一、直接计算DFT的问题及改进途径 N点有限长序列x(n) DFT: X()=DFT[x(m】-∑x(m)WRv(k) n=0 IDFT: Dr7T2g”Rw一、直接计算DFT的问题及改进途径 1 0 : ( ) [ ( )] ( ) ( ) N nk N N n DFT X k DFT x n x n W R k 1 0 : 1 ( ) [ ( )] ( ) ( ) N nk N N k IDFT x n IDFT X k X k W R n N N x n 点有限长序列 ( )