For sampling signal x()=x()∑6(t-m7)=∑x(m7)6(t-n7) the laplace transform [x、()=x()e"t S=+j2 ∑x(nT)J。(-nl"t if s=jQ2, a=QT ∑x(n7)e"=X(e)=X(e0) 1= an z-transform of discrete-=2x[n-n=X() 令zQ@e7=e T time signal n=-0o0 e 9 1111 For sampling signal， ( ) ( ) st c n x nT t nT e dt   − − = −   ( )  − =− =  sTn c n x nT e [ ] ( ) ( ) st s s x t x t e dt  − − = L  sT ( j T) z e e +  令 @ = [ ] ( ) n n x n z X z  − =− = =  z-transform of discrete￾time signal the Laplace transform s c c ( ) ( ) ( ) ( ) ( ) n n x t x t t nT x nT t nT     =− =− = − = −  ( ) ST = X e if s j , =   = T = x n[ ] j re  = s j = +   − j n  e ( ) j X e ; T r e  =