FRFT域LFM信号的调频率分辨率与相位差的关系

Relationship between chirp-rate resolution of LFM signals and phase difference in FRFT domain

相位差是影响信号分辨的一个重要因素。当采样率足够高时,研究在分数阶傅里叶变换域两个线性调频(linear frequency modulation,LFM)信号的相位差与调频率分辨率的约束关系。通过建立调频率的分辨模型,推导出在两个LFM信号可分辨范围内相位差的上界和下界,只有当相位差处于上界和下界之间时,两个LFM信号才可以分辨。仿真结果表明,分辨率的理论值与实际值之间偏差较小,基本吻合。

Phase difference between signals effects deeply on signal resolution. In iractional Pourmr transIorm （FRFT） domain, the relationship between phase difference and chirp-rate resolution of two linear frequency modulalion （LFM） signals at high oversampling rate is investigated. By establishing a resolution model of chirp tale, the curves of upper bound and lower bound of phase difference is calcul.ated when two LFM signals are distinguished. Only when phase difference is located at between the upper bound and the lower bound, can the two LFM signals be distinguished. Simulation results show the deviation of resolution is so small that theoretical values of resolution are consistent basically with actual values.