CELTIC Field Trial Results

The CELTIC system (Concentrateur Exploitant les Temps d'Inactivité des Circuits [1], designed to increase the capacity of submarine cable links, was developed in France by CIT-Alcatel under contract with the Centre National d'Etudes des Télécommunications (CNET). CELTIC uses the inactive periods of the circuits to carry additional active circuits.The development of CELTIC led to field trials by the PTT (France) and AT&T (USA) between terminals located at St. Hilaire and Green Hill, RI, respectively. Tests were first conducted with available circuits bridged on the system. In later experiments, 60 additional live circuits, not bridged from primary paths, were added to CELTIC. This paper presents the main results of the field trials and includes a description of the main features of the CELTIC system and of the test conditions, the results of the statistical measurements and system tests, and a survey of CELTIC's subjective performance.