Some Applications of the Type 'J' Carrier System

T W E L V E - C H A N N E L carrier telephone system for open-wire lines was described before the American Institute of Electrical Engineers early this year,1 and a discussion of the requirements of line facilities for its operation is being presented.2 Since the first three systems to be placed in commercial operation are located in Texas, it seems appropriate to present to the Southwest District Convention the major problems arising from the practical application of this type system on existing open-wire plant. In 1935 it became apparent that existing open-wire facilities on some of the major toll lines in Texas would soon be exhausted. In the case of the Dallas-Houston, Dallas-San Antonio, and Dallas-Longview lines, current growth and requirements for the future indicated that while a toll cable would probably have to be provided ultimately, the development of the open-wire twelve-channel J carrier system makes available an arrangement for obtaining a large number of additional circuits over the existing lines to provide for the immediate requirements and also permit postponement of more costly relief measures for a number of years. The type J system operates in a frequency range above that of the three-channel type C carrier system and can be superposed on the same conductors with the type C, thereby providing a total of sixteen circuits from one pair of conductors. However, conductors suitable * Presented April 18. 1939 before the A . I . E . E . in Houston. Texas. "A Twelve-Channel Carrier Telephone Svsteni for Open Wire Lines," by B.