Patent ID: 7342981
Filing Date: 2008-03-11
Classification: H04L

Abstract:
1. A digital receiver for demodulating a digital signal modulated onto a carrier, comprising: a tuner; an analog to digital converter, for digitizing a channel tuned by said tuner to provide a digitized channel; a coarse carrier recovery circuit for extracting said digital signal from said digitized channel at near baseband; a feed forward equalizer receiving said digital signal at near baseband and outputting a feed forward equalized signal; a fine carrier recovery circuit for phase shifting said feed forward equalized signal by a phase correction angle to adjust for remaining offsets in phase and frequency of said feed forward equalized signal attributable to phase and frequency offsets in said carrier; said fine carrier recovery circuit comprising a phase error detector for estimating errors in real and imaginary components of said digital signal, a filter for filtering the estimate of phase error in said carrier to control said phase correction angle, wherein at least one filter parameter of said filter varies adaptively with said phase error, and wherein said phase error detector has at least two modes of operation for uniquely estimating errors in said imaginary component in each of said at least two modes, and wherein a first of said two modes is for high guality signals.