SOLDERLESS WRAPPED CONNECTIONS PART III 609 



probably have a central office life of more than fifty years without de- 

 veloping objectionable resistance variation. Tests on other terminals 

 and using wires heavier than No. 20 and on wires smaller than No. 24 

 are to be made. 



ACKNOWLEDGEMENT 



The author acknowledges that this paper reflects largely work done 

 under the supervision of D. H. Gleason whose recent retirement pre- 

 vented his authorship. 



Appendix A 



NOISE LEVEL ARISING FROM VARIABLE CONTACT RESISTANCE 



The measurement of contact resistance noise in a telephone central 

 office has been standardized, and the estimate of the effect of a given 

 resistance variation has been made in accordance with the standard 

 technique. 



In this measurement, a 2-B noise measuring set is connected as shown 

 in Fig. 13 (a) where the voltage, e, is that due to a variation in contact 

 or connection resistance. If a dc current i is flowing and the resistance 

 variation is (A/^)o sin w^, then 



ee„= ^J-(A/i!) (1) 



and 



F^ = I e. (2) 



In the subscriber condition (Fig. 13 (b)) there is a 3 db loss in the 

 subscriber's loop and a 3 db loss at the subset so that the voltage at the 

 receiver 



and 



It therefore follows that 





A 



2e ^ 1 ^8 

 Vr 3*4^ 3 



