Patent ID: 6760078
Filing Date: 2004-07-06
Classification: H03J,H04N

Abstract:
A radio signal receiver for vestigial sideband digital television signals, said receiver comprising:a tuner for converting the vestigial-sideband amplitude modulation of a selected digital radio signal to an analog intermediate-frequency signal that exhibits a channel response without a prescribed raised cosine roll-off through carrier frequency; analog-to-digital conversion circuitry for converting said analog intermediate-frequency signal to a digitized intermediate-frequency signal; a digital filter for generating a shaped spectral response to said digitized intermediate-frequency signal, which said shaped spectral response adjusts overall channel response to provide a linear-phase approximation to said prescribed raised cosine roll-off through carrier frequency; in-phase synchrodyning circuitry for demodulating said shaped spectral response to said digitized intermediate-frequency signal to recover baseband symbol coding with a tendency of the amplitudes of lower frequency components of the baseband symbol coding recovered by the in-phase synchrodyning circuitry being boosted with respect to the amplitudes of mid-band frequency components of the baseband symbol coding, which tendency is suppressed by said digital filter adjusting said overall channel response to provide a linear-phase approximation to said prescribed raised cosine roll-off through carrier frequency; and adaptive baseband equalization and ghost-cancellation filtering responsive to the baseband symbol coding recovered by said in-phase synchrodyning circuitry, equalization against said boost of the amplitudes of lower frequency components of the baseband symbol coding recovered by the in-phase synchrodyning circuitry not being required of said adaptive baseband equalization and ghost-cancellation filtering, at least in part because said digital filter suppresses said tendency of the amplitudes of lower frequency components of the baseband symbol coding recovered by the in-phase synchrodyning circuitry being boosted with respect to the amplitudes of mid-band frequency components of the baseband symbol coding.