Harry Theodor Nyquist (pronounced "nigh-kwist" in English and [ˈnŷːkvɪst] in Swedish), born on February 7, 1889, and died on April 4, 1976, was a Swedish-American physicist and electronic engineer. He made important contributions to communication theory.
Personal life
Nyquist was born in the village of Nilsby, located in the parish of Stora Kil, Värmland, Sweden. He was the son of Lars Jonsson Nyqvist (1847–1930) and Catarina (or Katrina) Eriksdotter (1857–1920). His parents had eight children: Elin Teresia, Astrid, Selma, Harry Theodor, Amelie, Olga Maria, Axel Martin, and Herta Alfrida. He immigrated to the United States in 1907.
Education
He began his studies at the University of North Dakota in 1912. He earned a bachelor's degree and a master's degree in electrical engineering in 1914 and 1915. In 1917, he received a Ph.D. in physics from Yale University.
Career
Harry Nyquist worked at AT&T's Department of Development and Research from 1917 to 1934. When the department became Bell Telephone Laboratories in 1934, he continued his work there until he retired in 1954.
In 1960, Nyquist received the IRE Medal of Honor for "fundamental contributions to a quantitative understanding of thermal noise, data transmission, and negative feedback." In October 1960, he was also awarded the Stuart Ballantine Medal by the Franklin Institute "for his theoretical analyses and practical inventions in the field of communications systems during the past forty years, including his original work in the theories of telegraph transmission, thermal noise in electric conductors, and the history of feedback systems." In 1969, he received the National Academy of Engineering's fourth Founder's Medal "in recognition of his many fundamental contributions to engineering." In 1975, Nyquist shared the Rufus Oldenburger Medal from the American Society of Mechanical Engineers with Hendrik Bode.
As reported in The Idea Factory: Bell Labs and the Great Age of American Innovation, Bell Labs patent lawyers studied why some employees produced more patents than others. After analyzing data, they found that productive employees often shared meals with a Bell Labs electrical engineer named Harry Nyquist. It was not because Nyquist gave them specific ideas, but because he encouraged others to think and share ideas.
After retiring, Nyquist lived in Pharr, Texas. He died in Harlingen, Texas, on April 4, 1976.
Technical contributions
Harold Nyquist worked as an engineer at Bell Laboratories, where he made important contributions to understanding thermal noise, called "Johnson–Nyquist noise," and the stability of feedback amplifiers. He also worked on telegraphy, facsimile, television, and other communication challenges. With Herbert E. Ives, he helped create AT&T's first public facsimile machines in 1924. In 1932, he wrote an important paper about the stability of feedback amplifiers. Today, the Nyquist stability criterion is included in many textbooks about feedback control theory.
Nyquist’s early work on how much bandwidth is needed to send information helped later research by Claude Shannon, which led to the development of information theory. He discovered that the number of independent pulses that can be sent through a telegraph channel each second is limited to twice the channel’s bandwidth. He shared these findings in two papers: "Certain factors affecting telegraph speed" (1924) and "Certain topics in Telegraph Transmission Theory" (1928). This rule is closely related to a principle now called the Nyquist–Shannon sampling theorem.
Terms named for Harry Nyquist
- Nyquist rate: the sampling speed that is double the signal's waveform bandwidth; sampling at this speed or faster allows the waveform to be recreated accurately.
- Nyquist frequency: one-half of a system's sampling rate; signal frequencies below this value are shown clearly without confusion.
- Nyquist filter
- Nyquist plot
- Nyquist ISI criterion
- Nyquist (programming language)
- Nyquist stability criterion