ABSTRACTS OF TECHNICAL ARTICLES 543 



found for the dynamically measured piezoelectric constants from 

 those statically measured, which may be attributed to the finite relaxa- 

 tion time for the piezoelectric elements. 



A Vo gad for Radio Telephone Circuits. ^"^ S. B. Wright, S. Dob a, 

 and A. C. Dickieson. Commercial radio telephone connections must 

 generally be accessible to any telephone in an extensive wire system. 

 Speech signals delivered to the radio terminals for transmission to 

 distant points vary widely in amplitude due to the characteristics of 

 the wire circuits and individual voices. To provide the best margin 

 against atmospheric noise, it is usually the practice to equalize this 

 wide range of speech amplitudes and thus drive the radio telephone 

 transmitter at its full capacity. 



Many devices have been proposed to adjust automatically the gain 

 in a circuit to equalize speech volumes. The difficulties of providing 

 a device which will respond properly over a wide range to the complex 

 qualities of a speech signal have only recently been overcome to a 

 satisfactory degree. 



The voice-operated gain-adjusting device, or "vogad," described 

 in this paper is a practical design based upon more than a year's 

 experience with one of the most promising devices made available by 

 earlier development effort. A trial installation of this latest vogad is 

 now under way at Norfolk in connection with a new radio telephone 

 system for harbor and coastal service. 

 12 Proc. I. R. E., April 1939. 



