The Telecommunication Portal

Earth station at the satellite communication facility 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) 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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Cathode-ray tube using electromagnetic focus and deflection. Parts shown are not to scale.

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...)
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Dr Ronald Hugh Barker
Ronald Hugh Barker FIEE (1915 – 7 October 2015) was an Irish physicist and the inventor of Barker code, a method for synchronising digital communication systems and framing received data using digital codes. The method was initially researched at the Signals Research and Development Establishment (SRDE) just after World War II, and was intended for use in radar, rocket telemetry and digital speech. In 1952, Barker found seven Barker sequences up to a length of 13 useful for correlation.[clarify] These sequences are widely used in most data transmissions today. Examples of applications include radar, mobile phone technology, telemetry, digital speech, ultrasound imaging and testing, GPS and Wi-Fi. (Full article...)

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