| 摘要 |
PURPOSE:To simplify the circuit configuration without giving effect onto a main signal circuit and a bit rate by arranging an exclusive optical fiber and an optical filing amplifier for a monitor control signal use in addition to an optical fiber and an optical filing amplifier for sending a main signal. CONSTITUTION:An optical branching device 30 in an optical filing amplifier branches a monitor control signal output into two, a photodetector 33 applies photoelectric conversion to a monitor control signal for its own repeater and the result is inputted to a monitor control circuit 34. The circuit 34 outputs an oscillating frequency setting signal varying an oscillating frequency of an oscillator 32 in response to a monitor voltage applied as a monitor signal. Then the oscillator 32 modulates a pumping light source 31 to apply amplitude modulation to the monitor control signal and the result is sent to a next stage terminal station. Since the transmission frequency is selected freely, the system is monitored without giving effect onto the in-service state of the main signal to simplify the circuit configuration. |
