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1 Hartley, Ralph V.L.
[br]b. 1889 USAd. 1 May 1970 Summit, New Jersey, USA[br]American engineer who made contributions to radio communications.[br]Hartley obtained his BA in 1909 from the University of Utah, then gained a Rhodes Scholarship to Oxford University, England. After obtaining a further BA and a BSc in 1912 and 1913, respectively, he returned to the USA and took a job with the Western Electric Laboratories of the Bell Telephone Company, where he was in charge of radio-receiver development. In 1915 he invented the Hartley oscillator, analogous to that invented by Colpitts. Subsequently he worked on carrier telephony at Western Electric and then at Bell Laboratories. There he concen-trated on information theory, building on the pioneering work of Nyquist, in 1926 publishing his law that related information capacity, frequency bandwidth and time. Forced to give up work in 1929 due to ill health, he returned to Bell in 1939 as a consultant on transmission problems. During the Second World War he worked on various projects, including the use of servo-mechanisms for radar and fire control, and finally retired in 1950.[br]Principal Honours and DistinctionsInstitution of Electrical and Electronics Enginners Medal of Honour 1946.Bibliography29 May 1918, US patent no. 1,592,934 (plate modulator).29 September 1919, US patent no. 1,419,562 (balanced modulator or detector). 1922, with T.C.Fry, "Binaural location of complex sounds", Bell Systems TechnicalJournal (November).1923, "Relation of carrier and sidebands in radio transmission", Proceedings of the Institute of Radio Engineers 11:34.1924, "The transmission unit", Electrical Communications 3:34.1926, "Transmission limits of telephone lines", Bell Laboratories Record 1:225. 1928, "Transmission of information", Bell Systems Technical Journal (July).1928, "“TU” becomes Decibel", Bell Laboratories Record 7:137.1936, "Oscillations in systems with non-linear reactance", Bell System Technology Journal 15: 424.Further ReadingM.D.Fagen (ed.), 1975, A History of Engineering \& Science in the Bell System, Vol. 1: Bell Laboratories.KF -
2 Broadcasting
See also: INDEX BY SUBJECT AREA[br] -
3 Colpitts, Edwin Henry
[br]b. 9 January 1872 Pointe de Bute, Canadad. 6 March 1949 Orange, New Jersey, USA[br]Canadian physicist and electrical engineer responsible for important developments in electronic-circuit technology.[br]Colpitts obtained Bachelor's degrees at Mount Allison University, Sackville, New Brunswick, and Harvard in 1894 and 1896, respectively, followed by a Master's degree at Harvard in 1897. After two years as assistant to the professor of physics there, he joined the American Bell Telephone Company. When the Bell Company was reorganized in 1907, he moved to the Western Electric branch of the company in New York as Head of the Physical Laboratories. In 1911 he became a director of the Research Laboratories, and in 1917 he became Assistant Chief Engineer of the company. During this time he invented both the push-pull amplifier and the Colpitts oscillator, both major developments in communications. In 1917, during the First World War, he spent some time in France helping to set up the US Signal Corps Research Laboratories. Afterwards he continued to do much, both technically and as a manager, to place telephone communications on a firm scientific basis, retiring as Vice-President of the Bell Telephone Laboratories in 1937. With the outbreak of the Second World War in 1941 he was recalled from retirement and appointed Director of the Engineering Foundation to work on submarine warfare techniques, particularly echo-ranging.[br]Principal Honours and DistinctionsOrder of the Rising Sun, Japan, 1938. US Medal of Merit 1948.Bibliography1919, with E.B.Craft, "Radio telephony", Proceedings of the American Institution of Electrical Engineers 38:337.1921, with O.B.Blackwell, "Carrier current telephony and telegraphy", American Institute of Electrical Engineers Transactions 40:205.11 September 1915, US reissue patent no. 15,538 (control device for radio signalling).28 August 1922, US patent no. 1,479,638 (multiple signal reception).Further ReadingM.D.Fagen, 1975, A History of Engineering \& Science in the Bell System, Vol. 1, Bell Laboratories.See also: Hartley, Ralph V.L.KF -
4 Electronics and information technology
See also: INDEX BY SUBJECT AREA[br]Byron, Ada AugustaNapier, JohnRiche, Gaspard-Clair-François-MarieSchickhard, WilhelmBiographical history of technology > Electronics and information technology
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5 Telecommunications
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