说明：  基于频谱细化的线性调频信号的参数估计。首先对中频信号延时相乘然后对产生的序列做FFT，初步算出LFM信号的调频斜率，然后用CHIRP-Z变换精确估计。
(Estimated based on the parameters of the linear FM signal spectrum refinement. First of delay multiplied by the IF signal and then do the FFT on the resulting sequence, initially calculated the slope of the LFM signal FM accurate estimate, and then use the CHIRP-Z transform.)