Frequency-Selective Filters Ideal bandstop filter(discrete-time system H,(en) <1 others H -10 Frequency-Selective Filters ◆Ideal bandstop filter(discrete-time system) ( )     = others w w w H e j w c c bs 1, 0, 1 2 0 1 wc 1 − − wc  ( ) jw H e 1 2 wc 2 − wc