| 摘要 |
PROBLEM TO BE SOLVED: To improve the recording and reproducing reliability, even in a modulation system without having a DC free characteristic, by setting the cut-off frequency of an AC amplifier for reproducing data low against a frequency that is determined from spacing more than two times the insertion spacing of a re-synchronizing signal. SOLUTION: The detection signal 104 detected by an optical head is amplified by an amplifier 106 through a low frequency cut-off filter 105, and converted into a digital signal 108 by a binarization circuit 107. In the case where the recording code sequence 114 is on the RLL modulation system of ISO standard, a two byte re-synchronizing signal is inserted for example for each data 30-byte. In the digital signal 108, on the the interdiction of the RLL modulation system, the re-synchronizing signal is recognized, with the interval of continuous rise or fall being a specific time or longer. With the amplifier 106 constituted of an AC amplifier, the low frequency cut-off of a low-frequency cut-off filter 105 is set sufficiently low against a frequency corresponding to the re- synchronizing signal interval. |
