SF System: Shore Terminal Facilities and Fault Location

1.1 General Shore terminals at each end of an SF Submarine Cable System provide an interface between the undersea portion of the system and inland transmission facilities. Conventional frequency-division multiplexing techniques are used to translate message signals received from the domestic network to the appropriate frequencies for transmission over the ocean cable; the inverse process is performed on signals received from the cable. The high-frequency portion of the shore terminal provides broadband signal shaping (pre-emphasis) and equalization to optimize the 721 722 T H E BELL SYSTEM TECHNICAL JOURNAL, M A Y - J U N E 1970 signal-to-noise performance of an SF System. Final adjustment of equalization for a particular system takes place after the cable has been laid and its actual transmission characteristic has been determined. Once a submarine cable system is installed, information concerning its performance can be obtained only from measurements made at the shore. Thus, another function of the terminal is to provide means for gathering information necessary for system maintenance and for locating faults that might occur either in cable or repeaters. These functions of the SF Terminal are described in more detail in the sections that follow. Emphasis is placed primarily on those features unique to the SF System and, secondarily, on those features unique to a submarine cable terminal. Generic categories of terminal equipment are as follows: (i) (ii) (Hi) (iv) (v) Multiplex and carrier supply, High-frequency line, Pilot monitoring and measuring circuits, Order-wire, and Maintenance and fault locating test sets.