Patent ID: 6667760
Filing Date: 2003-12-23
Classification: H03D,H04L,H04N

Abstract:
A radio receiver for a vestigial sideband digital television signal in which a frequency spectrum of a vestigial sideband is rolled off at some point removed from a suppressed carrier, and a pilot carrier is transmitted at a frequency of the suppressed carrier, said vestigial sideband digital television signal at times being undesirably accompanied by a co-channel analog television signal, said radio receiver comprising:tuner circuitry for supplying an intermediate-frequency signal in response to said vestigial side and digital television signal; co-channel interference filter circuitry selectively responsive to frequencies in said intemediate-frequency signal containing most of energy of said vestigial sideband digital television signal for suppressing intervening frequencies in said intermediate-frequency signal containing little of the energy of said vestigial sideband digital television signal, but apt to contain a substantial portion of energy of said co-channel analog television signal; a complex demodulator for supplying in-phase and quadrature-phase synchronous detection responses to said intermediate-frequency signal; Hilbert transformation circuitry for supplying a Hilbert transform response to said quadrature-phase synchronous detection response; filter circuitry for separating a low-frequency portion of said Hilbert transform response; and a combiner for combining said low-frequency portion of said Hilbert transform response with said in-phase synchronous detection response, and for suppressing demodulation artifacts of said co-channel analog television signal that otherwise accompany said in-phase synchronous detection response in a combiner output signal.