APPLYING CARRIER TELEPHONE SYSTEMS 551 



intended for carrier operation. As has been described previously in a 

 paper in this Journal ^ the crosstalk mitigation plans in connection 

 with type K carrier are designed on the assumption that cable pairs 

 will be developed in units of 20 pairs for each direction of transmission. 

 Further, the design of this carrier system contemplates the use of 

 19-gauge pairs. 



Ten quads (20 pairs) were, therefore, selected in each cable in which 

 carrier operation was planned. These quads were selected, for cross- 

 talk reasons, from a large voice complement. Two-wire facilities may 

 be used for carrier where a sufficiently large complement exists. This 

 results, however, in the loss of twice as many voice circuits as com- 

 pared to unloading four-wire quads. In the sections unloaded to date 

 it has been impracticable to unload two-wire facilities. 



Where four-wire facilities were used, five quads from the groups 

 designed for each direction of voice frequency transmission in each 

 cable were selected. Over 20,000 circuit miles of four-wire facilities 

 have been unloaded for carrier use. Of this total, H-174-63 loading 

 units were removed from 2,280 circuit miles, and H-44-25 units were 

 removed from the remainder. The H-44-25 loading units removed 

 from 2,475 miles of four- wire circuits were transferred to two-wire 

 16-gauge quads loaded with H-174-63 units in the same cable, and 

 these latter units released, thus providing at small cost transmission 

 improvement on a total of 4,950 circuit miles. 



Preparation of Cable Conductors 



Coincidentally with the removal of the loading from the quads 

 selected for carrier operation, special splicing work was performed for 

 crosstalk and transmission reasons. The exact method of making 

 these splices depended upon the layup of the cable involved. For 

 example, if the cable involved concentric segregation, the five former 

 east bound quads were spliced at random to the five former west bound 

 quads and vice versa at each loading point; in cables involving split 

 layer segregation, the ten quads were spliced at each loading point in 

 a planned random manner. 



The removal of the loading at the point nearest the center of each 

 carrier repeater section was left until last, so that a special splice, 

 called a poling splice, based on measurements of within-quad admit- 

 tance unbalances, might be made at each such point. ^ These meas- 

 urements could not be made until all loading coils on the carrier pairs 

 in the repeater section had been removed. Using these measurements 

 as a guide the quads in one half-section were connected to quads in 



