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1 Nyquist, Harry
[br]b. 7 February 1889 Nilsby, Swedend. 4 April 1976 Texas, USA[br]Swedish-American engineer who established the formula for thermal noise in electrical circuits and the stability criterion for feedback amplifiers.[br]Nyquist (original family name Nykvist) emigrated from Sweden to the USA when he was 18 years old and settled in Minnesota. After teaching for a time, he studied electrical engineering at the University of North Dakota, gaining his first and Master's degrees in 1915 and 1916, and his PhD from Yale in 1917. He then joined the American Telegraph \& Telephone Company, moving to its Bell Laboratories in 1934 and remaining there until his retirement in 1954. A prolific inventor, he made many contributions to communication engineering, including the invention of vestigial-side band transmission. In the late 1920s he analysed the behaviour of analogue and digital signals in communication circuits, and in 1928 he showed that the thermal noise per unit bandwidth is given by 4 kT, where k is Boltzmann's constant and T the absolute temperature. However, he is best known for the Nyquist Criterion, which defines the conditions necessary for the stable, oscillation-free operation of amplifiers with a closed feedback loop. The problem of how to realize these conditions was investigated by his colleague Hendrik Bode.[br]Principal Honours and DistinctionsFranklin Institute Medal 1960. Institute of Electrical and Electronics Engineers Medal of Honour 1960; Mervin J.Kelly Award 1961.Bibliography1924, "Certain factors affecting telegraph speed", Bell System Technical Journal 3:324. 1928, "Certain topics in telegraph transmission theory", Transactions of the AmericanInstitute of Electrical Engineers 47:617.1928, "Thermal agitation of electric charge in conductors", Physical Review 32:110. 1932, "Regeneration theory", Bell System Technical Journal 11:126.1940, with K.Pfleger, "Effect of the quadrature component in single-sideband transmission", Bell System Technical Journal 19:63.Further ReadingBell Telephone Laboratories, 1975, Mission Communications.See also: Shannon, Claude ElwoodKF -
2 Bode, Hendrik Wade
[br]b. 24 December 1905 Madison, Wisconsin, USAd. 21 June 1982 Cambridge, Massachusetts, USA[br]American engineer who developed an extensive theoretical understanding of the behaviour of electronic circuits.[br]Bode received his bachelor's and master's degrees from Ohio State University in 1924 and 1926, respectively, and his PhD from Columbia University, New York, in 1935. In 1926 he joined the Bell Telephone Laboratories, where he made many theoretical contributions to the understanding of the behaviour of electronic circuits and, in particular, in conjunction with Harry Nyquist, of the conditions under which amplifier circuits become unstable.During the Second World War he worked on the design of gun control systems and afterwards was a member of a team that worked with Douglas Aircraft to develop the Nike anti-aircraft missile. A member of the Bell Laboratories Mathematical Research Group from 1929, he became its Director in 1952, and then Director of Physical Sciences. Finally he became Vice-President of the Laboratories, with responsibility for systems engineering, and a director of Bellcomm, a Bell company involved in the Moon-landing programme. When he retired from Bell in 1967, he became Professor of Systems Engineering at Harvard University.[br]Principal Honours and DistinctionsPresidential Certificate of Merit 1946. Institute of Electrical and Electronics Engineers Edison Medal 1969.Bibliography1940, "Relation between attenuation and phase in feedback amplifier design", Bell System Technical Journal 19:421.1945, Network Analysis and Feedback Amplifier Design, New York: Van Nostrand.1950, with C.E.Shannon, "A simplified derivation of linear least squares smoothing and prediction theory", Proceedings of the Institute of Radio Engineers 38:417.1961, "Feedback. The history of an idea", Proceedings of the Symposium on Active Networks and Feedback Systems, Brooklyn Polytechnic.1971, Synergy: Technical Integration and Technical Innovation in the Bell System Bell Laboratories, Bell Telephone Laboratories (provides background on his activities at Bell).Further ReadingP.C.Mahon, 1975, Mission Communications, Bell Telephone Laboratories. See also Black, Harold Stephen; Shannon, Claude Elwood.KF -
3 Shannon, Claude Elwood
[br]b. 30 April 1916 Gaylord, Michigan, USA[br]American mathematician, creator of information theory.[br]As a child, Shannon tinkered with radio kits and enjoyed solving puzzles, particularly crypto-graphic ones. He graduated from the University of Michigan in 1936 with a Bachelor of Science in mathematics and electrical engineering, and earned his Master's degree from the Massachusetts Institute of Technology (MIT) in 1937. His thesis on applying Boolean algebra to switching circuits has since been acclaimed as possibly the most significant this century. Shannon earned his PhD in mathematics from MIT in 1940 with a dissertation on the mathematics of genetic transmission.Shannon spent a year at the Institute for Advanced Study in Princeton, then in 1941 joined Bell Telephone Laboratories, where he began studying the relative efficiency of alternative transmission systems. Work on digital encryption systems during the Second World War led him to think that just as ciphers hide information from the enemy, "encoding" information could also protect it from noise. About 1948, he decided that the amount of information was best expressed quantitatively in a two-value number system, using only the digits 0 and 1. John Tukey, a Princeton colleague, named these units "binary digits" (or, for short, "bits"). Almost all digital computers and communications systems use such on-off, or two-state logic as their basis of operation.Also in the 1940s, building on the work of H. Nyquist and R.V.L. Hartley, Shannon proved that there was an upper limit to the amount of information that could be transmitted through a communications channel in a unit of time, which could be approached but never reached because real transmissions are subject to interference (noise). This was the beginning of information theory, which has been used by others in attempts to quantify many sciences and technologies, as well as subjects in the humanities, but with mixed results. Before 1970, when integrated circuits were developed, Shannon's theory was not the preferred circuit-and-transmission design tool it has since become.Shannon was also a pioneer in the field of artificial intelligence, claiming that computing machines could be used to manipulate symbols as well as do calculations. His 1953 paper on computers and automata proposed that digital computers were capable of tasks then thought exclusively the province of living organisms. In 1956 he left Bell Laboratories to join the MIT faculty as Professor of Communications Science.On the lighter side, Shannon has built many devices that play games, and in particular has made a scientific study of juggling.[br]Principal Honours and DistinctionsNational Medal of Science. Institute of Electrical and Electronics Engineers Medal of Honor, Kyoto Prize.BibliographyHis seminal paper (on what has subsequently become known as information theory) was entitled "The mathematical theory of communications", first published in Bell System Technical Journal in 1948; it is also available in a monograph (written with Warren Weaver) published by the University of Illinois Press in 1949, and in Key Papers in the Development of Information Theory, ed. David Slepian, IEEE Press, 1974, 1988. For readers who want all of Shannon's works, see N.J.A.Sloane and A.D.Wyner, 1992, TheCollected Papers of Claude E.Shannon.HO -
4 BSTJ
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5 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 -
6 Paul, Robert William
[br]b. 3 October 1869 Highbury, London, Englandd. 28 March 1943 London, England[br]English scientific instrument maker, inventor of the Unipivot electrical measuring instrument, and pioneer of cinematography.[br]Paul was educated at the City of London School and Finsbury Technical College. He worked first for a short time in the Bell Telephone Works in Antwerp, Belgium, and then in the electrical instrument shop of Elliott Brothers in the Strand until 1891, when he opened an instrument-making business at 44 Hatton Garden, London. He specialized in the design and manufacture of electrical instruments, including the Ayrton Mather galvanometer. In 1902, with a purpose-built factory, he began large batch production of his instruments. He also opened a factory in New York, where uncalibrated instruments from England were calibrated for American customers. In 1903 Paul introduced the Unipivot galvanometer, in which the coil was supported at the centre of gravity of the moving system on a single pivot. The pivotal friction was less than in a conventional instrument and could be used without accurate levelling, the sensitivity being far beyond that of any pivoted galvanometer then in existence.In 1894 Paul was asked by two entrepreneurs to make copies of Edison's kinetoscope, the pioneering peep-show moving-picture viewer, which had just arrived in London. Discovering that Edison had omitted to patent the machine in England, and observing that there was considerable demand for the machine from show-people, he began production, making six before the end of the year. Altogether, he made about sixty-six units, some of which were exported. Although Edison's machine was not patented, his films were certainly copyrighted, so Paul now needed a cinematographic camera to make new subjects for his customers. Early in 1895 he came into contact with Birt Acres, who was also working on the design of a movie camera. Acres's design was somewhat impractical, but Paul constructed a working model with which Acres filmed the Oxford and Cambridge Boat Race on 30 March, and the Derby at Epsom on 29 May. Paul was unhappy with the inefficient design, and developed a new intermittent mechanism based on the principle of the Maltese cross. Despite having signed a ten-year agreement with Paul, Acres split with him on 12 July 1895, after having unilaterally patented their original camera design on 27 May. By the early weeks of 1896, Paul had developed a projector mechanism that also used the Maltese cross and which he demonstrated at the Finsbury Technical College on 20 February 1896. His Theatrograph was intended for sale, and was shown in a number of venues in London during March, notably at the Alhambra Theatre in Leicester Square. There the renamed Animatographe was used to show, among other subjects, the Derby of 1896, which was won by the Prince of Wales's horse "Persimmon" and the film of which was shown the next day to enthusiastic crowds. The production of films turned out to be quite profitable: in the first year of the business, from March 1896, Paul made a net profit of £12,838 on a capital outlay of about £1,000. By the end of the year there were at least five shows running in London that were using Paul's projectors and screening films made by him or his staff.Paul played a major part in establishing the film business in England through his readiness to sell apparatus at a time when most of his rivals reserved their equipment for sole exploitation. He went on to become a leading producer of films, specializing in trick effects, many of which he pioneered. He was affectionately known in the trade as "Daddy Paul", truly considered to be the "father" of the British film industry. He continued to appreciate fully the possibilities of cinematography for scientific work, and in collaboration with Professor Silvanus P.Thompson films were made to illustrate various phenomena to students.Paul ended his involvement with film making in 1910 to concentrate on his instrument business; on his retirement in 1920, this was amalgamated with the Cambridge Instrument Company. In his will he left shares valued at over £100,000 to form the R.W.Paul Instrument Fund, to be administered by the Institution of Electrical Engineers, of which he had been a member since 1887. The fund was to provide instruments of an unusual nature to assist physical research.[br]Principal Honours and DistinctionsFellow of the Physical Society 1920. Institution of Electrical Engineers Duddell Medal 1938.Bibliography17 March 1903, British patent no. 6,113 (the Unipivot instrument).1931, "Some electrical instruments at the Faraday Centenary Exhibition 1931", Journal of Scientific Instruments 8:337–48.Further ReadingObituary, 1943, Journal of the Institution of Electrical Engineers 90(1):540–1. P.Dunsheath, 1962, A History of Electrical Engineering, London: Faber \& Faber, pp.308–9 (for a brief account of the Unipivot instrument).John Barnes, 1976, The Beginnings of Cinema in Britain, London. Brian Coe, 1981, The History of Movie Photography, London.BC / GW
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