例求X(s)= 的变换 S(S+a) 解:X(S)=s+=+(+四+ a,s_、Ss=0-a2 S(S+a) 2 S(S+a) s+a 3 ds s s=-a X(S)= 2 sS+a s+al X(2 102有 (Z-e)2 Z e Zd-e -aTe)z+e(aTo-1+e) a(z-1)(Z-e)22 2 0 0 1 ( ) 1 1 1 1 2 1 1 1 1 ds d 3 2 1 ( ) 1 2 1 0 ( ) 1 1 ( ) ( ) 1 ( 1)( ) Z[(1 - ) ( 1 )] X(Z) ( ) X(S) a a ( ) a ( ) 0 0 0 0 0 0 2 2 0 0 0 2 2 2 2 2 2 2 3 2 1 2 2 a T a T a T a T a T Ze Z Z e a T Ze Z a Z a a a a a s s a S S a s a a a s S S a s a a s a a s a S S a a Z Z e e aT e Z e aT e s s a s a s a s X s a T a T a T − − − − − − − =− =− + = + + + + − − − + − + = = − − + − + = − = = − = + = − = = = = + + − − − 例.求X(s)= 的Z变换。 : ( ) 2 ( ) 1 解 求 X S = S S +a 的Z变换 解: