Patent ID: 6320917
Filing Date: 2001-11-20
Classification: H04L,H04N

Abstract:
An apparatus for demodulating digital video broadcast signals comprising data modulated on a multiplicity of spaced carrier frequencies, comprising:analog-to-digital conversion means for providing a series of digital samples of the broadcast signal;transform means for analyzing the samples to provide a series of data symbol values for each carrier frequency;signal processing means for processing the series of data symbol values including phase error correcting means; andautomatic frequency control means for controlling the frequency of the signals input to the transform means;wherein the automatic frequency control means includes coarse frequency control means for controlling the frequency in terms of increments of the carrier spacing frequency, and fine frequency control means for controlling the frequency for values less than a single carrier spacing frequency interval; andwherein the coarse frequency means includes a filter means for assessing a group of a predetermined number (N) of carrier signals on either side of the nominal position of a plurality of predetermined continual pilot signals, wherein the outputs of the filter means are provided to respective memory locations of memory means, the memory means being divided into a plurality of sections, first means for determining within each section a first signal best representing the continual pilot signal, and second means for determining from among the first signals from the plurality of sections, a second signal which best represents the continual pilot signal.