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Error correction systems with modified Viterbi decoding

  • US 5,539,757 A
  • Filed: 12/22/1993
  • Issued: 07/23/1996
  • Est. Priority Date: 12/22/1993
  • Status: Expired due to Fees
First Claim
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1. A communication system, comprising:

  • a channel;

    a modulator at one end of the channel and a demodulator at the other end of the channel;

    a convolutional encoder having a constant length K and N=2.sup.(K-1) states and responsive to a data source and coupled to the modulator;

    a modified Viterbi decoder coupled to said demodulator;

    said decoder including means for reading successive words from the demodulator;

    said decoder including means for calculating kernel metric increments for only N/2 states;

    said decoder including selector means for comparing accumulative metrics for each metric increment and selecting survivors for two new states; and

    tracing means in said decoder for tracing back from a zero state;

    said calculating means being for calculating up to N/2 metrics.

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