正弦信号抽样序列的周期性与伪调制性

Periodicity and Fake Modulation of Sinusoidal Signal Sampling Sequence

在满足抽样定理条件前提下,当抽样频率处于某个范围内时,正弦信号抽样序列的包络与抽样序列的周期性与原始信号相比产生了很大的变化,抽样序列的包络出现了不应有的调制———伪调制,这种调制干扰了对原始信号包络的分析和提取。文中首先研究了抽样序列的周期性规律,然后从理论上分析了伪调制性产生的原因,推导出了伪调制的普适公式,得到了伪调制的调制规律和调制规律的周期性,最后得出了消除伪调制两个基本的方法。

When sinusoidal signal is sampled and sampling frequency that accords with sampling theorem belongs to a fixed scope, periodicity and envelope of sampling sequence is different from original signal, unpredictable modulation is produced——fake modulation. Analysis and pick-up of envelope is disturbed by this modulation. Firstly the rule of periodicity is studied, then the phenomenon of fake modulation is proved, the formulas of the fake modulation are given, modulating rule of fake modulation and periodicity of modulating rule are presented .Finally, two basic measures to avoid fake modulation are elicited.