A Gower telephone, at the Musée des Arts et Métiers in Paris
Telecommunication is the transmission of messages, over significant distances, for the purpose of communication. In earlier times, telecommunications involved the use of visual signals, such as smoke, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded drumbeats, lung-blown horns, or sent by loud whistles, for example.
In the modern age of electricity and electronics, telecommunications has typically involved the use of electric means such as the telegraph, the telephone, and the teletype, the use of microwave communications, the use of fiber optics and their associated electronics, and/or the use of the Internet. The first breakthrough into modern electrical telecommunications came with the development of the telegraph during the 1830s and 1840s. The use of these electrical means of communications exploded into use on all of the continents of the world during the 19th century, and these also connected the continents via cables on the floors of the ocean. These three systems of communications all required the use of conducting metal wires.
A revolution in wireless telecommunications began in the first decade of the 20th century, with Guglielmo Marconi winning the Nobel Prize in Physics in 1909 for his pioneering developments in wireless radio communications. Other early inventors and developers in the field of electrical and electronic telecommunications included Samuel F.B. Morse, Edwin Armstrong, Joseph Henry, and Lee de Forest (who invented the triode) of the United States, as well as John Logie Baird of Scotland, Nikola Tesla, an Serbian emigrant to the United States, and Alexander Graham Bell of Scotland, who lived in Canada, and then invented the telephone in the United States
Telecommunications play an important role in the world economy and the worldwide telecommunication industry's revenue was estimated to be $3.85 trillion in 2008. The service revenue of the global telecommunications industry was estimated to be $1.7 trillion in 2008, and is expected to touch $2.7 trillion by 2013.Contents [hide] 1 History
1.1 Early telecommunications
1.2 The telegraph and the telephone
1.3 Radio and television
1.4 Computer networks and the Internet
2 Key concepts
2.1 Basic elements
2.2 Analog or digital communications?
2.3 Communications networks
2.4 Communication channels
3 Society and telecommunication
3.1 Economic impact
3.2 Social impact
3.3 Other impacts
4 Telecommunication and government
5 Modern operation
5.2 Radio and television
5.3 The Internet
5.4 Local Area Networks and Wide Area Networks
6 Telecommunication by region
7 See also
9 Further reading
10 External links
A replica of one of Chappe's semaphore towers in Nalbach
During the Middle Ages, chains of beacons 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 the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London that signaled the arrival of the Spanish warships.
In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system (or semaphore line) between Lille and Paris. However semaphore systems suffered from the need for skilled operators and the expensive towers at intervals of ten to thirty kilometers (six to twenty miles). As a result of competition from the electrical telegraph, the last commercial semaphore line was abandoned in 1880.