A co-channel filter for CATV

A rigorous approach permits a co-channel filter design which effectively removes the beat interference of a weaker, but still noticeable, TV station on the same channel as a desired station. Unlike previous designs, the present filter does not rely on the strength or direction of the interfering station. Rather, it uses a novel multi-frequency, multipath, phase reversal technique to accomplish cancellation of the bandpass containing the beat interference without accompanying phase distortion, as occurs in conventional filters. The co-channel filter, designed to be used after demodulation to base-band, is equipped with a meter at the beat frequency for proper adjustment of the frequency and notch depth controls.