基于匹配傅里叶变换的舰船目标成像算法

A method of ISAR ship imaging based on match Fourier transform

为解决逆合成孔径雷达(ISAR)对非合作、机动目标成像时的散焦问题,提出利用瞬时多普勒参数估计补偿相位的成像方法.分析舰船目标的回波特性及其偏航、俯仰、侧摆等转动分量引起的多普勒非线性变化,将回波近似为噪声和杂波背景下的多分量线性调频信号.比较二阶、二步两种匹配傅里叶变换的多普勒参数估计精度.蒙特卡罗实验验证,二步匹配傅里叶变换均具有更好的多普勒分辨力,估计误差较小.利用匹配傅里叶变换估计多普勒频率完成瞬时成像的方法,去除了传统算法中的严重散焦现象,提高了聚焦性能,可获得舰船目标在观测时间内的姿态变化.仿真实验及实测结果验证了该方法的有效性.

Range instantaneous Doppler（RID） algorithm in inve rse synthetic aperture radar （ISAR） imaging with compensation was developed to solve the problem of defocusing for noncooper ative maneuvering targets. The echo characteristics of ship tar get and nonlinear Dopp[er shifts caused by the motion of yaw, pitch and roll were analyzed, and echo was approximated to multicomponents chirp signal under noise and clutters back ground. Doppler parameter estimation accuracies of second order and twostep match Fourier transforms （MFT） were compared. Monte Carlo simulation shows that twostep MFT has fine Doppler resolution with smaller estimation error. Compared with traditional imaging algorithm, the proposed algorithm im proves focusing performance while eliminating the phenomenon of serious defocusing, and motion attitude is obtained at selected observing interval. Simulation and measured results verify its ef fectiveness.