FFT滤波误差分析  

Study on FFT Filtering Error

作　　者：杨君[1,2] 吕镜清[2,3] 

机构地区：[1]装备指挥技术学院航天测控工程研究中心,北京101416 [2]信息综合控制国家重点实验室,四川成都610036 [3]中国西南电子设备研究所,四川成都610036

出　　处：《通信技术》2010年第6期235-237,240,共4页Communications Technology

摘　　要：针对工程中FFT存在滤波误差的问题对FFT的滤波原理进行了推导,分析指出了FFT运算与复调制滤波器组滤波运算之间存在的差异,推导出了误差项,并对该误差项造成的相频响应非线性和通带波纹增大进行了仿真分析;对该频率响应误差造成的滤波性能下降进行了仿真验证;针对误差形成原理给出了消除误差的方法;最后分析指出了FFT滤波存在固有的相位超前现象,并根据其产生的原因给出了有效应对措施。In the light of FFT filtering error,the FFT filtering theory is studied,the frequency response differencies between FFT and complex modulated filter bank are given,the error term is deduced,and the nonlinear phase-frequency response error and the pass band ripple increase caused by the error term are analyzed.The decline of filtering performance caused by the frequency response error is simulated and validated.Based on error forming theory,the methods to completely eliminate the error are presented.Finally,the phenomenon of phase advance in FFT filtering is discussed,and the effective method to solve this problem is presented.

关 键 词：快速傅里叶变换 复调制滤波器组 频率响应 群延时 

分 类 号：TN713[电子电信—电路与系统]