RECORDING/REPRODUCING METHOD FOR MULTIVALUED SIGNAL

摘要

PURPOSE:To reproduce a multivalued signal out of a data recording area by detecting the group displacement value and the group length based on the transition level and the transition timing. CONSTITUTION:A synchronizing signal and an amplitude reference signal consisting of the maximum and minimum values of multivalued signal are applied to a data recording area. Then a synchronizing signal is obtained by means of the light quantity of a reflected light beam L2 received from an optical disk 2. The beam L2 is received by a 2-split optical detector 10, and the amplitude reference signal is reproduced with use of a difference signal SPP between output signals SPD1 and SPD2. Then a transition level is set with use of the maximum and minimum values of the multivalued signal. Furthermore the signal SPP is differentiated in two steps for detection of the transition timing. The group displacement value and the group length of the disk 2 are detected based on the transition level and the transition timing. Thus the multivalued signal is surely reproduced out of a data recording area.