John Peter Costas (1923 in

Wabash, Indiana Wabash is a city in Noble Township, Wabash County, in the U.S. state of Indiana. The population was 10,666 at the 2010 census. The city is the county seat of Wabash County. Wabash is notable as claiming to be the first electrically lighted ci ...

– August 9, 2008) was an American electrical engineer. Costas invented, among other things, the

Costas loop A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It w ...

and

Costas array In mathematics, a Costas array can be regarded geometrically as a set of ''n'' points, each at the center of a square in an ''n''×''n'' square tiling such that each row or column contains only one point, and all of the ''n''(''n'' &minu ...

Biography

Costas studied at

Purdue University Purdue University is a public land-grant research university in West Lafayette, Indiana, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and mone ...

as an undergraduate. During

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

, he was involved in

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

engineering, serving in the

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...

as a radar officer. He was a graduate student at

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

(MIT), where he worked on interference filtering and linear systems coding. While there, he worked with Norbert Wiener, R. M. Fano, J. B. Wiesner and Y. W. Lee. He worked for

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable en ...

from 1951 until the early 1980s, and for Cogent Systems, Inc. He was retired since then, and died on August 9, 2008.

Work

Costas is probably best known for his 1950s invention of the

, a modified

phase locked loop A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input signal. There are several different types; the simplest is an electronic circuit consisting of a ...

that recovers the "suppressed" carrier in many digital communications receivers. It had "a profound effect on modern digital communications" In the 1960s, he helped solve the mystery concerning poor performance of sonar systems. He found that the rapidly time-varying channel made coherent processing inappropriate. His solution involved a kind of permutation array, now known as a

, which has ideal properties for the problem. Costas was made a fellow of the Institute of Electrical and Electronics Engineers (IEEE) in 1965 for "contributions to communications theory and techniques."

Publications

Among Costas' most notable publications are the following, * 1984, "A Study of a Class of Detection Waveforms Having Nearly Ideal Range-Doppler Ambiguity Properties" in ''Proc. IEEE, vol. 72, no. 8, pp.996-1009, Aug. 1984''. * 1975 "Medium constraints on sonar design and performance". Technical Report Class 1 Rep. R65EMH33, GE Co., 1965. a synopsis of this report appeared in the Eascon. Conv. Rec., 1975, pp. 68A—68L * 1966 "Project Medior – A medium-oriented approach to sonar signal processing". ''Lockheed Martin Marine Systems and Sensors'', 1966. * 1956 "Synchronous Communications". In ''Proceedings of the IEEE'', December 1956. Republished in same journal in Vol 90, no. 8, August 2002 as classic paper.

References

External links

– ''Open Problems in Costas Arrays'', S. Rickard. * {{DEFAULTSORT:Costas, John P. 1923 births 2008 deaths American electrical engineers MIT School of Engineering alumni People from Wabash, Indiana Purdue University College of Engineering alumni Fellow Members of the IEEE General Electric people Fellows of the American Association for the Advancement of Science 20th-century American engineers 20th-century American inventors