MULTI-MODE EQUALIZER IN A DIGITAL VIDEO SIGNAL PROCESSING SYSTEM

摘要

A DIGITAL HIGH DEFINITION TELEVISION RECEIVER EQUALIZER SYSTEM INCLUDES AN INPUT ADAPTIVE FEED FORWARD FILTER (FFF 20), A CARRIER RECOVERY NETWORK (46), AND A SLICER (40) IN ADDITION TO AN ADAPTIVE DECISION FEEDBACK FILTER (DFF, 30) FOR REMOVING INTERSYMBOL INTERFERENCE. AT THE BEGINNING OF A BLIND EQUALIZING INTERVAL THE FFF IS NOT ADAPTED AND THE DFF OPERATES AS A LINEAR FILTER WITH ADAPTED COEFFICIENTS FOR EQUALIZING POST-GHOSTS. AFTERWARDS IN THE BLIND INTERVAL THE FFF COEFFICIENTS ARE ADAPTED BLINDLY FOR EQUALIZING PREGHOSTS. IN A SUBSEQUENT DECISION-DIRECTED MODE THE SLICER OUTPUT IS USED FOR ADAPTING BOTH THE FFF AND DFF NON-LINEARLY. (FIG.4)