例: x(n)= u(n 右边序列 3 X()=∑2z2|= 0 jIm=] R 3 R Re[-]10 例： ( ) 3 1 (1) x(n) u n n       = 右边序列 3 1 3 1 1 1 3 1 ( ) 1 0 1 − = −  =      = −  = −  z z z X z z n n 3 1 1 Rx = 3 1  z  3 1 1 Rx = 3 1 j Im[z] Re[z]