Bringing International Group, Supergroup, Etc., Links into Service - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 18 pp
Special considerations apply to the use of group and supergroup pilots if circuits are to be provided using Signalling System R2. Group and supergroup pilots placed at 140 Hz from a virtual carrier frequency are incompatible with signalling at 3825 Hz. He