Marine Radio Telephone Service for Boston Harbor * 



By F. A. GIFFORD and R. B. HEADER 



THERE has been a constantly increasing interest in an inexpensive 

 service for small harbor and coastal craft such as tugboats, 

 private yachts, coastal passenger ships, merchant craft and fishing 

 vessels. This interest became particularly evident in New England 

 in 1931 and since equipment suitable for the purpose had recently 

 been developed by Bell Telephone Laboratories, the New England 

 Telephone and Telegraph Company undertook the establishment of a 

 marine radio telephone service. 



A survey consisting of a comprehensive series of field strength 

 measurements on shipboard and at various points along the coasts of 

 Massachusetts and Cape Cod Bays resulted in selecting Green Harbor 

 as the location for a shore station. Green Harbor is in the town of 

 Marshfield, Massachusetts, about 28 miles southeast of Boston. 



A commercial survey indicated that initially the service would be 

 of interest chiefly to the Boston fishing industry. Consequently, boat 

 radio telephone equipment was installed on the trawler "Flow" of the 

 Bay State Fishing Company and the service was opened in June, 1932, 

 on a demonstration basis. As tests with this vessel progressed, it 

 became evident that the radio telephone service would fulfill the com- 

 munications requirements of the fishing industry. It also became 

 apparent that a complete service of this type should include some 

 means for determining the vessel's position at any time by means of 

 radio. Therefore, the development of such equipment was initiated ' 

 by Bell Telephone Laboratories as an adjunct to the radio telephone 

 service, and the outcome of tests of an experimental model indicates 

 that the problem of providing suitable radio compass equipment in the 

 price range satisfactory to the fishing fleet owners has been satis- 

 factorily solved. 



The radio transmitter is a 400-watt crystal-controlled type similar 

 to those designed for use at aviation ground stations and adjusted to 

 operate at a frequency of 2506 kilocycles. This frequency is main- 

 tained within limits of better than 0.025 per cent. 



In order to combine the two unidirectional radio channels into a two- 

 way circuit suitable for connection to the ordinary wire circuits in the 



* Digest of a paper to be published in full in Communication and Broadcast 

 Engineering, October, 1935. 



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