Group Delay(群延迟,grd) o Given a narrowband input xnl=s(n]cos(won) for a system with frequency response H(ejiw), it Is assumed that X(e ew)is nonzero only around W=0 Group Delay I argH(en)=-do-winas then [(w)=nd it can be shown(see Problem 5.57)that the response y(n to x(n is =(2)s-noyn-9-) the time delay of the envelope sIn) is nd◆Given a narrowband input x[n]=s[n]cos(w0n) for a system with frequency response H(ejw), it is assumed that X(ejw) is nonzero only around w =w0 11 Group Delay(群延迟，grd ) ( )   0 0 0 0 [ ] cos( ) d j d w y n H e s n w = − − − n w n  n ( ) 0 arg , jw d If   H e n = − −  w   ( ) d then  w = n it can be shown (see Problem 5.57) that the response y[n] to x[n] is the time delay of the envelope s[n] is . d n Group Delay