CROSSTALK AND NOISE FEATURES 



153 



For economic reasons it is undesirable to install a complete panel 

 for the ultimate number of pairs, possibly 100 in some cases, but rather 

 to install sections conforming more closely to the circuit growth. 

 The placing at different times and properly connecting of sections ob- 

 tained from the 100-pair criss-cross panel and at the same time main- 

 taining service on operating circuits appeared rather formidable. This 

 problem was solved by the use of two types of criss-cross panels; an 



4-6 .2-4 1-2 



1-2 1-3 3-5 5-7 7-9 9-11 11-13 13-15 i5-l7 17-19 



BALANCING POSITION FOR PAIR COMBINATION INDICATED 



Fig. 11 — Schematic of criss-cross wiring for 20-pair balancing panel, designed to 

 maintain phase equality of coils. 



intra-group panel for balancing within one group of carrier pairs and an 

 inter-group panel for balancing pairs in one group against pairs in a 

 second group of equal size. In the present design, an intra-group 

 panel takes care of 20 pairs (190 combinations) and an inter-group panel 

 of the 400 combinations between two 20-pair groups. To maintain 

 phase equality through a number of panels, it is necessary to install 

 them following a definite pattern. Figure 12 shows a suitable pattern 

 for the 15 panels required for 100 pairs. 



