Construction of simple runlength-limited codes

The authors describe a new technique for constructing fixed-length (d, k) r unlength-limited block codes. The new codes are very close to block-decodab le codes: as decoding of the retrieved sequence can be accomplished by obse rving (part of) the received codeword plus a very small part of the previou s codeword. The basic idea of the new construction is to uniquely represent each source word by a (d. k) sequence with specific predefined properties, and to construct a bridge of beta, 1 less than or equal to beta < d, mergi ng bits between every pair of adjacent words. The new constructions have th e virtue that only one look-up table is required for encoding and decoding.