Signal quality evaluation device, signal quality evaluation value generation method, and reproduction device

A reproduction device comprising:

• a reproduction unit configured to reproduce a reproduction signal of bit information from a recording medium;
• a decoding unit configured to perform PRML decoding processing by partial response equalization and maximum likelihood decoding for the reproduction signal to decode binarized data;
• a first arithmetic unit configured to obtain an estimated value of a path selection error rate on a basis of a distribution of a path metric difference between a maximum likelihood path of each time, the maximum likelihood path being a detection path in the maximum likelihood decoding, and a second path having a second highest likelihood;
• a second arithmetic unit configured to obtain an average error bit number in erroneous detection from a bit difference number between the maximum likelihood path and the second path at a time of path selection of each time in the maximum likelihood decoding;
• and
• an evaluation value generation unit configured to obtain an estimated bit error rate from arithmetic results by the first arithmetic unit and the second arithmetic unit, and generate an evaluation value according to the estimated bit error rate.

A signal quality evaluation value generation method comprising:

• a first arithmetic process of obtaining an estimated value of a path selection error rate on a basis of a distribution of a path metric difference between a maximum likelihood path of each time, the maximum likelihood path being a detection path in maximum likelihood decoding, and a second path having a second highest likelihood in a PRML decoding system to perform partial response equalization and the maximum likelihood decoding for a reproduction signal of bit information;
• a second arithmetic process of obtaining an average error bit number in erroneous detection from a bit difference number between the maximum likelihood path and the second path at a time of path selection of each time in the maximum likelihood decoding;
• and
• an evaluation value generation process of obtaining an estimated bit error rate from arithmetic results by the first arithmetic process and the second arithmetic process, and generating an evaluation value according to the estimated bit error rate.