Portal:Telecommunication
The Telecommunication Portal
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions. Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph, telephone, television, and radio.
Early telecommunication networks used metal wires as the medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi, who won the 1909 Nobel Prize in Physics. Other early pioneers in electrical and electronic telecommunications include co-inventors of the telegraph Charles Wheatstone and Samuel Morse, numerous inventors and developers of the telephone including Antonio Meucci, Philipp Reis, Elisha Gray and Alexander Graham Bell, inventors of radio Edwin Armstrong and Lee de Forest, as well as inventors of television like Vladimir K. Zworykin, John Logie Baird and Philo Farnsworth.
Since the 1960s, the proliferation of digital technologies has meant that voice communications have gradually been supplemented by data. The physical limitations of metallic media prompted the development of optical fibre. The Internet, a technology independent of any given medium, has provided global access to services for individual users and further reduced location and time limitations on communications. (Full article...)
Selected article -
In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission used in digital modulation for encoding digital (binary) data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL internet access, wireless networks, power line networks, and 4G/5G mobile communications.
OFDM is a frequency-division multiplexing (FDM) scheme that was introduced by Robert W. Chang of Bell Labs in 1966. In OFDM, the incoming bitstream representing the data to be sent is divided into multiple streams. Multiple closely spaced orthogonal subcarrier signals with overlapping spectra are transmitted, with each carrier modulated with bits from the incoming stream so multiple bits are being transmitted in parallel. Demodulation is based on fast Fourier transform algorithms. OFDM was improved by Weinstein and Ebert in 1971 with the introduction of a guard interval, providing better orthogonality in transmission channels affected by multipath propagation. Each subcarrier (signal) is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase-shift keying) at a low symbol rate. This maintains total data rates similar to conventional single-carrier modulation schemes in the same bandwidth. (Full article...)
General images
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First television test broadcast transmitted by the NHK Broadcasting Technology Research Institute in May 1939 (from History of television) -
Thomas Edison invented the carbon microphone which produced a strong telephone signal. (from History of the telephone) -
Typical low-cost webcam used with many personal computers (from History of videotelephony) -
RCA 630-TS, the first mass-produced television set, which sold in 1946–1947 (from History of television) -
The "Kerbango Internet Radio" was the first stand-alone product that let users listen to Internet radio without a computer. (from History of broadcasting) -
Family watching TV, 1958 (from History of television) -
Caricature of Sir John Reith, by Wooding (from History of broadcasting) -
Guglielmo Marconi (from History of broadcasting) -
AT&T magazine advertisement announcing commercial launch of Picturephone service. (from History of videotelephony) -
The first commercial AM Audion vacuum tube radio transmitter, built in 1914 by Lee De Forest who invented the Audion (triode) in 1906 (from History of radio) -
Manfred von Ardenne in 1933 (from History of television) -
Naomi ("Joan") Melwit and Norman Banks at the 3KZ microphone, in the late 1930s (from History of broadcasting) -
Replica of the telettrofono at Museo Nazionale Scienza e Tecnologia Leonardo da Vinci of Milan, Italy, invented by Antonio Meucci and credited by several sources as the first telephone. (from History of the telephone) -
Reginald Fessenden (around 1906) (from History of radio) -
The Nipkow disk. This schematic shows the circular paths traced by the holes, which may also be square for greater precision. The area of the disk outlined in black shows the region scanned. (from History of television) -
A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris (from History of the telephone) -
Broadcasting pioneer Frank Conrad in a 1921 portrait (from History of broadcasting) -
Top of cellular telephone tower (from History of the telephone) -
Tihanyi' Radioskop patent (1926) was recognized as Document of Universal Significance by the UNESCO (from History of television) -
In the 1920s, the United States government publication, "Construction and Operation of a Simple Homemade Radio Receiving Outfit", showed how almost any person handy with simple tools could a build an effective crystal radio receiver. (from History of radio) -
The Marconi Company was formed in England in 1910. The photo shows a typical early scene, from 1906, with Marconi employee Donald Manson at right. (from History of broadcasting) -
The Kyocera VP-210 Visual Phone was the first commercial mobile videophone. The Personal Handy-phone System (PHS) phone was introduced in Japan (1999). (from History of videotelephony) -
Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897 (from History of radio) -
A 19th century acoustic tin can or "lovers' telephone" (from History of the telephone) -
The master telephone patent, 174465, granted to Bell, March 7, 1876 (from History of telecommunication) -
Receiver schematic, c.1906 (from History of the telephone) -
Ad for the beginning of experimental television broadcasting in New York City by RCA in 1939 (from History of television) -
Historical marker commemorating the first telephone central office in New York State (1878) (from History of the telephone) -
The Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis (from History of television) -
Apple iPhone smartphone (from History of the telephone) -
The 1969 AT&T Mod II Picturephone, the result of decades long R&D at a cost of over $500M. (from History of telecommunication) -
Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. (from History of the telephone) -
The Regency TR-1, which used Texas Instruments' NPN transistors, was the world's first commercially produced transistor radio in 1954. Size: 3×5×1.25 inch (7.6×12.7×3.2 cm) (from History of radio) -
1917 wall telephone, open to show magneto and local battery (from History of the telephone) -
Around 1920, radio broadcasting started to get popular. The Brox Sisters, a popular singing group, gathered around the radio at the time. (from History of radio) -
"Doc" Herrold is shown at the microphone of KQW, early 1920s. (from History of broadcasting) -
Emil Voigt, founder of 2KY on behalf of the Labor Council of New South Wales. This photo was taken in earlier days when Voight was a prominent British athlete, and winner of the Gold Medal for the five mile race at the 1908 Summer Olympics in London. (from History of broadcasting) -
Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia) (from History of telecommunication) -
Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves. (from History of radio) -
Early pioneers of radio science and technology in the United States including Charles Steinmetz, David Sarnoff, Irving Langmuir and Alfred Goldsmith in 1921, photographed next to the antenna feed wires of the New Brunswick Marconi Station, one of the first transatlantic radio links. Photo includes Albert Einstein as a visiting guest. (from History of radio) -
Reconstruction of Aeneas Tacticus' hydraulic telegraph (4th c. B.C.) in Kotsanas Museum of Ancient Greek Technology, Athens, Greece. (from History of telecommunication) -
"Fiction becomes fact": Imaginary "Edison" combination videophone-television, conceptualized by George du Maurier and published in Punch magazine. The drawing also depicts then-contemporary speaking tubes, used by the parents in the foreground and their daughter on the viewing display (1878). (from History of videotelephony) -
Lee DeForest broadcasting Columbia phonograph records on pioneering New York station 2XG, in 1916 (from History of broadcasting) -
Bell prototype telephone stamp(from History of the telephone)
Centennial Issue of 1976 -
The first mass-produced Czechoslovak TV-set Tesla 4001A (1953–57) (from History of television) -
The master telephone patent granted to Bell, 174465, March 7, 1876 (from History of the telephone)
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An early Smart TV from 2012 running the discontinued Orsay platform (from History of television) -
Color bars used in a test pattern, sometimes used when no program material is available (from History of television) -
Reginald Fessenden, the "father" of radio broadcasting in the US (from History of broadcasting) -
An exposed view of the Picturephone's rear circuit board (courtesy: Richard Diehl) (from History of videotelephony) -
Private conversation, 1910 (from History of the telephone) -
Philo Farnsworth in 1924 (from History of television) -
Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
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Antonio Meucci, 1854, developed a voice-communication apparatus that several sources credit as the first telephone. (from History of the telephone) -
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The earliest photograph of a television picture, showing the face of Oliver Hutchinson in June 1926. The television picture was projected using Baird's television camera. (from History of television) -
The Australian Broadcasting Corporation logo, first introduced in 1975 and based on the Lissajous curve (from History of broadcasting) -
A replica of one of Claude Chappe's semaphore towers (optical telegraph) in Nalbach, Germany (from History of telecommunication) -
Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. (from History of the telephone) -
DBS satellite dishes (from History of television) -
Australian radio sets usually had the positions of radio stations marked on their dials. The illustration is a dial from a transistorised, mains-operated Calstan radio, circa 1960s. (Click image for a high resolution view, with readable callsigns.) (from History of broadcasting) -
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The French Matra videophone (1970) (from History of videotelephony) -
AT&T Picturephone (Mod II) fully enclosed in its housing, control pad at bottom (courtesy: Richard Diehl) (from History of videotelephony)
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Reis's telephone around 1861, first device called telephone (from History of the telephone) -
Right side view, housing removed, one of its printed circuit boards exposed (courtesy: Richard Diehl) (from History of videotelephony) -
British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio) -
Charles Logwood broadcasting at station 2XG, New York City, circa November, 1916 (from History of broadcasting) -
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1896 telephone (Sweden) (from History of the telephone) -
Actor portraying Alexander Graham Bell in a 1932 silent film. Shows Bell's second telephone transmitter (microphone), invented 1876 and first displayed at the Centennial Exposition, Philadelphia. (from History of the telephone) -
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Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation. (from History of radio) -
Artist's conception: 21st-century videotelephony imagined in the early 20th century (1910) (from History of videotelephony) -
Baird in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" (right) (from History of television) -
Swedish Prime Minister Tage Erlander using an Ericsson videophone to speak with Lennart Hyland, a popular TV show host (1969) (from History of videotelephony) -
Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876. (from History of the telephone) -
The British Broadcasting Corporation's landmark and iconic London headquarters, Broadcasting House, opened in 1932. At right is the 2005 eastern extension, the John Peel wing. (from History of broadcasting) -
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Selected biography -
Philo Taylor Farnsworth (August 19, 1906 – March 11, 1971) was an American inventor and television pioneer. He made the critical contributions to electronic television that made possible modern electronic video. He is best known for his 1927 invention of the first fully functional all-electronic image pickup device (video camera tube), the image dissector, as well as the first fully functional and complete all-electronic television system. Farnsworth developed a television system complete with receiver and camera—which he produced commercially through the Farnsworth Television and Radio Corporation from 1938 to 1951, in Fort Wayne, Indiana.
In later life, Farnsworth invented a small nuclear fusion device, the Farnsworth Fusor, employing inertial electrostatic confinement (IEC). Like many fusion devices, it was not a practical device for generating nuclear power, although it provides a viable source of neutrons. The design of this device has been the inspiration for other fusion approaches, including the Polywell reactor concept. Farnsworth held 300 patents, mostly in radio and television. (Full article...)
Did you know (auto-generated) -
- ... that actor Tatsunari Kimura ate pancakes and drank coffee while talking for eight hours during the filming of the television drama Old-Fashioned Cupcake?
- ... that the hashtag #AlDubEBTamangPanahon set a Guinness World Record in 2015 with 40,706,392 uses in 24 hours, coinciding with the television event "Tamang Panahon"?
- ... that Sunday-school classes were once held in the transmitter building of New Mexico radio station KCLV?
- ... that a woman hitchhiked from Indiana to Washington, D.C., to protest the sale of the radio station where she worked?
- ... that 1920s and 1930s radio show actress Artie Belle McGinty played the original radio advertisement voice for Aunt Jemima?
- ... that the church that attempted to sell a Kansas radio station could not locate the money allegedly paid by the buyer?
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