A STUDY OF ASYMMETRY COMPENSATION FOR PARTIAL-RESPONSE MAXIMUM-LIKELIHOOD DETECTION IN OPTICAL-RECORDING MEDIA

The partial-response maximum-likelihood (PRML) detection technique is effective for high-density recording media. In the field of magnetoopt ical recording media, it is mainly adopted in a magnetic field modulat ion recording system. For a light intensity modulation (LIM) recording system, however, signal asymmetry caused by the deviation From the op timum recording conditions easily deteriorates the PRML detection proc edure. In this paper, we propose an ''adaptive reference level techniq ue'', which can greatly improve the write power tolerance. It is expec ted to suppress the influence of the signal asymmetry in the LIM recor ding system.