非合作无源探测中的假设检验弱目标检测方法

在非合作无源探测系统中,弱目标回波不仅会受到强直达波、强多径的干扰,还会受到强目标的掩盖干扰,因此很难对其进行有效检测。为了解决这一问题,提出了一种基于多择复合假设检验的弱目标检测方法。首先将接收信号投影到多径干扰的正交补子空间内,以消除强直达波和强多径干扰,然后将目标检测看作一个多择复合假设检验问题,建立了与之相应的基本框架模型,利用最大后验估计方法对目标时延、多普勒频移及信号幅度等参数进行估计,构造检验统计量,设置相应的门限,根据假设检验结果,逐个消除强目标干扰从而达到检测弱目标的目的。仿真结果表明,本方法可以有效抑制强直达波、强多径及强目标干扰,有效检测出弱目标,且虚警率低。

Weak target detection method based on hypothesis test theory in non-cooperative passive detection

Due to the interference from strong direct signal, multipath signals and echoes from strong sources, it is difficult to detect weak targets in non-cooperative passive detection system. In order to solve this problem, a method for weak target detection based on multiple composite hypothesis test theory is proposed. To begin with, projections of the received signal in a subspace orthogonal to both the strong, direct and multipath disturbance achieve the cancellation of strong, direct signal and multipath signal. Target detection is treated as multiple composite test problem and the corresponding theory frame is built up. Unknown parameters such as delay, Doppler frequency and signal amplitude are estimated using maximum a posteriori criterion for the achievement of test detection statistics. The required threshold is derived and interference from strong targets is degraded and subtractedstep by step according to the results of hypothesis test decision. Finally, simulation results demonstrate that the proposed approach can conduct the cancellation of strong direct signal, multipath and echoes from strong sources and detect very weak target at low false alarm rate.