LOCATION OF OPENS IN TOLL TELEPHONE CABLES 



33 



order to facilitate the use of the curves in locating actual cases of 

 trouble. Where the length of line being measured does not correspond 

 to one of the curve indices, the curves can be interpolated and the 

 desired curve drawn in. 



Fig. 3 — Corrections to be used in finding true position of a fault from the apparent 

 position. Apparent distance to the fault is indicated as a percentage of the total 

 length of the cable. 



The treatment becomes more involved for cables which are not 

 homogeneous. The quads in the outer layers of any unspliced length 

 of cable tend to differ in resistance from pairs in the inner layers, 

 both because of greater length of turn in the outer layers and because 

 of a possible difference in temperature between inner and outer layers. 

 For homogeneous cables treated above these variations in resistance 

 as well as attendant differences in capacitance to ground are equalized 

 by mixing the quads among the various layers at each splice. In 

 general, cables are spliced in this way, although there are several long 

 distance cables now in service which are not homogeneous in this 

 respect. Such cables are spliced in a special arrangement which is 

 essentially a "transposition" system of splicing. 



The "transposed" cable may readily be visualized by a considera- 

 tion of the system of splicing which is employed. Instead of the 19- 

 gauge quads being mixed promiscuously among all the layers, they 

 are divided into an outer layer group and an inner layer group. The 

 quads of each group are mixed among themselves (but not with 

 3 



