Low-Flying Moving Target Detection and Imaging Algorithm of Spaceborne SAR Based on Two-Dimensional Velocity Search

Using spaceborne SAR to detect low-flying moving targets is a difficult problem in the application field of SAR. The existence of ground clutter and sea clutter, mutual interference in the detection of slow and high-velocity targets, azimuth Doppler folding of moving targets, range cell migration and other problems lead to serious defocusing of high-speed moving targets, which is difficult to effectively detect in SAR image. Ultimately, these lead to the difficulty of motion parameter estimation and imaging. Therefore, when the traditional SAR imaging algorithm is used to image the moving target of the spaceborne SAR, the target is usually in a defocused state, which leads to the degradation of the detection performance. In this paper, combined with the BP algorithm, a spaceborne SAR moving target detection algorithm based on two-dimensional velocity (range velocity and azimuth velocity) search is designed to match the Doppler parameters. After realizing the ergodic focusing of the moving target at a uniform speed, target detection is followed. Then the detection probability and imaging quality of the moving target can be improved by comparing the associated amplitude values at different search speeds. The simulation results verify the feasibility and effectiveness of the algorithm.