A NOVEL HIGH-ORDER IMAGE FORMATION ALGORITHM FOR GNSS-BASED BISTATIC SAR

Global Navigation Satellite System (GNSS)-based bistatic Synthetic Aperture Radar (SAR) recently plays a more and more significant role in remote sensing applications for its low-cost, flexibility and real-time global coverage capability. In this paper, a novel high-order imaging algorithm is presented for GNSS-based bistatic SAR. Firstly, the modified equivalent squint range model (MESRM) is introduced to describe range history of the GNSS-based bistatic SAR, and the accuracy of the MESRM is analysed. Secondly, a high-order image formation algorithm based on the MESRM is derived, where the range cell migration (RCM) of the echo signal is corrected by two-step range cell migration correction (TSRCMC), and the azimuth-variance of the echo signal is solved by azimuth block hybrid correlation. Finally, simulation and experiment are performed to validate the presented algorithm.