Harry Nyquist

Harry Nyquist ( pronunciation: [ nʏ: kvɪst ], not [ naɪkwɪst ] ) ( born February 7, 1889 in Nilsby, Sweden, † April 4, 1976 in Harlingen, Texas ) was an American physicist. He made ​​an important contribution to information theory.

Harry Nyquist was born in Nilsby in Sweden and emigrated in 1907 to the United States. He studied physics at the University of North Dakota and received his PhD in 1917 at Yale University. He worked at AT & T and later at Bell Laboratories.

His first studies were concerned with the thermal noise (Johnson - Nyquist noise) and with the stability of feedback amplifier. Furthermore, he studied the bandwidth required for transmitting information. In 1927, he found that an analog signal with more than twice the signal frequency must be sampled in order to reconstruct the digital image of the signal, the analog output signal can. Nyquist published his results in 1928 under the title Certain topics in Telegraph Transmission Theory, now known as the Nyquist -Shannon sampling theorem.

Nyquist's sampling theorem and its exploration of the required bandwidth constituted an important basis for Claude Shannon's theoretical work that eventually led to the creation of information theory.

No less important is Nyquist's contribution to the control technology; He coined the terms Nyquist plot ( locus ), Nyquist and Nyquist criterion.