.3<y) 



HULL SYSTEM LECLIMCAL JOl'RS'AL 



prtjperly l)alaiu'(.'il iidsslalk belwccn circuits will resiiil. The ftTects 

 of capacity uni)alaiices of this kind are particularly serious in pro- 

 ducing side to side and phantom to side crosstalk in quadded cable 

 circuits unless great care is taken in splicing the various pairs and 

 quads in consecutive lengths so that the resultant unbalances will be 

 a minimuni. This is to be expected since in cables the electrostatic 

 capacities between conductors and between conductors and sheath 



are lii,t;h as conipartd to open wire cinuits and an\- irregularities in 

 construction ma>' i^roduce \er\- aiijireciable unlialance conditions 

 between these capacities. 



Fig. 12 shows the direct electrostatic capacities in a ciuad which, 

 if the>- do not have the proper balance relations will produce ex- 

 cessive crosstalk. The conductors of one pair are designated "white" 

 and "white mate" and of the other pair "black" and "black mate." 

 The particular arrangement of the conductors in the figure to form 

 the arms of a Wlieatstone bridge is used since this arrangement is 

 employed in the capacity unbalance measuring circuit described later. 



Neglecting second order effects, side to side crosstalk is prfxluced 

 b\- unbalances in the direct rapacities between conductors in ac- 

 cord, iiuc will) ihe loilowiiig it'lalion. 



C'apacitN unl),ii,ince= Ci + G— (C2-I-C4). 



In i)hanloni lo si(U' crosstalk the imbalance relations of liie direct 

 capacities of liie condiiclors lo gromid (sheath and "bmuli '1 in ad- 

 dition to llu' direct capacities between conductors become imi)ortant. 

 Again neglecting second order elTects. llu' imbalance relations pro- 

 ducing cros>l,ilk Ix'lwern ihe ph.mloni .md llie "while" side is 



Capacity imbai.ince = 2 [(^'1 + <^'.; - l<-'.i-(-C'4) -|-^. ( fir- Cmi/))- 



