Spaceborne SAR Radiometric Calibration and Characterization Using a Radar Target Simulator

The distinction of distributed terrain targets surveyed with Synthetic Aperture Radar (SAR) by their brightness difference in the image essentially depends on a speckle noise probability distribution. SAR radiometric resolution experimental verification in terms of a homogeneous target backscatter distinction would imply the necessity of a radar test site containing a set of uniform clutter patterns having successively increasing backscatter coefficients. A way of overriding this problem using an active transponder with digital signal processing as a test facility for the calibrated homogeneous target echo simulation is introduced. The proposed method enables SAR radiometric resolution, sensitivity and dynamic range direct measurements, and provides some extra features for external radiometric calibration. The Differential Radiocontrast method is introduced as the basis of test image automated analysis.