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BELL SYSTEM TECHNICAL JOURNAL 



These results indicate that if full advantage is to be obtained from the 

 more reliable surface-wave component, the coastal station should be 

 immediately upon the seacoast or a salt-water bay. 



An important factor in connection with radio reception on ship- 

 board is that of electrical interference. The modern steamship re- 

 quires for its operation and its service a large amount of electrical 

 machinery. In addition to this, it is equipped with various radio 

 telegraphic services. The operation of all of this electrical equipment 

 produces interference in a receiver which is much in excess of that 

 normally encountered in a shore receiving station which can be so 

 located as to be reasonably free from electrical disturbances. Further- 

 more, there is on the ship another source of disturbance which is due to 



Fig. 3 — U. S. coastal station, circuit between New York and ship. 



charging and discharging of various parts of the rigging in the strong 

 electromagnetic fields of the various radio transmitters. These various 

 sources of disturbance were found in the earlier shipboard experiments 

 and the high noise levels are, in general, the predominant factor in 

 limiting the communication range. These factors made it desirable 

 to employ at the shore end as powerful a transmitter as was available 

 and to use whatever benefit could be obtained from antennas designed 

 to be roughly directive along the transatlantic ship lanes. A trans- 

 mitting set of the type used in transatlantic communication, but 

 adapted for the ship-to-shore wavelengths, was therefore employed. 

 Since the shore receiver can be located in a comparativ^ely quiet 

 situation and since use can also be made of roughly directive receiving 

 antennas, there is no advantage in transmitting as large an amount of 



