Validating a spaceborne SAR simulator by using SIR-C/X-SAR data

High-resolution and accuracy applications of spaceborne Synthetic Aperture Radar (SAR) images, such as topographic mapping, require precision geometric and radiometric processing of raw data. In the last years the authors have been developing computer code to simulate spaceborne SARs. This program includes dynamical aspects and sensor and terrain characteristics. This paper deals with the validation of the simulator as a tool to obtain the SAR impulse response necessary to precision focusing of raw data. To this end the SIR-C raw and ancillary data are adopted. In particular, the Space Shuttle orbit and attitude data are used as input of the simulator to compute the time-domain two-dimensional echo from a bright point target embedded in an absorbing background. By using as reference scatterer the geographical coordinates of an Active Radar Calibrator (ARC) deployed on a test area, it is possible to focus the relative raw data, by means of a two-dimensional correlation. After a description of the procedure necessary to adopt the available ancillary data, the compressed image is generated and compared to the single-look complex image provided by the JPL. The point target range and azimuth resolutions and integrated and peak sidelobe ratios are computed in both images, considering as input three focused ARCs. Finally, several plots and tables are shown, demonstrating quantitatively the simulator performance.