| 摘要 |
PURPOSE:To improve the error detection capability and error correction capability by executing one error correction in addition to erasure correction the same number as error location number when a difference between an inter-code minimum distance and an erroneous location is 3 or over. CONSTITUTION:An external code decoder 12 judges whether number or symbols having an error is 2 or below or 3 or over, and when the symbol number having an error is 2 or below, error correction is executed when the number is 3 symbols or over, one error correction is executed for the erasure correction. That is, an error flag is inputted to a storage circuit 15 by an error flag input circuit 16. Syndromes S0-S7 are calculated based on the error flag by a syndrome calculating circuit 17. Moreover, the multiplication or addition on the Galois field GF is executed by an arithmetic circuit 18 and a root circuit 19 obtains the solution of a quadratic equation according to the algorithm of a chain. Then a correction execution circuit 20 applies error correction to a code data with an error to be detected.
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