Data defect detection using soft decision result

A data reproduction apparatus for reproducing data having maximum likelihood as recorded data in accordance with a maximum likelihood decoding algorithm corresponding to partial response using a maximum likelihood detector, the data reproduction apparatus comprising:

• a follow-up control part controlling, based on a level of a variation in the reproduced signal, necessary information for reproducing the data so that the necessary information follows the variation in the reproduced signal;
• a defect detection part for detecting a defect of the recorded data;
• and
• an initialization part fixing the necessary information to an initial value for a given period of time when said defect detection part detects the defect of the recorded data,
• wherein said defect detection part comprises:
• a waveform state detection part generating 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;
• and
• a defect determination part determining 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.

A data reproduction apparatus for reproducing data having maximum likelihood as recorded data in accordance with a maximum likelihood decoding algorithm corresponding to partial response, the data being reproduced from sampled values obtained by sampling a reproduced signal from a recording medium, the data reproduction apparatus comprising:

• a follow-up control part controlling, based on a level of a variation in the reproduced signal, necessary information for reproducing the data so that the necessary information follows the variation in the reproduced signal;
• a defect detection part for detecting a defect of the recorded data;
• and
• an initialization part fixing the necessary information to an initial value for a given period of time when said defect detection part detects the defect of the recorded data,
• wherein said defect detection part comprises:
• a waveform state detection part generating information representing a state of a waveform of the reproduced signal based on soft decision results obtained in process of reproducing the data, and
• a defect determination part determining the defect of the recorded data based on the information generated in said waveform state detection part, and
• wherein said follow-up control part increases a gain for controlling the necessary information for a subsequent given period of time after the initialization part fixes the necessary information to the initial value for the given period of time.

A defect detection device for detecting a defect of data recorded on a recording medium, the defect detection device comprising:

• a first part generating information representing a state of a waveform of a reproduced signal from the recording medium based on soft decision results obtained in process of reproducing the data in accordance with a maximum likelihood decoding algorithm corresponding to partial response;
• and
• a second part determining the defect of the recorded data based on the information generated in said first part, wherein:
• the first part generates a first signal switching between a first level corresponding to a peak value part of sampled values obtained from the reproduced signal and a second level corresponding to the other part of the sampled values than the peak value part and a second signal switching between a third level corresponding to a bottom value part of the sampled values and a fourth level corresponding to the other part of the sampled values than the bottom value part;
• and
• said second part determines the defect of the recorded data based on at least one of the first and second signal.

A data reproduction apparatus comprising:

• a defect detection part detecting a defect of data recorded on a recording medium, the defect detection part comprising:
• a first part generating information representing a state of a waveform of a reproduced signal from the recording medium directly from soft decision results obtained in process of reproducing the data in accordance with a maximum likelihood decoding algorithm corresponding to partial response, and
• a second part determining the defect of the recorded data based on the information generated in said first part;
• a control part controlling, based on a level of a variation in the reproduced signal, necessary information for reproducing the data so that the necessary information follows the variation in the reproduced signal;
• and
• an initialization part fixing the necessary information to an initial value for a given period of time when said defect detection part detects the defect of the recorded data.

A method of detecting a defect of data recorded on a recording medium, the method comprising the steps of:

• (a) obtaining soft decision results obtained in process of reproducing the data in accordance with a maximum likelihood decoding algorithm corresponding to partial response;
• (b) generating information representing a state of a waveform of a reproduced signal from the recording medium based on the soft decision results obtained in said step (a);
• and
• (c) determining the defect of the recorded data based on the information obtained in said step (b), wherein:
• said step (b) generates a first signal switching between a first level corresponding to a peak value part of sampled values obtained from the reproduced signal and a second level corresponding to the other part of the sampled values than the peak value part and a second signal switching between a third level corresponding to a bottom value part of the sampled values and a fourth level corresponding to the other part of the sampled values than the bottom value part;
• and
• said step (c) determines the defect of the recorded data based on at least one of the first and second signal.

A method of reproducing data from a recording medium, comprising:

• sampling a reproduced signal from the recording medium;
• detecting a defect of data recorded on a recording medium;
• fixing necessary information for reproducing the data to an initial value for a given period of time when said detecting detects the defect of the recorded data;
• controlling the necessary information based on a level of a variation in the reproduced signal so that the necessary information follows the variation in the reproduced signal;
• generating information representing a state of a waveform of the reproduced signal from the recording medium directly from soft decision outputs from an add-compare-select part of a maximum likelihood detector in process of reproducing the data in accordance with a maximum likelihood decoding algorithm corresponding to partial response;
• and
• determining the defect of the recorded data based on the information generated.

A method of reproducing data from a recording medium, comprising the steps of:

• (a) detecting a defect of data recorded on a recording medium;
• (b) fixing necessary information for reproducing the data to an initial value for a given period of time when said step (a) detects the defect of the recorded data;
• and
• (c) controlling the necessary information based on a level of a variation in the reproduced signal so that the necessary information follows the variation in the reproduced signal,
• wherein said step (c) increases a gain for controlling the necessary information for a subsequent given period of time after said step (b) fixes the necessary information to the initial value for the given period of time.