Moving target imaging of a dual-channel ISAL with binary phase shift keying signals and large squint angles.

Abstract

A dual-channel inverse synthetic aperture ladar imaging experimental system based on wide-pulse binary phase coded signals and its moving target imaging are introduced. The analysis, simulation, and experimental data processing results of binary phase coded signal Doppler compensation and pulse compression are included. The method of motion phase error estimation based on interferometric processing and the imaging method with small computation in the case of large squint angles are proposed, and the simulation results are presented. The effectiveness of the imaging method is verified by experimental data processing. Doppler frequency curves are estimated based on time-frequency analysis of echo signals, and the coarse compensation of motion phase error is realized. According to the interferometric phase and coherence coefficient of dual-channel echo signals' time-frequency analysis, the coherence of the dual-channel echo signals is checked, and along-track interferometry can be applied to the precise compensation. The stable interferometric phase and increased coherence coefficient of actual dual-channel data imaging results indicate the effectiveness of the motion phase error compensation method proposed. Considering characteristics of inverse synthetic aperture ladar (ISAL) imaging, after dividing echo signals into multiple sub-apertures, range-Doppler algorithm and sub-aperture stitching are adopted, the stitched image is corrected geometrically through Stolt transformation, and the computation is reduced.