Definitions for "Notch filter"
A filter which blocks a narrow band of frequencies and passes all frequencies above and below the band.
A notch filter helps to remove a small section of the video signal that contains excess color information. This helps to eliminate some unwanted color effects. The circuit however contributes to a small degradation in picture resolution.
A special type of cut-only equalizer used to attenuate ( only, no boosting provisions exist) a narrow band of frequencies. Three controls: frequency, bandwidth and depth, determine the notch. Simplified units provide only one or two controls, with bandwidth and/or depth fixed internally. Used most often in acoustic feedback control to eliminate a small band of frequencies where the system wants to howl (feedback). See narrow-band filter.
Keywords:  fixed, high
an EQ with a very high fixed Q