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The Telecommunication Portal
Telecommunication, often used in its plural form, 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...)
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A transmission medium is a system or substance that can mediate the propagation of signals for the purposes of telecommunication. Signals are typically imposed on a wave of some kind suitable for the chosen medium. For example, data can modulate sound, and a transmission medium for sounds may be air, but solids and liquids may also act as the transmission medium. Vacuum or air constitutes a good transmission medium for electromagnetic waves such as light and radio waves. While a material substance is not required for electromagnetic waves to propagate, such waves are usually affected by the transmission media they pass through, for instance, by absorption or reflection or refraction at the interfaces between media. Technical devices can therefore be employed to transmit or guide waves. Thus, an optical fiber or a copper cable is used as transmission media.
Electromagnetic radiation can be transmitted through an optical medium, such as optical fiber, or through twisted pair wires, coaxial cable, or dielectric-slab waveguides. It may also pass through any physical material that is transparent to the specific wavelength, such as water, air, glass, or concrete. Sound is, by definition, the vibration of matter, so it requires a physical medium for transmission, as do other kinds of mechanical waves and heat energy. Historically, science incorporated various aether theories to explain the transmission medium. However, it is now known that electromagnetic waves do not require a physical transmission medium, and so can travel through the vacuum of free space. Regions of the insulative vacuum can become conductive for electrical conduction through the presence of free electrons, holes, or ions. (Full article...)General images
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British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio) -
Bell prototype telephone stamp(from History of the telephone)
Centennial Issue of 1976 -
Right side view, housing removed, one of its printed circuit boards exposed (courtesy: Richard Diehl) (from History of videotelephony) -
The French Matra videophone (1970) (from History of videotelephony) -
Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia) (from History of telecommunication) -
Antonio Meucci's telephone. (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) -
The master telephone patent, 174465, granted to Bell, March 7, 1876 (from History of telecommunication) -
Broadcasting pioneer Frank Conrad in a 1921 portrait (from History of broadcasting) -
Old Receiver schematic, c.1906 (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) -
Ad for the beginning of experimental television broadcasting in New York City by RCA in 1939 (from History of television) -
Family watching TV, 1958 (from History of television) -
Guglielmo Marconi (from History of broadcasting) -
Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. (from History of the telephone) -
DBS satellite dishes. (from History of television) -
The Australian Broadcasting Corporation logo, first introduced in 1975 and based on the Lissajous curve (from History of broadcasting) -
"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) -
Thomas Edison invented the carbon microphone which produced a strong telephone signal. (from History of the telephone) -
RCA 630-TS, the first mass-produced television set, which sold in 1946–1947 (from History of television) -
Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation (from History of radio) -
"Doc" Herrold is shown at the microphone of KQW, early 1920s. (from History of broadcasting) -
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 "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 magazine advertisement announcing commercial launch of Picturephone service. (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. (from History of radio) -
Public television in France uses 819 line b&w high definition, from 1959 until 1983 (TF1). (from History of television) -
Typical low-cost webcam used with many personal computers (from History of videotelephony) -
Apple iPhone smartphone (from History of the telephone) -
1917 wall telephone, open to show magneto and local battery (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) -
Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio) -
Reginald Fessenden (around 1906) (from History of radio) -
First television test broadcast transmitted by the NHK Broadcasting Technology Research Institute in May 1939 (from History of television) -
Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. (from History of the telephone) -
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) -
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) -
Private conversation, 1910 (from History of the telephone) -
Reginald Fessenden, the "father" of radio broadcasting in the US (from History of broadcasting) -
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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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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) -
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) -
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) -
Caricature of Sir John Reith, by Wooding (from History of broadcasting) -
A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris (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) -
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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) -
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Charles Logwood broadcasting at station 2XG, New York City, circa November, 1916 (from History of broadcasting) -
Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves (from History of radio) -
The Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis (from History of television) -
An early Smart TV from 2012 running the discontinued Orsay platform (from History of television) -
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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Color bars used in a test pattern, sometimes used when no program material is available. (from History of television) -
Baird in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" (right). (from History of television) -
A 19th century acoustic tin can or "lovers' 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) -
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) -
Philo Farnsworth in 1924 (from History of television) -
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 first mass-produced Czechoslovak TV-set Tesla 4001A (1953–57) (from History of television) -
Antonio Meucci, 1854, constructed telephone-like devices. (from History of the telephone) -
The master telephone patent granted to Bell, 174465, March 10, 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) -
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) -
1896 Telephone (Sweden) (from History of the telephone) -
Top of cellular telephone tower (from History of the telephone) -
Swedish Prime Minister Tage Erlander using an Ericsson videophone to speak with Lennart Hyland, a popular TV show host (1969) (from History of videotelephony) -
Manfred von Ardenne in 1933 (from History of television) -
Artist's conception: 21st-century videotelephony imagined in the early 20th century (1910) (from History of videotelephony)
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Selected biography -
Antonio Santi Giuseppe Meucci (/meɪˈuːtʃi/ may-OO-chee, Italian: [anˈtɔːnjo meˈuttʃi]; 13 April 1808 – 18 October 1889) was an Italian inventor and an associate of Giuseppe Garibaldi, a major political figure in the history of Italy. Meucci is best known for developing a voice-communication apparatus that several sources credit as the first telephone.
Meucci set up a form of voice-communication link in his Staten Island, New York, home that connected the second-floor bedroom to his laboratory. He submitted a patent caveat for his telephonic device to the U.S. Patent Office in 1871, but there was no mention of electromagnetic transmission of vocal sound in his caveat. In 1876, Alexander Graham Bell was granted a patent for the electromagnetic transmission of vocal sound by undulatory electric current. Despite the longstanding general crediting of Bell with the accomplishment, the Italian Ministry of Cultural Heritage and Activities supported celebrations of Meucci's 200th birthday in 2008 using the title "Inventore del telefono" (Inventor of the telephone). The U.S. House of Representatives in a resolution in 2002 also acknowledged Meucci's work in the invention of the telephone, although the U.S. Senate did not join the resolution and the interpretation of the resolution is disputed. (Full article...)Did you know (auto-generated) -
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