REPRODUCED SIGNAL EVALUATING METHOD, INFORMATION RECORDING MEDIUM, REPRODUCING DEVICE, AND RECORDING DEVICE

摘要

A reproduced signal evaluating method includes a step of generating a binary signal by the PRML signal processing from the signal generated by reproducing a data sequence which is a combination of marks and spaces and is recorded on an information recording medium on which the data sequence can be recorded and a difference calculating step of calculating a difference metric by using the most probable first and second state transition sequences obtained from the binary signal and using the reproduced signal.  The variation of the position of the edge of the shortest mark in a pattern where the shortest space is adjacent to and in front of or behind the shortest mark is determined from the calculated difference metric of either a first pattern where the length of the space adjacent to the shortest mark and not adjacent to the shortest space is larger than the shortest space or a second pattern where the length of the mark adjacent to the shortest space and not adjacent to the shortest mark is longer than the shortest mark.