John Peter Costas (1923 in

Wabash, Indiana Wabash is a city in Noble Township, Wabash County, Indiana, Noble Township, Wabash County, Indiana, Wabash County, in the U.S. state of Indiana. The population was 10,666 at the 2010 census. The city is situated along the Wabash River in the cou ...

– August 9, 2008) was an American

electrical engineer Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

. Costas invented, among other things, the

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

and

Costas array In mathematics, a Costas array can be regarded geometry, 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''& ...

Biography

Costas studied at

Purdue University Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...

as an undergraduate. During

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, he was involved in

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

engineering, serving in the

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Department of Defense. It is the world's most powerful navy with the largest displacement, at 4.5 million tons in 2021. It has the world's largest aircraft ...

as a radar officer. He was a graduate student at

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

(MIT), where he worked on interference filtering and linear systems coding. While there, he worked with

Norbert Wiener Norbert Wiener (November 26, 1894 – March 18, 1964) was an American computer scientist, mathematician, and philosopher. He became a professor of mathematics at the Massachusetts Institute of Technology ( MIT). A child prodigy, Wiener late ...

, R. M. Fano, J. B. Wiesner and Y. W. Lee. He worked for

General Electric General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the year ...

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 fixed relative to the phase of an input signal. Keeping the input and output phase in lockstep also implies keeping the input and ou ...

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 The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE has a corporate office ...

(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 Fellows of the IEEE General Electric people Fellows of the American Association for the Advancement of Science 20th-century American engineers 20th-century American inventors