SYMBOL DECODING APPARATUS WITH PLURAL DATA SLICERS AND AN ADAPTIVE NTSC CO-CHANNEL INTERFERENCE FILTER

摘要

A first data slicer provides interim symbol decoding results responsive to multiple-level symbols in a digital television (DTV) receiver. Co-channel in terference accompanying the multiple-level symbols is suppressed by using a first comb filter to reduce the energy of the co-channel interference before data slicing in a se cond data slicer. The first comb filter incidentally recodes the symbols supplied to t he second data slicer. A second comb filter is used as a postcoder after the second da ta slicer, re-coding the data stream recovered by the second data slicer to generate su pplemental symbol decoding results. Co-channel interference detector circuitry determin es the amounts of co-channel interference energy in the interim and supplemental sy mboldecoding results. The interim symbol decoding result s are available for use as final symbol decoding results only in the co-channel interference detector does no t generate a current indication that the stream of symbols reproduced in the DTV receiv er is accompanied by artifacts of co-channel interfering analog television signal that can be suppressed in the first comb filter response and that are of sufficient ener gy level to cause uncorrectable error in the data from the first data slicer.