High-speed voice-frequency carrier telegraph system

C. M. Brentlinger (The Western Union Telegraph Company, New York, N. Y.): The introduction of carriers into the Western Union Telegraph system is a comparatively recent development, and has brought with it some interesting operating problems. Prior to 1929 practically all circuits were operated on physical conductors, utilizing ground-return circuits. With circuits of this type, transpositions in outside wire construction are not necessary, and the wire plant was therefore largely made up of nontransposed conductors and, except for short sections in congested areas, was and is practically all open-wire construction. With the introduction of carrier systems it was, of course, necessary first to do a considerable amount of outside plant work in transposing pairs, eliminating excess resistance, and loading cable sections to obtain suitable pairs for the carrier system. In order to keep the expense for this work at a reasonable minimum, the outside plant work was limited to those pairs actually needed for the carrier systems, so that the carrier leads now contain two or more transposed and balanced pairs for carrier operation, in addition to many wires not transposed and carrying ground-return telegraph circuits of various classifications. In this connection it is interesting to note that while the use of nontransposed wires is generally unsatisfactory in carrier operation, we have in-emergencies successfully bridged breaks in carrier pairs by patching with non-transposed conductors of the same ohmic resistance in lengths up to 50 miles.