Patent ID: 7092328

Claim:
An information storage medium comprising: a wobble track having a wobble period that is modulated by multi-frequency shift keying corresponding to playback control information containing address data and header data, the header data including a VFO (Variable Frequency Oscillator) area formed from a predetermined frequency, and frequencies contained in the multi-frequency shift keying satisfy orthogonal conditions, wherein a minimum time interval for which the frequencies satisfy the orthogonal conditions is defined as Ts, wherein a time interval for which a symbol that indicates the playback control information changes is defined as Tw, wherein the VFO area is formed from the highest frequency contained in the multi-frequency shift keying, and wherein the symbol is configured to be demodulated by an information playback apparatus comprising (i) a plurality of narrow bandpass filters corresponding to the frequencies contained in the multi-frequency shift keying, (ii) a timing detection section configured to integrate over the time Tw a difference between the wobbled signal and a delayed wobbled signal, which is obtained by delaying the wobbled signal by the time Ts, and to detect a switching timing of the symbol that indicates the playback control information based on an integration result, (iii) a selection section configured to select a wobbled signal having the highest signal intensity from a plurality of wobbled signals output through the plurality of narrow bandpass filters based on the timing detected by the timing detection section, and (iv) a symbol demodulation section configured to demodulate the symbol from the wobbled signal selected by the selection section.