OPTICAL TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical transmission system wherein a subscriber apparatus can inform a station apparatus about its state without being restricted by an assigned data transmission timing.

SOLUTION: The station apparatus 10 and subscriber apparatuses 18-1 to 18-n make communication with each other through a passive optical branching apparatus 14 and optical fibers 16-1 to 16-n. A CPU 24 outputs transmission data to an adder 26 and outputs a state notice signal to a modulator 28. The modulator 28 modulates the output of a local oscillator 30 by using the state notice signal. The adder 26 adds the output of the modulator 28 to the data. An electro/optic converter 32 converts an electric output signal of the adder 26 into an optical signal and its output light is transmitted to the station apparatus 10. A photoelectric converter 46 in the station apparatus 10 converts a received optical signal from an optical fiber 12 into an electric signal. An HPF 48 extracts data signal components from the output of the converter 46. A BPF 50 extracts a subcarrier modulation signal from the output of the converter 46, and a demodulator 52 demodulates the state notice signal from the output of the BPF 50.

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