OPTICAL FIBER TRANSMISSION SYSTEM

摘要

PURPOSE:To avoid the stoppage of the signals in case the optical fiber is cut off by installing the means which receives the clockwise and counterclockwise optical signals plus the means which can perform the clockwise and counterclockwise transmission of the optical signals respectively to the end offices combined circularly to each other. CONSTITUTION:Center station optical directional couplers 5 and 6 of center station 4 are connected to circular optical fiber 8, and plural number of end office optical directional coupler 7 is connected to fiber 8 each. Then six units of input/ output terminals (a)-(f) are provided to coupler 7 to receive the optical signal of clockwise direction A and that of counterclockwise direction A' from fiber 8 via optical switch 12, and either of the both signals is supplied to photo detector 14. And the optical signal sent from light emitting element 15 can be transferred to fiber 8 in both directions A and A' via optical switch 16. The optical signals of both directions A and A' are transmitted via coupler 5 of station 4, and the optical signal in direction A or A' can be received via coupler 6.