5.1.1 Frequency Response Phase and Group Delay To understand the effect of the phase and the group delay of a linear system,first consider the ideal delay system: yn =xn-na. ◆The impulse response haln]=n-na The frequency response Hid(ej)-e jon H(el,∠Hna(eo）=-u,ll水k元 145.1.1 Frequency Response Phase and Group Delay     hid n =  n − nd     n nd y n = x − ( ) d j j n H e e id   − = ( ) 1, j H e id  = ( ) , j H e n id d  =−      ◆The frequency response ◆The impulse response ◆To understand the effect of the phase and the group delay of a linear system, first consider the ideal delay system: 14