Experimental SAR Processors for Bistatic Concepts Considering Companion Satellites

This paper presents prototype processors developed by sarmap, in the framework of investigations fostered by European Space Agency (ESA) for possible future bistatic SAR missions, characterized by innovative tandem geometries obtained through the companion satellite (CS) concept. Such missions would offer a wealth of new possibilities for the extraction of geophysical information by methods such as tomography and bistatic radiometry. Nevertheless, in consideration of the experimental nature of the envisaged tandem geometries, studies are required to pave the way for proper design of ground segment processors, especially concerning focusing of raw data collections.Bistatic CS orbital configurations considered for the project here discussed are those of SAOCOM-CS proposal. The processors that have been developed are structured into two components: focusing of bistatic raw data, and continuous tomography. The focusing module has been designed according to a rigorous time-domain approach in order to serve as a test processor and also to handle some of the unconventional geometries of SAOCOM-CS, which lead to large squint angles and, as such, pose questions about applicability of efficient spectral approaches. On the other side, a beamforming approach has been considered for tomography because of the benefits provided by this method over Fourier techniques in presence of irregular and sparse baseline sampling. In order to test the focuser, a simulator of point-target raw echoes has been implemented. Tomography, on the other hand, has been applied to airborne L-band images from ESA BIOSAR 2008 campaign.