Thehistory of telecommunication began with the use ofsmoke signals anddrums inAfrica,Asia, and theAmericas. In the 1790s, the first fixedsemaphore systems emerged inEurope. However, it was not until the 1830s that electricaltelecommunication systems started to appear. This article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. The history of telecommunication is an important part of the largerhistory of communication.
Early telecommunications includedsmoke signals anddrums.Talking drums were used by natives inAfrica, and smoke signals inNorth America andChina. These systems were often used to do more than announce the presence of a military camp.[1][2]
InRabbinical Judaism a signal was given by means of kerchiefs or flags at intervals along the way back to the high priest to indicate the goat "for Azazel" had been pushed from the cliff.
Homing pigeons have occasionally been used throughout history by different cultures.Pigeon post hadPersian roots, and was later used by the Romans to aid their military.[3]
Greekhydraulic semaphore systems were used as early as the 4th century BC. The hydraulic semaphores, which worked with water filled vessels and visual signals, functioned asoptical telegraphs. However, they could only utilize a very limited range of pre-determined messages, and as with all such optical telegraphs could only be deployed during good visibility conditions.[4]
During the Middle Ages, chains ofbeacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use was during theSpanish Armada, when a beacon chain relayed a signal fromPlymouth to London that signaled the arrival of the Spanish warships.[5]
In 1774, the Swiss physicist Georges Lesage built an electrostatic telegraph consisting of a set of 24 conductive wires a few meters long connected to 24 elder balls suspended from a silk thread (each wire corresponds to a letter). The electrification of a wire by means of an electrostatic generator causes the corresponding elder ball to deflect and designate a letter to the operator located at the end of the line. The sequence of selected letters leads to the writing and transmission of a message.[6]
French engineerClaude Chappe began working on visual telegraphy in 1790, using pairs of "clocks" whose hands pointed at different symbols. These did not prove quite viable at long distances, and Chappe revised his model to use two sets of jointed wooden beams. Operators moved the beams using cranks and wires.[7] He built his firsttelegraph line betweenLille andParis, followed by a line fromStrasbourg to Paris. In 1794, a Swedish engineer,Abraham Edelcrantz built a quite different system fromStockholm toDrottningholm. As opposed to Chappe's system which involved pulleys rotating beams of wood, Edelcrantz's system relied only upon shutters and was therefore faster.[8]
However, semaphore as a communication system suffered from the need for skilled operators and expensive towers often at intervals of only ten to thirty kilometers (six to nineteen miles). As a result, the last commercial line was abandoned in 1880.[9]
Experiments oncommunication with electricity, initially unsuccessful, started in about 1726. Scientists includingLaplace,Ampère, andGauss were involved.
An early experiment inelectrical telegraphy was an 'electrochemical' telegraph created by theGerman physician, anatomist and inventorSamuel Thomas von Sömmerring in 1809, based on an earlier, less robust design of 1804 by Spanishpolymath and scientistFrancisco Salva Campillo.[10] Both their designs employed multiple wires (up to 35) in order to visually represent almost all Latin letters and numerals. Thus, messages could be conveyed electrically up to a few kilometers (in von Sömmerring's design), with each of the telegraph receiver's wires immersed in a separate glass tube of acid. An electric current was sequentially applied by the sender through the various wires representing each digit of a message; at the recipient's end the currents electrolysed the acid in the tubes in sequence, releasing streams of hydrogen bubbles next to each associated letter or numeral. The telegraph receiver's operator would visually observe the bubbles and could then record the transmitted message, albeit at a very lowbaud rate.[10] The principal disadvantage to the system was its prohibitive cost, due to having to manufacture and string-up the multiple wire circuits it employed, as opposed to the single wire (with ground return) used by later telegraphs.
Thefirst working telegraph was built byFrancis Ronalds in 1816 and used static electricity.[11]
Charles Wheatstone andWilliam Fothergill Cooke patented a five-needle, six-wire system, which entered commercial use in 1838.[12] It used the deflection of needles to represent messages and started operating over twenty-one kilometres (thirteen miles) of theGreat Western Railway on 9 April 1839. Both Wheatstone and Cooke viewed their device as "an improvement to the [existing] electromagnetic telegraph" not as a new device.
On the other side of theAtlantic Ocean,Samuel Morse developed a version of the electrical telegraph which he demonstrated on 2 September 1837.Alfred Vail saw this demonstration and joined Morse to develop the register—a telegraph terminal that integrated a logging device for recording messages to paper tape. This was demonstrated successfully over three miles (five kilometres) on 6 January 1838 and eventually over forty miles (sixty-four kilometres) betweenWashington, D.C., andBaltimore on 24 May 1844. The patented invention proved lucrative and by 1851 telegraph lines in theUnited States spanned over 20,000 miles (32,000 kilometres).[13] Morse's most important technical contribution to this telegraph was the simple and highly efficientMorse Code, co-developed with Vail, which was an important advance over Wheatstone's more complicated and expensive system, and required just two wires. The communications efficiency of the Morse Code preceded that of theHuffman code indigital communications by over 100 years, but Morse and Vail developed the code purelyempirically, with shorter codes for more frequent letters.
Thesubmarine cable across theEnglish Channel, wire coated ingutta percha, was laid in 1851.[14] Transatlantic cables installed in 1857 and 1858 only operated for a few days or weeks (carried messages of greeting back and forth betweenJames Buchanan andQueen Victoria) before they failed.[15] The project to lay a replacement line was delayed for five years by theAmerican Civil War. The first successfultransatlantic telegraph cable was completed on 27 July 1866, allowing continuous transatlantic telecommunication for the first time.
The electric telephone was invented in the 1870s, based on earlier work withharmonic (multi-signal) telegraphs. The first commercial telephone services were set up in 1878 and 1879 on both sides of the Atlantic in the cities ofNew Haven,Connecticut in the US andLondon,England in theUK.Alexander Graham Bell held the master patent for the telephone that was needed for such services in both countries.[16] All other patents for electric telephone devices and features flowed from this master patent. Credit for the invention of the electric telephone has been frequently disputed, and new controversies over the issue have arisen from time-to-time. As with other great inventions such as radio, television, the light bulb, and thedigital computer, there were several inventors who did pioneering experimental work onvoice transmission over a wire, who then improved on each other's ideas. However, the key innovators were Alexander Graham Bell andGardiner Greene Hubbard, who created the first telephone company, theBell Telephone Company in the United States, which later evolved intoAmerican Telephone & Telegraph (AT&T), at times the world's largest phone company.
Telephone technology grew quickly after the first commercial services emerged, with inter-city lines being built andtelephone exchanges in every major city of the United States by the mid-1880s.[17][18][19] Thefirst transcontinental telephone call occurred on January 25, 1915. Despite this, transatlantic voice communication remained impossible for customers until January 7, 1927, when a connection was established using radio.[20] However no cable connection existed untilTAT-1 was inaugurated on September 25, 1956, providing 36 telephone circuits.[21]
In 1880, Bell and co-inventorCharles Sumner Tainter conducted the world's first wireless telephone call via modulated lightbeams projected byphotophones. The scientific principles of their invention would not be utilized for several decades, when they were first deployed in military andfiber-optic communications.
The first transatlantictelephone cable (which incorporated hundreds ofelectronic amplifiers) was not operational until 1956, only six years before the first commercial telecommunications satellite,Telstar, was launched into space.[22]
Over several years starting in 1894, the Italian inventorGuglielmo Marconi worked on adapting the newly discovered phenomenon ofradio waves to telecommunication, building the first wireless telegraphy system using them.[23] In December 1901, he established wireless communication betweenSt. John's, Newfoundland andPoldhu, Cornwall (England), earning him aNobel Prize in Physics (which he shared withKarl Braun) in 1909.[24] In 1900,Reginald Fessenden was able to wirelessly transmit a human voice.
Millimetre wave communication was first investigated byBengali physicistJagadish Chandra Bose during 1894–1896, when he reached anextremely high frequency of up to 60 GHz in his experiments.[25] He also introduced the use ofsemiconductor junctions to detect radio waves,[26] when hepatented theradiocrystal detector in 1901.[27][28]
In 1924,Japanese engineerKenjiro Takayanagi began a research program onelectronic television. In 1925, he demonstrated a cathode-ray tube (CRT) television with thermal electron emission.[29] In 1926, he demonstrated a CRT television with 40-lineresolution,[30] the first working example of a fullyelectronic television receiver.[29] In 1927, he increased the television resolution to 100 lines, which was unrivaled until 1931.[31] In 1928, he was the first to transmit human faces in half-tones on television, influencing the later work ofVladimir K. Zworykin.[32]
On March 25, 1925, Scottish inventorJohn Logie Baird publicly demonstrated thetransmission of moving silhouette pictures at the London department storeSelfridge's. Baird's system relied upon the fast-rotatingNipkow disk, and thus it became known as themechanical television. In October 1925, Baird was successful in obtaining moving pictures withhalftone shades, which were by most accounts the first true television pictures.[33] This led to a public demonstration of the improved device on 26 January 1926 again atSelfridges. His invention formed the basis of semi-experimental broadcasts done by theBritish Broadcasting Corporation beginning September 30, 1929.[34]
For most of the twentieth century televisions used thecathode-ray tube (CRT) invented byKarl Braun.Such a television was produced byPhilo Farnsworth, who demonstrated crude silhouette images to his family in Idaho on September 7, 1927.[35] Farnsworth's device would compete with the concurrent work ofKalman Tihanyi andVladimir Zworykin. Though the execution of the device was not yet what everyone hoped it could be, it earned Farnsworth a small production company. In 1934, he gave the first public demonstration of the television at Philadelphia's Franklin Institute and opened his own broadcasting station.[36] Zworykin's camera, based on Tihanyi's Radioskop, which later would be known as theIconoscope, had the backing of the influentialRadio Corporation of America (RCA). In the United States, court action between Farnsworth and RCA would resolve in Farnsworth's favour.[37]John Logie Baird switched from mechanical television and became a pioneer of colour television using cathode-ray tubes.[33]
After mid-century the spread of coaxial cable andmicrowave radio relay allowedtelevision networks to spread across even large countries.
The modern period of telecommunication history from 1950 onwards is referred to as thesemiconductor era, due to the wide adoption ofsemiconductor devices in telecommunication technology. The development oftransistor technology and thesemiconductor industry enabled significant advances in telecommunication technology, led to the price of telecommunications services declining significantly, and led to a transition away from state-ownednarrowbandcircuit-switched networks to privatebroadbandpacket-switched networks. In turn, this led to a significant increase in the total number of telephone subscribers, reaching nearly 1 billion users worldwide by the end of the 20th century.[38]
The development ofmetal–oxide–semiconductor (MOS)large-scale integration (LSI) technology,information theory andcellular networking led to the development of affordablemobile communications. There was a rapid growth of thetelecommunications industry towards the end of the 20th century, primarily due to the introduction ofdigital signal processing inwireless communications, driven by the development of low-cost,very large-scale integration (VLSI)RF CMOS (radio-frequencycomplementary MOS) technology.[39]
The development ofvideotelephony involved the historical development of several technologies which enabled the use oflive video in addition to voice telecommunications. The concept of videotelephony was first popularized in the late 1870s in both the United States and Europe, although the basic sciences to permit its very earliest trials would take nearly a half century to be discovered. This was first embodied in the device which came to be known as thevideo telephone, or videophone, and it evolved from intensive research and experimentation in several telecommunication fields, notablyelectrical telegraphy,telephony,radio, andtelevision.
The development of the crucial video technology first started in the latter half of the 1920s in the United Kingdom and the United States, spurred notably byJohn Logie Baird andAT&T's Bell Labs. This occurred in part, at least by AT&T, to serve as an adjunct supplementing the use of the telephone. A number of organizations believed that videotelephony would be superior to plain voice communications. However, video technology was to be deployed inanalogtelevision broadcasting long before it could become practical—or popular—for videophones.
Videotelephony developed in parallel with conventionalvoice telephone systems from the mid-to-late 20th century. Only in the late 20th century with the advent of powerfulvideo codecs andhigh-speed broadband did it become a practical technology for regular use. With the rapid improvements and popularity of the Internet, it became widespread through the use ofvideoconferencing andwebcams, which frequently utilizeInternet telephony, and in business, wheretelepresence technology has helped reduce the need to travel.
Practical digital videotelephony was only made possible with advances invideo compression, due to the impractically high bandwidth requirements ofuncompressed video. To achieveVideo Graphics Array (VGA) quality video (480p resolution and256 colors) with raw uncompressed video, it would require a bandwidth of over 92 Mbps.[40]
The first U.S. satellite to relay communications wasProject SCORE in 1958, which used a tape recorder tostore and forward voice messages. It was used to send a Christmas greeting to the world from U.S. PresidentDwight D. Eisenhower. In 1960NASA launched anEcho satellite; the 100-foot (30 m) aluminizedPET film balloon served as a passive reflector for radio communications.Courier 1B, built byPhilco, also launched in 1960, was the world's first active repeater satellite. Satellites these days are used for many applications such as GPS, television, internet and telephone.
Telstar was the first active, direct relay commercialcommunications satellite. Belonging toAT&T as part of a multi-national agreement between AT&T,Bell Telephone Laboratories, NASA, the BritishGeneral Post Office, and theFrench National PTT (Post Office) to develop satellite communications, it was launched by NASA fromCape Canaveral on July 10, 1962, the first privately sponsored space launch.Relay 1 was launched on December 13, 1962, and became the first satellite to broadcast across thePacific on November 22, 1963.[41]
The first and historically most important application for communication satellites was in intercontinentallong-distance telephony. The fixedPublic Switched Telephone Network relaystelephone calls fromland line telephones to anearth station, where they are then transmitted a receivingsatellite dish via ageostationary satellite in Earth orbit. Improvements insubmarine communications cables, through the use offiber-optics, caused some decline in the use of satellites for fixed telephony in the late 20th century, but they still exclusively service remote islands such asAscension Island,Saint Helena,Diego Garcia, andEaster Island, where no submarine cables are in service. There are also some continents and some regions of countries where landline telecommunications are rare to nonexistent, for exampleAntarctica, plus large regions ofAustralia,South America,Africa,Northern Canada,China,Russia andGreenland.
After commercial long-distance telephone service was established via communication satellites, a host of other commercial telecommunications were also adapted to similar satellites starting in 1979, includingmobile satellite phones,satellite radio,satellite television andsatellite Internet access. The earliest adaption for most such services occurred in the 1990s as the pricing for commercialsatellite transponder channels continued to drop significantly.
Realization and demonstration, on October 29, 2001, of the firstdigital cinema transmission bysatellite inEurope[42][43][44] of afeature film by Bernard Pauchon,[45] Alain Lorentz, Raymond Melwig[46] and Philippe Binant.[47]
On September 11, 1940,George Stibitz was able to transmit problems usingteletype to his Complex Number Calculator inNew York City and receive the computed results back atDartmouth College inNew Hampshire.[48] This configuration of a centralized computer ormainframe with remote dumb terminals remained popular throughout the 1950s. However, it was not until the 1960s that researchers started to investigatepacket switching a technology that would allow chunks of data to be sent to different computers without first passing through a centralized mainframe. A four-node network emerged on December 5, 1969, between theUniversity of California, Los Angeles, theStanford Research Institute, theUniversity of Utah and theUniversity of California, Santa Barbara. This network would becomeARPANET, which by 1981 would consist of 213 nodes.[49] In June 1973, the first non-US node was added to the network belonging toNorway's NORSAR project. This was shortly followed by a node in London.[50]
ARPANET's development centred on theRequest for Comments process and on April 7, 1969, RFC 1 was published. This process is important because ARPANET would eventually merge with other networks to form theInternet and many of the protocols the Internet relies upon today were specified through this process. The firstTransmission Control Protocol (TCP) specification,RFC 675 (Specification of Internet Transmission Control Program), was written by Vinton Cerf,Yogen Dalal, and Carl Sunshine, and published in December 1974. It coined the term "Internet" as a shorthand for internetworking.[51] In September 1981, RFC 791 introduced theInternet Protocol v4 (IPv4). This established theTCP/IP protocol, which much of the Internet relies upon today. TheUser Datagram Protocol (UDP), a more relaxed transport protocol that, unlike TCP, did not guarantee the orderly delivery of packets, was submitted on 28 August 1980 as RFC 768. An e-mail protocol,SMTP, was introduced in August 1982 by RFC 821 and [[HTTP|http://1.0[permanent dead link]]] a protocol that would make the hyperlinked Internet possible was introduced in May 1996 by RFC 1945.
However, not all important developments were made through the Request for Comments process. Two popular link protocols forlocal area networks (LANs) also appeared in the 1970s. A patent for theToken Ring protocol was filed by Olof Söderblom on October 29, 1974.[52] And a paper on theEthernet protocol was published byRobert Metcalfe andDavid Boggs in the July 1976 issue ofCommunications of the ACM.[53] The Ethernet protocol had been inspired by theALOHAnet protocol which had been developed byelectrical engineering researchers at theUniversity of Hawaii.
Internet access became widespread late in the century, using the old telephone and television networks.
MOS technology was initially overlooked by Bell because they did not find it practical for analog telephone applications.[54][55] MOS technology eventually became practical for telephone applications with the MOSmixed-signal integrated circuit, which combines analog anddigital signal processing on a single chip, developed by former Bell engineerDavid A. Hodges with Paul R. Gray atUC Berkeley in the early 1970s.[55] In 1974, Hodges and Gray worked with R.E. Suarez to develop MOSswitched capacitor (SC) circuit technology, which they used to develop thedigital-to-analog converter (DAC) chip, using MOSFETs andMOS capacitors for data conversion. This was followed by theanalog-to-digital converter (ADC) chip, developed by Gray and J. McCreary in 1975.[55]
MOS SC circuits led to the development of PCM codec-filter chips in the late 1970s.[55][56] Thesilicon-gateCMOS (complementary MOS) PCM codec-filter chip, developed by Hodges and W.C. Black in 1980,[55] has since been the industry standard for digital telephony.[55][56] By the 1990s,telecommunication networks such as thepublic switched telephone network (PSTN) had been largely digitized withvery-large-scale integration (VLSI) CMOS PCM codec-filters, widely used inelectronic switching systems fortelephone exchanges anddata transmission applications.[56]
Thewireless revolution began in the 1990s,[57][58][59] with the advent of digitalwireless networks leading to a social revolution, and a paradigm shift from wired towireless technology,[60] including the proliferation of commercial wireless technologies such ascell phones,mobile telephony,pagers, wirelesscomputer networks,[57]cellular networks, thewireless Internet, andlaptop andhandheld computers with wireless connections.[61] The wireless revolution has been driven by advances inradio frequency (RF) andmicrowave engineering,[57] and the transition from analog to digital RF technology.[60][61]
Advances inmetal–oxide–semiconductor field-effect transistor (MOSFET, or MOS transistor) technology, the key component of the RF technology that enables digital wireless networks, has been central to this revolution.[60]Hitachi developed the vertical power MOSFET in 1969, but it was not until Ragle perfected the concept in 1976 that the power MOSFET became practical.[62] In 1977 Hitachi announce a planar type of DMOS that was practical for audio power output stages.[63]RF CMOS (radio frequencyCMOS)integrated circuit technology was later developed byAsad Abidi atUCLA in the late 1980s.[64] By the 1990s, RF CMOS integrated circuits were widely adopted asRF circuits,[64] while discrete MOSFET (power MOSFET and LDMOS) devices were widely adopted asRF power amplifiers, which led to the development and proliferation of digital wireless networks.[60][65] Most of the essential elements of modern wireless networks are built from MOSFETs, includingbase station modules,routers,[65]telecommunication circuits,[66] andradio transceivers.[64]MOSFET scaling has led to rapidly increasing wirelessbandwidth, which has been doubling every 18 months (as noted byEdholm's law).[60]
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