抽样频率转换在数字下变频中的应用

数字下变频技术是软件无线电中的关键技术之一。从信号中去除高频信息，降低抽样频率而不导致频谱混叠的过程称之为抽取。若信号不进行滤波就抽取，信号将出现混叠，那么其关键问题就是抽取前的滤波。现以软件无线电的基本知识为基础，分析了单级和多级抽样频率转换，并进行了比较。

Application of sampling frequency transform in digital variable frequency

Digital variable frequency is a key technology of soft radio.Filtering the high frequency part of the signal and reducing the sampling frequency,which does not produce the aliasing,is called sampling.If the signals are sampled before the filtering,the signals' spectrum will be aliasing.The filtering technology is a key issue before the sampling.On the basis of the soft radio,this paper analyzes the sampling frequency transform for single series and the series,and compares them.