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 interf erence accompanying the multiple-level symbols is suppressed by using a first comb filt er to reduce the energy of the co-channel interference before data slicing in a second data slicer. The first comb filter incidentally recodes the symbols supplied to the s econd data slicer. A second comb filter is used as a postcoder after the second data s licer, re-coding the data stream recovered by the second data slicer to generate supple mental symbol decoding results. Co-channel interference detector circuitry determines t he amounts of co-channel interference energy in the interim and supplemental symbol decoding results. The interim symbol decoding results are available for use as f inal symbol decoding results only in the co-channel interference detector does not ge nerate a current indication that the stream of symbols reproduced in the DTV receiver i s 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 energy l evel to cause uncorrectable error in the data from the first data slicer.