A Novel ISAR Imaging Method Based on Coherent Integration CPF and NUFFT for Maneuvering Target

The azimuth time-varying Doppler frequency, caused by the complex movement of maneuvering target, deteriorates the azimuth focusing quality. Conventional Range-Doppler (RD) imaging algorithm, Wigner-Ville distribution (WVD) imaging algorithm and Radon-Wigner imaging algorithm, due to Poor image quality and inefficient operation and so on, are unfit for ISAR imaging of the complex motion target. To solve these problems, a novel ISAR imaging method based on coherent integration cubic phase function (CPF) for maneuvering target is proposed in the letter. First, the echo data in a range bin after translational compensation are transformed into the time-chirp rate plane via CPF. Then, the auto-terms energy can be coherently integrated in the time-chirp rate distribution plane and can effectively suppress the troublesome cross-term interference and spurious peaks, and then obtain the distribution of the scatter energy in frequency-chirp rate plane. Finally, the azimuth ISAR image can be obtained via a simple maximization projection from the two-dimensional accumulated plot to the azimuth dimension, and the non-uniform fast Fourier transform (NUFFT) is also adopted to reduce the computing complexity. Computer simulation results verify the effectiveness of the proposed method.