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Source dependent channel coding with error protection

  • US 5,091,945 A
  • Filed: 09/28/1989
  • Issued: 02/25/1992
  • Est. Priority Date: 09/28/1989
  • Status: Expired due to Term
First Claim
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1. Speech processing apparatus comprisingspeech analyzer means responsive to input speech signals from a source of input speech signals for generating a plurality of parameter signals representing said input speech signals in accordance with a speech model, at least one of said parameter signals being quantized as one of p levels,channel encoder means comprisingencoder memory means for storing an encoding table defining a mapping from each of said p levels to a unique one of p, m-bit label signals, where p<

  • k=2m, andmeans responsive to said speech analyzer means for transmitting, over a channel to a destination, the one of said p label signals that is associated with said one of said p levels in said encoding table,channel decoder means comprisingdecoder memory means for storing a decoding table defining the inverse of said encoding table mapping andmeans, responsive to a label signal received at said destination from said channel, for decoding said received label signal as the one of said p levels associated with said received label signal in said decoding table inverse mapping when said received label signal is one of said p label signals, and for decoding said received label signal in accordance with an error routine when said received label signal is one of the k-p, m-bit label signals other than said p label signals, andspeech synthesizer means responsive to said decoding means for synthesizing speech based at least in part on said decoded label signal,wherein said encoding table mapping stored by said encoder memory means and said decoding table inverse mapping stored by said decoder memory means are obtained to minimize the effect of channel errors and are obtained using simulated annealing based on a probability distribution of said p levels for said one parameter signal.

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