Harry Nyquist (, ; February 7, 1889 – April 4, 1976) was a Swedish-American physicist and electronic engineer who made important contributions to

communication theory Communication theory is a proposed description of communication phenomena, the relationships among them, a storyline describing these relationships, and an argument for these three elements. Communication theory provides a way of talking about a ...

Personal life

Nyquist was born in the village Nilsby of the parish Stora Kil, Värmland,

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

. He was the son of Lars Jonsson Nyqvist (b. 1847) and Katrina Eriksdotter (b. 1857). His parents had eight children: Elin Teresia, Astrid, Selma, Harry Theodor, Amelie, Olga Maria, Axel Martin and Herta Alfrida. He emigrated to the USA in 1907.

Education

He entered the University of North Dakota in 1912 and received B.S. and M.S. degrees in electrical engineering in 1914 and 1915, respectively. He received a Ph.D. in physics at Yale University in 1917.

Career

He worked at AT&T's Department of Development and Research from 1917 to 1934, and continued when it became Bell Telephone Laboratories that year, until his retirement in 1954. Nyquist received the IRE Medal of Honor in 1960 for "fundamental contributions to a quantitative understanding of thermal noise, data transmission and negative feedback." In October 1960 he was awarded the Stuart Ballantine Medal of the Franklin Institute "for his theoretical analyses and practical inventions in the field of communications systems during the past forty years including, particularly, his original work in the theories of telegraph transmission, thermal noise in electric conductors, and in the history of feedback systems." In 1969 he was awarded the National Academy of Engineering's fourth Founder's Medal "in recognition of his many fundamental contributions to engineering." In 1975 Nyquist received together with Hendrik Bode the Rufus Oldenburger Medal from the

American Society of Mechanical Engineers The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing ...

. As reported in The Idea Factory, the Bell Labs patent lawyers wanted to know why some people were so much more productive (in terms of patents) than others. After crunching a lot of data, they found that the only thing the productive employees had in common (other than having made it through the Bell Labs hiring process) was that “… Workers with the most patents often shared lunch or breakfast with a Bell Labs electrical engineer named Harry Nyquist. It wasn’t the case that Nyquist gave them specific ideas. Rather, as one scientist recalled, ‘he drew people out, got them thinking.” (Pg. 135) Nyquist lived in Pharr, Texas after his retirement, and died in

Harlingen, Texas Harlingen ( ) is a city in Cameron County in the central region of the Rio Grande Valley of the southern part of the U.S. state of Texas, about from the coast of the Gulf of Mexico. The city covers more than and is the second-largest city in ...

on April 4, 1976.

Technical contributions

As an engineer at Bell Laboratories, Nyquist did important work on thermal noise (" Johnson–Nyquist noise"), the stability of

feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled ...

amplifiers, telegraphy,

facsimile A facsimile (from Latin ''fac simile'', "to make alike") is a copy or reproduction of an old book, manuscript, map, Old master print, art print, or other item of historical value that is as true to the original source as possible. It differs from ...

, television, and other important communications problems. With Herbert E. Ives, he helped to develop AT&T's first facsimile machines that were made public in 1924. In 1932, he published a classic paper on stability of feedback amplifiers. The Nyquist stability criterion can now be found in all textbooks on feedback control theory. His early theoretical work on determining the bandwidth requirements for transmitting information laid the foundations for later advances by Claude Shannon, which led to the development of

information theory Information theory is the scientific study of the quantification (science), quantification, computer data storage, storage, and telecommunication, communication of information. The field was originally established by the works of Harry Nyquist a ...

. In particular, Nyquist determined that the number of independent pulses that could be put through a telegraph channel per unit time is limited to twice the bandwidth of the channel, and published his results in the papers ''Certain factors affecting telegraph speed'' (1924) and ''Certain topics in Telegraph Transmission Theory'' (1928).Reprint as classic paper in: ''Proc. IEEE, Vol. 90, No. 2, Feb 2002''
This rule is essentially a

dual Dual or Duals may refer to: Paired/two things * Dual (mathematics), a notion of paired concepts that mirror one another ** Dual (category theory), a formalization of mathematical duality *** see more cases in :Duality theories * Dual (grammatical ...

of what is now known as the Nyquist–Shannon sampling theorem.

Terms named for Harry Nyquist

* Nyquist rate: sampling rate twice the bandwidth of the signal's waveform being sampled; sampling faster than this rate assures that the waveform can be reconstructed accurately. * Nyquist frequency: half the sample rate of a system; signal frequencies below this value are unambiguously represented. * Nyquist filter * Nyquist plot *

Nyquist ISI criterion In communications, the Nyquist ISI criterion describes the conditions which, when satisfied by a communication channel (including responses of transmit and receive filters), result in no intersymbol interference or ISI. It provides a method for con ...

* Nyquist (programming language) * Nyquist stability criterion

References

External links

*
IEEE Global History Network page about Nyquist

with photo of Nyquist with John R. Pierce and

Rudy Kompfner Rudolf Kompfner (May 16, 1909 – December 3, 1977) was an Austrian-born inventor, physicist and architect, best known as the inventor of the traveling-wave tube (TWT). Life Kompfner was born in Vienna to Jewish parents. He was original ...

K.J.Astrom: Nyquist and his seminal papers, 2005 presentation

Nyquist biography, p. 2
{{DEFAULTSORT:Nyquist, Harry 1889 births 1976 deaths People from Kil Municipality American electronics engineers AT&T people Control theorists IEEE Medal of Honor recipients American information theorists Information theory Scientists at Bell Labs University of North Dakota alumni Yale University alumni Swedish emigrants to the United States People from Pharr, Texas Mathematicians from Texas 20th-century American engineers Fellows of the American Physical Society