Radio Telephone Service to Ships at Sea

Radio Telephone Service to Ships at Sea * B y W I L L I A M W I L S O N and L L O Y D E S P E N S C H I E D 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 a n d special precautions are necessary to take care of interference from the radio telephone transmitter a n d the radio telegraphic services. In addition to interference from these sources, there is a background of interference in the ships' electrical equipment, all of which necessitates a much more powerful land station t h a n is necessary on shipboard. In the present system, the shore transmitter has a power rating of 15 kw. a n d 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 ships' lanes. The stations are connected by wire to the Long Lines toll office in New York, a n d the over-all control of the circuit is carried out from this point. Both the ship a n d shore transmitters are crystal controlled.