| 摘要 |
PURPOSE:To attain higher-reliability recording and reproduction when track width is widened by employing a modulation system which is compatible with the modulation system of a PCM signal in high-density recording and reproduction and has longer recording wavelength for recording and reproduction with widened track width. CONSTITUTION:The FM modulation system is employed as the modulation signal of PCM data for high-density recording wherein a tape speed is slow and tracks are formed while overlapping on each other, and the MFM system is employed as the modulation signal of PCM data when the tape speed is increased to widen the track width and guard bands are formed between tracks. When data is decoded during reproduction, attention to the 1st bits of every two bits is paid for both modulation systems to attain the demodulation by a single decoder regardless of the modulation system. Namely, the compatibility is obtained. In this case, the shortest recording wavelength of the FM modulation system is twice as long as that of the FM system. Therefore, this system is advantageous during the recording and reproduction of PCM signals with regard to a dropout, S/N ratio, etc., and highly reliable data is read out. |
