| 摘要 |
PROBLEM TO BE SOLVED: To always enable the reproducing of information with an optimum waveform equalization factor by reproducing information, while setting a waveform equalizing gain so that the difference between the shortest mark length of binarized reproduced signal and the theoretical value of the shortest mark length becomes roughly zero. SOLUTION: A shortest mark detecting means 5 detects the shortest mark length (mean value) in a reproduced signal from a binarizing means, and a means for comparison with theoretical value 6 calculates the difference between the detected shortest mark length and the theoretical value of the length by comparing them. A waveform equalization factor setting means 7 adjusts the difference, varying the waveform equalization factor of a waveform equalizer 4, when the difference is not roughly zero based on a judged result of whether or not the difference between them is roughly zero. When the difference between them becomes roughly zero by repeating such an operation, the means 7 fixes the waveform equalization factor of the equalizer 4 to that value. Then, the reproduced signal from the equalizer 4 is decoded by a decoder 3 and is demodulated by a demodulator.
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