2D spatial‐variant phase errors compensation for ISAR imagery based on contrast maximisation

Abstract

Range and azimuth spatial‐variant phase errors are usually presented in high‐resolution inverse synthetic aperture radar imagery as the manoeuvring motion of the observed targets. It could not be effectively compensated by the traditional autofocus algorithms. A new method is proposed for 2D spatial‐variant phase errors compensation based on contrast maximisation. First, a novel phase error parametrical signal model is established. Then, image contrast is introduced as a cost function, and an iterative, modified gradient‐based method is used to solve a maximal contrast optimisation problem. The proposed method has a good convergence within a few iterations. The public data provided by the Naval Research Laboratory is utilised to confirm the effectiveness and superiorities of the proposed method.