Luca Marotti

TOPS Interferometry With TerraSAR-X

This paper presents results on SAR interferometry for data acquired in the Terrain Observation by Progressive Scans (TOPS) imaging mode. The rationale to retrieve accurate interferometric products in this mode is expounded, emphasizing the critical step of coregistration. Due to the particularities of the TOPS mode, a high Doppler centroid is present at burst edges, demanding a very high azimuth coregistration performance. A coregistration accuracy of around one tenth of a pixel, as it is usually recommended for stripmap interferometric data, could result in large undesired azimuth phase ramps in each TOPS burst. This paper presents two approaches based on the spectral diversity technique to precisely estimate this coregistration offset with the required accuracy and evaluates their performance. The effect of squint at burst edges in terms of an undesired impulse response shift during focusing and the impact on the interferometric coregistration performance is also addressed. Repeat-pass TOPS data acquired experimentally by TerraSAR-X are used to validate the proposed approaches.

First Bistatic Spaceborne SAR Experiments With TanDEM-X

TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) is a high-resolution interferometric mission with the main goal of providing a global and unprecedentedly accurate digital elevation model of the Earth surface by means of single-pass X-band synthetic aperture radar (SAR) interferometry. Despite its usual quasi-monostatic configuration, TanDEM-X is the first genuinely bistatic SAR system in space. During its monostatic commissioning phase, the system has been mainly operated in pursuit monostatic mode. However, some pioneering bistatic SAR experiments with both satellites commanded in nonnominal modes have been conducted with the main purpose of validating the performance of both space and ground segments in very demanding scenarios. In particular, this letter reports about the first bistatic acquisition and the first single-pass interferometric (mono-/bistatic) acquisition with TanDEM-X, addressing their innovative aspects and focusing on the analysis of the experimental results. Even in the absence of essential synchronization and calibration information, bistatic images and interferograms with similar quality to pursuit monostatic have been obtained.

Taxi: A versatile processing chain for experimental TanDEM-X product evaluation

TanDEM-X is a high-resolution interferometric radar mission with the main goal of providing a global digital elevation model (DEM) of the Earth surface by means of single-pass X-band SAR interferometry. It is, moreover, the first genuinely bistatic spaceborne SAR mission, and, independently of its usual quasi-monostatic configuration, includes many of the peculiarities of bistatic SAR. An experimental, versatile, and flexible interferometric chain has been developed at DLR Microwaves and Radar Institute for the scientific exploitation of TanDEM-X data acquired in non-standard configurations. The paper describes the structure of the processing chain and focusses on some essential aspects of its bistatic part. Some experimental results performed with TerraSAR-X demonstrate the flexibility of the implemented processor.

Interferometric sea ice mapping with TanDEM-X: First experiments

In summer 2010 during the commissioning phase of TanDEM-X, the TerraSAR-X/TanDEM-X constellation was operated in the pursuit monostatic mode allowing along-track interferometric measurements with very short time separation of only 2.6 sec. This paper presents first evaluations of data acquired on arctic sea ice scenarios and investigates the potentials for the mapping of ice sheet dynamics with respect to rotation and translation with this unique constellation. Due to the larger coverage, the data analysis is focused on interferometric ScanSAR data.

Investigations on TOPS interferometry with TerraSAR-X

This paper presents results on SAR interferometry with the so-called TOPSmode. The rationale to retrieve accurate interferometric products with such a mode is expounded, emphasizing the critical step of coregistering the pairs. Due to the particularities of the TOPS mode, a high Doppler-centroid is present at burst edges, demanding very high azimuth coregistration performance. A coregistration accuracy of one tenth of a pixel, as it is usually recommended with interferometric applications, will result in a large undesired azimuth phase ramp in the TOPS mode, above all at X-band. This paper presents two approaches based on the spectral diversity technique to estimate this offset with the required accuracy. Experimental results with repeat-pass TerraSAR-X data are shown to validate the proposed approach.

Recent advances in Polarimetric SAR Interferometry for forest parameter estimation

Polarimetric SAR Interferometry (Pol-InSAR) is a radar remote sensing technique that, based on the coherent combination of SAR interferometry and radar polarimetry, provides sensitivity to the vertical distribution of different scattering processes and makes the inversion of forest structure parameters possible. In this paper we present the main scientific results achieved in actual airborne campaigns, discuss the potential and limitations of the different inversion scenarios (based on different frequencies, temporal and spatial baselines) and draw the conclusions.

First bistatic spaceborne SAR experiments with TanDEM-X

TanDEM-X is a high-resolution interferometric mission with the main goal of providing a global and unprecedentedly accurate digital elevation model (DEM) of the Earth surface by means of single-pass X-band SAR interferometry. Despite its usual quasi-monostatic configuration, TanDEM-X is the first genuinely bistatic SAR system in space. During its monostatic commissioning phase, the system has been mainly operated in pursuit monostatic mode. However, some pioneering bistatic SAR experiments with both satellites commanded in non-nominal modes have been conducted with the main purpose of testing the performance of both space and ground segments in very demanding scenarios. In particular, this paper reports about the first bistatic acquisition and the first single-pass interferometric (mono/bistatic) acquisition with TanDEM-X. Even in the absence of essential synchronisation and calibration information, bistatic images and interferogramswith similar quality to pursuit monostatic have been obtained.

Analysis of the temporal behavior of coherent scatterers (CSs) in ALOS PalSAR data

Coherent scatterers (CSs) are scatterers detected by using spectral correlation properties and characterized by a deterministic scattering behavior. In this paper we investigate, for the first time, the temporal behavior of CSs using quad-pol data acquired by ALOS/PalSAR. In this sense, we can evaluate the stability of the deterministic scattering nature of individual scatterers.