非平稳信号与周期功率谱

Nonstationary Signals and Cyclic Spectral Density

首先引入了周期相关和周期功率谱（简称周期谱）的概念，并把它们用于振幅调制（ＡＭ）和正交振幅调制（ＱＡＭ）信号的时间平均功率谱的推导。得到了精确的功率谱公式，适合于基带调制信号是非平稳的情况。假设基带信号平稳，则公式可以简化为一般通信教科书中的常见形式。

Cyclic correlation and cyclic power spectral density (cyclic spectrum) are discussed in this paper, followed by their application in the computation of timeaveraged power spectral density for both AM and QAM signals. Therefore, some precise formulas are deduced, which are suitable for nonstationary baseband modulating signals. When the baseband modulating signals are stationary, the formulas reduce to the familiar form in general textbooks.