| 摘要 |
PURPOSE:To apply a partial response system which makes a precoder unnecessary, to execute binary judgement and to reduce an error rate at the time of high-density recording by carrying out waveform equalization taking the correlation of a modulation signal into consideration. CONSTITUTION:A modified FM signal having such correlation that a code series 0 and 1 is securely followed by 1 and a code series 1 and 0 is securely followed by 0 is utilized. Frequency characteristics of an equalizer 4 are obtained by taking a Fourier-transform ratio of an output signal Y (t) of the equalizer 4 and a reproducing signal z (t) from a record reproducing system 3. Moreover by setting characteristics of the equalizer 4, the response of the entire transmission line summing up the record reproducing system 3 and the equalizer 4 can be made into partial response characteristics. Thus restoration of an MFM signal can be achieved by binary judgement; therefore an error rate of a regenerating signal from an optical disk can be reduced.
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