The application of the optical fiber transmission for industrial remote-control network, especially in electric power industry, is one of the major applications of the optical fiber communication technology, because of its noise immunity characteristics. An aerially installed optical fiber cable test link of 2 km long was constructed between two office buildings in downtown Osaka, to examine such potentiality. The link has a transmission capability of frequency-division-multiplexed (FDM) telephone signal of 600 channels, using pulse-interval-modulation (PIM) method. Various data on the transmission quality and the long term stability of the transmission characteristics against the environmental conditions have been accumulated since February 1976, using the test link. Although the environmental conditions of an aerial link is much severer than that of an underground link, the system has been working satisfactorily so far. But variation of transmission loss up to 1 dB corresponding to the ambient temperature variation is observed in the particular fiber lines. The major portion of the variation was confirmed to be attributable not to fibers but to splices, through simulating experiments.
© 1977 Optical Society of AmericaPDF Article