同理: X,(k)=X(k)+WNoX(k k=0 N X2(k+)=X5(k)-WM2X6(k) 4 其中: Xs(k)=DFTIx= dFtix,(2D)] l=0.1.N/4-1 x6()=DFTx()=DF7x2(2/+1) 统一系数:W2→>W2 5 / 2 6 2 5 / 2 6 ( ) ( ) ( ) ( ) ( ) ( ) 4 k N k N X k X k W X k N X k X k W X k 0,1,..., 1 4 N k 同理: 其中: 5 5 2 X (k) DFT[x (l)] DFT[x (2l)] 6 6 2 X (k) DFT[x (l)] DFT[x (2l 1)] l 0,1,...,N / 4 1 2 / 2 k k 统一系数:WN WN