Clutter statistical analysis for high resolution SAR data

The ONERA RAMSES system (Radar Aeroporte Multi-spectral d´Etude des Signatures) is a flexible SAR system in constant evolution developed mainly as a test bench for new technologies and to provide specific data for TDRI (Target Detection, Recognition and Identification) algorithm evaluation. It is flown on a Transall C160 platform operated by the CEV (Centre d´Essais en Vol). Recently, the system was upgraded to include a very high resolution mode in X, Ku and Ka bands. The resolution cell is then only a few wavelength wide and the usual hypothesis underlying the speckle phenomena, i.e., a large number of scatterers per resolution cell, is not verified. This work presents the analysis made on the clutter statistical behavior and contrasts the change of behavior observed when shifting from medium resolution to high resolution to very high resolution. It is based on actual radar data acquired with the RAMSES radar system. A new parameter identifying the largest spatial resolution for which the natural surface can no longer be considered homogeneous (in a speckle based criteria) is proposed. This parameter characterizes the scale of the contributing scatterers.