A Modified NLCS Algorithm for High-Speed Bistatic Forward-Looking SAR Focusing with Spaceborne Illuminator

The coupling and spatial variation of range azimuth parameters is the biggest challenge for bistatic forward-looking SAR (BFSAR) imaging. In contrast with monostatic translational invariant (TI-BSAR), cell migration (RCM), Doppler high-speed (HS-BFSAR) have two-dimensional characteristics, which makes it difficult to obtain images satisfactory global focusing. Firstly, based on configuration spaceborne illuminator receiving platform, accurate range-Doppler domain expression echo signal derived in this paper. Secondly, using analytical expression, a nonlinear chirp scaling (NLCS) proposed equalize RCM equivalent frequency modulation (FM) rate so that they can be uniformly processed domain. Next, processing, method decomposes contribution transmitter receiver, respectively. Then, an NLCS used eliminate FM rate. Finally, range-dependent filter constructed achieve compression. Simulation results validate efficiency effectiveness algorithm.