MULTI-SPOT OPTICAL MONITORING CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To increase the distance of transmission and to reduce both configuration scale and price of a device by detecting the transmitting and receiving states of an optical transmission line and arbitrating the receiving operations of monitoring control signals and the transmitting operations of monitoring data. SOLUTION: An NRZ modulation circuit 11 contained in a center device performs the optical NRZ modulation of monitoring control signals to control plural monitoring terminals 43-1 to 43-n. An electrical-to-optical conversion circuit (E/O) 12 converts the modulation output into optical signals and transmits these signals to an optical transmission line 45 via an optical star coupler 13. An optical-to-electrical conversion circuit (O/E) 14 converts the monitoring data of an optical NRZ modulation form transmitted from a certain monitoring terminal via the line 45 and coupler 13 into the electric signals. Then an arbitration circuit 16 detects the transmitting and receiving states of the line 45 and arbitrates the transmitting operations of monitoring control signals and the receiving operations of monitoring data.