Phase-preserving SAR processing for interferometrical applications: results on SIR-C/X-SAR data

This paper presents new results related to high-precision geometric and radiometric processing of synthetic-aperture radar (SAR) data by means of a SAR simulator, and introduces many issues related to phase­ preservation of the processor, a crucial requirement for SAR interferometric processing. The main aspects of the computer code which simulates end-to-end spacebome SAR systems, including dynamical aspects and sensor and terrain characteristics, are presented. The system impulse response derived from the simulator, necessary to focus the raw data, is validated by analyzing real multi­ polarization radar data from the recent 1994 SIR-C/X-SAR mission, gathered over the Italian calibration supersite which was instrumented with active and passive point targets. Concepts and requirements on processor phase fidelity are presented. A number of phase­ preservation tests on the simulator show phase purity and suitability for interferometric product generation. The single-look complex (SLC) multi-polarization images generated by the simulation procedure are compared with the standard SLC product provided by the Jet Propulsion Laboratory (JPL) through the analysis of the impulse response function. The geometric (range and azimuth spatial resolutions) and radiometric (integrated and peak sidelobe ratios) parameters, evaluated in both images on three focused active calibrators, show good performance of the simulator and satisfactory image quality. Tests on the statistics of the phase difference in two simulated homogeneous targets validate the use of our simulator as a raw interferometric SAR data generator.