The correlation method and FFT method of the power spectrum estimation could not completely reflect the concept of the power spectrum of the non-stationary random signals because of data truncation.

对于非平稳随机信号的功率谱分析，采用自相关函数傅里叶变换和直接傅里叶变换分析时，由于存在数据截断，二者从概念上都不能很好地反映随机信号的功率谱。

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