Prefix-synchronized run-length-limited sequences

In digital recorders, the coded information is commonly grouped in large blocks, called frames. The authors concentrate on the frame synchronization problem of run-length-limited sequences, or (d, k) sequences. They commence with a brief description of (d , k)-constrained sequences, and proceed with the examination of the channel capacity. It is shown that for certain sync patterns, called repetitive-free sync patterns, the capacity can be formulated in a simple manner as it is solely a function of the (d , k) parameters and the length of the sync pattern. For each forbidden pattern and (d, k) constraints, methods for enumerating constrained sequences are given. Design considerations of schemes for encoding and decoding are addressed. Examples of prefix-synchronized (d, k) codes, based for the purpose of illustration on the sliding-block coding algorithm, are presented