5 RUNLENGTH-LIMITED CODES FOR M-ARY RECORDING CHANNELS

This paper is concerned with M-ary runlength-limited (RLL) codes for n onbinary recording channels, The codes have fixed-rate finite state en coders, sliding block decoders, and large coding density. Five codes a re given achieving coding densities of 24 bit/minimum-recorded-mark as compared with 1-1.5 for binary recording channels, The codes are 93-9 8.5% efficient and either achieve or come close to achieving the fewes t number of encoder states possible, One of these codes has been imple mented in a prototype system that supports M=6 discrete recording leve ls.