Portal:Telecommunication
The Telecommunication Portal
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information with an immediacy comparable to face-to-face communication. As such, slow communications technologies like postal mail and pneumatic tubes are excluded from the definition. Many transmission media have been used for telecommunications throughout history, from smoke signals, beacons, semaphore telegraphs, signal flags, and optical heliographs to wires and empty space made to carry electromagnetic signals. These paths of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions. Several methods of long-distance communication before the modern era used sounds like coded drumbeats, the blowing of horns, and whistles. 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 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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Caricature of Sir John Reith, by Wooding (from History of broadcasting) -
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) -
DBS satellite dishes (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) -
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Antonio Meucci, 1854, constructed telephone-like devices. (from History of the telephone) -
Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876. (from History of the telephone) -
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) -
Apple iPhone smartphone (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) -
British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio) -
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) -
1917 wall telephone, open to show magneto and local battery (from History of the telephone) -
An early Smart TV from 2012 running the discontinued Orsay platform (from History of television) -
Family watching TV, 1958 (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) -
A replica of one of Claude Chappe's semaphore towers (optical telegraph) in Nalbach, Germany (from History of telecommunication) -
Reginald Fessenden (around 1906) (from History of radio) -
Artist's conception: 21st-century videotelephony imagined in the early 20th century (1910) (from History of videotelephony) -
Thomas Edison invented the carbon microphone which produced a strong telephone signal. (from History of the telephone) -
The first mass-produced Czechoslovak TV-set Tesla 4001A (1953–57) (from History of television) -
"Doc" Herrold is shown at the microphone of KQW, early 1920s. (from History of broadcasting) -
Broadcasting pioneer Frank Conrad in a 1921 portrait (from History of broadcasting) -
Old Receiver schematic, c.1906 (from History of the telephone) -
Reginald Fessenden, the "father" of radio broadcasting in the US (from History of broadcasting) -
The Regency TR-1, which used Texas Instruments' NPN transistors, was the world's first commercially produced transistor radio in 1954. (from History of radio) -
Naomi ("Joan") Melwit and Norman Banks at the 3KZ microphone, in the late 1930s (from History of broadcasting) -
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Guglielmo Marconi (from History of broadcasting) -
The Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis (from History of television) -
First television test broadcast transmitted by the NHK Broadcasting Technology Research Institute in May 1939 (from History of television) -
Antonio Meucci's telephone. (from History of the telephone) -
Typical low-cost webcam used with many personal computers (from History of videotelephony) -
Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897 (from History of radio) -
Ad for the beginning of experimental television broadcasting in New York City by RCA in 1939 (from History of television) -
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) -
RCA 630-TS, the first mass-produced television set, which sold in 1946–1947 (from History of television) -
"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) -
Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves. (from History of radio) -
Top of cellular telephone tower (from History of the telephone) -
Baird in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" (right) (from History of television) -
1896 Telephone (Sweden) (from History of the telephone) -
Manfred von Ardenne in 1933 (from History of television) -
The master telephone patent, 174465, granted to Bell, March 7, 1876 (from History of telecommunication) -
Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. (from History of the telephone) -
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) -
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) -
Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. (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) -
Philo Farnsworth in 1924 (from History of television) -
Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia) (from History of telecommunication) -
The French Matra videophone (1970) (from History of videotelephony) -
The master telephone patent granted to Bell, 174465, March 10, 1876 (from History of the telephone)
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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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Bell prototype telephone stamp(from History of the telephone)
Centennial Issue of 1976 -
The Australian Broadcasting Corporation logo, first introduced in 1975 and based on the Lissajous curve (from History of broadcasting) -
A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris (from History of the telephone) -
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Charles Logwood broadcasting at station 2XG, New York City, circa November, 1916 (from History of broadcasting) -
Color bars used in a test pattern, sometimes used when no program material is available (from History of television) -
Lee DeForest broadcasting Columbia phonograph records on pioneering New York station 2XG, in 1916 (from History of broadcasting) -
Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio) -
Right side view, housing removed, one of its printed circuit boards exposed (courtesy: Richard Diehl) (from History of videotelephony) -
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) -
Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation. (from History of radio) -
Private conversation, 1910 (from History of the telephone) -
Historical marker commemorating the first telephone central office in New York State (1878) (from History of the telephone) -
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An exposed view of the Picturephone's rear circuit board (courtesy: Richard Diehl) (from History of videotelephony) -
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AT&T magazine advertisement announcing commercial launch of Picturephone service. (from History of videotelephony) -
A 19th century acoustic tin can or "lovers' telephone" (from History of the telephone) -
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)
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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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Selected biography -
Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi GCVO FRSA (Italian: [ɡuʎˈʎɛlmo marˈkoːni]; 25 April 1874 – 20 July 1937) was an Italian inventor, electrical engineer, physicist, and politician, known for his creation of a practical radio wave–based wireless telegraph system. This led to Marconi being credited as the inventor of radio, and winning the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy". His work laid the foundation for the development of radio, television, and all modern wireless communication systems.
Marconi was also an entrepreneur, businessman, and founder of The Wireless Telegraph & Signal Company in the United Kingdom in 1897 (which became the Marconi Company). In 1929, Marconi was ennobled as a Marchese (marquis) by King Victor Emmanuel III of Italy, and, in 1931, he set up Vatican Radio for Pope Pius XI. (Full article...)Did you know (auto-generated) -
- ... that a Catholic radio station in Texas airs religious talk shows, the Mass—and weekly broadcasts of high school football?
- ... that before pursuing a career in music, Lauren Jenkins was the host of a wrestling television show?
- ... that an Alabama radio station was described by its program director as a "no-format mess"?
- ... that a complaint over an allegedly illegal transmitter move led to Texas radio station KFQX-FM being forced off the air for four hours in 1988?
- ... that the telephone exchange in Craig's Court contains one of the entrances to the secret government tunnels under London?
- ... that in Jackson, Tennessee, there was a 50–50 chance a reference to Dixie was about a radio station?
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