Abstract :
We present a new coding scheme for DC-free runlength-limited (RLL) codes. This scheme is based on the combination of two codes, a main code and a substitution code, both operating on symbols of a fixed length n. The substitution code has a special structure, i.e., for each n-bit symbol, there are two possible channel words, which have opposite parity and the same next-state in the underlying finite-state machine (FSM). The advantages of this systematic structure of the code are: guaranteed DC-control, ECC-symbol oriented coding, and low-complexity look-ahead DC-control encoding. A design for an efficient combi-code for both for EFM-like RLL constraints (d=2, k=10) and for (d=1, k=7) RLL constraints, is outlined
Keywords :
channel coding; runlength codes; DC-free RLL codes; DC-free runlength-limited coding; ECC-symbol oriented coding; EFM-like RLL constraints; FSM; RLL constraints; channel codes; channel words; combi-codes; finite-state machine; fixed length symbols; look-ahead DC-control encoding; low-complexity DC-control encoding; substitution code; Control systems; Frequency; Interference; Laboratories; Low-frequency noise; Merging; Noise level; Optical noise; Optical recording; Servomechanisms;
