无源雷达多站定位LFM弱信号检测

无源雷达多站TDOA定位时,要求多站同时截获目标雷达的辐射信号,并且为满足定位精度而要求一定的基线长度,然而现代机载雷达采用超低副瓣、降低平均功率等许多低截获措施,使得双接收站配置一般不会被机载雷达主瓣同时覆盖,致使一个接收站处在发射天线的主波束内时,另一接收站处在副瓣或零点位置,因此双接收站之间接收的信号强度相差悬殊,至少差20dB的主副瓣比。为此,利用相关接收理论分析了在雷达主瓣方向的侦察接收机截获的强信号,确定脉冲重复周期、脉内调制等基本信息。并利用该信息及信号协同在雷达副瓣方向的侦收机的微弱信号进行相关接收,推导出独立于截获信号结构的混合积模型,从而使双通道侦收机的信号处理可以直接借鉴传统雷达的相参与非相参等信号积累方法。通过雷达实测信号构建双路信号的仿真验证表明该方法的理论可行性和工程可用性。

Detection and Parameters Estimation of LFM Weak Signal in Multi-Static Passive Radar

It is desired for multi-static passive radar to intercept target radar signals simultaneously during the process of location which utilizes the time difference of arrival（TDOA）. However, many LPI（（low probability of interception） techniques are adopted by airborne radar in practice such as low side lobe method and narrow beam technique. As a result, receivers will not locate in the coverage of major lobe simultaneously. One is covered by the main beam while others locate in the side lobe of the antenna. Therefore the difference of signals＇ strength between these receivers will be more than 20 dB. The strong signal intercepted by the receiver in the main beam is analyzed by auto-correlation theory, and signal＇s periodicity is estimated. Then we take it as replica of the side lobe signal to define the model of mixing product. Furthermore, mixing product signal which has no relations to do with the modulation of signal is deduced. Finally, an example of real data processing is given, which validates its effectiveness in application.