hull: transmitter of modulated waves 323 



lasting for a thousandth of a second. Undoubtedly, however, 

 the voltage impacts acting upon the telephones are very much 

 the more intense, though lasting for a shorter time, with the wave 

 train of higher peak value, and it is possible that this is the correct 

 explanation of the louder signal furnished by the logarithmically 

 modulated wave train with simple rectifying detector. If the 

 same power be radiated at long wave-lengths it is quite possible 

 for the peak value of the logarithmically modulated wave train 

 to be so reduced in magnitude that the average value of their 

 square (which is the measure of the output voltage of the de- 

 tector) is equal to or even less than similar values for the sinu- 

 soidally modulated waves. It is likely also that if the wave- 

 lengths of transmission be sufficiently increased the same re- 

 sults in receiving the signals with a rectifying detector can be 

 obtained with the tube transmitter as with a similar spark 

 transmitter. 



In summarizing the foregoing discussion the following essential 

 points appear: (i) It has been found that an electron-tube 

 transmitter operated wholly from an alternating-current source 

 can be made to compare favorably in operating efficiency with 

 a similar transmitter operated from a direct-current source; 

 (2) it possesses the advantage of not requiring a high-voltage 

 battery or generator; (3) the added advantage over a continuous- 

 wave transmitter is that signals may be received over a limited 

 distance with a non-oscillating detector. 



A more complete description of the experiments made in 

 developing this transmitter, and of the theory of its operation 

 will be published at a later date as a Scientific Paper of the 

 Bureau of Standards. 



