relative specifications: maximum magnitude in passband is normalized to l, viz. odB 20*log10(1 0 maximum attenuation in passband 20*log106>0 minimum attenuation in stopband BdB cutoff frequency: H(e/)=l/√2 20log1o H(ec)=3dB magnitude response of equivalent analog system H(eJo)l Heff(jQ2) T } T digital specification, finally: @p=Qp 1, as=Q25T'relative specifications：maximum magnitude in passband is normalized to 1, viz. 0dB 20*log 0 20*log 1 0 10 10 = −  = − −  s s p p    （  ） maximum attenuation in passband minimum attenuation in stopband 3dB cutoff frequency： H e dB H e c c j j 20log | ( ) | 3 | ( ) | 1/ 2 − 10 = =    p = p T,s = s T            = = T T H e H j T j eff     0 | | ( ) | | | ( ) magnitude response of equivalent analog system: digital specification, finally: