【摘要】 机动目标的复杂运动导致散射体回波信号多普勒频率时变,给逆合成孔径雷达(ISAR)成像方位向处理带来困难.而传统的距离-多普勒(RD)成像方法、Wigner-Ville distribution(WVD)瞬时成像方法、Radon-Wigner等成像方法由于成像效果差或运算效率低等因素,不适合复杂运动目标的ISAR实时成像.针对这些问题,本文提出了一种基于相干积累三次相位函数(CPF)的机动目标ISAR成像新方法.首先,把平动补偿后的各距离单元数据,通过CPF变换到时间-调频率平面.然后,利用各散射体自项能量平行于时间轴分布特性,提出一种基于相干积累的交叉项和虚假伪峰抑制方法,进而得到各散射体在频率-调频率平面的高分辨分布特性.最后,通过向频率轴上的投影得到该距离单元目标的方位ISAR图像,并通过引入非均匀快速傅立叶变换(NUFFT)来降低算法计算复杂度.计算机仿真处理结果验证了该方法的有效性.更多还原

【Abstract】 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.更多还原