3.0 Introduction Fourier transform plays a key role in analyzing and representing discrete-time signals and systems,but does not converge for all signals. -品=24 1-ae jo 1-ae -ae Continuous systems:Laplace transform is a generalization of the Fourier transform. Discrete systems z-transform,which is a generalization of DTFT,converges for a broader class of signals 33 3.0 Introduction ◆Fourier transform plays a key role in analyzing and representing discrete-time signals and systems, but does not converge for all signals. ◆Continuous systems: Laplace transform is a generalization of the Fourier transform. ◆Discrete systems : z-transform, which is a generalization of DTFT, converges for a broader class of signals. xn a un n = a 1 DTFT 0 1 1 j ae −  = −   n n jwn a u n e  =− −  ！ 1 ( ) 1 j j ae ae    − − − = −