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PASM and TASM forward error correction and detection code method and apparatus

  • US 4,849,976 A
  • Filed: 08/03/1987
  • Issued: 07/18/1989
  • Est. Priority Date: 08/03/1987
  • Status: Expired due to Term
First Claim
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1. A process for encoding a PASM error correcting and detecting code comprising the steps of:

  • storing a block of a data-symbol sequence having data symbols with p-bits per symbol, in memory means having information-memory cells and parity-check memory cells;

    calculating a first set of parity-check symbols from the data symbols along a first set of parity lines, by setting the parity-check symbol for each of the first set of parity-check symbols for each parity line equal to the modulo-2p sum of the data symbols along each parity line, wherein each parity line of the first set of parity lines has a path with a first slope traversing through said information-memory cells, and said first set of parity-check symbols forms a first parity row located in said parity-check memory cells;

    calculating at least a second set of parity-check symbols from the data symbols and parity-check symbols along a second set of parity lines, by setting the parity-check symbol for each of the second set of parity-check symbols for each parity line equal to the modulo-2p sum of the data symbols and parity-check symbols along each parity line, wherein each parity line of the second set of parity lines has a path with a second slope traversing through said information-memory cells and through said first parity row, and said second set of parity-check symbols form a second parity row located in said parity-check memory cells; and

    outputting an encoded-data-symbol sequence comprising the data-symbol sequence and the parity-check symbols.

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