基于FM广播的无源雷达自适应回波重建系统研究

摘要

Passive radar based on freq uency modulation broadcast is introduced. Because of its high-carrier-frequency and narrow-band,sampling frequency can be reduced greatly using narrowband sampling theorem,which is helpful to real-time signal processing. Moreover,echo signals are interfered seriously by strong direct-path wave. Because Doppler shift is relatively small,frequency spectrums of echo signal and direct-path wave interference overlap seriously. Obviously,classic filter is helpless in this case. Therefore,adaptive echo reconstruction system based on least mean square is designed. Simulation shows that direct-path wave interference has greatly been suppressed and echo signals have successfully been reconstructed,which indicates that the designed system is effective.%介绍了采用调频广播作为外辐射源的无源雷达，因FM广播载频高和带宽窄，采用窄带采样定理可以保证在信号无失真采样的前提下大大降低采样频率，为实时信号处理提供方便。另外，目标回波会受到较强的直达波干扰影响，由于多普勒频移相对较小，目标回波与直达波干扰频谱混叠严重，使用经典滤波器进行直达波干扰抑制十分困难。因此，设计了基于最小均方的自适应回波重建系统，仿真表明，直达波干扰抑制效果明显，目标回波得到较好重建，自适应回波重建系统工作性能良好。