| 摘要 |
PURPOSE:To judge the reliability of demodulated data, by performing demodulation by using the relative value of a reproduction signal level by a differential detection means, and detecting the absolute value level of the reproduction signal. CONSTITUTION:The differential detection means 23 which detects the reproduction signal level from a recording medium and performs the demodulation by using the absolute value level of the reproduction signal, and level detection means 25A and 25B which compare the reproduction signal level from the recording medium with a reference level set in advance and detects the absolute value level of the reproduction signal are provided. Thereby, the demodulation is performed by using the relative value level of the reproduction signal level by the differential detection means 23, and also, the absolute value level of the reproduction signal is detected. In other words, our positions where the relative value levels of a reproduced RF signal are high are detected, and the data is demodulated from a position number, and the absolute value level of the reproduced RF signal is detected. and the reliability of the demodulated data is judged from the absolute value level.
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