Moving Target Trajectory Reconstruction Based on the LM Algorithm in WasSAR System

Wide-angle staring synthetic aperture radar ground moving target indication (WasSAR-GMTI) has garnered attention due to its capability to monitor a stationary area over an extended period and its ability to track moving targets. Recently, the research on moving target trajectory reconstruction has also raised interest. However, the low positioning accuracy and impractical assumption of the traditional method make it hardly a practical application. We propose a novel precise trajectory reconstruction of a moving target in this article. First, we segment the echo into subapertures, after clutter rejection and radial velocity estimation, quasi-maximum likelihood (QML) is applied to estimate the polynomial phase signal (PPS) parameters of the phase history. Then, the Levenberg-Marquardt (LM) algorithm is applied to decouple the motion parameters. Based on the motion parameters, the coarse trajectory can be reconstructed. After that, the envelope history of the moving target is extracted. Modeling the motion trajectory of the moving target in segments and estimating the trajectory of each segment using the corrected envelope history and coarse trajectory. Finally, after processing all segments, the precise trajectory of the moving target is obtained. The effectiveness and practicability of the proposed algorithm were demonstrated by the processing results of experimental wide-angle staring synthetic aperture radar (WasSAR) data.