首先对采样信号进行傅里叶变换，计算出功率谱或幅值谱，然后用功率谱或者幅值谱的数据，计算每一个中心频率的带宽内数据的平均值。(Firstly, Fourier transform is applied to the sampled signal to calculate the power spectrum or amplitude spectrum, and then the average value of the data within the bandwidth of each cente