Jai N. Subrahmanyam

(d, k/T) Constrained Partial Response Maximum Likelihood Codes

A new set of constrained codes, referred to as (d, k/l) constrained partial response maximum likelihood (PRML) codes, is proposed. These new constrained codes combine the benefits of both (d, k) run length limited codes and (0, k/l) PRML codes, with seemingly promising applications in PRML read channels for todays head/media combinations, using thin-film media and inductive read heads. The rules for generating any (d, k/l) code are presented, the Shannon capacity is tabulated for the codes of practical interest with d= 1 and 2, and the encoding finite state transition diagram and state-independent decoder are designed for a rate 1/2, (1, 7/6) code. Some differences among (d, k) codes, (0, k/l) codes, (0, k/l/M) codes and (d, k/l) codes are also addressed.