无源双基地雷达广义相参检测性能分析

Generalized Coherent Detection Performance Analysis for Passive Bistatic Radar

研究了外辐射源发射信号的带宽未能准确已知时,无源双基地机会探测系统的广义相参检测性能。首先构建了无源双基地雷达系统中双通道接收信号的模型,并给出了无源双基地雷达恒虚警检测统计量的构造思路,然后推导得到了基于互模糊函数检测统计量的特征函数、概率密度函数与检测概率及虚警概率的解析表达式,并详细分析了不同系统输入参数条件下的相参检测性能。检测性能的分析表明,当目标回波信噪比大于-20dB且直达波信噪比大于5dB时,就有可能检测到目标,而且采样信号带宽失配较小时的检测性能与带宽匹配时的检测性能差别较小,相比于带宽匹配时的检测性能,采样信号带宽失配系数小于2时检测概率的恶化幅度均小于0.1。

Cross ambiguity processing is commonly used for target detection in passive bistatic radar system.However,its theoretical detection performance on passive bistatic radar is rarely encountered in previous published papers.This paper addresses the theoretical problem of detecting the presence of a target echo in passive bistatic radar when the bandwidths of opportunity illuminators are unknown.Analytical expressions are obtained for the characteristic function and probability density function （PDF） of normalized cross ambiguity function （NCAF） when the data samples in the target surveillance and reference channels are contaminated by narrowband uncorrelated white Gaussian noises.The closed form of detection probability and false alarm probability for NCAF are derived.They are used to determine which cell in the ambiguity surface exceeds a preset threshold.Results are presented in the form of curves showing the values of input SNRs required to achieve a specified detection probability for different system parameters.The detection performance shows that target signal can be detected when SNR in target surveillance channel is large than-20 dB and SNR in direct-path channel is large than 5 dB.Furthermore,compared to the detection performance in matched sampling case,the detection probability will be decreased about 0.1 if the mismatch coefficient of sampling is less than 2.