Patent ID: 7664208
Filing Date: 2010-02-16
Classification: G11B,H03M,H04L

Abstract:
1. An evaluating device comprising: Viterbi detecting means for performing bit detection by performing Viterbi detection from a reproduced signal in which bit information is reproduced; metric difference calculating means for calculating a metric difference as a difference between a value of a path metric for a second path and a value of a path metric for a maximum likelihood path when at least an error pattern between said maximum likelihood path as a path surviving as a result of path selection by said Viterbi detecting means and said second path compared finally with said maximum likelihood path corresponds to one of a predetermined plurality of error patterns; evaluation value calculating means for comparing each of values of metric differences for each said error pattern, said metric differences being calculated by said metric difference calculating means, with an individual threshold value obtained by dividing a Euclidean distance between said maximum likelihood path and said second path in each said error pattern by a common value, and calculating a total number of values of said metric differences less than said threshold value as an evaluation value; and first error pattern determining means for determining whether or not the error pattern between said maximum likelihood path and said second path corresponds to one of said predetermined plurality of error patterns on the basis of information of a bit sequence of said maximum likelihood path and information of a bit sequence of said second path obtained by said Viterbi detecting means, wherein said metric difference calculating means calculates a value of said metric difference for said maximum likelihood path and said second path corresponding to one of said predetermined plurality of error patterns on the basis of a result of determination of said first error pattern determining means, and said evaluation value calculating means calculates the Euclidean distance between said maximum likelihood path and said second path in each said error pattern on the basis of the result of determination of said first error pattern determining means.