Portal:Telecommunication

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The Telecommunication Portal

Earth station at the satellite communication facility Raisting Earth Station in Raisting, Bavaria, Germany

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 and pneumatic tube communication systems) 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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ISDN telephone

Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking systems with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance.

Prior to ISDN, the telephone system consisted of digital links like T1/E1 on the long-distance lines between telephone company offices and analog signals on copper telephone wires to the customers, the "last mile". At the time, the network was viewed as a way to transport voice, with some special services available for data using additional equipment like modems or by providing a T1 on the customer's location. What became ISDN started as an effort to digitize the last mile, originally under the name "Public Switched Digital Capacity" (PSDC). This would allow call routing to be completed in an all-digital system, while also offering a separate data line. The Basic Rate Interface, or BRI, is the standard last-mile connection in the ISDN system, offering two 64 kbit/s "bearer" lines and a single 16 kbit/s "delta" channel for commands and data. (Full article...)
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Bell c. 1917

Alexander Graham Bell (/ˈɡr.əm/, born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born Canadian-American inventor, scientist and engineer who is credited with patenting the first practical telephone. He also co-founded the American Telephone and Telegraph Company (AT&T) in 1885.

Bell's father, grandfather, and brother had all been associated with work on elocution and speech, and both his mother and wife were deaf; profoundly influencing Bell's life's work. His research on hearing and speech further led him to experiment with hearing devices which eventually culminated in Bell being awarded the first U.S. patent for the telephone, on March 7, 1876. Bell considered his invention an intrusion on his real work as a scientist and refused to have a telephone in his study. (Full article...)

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  • ... that Valley Public Television once raffled off a 1961 Rolls-Royce Silver Cloud, according to the wishes of the man who bequeathed it to the station?
  • ... that the 1988 closure of WLEE, once one of the top radio stations in Richmond, Virginia, also took WBBL, a church station in existence for nearly 65 years, off the air for good?
  • ... that when her boss told her to quit her unpaid television commenting role, Katie Phang quit her paid job instead?
  • ... that Massachusetts radio station WAAF pulled off an "unprecedented radio concert promotion coup" by organizing a concert by the Rolling Stones for 300 locals?
  • ... that West Virginia radio station WHIS made the first broadcast of a murder trial in the United States—and was broadcasting when the first on-air death occurred?
  • ... that San Francisco's "KYOU Radio" was the first terrestrial radio station to broadcast a program format consisting of podcasts?

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