Digital filtering of DTV I-F signal to avoid low-end boost of the baseband signal resulting from in-phase synchrodyne
AssigneeSamsung Electronics Co., Ltd.
InventorAllen LeRoy Limberg
Life of this patent
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Abstract
In a radio receiver for digital television signals a digital filter supplies the in-phase synchrodyning circuitry a shaped spectral response to the digitized I-F signal. The amplitude-versus-frequency response of the digital filter rolls off through the carrier region, so that there is substantially no boost of the amplitudes of lower frequency components of the baseband symbol coding recovered by the in-phase synchrodyning circuitry, with respect to the amplitudes of higher frequency components of the baseband symbol coding such circuitry recovers. When the DTV receiver is initially tuned to a channel, the adaptation of the adaptive channel equalizer proceeds without having initially to compensate for the low-end boost.
Claims7
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;
- 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;
- in-phase synchrodyning circuitry for demodulating said digitized intermediate-frequency signal to recover baseband symbol coding;
- and
- adaptive baseband equalization and ghost-cancellation filtering responsive to the baseband symbol coding recovered by said in-phase synchrodyning circuitry, wherein the shaped spectral response of said digital filter is designed to improve the flatness of amplitude response and uniformity of group delay of components of said baseband symbol coding that are close to zero frequency, thereby to relieve said adaptive baseband equalization and ghost-cancellation filtering from having to provide such improvements.
Dependencies are inferred from the claim text.