50 



BELL SYSTEM TECHNICAL JOURNAL 



The method of computing type unbalances for far-end crosstalk will 

 now be explained. As in the case of near-end crosstalk, the type 

 unbalance is defined by expressing the far-end crosstalk between two 

 long circuits as the product of the crosstalk coefficient, the frequency 

 in kilocycles and the type unbalance. 



Figure 15B indicates the periodic variation with frequency of the 

 far-end crosstalk when type unbalance is controlling. 



>: 40 



LINE ANGLE IN DEGREES (^D) 

 240 320 400 480 560 



640 



10 15 20 25 30 35 



FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 15 — Type unbalance and crosstalk vs. frequency and line angle in degrees. 

 For Part (5), see Fig. 27.4 for wire configuration and Fig. 28 for transposition 

 types. 



In the case of near-end crosstalk, the method of computing the 

 type unbalance neglected interaction crosstalk since, ordinarily, the 

 transpositions needed to control transverse crosstalk make the inter- 

 action effect negligible. In the case of far-end crosstalk, the most 

 important type of interaction crosstalk is included in calculations of 

 type unbalances but another type of interaction crosstalk and the 

 direct transverse crosstalk are neglected. The transpositions needed 

 to properly suppress the important type of interaction crosstalk and 

 the indirect transverse crosstalk ordinarily make the neglected types 

 of crosstalk very small and the application of a more precise method 

 of computing type unbalances for far-end crosstalk is not justified in 

 practice. 



