384 BELL SYSTEM TECHNICAL JOURNAL 



at the center and when all tertiary circuits are continuous at the 

 transposition point and terminated at the ends. Curve {AB + A'B') 

 gives the results when the two sections are combined with no trans- 

 position. Curve (AB — A'B') shows the result when a transformer 

 is inserted in one coaxial at the junction. (A similar set of curves is 

 given for BA, B'A', etc.) 



It is seen that in the 50-200 kc range there is an improvement in 

 overall crosstalk of from 3 to 8 db due to the transposition. However, 

 the overall crosstalk in the combined sections with a transposition is 

 not appreciably less than that in an individual 12,000-foot section as 

 shown by curve Fi on Fig. 8. Reference to Fig. 11 shows that this is 

 due mainly to the far-end far-end interaction crosstalk between the 

 two sections which is unaffected by the transposition. 



The results shown in Fig. 12 give some indication of the extent to 

 which far-end crosstalk may be reduced by means of a transposition, 

 provided interaction crosstalk between sections is entirely suppressed. 

 As illustrated in Figs. 13 and 14 a transposition at a repeater point is 

 not nearly so effective if the interaction crosstalk is not suppressed. 



Acknowledgment 



The authors are greatly indebted to Mr. John Stalker and the staff 

 at the Princeton, New Jersey, repeater station of the American Tele- 

 phone and Telegraph Company and to Mr. William Bresley and Mr. 

 Norman Mathew of the New Jersey Bell Telephone Company, for their 

 cooperation and assistance in the Princeton tests. 



