Compressed sensing-based multi-aperture focusing of spaceborne transmitter/stationary receiver bistatic SAR data

In this paper, we introduce a compressive sensing-based approach for increasing bistatic synthetic aperture radar imaging quality in the context of multi-aperture acquisition. The analyzed data is recorded over an opportunistic bistatic setup including a stationary ground based receiver (COBIS) and Sentinel 1 C-band transmitter. Since the terrain observation by progressive scans mode is operated, the receiver is able to record synchronization pulses and echoed signals from the scene during many apertures. Hence, it is possible to improve the azimuth resolution by exploiting the multi-aperture data. Obviously, the recorded data is not contiguous and a naive integration of the chopped azimuth phase history would generate undesired grating lobes. The proposed processing scheme exploits the natural sparsity characterizing the illuminated scene. Therefore, a matching pursuit compressive sensing algorithm is employed for filling the “gaps” occurring in Doppler spectrum. The sparsifying basis/dictionary is constructed using the synthetic generated azimuth chirp. The obtained results show a significant improvement of the azimuth resolution along with dramatic attenuation of the side-lobes.