6 Time and frequency characterization of s&S 6.2.2 Group delay Definition ( o ∠H(jO) d EXample: y(t)=x(t-to) Ho=e ∠H()=-ot0 r(o=to (signal delay) Distortionless system T(o)is flat6 Time and frequency characterization of S&S 6.2.2 Group Delay ( ) ( ) ( ) ( ) ( ) ( ) 0 0 0 0 t signal delay H j t H j e y t x t t j t =  = − = = − −       Definition: ( ) ( )    H j d d = −  Example: Distortionless system: is flat.  ()