Signal quality evaluation apparatus, signal quality evaluation value generation method, reproduction apparatus

摘要

It is possible to obtain a signal quality evaluation value that can have high error rate correlation, that is, high accuracy, for a high density recording reproduction signal. Therefore, the estimated value of the path selection error rate is calculated based on the distribution of the path metric difference of the maximum likelihood path of each time which is the detection path in maximum likelihood decoding in the PRML decoding system and the second path having the second highest likelihood. Ask. Further, the average number of error bits in the erroneous detection is obtained from the number of bit differences between the maximum likelihood path and the second path at the time of path selection at each time in maximum likelihood decoding. Then, an estimated bit error rate is obtained from these results, and an evaluation value corresponding to the estimated bit error rate is generated.