Group delay( 群延迟，gd) Another particularly useful representation of phase is through the group delay: all value ()-grdu is correct! continuous group delay can be obtained from the principal value,except at the discontinuities,or,from ambiguous phase:grd[H(e】=a{∠Hleo} ignoring impulses caused by discontinuities. ambiguous phase∠H(em）=ARGH(em】+2rr(o) ,arbitrary(o） 13Group Delay(群延迟，grd ) ( )  ( ) arg ( ) j j d grd H e H e d      = =− group delay can be obtained from the principal value, except at the discontinuities, ◆Another particularly useful representation of phase is through the group delay: ( )  ( ) 2 ( ) H e H j j ARG r e  = +     continuous ambiguous phase , arbitrary r() 13  ( )  ( ). j j d g d H e H e d r    =−  ignoring impulses caused by discontinuities. or, from ambiguous phase: all value is correct!