SAFETY SHUTDOWN SYSTEM FOR A WDM FIBER OPTIC COMMUNICATIONS SYSTEMS

摘要

A fiber optic communications network includes multiple transmitters andmultiple receivers connected by an optical WDM transmission link, thereceivershaving output channels for providing signals to terminal devices, eachreceiverincluding a demodulator to detect and recover a received signal, and thenetworkincludes at least one optical amplifier having a shutdown input for actuatingthesafety shut down of the network upon detecting a disconnect in thetransmission line.The system includes circuitry connected to the output of each of thedemodulatorsfor sensing the presence of a valid signal and for determining whether apredetermined number of valid signals are present at the demodulators. If thenumber of valid signals detected is less than the predetermined majoritynumber, thesafety shutdown function is actuated.