CHARACTERISTICS OF TOLL TELEPHONE CABLES 



317 



of the resulting product, as well as computing fairly accurately the attenua- 

 tion of all the pairs in a layer by means of the average values of the constants 

 and the departures of the values of the constants of the individual pairs 

 from the average values. Actual attenuation variations of pairs in a reel 



56 

 52 

 4.8 

 44- 



=1 32 



5 



28 



R 



_C 



L 



8 12 16 20 24- 28 32 36 40 44- 4.8 52 56 60 



FREQUENCY - KILOCYCLES 



Fig. 17 — Analysis of variation of attenuation with temperature; variations due to the 

 components R, L, G, C — 19 gauge pairs 



are about ±5 per cent and the standard deviation of the variations is about 

 2.5 per cent. 



Practically, since G/c^C is small, formula (11) may be used in the Taylor 

 series expansion with the variables R/L, LC and RG. This gives the formula 



4a.Aa = ^^ - .Mji/T) + MRG) 



Vl + RVui'L' 



+ co'CVi + i^Vw'^' - i)A(z:c) (15) 



