An Aperture Selection Method for ISAR imaging of Ship Targets under Long-Term High Sea States

The motion of a maneuvering ship can be decomposed as the consistent translational motion and oscillation. In high sea conditions, the oscillation of the ship is the main factor causing defocusing, and the ISAR (Inverse Synthetic Aperture Radar) method is usually used for imaging. However, under long synthetic aperture durations, ISAR imaging results can vary significantly across different time intervals. Therefore, this paper proposes an aperture selection method for ISAR imaging of ship targets under long-term high sea states. The proposed method first employs time-frequency analysis for the initial selection, Then, the segment center is determined based on GRFT (Generalized Radon-Fourier Transform) parameter space connectivity analysis and the Doppler bandwidth of sub-aperture ISAR imaging. Next, the data segment length is identified based on the parameter matching accuracy of GRFT. Finally, ISAR imaging is performed on the selected data segment. Simulation show that the proposed algorithm achieves good imaging performance.