Design Considerations of PRF for Optimizing GMTI Performance in Azimuth Multichannel SAR Systems With HRWS Imaging Capability

Abstract

Using multichannel in azimuth to suppress the Doppler ambiguities allows for high-resolution wide-swath (HRWS) synthetic aperture radar (SAR) imaging, thus overcoming the minimum antenna area constraint of the conventional space-borne SAR. If the degrees of freedom in azimuth are used for the clutter suppression, the ground moving target indication (GMTI) can be achieved. Therefore, a space-borne multichannel SAR system for GMTI has the potential to offer HRWS imaging capability to some extent. However, here, the GMTI performance may suffer from the Doppler ambiguity caused by the undersampling. This paper focuses on the analysis of the influence of pulse repetition frequency (PRF) on GMTI performance in Doppler ambiguity. The multichannel signal models of the clutter and the moving target with Doppler ambiguity are derived in complex image domain. Considering the Doppler ambiguity and the multichannel spatial ambiguity, the influence of PRF on the output signal-to-clutter-plus-noise ratio after adaptive clutter suppression and the signal-to-noise ratio loss after SAR imaging is discussed. Accordingly, the design considerations of PRF for optimizing GMTI performance in multichannel SAR systems with HRWS imaging capability are given, along with a simulation example. Finally, the real-data experiments verify the theoretical investigations.