| 摘要 |
PURPOSE:To demodulate code data into playback data accurately by varying the frequency range of pulses for reproduction which synchronize with reference pulses according with the variation of the reference pulses, putting the code data in phase with the pulses for reproduction, and comparing the pulses for reproduction with the reference pulses and deciding whether or not they shift in frequency from each other. CONSTITUTION:A control circuit 15 judges a track range which includes a target block number and clock speed information, performs arithmetic operation according to data within the track range, and calculates the track number and start sector of the target block on the basis of the arithmetic result. A programmable synthesizer 23 generates the reference pulses of time width corresponding to the block speed information supplied from the control circuit 15 and supplies them to a converting circuit 20 and a demodulation part 14. A playback code output circuit 38 outputs the code data to a demodulating circuit 35 by using the pulses for reproduction from a voltage-controlled oscillation circuit 35 and the demodulating circuit 36 demodulates the converted code by reconversion and outputs the demodulated playback data to the control circuit 15. Consequently, the code data are demodulated into invariably accurate playback data.
|
