Patent ID: 6628730
Filing Date: 2003-09-30
Classification: H04L,H04N

Abstract:
An apparatus for demodulating a digital video broadcast signal comprising data modulated on a plurality of spaced carrier frequencies, comprising:a transform circuit configured to analyze digital sample values derived from said broadcast signals; and a timing synchronization circuit configured to synchronize the transform circuit with symbol periods of the broadcast signal, process a complex product signal to derive timing synchronization pulses, and to operate in (i) a first mode for analyzing the digital sample values over a relatively wide timing range to establish synchronization and (ii) a second mode for analyzing the digital sample values over a relatively narrow range about a synchronization point, wherein said timing synchronization circuit comprises (i) a correlation circuit configured to receive the digital signal values, (ii) a delay circuit having a delay time period equal to a symbol period and (iii) a multiplier circuit configured to (a) receive the digital signal values and a version thereof delayed by said delay circuit and (b) form said complex product signal.