ISAR Imaging Algorithm of Multiple Targets with Complex Motions Based on the Fractional Tap Length Keystone Transform

Complex motions of targets cause migration through resolution cells which leads to the inverse synthetic aperture radar (ISAR) image blurred and makes difficulties to follow-up work such as identification, recognition, and classification. In this paper, a novel ISAR imaging algorithm based on the fractional tap length keystone transform (FTLKT) is proposed for multiple targets with complex motions. In noncooperation case, different targets behave variously. For phase coupling of different orders, the proposed algorithm first employs FTLKT to achieve decoupling of the frequency and slow time variable, then detection of Doppler peaks is applied for ambiguity resolution of different targets. According to this, focused ISAR images of different targets are obtained. Simulation results demonstrate the validity of the proposed algorithm.