Wobble demodulator and wobble demodulation method

A wobble demodulator for reproducing digital information from an optical recording medium in which a track, for recording data in accordance with a wobble signal modulated so as to represent digital information by a combination of a modulation signal that is frequency-modulated or phase-modulated and a carrier signal that is not frequency-modulated or phase-modulated, is wobbled to be formed, comprising:

• a wobble signal detector for detecting a wobble signal in accordance with wobbling of the track from the optical recording medium;
• a wobble PLL for detecting the carrier signal based on the wobble signal detected by the wobble signal detector;
• a PLL lock determiner for detecting a lock state of a PLL representing a synchronization state in a frequency and a phase between the wobble signal and the carrier signal;
• and
• a decoder for reproducing address information by decoding the wobble signal detected by the wobble signal detector and the carrier signal detected by the wobble PLL in accordance with a detection result of the PLL lock determiner,
• wherein the decoder is operated so as to detect and lock a synchronization position with respect to the digital information when the PLL lock determiner detects a PLL lock, and is operated so as to unlock the locked synchronization position when the PLL lock determiner detects a PLL unlock.

A wobble demodulation method for reproducing digital information from an optical recording medium in which a track is formed in accordance with a wobble signal that is MSK-modulated so as to contain the digital information by a carrier signal with a predetermined frequency and a sine wave signal with a frequency different from that of the carrier signal, comprising:

• detecting a wobble signal of the track from the optical recording medium;
• detecting the carrier signal based on the wobble signal detected by the detection of the wobble signal;
• multiplying the carrier signal detected by the detection of the carrier signal by the wobble signal detected by the detection of the wobble signal and outputting a multiplied output;
• detecting a MSK modulation mark having a phase or a frequency different from that of the carrier signal, based on an integrated value obtained by integrating the multiplied output in the multiplication on a predetermined section basis;
• and
• detecting a synchronization position with respect to the digital information, based on the MSK modulation mark detected in the detection of the MSK,
• wherein in the detection of the synchronization position, a continuous predetermined number of absolute values of the integrated values are compared with a first threshold value for detecting a central portion of the MSK modulation mark, a second threshold value for detecting leading and trailing edges of the MSK modulation mark, and a third threshold value for detecting non-modulated portions before and after the MSK modulation mark, and detects the MSK modulation mark based on a pattern of a comparison result.

A wobble demodulation method for reproducing digital information from an optical recording medium in which a track, for recording data in accordance with a wobble signal modulated so as to represent digital information by a combination of a modulation signal that is frequency-modulated or phase-modulated and a carrier signal that is not frequency-modulated or phase-modulated, is wobbled to be formed, comprising:

• detecting a wobble signal in accordance with wobbling of the track from the optical recording medium;
• detecting the carrier signal based on the wobble signal detected in the detection of the wobble signal;
• detecting a lock state of a PLL representing a synchronization state in a frequency and a phase between the wobble signal and the carrier signal;
• and
• reproducing address information by decoding the wobble signal detected in the detection of the wobble signal and the carrier signal detected in the detection of the carrier signal in accordance with a detection result in the determination of the PLL lock,
• wherein the decoding is performed so as to detect and lock a synchronization position with respect to the digital information when a PLL lock is detected in the determination of the PLL lock, and is performed so as to unlock the locked synchronization position when a PLL unlock is detected in the determination of the PLL lock.