OPTICAL FIBER CABLE COMMUNICATION EQUIPMENT

摘要

PURPOSE:To reduce the cost and also to improve the reliability of an optical fiber cable communication equipment by securing such a constitution where the breakage of an optical fiber cable can be detected accurately just by having a double structure of an optical conversion part. CONSTITUTION:Plural pieces of information delivered from a relay device 1 are modulated by plural PCM modulating/demodulating devices 2 and then multiplexed by a multiplexing circuit 3. The output of the circuit 3 is converted into transmission optical signals W1 and W2 by electrooptic converters 4a and 4b having optical outputs of different wavelengths. Then both optical signals are synthesized by a multiplexing circuit 10 and transmitted to a communication equipment 8' of a terminal at the remote side via an optical fiber cable 9 to be separated again into signals W1 and W2 by a demultiplexing circuit 11. These optical signals are converted into electric signals by photoelectric converters 5a and 5b. Here the AND output obtained when the outputs of optical level drop detectors 7a and 7b are used as the double input of an AND circuit 13 is obtained only in case the cable 9 is broken or the double structure and the separation system between converters 4a and 4b as well as 5a and 5b have faults at a time. The probability is very small with the latter case and therefore the breakage of the cable 9 can be detected in the form of an output signal of the circuit 13.