variance and shape factor) is estimated for each segment. This solution allows to effectively handle scene heterogeneity as imaged by the VHR SAR system. Segmentation exploits a Tree Structured Markov Random Field (TSMRF), which is a low complexity MRF segmentation that allows the estimation of the number of segments and the segmentation itself to be carried out at same time. Experiments performed on a single-look VHR X-band SAR images demonstrate that the segmented approach is effective whenever the classical circular Gaussian model of complex reflectivity may no longer hold. © 2010 IEEE.

Meta A.,MetaSensing | Mittermayer J.,German Aerospace Center | Prats P.,German Aerospace Center | Scheiber R.,German Aerospace Center | Steinbrecher U.,German Aerospace Center
IEEE Transactions on Geoscience and Remote Sensing | Year: 2010

This paper reports about the performed investigations for the implementation of the wide-swath TOPS (Terrain Observation by Progressive Scan) imaging mode with TerraSAR-X (TSX). The TOPS mode overcomes the limitations imposed by the ScanSAR mode by steering the antenna along track during the acquisition of a burst. In this way, all targets are illuminated with the complete azimuth antenna pattern, and, thus, scalloping is circumvented, and an azimuth dependence of signal-to-noise ratio and distributed target ambiguity ratio (DTAR) is avoided. However, the use of electronically steered antennas leads to a quantization of the steering law and a nonideal pattern for squinted angles (grating lobes and main lobe reduction). The former provokes spurious peaks, while the latter introduces slight scalloping and DTAR deterioration. These effects are analyzed and quantified for TSX, and a TOPS system design approach is presented. Next, the requirements concerning interferometry are investigated. Finally, several results are shown with the TSX data, including a comparison between the TOPS and the ScanSAR modes and the reporting of the first TOPS interferometric results. © 2009 IEEE.

Prats P.,German Aerospace Center | Scheiber R.,German Aerospace Center | Mittermayer J.,German Aerospace Center | Meta A.,MetaSensing | Moreira A.,German Aerospace Center
IEEE Transactions on Geoscience and Remote Sensing | Year: 2010

This paper presents an efficient phase preserving processor for the focusing of data acquired in sliding spotlight and Terrain Observation by Progressive Scans (TOPS) imaging modes. They share in common a linear variation of the Doppler centroid along the azimuth dimension, which is due to a steering of the antenna (either mechanically or electronically) throughout the data take. Existing approaches for the azimuth processing can become inefficient due to the additional processing to overcome the folding in the focused domain. In this paper, a new azimuth scaling approach is presented to perform the azimuth processing, whose kernel is exactly the same for sliding spotlight and TOPS modes. The possibility to use the proposed approach to process data acquired in the ScanSAR mode, as well as a discussion concerning staring spotlight, is also included. Simulations with point targets and real data acquired by TerraSAR-X in sliding spotlight and TOPS modes are used to validate the developed algorithm. © 2009 IEEE.

Coccia A.,University of Perugia | Lukic N.,MetaSensing | Meta A.,MetaSensing
GIM International | Year: 2013

The SnowSAR is a radar sensor which was commissioned to support the European Space Agency's (ESA) Cold Region Hydrology High-Resolution Observatory (CoReH2O) mission candidate Earth Explorer 7 satellite. Together with international partners, the idea of CoReH2O is to research the properties of snow and ice by employing a space-borne twin-frequency (X and Ku bands) polarimetric Synthetic Aperture Radar (SAR) instrument. The SnowSAR radar sensor has proven its snow and ice-monitoring capabilities both in three of the countries which have a share of the land in the Arctic Circle, namely Finland, Canada and US (Alaska), and outside of the Arctic Circle (in Austria). Snow pack structure and morphology can differ quite widely from region to region, depending on different terrain types and on the background composition. The first two SnowSAR measurement campaigns in the winters of 2011 and 2012 were conducted in collaboration with the Finnish Meteorological Institute in the Lappish region of Finland, which is an example of the typical Eurasian taiga belt.

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