SG Undersea Cable System: Commissioning: Final System Alignment and Evaluation

Commissioning, a British Post Office term, is the test and adjustment program (or process) performed on a newly installed undersea cable link before it is placed in service. The cable system is measured and aligned, and its performance is optimized. This process starts during installation and continues until the terminal-to-terminal link is ready to be released for service. The bulk of the effort takes place after cable laying 1 is finished; that is, after the final splice, and can take several weeks to complete. This paper describes the commissioning process for the SG system. General descriptions of the test program and illustrative data from the TAT-6 link are provided. Fault localization reference data, although part of commissioning, are not discussed. Successful completion of commissioning means that the cable and 2547 terminal transmission equipment (supergroup-to-supergroup) are equalized, signal-to-noise ratio is optimized over the transmission bands, and the terminal equipment is adjusted so that service may begin. Accurate commissioning test data are vitally important because these data are used also to: (i) Determine link operating performance. (ii) Compare actual with computed performance. (iii) Provide initial data so that future link performance may be evaluated. (iu) Obtain reference data for maintenance purposes. Incidentally, the SG system differs from the SF and SD systems 2 - 3 in that the undersea link transmission can be adjusted from the terminal, by means of shore-controlled equalizers.