Harry Nyquist
Encyclopedia
Harry Nyquist was an important contributor to information theory
.
, Sweden
. He was the son of Lars Jonsson Nyqvist (b. 1847) and Katrina Eriksdotter (b. 1857). His parents had seven children: Elin Teresia, Astrid, Selma, Harry Theodor, Aemelie, Olga Maria, and Axel. He emigrated to the USA
in 1907.
in 1912 and received the 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.
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."
Nyquist lived in Pharr, Texas
after his retirement, and died in Harlingen, Texas
on April 4, 1976.
"), the stability of feedback
amplifier
s, telegraphy, facsimile
, 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 classical 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
. 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). This rule is essentially a dual
of what is now known as the Nyquist–Shannon sampling theorem
.
Information theory
Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
.
Personal life
Nyquist was born in the Stora Kil parish of Nilsby, VärmlandVärmland
' is a historical province or landskap in the west of middle Sweden. It borders Västergötland, Dalsland, Dalarna, Västmanland and Närke. It is also bounded by Norway in the west. Latin name versions are Vermelandia and Wermelandia. Although the province's land originally was Götaland, the...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. He was the son of Lars Jonsson Nyqvist (b. 1847) and Katrina Eriksdotter (b. 1857). His parents had seven children: Elin Teresia, Astrid, Selma, Harry Theodor, Aemelie, Olga Maria, and Axel. He emigrated to the USA
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in 1907.
Education
He entered the University of North DakotaUniversity of North Dakota
The University of North Dakota is a public university in Grand Forks, North Dakota, USA. Established by the Dakota Territorial Assembly in 1883, six years before the establishment of the state of North Dakota, UND is the oldest and largest university in the state and enrolls over 14,000 students. ...
in 1912 and received the B.S. and M.S. degrees in electrical engineering in 1914 and 1915, respectively. He received a Ph.D.
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
in physics at Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
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 in that year, until his retirement in 1954.Nyquist received the IRE Medal of Honor
IEEE Medal of Honor
The IEEE Medal of Honor is the highest recognition of the Institute of Electrical and Electronics Engineers . It has been awarded since 1917, when its first recipient was Major Edwin H. Armstrong. It is given for an exceptional contribution or an extraordinary career in the IEEE fields of...
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
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...
"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
National Academy of Engineering
The National Academy of Engineering is a government-created non-profit institution in the United States, that was founded in 1964 under the same congressional act that led to the founding of the National Academy of Sciences...
's fourth Founder's Medal "in recognition of his many fundamental contributions to engineering."
Nyquist lived in Pharr, Texas
Pharr, Texas
Pharr is a city in Hidalgo County, Texas, United States. As of the 2010 census, the city population was 70,400. Pharr is connected by bridge to the Mexican city of Reynosa, Tamaulipas...
after his retirement, and died in Harlingen, Texas
Harlingen, Texas
Harlingen is a city in Cameron County in the heart of the Rio Grande Valley of south Texas, United States, about from the coast of the Gulf of Mexico. The city covers more than , and is the second largest city in Cameron County and the sixth largest in the Rio Grande Valley...
on April 4, 1976.
Technical contributions
As an engineer at Bell Laboratories, Nyquist did important work on thermal noise ("Johnson–Nyquist noiseJohnson–Nyquist noise
Johnson–Nyquist noise is the electronic noise generated by the thermal agitation of the charge carriers inside an electrical conductor at equilibrium, which happens regardless of any applied voltage...
"), the stability of feedback
Feedback
Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...
amplifier
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
s, telegraphy, facsimile
Fax
Fax , sometimes called telecopying, is the telephonic transmission of scanned printed material , normally to a telephone number connected to a printer or other output device...
, television, and other important communications problems. With Herbert E. Ives
Herbert E. Ives
Herbert Eugene Ives was a scientist and engineer who headed the development of facsimile and television systems at AT&T in the first half of the twentieth century. He was also a critic of the special theory of relativity, and attempted to disprove the theory by means of logical arguments and...
, he helped to develop AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
's first facsimile machines that were made public in 1924. In 1932, he published a classical paper on stability of feedback amplifiers. The Nyquist stability criterion
Nyquist stability criterion
When designing a feedback control system, it is generally necessary to determine whether the closed-loop system will be stable. An example of a destabilizing feedback control system would be a car steering system that overcompensates -- if the car drifts in one direction, the control system...
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
Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
. 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). This rule is essentially a dual
Duality (mathematics)
In mathematics, a duality, generally speaking, translates concepts, theorems or mathematical structures into other concepts, theorems or structures, in a one-to-one fashion, often by means of an involution operation: if the dual of A is B, then the dual of B is A. As involutions sometimes have...
of what is now known as the Nyquist–Shannon sampling theorem
Nyquist–Shannon sampling theorem
The Nyquist–Shannon sampling theorem, after Harry Nyquist and Claude Shannon, is a fundamental result in the field of information theory, in particular telecommunications and signal processing. Sampling is the process of converting a signal into a numeric sequence...
.
See also
- Nyquist filterNyquist filterA Nyquist filter is an electronic filter used in TV receivers to equalize the video characteristics. The filter is named after the Swedish–US engineer Harry Nyquist .- VSB :...
- Nyquist plotNyquist plotA Nyquist plot is a parametric plot of a transfer function used in automatic control and signal processing. The most common use of Nyquist plots is for assessing the stability of a system with feedback. In Cartesian coordinates, the real part of the transfer function is plotted on the X axis. The...
- Nyquist rateNyquist rateIn signal processing, the Nyquist rate, named after Harry Nyquist, is two times the bandwidth of a bandlimited signal or a bandlimited channel...
- Nyquist frequencyNyquist frequencyThe Nyquist frequency, named after the Swedish-American engineer Harry Nyquist or the Nyquist–Shannon sampling theorem, is half the sampling frequency of a discrete signal processing system...
- Nyquist ISI criterionNyquist ISI criterionIn communications, the Nyquist ISI criterion describes the conditions which, when satisfied by a communication channel, result in no intersymbol interference or ISI...
External links
- IEEE Global History Network page about Nyquist
- Nyquist criterion page with photo of Nyquist with John R. Pierce and Rudy Kompfner
- K.J.Astrom: Nyquist and his seminal papers, 2005 presentation
- Nyquist biography, p. 2