1.2.1 Convolution /96 Convolution is used to describe linear time-invariant (LTI)systems,which are completely characterized by their unit-sample response h(n). y(n)=x(n)h(n)=>x(k)h(n-k) k=-0 x (n) y(n) h(n) Finite impulse response(FIR) Infinite impulse response (IIR) Causal system if h(n)=0 for n<0. 2021年2月 72021年2月 7 1.2.1 Convolution  Convolution is used to describe linear time-invariant (LTI) systems, which are completely characterized by their unit-sample response h(n).  Finite impulse response (FIR)  Infinite impulse response (IIR)  Causal system if h(n)=0 for n<0.       k y(n) x(n)*h(n) x(k)h(n k) h(n) x(n) y(n)