New military carrier telephone systems

Military communication systems have recently been developed for operation in tactical areas using carrier telephone channels on spiral-4 cable. This is part of an extensive program intended to increase the flexibility of the military communications network. Good transmission performance under all environmental conditions has been stressed. These projects make use of a new type of spiral-4 cable. The cable is to be laid in 1/4-mile lengths with or without loading coils at the junctions. A 4-channel telephone system using the carrier frequency range from 4 to 20 kc has been designed for operation on the loaded cable for distances of 100 miles with repeaters at about 25-mile intervals. A 12-channel telephone system using the carrier frequency range from 12 to 68 kc has also been designed for operation on the nonloaded cable for distances of 200 miles with main repeaters at about 40-mile intervals and with “power-over-the-cable” repeaters at about 6-mile intervals. These new low-loss channels make possible the use of multilink connections and the ultimate establishment of a comprehensive military communication network. The circuits have been developed for great reliability, with simple operating procedures, automatic alarms, good maintenance practices, and great flexibility as to usage.