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BELL SYSTEM TECHNICAL JOURNAL 



circuits such, for example, as points where circuits branch off the line. 

 Transposition arrangements must be chosen for each circuit in each 

 type of section to ensure this approximate crosstalk balance. 



Fig. 28 — Fundamental types for 32 transposition poles. 



Certain lines have few, if any, discontinuities and a succession of the 

 longest type of section is used. To improve the effectiveness of the 

 transpositions, junction transpositions are used at the junctions of 

 successive similar sections. For such lines it would be more effective 

 to use longer transposition sections and not require that all circuits be 

 approximately balanced in a short length. Such a special design 

 would be impracticable, however, since it would be too inflexible in 

 regard to circuit changes, etc. 



In choosing the transposition arrangements for a section it must 

 be kept in mind that the object is to meet certain crosstalk limits for 

 a succession of sections considering both type unbalance and irregu- 

 larity crosstalk. The method of procedure is discussed below. 



