基于周期FRFT的LFMCW信号检测与参数估计

线性调频连续波(LFMCW)含有多个线性调频信号分量,具有低截获概率特性,雷达情报侦察系统对此类信号的检测与参数估计十分困难.针对这个问题,首先分析了LFMCW的分数阶Fourier变换(FRFT),通过对FRFT核函数的周期调制,定义了周期分数阶Fourier变换(PFRFT),推导了PFRFT和FRFT的关系.然后分析了LFMCW的PFRFT,提出了一种基于PFRFT的未知LFMCW检测和参数估计方法,并对其检测和估计性能进行了理论分析.最后仿真验证了该方法的有效性和合理性.相比FRFT,PFRFT通过对LFMCW的周期性积累提高了信噪比,适合处理具有周期调制的类似LFMCW信号.

Periodic FRFT-based LFMCW signal detection and estimation

Linear frequency-modulated continuous wave （LFMCW） signals have low probability interception （LPI） characteristics, and contain multicomponent LFM signals. The detection and estimation of LFMCW signals is a difficult problem for radar intelligence and reconnaissance systems. In addressing this problem, first the fractional Fourier transform （FRFT） of the LFMCW signal is analyzed. By periodic modulating of the FRFT kernel function, the periodic fractional Fourier transform （PFRFT） is defined, and the relationship between the PFRFT and FRFT is derived. By analyzing the PFRFT of the LFMCW, a novel method based on the PFRFT to detect and estimate an unknown LFMCW is presented. The detection and estimation performance are also discussed. Finally, simulation verifies its effectiveness and rationality. Compared with the FRFT, PFRFT increases the LFMCW SNR with periodic accumulation, and fits a periodic modulated signal to the LFMCW.