空中目标探测系统信号处理增益分析

针对利用全球导航卫星反射信号(GNSS-R)进行空中目标探测时,信号微弱无法可靠接收的问题,该文提出了一种计算信号处理增益的方法。通过合理设置信号处理算法参数,保证了对微弱信号的后续处理。首先对GNSS-R信号接收链路进行了分析,计算得到了当目标的雷达散射截面(RCS)变化时对应的目标回波功率范围;然后对空中目标上升、平飞和下降三种飞行状态双基地雷达系统几何模型进行了研究,给出了3种飞行状态下对应的有效探测时间,为接收机后续相干/非相干累加算法的处理时间提供阈值限制;最后在阈值范围内,选定合适相关时间,分析了经过相干/非相干累加处理后的反射信号输出信噪比范围。结果表明:在有效探测时间的限制下,相关处理时间取0.6s时,处理后的信噪比在10dB左右,满足一般码跟踪环所需的门限要求,可以保证接收机后续数据处理的顺利进行。

The analysis of signal processing gain in the air target detection system

According to the fact that the weak signals can not be effectively received when using GNSS-R for air target detection,this paper presented a method of calculating signal processing gain.By setting the parameters of the signal processing algorithm properly,to ensure the subsequent processing of the weak signals.This paper made analysis of GPS signals link performance first,and calculated the range of the corresponding target echo power when the RCS varies.And then,this paper made analysis of geometric models in bistatic radar system based on three kinds of flight status,namely parallel flying,down flying and up flying,and calculated the corresponding effective detection time providing a threshold for the processing time needed by the coherent/noncoherent accumulation algorithm.At last,this paper selected the best correlation time within the scope of threshold value,and then made analysis of the output signalto-noise ratio range of the reflected signals after using coherent/noncoherent accumulation algorithm.The results showed that under the limit of the effective detection time,when the correlation time was 0.6 s,the output signal-to-noise ratio was around 10 dB which satisfied the general threshold requirement of code tracking loop,and ensured the subsequent data processing in the receiver.