Abstract

We consider tradeoffs and storage density limitations in both binary and M-ary optical recording systems that use runlength limited coding. The intention of M-ary recording is to increase the storage density and/or data transfer rate of the disc. However, for a given increase in channel signal-to-noise ratio, it is not clear whether binary coding methods or M-ary coding methods achieve the largest density. In this paper we give fundamental insight to this problem. Particular emphasis is given to the best choice of M, the number of recording levels, and the runlength parameters d and k for a given channel signal-to noise ratio to maximize storage density. The storage channel is assumed to be noisy with an additive white Gaussian noise. The Shannon capacity (and maximum storage density) is discussed and computed for various signal to noise ratios and recording parameters.

© 1998 Optical Society of America