摘要 |
A communications connection comprises intermediate connection points (6,11) connected by a non-conducting communications link (20), with conversion equipment in one or both intermediate points for converting communications between electrical and non-electrical carriers, and each being arranged to be powered from the respective ends (1, 12). If a metallic path (18) is present between the two intermediate points, the system can be arranged to use this for a limited connection service in the event of loss of electrical power to one or both of the intermediate points (6,11). |