Ralph Hartley
Born(1888-11-30)November 30, 1888
DiedMay 1, 1970(1970-05-01) (aged 81)
Alma materUniversity of Utah
Oxford University
Known forHartley function
Hartley modulator
Hartley oscillator
Hartley transform
Shannon–Hartley theorem
AwardsIEEE Medal of Honor (1946)
Scientific career
FieldsElectrical engineering

Ralph Vinton Lyon Hartley (November 30, 1888 – May 1, 1970) was an American electronics researcher. He invented the Hartley oscillator and the Hartley transform, and contributed to the foundations of information theory.

His legacy includes the naming of the hartley, a unit of information equal to one decimal digit, after him.


Hartley was born in Sprucemont, Nevada, and attended the University of Utah, receiving an A.B. degree in 1909. He became a Rhodes Scholar at St Johns, Oxford University, in 1910 and received a B.A. degree in 1912 and a B.Sc. degree in 1913. He married Florence Vail of Brooklyn on March 21, 1916.[1] The Hartleys had no children.

He returned to the United States and was employed at the Research Laboratory of the Western Electric Company. In 1915 he was in charge of radio receiver development for the Bell System transatlantic radiotelephone tests. For this he developed the Hartley oscillator and also a neutralizing circuit to eliminate triode singing resulting from internal coupling. A patent for the oscillator was filed on June 1, 1915 and awarded on October 26, 1920.

During World War I Hartley established the principles that led to sound-type directional finders.

Following the war he returned to Western Electric. He later worked at Bell Laboratories. He performed research on repeaters and voice and carrier transmission and formulated the law "that the total amount of information that can be transmitted is proportional to frequency range transmitted and the time of the transmission." His 1928 paper is considered as "the single most important prerequisite" for Shannon's theory of information.[2] After about 10 years of illness he returned to Bell Labs in 1939 as a consultant.

In spite of his illness during most of the 1930s, Hartley had formed a theoretical and experimental research group at Bell Laboratories starting in 1929[3][4] to investigate nonlinear oscillations and what later became known as parametric amplifiers. This research was mostly parallel to the work being done at the same time in Soviet Russia by Leonid Mandelstam[5] and in Europe by Balthasar van der Pol.[6][7][8] A short review and extensive bibliography was published by Mumford in 1960.[9] The Bell Laboratories work was carried on under Hartley's guidance during the 1930s and 1940s by John Burton and Eugene Peterson (who themselves had begun investigations of nonlinear circuits as far back as 1917[10][11] when they had observed unusual characteristics while working with E.F.W. Alexanderson's magnetic modulators, an early form of magnetic amplifier). Peterson later got John Manley[12][13][14][15] and Harrison Rowe involved in this line of research during the 1940s which culminated in the now famous Manley–Rowe relations and several papers by the latter two authors[16][17][18] on the topic of parametric circuits in the mid 1950s.

During World War II he was particularly involved with servomechanism problems.

He retired from Bell Labs in 1950 and died on May 1, 1970.



Probably incomplete.

See also


  1. ^ Frank Aydelotte (1916). The American Oxonian. Association of American Rhodes Scholars. p. 84.
  2. ^ Frank, S. A. (February 2009). "Natural selection maximizes Fisher information". Journal of Evolutionary Biology. 22 (2): 231–244. arXiv:0901.3742. doi:10.1111/j.1420-9101.2008.01647.x. PMID 19032501. S2CID 7886157.
  3. ^ Hartley, R.V.L., "A Wave Mechanism of Quantum Phenomena"; Physical Review, Volume 33 Page 289, 1929 (abstract only)
  4. ^ Hartley, R.V.L., "Oscillations in Systems with Non-Linear Reactance", The Bell System Technical Journal, Volume 15, Number 3, July 1936, pg 424 - 440
  5. ^ Mandelstam L.I., Papalexi N., Andronov A., Chaikin S., Witt A., "Report on Recent Research on Nonlinear Oscillations", Technical Physics in the USSR, Leningrad, Volume 2, Numbers 2-3, 1935, pp 81 – 134, (NASA Translation Doc TTF-12,678; November 1969)
  6. ^ Van der Pol, B., "On relaxation-oscillations,' Philosophical Magazine, ser.7, vol. 2, pp. 987-992; November 1926
  7. ^ Van der Pol, B. and Van der Mark, J., "Frequency demultiplication", Nature, 120, 363-364, (1927)
  8. ^ Van der Pol, B., "Nonlinear theory of electric oscillations," Proceedings of the IRE, vol. 22, pp. 1051-1086; September 1934
  9. ^ Mumford W.W., "Some Notes on the History of Parametric Transducers", Proceedings of the IRE, Volume 48, Issue 5, pp848 - 853, (May 1960)
  10. ^ Peterson E., "Complex Magnetization"; Physical Review, Volume 27, Issue 3, March 1926 pg 318 - 328
  11. ^ Peterson E., "Atomic Physics and Circuit Theory"; Bell Laboratories Record, Volume 7, February 1929, pg 231-233
  12. ^ Peterson E., Manley J.M., Wrathall L.R.," Magnetic Generation of a Group of Harmonics", The Bell System Technical Journal, Volume 16, Number 4, October 1937 pp 437 – 455
  13. ^ Manley J.M., Peterson E., "Negative Resistance Effects in Saturable Reactor Circuits", AIEE Transactions, Volume 65, December 1946, pp 870 – 881
  14. ^ Manley J.M., "Some General Properties of Magnetic Amplifiers", Proceedings of the IRE, Volume 39, March 1951, pp 242 – 251
  15. ^ Manley, J. (August 1960). "Some Properties of Time Varying Networks". IRE Transactions on Circuit Theory. 7 (5): 69–78. doi:10.1109/TCT.1960.1086729. ISSN 0096-2007.
  16. ^ Manley J.M., Rowe H.E., "Some General Properties of Nonlinear Elements – Part I: General Energy Relations", Proceedings of the IRE, Volume 44, July 1956, pp 904 – 913
  17. ^ Rowe H.E., "Some General Properties of Nonlinear Elements – Part II: Small Signal Theory", Proceedings of the IRE, Volume 46, May 1958, pp 850 – 860
  18. ^ Manley J.M., Rowe H.E., "General Energy Relations in Nonlinear Reactances", Proceedings of the IRE, Volume 47, December 1959, pp 2115–2116


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