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 center frequency is calculated by using the power spectrum or amplitude spectrum data.)