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THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 



formation lost due to channel noise which is negligible because the error 

 probabihty is low. 



The efficiency graph, Fig. 2, is a chart on which the signal to noise 

 ratio Y in db [computed from Equation (15)] is plotted against the sig- 

 nalling rate per unit bandwidth R/W = (2 log K)/D for different alpha- 



o 

 z 

 \ 



0.5 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 



R/W = RATE PER UNIT BANDWIDTH IN BITS 



5.0 



Fig. 2 — Probability is 10"'' that an error is made in a 10 digit decimal number. 



