Optical fiber communication system using differential pulse position modulation

Presented herein is a study of an optical fiber communication system for transmission of 7.8 Mb/s signals, by differential pulse position modulation (DPPM). The technological feasibility of a practical system has been clarified by experimental production of the major elements of the system including terminal equipment, repeaters and optical armored cables. Here, the supervisory, control and order wire signals were multiplexed with the main signals by using the features of DPPM. In the modified DPPM, the effect of deterioration on the transmit signal derived from the optical delay distortion was negligible. The reliability of the laser diodes is vital for the entire system reliability. The methods of locating faults in the system, and the laying of cables and other peripheral techniques were also studied.