602 



BELL SYSTEM TECHNICAL JOURNAL 



made ^ on a loop approximately 50 miles in length with repeaters 

 spaced 5 miles apart. The band transmitted extended from 60-2060 

 kc. Fundamental frequencies of 920 and 840 kc. were supplied from 



I \ 

 I I 



-r-r 

 f I 

 / I 

 ( I 



L, 



^^ 



CALCULATED SUM : 



(assuming POWER" 



ADDITION) 

 (assuming VOLTAGE 



addition) 



h^ 



2 4 6 8 10 12 14 16 18 20 



NUMBER OF AMPLIFIERS ( n) 



Fig. 3 — Experimental data on addition of third order modulation from a multi- 

 repeater line. Fundamental test tones A = 920 kc, B = 840 kc. Modulation 

 product 2A-B = 1000 kc. 



two oscillators at the sending end, and measurements with a portable 



current analyzer were made at each repeater to determine the ratio of 



^ Messrs. M. E. Campbell and W. H. Tidd collaborated in these measurements. 



