Patent ID: 7573794

Claim:
A defect detection device for detecting a defect of recorded data in a data reproduction apparatus for reproducing data having maximum likelihood as the recorded data in accordance with a maximum likelihood decoding algorithm corresponding to partial response using a maximum likelihood detector connected to the defect detection device, the defect detection device comprising: a waveform state detection part configured to generate information representing a state of a waveform of the reproduced signal based on soft decision results obtained from an add-compare-select part of the maximum likelihood detector in process of reproducing the data, the soft decision results obtained from the add-compare-select part being also input to a path memory of the maximum likelihood detector, the soft decision results being based on path metric values stored in a path metric memory connected to the add-compare-select part; and a defect determination part configured to determine the defect of the recorded data based on the information generated in said waveform state detection part, wherein the waveform state detection part is directly connected to the add-compare-select part and the data being reproduced is from sampled values obtained by sampling a reproduced signal from a recording medium.