Patent ID: 7603611
Filing Date: 2009-10-13
Classification: G11B,H03M

Abstract:
1. A maximum likelihood decoding device comprising: Viterbi detecting means for performing bit detection by performing Viterbi detection from a reproduced signal in which bit information is reproduced, said Viterbi detecting means variably setting reference levels used for branch metric calculation according to level of said reproduced signal; Euclidean distance calculating means for calculating a Euclidean distance between a maximum likelihood path as a path surviving as a result of path selection by said Viterbi detecting means and a second path compared with the maximum likelihood path; metric difference calculating means for calculating a metric difference between a value of a path metric for said second path and a value of a path metric for said maximum likelihood path on a basis of said reproduced signal, said maximum likelihood path, and said second path; sample average value calculating means for sampling a value of the Euclidean distance between said maximum likelihood path and said second path, said Euclidean distance being calculated by said Euclidean distance calculating means, and calculating an average value of said Euclidean distance; and variance value calculating means for calculating a variance value of said metric difference calculated by said metric difference calculating means.