System Design for the North Atlantic Link

The purpose of this paper is to examine the design and performance of the North Atlantic link, including consideration of factors governing the choice of features, a description of the operational design of the facility, and an outline of those measures available for future application in the event that faults or aging require corrective action. DESCRIPTION OF LINK T h a t portion of the transatlantic system 1 which connects Newfoundland and Scotland consists of a physical 4-wire, repeatered, undersea link of Bell Telephone Laboratories design, with appropriate terminal and power feeding equipment in cable stations at Clarenville and at Oban. The various elements comprising the link are shown in block form in Fig. 1. The termination points at each end of the link are the Group Distributing Frames (GDF), where the working channels are brought down in three groups to the nominal group frequency band 60-108 kc. At the west end, this point provides the interconnection between the North Atlantic and the Newfoundland-Nova Scotia links. At the east end, it is the common point between the North Atlantic link and the standard British toll plant over which the circuits are extended to London. Two separate coaxial cables connect Clarenville with Oban, one handling east-to-west transmission, the other west-to-east. Each is about 1,940 nautical miles long. A total of 102 repeaters are installed in the two cables, at nominal intervals of 37.5 nautical miles. The cables also contain a number of simple undersea equalizers which are needed to bring system performance within the specified objectives.