A 12-Channel Carrier Telephone System for Open-Wire Lines

A new carrier telephone system is described, together with its application in the long-distance telephone plant. By its use, an open-wire pair which already furnishes one voice circuit and three carrier circuits may have 12 more telephone circuits added. Thus in all 16 telephone circuits are obtained on a single pair. Several such systems may be operated on a pole line. Various problems incident to the extension of the frequency range, from about 30 kilocycles, the highest frequency previously used, to above 140 kilocycles, are discussed. Among the more important of these are the control of crosstalk between several systems on a pole line, arrangements for taking care of intermediate and terminal cables, and automatic means for compensating for the effects of weather variations on the transmission over this wide frequency range.