Telecommunication systems are generally designed by telecommunication engineers which sprang from technological improvements in the telegraph industry in the late 19th century and the radio and the telephone industries in the early 20th century. Today, telecommunication is widespread and devices that assist the process, such as the television, radio and telephone, are common in many parts of the world. There are also many networks that connect these devices, including computer networks,
public switched telephone network (PSTN), radio networks, and television networks. Computer communication across the Internet is one of many examples of telecommunication. Telecommunication plays a vital role in the world economy, and the telecommunication industry's revenue has been placed at just under 3% of the gross world product.
Telegraph and telephone Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837. Soon after he was joined by
Alfred Vail who developed 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) between
Washington, D.C. and
Baltimore on 24 May 1844. The patented invention proved lucrative and by 1851 telegraph lines in the United States spanned over 20,000 miles (32,000 kilometres). The first successful
transatlantic telegraph cable was completed on 27 July 1866, allowing transatlantic telecommunication for the first time. Earlier transatlantic cables installed in 1857 and 1858 only operated for a few days or weeks before they failed. The international use of the telegraph has sometimes been dubbed the "
Victorian Internet". The first commercial telephone services were set up in 1878 and 1879 on both sides of the Atlantic in the cities of
New Haven and
London.
Alexander Graham Bell held the master patent for the telephone that was needed for such services in both countries. The technology grew quickly from this point, with inter-city lines being built and
telephone exchanges in every major city of the United States by the mid-1880s. Despite this, transatlantic voice communication remained impossible for customers until January 7, 1927, when a connection was established using radio. However no cable connection existed until
TAT-1 was inaugurated on September 25, 1956, providing 36 telephone circuits. In 1880, Bell and co-inventor
Charles Sumner Tainter conducted the world's first wireless telephone call via modulated lightbeams projected by
photophones. The scientific principles of their invention would not be utilized for several decades, when they were first deployed in military and
fiber-optic communications.
Radio and television crystal radio receiver Over several years starting in 1894, the Italian inventor
Guglielmo Marconi built the first complete, commercially successful wireless telegraphy system based on airborne electromagnetic waves (
radio transmission). In December 1901, he would go on to established wireless communication between Britain and Newfoundland, earning him the
Nobel Prize in physics in 1909 (which he shared with
Karl Braun). In 1900,
Reginald Fessenden was able to wirelessly transmit a human voice. On March 25, 1925, Scottish inventor
John Logie Baird publicly demonstrated the transmission of moving silhouette pictures at the London department store
Selfridges. In October 1925, Baird was successful in obtaining moving pictures with
halftone shades, which were by most accounts the first true television pictures. This led to a public demonstration of the improved device on 26 January 1926 again at
Selfridges. Baird's first devices relied upon the
Nipkow disk and thus became known as the
mechanical television. It formed the basis of semi-experimental broadcasts done by the
British Broadcasting Corporation beginning September 30, 1929.
Satellite The first U.S. satellite to relay communications was
Project SCORE in 1958, which used a tape recorder to
store and forward voice messages. It was used to send a Christmas greeting to the world from U.S. President
Dwight D. Eisenhower. In 1960
NASA launched an
Echo satellite; the aluminized
PET film balloon served as a passive reflector for radio communications.
Courier 1B, built by
Philco, also launched in 1960, was the world's first active repeater satellite. Satellites these days are used for many applications such as uses in GPS, television, internet and telephone uses.
Telstar was the first active, direct relay commercial
communications satellite. Belonging to
AT&T as part of a multi-national agreement between AT&T,
Bell Telephone Laboratories, NASA, the British
General Post Office, and the
French National PTT (Post Office) to develop satellite communications, it was launched by NASA from
Cape 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 the
Pacific on November 22, 1963. The first and historically most important application for communication satellites was in intercontinental
long distance telephony. The fixed
Public Switched Telephone Network relays
telephone calls from
land line telephones to an
earth station, where they are then transmitted a receiving
satellite dish via a
geostationary satellite in Earth orbit. Improvements in
submarine communications cables, through the use of
fiber-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 as
Ascension Island,
Saint Helena,
Diego Garcia, and
Easter 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 example
Antarctica, plus large regions of Australia, South America, Africa, Northern Canada, China, Russia and
Greenland. 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, including
mobile satellite phones,
satellite radio,
satellite television and
satellite Internet access. The earliest adaption for most such services occurred in the 1990s as the pricing for commercial
satellite transponder channels continued to drop significantly.
Computer networks and the Internet On 11 September 1940,
George Stibitz was able to transmit problems using
teleprinter to his Complex Number Calculator in New York and receive the computed results back at
Dartmouth College in
New Hampshire. This configuration of a centralized computer or
mainframe computer with remote "dumb terminals" remained popular throughout the 1950s and into the 1960s. However, it was not until the 1960s that researchers started to investigate
packet switching — a technology that allows chunks of data to be sent between different computers without first passing through a centralized mainframe. A four-node network emerged on 5 December 1969. This network soon became the
ARPANET, which by 1981 would consist of 213 nodes. ARPANET's development centered around the Request for Comment process and on 7 April 1969, RFC 1 was published. This process is important because ARPANET would eventually merge with other networks to form the Internet, and many of the
communication protocols that the Internet relies upon today were specified through the Request for Comment process. In September 1981, RFC 791 introduced the
Internet Protocol version 4 (IPv4) and RFC 793 introduced the
Transmission Control Protocol (TCP) — thus creating the TCP/IP protocol that much of the Internet relies upon today.
Optical fiber Optical fiber can be used as a medium for telecommunication and
computer networking because it is flexible and can be bundled into cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few
repeaters. In 1966
Charles K. Kao and
George Hockham proposed optical fibers at STC Laboratories (STL) at
Harlow, England, when they showed that the losses of 1000 dB/km in existing glass (compared to 5-10 dB/km in coaxial cable) was due to contaminants, which could potentially be removed. Optical fiber was successfully developed in 1970 by
Corning Glass Works, with attenuation low enough for communication purposes (about 20
dB/km), and at the same time GaAs (Gallium arsenide)
semiconductor lasers were developed that were compact and therefore suitable for transmitting light through fiber optic cables for long distances. After a period of research starting from 1975, the first commercial fiber-optic communications system was developed, which operated at a wavelength around 0.8 μm and used GaAs semiconductor lasers. This first-generation system operated at a bit rate of 45
Mbps with repeater spacing of up to 10 km. Soon on 22 April 1977, General Telephone and Electronics sent the first live telephone traffic through fiber optics at a 6 Mbit/s throughput in Long Beach, California. The first wide area network fibre optic cable system in the world seems to have been installed by Rediffusion in Hastings, East Sussex, UK in 1978. The cables were placed in ducting throughout the town, and had over 1000 subscribers. They were used at that time for the transmission of television channels, not available because of local reception problems. The first
transatlantic telephone cable to use optical fiber was
TAT-8, based on Desurvire optimized laser amplification technology. It went into operation in 1988. In the late 1990s through 2000, industry promoters, and research companies such as KMI, and RHK predicted massive increases in demand for communications bandwidth due to increased use of the
Internet, and commercialization of various bandwidth-intensive consumer services, such as
video on demand,
Internet Protocol data traffic was increasing exponentially, at a faster rate than integrated circuit complexity had increased under
Moore's Law. ==Concepts==