HHT(hilbert Huang-transfrom)可以实现同时对信号的时频分析，得到信号的Hilbert时频谱和能量谱，-HHT (hilbert Huang-transfrom) can achieve the same time, the time-frequency analysis, when the signal spectrum and Hilbert energy spectrum

The HHT represents a time-dependent series in a two-dimensional (2-D) time-frequency domain by extracting instan eous frequency components within the signal through an Empirical Mode Decomposition (EMD) process. The analytical background of t

HHT就是先将信号进行经验模态分解（EMD分解），然后将分解后的每个IMF分量进行Hilbert变换，得到信号的时频属性的一种时频分析方法。 -HHT is the first signal empirical mode decomposition (EMD decomposition), then each IMF component decomposition of the Hilbert transform, time-frequency frequency analysis meth

There a lot of time–frequency methods used for studying the time–frequency distribution of the nonlinear and non-stationary signal, such as short time Fourier transform (STFT) (Zhang and Bao, 1998), Wavelet transform (WT) (Hu et al., 2009), S-transfo