The Carson twins, from the Class of 1907 album

John Renshaw Carson (June 28, 1886 – October 31, 1940) was an American transmission theorist for early communications systems. He invented

single-sideband modulation In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude modul ...

and developed the

Carson bandwidth rule In telecommunication, Carson's bandwidth rule defines the approximate bandwidth requirements of communications system components for a carrier signal that is frequency modulated by a continuous or broad spectrum of frequencies rather than a single ...

for estimating

frequency modulation Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and computing. In analog ...

(FM) bandwidth. In 2013 Carson was inducted into the Electronic Design Hall of Fame for his contributions to communications.

Biography

Albert Einstein with other engineers and scientists at Marconi RCA radio station 1921

Carson was born in

Pittsburgh, Pennsylvania Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

, and together with his twin brother Joseph attended

Princeton University Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ...

, graduating in 1907 with a Bachelor of Science degree. John attended the

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 th ...

1907–1908, before returning to Princeton to receive his

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

degree in 1909 and a Master of Science degree in 1912. From 1912 to 1914 Carson was an instructor in Electrical Engineering and Physics at Princeton, but in 1913 was offered a position at

American Telephone & Telegraph AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agen ...

(AT&T), and in 1914 left the university. At AT&T, Carson was involved in early radio telephone experiments. In 1915 he invented

to transmit multiple telephone calls simultaneously on a single electrical circuit, and was responsible for installing the first such system between

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

and

Baltimore Baltimore ( , locally: or ) is the most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic, and the 30th most populous city in the United States with a population of 585,708 in 2020. Baltimore was ...

. In 1922 he published a mathematical treatment of

(FM), which introduced the

. In his 1922 paper, Carson presented a negative opinion of narrowband FM, which occurs when the maximum frequency swing is made narrower than the audio bandwidth. Later,

Edwin Armstrong Edwin Howard Armstrong (December 18, 1890 – February 1, 1954) was an American electrical engineer and inventor, who developed FM (frequency modulation) radio and the superheterodyne receiver system. He held 42 patents and received numerous awa ...

managed to demonstrate that FM can be advantageous if the frequency swing is significantly wider than the audio bandwidth. From 1917 to 1925 Carson analyzed the effects of filters on

amplitude modulation Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to ...

via

operational calculus Operational calculus, also known as operational analysis, is a technique by which problems in analysis, in particular differential equations, are transformed into algebraic problems, usually the problem of solving a polynomial equation. History Th ...

, thus allowing telephone system designers to predict

crosstalk In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, i ...

in multiple calls over a single pair of wires. He published a series of papers on this subject in the

Bell System Technical Journal The ''Bell Labs Technical Journal'' is the in-house scientific journal for scientists of Nokia Bell Labs, published yearly by the IEEE society. The managing editor is Charles Bahr. The journal was originally established as the ''Bell System Tech ...

, culminating in his 1926 book ''Electrical Circuit Theory and Operational Calculus''. From 1925 to 1940 Carson worked for

Bell Telephone Laboratories Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

as a mathematician and electrical engineer. Notable work during this era included his mathematical analysis of George C. Southworth's 1932

waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...

experiments. Carson received the 1924 IRE Morris N. Liebmann Memorial Award "in recognition of his valuable contributions to alternating current circuit theory and, in particular, to his investigations of filter systems and of single side band telephony." He received an honorary Doctor of Science degree from

Brooklyn Polytechnic Institute The New York University Tandon School of Engineering (commonly referred to as Tandon) is the engineering and applied sciences school of New York University. Tandon is the second oldest private engineering and technology school in the United St ...

in 1937, and the 1939

Elliott Cresson Medal The Elliott Cresson Medal, also known as the Elliott Cresson Gold Medal, was the highest award given by the Franklin Institute. The award was established by Elliott Cresson, life member of the Franklin Institute, with $1,000 granted in 1848. The ...

from the

Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memori ...

. His undergraduate letters are archived at

Patent

* : John Carson/AT&T: "Method and Means for Signaling with High Frequency Waves" filed on December 1, 1915; granted on March 27, 1923

Selected works

* 1921: "Wave Propagation over Parallel Wires: The Proximity effect", ''Philosophical Magazine'', volume IXLI, pages 607–633. * 1922: "Notes on the Theory of Modulation", ''Proceedings of the Institute of Radio Engineers'', volume 10, issue 1, pages 57–64. * 1924
A Generalization of Reciprocal Theorem

3: 393–399. * 1925
Selective Circuits and Static Interference
''Bell System Technical Journal'', 4:265. * 1926
Wave Propagation in Overhead Wires with Ground Return
''Bell System Technical Journal'', 5: 539. * 1926: ''Electrical Circuit Theory and Operational Calculus'', New York : McGraw–Hill. * 1926
The Heaviside Operational Calculus

Bulletin of the American Mathematical Society The ''Bulletin of the American Mathematical Society'' is a quarterly mathematical journal published by the American Mathematical Society. Scope It publishes surveys on contemporary research topics, written at a level accessible to non-experts. ...

32(1):43–68, link from

Project Euclid Project Euclid is a collaborative partnership between Cornell University Library and Duke University Press which seeks to advance scholarly communication in theoretical and applied mathematics and statistics through partnerships with independent an ...

. * 1936: (with S. P. Mead and S. A. Schelkunoff
Hyper-Frequency Waveguides: Mathematical Theory
''Bell System Technical Journal'' 15: 310–333.

References

Sources

John & Robb Carson Letters
in Mudd Manuscript Library of

Princeton University Library Princeton University Library is the main library system of Princeton University. With holdings of more than 7 million books, 6 million microforms, and 48,000 linear feet of manuscripts, it is among the largest libraries in the world by number of ...

Archives. * Brittain, J.E., "John R. Carson and the conservation of radio spectrum", ''Proceedings of the IEEE'', volume 84, issue 6, June 1996, pages 909–910. * Mario Lucertini, Ana Millán Gasca, F. Nicolò, ''Technological Concepts and Mathematical Models in the Evolution of Modern Engineering Systems'', Birkhäuser, 2004, pages 114–117. . * Julie K. Petersen, ''Fiber Optics Illustrated Dictionary'', CRC Press, 2003, page 264. . {{DEFAULTSORT:Carson, John R. American telecommunications engineers 1886 births 1940 deaths Radio pioneers Scientists at Bell Labs

Biography

Patent

Selected works

See also

References

Sources