A recursive NTSC canceler to reduce co-channel interference into HDTV broadcasts

A modulation-independent method of reducing NTSC (National Television System Committee) co-channel interference into ATV (advanced television) signals is described. The design utilizes tunable, parallel connected, narrow-bandwidth IIR (infinite impulse response) filters to isolate and cancel the major components of NTSC. The canceler has been fully simulated and tested against actual NTSC signals corrupting a 32 QAM (quadrature amplitude modulation) signal. The canceler, based on notch filtering the audio, chrominance, and luminance carrier components, can increase the probability of detection by a least 3 dB compared to the same demodulator without a canceler. The detection probability increases by 1 dB per each additional luminance sideband notch filter pair.<
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