High Frequency Standard 197 



A METHOD OF SECURING ACCURATE HIGH 

 FREQUENCY STANDARD. 



R. R. Ramsey, Indiana University. 



In the Trans-Atlantic radio stations of the Radio Corporation of 

 America, Alexanderson alternators are used to generate the high fre- 

 quency current. The frequency of these alternators depends upon the 

 speed of the rotor. This is regulated by automatic devices so the varia- 

 tion is less than two-tenths of a per cent. A recording device registers 

 the speed every minute. 



A radio receiving curcuit containing an oscillating three electrode 

 tube can be tuned until the difference of the frequency of the tube and 

 that of the alternator is some fixed value, for example, the frequency 

 of a standard tuning fork. Then from the frequency of the fork and 

 the speed of the alternator the frequency of the tube or local radio 

 circuit can be obtained. 



These Trans-Atlantic stations operate practically continuously. So 

 the high frequency standard is always available. By arranging in ad- 

 vance the operators of the stations will take special pains to hold the 

 speed constant and will send you the exact speed of the machine cover- 

 ing any particular period. 



'•Proc. 38th Meeting, 1922 (1923). 



