Demodulating digital video broadcast signals

摘要

A demodulator suitable for implementation in a single chip for demodulating digital video broadcast signals including data modulated on a multiplicity of spaced carrier frequencies, wherein an input broadcast signal is converted to a frequency sufficiently low to enable analog digital conversion of the signal. The demodulator includes an analog to digital converter for converting the broadcast signal to a series of digital samples; a real to complex converter for converting each digital sample to a complex number value; Fourier transformer for analyzing the complex number values to provide a series of data symbol values for each carrier frequency; a signal processor for receiving the data symbol values and providing an output for decoding; and a timing synchronizer for synchronizing the Fourier transformer with the symbol periods of the broadcast signal. The synchronizer includes a correlation for receiving the data sample values and including a delay having a time period delay equal to the active symbol period, and a multiplier for receiving the data symbol values and a version thereof delayed by the delay, to form a complex product signal, and a filter for filtering the complex product signal. The timing synchronizer includes a coarse synchronizer employing a subset of the data sample values for providing a course timing synchronization, and a fine synchronizer for providing a fine synchronization within a time period determined by the coarse synchronization.