对载波调制信号欠采样问题的研究

Research on Carrier Wave Modulate Signal's Non-Nyquist Sampling

对AM信号进行峰值采样可以直接获得基带信号的信息,对PSK信号进行变频采样可以降低其载波频率.文中给出了一个比较容易实现的峰值采样定理,这种采样方式适用于包络与基带信号相对应的AM和DSB信号;指出变频采样是周期信号欠采样的一种特例,它仅适用于波形在分段时间内具有周期性的PSK和FSK信号,而且用于FSK信号时采样频率的选择受到较多的限制;对变频采样给出了一种选择采样频率的有效方法,还指出了变频采样与模拟信号变频之间的区别.

By peak value sampling the information of baseband signal can be obtained from an AM signal directly.By frequency conversion sampling the carrier wave's frequency of a PSK signal can be cut down.This paper presents a specific peak value sampling theorem,which can be applied to AM and DSB signal easily.It points out that frequency conversion sampling is a special case of periodic signal's nonNyquist sampling,and can be applied to PSK and FSK signal only.A theorem about choosing the sampling frequency of frequency conversion sampling has been proposed.The difference between frequency conversion sampling and analogue signal's frequency conversion has been shown.