Patent ID: 6023306
Filing Date: 2000-02-08
Classification: H04L,H04N

Abstract:
An NTSC interference detector incorporated within a digital high-definition television receiver including a demodulator for extracting a received I-channel baseband signal susceptible of being accompanied at times by respective co-channel interfering NTSC signal components, said NTSC interference detector comprising:an NTSC extracting filter for supplying an NTSC extracting filter response that separates accompanying co-channel interfering NTSC signal component from said received I-channel baseband signal and an accompanying direct bias signal, said NTSC extracting filter comprisinga first comb filter, said first comb filter includinga first delay circuit for supplying in response to said received I-channel baseband signal differentially delayed signals with a prescribed amount of differential delay equal to the duration of an even number of horizontal scanning periods of NTSC signal as will generate said co-channel interfering NTSC signal components, said comb filter further includinga first subtractor for differentially combining said differentially delayed signals to generate the response of said first comb filter;a comparing portion for periodically integrating said NTSC extracting filter response and deciding whether said co-channel interfering NTSC signal component separated from said received I-channel baseband signal is above a first reference value or not; anda control signal generator for accumulating the signal supplied from said comparing portion for each integration period, deciding the presence or absence of said co-channel interfering NTSC signal components according to a second reference value, and supplying a control signal according to the presence or absence of said co-channel interfering NTSC signal component in said received I-channel baseband signal.