A simple detection method for RLL codes (Run detector) [magneto-optical disk systems]

In Magneto-Optical (MO) disk systems, the conventional edge detection method with a run-length limited (RLL) code has the limitation of detection of recorded bits at linear densities where the carrier level of the minimum mark length is small, because of increasing inter-symbol interference (ISI). We propose a new detection scheme which has performance as good as the conventional Viterbi detector and which yields good detection quality for such ISI. Stable detection is realized by detecting prohibited run-length codes and adjusting the decision algorithm to disk recording characteristics. The proposed detection scheme is effective at high linear densities and with tilt phenomena, and this circuit is much smaller than that of the Viterbi detector.