说明：  频谱分析技术是研究周期性现象中最为常用的一种统计分析方法，其主要是通过对一复合的波系进行数据变换，将其分解成若干振幅和相位不同的简谐波，并找出其中振幅最大的波，即该复合波中的主要频率。频谱分析的方法较多，其中最常用的是快速傅立叶变换法(FFT)
(spectrum analysis techniques to study the cyclical phenomenon most commonly used a statistical analysis method, its principal is a composite of the wave data transformation, its decomposition into a number of different amplitude and phase of the harmonic, and finding the biggest wave amplitude, which is the compound of the main wave frequency. Spectrum analysis method more, the most common of which is a fast Fourier transform (FFT))