The Telecommunication Portal
Telecommunication, often used in its plural form, is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field.
The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions.
Other examples of pre-modern long-distance communication included audio messages, such as coded drumbeats, lung-blown horns, and loud whistles. 20th- and 21st-century technologies for long-distance communication usually involve electrical and electromagnetic technologies, such as telegraph, telephone, television and teleprinter, networks, radio, microwave transmission, optical fibre, and communications satellites.
The early telecommunication networks were created with metallic wires as the physical medium for signal transmission. For many years, these networks were used for telegraph and voice services. A revolution in wireless communication began in the first decade of the 20th century with the pioneering developments in radio communications by Guglielmo Marconi, who won the Nobel Prize in Physics in 1909, and other notable pioneering inventors and developers in the field of electrical and electronic telecommunications. These included Charles Wheatstone and Samuel Morse (inventors of the telegraph), Antonio Meucci and Alexander Graham Bell (some of the inventors and developers of the telephone, see Invention of the telephone), Edwin Armstrong and Lee de Forest (inventors of radio), as well as Vladimir K. Zworykin, John Logie Baird and Philo Farnsworth (some of the inventors of television).
With the proliferation of digital technologies since the 1960s, voice communication has been gradually supplemented by data. The limitations of metallic data transmission prompted the development of optics. The development of media-independent Internet technologies provided access to world-wide services for individual users without limitations to location or time. (Full article...)
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A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons.
In CRT television sets and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference. In modern CRT monitors and televisions the beams are bent by magnetic deflection, using a deflection yoke. Electrostatic deflection is commonly used in oscilloscopes. (Full article...)General images
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Swedish Prime Minister Tage Erlander using an Ericsson videophone to speak with Lennart Hyland, a popular TV show host (1969) (from History of videotelephony)
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The master telephone patent, 174465, granted to Bell, March 7, 1876 (from History of telecommunication)
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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)
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Typical low-cost webcam used with many personal computers (from History of videotelephony)
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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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A replica of one of Claude Chappe's semaphore towers (optical telegraph) in Nalbach, Germany (from History of telecommunication)
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1896 Telephone (Sweden) (from History of the telephone)
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Actor portraying Alexander Graham Bell in a 1926 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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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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Historical marker commemorating the first telephone central office in New York State (1878) (from History of the telephone)
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Reginald Fessenden (around 1906) (from History of radio)
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Manfred von Ardenne in 1933 (from History of television)
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Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. (from History of the telephone)
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A German rotary dial telephone, the W48 (from History of the telephone)
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Broadcasting pioneer Frank Conrad in a 1921 portrait (from History of broadcasting)
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Reginald Fessenden, the "father" of radio broadcasting in the US (from History of broadcasting)
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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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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)
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RCA 630-TS, the first mass-produced television set, which sold in 1946–1947 (from History of television)
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The 1969 AT&T Mod II Picturephone, the result of decades long R&D at a cost of over $500M. (from History of telecommunication)
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Family watching TV, 1958 (from History of television)
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Caricature of Sir John Reith, by Wooding (from History of broadcasting)
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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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Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. (from History of the telephone)
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Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation (from History of radio)
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1917 wall telephone, open to show magneto and local battery (from History of the telephone)
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Tivadar Puskás proposed the telephone switchboard exchange in 1876. (from History of the telephone)
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Lee DeForest broadcasting Columbia phonograph records on pioneering New York station 2XG, in 1916 (from History of broadcasting)
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Right side view, housing removed, one of its printed circuit boards exposed (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)
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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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Guglielmo Marconi (from History of broadcasting)
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Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia) (from History of telecommunication)
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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)
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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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Ad for the beginning of experimental television broadcasting in New York City by RCA in 1939 (from History of television)
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The master telephone patent granted to Bell, 174465, March 10, 1876 (from History of the telephone)
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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)
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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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Modern Apple iPhone. This phone is considered a smartphone (from History of the telephone)
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Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
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Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves (from History of radio)
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A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris (from History of the telephone)
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Baird in 1925 with his televisor equipment and dummies "James" and "Stooky Bill" (right). (from History of television)
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Bell prototype telephone stamp(from History of the telephone)
Centennial Issue of 1976 -
A 19th century acoustic tin can or "lovers' telephone" (from History of the telephone)
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DBS satellite dishes. (from History of television)
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British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio)
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The Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis (from History of television)
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Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897 (from History of radio)
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Artist's conception: 21st-century videotelephony imagined in the early 20th century (1910) (from History of videotelephony)
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The French Matra videophone (1970) (from History of videotelephony)
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Top of cellular telephone tower (from History of the telephone)
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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)
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Thomas Edison invented the carbon microphone which produced a strong telephone signal. (from History of the telephone)
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Naomi ("Joan") Melwit and Norman Banks at the 3KZ microphone, in the late 1930s (from History of broadcasting)
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"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)
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"Doc" Herrold is shown at the microphone of KQW, early 1920s. (from History of broadcasting)
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Stock telegraph ticker machine by Thomas Edison (from History of telecommunication)
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Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876. (from History of the telephone)
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Private conversation, 1910 (from History of the telephone)
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Color bars used in a test pattern, sometimes used when no program material is available. (from History of television)
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Charles Logwood broadcasting at station 2XG, New York City, circa November, 1916 (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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Philo Farnsworth in 1924 (from History of television)
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The Australian Broadcasting Corporation logo, first introduced in 1975 and based on the Lissajous curve (from History of broadcasting)
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Antonio Meucci, 1854, constructed telephone-like devices. (from History of the telephone)
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An early Smart TV from 2012 running the discontinued Orsay platform (from History of television)
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Old Receiver schematic, c.1906 (from History of the telephone)
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The first mass-produced Czechoslovak TV-set Tesla 4001A (1953–57) (from History of television)
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Antonio Meucci's telephone. (from History of the telephone)
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