1.引言 Vxa (t) x(n)=x(nT.n=0,±1,±2 X"(e°) 截断 x(n),0≤n≤N-1-)X(e/)- 取样、截断 x'(n) X(k)=(e0)2 k=0.1……,N-1 x(n).0≤n≤N-1 DET DES X(k),0≤k≤Nx (t)  a x(n)= x (nT), n = 0,1,2, a △ ( ) j X e 截断 x(n),0  n  N −1 ( ) j X e ? 取样、截断 k N j k X k X e    ( ) ( ) 2 = = △ k = 0,1,  ,N −1 x (n) ? x(n),0  n  N −1 DFT DFS X (k),0  k  N ? 1.引言