Generation of decision feedback equalizer data using trellis decoder traceback output in an ATSC HDTV receiver

摘要

For use in a receiver capable of decoding trellis encoded signals of the type comprising a trellis decoder and a decision feedback equalizer coupled to each path memory output of said trellis decoder, wherein said decision feedback equalizer is capable of obtaining symbol values from each path memory output of said trellis decoder for use as estimates in channel equalization, an apparatus and method is disclosed for reconstructing symbol values from trace back path information stored within said trellis decoder. The apparatus and method of the present invention reconstructs a symbol stream from the trellis decoder using data signal selection circuitry to obtain bit values that represent the reconstructed symbols. In one embodiment of the present invention, each of a plurality of multiplexers selects one of four symbol value inputs to send to a first adaptive filter tap cell in a set of twelve adaptive filter tap cells. The four symbol values represent (1) a symbol at trellis point “t”, and (2) a symbol at trellis point “t−12”, and (3) a symbol having the value “plus five”, and (4) a symbol having the value “minus five.”