实现stft变换，输出时域图，频域图，能量谱等信号分析图。-Stft achieve transformation, the output time domain diagram, frequency domain, the energy spectrum and other signal analysis chart.

时频分析的希尔伯特-黄变换方法适用于非线性非平稳的信号分析。-Time-frequency analysis of Hilbert- Huang Transform method is applicable to non-linear non-stationary signal analysis.

短时傅里叶变换是一种基于窗函数的变换，短窗能够提供较好的时域解析度，长窗能够提供较好的频域解析度。-Short-time Fourier transform is a transform window function based on the short window in the time domain can provide better resolution, the long window can provide better resolution in the frequency d