A line code called DmB1M that is suitable for a very high-speed, optical, digital-transmission system is described. This code possesses a good balance of marks, spaces, and jitter-suppression capability, as well as a simple in-service error-monitoring function. A fundamental analysis of the DmB1M code is presented, along with experimental results at 1.8 Gb/s. Advantages of this code in parallel signal processing, such as error checking to avoid error propagation, and applications of this code to phase-shift keyed (PSK) systems are also discussed.>

NTT Electrical Communications Laboratories (ECL's) are developing a very large-capacity optical transmission system having information speed on the multigigabit/second order [1]. Equipment design for this system is difficult due to its very large signal bit rate. In the case of terminal equipment, these difficulties are closely related to the line code. This paper discusses a bit insertion code as a high-speed optical line code and its performance. Using this code, a new configuration for the terminal equipment that enables very high-speed signal processing is proposed. This configuration gives the equipment flexibility and numerous advantages in terms of economy.