EH4

代码说明：

  计算两个信号的功率谱密度，通过两个信号的谱相关系数决定频点是否参与叠加计算，以控制功率谱密度质量。(Calculation of the two signal power spectral density, spectral signals through two related factors involved in the decision whether or not frequency superposition calculation, in order to control the quality of the power spectral density.)