Partial-Response Maximum-Likelihood Channel for Mark Edge Recording on Magneto-Optical Disks

Abstract

We have developed a partial-response maximum-likelihood (PRML) read channel for mark edge recording on magneto-optical disks. In this paper, we report the results of a computer simulation and an actual experiment using this method and compare them with those of a conventional (level slice [bit-by-bit]) detection method in a leading/trailing-edge-independent reproduction. The PRML read channel can decrease the error rates of signal detection in terms of two factors (phase margin characteristics and error rate characteristics of the carrier-to-noise ratio [CNR]). We found that the PR(1, 1) ML detection method improved the CNR by 1.7 dB over the conventional detection method. With these improvements, we achieved a 30% phase margin at a density of 0.57 µm/mark ( 0.43 µm/bit). Therefore, we improved the capacity of MO disks using the PRML read channel, which decreased the error rates of signal detection for mark edge recording.