Method and apparatus for amplitude limiting a composite signal

摘要

Two parallel signal paths carry a composite signal having a narrow-band component such as an FM station's composite signal. The first path includes a notch filter that removes the narrow-band component, such as the FM stereo pilot tone, from the composite signal and also includes a reciprocal clipper coupled to the output of the notch filter that selects peaks beyond given maximum and minimum limits from the remainder of the composite signal. These peaks are then effectively subtracted from the corresponding peaks of the composite signal in the second path and the resultant signal is used to modulate the station's carrier frequency. The resultant signal is an amplitude limited composite signal in which the narrow-band component is substantially unimpaired even though the composite signal has been amplitude limited.