Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

504 FREQUENCY MODULATION, Volume IFREQUENCY-MODULATION MOBILE RADIO-TELEPHONE SERVICES*!ByH. B. MartinAssistant Chief Engineer, Radiomarine Corporation of America,New York, N. Y.SummaryThe proposed use of frequencies in the Very High Frequency rangesof 30-/ f4 and 152-162 megacycles for Common-carrier General Mobile RadiotelephoneCommunication is discussed with reference to propagational andequipment advantages. Consideration is limited to the radio link forvehicular and marine mobile service. Frequency modulation and its advantagesfor mobile communication are discussed briefly. The use ofseparate transmitting and receiving frequencies is the basis for all recommendationsand allocation plans which are traced from their origin by theRadio Technical Planning Board to the most recent Industry suggestionsto the Federal Communications Commission. Geographical considerationsfor service areas of fixed stations are based on Radio Manufacturers Associationrecommendations for transmitter powers, antenna heights, desiredand undesired signal levels, etc. The Urban and Highway proposed services,including Marine, are compared on an operational and equipment basis andthe most important mobile unit performance requirements are given. Referencesfrom Radio Technical Planning Board (RTPB), Radio ManufacturersAssociation (RMA), Federal Communications Commission (FCC) andtechnical publications are provided.(12 pages; i tables)* Decimal Classification : R540.t RCA REVIEW, June, 1946.A FREQUENCY-MODULATED MAGNETRON FORSUPER-HIGH FREQUENCIES*!ByG. R. Kilgore, Carl I. Shulman, and J. KurshanResearch Department, RCA Laboratories Division,Princeton, N. J.SummaryThis paper is based on a wartime requirement for a 25-watt, 4000-megacyclecontinuous-wave oscillator capable of electronic frequency modulationwith a deviation of at least 2.5 megacycles. A satisfactory solution wasfound in the addition of frequency control to a continuous-wave magnetronby the introduction of electron beams into the magnetron cavities in amanner described by Smith and Shulman. This method is referred to as"spiral-beam" control.A brief account is given of the method of designing a continuous-wavemagnetron for the specified power and frequency. The problem of adding