Patent ID: 6823489
Filing Date: 2004-11-23
Classification: H04L

Abstract:
An apparatus for reconstructing symbol values from trace back path information stored within a trellis decoder, said apparatus being part of a receiver configured for decoding trellis encoded signals, the receiver comprising: said trellis decoder and a decision feedback equalizer coupled to each path memory output of said trellis decoder, wherein said decision feedback equalizer is of configured for obtaining symbol values from each path memory output of said trellis decoder for use as estimates in channel equalization, said apparatus comprising data signal selection circuitry for obtaining values for four bits, S.sub.3, S.sub.2, S.sub.1, S.sub.0, that represent a reconstructed symbol, a value for S.sub.3 representing the most significant bit of said reconstructcd symbol, wherein said data signal selection circuitry comprises: a multiplexer having four inputs where each of said four inputs provides a subset bit delay input value, said multiplexer configured for selecting one of said four input values as signal Z.sub.2 in response to selection input signals from trace back unit inputs D.sub.1 and D.sub.0; and an inverter coupled to an output of said multiplexer, said inverter configured for providing an inverse of signal Z.sub.2 as signal S.sub.3.