TRANSATLANTIC RADIO TELEPHONY 117 



was used in connection with the receiving set, instead of head receivers. 

 The reporters present easily made a transcription of all the remarks, 

 both with head sets and with the loud speaker. 



These tests were made possible by cooperation between the engineers 

 of the American Telephone and Telegraph Company and the Western 

 Electric Company, and the engineers of the Radio Corporation of 

 America and its associated companies. The sending apparatus was 

 installed in the station of the Radio Corporation of America, at 

 Rocky Point, L. I., in order to make use of that company's very 

 efficient multiple-tuned antenna. The receiving apparatus was 

 installed in the buildings of the Western Electric Company, Ltd., 

 at New Southgate, England. 



This was not the first time speech had been transmitted from 

 America to Europe. Transatlantic telephony was first accomplished 

 in 1915, when the American Telephone and Telegraph Company 

 transmitted from the Navy station at Arlington, Va., to the Eiffel 

 Tower, Paris. In these earlier tests, however, speech was received 

 in Paris only at occasional moments when transmission conditions 

 were exceptionally favorable. The success of the present tests 

 indicates the large amount of development which has been carried 

 out since this first date. 



The recent talking tests were carried out as part of an investigation 

 of transatlantic radio telephony. This investigation is directed 

 at determining (1) the effectiveness of new methods and apparatus 

 which have been developed for telephonically modulating and trans- 

 mitting the large amounts of power necessary for transoceanic opera- 

 tion, (2) the efficacy of improved methods for the reception of this 

 transmission and t for so selecting it as to give an extremely sharp 

 differentiation between the range of frequencies transmitted and all 

 the frequencies outside of this range; and (3) determining the trans- 

 mission characteristics for transatlantic distances and the variation 

 of the characteristics with the time of day and the season of the year, 

 including the measurement of the amount of static interference. 



The tests are being continued, particularly as regards the study 

 of transmission efficiency. 



Single Side-Band Eliminated Carrier Method 



of Transmission 



The method of transmission used in these experiments is what we 



know as the single side-band eliminated carrier method 2 . With this 



2 For a more complete exposition of this method see U. S. patent No. 1449382 

 issued to John R. Carson to whom belongs the credit for having first suggested it. 

 Also see Carson patents Nos. 1,343,306 and 1,343,307. 



