基于幅度和相位联合的ATI动目标检测新方法

分析了影响SAR-ATI动目标检测干涉相位图中点幅度和相位分布的因素--包括雷达噪 声、杂波能量、地面RCS起伏以及成像时的旁瓣等.针对SAR-ATI检测时虚警概率过高问题, 基于幅度门限和相位门限联合动目标检测处理,提出了一种改进方法:首先对SAR每一个 通道的图像域中相位被污染的点作一次关于能量梯度的预滤波,在滤除了干涉相位图中相位 失效的点之后,根据雷达的固有噪声及干涉相位分布图,在概率意义下设定滤波门限进行 自适应幅度滤波;最后采用相位门限进行检测处理,有效降低了虚警概率;同时给出一个 由干涉相位图中统计量拟合出的动目标检测曲线经验公式,能够明显降低在低杂噪比条件下 的虚警概率.仿真结果验证了此方法的有效性.

New method of ATI moving targets indication based on amplitude and phase thresholds

The factors,which influence the distribution of the amplitude and phase of the points in the phase interferogram of SAR-ATI moving targets indication,including radar-noise,scatter energy,background uneven RCS and the side lobe of image pixels were analyzed.To resolve the problem of the high false alarm rate in SAR-ATI,an improved method was proposed based on the MTI of the joint amplitude-phase threshold.Firstly,the points with polluted phase in the image of every channel were pre-filtered.Secondly,after eliminating the points with invalidated phase,the adaptive amplitude filtering was processed with the threshold set by the probability,according to the radar-noise and the phase interferogram.In the end,the detection with the phase threshold method was performed to reduce the false alarm rate effectively.An empirical formula derived from the statistic fitted curves in the phase interferogram was presented to reduce the false alarm rate in the low CNR condition evidently.The computer simulation demonstrates this method.