9.3 • DIGITAL SIGNAL F ILTERS 393- (a) Constr uct a filter using the zeros e ±~•· and e-^1 • = -1 for "zeroing
out" cos(2; n), sin(2; n), and cos(7rn).
(b) Construct a filter using the poles ge~ and ~e^0 • = ~ for "boosting
up" signals near cos(~n) and sin ( ~n).
(c) Construct t he combination filter using the zeros and poles in parts (a)
and (b).