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