| 摘要 |
PROBLEM TO BE SOLVED: To provide an interface for wavelength division multiplexing communication having a function for detecting a trouble occurring in an optical communication system even during operation thereof. SOLUTION: A plurality of single wavelength light source units and an optical multiplexing circuit on the transmission side have a preliminary unit circuit, respectively, and a wavelength multiplexed signal including a preliminary channel signal λ0 is transmitted from an uplink output terminal. On the receiving side, a plurality of optical demultiplexing circuits also have a preliminary unit circuit, respectively, and a received preliminary channel signal λ0 is outputted from a downlink output terminal. The preliminary unit circuit at the transmitting section has a monitor circuit and the downlink output terminal for the preliminary channel signal λ0 is connected with the uplink output terminal for the preliminary channel signal λ0. The preliminary channel signal λ0 passes through the transmitting section, the receiving section and returns back to the transmitting section thus circulating a communication system. Normal circulation of the preliminary channel signal 1 g through the communication system is monitored constantly. |
