| 摘要 |
PROBLEM TO BE SOLVED: To provide a wobble extracting method and a wobble extracting device capable of more reliably and accurately extracting a wobble signal from a pre-information signal obtained from an optical disk. SOLUTION: An upper limit signal SUL and a lower limit signal SWL, which change levels and limit the levels in response to a signal SL obtained after the pre-information signal SPP passes a LPF(low pass filter) 4 or the wobble signal SB obtained after the signal SPP passes HPF(high pass filter) 5, generated by a limit level generator 2 based on the pre-information signal SPP including the wobble signal SB. A noise signal caused by pre-pits in the pre- information signal SPP is suppressed by a limiter 1 with these limit signals, then the signal SPP is allowed to pass a BPF(band pass filter) 6 to extract the wobble signal SB, which is binarized, thereby obtaining an extraction signal SDTT for controlling the rotation of a DVD-R(digital versatile disk recordable) or a DVD-RW(digital versatile disk rewritable).
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