ABSTRACTS OF TECHNICAL PAPERS 751 



were met and solved in the course of the development of commercial 

 transatlantic telephony. The discussion covers the use of single side 

 band transmission, directive receiving antennae and voice-operated 

 relays which permit of two-way operation upon a single wave-length. 

 The possibilities brought to light by the extended study of receiving 

 conditions are also described. 



Some Possibilities and Limitations in Common Frequency Broad- 

 casting.^ DeLoss K. Martin, Glenn D. Gillett, Isabel S. Bemis. 

 Radio broadcast stations assigned to transmit on the same carrier 

 frequency may cause audible beat notes to be produced when their 

 signals are received simultaneously, due to the inaccuracies in the 

 frequency adjustments of the transmitters. The radio broadcast 

 transmission results that might be obtained from two or more stations 

 transmitting on the same frequency with sufficient accuracy in fre- 

 quency adjustment to eliminate audio-frequency beat notes are 

 presented briefly in this paper. 



Two cases are considered, the first case where there is a difference 

 in frequency of a few cycles and the second case where the frequency 

 of the carrier signal for all stations transmitting on the same frequency 

 is determined by a common oscillator. 



The results of preliminary experimental tests with the signals 

 from a station in New York City and a station in Washington, D. C., 

 are given. 



^ Proceeding Institute of Radio Engineers, \o\. 15, Number 3, p. 213, March, 1927 



