| 摘要 |
PURPOSE: A method for viterbi-decoding data in optical disk reproducing system is provided to decrease the bit error rate of a decoded data by decoding a signal with RLL(Run Length Limited) characteristic of an EFM(Eight-to-Fourteen Modulation) code or an EEMplus code. CONSTITUTION: Variables(CF1,CF2,CF3) for counting a number of successively determination of shift path types(I,II,III) and a variable(P) for counting a number of determination of a shift path type(II) are initialized(S101). A yk is received(S102) and an estimation amount to the yk is calculated(S103). It is judged as whether the CF1 value is greater than 0 and less than 3(S104). It is judged as whether the CF3 value is greater than 0 and less than 3 when the CF1 value is greater than 3(S105). It is judged as whether an estimation amount(M) is greater than 3 when the CF3 value is greater than 3(S106). It is judged as whether the estimation amount(M) is less than 1 when the M value is less than 3(S107). A shift path type to the yk is determined as the shift path type(II) when the estimation amount(M) is greater than 1 and a variable(FORM) for indicating a shift path type is set as 2, and then 1 is added to variables(CF2,P).
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