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Partial response modulation codes for electron trapping optical memory (ETOM)

We consider the problem of coding for a recording channel. Traditional magnetic or optical channels employ saturation recording, where the input to the channel is a two-level waveform. New optical recording channels have been developed that support unsaturated, M-ary (M >= 3) signal levels. In this paper we consider the analysis and design of partial response codes for these channels. Comparisons are made with M-ary runlength limited codes. The partial response codes presented here achieve the largest known storage density and achieve a coding gain of 3-6 dB over M-ary runlength limited codes.