Patent ID: 7213195

Claim:
A data decoding method for converting an input signal sequence to a decoded code data sequence by using maximum likelihood data sequence decoding method, a first step of referring to an input signal sequence input for data detection by using said maximum likelihood data sequence detection method and a first decoded code data sequence decoded for said input signal sequence by using said maximum likelihood data sequence detection method, and calculating likelihood values (probabilities) that error events having preset predetermined code error patterns occur at each code position on said first decoded code data sequence; a second step of referring to contents of decoded code values at the position of a relevant decoded code, for which each likelihood value is calculated at said first step, and positions of before and after the relevant decoded code over a predetermined code length, and setting a predetermined reference value associated with the referred-to contents of the decoded code values; a third step of comparing each likelihood value calculated at said first step with the reference value set at the second step; and a fourth step of inverting code values included in code values of said first decoded code data sequence and of which the decoded code position is associated with said predetermined code error pattern, based on a result of said third step, thereby generating a second decoded code data sequence, and outputting the second decoded code data sequence as a resulting decoded code data sequence.