Radio Telephone Service to Ships at Sea

The paper discusses the American end of the ship-to-shore radio telephone system and the connecting equipment on board the Leviathan. The most suitable wavelengths for this service are in the short-wave range, but the use of these wavelengths complicates the problem, since different wavelengths are required according to the distance of the ship from shore, the time of day, season of year, etc. The problem on shipboard is further complicated by the fact that the transmitting and receiving systems are necessarily near together and special precautions are necessary to take care of interference from the radio telephone transmitter and the radio telegraphic services. In addition to interference from these sources, there is a background of interference in the ship´s electrical equipment, all of which necessitates a much more powerful land station than is necessary on shipboard. In the present system, the shore transmitter has a power rating of 15 kw. and the ship transmitter of 500 watts. The shore transmitting station is located at Ocean Gate, N. J., and the receiving station at Forked River, N. J. At both of these locations, directive antennas are employed which cover the ship´s lanes. The stations are connected by wire to the Long Lines toll office in New York, and the over-all control of the circuit is carried out from this point. Both the ship and shore transmitters are crystal controlled. The ship´s receiver is highly selective and is of the double-detection type.