OPEN-WIRE CROSSTALK 



51 



The far-end type unbalance for a non-transposed part of a long 

 parallel between two circuits will be computed first. Such a part of 

 a parallel is indicated by length D of Fig. 16. For purposes of compu- 

 tation this length is divided up into a number of short segments each 

 of length d. Considering the far-end crosstalk for two such segments 

 at the start of the length D it will be seen from the discussion of 

 crosstalk coefficients that transverse crosstalk in the length 2d will be 



IFKd = 2{Fd + Fi)Kd. 



In the above expression F is the far-end crosstalk coefficient, Fa being 

 that part due to direct crosstalk and Fi that part due to indirect 

 crosstalk. 





TO LONG 



circuits" 



Fig. 16 — Far-end crosstalk between untransposed circuits in length D. 



The above expression relates to the output-to-output crosstalk. 

 The input-to-output crosstalk is obtained by multiplying by the 

 propagation factor e"^^"' to allow for propagation from A to C. This 

 correction is usually made only when it is desired to obtain the input- 

 to-output crosstalk between complete circuits and it is usually satis- 

 factory to correct by using the attenuation factor and ignoring change 

 in phase. 



The total transverse output-to-output crosstalk in the length D is: 



{Fa + Fi)KD. 

 This is about equal to FiKD since Fd is ordinarily small compared to Fi. 



