Introduce According to the length of their impulse response sequences, the digital filters are usually classified as Infinite impulse response(iir)filters ∑b- H(=) 1+>an o Finite impulse response(FIr)filters N-1 H(2)=∑(m)n 2021年12月5日2时7分2021年12月5日2时7分 Introduce According to the length of their impulse response sequences, the digital filters are usually classified as: ◆Infinite impulse response (IIR) filters ◆Finite impulse response (FIR) filters 0 1 ( ) 1 M r r r N k k k b z H z a z − = − = = +   1 0 ( ) ( ) N n n H z h n z − − = = 