中文说明：
王丰华等提出的相位差分法的实现，主要用于信号处理中提取信号的瞬时频率。注意该方法只适用于单分量信号。另外一个是利用自相关法求瞬时频率。
English Description：
The realization of phase difference method proposed by Wang Fenghua is mainly used to extract instantaneous frequency of signal in signal processing. Note that this method is only applicable to single component signal. The other is to calculate the instantaneous frequency by autocorrelation.