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The techniques for predicting total transmission system losses in a fiber optic cable installation involving multiple splices are relatively well known, and significant work has been done in the field of laboratory measurement techniques for quantifying cable (fiber) characteristics and performance characteristics of splices and connectors. The shift of this technology from the laboratory to the actual environment of a field installation, however, poses some significantly different problems to the user of fiber optic cables and splices. The basic instrument available for field use in testing optical links is the Optical-Time-Domain-Reflectometer (OTDR). An OTDR can be used to check the loss profile (dB/km) of a fiber within a cable prior to the cable installation, and to locate installation induced faults in the cable. The capability of the OTDR above to characterize splice losses in an actual installation can be significantly degraded depending on the location of the splice with respect to cable faults, the length of the cable (fiber) run, the characteristics of the individual fibers being spliced, and the ability of the OTDR operator to interpret the-data the instrument is presenting. By following some specific procedures regarding the sequence of installation and testing, and through better understanding of the performance of optical fibers and splices where actually installed in the outside plant environment, installation crews can significantly reduce installation time and time lost because of faults in an individual link that must be reworked. Addi-tional testing with instruments specifically intended for optical power measurement can provide a realistic basis for evaluation of the overall performance of a completely installed link and will give the transmission engineer a solid reference base for use in system set-up in addition to evaluation of system deterioration. Records made through OTDR measurements and optical power instrument readings can be used to quickly locate "accident" faults and evaluate system performance after restoration.
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