Signal quality evaluation device, information read/write device, signal quality evaluation method, write conditions determining method, signal quality evaluation computer program, computer-readable storage medium containing signal quality evaluation computer program

摘要

A Viterbi decoding circuit performs Viterbi decoding on the basis of a reproduced signal obtained by reading an optical disc. A decoded bit sequence is fed to a first specific pattern detection circuit and a first reverse pattern detection circuit. A path metric difference ΔM is fed to a reproduced signal evaluation circuit. The reproduced signal evaluation circuit extracts path metric differences for a specific pattern and a reverse pattern detected by the first specific pattern detection circuit and the first reverse pattern detection circuit and evaluates the reproduced signal on the basis of results. The evaluation uses not only the bit sequence for which the ideal SAM value is a minimum. The invention achieves accurate evaluation for reproduction.