Q. A discrete-time all-pass system has two of its poles at 0.25∠0° and 2 ∠30° Which one of the following statements about the system is TRUE?
A. It has two more poles at 0.5Ð30and 4Ð0 .
B. It is stable only when the impulse response is two-sided.
C. It has constant phase response over all frequencies.
D. It has constant phase response over the entire z-plane.
Ans: It is stable only when the impulse response is two-sided.