基于信号杂波噪声比的认知雷达扩展目标探测波形设计

Cognitive radar waveform design for extended target detection based on signal-to-clutter-and-noise ratio

针对认知雷达在杂波环境下探测扩展目标时,回波信号的信号杂波噪声比(SCNR)较低的问题,提出了一种基于SCNR认知雷达发射波形优化设计方法。首先,不同于以往的点目标模型,通过建立扩展目标探测模型,得到认知雷达回波信号杂波噪声比(SCNR)与发射信号能量谱密度(ESD)间的关系;其次,根据最大SCNR准则推导出发射信号ESD的全局最优解;最后,为了得到有实际意义的时域信号,采用相位调制的方式,结合最小均方误差(MMSE)和迭代算法将最优ESD合成满足雷达发射要求的恒幅时域信号。仿真实验中,该方法所得时域合成信号幅度为1,在匹配滤波器输出端的SCNR为19.133 d B,仅小于理想值0.005 d B。结果表明,所得到的时域波形不仅能够满足恒幅要求,而且能使接收机输出端的SCNR接近理想值,提高了扩展目标探测性能。

Focusing on the issue that the Signal-to-Clutter-and-Noise Ratio （SCNR） of echo signal is low when cognitive radar detects extended target, a waveform design method based on SCNR was proposed. Firstly, the relation between the SCNR of cognitive radar echo signal and the Energy Spectral Density （ESD） of transmitted signal, was gotten by establishing extended target detection model other than previous point target model; secondly, according to the maximum SCNR criterion, the global optimal solution of the transmitted signal ESD was deduced; finally, in order to get a meaningful time-domain signal, ESD was synthesized to be a constant amplitude based on phase-modulation after combining with the Minimum Mean- Square Error （MMSE） and iterative algorithm, which met the emission requirements of radar. In the simulation, the amplitude of time-domain synthesized signal is uniform, and its SCNR at the output of the matched filter is 19. 133 dB, only 0.005 dB less than the ideal value. The results show that not only can the time-domain waveform meet the requirement of constant amplitude, but also the SCNR obtained at receiver output can achieve the best approximation to the ideal value, and it improves the performance of the extended target detection.