SOME APPLICATIONS OF TYPE "J" CARRIER SYSTEM 345 



filters if required as well as the line filters which separate the type J 

 from the non-J circuits. 



A repeater station at Temple could have been located in the existing 

 central ofiice or could be located in a separate building in or near the 

 city. In either case a new power plant was needed since the existing 

 plant could not be economically modified to serve the J carrier repeaters. 

 The telephone line is continuous through the city, only those w^res 

 used for Temple circuits being terminated in the ofiice through one 

 entrance cable 0.6 mile in length. This cable is not suitable for J 

 operation in both directions, which would require one additional cable 

 if the repeaters were located in the central office. Numerous signal 

 and supply lines in proximity with the telephone line within the city 

 off'ered interaction crosstalk complications. A separate repeater 

 station near the toll line in or near the city avoids the placing of a long 

 entrance cable, reduces the overall system attenuation, and eliminates 

 the problem of interaction crosstalk from paralleling lines. Other 

 factors including cost showed very little difference between a separate 

 station and placing the repeaters in the central office. An unattended 

 station near the toll line was indicated. 



A common entrance cable at Dallas terminates the wire on both the 

 Houston and San Antonio lines, the terminal of the Houston line being 

 2.9 miles from the central office, and of the San Antonio line one mile 

 further. This cable previously had been placed in three different 

 sections, each section having a different make-up, and there was 

 considerable doubt as to the number of suitable pairs for J operation 

 that could be obtained. The use of either a loaded or non-loaded 

 spiral-four cable would not improve attenuation sufficiently to change 

 the number or materially alter the locations of the repeater stations 

 from those tentatively selected, but would provide some additional 

 margin for sleet conditions. The expense of loading the spiral-four 

 cable, if placed, could not be justified by the improvement in overall 

 attenuation. Using either non-loaded spiral-four or existing non- 

 loaded paper insulated conductors requires filters at the open-wire 

 terminus. With these considerations, it was decided that suitable 

 pairs would be used in the existing cable until exhausted. Subsequent 

 crosstalk selection tests have indicated that twelve pairs, six for each 

 line, are available. 



Since there was no suitable central office building at Milford, the 

 repeater station in that vicinity must of necessity be in a new building 

 preferably near the toll line. Commercial power is available only near 

 the town, forcing a tentative location to be selected at the edge of the 

 city. 



