| 摘要 |
PURPOSE:To obtain a correct data signal even if level fluctuation exists in a reproduced multi-value signal by providing a means changing plural reference levels in response to a level of a digital signal before one sample period. CONSTITUTION:Four values V0'-V3' of a digital signal fed to an input terminal T1 are fluctuated in response to the level of the digital signal before one sample to four values V0-V3 at recording respectively. The digital signal from an A/D converter 7 is fed to the 1st-3rd comparators 11-13, where they are compared with reference levels E1'-E3' stored in a memory 10. The compared output of the comparators 11-13 is fed to a code converter 14. An output of the code converter 14 is fed to an inhibition circuit 15, the code converting output corresponding to a synchronizing signal VD and a reference signal RVPP is inhibited, and a code converting output corresponding to four values of digital signals DS, that is, only the data signal is outputted to an output terminal T2. Even if the four-value level of the four-value digital signal reproduced in this way is fluctuated through a recording and reproducing system, an accurate data signal is obtained. |
