Prof. Dr. Thorsten Jungmann (last updated 2026-10-03)
Harry Nyquist (1889–1976) was a Swedish-American physicist and electronic engineer who made important contributions to communication theory and feedback control systems. He was born in Nilsby in Värmland, Sweden, and emigrated to the United States in 1907. He received B.S. and M.S. degrees in electrical engineering from the University of North Dakota in 1914 and 1915 and a Ph.D. in physics from Yale University in 1917. He then joined AT&T and moved to the Bell Telephone Laboratories in 1934. During his time in the Bell system he received 138 patents.
Nyquist’s work addressed practical problems of telegraphy and long-distance telephony, in particular how much information can be carried through a limited frequency band. In 1924 he showed that the speed at which information can be transmitted grows with the logarithm of the number of signal values (). In 1928 he established that an ideal channel of bandwidth can transmit up to independent signal elements per second. Shannon cited both papers, together with the work of Hartley, as important foundations for a general theory of communication.
Two terms in digital signal processing are named after Nyquist. The Nyquist rate is the sampling rate of twice the bandwidth of the signal being sampled; a signal sampled at a higher rate is free of the distortion known as aliasing. The Nyquist frequency (German: Nyquist-Frequenz) is half the sample rate of a system; signal frequencies below this value are unambiguously represented. The Nyquist–Shannon sampling theorem (German: Nyquist-Shannon-Abtasttheorem) also carries his name, although his papers of 1924 and 1928, which are often cited as its source, do not state the theorem explicitly; Kotelnikov discovered it independently in 1933. In his 1932 paper ‘Regeneration Theory’ Nyquist also gave the stability test for feedback amplifiers that is known as the Nyquist stability criterion. In 1975 he shared the Rufus Oldenburger Medal with Bode.
Reference and further reading:
https://en.wikipedia.org/wiki/Harry_Nyquist
https://en.wikipedia.org/wiki/Nyquist–Shannon_sampling_theorem
https://en.wikipedia.org/wiki/Nyquist_frequency
https://en.wikipedia.org/wiki/Nyquist_rate