Hartley, Ralph V.L.

SUBJECT AREA: Broadcasting, Electronics and information technology, Telecommunications

[br]

b. 1889 USA

d. 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 Distinctions

Institution of Electrical and Electronics Enginners Medal of Honour 1946.

Bibliography

29 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 Technical

Journal (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 Reading

M.D.Fagen (ed.), 1975, A History of Engineering \& Science in the Bell System, Vol. 1: Bell Laboratories.

KF