3 Fourier Series Representation of Periodic Signals (2)Discrete time LTI system yIn]=H(zzn hnI y=*小=∑xn一 ∑=k]="∑ "H(=) H()=∑hkF system function3 Fourier Series Representation of Periodic Signals (2) Discrete time LTI system h[n] x[n]=zn y[n]=H(z)zn ( ) [ ] [ ] [ ] [ ]* [ ] [ ] [ ] ( ) z H z z h k z z h k y n x n h n x n k h k n k n k k n k k = = = = = −    + =− − + =− − + =− k k H z h k z − + =− ( ) =  [ ] ( system function )