Ntsc interference detectors using comb filters that suppress dtv pilot carrier to extract ntsc artifacts

Abstract From the Canadian patent

A first comb filter differentially combines an I- or Q-channel baseband signal supplied as input signal to a co-channel NTSC interference detector for a DTV receiver with that signal as subjected to a first amount of differential delay. This generates a first comb filter response in which artifacts arising from synchronous detection of the co-channel interfering analog television signal are suppressed. The detector includes a second comb filter that combines the input signal with that signal as subjected to a second amount of differential delay to generate a second comb filter response in which artifacts of the co-channel interference are reinforced. The first and second comb filters both …