History of telecommunication facts for kids

A model of one of Claude Chappe's semaphore towers (optical telegraph) in Nalbach, Germany

The history of telecommunication is all about how people have sent messages over long distances throughout time. It started with simple things like smoke signals and drums in places like Africa, Asia, and the Americas. In the 1790s, the first fixed semaphore systems appeared in Europe. But the real change happened in the 1830s when electrical telecommunication systems began. This article explores the story of telecommunication and the amazing people who helped create the systems we use today.

Early Ways to Send Messages
The Electric Telegraph
The Telephone
Radio and Television
The Semiconductor Era
Timeline of Telecommunication Milestones
See Also

Early Ways to Send Messages

Early forms of telecommunication included smoke signals and drums. Talking drums were used by native people in Africa. Smoke signals were common in North America and China. These systems often did more than just announce a military camp.

Homing pigeons were also used to carry messages. This "pigeon post" started in Persia and was later used by the Romans for their military.

The ancient Greeks used hydraulic semaphore systems as early as the 4th century BC. These worked with water-filled containers and visual signals. They were like early optical telegraphs. However, they could only send a few pre-set messages. Also, they only worked when the weather was clear.

Code of letters and symbols for Chappe telegraph (Rees's Cyclopaedia)

During the Middle Ages, people used chains of beacons on hilltops to relay signals. These beacon chains could only send one piece of information, like "the enemy has been seen." The meaning had to be decided beforehand. A famous example was during the Spanish Armada. A chain of beacons sent a signal from Plymouth to London, announcing the arrival of the Spanish warships.

In 1774, a Swiss scientist named Georges Lesage built an electrostatic telegraph. It had 24 wires connected to small balls. When a wire was charged with electricity, its ball would move, pointing to a letter. This allowed messages to be sent letter by letter.

French engineer Claude Chappe started working on visual telegraphy in 1790. He first used "clocks" with hands pointing to symbols. These didn't work well over long distances. So, Chappe changed his design to use two sets of jointed wooden beams. Operators moved these beams with cranks and wires. He built his first telegraph line between Lille and Paris. Then came a line from Strasbourg to Paris. In 1794, a Swedish engineer, Abraham Edelcrantz, built a different system in Sweden. Chappe's system used pulleys to rotate wooden beams. Edelcrantz's system used shutters, which made it faster.

However, semaphore systems needed skilled operators and expensive towers every 10 to 30 kilometers (6 to 19 miles). Because of this, the last commercial semaphore line closed in 1880.

The Electric Telegraph

Experiments with sending messages using electricity began around 1726. Scientists like Laplace, Ampère, and Gauss were involved.

One early electric telegraph was made by the German scientist Samuel Thomas von Sömmerring in 1809. It used many wires (up to 35). Each wire was in a glass tube of acid. When electricity flowed through a wire, it made hydrogen bubbles appear next to a letter or number. The operator would then read the message. This system was very expensive because it needed so many wires. Later telegraphs used only one wire.

The first working telegraph was built by Francis Ronalds in 1816. It used static electricity.

Charles Wheatstone and William Fothergill Cooke patented a system in 1838. It used five needles and six wires. The needles would move to show messages. It started working on April 9, 1839, along 21 kilometers (13 miles) of the Great Western Railway.

Stock telegraph ticker machine by Thomas Edison

Across the Atlantic Ocean, Samuel Morse developed his own electric telegraph. He showed it on September 2, 1837. Alfred Vail joined Morse and helped create a device that recorded messages onto paper tape. This was successfully shown over 5 kilometers (3 miles) on January 6, 1838. Later, it worked over 64 kilometers (40 miles) between Washington, D.C. and Baltimore on May 24, 1844. Morse's invention made a lot of money. By 1851, telegraph lines in the United States stretched over 32,000 kilometers (20,000 miles). Morse's most important contribution was the simple and efficient Morse Code. He developed it with Vail. It was much better than Wheatstone's system and only needed two wires. Morse Code used shorter codes for letters that were used more often.

The first submarine cable was laid across the English Channel in 1851. It was a wire covered in gutta percha. Cables were also laid across the Atlantic in 1857 and 1858. They only worked for a few days or weeks, sending greetings between James Buchanan and Queen Victoria. The project to lay a new line was delayed for five years by the American Civil War. The first successful transatlantic telegraph cable was finished on July 27, 1866. This allowed continuous communication across the Atlantic for the first time.

The Telephone

The master telephone patent, 174465, granted to Bell, March 7, 1876

The electric telephone was invented in the 1870s. It was based on earlier work with sending multiple signals over a wire. The first commercial telephone services started in 1878 and 1879. They were in New Haven, Connecticut in the US, and London, England in the UK. Alexander Graham Bell held the main patent for the telephone. All other patents for telephone devices came from his. Many people have argued about who truly invented the electric telephone. Like other big inventions such as radio or television, several inventors worked on sending voice over a wire. They improved on each other's ideas. However, the main people were Alexander Graham Bell and Gardiner Greene Hubbard. They started the first telephone company, the Bell Telephone Company, in the United States. This company later became American Telephone & Telegraph (AT&T), which was once the world's largest phone company.

Telephone technology grew quickly. Inter-city lines were built, and telephone exchanges appeared in every major US city by the mid-1880s. The first transcontinental telephone call happened on January 25, 1915. But talking across the Atlantic was not possible for customers until January 7, 1927. This connection used radio. A cable connection didn't exist until TAT-1 opened on September 25, 1956. It provided 36 telephone lines.

In 1880, Bell and Charles Sumner Tainter made the world's first wireless telephone call. They used light beams from devices called photophones. The science behind their invention wasn't used for many decades. It later became important for military and fiber-optic communications.

The first transatlantic telephone cable, which had hundreds of electronic amplifiers, didn't work until 1956. This was only six years before the first commercial telecommunications satellite, Telstar, was launched into space.

Radio and Television

Starting in 1894, Italian inventor Guglielmo Marconi worked on using radio waves for telecommunication. He built the first wireless telegraphy system using them. In December 1901, he made wireless communication between St. John's, Newfoundland and Poldhu, Cornwall (England). He won a Nobel Prize in Physics in 1909, sharing it with Karl Braun. In 1900, Reginald Fessenden was able to send a human voice wirelessly.

Millimetre wave communication was first studied by Bengali physicist Jagadish Chandra Bose between 1894 and 1896. He reached very high frequencies in his experiments. He also used semiconductor parts to detect radio waves. He patented the radio crystal detector in 1901.

In 1924, Japanese engineer Kenjiro Takayanagi began researching electronic television. In 1925, he showed a CRT television. In 1926, he showed a CRT television with 40 lines of resolution. This was the first working fully electronic television receiver. In 1927, he made the resolution 100 lines, which was the best until 1931. In 1928, he was the first to show human faces on television using shades of gray.

On March 25, 1925, Scottish inventor John Logie Baird publicly showed moving silhouette pictures. He did this at the Selfridge's department store in London. Baird's system used a fast-spinning Nipkow disk, so it was called a mechanical television. In October 1925, Baird successfully got moving pictures with shades of gray. These are considered the first true television pictures. He showed his improved device again on January 26, 1926, at Selfridges. His invention was used for early broadcasts by the British Broadcasting Corporation starting September 30, 1929.

For most of the 20th century, televisions used the cathode ray tube (CRT) invented by Karl Braun. Such a television was produced by Philo Farnsworth. He showed simple silhouette images to his family in Idaho on September 7, 1927. Farnsworth's device competed with work by Kalman Tihanyi and Vladimir Zworykin. Farnsworth's device earned him a small production company. In 1934, he gave the first public demonstration of television at Philadelphia's Franklin Institute. He also opened his own broadcasting station. Zworykin's camera, based on Tihanyi's Radioskop (later called the Iconoscope), had the support of the powerful Radio Corporation of America (RCA). In the United States, a court case between Farnsworth and RCA ended with Farnsworth winning. John Logie Baird later switched from mechanical television and became a pioneer of color television using cathode-ray tubes.

After the mid-20th century, coaxial cable and microwave radio relay helped television networks spread across even large countries.

The Semiconductor Era

The modern period of telecommunication history, from 1950 onwards, is called the semiconductor era. This is because semiconductor devices were widely used in telecommunication technology. The development of transistor technology and the semiconductor industry led to big advances. The price of telecommunications services dropped a lot. There was a shift from state-owned narrowband networks to private broadband networks. This led to a huge increase in telephone users, reaching almost 1 billion worldwide by the end of the 20th century.

The development of metal–oxide–semiconductor (MOS) large-scale integration (LSI) technology, information theory, and cellular networks made affordable mobile communications possible. The telecommunications industry grew rapidly at the end of the 20th century. This was mainly due to digital signal processing in wireless communications. This was helped by the development of low-cost, very large-scale integration (VLSI) RF CMOS (radio-frequency complementary MOS) technology.

Video Calls

The 1969 AT&T Mod II Picturephone, which cost over $500M to develop.

The idea of videotelephony (video calls) became popular in the late 1870s. However, the science needed for early trials took almost 50 years to discover. The first device was called the video telephone. It came from a lot of research in areas like electrical telegraphy, telephony, radio, and television.

The key video technology started in the late 1920s in the UK and the US. John Logie Baird and AT&T's Bell Labs were important here. AT&T saw video calls as a way to improve telephone use. Many organizations thought video calls would be better than just voice calls. However, video technology was first used in analog television broadcasting long before it became practical for videophones.

Video calls developed alongside regular voice telephone systems from the mid to late 20th century. Only in the late 20th century, with powerful video codecs and high-speed broadband, did it become practical for everyday use. With the fast improvements and popularity of the Internet, video calls became common through videoconferencing and webcams. These often use Internet telephony. In business, telepresence technology has helped reduce the need for travel.

Practical digital video calls were only possible with advances in video compression. This is because uncompressed video needs a huge amount of internet speed. For example, a basic video quality (480p resolution) would need over 92 Mbps without compression.

Satellites in Space

The first US satellite to relay communications was Project SCORE in 1958. It used a tape recorder to store and forward voice messages. It sent a Christmas greeting to the world from US President Dwight D. Eisenhower. In 1960, NASA launched an Echo satellite. This 30-meter (100 ft) balloon acted as a passive reflector for radio communications. Courier 1B, also launched in 1960, was the world's first active repeater satellite. Today, satellites are used for many things like GPS, television, internet, and telephone.

Telstar was the first active, direct relay commercial communications satellite. It belonged to AT&T. It was part of an agreement between AT&T, Bell Telephone Laboratories, NASA, the British General Post Office, and the French National PTT to develop satellite communications. NASA launched it from Cape Canaveral on July 10, 1962. This was the first space launch sponsored by a private company. Relay 1 was launched on December 13, 1962. It became the first satellite to broadcast across the Pacific on November 22, 1963.

The most important early use for communication satellites was for long-distance phone calls between continents. The regular Public Switched Telephone Network sends telephone calls from land line phones to an earth station. From there, they are sent to a receiving satellite dish via a geostationary satellite in Earth orbit. Improvements in submarine communications cables, using fiber-optics, caused satellites to be used less for fixed phone calls in the late 20th century. However, they still serve remote islands like Ascension Island and Easter Island, where no submarine cables exist. Also, large parts of continents like Antarctica, Australia, South America, Africa, Northern Canada, China, Russia, and Greenland rely on satellites.

After commercial long-distance phone service started using satellites, many other commercial telecommunications also adapted to them. This began in 1979 and included mobile satellite phones, satellite radio, satellite television, and satellite Internet access. Most of these services started in the 1990s as the price for commercial satellite transponder channels dropped a lot.

On October 29, 2001, the first digital cinema transmission by satellite in Europe happened. It was a feature film shown by Bernard Pauchon and his team.

Computer Networks and the Internet

On September 11, 1940, George Stibitz was able to send math problems using a teletype to his Complex Number Calculator in New York City. He then received the answers back at Dartmouth College in New Hampshire. This setup, with a main computer and remote terminals, was popular throughout the 1950s. However, in the 1960s, researchers started looking into packet switching. This technology allowed chunks of data to be sent to different computers without first going through a central main computer. A four-node network appeared on December 5, 1969. It connected the University of California, Los Angeles, the Stanford Research Institute, the University of Utah, and the University of California, Santa Barbara. This network became ARPANET. By 1981, it had 213 nodes. In June 1973, the first non-US node was added in Norway. Soon after, a node was added in London.

ARPANET's development focused on the Request for Comments (RFC) process. On April 7, 1969, RFC 1 was published. This process was important because ARPANET eventually joined with other networks to form the Internet. Many of the rules the Internet uses today were created through this process. The first Transmission Control Protocol (TCP) rules were written by Vinton Cerf, Yogen Dalal, and Carl Sunshine. They were published in December 1974. This is where the term "Internet" came from. In September 1981, RFC 791 introduced the Internet Protocol v4 (IPv4). This created the TCP/IP protocol, which much of the Internet still uses today. The User Datagram Protocol (UDP), a simpler way to send data that doesn't guarantee orderly delivery, was submitted on August 28, 1980. An e-mail protocol, SMTP, was introduced in August 1982. HTTP, the protocol that made the hyperlinked Internet possible, was introduced in May 1996.

Not all important developments happened through the RFC process. Two popular link protocols for local area networks (LANs) also appeared in the 1970s. A patent for the Token Ring protocol was filed by Olof Söderblom on October 29, 1974. A paper on the Ethernet protocol was published by Robert Metcalfe and David Boggs in July 1976. The Ethernet protocol was inspired by the ALOHAnet protocol developed at the University of Hawaii.

Internet access became widespread late in the century. It used the existing telephone and television networks.

Digital Telephone Technology

MOS technology was first overlooked by Bell because they didn't think it was practical for analog phones. But it became useful for phones with the MOS mixed-signal integrated circuit. This chip combines analog and digital signal processing on one chip. It was developed by former Bell engineer David A. Hodges with Paul R. Gray in the early 1970s. In 1974, Hodges and Gray worked with R.E. Suarez to develop MOS switched capacitor (SC) circuit technology. They used this to create the digital-to-analog converter (DAC) chip, using MOSFETs and MOS capacitors for data conversion. This was followed by the analog-to-digital converter (ADC) chip, developed by Gray and J. McCreary in 1975.

MOS SC circuits led to the development of PCM codec-filter chips in the late 1970s. The silicon-gate CMOS (complementary MOS) PCM codec-filter chip, developed by Hodges and W.C. Black in 1980, has been the industry standard for digital telephony ever since. By the 1990s, telecommunication networks like the public switched telephone network (PSTN) were mostly digital. They used very-large-scale integration (VLSI) CMOS PCM codec-filters widely in electronic switching systems for telephone exchanges and data transmission applications.

The Wireless Revolution

The wireless revolution began in the 1990s. Digital wireless networks led to a big social change. People started moving from wired to wireless technology. This included the spread of cell phones, mobile telephony, pagers, wireless computer networks, cellular networks, the wireless Internet, and laptop and handheld computers with wireless connections. The wireless revolution was driven by advances in radio frequency (RF) and microwave engineering. It also involved the change from analog to digital RF technology.

Advances in metal–oxide–semiconductor field-effect transistor (MOSFET, or MOS transistor) technology were central to this revolution. MOSFETs are key parts of the RF technology that makes digital wireless networks possible. Hitachi developed the vertical power MOSFET in 1969. But it wasn't until 1976 that the power MOSFET became practical. In 1977, Hitachi announced a planar type of DMOS that was useful for audio power output stages. RF CMOS (radio frequency CMOS) integrated circuit technology was later developed by Asad Abidi at UCLA in the late 1980s. By the 1990s, RF CMOS integrated circuits were widely used as RF circuits. Separate MOSFET devices were widely used as RF power amplifiers. This led to the development and spread of digital wireless networks. Most parts of modern wireless networks are built from MOSFETs. This includes base station modules, routers, telecommunication circuits, and radio transceivers. MOSFET scaling has led to rapidly increasing wireless bandwidth, which has been doubling every 18 months (as noted by Edholm's law).

Timeline of Telecommunication Milestones

Early Non-Electrical Methods

Prehistoric times: Fires, beacons, smoke signals, communication drums, horns.
6th century BCE: Mail systems.
5th century BCE: Pigeon post begins.
4th century BCE: Hydraulic semaphores used in Greece.
15th century CE: Maritime flag semaphores for ships.
1672: First experimental acoustic (mechanical) telephone.
1790: Semaphore lines (optical telegraphs) are developed.
1867: Signal lamps are introduced.
1877: Acoustic phonograph is invented.
1900: Early optical picture transmission.

Basic Electrical Signals

1838: Electrical telegraph systems begin.
1830s: Attempts to develop "wireless telegraphy" start.
1858: First trans-Atlantic telegraph cable is laid.
1876: The Telephone is invented.
1880: Telephony via lightbeam photophones demonstrated.

Advanced Electrical and Electronic Signals

1896: First practical wireless telegraphy systems based on Radio.
1900: First television displayed only black and white images.
1914: First North American transcontinental telephone calling.
1927: Television is publicly demonstrated.
1927: First commercial radio-telephone service between U.K. and U.S.
1930: First experimental videophones.
1934: First commercial radio-telephone service between U.S. and Japan.
1936: World's first public videophone network.
1946: Limited capacity Mobile Telephone Service for cars.
1947: First working transistor.
1950: The Semiconductor era begins.
1956: Transatlantic telephone cable is operational.
1962: Commercial telecommunications satellite is launched.
1964: Fiber optical telecommunications begin.
1965: First North American public videophone network.
1969: Computer networking starts.
1973: First modern-era mobile (cellular) phone.
1974: The Internet begins to form.
1979: INMARSAT ship-to-shore satellite communications.
1981: First mobile (cellular) phone network.
1982: SMTP email is introduced.
1998: Mobile satellite hand-held phones become available.
2003: VoIP Internet Telephony becomes widespread.