7.1 Filter Specifications nd constraints on phase response other than implicit requirements of stability and causality for IIR filter. The constraint for FIR filters:linear phase. H(ej)l 容差极限 In passband, tolerance scheme容限图 1+δp H()may vary symmetrically around 1,1=p2 1 1- 1-82H(el@)31+p,laop P2 or1-o2H(eoKl,osδ1=0 Passband Transition Stopband In stopband,lH(eo)l≤δs,ozos cutoff frequency edge frequency 0 W T 1通带边界（截止）频率 阻带边界（截止）频率11 7.1 Filter Specifications tolerance scheme 容限图 edge frequency |H(e j)| may vary symmetrically around 1, δp1=δp2 or ,δp1=0 cutoff frequency 1 c 容差极限 通带边界(截止)频率 阻带边界(截止)频率 P S 1- 1 p2 ( ) H j e    ，  p 1- 1+ p p 2 1 ( ) H j e      ，  p In passband, In stopband, |H(e j)|≤δs , ||≥s ◆no constraints on phase response other than implicit requirements of stability and causality for IIR filter. ◆The constraint for FIR filters: linear phase