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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Bell prototype telephone stamp(from History of the telephone)
Centennial Issue of 1976 -
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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) -
Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876. (from History of the telephone) -
Thomas Edison invented the carbon microphone which produced a strong telephone signal. (from History of the telephone) -
Caricature of Sir John Reith, by Wooding (from History of broadcasting) -
The first mass-produced Czechoslovak TV-set Tesla 4001A (1953–57) (from History of television) -
Charles Logwood broadcasting at station 2XG, New York City, circa November, 1916 (from History of broadcasting) -
First television test broadcast transmitted by the NHK Broadcasting Technology Research Institute in May 1939 (from History of television) -
The 1969 AT&T Mod II Picturephone, the result of decades long R&D at a cost of over $500M. (from History of telecommunication) -
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 Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis (from History of television) -
Right side view, housing removed, one of its printed circuit boards exposed (courtesy: Richard Diehl) (from History of videotelephony) -
AT&T magazine advertisement announcing commercial launch of Picturephone service. (from History of videotelephony) -
Antonio Meucci, 1854, developed a voice-communication apparatus that several sources credit as the first telephone. (from History of the telephone) -
Receiver schematic, c.1906 (from History of the telephone) -
An exposed view of the Picturephone's rear circuit board (courtesy: Richard Diehl) (from History of videotelephony) -
Top of cellular telephone tower (from History of the telephone) -
RCA 630-TS, the first mass-produced television set, which sold in 1946–1947 (from History of television) -
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Family watching TV, 1958 (from History of television) -
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) -
Philo Farnsworth in 1924 (from History of television) -
Broadcasting pioneer Frank Conrad in a 1921 portrait (from History of broadcasting) -
Color bars used in a test pattern, sometimes used when no program material is available (from History of television) -
Reis's telephone around 1861, first device called telephone (from History of the telephone) -
1917 wall telephone, open to show magneto and local battery (from History of the telephone) -
Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
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The master telephone patent, 174465, granted to Bell, March 7, 1876 (from History of telecommunication) -
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) -
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) -
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) -
Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation. (from History of radio) -
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) -
Typical low-cost webcam used with many personal computers (from History of videotelephony) -
Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia) (from History of telecommunication) -
"Doc" Herrold is shown at the microphone of KQW, early 1920s. (from History of broadcasting) -
An early Smart TV from 2012 running the discontinued Orsay platform (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) -
Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves. (from History of radio) -
Reginald Fessenden, the "father" of radio broadcasting in the US (from History of broadcasting) -
Ad for the beginning of experimental television broadcasting in New York City by RCA in 1939 (from History of television) -
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Manfred von Ardenne in 1933 (from History of television) -
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) -
The Australian Broadcasting Corporation logo, first introduced in 1975 and based on the Lissajous curve (from History of broadcasting) -
The French Matra videophone (1970) (from History of videotelephony) -
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) -
Guglielmo Marconi (from History of broadcasting) -
A 19th century acoustic tin can or "lovers' telephone" (from History of the telephone) -
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) -
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Private conversation, 1910 (from History of the telephone) -
British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio) -
Reginald Fessenden (around 1906) (from History of radio) -
"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) -
Naomi ("Joan") Melwit and Norman Banks at the 3KZ microphone, in the late 1930s (from History of broadcasting) -
The "Kerbango Internet Radio" was the first stand-alone product that let users listen to Internet radio without a computer. (from History of broadcasting) -
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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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) -
The master telephone patent granted to Bell, 174465, March 7, 1876 (from History of the telephone)
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Historical marker commemorating the first telephone central office in New York State (1878) (from History of the telephone) -
Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897 (from History of radio) -
Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. (from History of the telephone) -
Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. (from History of the telephone) -
Reconstruction of Aeneas Tacticus' hydraulic telegraph (4th c. B.C.) in Kotsanas Museum of Ancient Greek Technology, Athens, Greece. (from History of telecommunication) -
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) -
Artist's conception: 21st-century videotelephony imagined in the early 20th century (1910) (from History of videotelephony) -
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) -
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Apple iPhone smartphone (from History of the telephone) -
A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris (from History of the telephone) -
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) -
A replica of one of Claude Chappe's semaphore towers (optical telegraph) in Nalbach, Germany (from History of telecommunication) -
Baird in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" (right) (from History of television) -
Tihanyi' Radioskop patent (1926) was recognized as Document of Universal Significance by the UNESCO (from History of television)
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Selected biography -
Philo Taylor Farnsworth (August 19, 1906 – March 11, 1971), "The father of television", was the American inventor and pioneer who was granted the first patent for the television by the United States Government.
He also invented a video camera tube, and the image dissector. He commercially produced and sold a fully functioning 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. (Full article...)
Did you know (auto-generated) -
- ... that One Chun, a Michelin Guide Bib Gourmand restaurant, has black-and-white televisions, transistor radios, and aged clocks on a wall?
- ... that a regional radio group with 75 stations started with a "Big Wrig"?
- ... that the Japanese live-action television drama adaptation of Accomplishment of Fudanshi Bartender was first broadcast in Taiwan before being broadcast in its home country?
- ... that a government surplus audio console used by a Virginia radio station was believed to have been used to broadcast Franklin D. Roosevelt's fireside chats?
- ... that Seattle radio station KBLE was named in 1963 for a cable car system that had closed nearly 25 years prior?
- ... that BBC radio broadcaster Venu Chitale taught listeners how to cook without meat when it was rationed during the Second World War?
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