Some Applications of the Type "J'^ Carrier System* 



By L. C. STARBIRD and J. D. MATfflS 



Previous papers before the American Institute of Electrical 

 Engineers describe the development of a twelve-channel type J 

 Carrier System. This paper discusses some of the practical 

 problems encountered in extending the circuit capacity of existing 

 open-wire lines by the use of this carrier system. 



The first systems of this type were placed in commercial opera- 

 tion late in 1938. One of these systems is discussed in detail from 

 the standpoint of obtaining satisfactory operation with the most 

 economical arrangement of new and existing facilities. 



A TWELVE-CHANNEL carrier telephone system for open-wire 

 -*- ^ lines was described before the American Institute of Electrical 

 Engineers early this year/ and a discussion of the requirements of hne 

 facilities for its operation is being presented.^ 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 develop- 

 ment 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 Hcuston. Texas. 



^ "A Twelv^e-Channel Carrier Telephone Svstem for Open Wire Lines," by B. W. 

 Kendall and H. A. Affel, Winter Convention, A.I.E.E., 1939. Bell System Technical 

 Journal, Januarv 1939. 



2 "Line Problems in the Development of the Twelve-Channel Open-Wire Carrier 

 System," by L. M. Ilgenfritz, R. N. Hunter, and A. L. Whitman, District Convention, 

 A.I.E.E., Houston, 1939. This issue of the Bell System Technical Journal. 



338 



