x(0 x1(0=X(0 x1( X1(1)=X(2) x(1) N2点 x, (2) DFT x(2) X1(2)=X(4) x1(3) (3) X1(3)=X(6) Wx(0) X2(0=X(1) W x2( x(5) X2(1)=X(3) N2点 W x2(2) DFT x(6) X2(2)X(5) X2(3)=X(7)x1(0) x1(1) -1 x1(2) x1(3) -1 x2(0) x2(1) -1 x2(2) x2(3) -1 N/2点DFT N/2点DFT x(0) x(7) x(1) x(2) x(3) x(4) x(5) x(6) X1(0)=X(0) X2(0)=X(1) X1(1)=X(2) X1(2)=X(4) X1(3)=X(6) X2(1)=X(3) X2(2)=X(5) X2(3)=X(7) 1 WN0 WN2 WN3 WN