Multilevel Block Codes with DC-Constraint Property

Multilevel fixed-length block codes which have a dcconstraint property are discussed, and the upper bounds of the transmission rates of such codes are described under the limitations of the running digital sums (RDS) of coded signal streams. Then stateindependent decodable codes whose transmission rates are equal to the upper bounds are presented for small values of word length. In these codes, four code words or less correspond to a source symbol. As an example, a 5-level code of length 4 whose RDS´s do not exceed 4, whose transimission rate is equal to 2 bits per symbol, and from which good performance for bit timing, gain adjustment of repeaters, and word synchronization can be expected, is also described.