TRANSATLANTIC RADIO 'TELEPHONY 



143 



The advantages of this system which had been anticipated, par- 

 ticularly, in respect to economies of power and wave lengths, have 

 been realized. Furthermore, it has been demonstrated that the 

 high-power water-cooled vacuum tubes which have seen their first 

 prolonged operation in this installation are admirably adapted for 

 use in high-power radio installations and particularly for use as high 



Transatlantic Radio Transmission Measurements 



Diurnal Variation of Words Understood 



Feb 25 -April 9, 1925. 



Each circle a average of all tests for that hour including t~- 4* 



triangular points The latter are known to be ewes in whilh r 1ST. It 

 low percentage is due to unnatural cause*. 



power amplifiers, in the type of system we have described. Also, the 

 method of reception has proved itself to be eminently satisfactory for 

 use with the single side-band type of transmission and to possess 

 important advantages for radio telephony in respect to selectivity and 

 amplification. 



Methods have been developed for measuring the strength of the 

 received signals and the strength of the received interfering noise and 

 these methods have been successfully applied in the initiation of a 

 study of the variations to which transatlantic transmission is subject. 



The results of the transmission measurements show that, at 5000 

 meters, the diurnal variations are large, as was to be expected, and 

 give evidences of a large seasonal variation which was, indeed, also to be 

 expected. The results indicate that it will probably be desirable to 

 use a wave length longer than 5000 meters. The measurements are 

 now being made to include the longer wave lengths. 



APPENDIX Added September 23, 1923 

 The results of the transmission measurements from January through 

 August are now available and are summarized in the curves following: 



