| 摘要 |
PURPOSE:To prevent a received signal from entering a transmission system, by connecting input and output parts of modulator and demodulators and connecting the output part of the reception system and the input and output parts of a modulation and demodulation part through an attenuator. CONSTITUTION:A signal from a modulator and demodulator (MODEM)10 is transmitted to an optical receiver 13 through an optical transmitter and receiver 11 and an optical fiber 12. The received signal is converted into an electric signal 1, which is attenuated by the attenuator 14 and then sent to the MODEM15. The transmission from the MODEM15 to the MODEM10 is performed through an optical transmitter 11', optical fiber 12', optical receiver 13', and attenuator 14'. This constitution eliminates interference even if the input and output part of the MODEM and the input part of the transmitter are connected directly to the output part of the receiver and enables half-duplex two-way coupling. |
