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BELL SYSTEM TECHNICAL JOURNAL 



is an outline map showing the relative positions of these field receiving 

 stations and the transmitting station. 



The reason for settling down at a fixed point in this way was to 

 attack the problem from a new angle. The field strength survey 

 and aural observations had yielded much interesting information 

 but did not appear at that time to shed a great deal of light on the 

 quality distortion so it was decided to attempt, by an oscillographic 



Fig. 2 — Interior view of test station near Stamford, Conn. 



study of received signals sent out under rigorously controlled con- 

 ditions, to determine just what alterations these signals suffered in 

 their journey through space. 



In finding such distortions the ear is, of course, the primary testing 

 instrument or indicator of trouble, for, if the trained ear is unable to 

 detect anything wrong with a received signal in comparison with its 

 original counterpart it is safe to say that nothing detrimental of import- 

 ance has happened to it. But the ear is a poor quantitative indicator 

 and furnishes no permanent or easily analyzed record of its observa- 

 tions. It is evident that if we are to study quantitatively the char- 

 acteristics of radio transmission which give rise to quality distortion, 



