基于最大熵法和遗传算法的SMSP干扰对抗方法

SMSP jamming countermeasure method based on maximum entropy method and genetic algorithm

线性调频(LFM)信号是现代雷达常用的发射信号,可以有效提高雷达的检测性能,然而频谱弥散(SMSP)干扰应用于主瓣自卫式干扰时,干扰信号强度远大于目标回波信号,能够对目标回波信号形成遮盖,是一种有效对抗LFM信号的干扰样式。利用干扰信号与目标回波信号时频特征的不同,通过广义S变换(GST)凸显时频特征差异。运用最大熵法和遗传算法(GA)求取时频滤波器的分割阈值。通过构造的时频滤波器达到干扰抑制的目的。仿真结果表明:当干信比(JSR)大于10 dB、信噪比(SNR)大于0 dB时,所提方法具有较好的干扰抑制效果,其中最大信干噪比(SJNR)增益接近25 dB。

Linear frequency modulation(LFM)signal is a commonly used transmission signal of modern radar,which can effectively improve the detection performance of radar.However,when smeared spectrum(SMSP)jamming is applied to the main lobe self-defense,the intensity of the jamming signal is much higher than the target echo signal,and it can cover the target echo signal,which is an effective jamming pattern against LFM signal.In this paper,the difference in time-frequency characteristics of the jamming signal and the target echo signal is used to highlight the difference in time-frequency characteristics through the generalized S transform(GST),and then the maximum entropy method and genetic algorithm(GA)are used to obtain the segmentation threshold of the time-frequency filter.The purpose of jamming suppression is achieved through the constructed time-frequency filter.The simulation results show that when the jamming-to-signal ratio(JSR)is greater than 10 dB and the signal-to-noise ratio(SNR)is greater than 0 dB,it has a better jamming suppression effect,and the maximum signal-to-jamming-plus-noise ratio(SJNR)gain is close to 25 dB.