RADIO TELEPHONE SERVICE TO SHIPS AT SEA 



409 



justify the initiation of the new service at that time. Furthermore, 

 the waves in the range of 300-500 meters, which had been used in these 

 early trials, were soon thereafter assigned for broadcasting. 



In the last few years the whole outlook has changed considerably. 

 The development of short-wave radio systems has greatly increased the 

 message carrying capacity of the radio spectrum and has made it feasi- 

 ble to maintain communication over a greater range of distances than 

 was previously practicable for ships. Transoceanic radio telephone 

 services have been inaugurated, and with the large increase in steam- 

 ship travel there has arisen a renewed interest in the extension of 

 telephone service to ships at sea. 



When it became evident that short-wave transmission might be 



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Fig. 1 — Received Fields, New York-Bermuda Run 1925. 



desirable for ship-to-shore telephone service, there was undertaken a 

 program involving the measurement of the strength of the electric 

 fields received aboard ship from a shore transmitter. This work was 

 part of a general program intended to obtain fundamental data upon 

 short-wave transmission, for purposes of point-to-point, as well as for 

 ship-to-shore telephone services. The tests were first made in 1925 on 

 vessels running between New York and Bermuda. Further measure- 

 ments were made on other ships in subsequent years. 



Fig. 1 is an example of the result of these earlier tests. Transmission 

 was from Deal Beach on 4.5 megacycles (66 meters). The curve shows 

 the relatively weak field which was received as the vessel left dock, due 

 to the considerable stretch of land which intervened in the transmission 



