effect of phase and group delay of a linear system Given a narrowband input x[n]=s[n]cos(@n) for a system with frequency response H(ej), assume X(ej)is nonzero only around @=@ Around =@approximately, Group Delay arg[IH(eo]≈-4-ou, then t(@)-na it can be shown(see Problem5.63(二版5.57) that the responsey]to xIn]is MnHH(ei)s[n-nalcos(a(n-na) 0 the time delay of the envelope sIn]is n. -0 20◆Given a narrowband input x[n]=s[n]cos(0n) for a system with frequency response H(e j ) , arg ,  ( ) 0 j H e nd  − −   ( ) nd then   = it can be shown (see Problem 5.63(二版5.57)) that the response y[n] to x[n] is the time delay of the envelope s[n] is . nd Group Delay assume X(e j ) is nonzero only around  =0 , effect of phase and group delay of a linear system 20 ( )   ( ) 0 0 0 [ ] cos( ) d j y n H e s n n n nd =  − −  − Around  =0 , approximately