Telecommunications

• 1. Introduction

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  In 1849, Paul Julius Reuter launched a pigeon service to fly stock prices between Aachen and Brussels. It ran for a year, lasting only until a gap in the telegraph link was finally closed. The birds were a stopgap, and the wires were the future. This is the story of telecommunication, the transmission of information over a distance by electrical or electronic means. The word itself was coined in 1904 by a French engineer and novelist named Edouard Estaunie, who called it the remote transmission of thought through electricity. How did humanity move from beacon fires that could carry a single bit of meaning to a global network moving exabytes of information every year? Why is a vacuum tube heated to glowing as central to this story as a transatlantic cable sunk to the ocean floor? And what does it mean that slow methods like postal mail and pneumatic tubes are deliberately shut out of the definition?

• 2. Before The Wires

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  Homing pigeons carried messages across cultures for centuries, with the practice rooted in Persia before the Romans adopted it for their military. Frontinus claimed Julius Caesar used pigeons as messengers during his conquest of Gaul. The Greeks sent the names of Olympic victors to distant cities the same way, and in the early 19th century the Dutch government ran the system across Java and Sumatra. Beacon chains on hilltops were the medieval answer to long distance, but they carried a single bit of information. The meaning of a signal, such as the enemy has been sighted, had to be agreed upon in advance, and one such chain relayed a warning from Plymouth to London during the Spanish Armada. In 1792, the French engineer Claude Chappe built the first fixed visual telegraphy system, a semaphore line running between Lille and Paris. Semaphore demanded skilled operators and costly towers spaced every ten to thirty kilometres. Competition from the electrical telegraph eventually killed it, and the last commercial line was abandoned in 1880.

• 3. Taming The Current

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  On the 25th of July 1837, the first commercial electrical telegraph was demonstrated by Sir William Fothergill Cooke and Sir Charles Wheatstone. Both men saw their device modestly, as an improvement to the existing electromagnetic telegraph rather than a new invention. Samuel Morse independently built his own version, demonstrated without success on the 2nd of September 1837, but his code marked an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was completed on the 27th of July 1866, allowing telecommunication across the ocean for the first time. After early efforts at a talking telegraph by Antonio Meucci and a telefon by Johann Philipp Reis, Alexander Bell filed a patent for the conventional telephone in February 1876. He beat Elisha Gray, who filed a caveat for a similar device, by only a few hours. The Bell Telephone Company set up the first commercial telephone services in 1878 and 1879, on both sides of the Atlantic in New Haven and London.

• 4. Signals Through The Air

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  In 1894, the Italian inventor Guglielmo Marconi began working with the newly discovered phenomenon of radio waves. By 1901 he had shown they could cross the Atlantic Ocean, and on the 17th of December 1902 a transmission from his station in Glace Bay, Nova Scotia became the world's first radio message to cross the Atlantic from North America. Marconi later won the 1909 Nobel Prize in Physics. By 1904 a commercial service transmitted nightly news summaries to subscribing ships, which folded them into their onboard newspapers. World War I and then World War II both accelerated radio for military use, from aircraft and land communication to radio navigation and radar. On the 25th of March 1925, John Logie Baird demonstrated moving pictures at the London department store Selfridges. His device relied on the Nipkow disk invented by Paul Nipkow, earning it the name mechanical television. It became the basis for experimental broadcasts the British Broadcasting Corporation began on the 30th of September 1929.

• 5. The Glowing Heart

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  The diode, the simplest vacuum tube, was invented in 1904 by John Ambrose Fleming, holding only a heated electron-emitting cathode and an anode. Electrons could flow in just one direction, from cathode to anode, and adding control grids let a small voltage govern the larger current. These tubes used thermionic emission for fundamental jobs like amplifying signals and rectifying current. They became key components of electronic circuits for the first half of the 20th century. Vacuum tubes were crucial to radio, television, radar, sound recording, long-distance telephone networks, and both analogue and early digital computers. It was the thermionic vacuum tube that made these technologies practical and widespread, creating the field of electronics itself. The cathode ray tube, invented by Karl Ferdinand Braun, powered televisions for most of the century. The first promising version came from Philo Farnsworth, who demonstrated it to his family on the 7th of September 1927. In the 1940s, semiconductor devices arrived, smaller and cheaper and more durable, and from the mid-1960s the transistor replaced the tube.

• 6. Switching The Message

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  On the 11th of September 1940, George Stibitz sent problems for his Complex Number Calculator from New York using a teletype, receiving the results back at Dartmouth College in New Hampshire. That arrangement of a central mainframe with remote dumb terminals stayed popular well into the 1970s. In the 1960s, Paul Baran and, independently, Donald Davies began investigating packet switching, which sends a message in portions to its destination without routing it through a centralized mainframe. A four-node network appeared on the 5th of December 1969, the beginning of the ARPANET, which had grown to 213 nodes by 1981 before merging with other networks to form the Internet. Modern telecommunication rests on three parts always present in some form: a transmitter that turns information into a signal, a transmission medium that carries it, and a receiver that turns it back into usable information. When multiple transmitters and receivers share one physical channel, the result is a multiplex system, and that sharing often brings significant cost reduction. Industrial laboratories pushed their own advances, including the local area network developments of Ethernet in 1983 and Token Ring in 1984.

• 7. Analogue And Digital

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  Analogue signals vary continuously with the information they carry, while digital signals encode it as discrete values, like a set of ones and zeroes. During transmission, analogue signals are degraded by undesirable noise, often expressed as a random process adding to or subtracting from the desired signal. Digital signals resist this. Unless additive noise crosses a certain threshold, the information stays intact, a key advantage over analogue. The trade-off is harsh. Digital systems fail catastrophically when noise overwhelms their ability to autocorrect, whereas analogue systems fail gracefully, growing more degraded yet still usable. Frequency-division multiplexing slices the medium by frequency, letting one station broadcast near 94.5 MHz while another sits near 96.1 MHz, each using a bandwidth of about 180 kHz. Time-division multiplexing instead hands each sender a recurring time slot, such as 20 milliseconds out of each second, and it is used in optical fibre communication. Shaping a signal to carry information is called modulation, and representing a digital message as an analogue waveform is known as keying, a term drawn from the older use of Morse Code.

• 8. The Reach Of The Network

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  The world's two-way telecommunication capacity grew from 281 petabytes of optimally compressed information in 1986 to 65 exabytes in 2007, the jump from two newspaper pages per person each day to six entire newspapers. The global telecommunications industry was about a 4.7 trillion dollar sector in 2012, with service revenue estimated at 1.5 trillion dollars in 2010, roughly 2.4 percent of the world's gross domestic product. That reach is uneven, a gap known as the digital divide. A 2003 survey by the International Telecommunication Union found that roughly a third of countries had fewer than one mobile subscription for every 20 people. The same body, formed when two organizations merged at the 1932 conferences in Madrid, ranked Sweden, Denmark and Iceland highest in access while Niger, Burkina Faso and Mali ranked lowest. The economic effects reach the smallest scale. In Bangladesh's Narsingdi District, isolated villagers use cellular phones to bargain directly with wholesalers, and in Cote d'Ivoire coffee growers share mobile phones to track hourly price swings and sell at the best moment. Starting with the operation of TAT-8 in 1988, the 1990s brought widespread adoption of optical fibre, and today's fibre cables carry 25 times as many telephone calls as TAT-8 itself.