§4.2 The Frequency Response The function H(ejo) is called the magnitude response and the function 0(a)is called the phase response of the lti discrete-time system Design specifications for the lti discrete-time system, in many applications, are given in terms of the magnitude response or the phase response or both§4.2 The Frequency Response • The function | H(ej) | is called the magnitude response and the function () is called the phase response of the LTI discrete-time system • Design specifications for the LTI discrete-time system, in many applications, are given in terms of the magnitude response or the phase response or both