180 BELL SYSTEM TECHNICAL JOURNAL 



Corporation of America. The engineers of these companies built a 

 ship set similar to that developed in the work described above, but 

 of a more commercial design, and installed in on the S. S. America 

 in January. 1922. 4 During the succeeding few months, tests were 

 made between the S. S. America and the shore, and on a number of 

 these trips connections were put up to various interested parties 

 around New York when the ship was within about 300 miles (480 km.) 

 of the Deal Beach station. Of course, the America was carried out 

 much farther than this at night, but the circuits were not sufficiently 

 reliable to be used in connection with the land lines as will be appre- 

 ciated from the field strength measurements given above. 



A photograph of a portion of the installation on the S. S. America 

 is reproduced in Fig. 9 above. The talking tests made with the 

 America were the occasion of much interest on the part of the listeners- 

 in, and several of the demonstrations which were given the subject of 

 newspaper accounts and need not be described. The more technical 

 phases of the tests with the S. S. America are (a) the field strength 

 measurements, and (b) the simultaneous telegraph tests discussed 

 below. 



Simultaneous Telephone and Telegraph Operation Between 



Ship and Shore 



During the experiments with the Steamships Gloucester and Ontario, 

 the radio telephone transmissions were carried on alternately with the 

 conduct of the regular radio telegraph service of the vessels. Simul- 

 taneous operation was impossible because the vessels were equipped 

 with spark transmitters. While this arrangement of having to 

 switch between either telephone and telegraph operation is permissible 

 tor small vessels where the communication load is light, it is, of course, 

 not satisfactory for large trans-oceanic vessels where the message 

 business may be such as to require practically continuous operation 

 on the part of both services. 



Recognizing, therefore, that one of the problems attending the 

 successful application of radio telephony to large vessels is that of 

 simultaneous telephone and telegraph operation, tests of such trans- 

 mission were conducted in co-operation with the Radio Corporation 

 of America from the S. S. America. These were made during Febru- 

 ary and March of 1922. On the land ends, the two radio circuits 

 terminated at different stations, the telegraph at the Bush Ter- 



4 See article "Duplex Radio Telephone Transmitter," by Baker and Byrnes. 

 General Electrical Review, August, 1922. 



