Data reproduction control method and apparatus, and optical disk unit

A data reproduction control apparatus controlling a distribution characteristic of quantized data by adjusting a waveform equalization characteristic of a waveform equalizer when a signal reproduced from a recording medium recorded with data in accordance with a given recording code is subjected to operations in quantization means and the waveform equalizer, the data reproduction control apparatus comprising:

• counting means for counting frequencies of levels of the quantized data;
• and
• equalization characteristic adjustment means for adjusting the waveform equalization characteristic of the waveform equalizer so that a distribution of the frequencies of the levels obtained in said counting means approaches a distribution that should be obtained based on the given recording code.

A data reproduction control method performing quantization on a signal reproduced from a recording medium recorded with data in accordance with a given recording code, and controlling a data reproduction characteristic at a time of determining, by a maximum likelihood detection process corresponding to the recording code, reproduced data from quantized data obtained by the quantization, wherein:

• frequencies of levels of the quantized data are counted;
• and
• a processing characteristic in the maximum likelihood detection process is adjusted based on a distribution of the counted frequencies of the levels.

A data reproduction control method performing, at given intervals, sampling of a signal reproduced from a recording medium recorded with data in accordance with a code of partial response, and determining, in accordance with a Viterbi decoding algorithm, reproduced data based on expected values defined by a waveform of the partial response and sampled values obtained by the sampling, wherein:

• frequencies of levels of the sampled values are counted;
• and
• the expected values are provided based on a distribution of the counted frequencies of the levels.

A data reproduction control apparatus performing quantization on a signal reproduced from a recording medium recorded with data in accordance with a given recording code, and controlling a data reproduction characteristic when maximum likelihood detection means, in accordance with a maximum likelihood detection process corresponding to the recording code, determines reproduced data from quantized data obtained by the quantization, the data reproduction control apparatus comprising:

• counting means for counting frequencies of levels of the quantized data;
• and
• characteristic adjustment means for adjusting a processing characteristic in the maximum likelihood detection means based on a distribution of the frequencies of the levels obtained in said counting means.

A data reproduction control apparatus performing, at given intervals, sampling of a signal reproduced from a recording medium recorded with data in accordance with a code of partial response, and determining, in accordance with a Viterbi decoding algorithm, reproduced data based on expected values defined by a waveform of the partial response and sampled values obtained by the sampling, the data reproduction control apparatus comprising:

• counting means for counting frequencies of levels of the sampled values;
• and
• expected value setting means for setting the expected values based on a distribution of the frequencies of the levels obtained in said counting means.

An optical disk unit having a reproduction system including processing means for performing quantization and waveform equalization on a signal reproduced from an optical disk medium recorded with data in accordance with a given recording code, and maximum likelihood detection means for determining, in accordance with a maximum likelihood detection process corresponding to the recording code, reproduced data from waveform-equalized quantized data obtained in the processing means, the optical disk unit comprising:

• counting means for counting frequencies of levels of the quantized data;
• and
• equalization characteristic adjustment means for adjusting a waveform equalization characteristic in the waveform equalization so that a distribution of the frequencies of the levels obtained in said counting means approaches a distribution that should be obtained based on the given recording code.

An optical disk unit having a reproduction system including processing means for performing sampling and waveform equalization on a signal reproduced from an optical disk medium recorded with data in accordance with a code of partial response, and Viterbi detection means for determining, in accordance with a Viterbi decoding algorithm, reproduced data based on expected values defined by a waveform of the partial response and waveform-equalized sampled values obtained in the processing means, the optical disk unit comprising:

• counting means for counting frequencies of levels of the sampled values;
• and
• equalization characteristic adjustment means for adjusting a waveform equalization characteristic in the waveform equalization so that a distribution of the frequencies of the levels obtained in said counting means approaches a distribution that should be obtained based on the code of the partial response.

An optical disk unit having a reproduction system including quantization means for performing quantization on a signal reproduced from an optical disk medium recorded with data in accordance with a given recording code, and maximum likelihood detection means for determining, in accordance with a maximum likelihood detection process corresponding to the recording code, reproduced data from quantized data obtained in said quantization means, the optical disk unit comprising:

• counting means for counting frequencies of levels of the quantized data;
• and
• characteristic adjustment means for adjusting a processing characteristic in the maximum likelihood detection means based on a distribution of the frequencies of the levels obtained in said counting means.

An optical disk unit having a reproduction system including sampling means for sampling, at given intervals, a signal reproduced from an optical disk medium recorded with data in accordance with a code of partial response, and Viterbi detection means for determining, in accordance with a Viterbi decoding algorithm, reproduced data based on expected values defined by a waveform of the partial response and sampled values obtained in the sampling means, the optical disk unit comprising:

• counting means for counting frequencies of levels of the expected values;
• and
• expected value setting means for setting the expected values based on a distribution of the frequencies of the levels obtained in said counting means.