FFT算法的基本原理是把长序列的DFT逐次分解为较短序列的DFT。按照抽取方式的不同可分为DIT-FFT（按时间抽取）和DIF-FFT（按频率抽取）算法。按照蝶形运算的构成不同可分为基2、基4、基8以及任意因子（2n,n为大于1的整数），基2、基4算法较为常用。-FFT algorithm is the basic principle of DFT successive long sequence is broken down into shorter sequences of DFT. In accordance with the different extraction methods can be divided into the DIT-FFT (time taken) and the DIF-FFT (according to the frequency of extraction) algorithm. In accordance with the composition of different butterfly operations can be divided into base 2, base 4, base 8, as well as arbitrary factor (2n, n is an integer greater than 1), radix-2, Radix-4 algorithm is more commonly used.