OPTICAL INPUT ELECTRIC POWER MONITORING SYSTEM OF OPTICAL REPEATER

PURPOSE:To monitor remotely an optical input electric power of an optical repeater with a simple circuit constitution, by measuring an incident optical power of an optical signal at a DC-DC converter, modulating the thin and dense parts in mark density of a relay digital signal according to the result of measurement and transmitting it to a terminal station. CONSTITUTION:The oscillating frequency of a blocking oscillating circuit 5 in a DC-DC converter 10 is adjusted with an output monitor signal 9 of an optical repeater. The incident optical power of the optical repeater is known by this oscillating frequency. The oscillating frequency is extracted by using a buffer amplifier 8 having a high input impedance. The oscillating pulse voltage of the DC-DC converter 10 detected by the amplifier 8 is led to a modulating circuit 14 via a gate circuit 13. A modulating circuit 14 modulates a pulse signal train of a test signal being an output of a discriminating circuit 11 in response to the said oscillating pulse voltage. The modulation signal is converted into an optical signal at a laser diode 15 and transmitted to a terminal station on an optical fiber 16. The said modulating frequency is detected at the terminal station and the incident optical power of the optical repeater is known.