Telecommunication 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. Telecommunication is often used in its plural form.
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 fiber, and communications satellites.
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).
According to Article 1.3 of the Radio Regulations (RR), telecommunication is defined as « Any transmission, emission or reception of signs, signals, writings, images and sounds or intelligence of any nature by wire, radio, optical, or other electromagnetic systems.» This definition is identical to those contained in the Annex to the Constitution and Convention of the International Telecommunication Union (Geneva, 1992).
The early telecommunication networks were created with copper wires as the physical medium for signal transmission. For many years, these networks were used for basic phone services, namely voice and telegrams. Since the mid-1990s, as the internet has grown in popularity, voice has been gradually supplanted by data. This soon demonstrated the limitations of copper in data transmission, prompting the development of optics.
Devon(/ˈdɛvən/, also known asDevonshire) is acountyofEngland, reaching from theBristol Channelin the north to theEnglish Channelin the south. It is part ofSouth West England, bounded byCornwallto the west,Somersetto the north-east andDorsetto the east. The city ofExeteris thecounty town. The county includes the districts ofEast Devon,Mid Devon,North Devon,South Hams,Teignbridge,TorridgeandWest Devon.PlymouthandTorbayare each geographically part of Devon, but are administered asunitary authorities.Combined as aceremonial county, Devon's area is 6,707 km2(2,590 square miles)and its population is about 1.1 million.
Devon derives its name fromDumnonia(the shift frommtovis a typicalCeltic consonant shift). During theBritish Iron Age,Roman Britainand theearly Middle Ages, this was the homeland of theDumnoniiBrittonicCelts. TheAnglo-Saxon settlement of Britainresulted in the partial assimilation of Dumnonia into theKingdom of Wessexduring the eighth and ninth centuries. The western boundary with Cornwall was set at theRiver TamarbyKing Æthelstanin 936. Devon was later constituted as ashireof theKingdom of England.
The north and south coasts of Devon each have both cliffs and sandy shores, and the county'sbayscontainseaside resorts,fishing townsandports. The inland terrain is rural, generally hilly and has a lower population density than many other parts of England.Dartmooris the largest open space in southern England, at 954 km2(368 square miles);itsmoorlandextends across a large expanse ofgranitebedrock. To the north of Dartmoor are theCulm MeasuresandExmoor. In the valleys and lowlands of south and east Devon the soil is more fertile, drained by rivers including theExe, theCulm, theTeign, theDartand theOtter.
As well as agriculture, much of theeconomy of Devonis based ontourism. The comparatively mild climate, coastline and landscape make Devon a destination forrecreation and leisure in England. Visitors are particularly attracted to the Dartmoor and Exmoornational parks; its coasts, including the resort towns along the south coast known collectively as theEnglish Riviera; theJurassic CoastandNorth Devon's UNESCO Biosphere Reserve; and the countryside including theCornwall and West Devon Mining Landscape.