Patent ID: 6137847
Filing Date: 2000-10-24
Classification: H04L,H04N

Abstract:
An apparatus for demodulating digital video broadcast signals comprising data modulated on a multiplicity of spaced carrier frequencies, comprising:conversion means for converting a down-converted version of the broadcast signal to a series of digital samples in complex format;transform means for analyzing the digital sample values to provide a series of data symbol values for each carrier frequency;signal processing means for receiving the data symbol values and providing an output for decoding; andtiming synchronization means for synchronizing the transform means with symbol periods of the broadcast signal, including correlation means for receiving the digital sample values and comprising delay means having a time period delay equal to the active symbol period, and multiplier means for receiving the digital sample values and a version thereof delayed by said delay means, to form a complex product signal, and means for processing the complex product signal to derive timing synchronization pulses, wherein the timing synchronization means comprises a coarse synchronization means employing a subset of the digital sample values for providing a coarse timing synchronization, and a fine synchronization means for providing a fine timing synchronization within a time period determined by the coarse synchronization means.