Enumerative modulation codes based on sliding-window substitutions

We consider high-rate modulation codes satisfying tight global and interleave (G, I) constraints for magnetic storage systems. We use a novel sliding-window substitution coding technique to improve on known long capacity-efficient (G = 2γ, I = γ) codes. This coding technique maps one-sided (G = 2γ, I = γ)-constrained sequences into one-sided sequences satisfying a substantially tighter G constraint and a slightly relaxed I constraint. Sliding-window substitution encoding in conjunction with enumerative encoding provides high-rate capacity-efficient codes that are relevant for practical magnetic storage systems.