| 摘要 |
PURPOSE:To lighten the burden imposed on an error detection correcting part by monitoring the run length of a reproduction pulse signal and detecting an abnormality. CONSTITUTION:Information of a recording medium 1 is converted into the corresponding pulse signal PD by a reading part 2, made into bit data DR and a bit clock CP synchronous with the pulse signal PD by a synchronization detection part 3 based on a state change in the signal PD, and supplied to an abnormality detection part 6 and a demodulator 4. The detection part 5 monitors the run length of the pulse PD. When it detects that the run length exists outside of the necessary range and the violation of rules exists, it decides such state to be abnormal, and supplies an error signal to an error detection correcting part 5. In such constitution, the burden imposed on said part is lightened.
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