Telecommunication

Antenna for transmission of electromagnetic signals.

Telecommunications is any transmission and reception of signals of any nature, typically electromagnetic, containing signs, sounds, images or, in short, any type of information that is to be communicated over a certain distance.
By metonymy, telecommunication (or telecommunications, interchangeably) is also called the discipline that studies, designs, develops and exploits those systems that allow such communications; Similarly, telecommunications engineering solves the technical problems associated with this discipline.

Telecommunications are a basic infrastructure of the current context. The ability to be able to communicate any military or political order almost instantaneously has been radical in many historical events of the Contemporary Age —the first modern telecommunications system appears during the French Revolution. But in addition, telecommunication is today a social and economic factor of great relevance. Thus, these technologies acquire importance such as their usefulness in concepts of globalization or the information and knowledge society; which is complemented by their importance in any type of commercial, economic-financial, professional and business activity. The mass media also use telecommunications to share content with the public, which is of great importance when it comes to understanding the concept of mass society.

Telecommunications includes many technologies such as radio, television, telephone and mobile telephony, data communications, computer networks, the Internet, radio navigation or GPS or telemetry. A large part of these technologies, which were born to satisfy military or scientific needs, have converged on others focused on non-specialized consumption called information and communication technologies, of great importance in the daily life of people, companies or institutions. state and political. It is because of this context that the current trend is the communion of telecommunications with other disciplines such as computing, electronics or telematics to design and offer these products and services, complex and multidisciplinary enough so that the border between the contribution of said disciplines is not perceived by people —despite the fact that a computer scientist, an electrician and a telecommunications operator have different disciplinary fields.

Etymology and evolution of the term

The term «telecommunication» has its origins in the French Télécommunication, a word invented by the engineer Édouard Estaunié by adding the Greek prefix to the Latin word communicare —to share— tele-, which means distance. With this term he intended to use the same word to refer to the «transmission of knowledge at a distance through the use of electricity", which until then was telegraphy and telephony, and first published it in Traité Practique de Télécommunication Électrique (Télégraphie-Téléphonie) of 1904.

Spanish successfully assimilated the loan in various spheres of public, academic, political and business life. As early as 1907, a “telecommunications” subject was taught at the Official School of Telegraphy in Madrid with the contents of telephony, telegraphy, radiotelegraphy and radiotelephony; and in 1920 Juan Antonio Galvarriato published El Correo y la Telecomunicación en España. Political life also got used to using the term and, in 1921, the government of Manuel Allendesalazar requested an ambitious plan of expansion of the «Telecommunications services», which, although it never materialized due to the Annual Disaster, demonstrates the use of the term in Spanish. In fact, at that time «telecommunications» was synonymous with modernity, for which reason it was incorporated into the name of many companies of the time such as the "Compañía Ibérica de Telecomunicación" of Antonio Castilla López in 1916 or the "Compañía de Telecomunicación y Electricidad" in 1919.

The real consolidation of the term at the international level came with the constitution of the International Telecommunication Union (ITU) at the Madrid Conference of 1932, in which “telecommunications” was defined as “all telegraphic or telephone communication of signs, signals, writings, images and sounds of any nature, by wires, radio or other electrical or visual systems or procedures (traffic lights)". the current Radiocommunications Regulations, redefines the term:

By metonymy, the study of telecommunications or telecommunications is called "Telecommunications" or "Telecommunications" interchangeably.

History

Luc-Olivier Merson, 1869.
According to the legend of Herodoto Marathon, the Philípides soldier traveled the 42 km separating Athens from Esparta carrying a message of help.

Although as we have seen, «telecommunications» as a unified study of distance communications is a recent idea, there have always been means of communication that are also studied by this discipline. Throughout history there have been different situations in which remote communication has been necessary, such as in war or commerce. However, the academic basis for the study of these media, such as information theory They date from the middle of the 20th century.

As different civilizations began to spread over larger and larger territories, an organized system of communications was necessary to allow effective control of those territories. It is likely that the oldest method of telecommunications is carried out with messengers, people who They traveled long distances with their messages. There are records that the first civilizations such as the Sumerian, Persian, Egyptian or Roman already implemented various postal mail systems throughout their respective territories.

Background

The first technologies used in telecommunication used visual signals such as beacons or smoke signals, or acoustic signals such as through the use of drums, horns or bellows.

Thus, the Greek playwright Aeschylus (525-456 B.C.) recounts in his work Agamemnon that the homonymous character from mythology communicated to the city of Argos, of which he was king, and his wife Clytemnestra, the victory of the Achaeans over Troy through a chain of fire signals that went from one point to another. The Greek historian Polybius (204-122 BC) also explains another example of long-term communications. distance, the hydraulic telegraph, which according to accounts was developed by Aeneas the Tactician in the 4th century BC. C.. It consisted of two water tanks equipped with two taps and, submerged vertically, a tablet with the signs and signals that were to be transmitted. The sender alerted the receiver with torches when both should open and close the water, in such a way that the water level indicated what message on the tablet they wanted to transmit.
However, these first technical manifestations did not result in real telecommunication systems, rather, it was not until the Contemporary Age that ways were invented to carry out remote communications. It was the postal mail, in its different manifestations, which assumed the role of communicating to people during almost all of history.

More recent is the use of optical telegraphs, considered the first modern telecommunication system as it allowed messages to be codified that had not been pre-fixed; until then, simple messages were transmitted, such as 'danger' or 'victory', without the ability to give details or descriptions. It was about structures provided with movable arms that, by means of ropes and pulleys, adopted different positions with which to encode the message. Although it was Robert Hooke who, in 1684, presented the first detailed design of an optical telegraph to the Royal Society, it was not until the early 19th century in France that it was effectively implemented. It was during the French Revolution, when there was an important need in the country to be able to transmit orders efficiently and quickly, when the engineer Claude Chappe and his brothers installed 556 optical telegraphs that covered a distance of almost 5,000 kilometers. The first line, with 22 towers and 230 kilometers, was laid out in 1792 between Paris and Lille, and in 1794, it conveyed the news of the French victory at Condé-sur-l'Escaut:

Condé has returned to the power of the Republic: the surrender has been made this morning at six.

First message of Chappe's optical telegraph.

The system, which turned out to be a success in the military field, spread throughout Europe, although with the modifications specific to each country, such as the design of Murray in Great Britain or that of Breguet and Betancourt, as well as that of Mathé, in Spain.

The hydraulic telegraph was used by Eneas el Táctico. Slimmer used by the Apaches to communicate. Horn used in South America by moche culture in the iii century. A network of optical telegraphs was installed in France in 1792.

19th century. Electrical advances

Illustration of an article by Sömmerring of 1810.
As Sömmerring's electrochemical telegraph was appreciated, it used the electricity of a voltaic battery, the high right instrument.

Although it was in 1729 that the scientist Stephen Gray had formally discovered that electricity could be transmitted, the first technical experiments did not materialize until the 19th century, when Alessandro Volta presented to the Royal Society an instrument capable of generating direct current, the voltaic pile -see the history of electricity-. For example, an early experiment in electrical telegraphy was the electrochemical telegraph created by the German scientist Samuel Thomas von Sömmerring in 1809, based on a less robust 1804 design by the Spanish scientist Francisco Salvá Campillo. This invention used electrical signals. that were sent by various metal cables, one for each letter. At the receiving end the streams electrolyzed the acid in individual glass tubes, releasing streams of hydrogen bubbles into the corresponding tube for viewing by the receiver operator.

The Telegraph

Recording Popular Science Monthly Volume 3, p. 418 (in English).
Cooke and Wheatstone single needle telegraph. When the crank was turned into a sense, the movement was replicated in the receiver.

Recording Appletons' Cyclopædia of American Biography, p. 426. 1900.
Recording of the original design of Morse's telegraph.

The electric telegraph, which was developed in the first half of the 19th century, has its origins in a multitude of experiments and new technologies, so no single inventor can be mentioned, although some important names can be mentioned.

For example, the Russian diplomat Pavel Schilling built in 1832, in his own apartment, an electromagnetic telegraph that used six galvanometers as receivers whose needles indicated the character sent. famous scientists Gauss and Weber, who in 1833 installed a telegraph line between the university and the Göttingen astronomical observatory where they both worked. They managed to communicate by moving the needle of a magnetometer, with which they coordinated time, and came to develop a 5-bit code.

However, it was not until the first patent for a telegraph that it left the laboratories. It was in 1837, when William Fothergill Cooke, who associated with the physics professor Charles Wheatstone, patented a telegraph with five electrical conductors that moved another five magnetized needles with the They had to point to one of the 20 letters on the device. In July of that same year they demonstrated their invention between Euston and Camden Town stations, but it was not until July 9, 1839 that their between Paddington station in London and West Drayton station, 21 kilometers away. This time, however, they used a variant of their invention that used only two needles and used a code of positive and negative electrical pulses to each character.
Finally, after managing to reduce the number of needles in their invention to just one, Cooke and Wheatstone founded the Electric Telegraph Company in 1846, precursor to the first telecommunications company —British Telecom—, and by 1852, 6,500 km had already been installed in England. of telegraph lines. The invention spread throughout Europe and lines were installed in various countries such as France (1845), Austria-Hungary and Belgium (1846), Italy (1847), Switzerland (1842) or Russia (1853)..

The other key couple in the history of telegraphy was formed by the painter Samuel Morse and Alfred Vail, both Americans and contemporaries of Cooke and Wheatstone. Samuel Morse had heard about electromagnets in 1832 during a trip, and it occurred to him to use them to make a pencil move to mark the message sent on a piece of paper. In 1835 he was appointed professor of literature, art and drawing at New York University, so he could devote himself to building the first prototype of it. However, it would not be until 1837 when together with Alfred Vail he achieved a fully operational prototype. In 1843 they obtained US$30,000 to finance the construction of a telegraph line between Washington and Baltimore, which was inaugurated on January 1, 1845.
This also consolidated the use of the telegraph in the United States. In this country, between 1861 and 1865, the Civil War took place, in which thousands of kilometers of telegraph lines were laid and all the technical advances of the time were exploited, such as telegraphy, aerostatics, railways or steamships. By 1866 the company that had unified the market—the Western Union Telegraph Company—had more than 2,250 offices and 120,000 kilometers of lines, and offered both personal and professional services, such as the Associated Press news service.

As the use of the telegraph was consolidated, new improvements and functionalities were added. It is worth noting the telegraph model patented by David Edward Hughes in 1855 with which up to 45 words per minute could be transmitted instead of the 25 words per minute of the Morse system. It was a system that, using a wheel with the letters of the alphabet, directly printed the transmitted message in an understandable language. Another great advance was introduced by Émile Baudot in 1874, who invented a type of time division multiplexing that allowed several simultaneous communications using the same line; or Tomas Edison, who had worked as a telegraph operator since he was fifteen and invented a quadruplex communications system in 1874 with which to send four simultaneous telegrams over the same wire.

The telegraph established itself as the preferred means of communication. If in 1865 the total number of telegraph lines of the members of the International Telegraph Union was 500,000 kilometers and some 30 million messages were sent, by 1913 there were 7 million kilometers of lines and 500 million telegrams were transmitted. European countries, such as England or Spain, mostly adopted the Cooke and Wheatstone system, and the Morse system was preferred in the rest of the world. This was established for international telegraph lines at the Paris Conference of 1865 when it was established. the International Telegraph Union. Later, in 1903, this same body recommended at the London Conference the use of the Hughes system for the busiest lines and the Baudot system for services with more than 500 daily telegrams.

The telegraph had established itself as the quintessential means of communication, and had a notable influence on other future technologies to the point of conditioning its name: 'talking telegraph' or 'improvements in telegraphy' —telephone—, or 'wireless telegraphy' -radiocomunication-.

The phone

One of the most successful inventions of the 19th century, which is still widely used today, was the telephone. This invention made it possible to communicate using the voice, although initially it was not bet on its development due to the success and power that the telegraph already had. As in many other cases, the invention and development of the telephone is not due to a single person, and several inventors developed technologies related to telephony. In fact, the first speculations about the possibility of remote voice transmission date back to long before the invention of the telephone. For example, Robert Hooke speculated about remote voice transmission, but his experiments with tightropes were not very successful; and G. Huth first used the word 'telephone' in A Treatise concerning some Acoustic Instruments and the use of the Speaking Tube in Telegraphy (1796) suggesting the use of acoustic instruments to communicate at a distance, as well as the use of a tube in telegraphy.

But it wasn't until the development of a specific technology when we can talk about the first pioneers: Antonio Meucci, Philipp Reis, Innocenzo Manzetti, Elisha Gray or Alexander Graham Bell, among others. The beginning of telephony was marked, in fact, by numerous legal battles for the authorship of the primitive telephones, so it is preferable to use chronological order when listing the different technical advances or their patents.
Thus, in 1856 Antonio Meucci installed a device in his home that connected the bedroom with the basement with which he could talk to his sick wife, which he called a «teletrofono» -«teletrofono» in Italian—, and which was supposedly published in the press. Be that as it may, the first device to be called a “telephone” —“telephone” in German— was the one presented by Philipp Reis in 1862, who used a membrane of leather for your device. The result was a telephone that allowed electric notes and simple sounds to be transmitted, but on which it was practically impossible to speak. Two years later, in 1864, Innocenzo Manzetti invented his own 'talking telegraph'. —télégraphe parlant in French— which allowed voice transmission, and was published by the media.
However, the first patent for a telephone system was obtained by the American Alexander Graham Bell in 1876, with which he obtained exclusive exploitation of the invention until 1893 and managed to monopolize the market in the United States. Joined. Another inventor, fellow American Elisha Gray filed a patent application for a telephone system on the same day as Bell—actually his investor, Hubbard—but was a few hours late. It should be noted that Bell was involved in up to 600 lawsuits for the authorship of the phone, including Meucci, Gray, Edison or the then all-powerful Western Union, but he won all the trials. The authorship of the phone is still a matter of controversy and differs by country.

Be that as it may, the reality is that the market did not know how to see the potential of the invention, described as a "toy", since all communication needs were resolved with the telegraph, which also left written testimony of the transmitted. Thus, the real milestone for Bell and his associates was to have started, and then monopolized, a market as important as the telephone market, which came to be almost completely controlled by American Telephone & Telegraph Company—initially the Bell Telephone Company. Of course, that happened in the United States, but the development in the rest of the world was made in the image and likeness of the American case.
Bell, a teacher of deaf-mute children and knowledgeable about the physiognomy of the human ear, was looking for a way to build a telephone —he thought of an "electric ear"—, but all the experiments of the time tried to invent telegraphy harmonica with which to transmit a multitude of telegraphic conversations in the same thread, each one with a note. Bell's efforts caused him to lose most of his students to devote time to his experiments, so the parents of his only two remaining students, his future father-in-law Gardiner Hubbard and Thomas Sanders, began funding him if he focused on finding a harmonic telegraph. Bell, however, continued to research his mechanical ear along with Thomas Watson, a skilled builder who covered Bell's clumsiness with electrical gadgets. In June 1875 they managed to identify a metallic sound through the invention, and on February 14, 1876 Hubbard requested the patent under the name of "improvements in telegraphy", in which it was mentioned that it would be used to send voice or other sounds telegraphically. On March 10, Bell received patent 174,465 and three days later he would utter the famous phrase "Mr. Watson, come here, I need you " through his phone.
But the context in the 1870s was not the most propitious for large investments, mainly due to the economic crisis of 1873 and the consolidation of the telegraph - it is said that Western Union itself refused to buy the telephone patent. Thus, Bell and Watson focused on making various demonstrations of their invention, including that year's World's Fair, while Hubbard began marketing the product at low cost and getting conferences for Bell. A year later, in 1877, they formed the Bell Telephone Company, dividing the profits in 3 tenths for each one —Bell, Hubbard and Sanders— and one tenth for Watson; and at the end of that year they already had 3,000 telephones installed and many debts. It wasn't until the incorporation of Theodore Vail—Alfred Vail's brother—that the company began to take off, but by that year there were already 1,730 competing companies in the United States, including Western Union, which had recruited Edison to improve Bell's technology. The situation remained precarious for two years, during which Watson invented the telephone ringer and a telephone was installed in President Hayes's office; until in 1879 the Supreme Court sided with Bell in his case against Western Union, so he kept his 56,000 customers for a total of 133,000 subscribers. As of that year, the group led by Vail took control of the entire US market, since they still had 17 years until the patent expired to exclusively exploit the invention, and in fact the $50 shares were now worth more than $1,000. In those 13 years they reached 230,000 customers and were refounded as American Telephone & Telegraph Company. The company continued to grow, within the fluctuations of the market, until it became a true monopoly, the main difference between the US and European markets in which the monopoly of these infrastructures was exercised by the State. The company founded Bell Laboratories, bought much of Western Union, and remained one of the largest companies in history until antitrust actions by the United States Department of Justice succeeded in separating the company into local entities — Baby Bells—in 1984.

Another great milestone in telephony was the invention of hand switching by Tivadar Puskás.

Submarine cables

The development of telecommunications in the last third of the 19th century was marked by international cooperation in telecommunications, It had its beginnings in the daily activities of the telegraph companies that, on the very borders of the different nations of the time, exchanged and translated cross-border messages. However, the seas and oceans constituted a natural border difficult to avoid.

During this century, the use of transmission media in simple forms, made of iron or copper, and in most cases without external coating, was investigated. It should be remembered that the way of investigating at the time was trial and error, in which dozens of materials were tested to solve a problem until the optimum was found. In 1847 Werner von Siemens and others invented methods of coating gutta-percha cables to make them waterproof.

The first submarine cable was the one that was launched in the Pas de Calais —English Channel— between Cape Gris-Nez —France— and Cape Southerland —England— by the brothers John and Jacob Brett. It was a telegraph cable that was laid by the tugboat Goliaht on August 28, 1850, but it was sectioned by a local fisherman shortly after, who exhibited it as a trophy. The following year a cable was released again, which was luckier than the previous one, made up of 4 copper wires of 1.65 mm in diameter covered with hemp and reinforced with 10 galvanized iron wires of 7 mm in diameter. Due to the success of this first cable, the idea spread and in 1852 Wales and Scotland were joined with Ireland, and the following year Belgium and Denmark were connected through the North Sea. Cables were also laid between Corsica and Sardinia, Italy and Corsica, Tasmania and Australia, and many other locations. In 1860 there was already a direct link between England and India that saved numerous waterways such as the Suez Canal.

However, the great challenge of the time was laying the first transatlantic telegraph cable, a true engineering feat of the time. On August 7, 1857, the warship Agamemnon tried to drop some 3,200 kilometers of cable made with a core of seven gutta-percha-coated copper wires —up to 12.2 mm— and an outer reinforcement of 18 iron wires.. However, 10 days after leaving Ireland, the cable broke at a depth of 3,600 meters —2,000 fathoms—, so the project was abandoned. The following summer the laying was retried, but with a different approach: the Agamemnon and the Niagara would meet in the middle of the Atlantic, each with half the cable, and after joining both ends on June 28, they each departed in opposite directions; the Agamemnon cable broke 230 km into the journey, so both anchored in Queenstown —Newfoundland— awaiting orders. One month after the first attempt, on July 28, 1858, both ships repeated the operation once more and managed to lay the 2,340 km of cable necessary to link Dowlas Bay —Valentia, Ireland— and Trinity Bay —Newfoundland—, to where both ships arrived on August 5. That same night the first telegram was sent announcing the arrival, as well as various congratulations. However, barely a month later, on September 3, the cable failed due to a voltage surge. Despite multiple failures, businessman Cyrus Field, owner of the Atlantic Telegraph Company, managed to charter a new expedition to launch another cable. After the Civil War, on July 23, 1865, the Great Eastern ship —the largest of the time— set sail from Valentia with 3,700 km of cable, 3 times thicker than the previous one, bound for Newfoundland. At the beginning of August, when more than 1,900 meters of cable had been laid, the ship's technicians discovered a manufacturing defect that forced them to refloat several kilometers of cable to replace it, with such bad luck that it broke during the repair work. After three failed attempts to recover the cable, after managing to find it at the bottom of the ocean, the ship returned to Ireland. Finally, in 1866, the Great Eastern successfully launched the submarine cable, and to top it off, she recovered the cable lost a year earlier from the bottom of the Atlantic and completed it to have a second cable across the ocean.

Since then, many more submarine cables have been laid throughout the entire planet, improving existing technologies to the use of today's fiber optics. It is estimated that today 90% of Internet traffic is transmitted by submarine cables – the rest by satellites.

20th century. War and electronics

Embrasement de la Tour Eiffel pendant l’Exposition universelle de 1889Georges Garen, 1889.
The universal exhibitions of the time, which promoted scientific progress and confidence in progress, were true catapults for advances in telecommunications.

At the end of the 19th century, in the so-called Belle Époque, a feeling of optimism, enthusiasm and confidence spread in the course of progress and the potential of science and technology —positivism and scientism—. The rise of the bourgeoisie and the middle classes meant an irruption of people outside the aristocracy in political power, and even the proletariat felt some confidence in the future as the workers' struggle grew and achieved small gains. World's fairs followed, promoting a vision of global progress without borders, and news from the outside world was more easily disseminated thanks to the railway, the submarine cable and the telegraph, the telecommunication system that dominated the era. It was even believed that everything had already been invented, despite the fact that the last years of the xix century and the first of the xx were especially prolific for science and technology: the Lumière brothers screened the first motion picture in 1895; medicine was advancing with discoveries such as the one carried out by Ronald Ross, who discovered how malaria was transmitted; the physicists Henri Becquerel, Marie Curie and Pierre Curie discovered the radioactivity of uranium and radium respectively, a discovery that earned them the Nobel Prize in 1903; aviation was born in the United States at the hands of the Wright brothers, etc.

Radio communication

Telecommunications was also nourished by the remarkable scientific experiments of the time. Thus, Heinrich Rudolf Hertz reformulated Maxwell's equations, which predicted the propagation of electromagnetic waves, and in various experiments in the 1880s, producing and measuring his own waves, demonstrated that these 'waves' Hertzian waves', as these electromagnetic phenomena were called at the time, could be reflected, refracted, polarized, diffracted, and interfered with. a base that allowed the implementation of a new telecommunication system, superior to the telegraph in efficiency and effectiveness: radio communication or "wireless telegraphy".

The invention of radio communication, as with the telephone, is disputed among various inventors, including Edouard Branly, Nikola Tesla, Aleksandr Stepánovich Popov and Guillermo Marconi; This article narrates the events chronologically. In addition, as happened with the telegraph or the telephone, the credit for this type of invention is usually given to whoever patents and markets the new system, and not to whoever discovers a certain phenomenon in a laboratory.
For example, in 1891 Edouard Branly discovered the coherer, a simple glass tube filled with metal filings that allowed the passage of electric current when electromagnetic waves struck it, and that would be used by contemporary inventors to detect these waves. In fact, in France Branly is considered the inventor of radio communication.
The prolific inventor Nikola Tesla, who fought against Thomas Alva Edison in the war of currents, also carried out various experiments and designed several inventions that allowed the effective transport of electromagnetic energy, but he focused on the industrial transport of electrical energy and did not seek an application of his inventions for the transport of information. Thus, between 1891 and 1893 he presented various works and experiments that allowed the effective transmission of electrical energy in the 5.1 MHz band.
Oliver Joseph Lodge also influenced other inventors in a notable way, especially due to a lecture on Hertz's experiments that he gave in 1894 at the Royal Institution in London. But he also made notable inventions that allowed the first systems to be built shortly after. of effective radio transmission. Thus, in May 1897 he applied for patent number 11,575, for a radio tuning system —filtering a single frequency band— based on the phenomenon of electromagnetic resonance.

Russian physicist Aleksandr Stepanovich Popov read Lodge's lecture on Herth, which inspired him to begin research on the subject. Popov, who was a professor of physics at the Imperial Russian Torpedo School in Kronstadt, built several prototypes since 1894 and made a demonstration in 1896 before the Russian Physical and Chemical Society in which several sources state that the words "Heinrich Hertz" were transmitted by wireless telegraphy, while other sources do not contemplate the possibility that this It could have happened before mid-1896, when Marconi was already making transmissions. Be that as it may, Popov is today considered the inventor of radio communications in Russia, where every May 7 is celebrated on the day of the Radio.

However, it was Guillermo Marconi who patented, designed and implemented an effective radio communication system around the world under his supervision and closely linked to communications at sea. Marconi, with financial support from his father, began developing a system of wireless telegraphy at the young age of twenty-one, in 1895. He experimented empirically with Branly coherers and home-made antennae on his father's farm., achieving transmissions up to a kilometer away, until in 1896 Marconi traveled to London to continue his experiments. There he had the support of William Henry Preece, chief engineer at the British Post Office who had also carried out experiments. telegraph and telephone, and under the umbrella of the company tests were carried out in 1896 and 1897 in which transmissions were achieved at distances of 7 km on land and 14 km over salt water. The success was such that in that same year Marconi founded the Wireless Telegraph and Signal Company Limited, managed to progressively increase the range of its equipment —it took more than two years to realize the importance of matching the size of the transmitting antenna to the of the recipient—and he shipped and installed them all over the globe. When companies like the German Telefunken, the result of the union of Siemens & Halske and AEG in 1903, increased the pressure on Marconi's project, he stopped marketing his equipment and focused on deploying a network of earth stations, which provided coverage on the main trade routes, and equipping ships not only with the company, if not with operators on the payroll who only communicated with the stations of their own network; this practice ended with the approval at the First International Radiotelegraphic Conference in 1906 of the Radiocommunications Convention and its annexed regulations, but by then the company de Marconi already mastered communication at sea.

As it happened with the telegraph, several episodes demonstrated that radiotelegraphy was a tool with which to avoid great human tragedies, recounting another chapter of great importance in the history of the discipline and its acceptance as a pillar of modern society.

At the beginning of the 20th century, the teletype appeared which, using the Baudot code, allowed text to be sent on something similar to a typewriter and also to receive text, which was printed by types moved by relays.

The term telecommunication was defined for the first time at the joint meeting of the XIII Conference of the UTI (International Telegraphic Union) and the III of the URI (International Radiotelegraphic Union) that began in Madrid on September 3, 1932 The definition then approved of the term was: "Telecommunication is any transmission, emission or reception, of signs, signals, writings, images, sounds or information of any nature by wire, radioelectricity, optical means or other systems electromagnetic".

The next revolutionary device in telecommunications was the modem, which made it possible to transmit data between computers and other devices. In the 1960s, telecommunication began to be used in the field of information technology with the use of communication satellites and packet switching networks. The following decade was characterized by the appearance of computer networks and the protocols and architectures that would serve as the basis for modern telecommunications (in these years the ARPANET appeared, which gave rise to the Internet). Also in these years began the boom in the standardization of data networks: the CCITT works on the standardization of circuit-switched and packet-switched networks and the International Organization for Standardization creates the OSI model. At the end of the seventies, local area networks or LANs appeared.

In the 1980s, when personal computers became popular, digital networks appeared. In the last decade of the 20th century, the Internet appeared, which expanded enormously, helped by the expansion of fiber optics; and at the beginning of the 21st century we are experiencing the beginnings of the total interconnection to which telecommunications converge, through all kinds of devices that are increasingly faster, more compact, more powerful and multifunctional, and also new communication technologies wireless as wireless networks.

Contemporary period

Content of the discipline

The physicist James Clerk Maxwell, who fully modeled the concept of electromagnetic wave through his equations.

Fourier's transformation, invented by engineer Joseph Fourier, allows us to analyze the frequency spectrum of a signal.

The bibliography that covers the verification criteria of this section may be found in the bibliography section.

Theoretical basis

Telecommunications is based on other disciplines from which it obtains very powerful tools to model the different systems with which to transmit and receive the information that makes up each communication and to proceed with its implementation.

• Maths: As a formal science, mathematics offers the means of formally expressing the models involved in the transmission of information and tools for its analysis, such as algebra, calculation and differential calculation, statistics... They highlight tools such as the Fourier transformation or the Laplace transformation.
• Physics: Physics provides the study of the environment around us and on which telecommunication systems are established. Highlights electromagnetism. His mathematical base was developed by Scottish physicist James Clerk Maxwell in his work Treatise on Electricity and Magnetism (1873), which introduced the concept of electromagnetic wave and allowed an adequate mathematical description of the interaction between electricity and magnetism through its fundamental equations that describe and quantify the fields of forces.
• Theory of information: Allows to evaluate the capacity of a communication channel according to its bandwidth and its signal-ruid ratio. He was the laboratory scientist Bell Claude E. Shannon who with the publication in 1948 of the study entitled A mathematical theory of communication formed the mathematical models used to describe communication systems.
• Systems theory and Control theory: These interdisciplinary studies allow the modeling of different telecommunication systems. The systems theory models the individualized contribution of each element that forms a system while the control theory modeles its evolution in time, which can be automatic.
• Theory of tails: Allows to model the quality of service with which users enjoy communication services.
• Computer: Allows to schedule communications protocols or simulate them.
• Electronics: Telecommunication systems are based on both analogue electronic circuits and digital circuits, driven through the massive introduction of integrated circuits, and which has enabled the full advantage of digital signal processing. For example, filters that can discriminate against certain frequencies of a signal can be implemented; this is what is done by tuning a radio or television.

Information, communication and language. Digitization

The telecommunication objective is to establish a distance communication, and all communication is associated with the delivery of certain information, since from the technical point of view even the phatic function contributes information to the message, through of a language.

This information is obtained from the so-called information sources: sound, image, data, biomedical signals, meteorological signals... and ultimately any form of analog, discrete or digital signal. These sources are processed and treated in order to proceed to their study both in time and frequency and thus find the most efficient way to transmit them. Criteria such as the bandwidth of the signal or the transfer rate are met in order to transmit the greatest possible information with the least number of resources without interference or loss of information. Thus, compression techniques are applied that allow the volume of information to be reduced without seriously affecting its content.

Example of digitalized signal.
Digitalization allows the processing of physical signals — sound, image... — with computers.

One way of obtaining this information that has become very important is digitization, which consists of characterizing analog signals with digital signals. The process consists of sampling the signal enough times so that the original signal can be reproduced again with the interpolation of its samples. Using the Nyquist-Shannon criterion, a fundamental theorem of information theory, it follows that it is only necessary to sample the signal at twice its frequency; For example, in the human voice, which has a bandwidth of about 4 kHz, it is only necessary to sample at 8 kHz (8000 samples per second). The next step consists of quantifying these samples, that is, associating them with a pre-established discrete value according to the code used —in this step of the process, part of the information is lost, but small enough to be negligible. Finally, in the encoding, each value is represented with a symbol of a binary code.

Finally, a language is necessary in which to encode that information and that is known by both the sender and the receiver. In the field of telecommunications, this language is called the communication protocol, which not only defines the language used, but also the technical characteristics of the communication.

Communication systems

A communication system or transmission system is any system that allows communication to be established through it. This definition includes both the transmission network, which serves as a physical support, and all the elements that allow information to be routed and controlled:

• Emitters: is the part of the system that encodes and emits the message. It can be an antenna, a computer, a phone...
• Receptors: is every device capable of receiving a message and extracting the information from it. It's the case of a radio, a television...
• Means of transmission: The physical support through which the information is transmitted, either light (guided medium) or wireless (non-guided medium).
• Repeaters: They are devices that amplify the signal that comes to them, so you can set communications over a long distance.
• Switches: They are devices en route each network plot to your destination on a computer network.
• Encaminators: (routers In English: They are devices that allow you to choose at every moment which is the best way for network plots to reach your destination in a network with TCP/IP support.
• Flltros: Devices that allow the passage of certain signal frequencies but prevent the passage of others. They are used to tune (multiplex) channels on a radio or on a television, for example.

A transmission system is modeled mathematically by both systems theory and control theory. In this way, the different contributions of the components can be assessed separately and the mathematical functions that they provide. In this sense, a whole set of components can be reduced to a single net contribution; the output is then said to be the response of a system to an input or that the system responds to the input with some output. In a similar way, the queuing theory also takes on great relevance, since it allows relating the services that can be provided with their quality of service and the resources necessary for their implementation.

An effective communication system is one that satisfactorily satisfies three essential needs:

• Delivery: The system must transmit all the information there. In addition, it is sometimes necessary for the system to ensure that such information will only be received where it is intended.
• Exact: The system must deliver the information accurately and without modifying it. The data that are altered in the transmission must be able to recover through detector codes and error fixers or other techniques.
• Puntuality: The system must deliver the information at the time interval planned for it. In the case of real-time video, audio or voice transmissions, timely delivery means delivering the data as it occurs without significant delay.

To achieve these objectives, the communication system is designed with components that allow an adequate quality of service to be given to the application of the system, designing and implementing it with adequate elements. However, it is not possible to control all those involved in the transmission, since there are phenomena that alter the quality of the service: impulsive noise, Johnson-Nyquist noise (also known as thermal noise), propagation time, channel transfer function not linear, sudden signal drops (micro-outages), bandwidth limitations and signal reflections (echo). However, many modern telecommunication systems take advantage of some of these imperfections to improve said quality.

Transmission media

A can phone chart.
On a tin phone the vibrant rope is a medium of guided transmission. The air between the can and the mouth of the speaker works like a non-guided medium.

A transmission medium is the channel that allows the transmission of information between two terminals of a transmission system. The transmission is usually carried out using electromagnetic waves that propagate through the so-called communication channel. Sometimes the channel is a physical medium and other times it is not, since electromagnetic waves are susceptible to being transmitted through a vacuum.

They can be classified into two large groups: guided transmission media and unguided transmission media. In addition, transmission media are classified according to their characteristics of attenuation, noise addition, distortion, or delay of the signal that contains the information, so each transmission medium will be suitable for a specific application.

The guided transmission media are those made up of a solid channel through which information is transmitted in the form of a variation of a physical quantity. Thus, although rudimentary, the rope that joins the two ends of a tin can telephone constitutes a guided transmission medium, in this case of sound waves.
On the contrary, an unguided transmission medium is the one that serves as a support for the variation of the magnitude to occur, but does not direct it along a specific path. This is the case, in contrast to the previous example, of the sound when we speak with another person face to face.

Guided Streaming Media

In the current telecommunication context, most of the guided media are cables made of different metals such as copper. The telegraph network used malleable bare cables suspended from crossbeams on poles. These types of cables were exposed to interference and short circuits, but considering the low speed of the telegraph, they worked conveniently well. To avoid these problems, the cables were covered with insulation, generally plastic. The most common was telephone cable made up of two parallel copper wires, although currently the braided cable is used, which is more resistant to electromagnetic interference. With the expansion of telecommunications, it was necessary to extend cables to interconnect the different continents, so submarine cables were installed.

The twisted pair is the most economical and most widely used guided medium for general applications. Invented by Alexander Graham Bell in 1881, it consists of two insulated copper wires, which are twisted helically. Since two parallel wires constitute a simple antenna; in the twisted pair, the waves of different turns cancel each other, so that the radiation of the cable is less effective and reduces electrical interference, both outside and from nearby pairs. This type of cable may or may not be protected by a protective metal mesh, such as STP (Shielded Twisted Pair), UTP (Unshielded Twisted Pair, pair unshielded twisted) or FTP (Foiled Twisted Pair, twisted pair covered in metal foil).

The coaxial cable is also made up of two conductors, but in this case one of them is an internal wire and the other is a metallic mesh that surrounds it. The two conductors are separated by an insulator and the shield has a plastic cover.

The optical fiber is a link made with a very fine thread of transparent material with a small diameter and covered with an opaque material that prevents light from dissipating. Through the core, usually made of glass or plastic, pulses of light, not electrical ones, are sent. There are two types of fiber optics: multimode and single mode. In multimode fiber, light can travel through more than one path, since the core diameter is approximately 50 µm. On the contrary, in single-mode fiber only one mode of light propagates, the light only travels along one path. The core diameter is smaller (less than 5 µm).

Unguided media

Unguided means of transmission include those that use variations of the electromagnetic field, a physical manifestation of electromagnetism, as support to transmit information. At the end of the 19th century, various experiments succeeded in carrying out communications through radio waves. Although, the first transatlantic wireless communication was established in 1901 by the engineer Guillermo Marconi, using designs by the scientist Nikola Tesla. From this moment on, radio communication took shape and was promoted in the second decade of the century, with the sinking of the Titanic in 1912 or the First World War in 1914 as background scenarios that demanded this type of communication.

With radio communication telecommunications can be established through the so-called radio frequencies, the least energetic part of the frequency spectrum. The transmission and reception of radio waves are carried out with an antenna, a device that transforms variations in the voltage applied to it into electromagnetic waves and vice versa. The services that can take advantage of this technology are radio broadcasting, television, mobile telephony or communications between radio amateurs.

Frequencies between 300 MHz and 300 GHz (UHF, SHF and EHF) are called microwaves. In telecommunication, microwaves are currently widely exploited as they easily pass through the atmosphere with less interference than other longer wavelengths and this spectrum has a greater bandwidth, so more bands can be established. For example, microwaves are used in news broadcasts to transmit a signal from a remote location to a television station using a specially equipped van. The 802.11 standard also uses microwaves to, among other things, implement Wi-Fi services.

In practice, a radio communication can be millions of kilometers away; For example, in space exploration, data from space probes beyond 100 au, such as the Voyager mission, continue to be received via the DSN deep space network.

The communications satellites deserve special mention for the role they play in today's telecommunication. Since the launch of Telstar 1 in 1962, satellites have been used to relay communications over long distances. The first major application for communications satellites was long-distance telephony, using a geosynchronous satellite as the connection between nodes in the telephone network. Other services such as mobile satellite telephony, satellite radio, satellite television and satellite Internet were later adapted.

Basic communication techniques

Communications networks tend to be complex when the number of users of these grows considerably, as occurred in the early s. XX with the switched telephone network. Historically, there are several objects and techniques that have made it possible to reduce the necessary resources of the networks and increase the capacities of the already existing ones. In fact, the subscriber loop is usually a copper pair, which was invented in the late s. XIX for telephony, but that can still be used today for certain ADSL or IPTV services, much more advanced technologies than the telephone.

By switching the different nodes that exist in the network are connected, allowing the most efficient path to be chosen between the two terminals. Initially, switching was carried out manually using circuit switching. The operator established a physical connection between the incoming and outgoing line with a cable at the customer's request. Automated switching systems were later developed for privacy reasons, such as the Rotary system. Packet switching refers to what is done in computer networks with data packets, where each node or router chooses the most appropriate path for the information; similar to what is done in the postal mail.

Another widely used technique is modulation, which allows the information contained in an electromagnetic wave to be inserted into another called carrier wave. In this way, certain technical problems that appear when transmitting certain signals are solved, such as the one associated with the size of the antenna. This must have the size of the wavelength of the signal that it radiates; By modulating the signal on a higher frequency carrier, and therefore shorter wavelength, a smaller antenna can be used. It also has important applications in signal multiplexing and is a way to reduce signal distortion during transmission. Modulation is the technique used in AM and FM broadcasting, for example.

Lastly, through multiple access media techniques, the same transmission medium is used to send several communications, in such a way that the number of cables used is significantly reduced or free space is used in a shared and orderly way. For example, multiplexing divides the transmission capacity of a medium into slots or windows for each transmission. In the case of time division multiplexing, messages are divided into segments and a time window is assigned for each transmission, which is recovered by synchronizing both ends. It is used, for example, in GSM mobile telephony. In frequency division multiplexing, what is divided into windows or slots is the frequency spectrum, modulating each transmission in a different frequency in such a way that they do not overlap, and it is recovered using an electronic filter for each frequency. It is used, for example, in FM broadcasting where dozens of radio channels are broadcast over the air at the same time but only one is heard on the receiver.

Telecommunication networks and services

A telecommunications network is the set of all the systems necessary for the exchange of information between the users of the system. These systems are precisely the items discussed so far in this article. Thus, on a set of transmission media, a transmission system is implemented through processing, multiplexing and modulation technologies; and some transmission protocols are designed that allow establishing communication with which to carry out an effective exchange of information between users.

There are different ways of classifying telecommunication networks, among which are:

In each network, which will present an appropriate topology, a distinction is usually made between the access network, in which the terminals of the network through which they access the users; and the transit network or network core, where the necessary systems are located to establish communication and prevent the loss of information —the network nodes and other telecommunication links.
In the simile of the postal mail, the mailboxes and the postmen would be the access network in which each user delivers the information and this is delivered to the users; while the post offices, central offices and transport trucks between municipalities would be the transit network, where it is decided what to do with each letter so that it reaches its destination in full.

Different functionalities are implemented on these communication networks; A telecommunications service is a set of services that the user receives from the network. Again in the simile of postal mail, the different services could be sending a letter, a package or a document letter -or burofax-; different services that take advantage of the same network. Telecommunication services can be classified into:

Voice and data networks and services

The traditional application of communication is voice and data transmission, since they allow two people to exchange messages almost instantly and effectively; with important applications in people's lives, in economic management, in emergencies or in war, for example. They are early systems of this type of network from the telegraph network or the teletype network (telex) to communication with homing pigeons or messages by semaphore.

The traditional public telephone network is known as Switched Telephone Network; it is said 'public' because access is free to any interested party and not because it is publicly managed, although it may be. In this network, telephones are used as network terminals, through which the users speak, and it is connected by the subscriber loop to the local distribution centers; thus forming the access network. The different telephone exchanges are interconnected with each other through larger ones in a hierarchical manner, forming the core of the network. They are circuit switching centers in which a fixed and exclusive channel is established for each communication and which does not disappear until it ends. Traditionally the connection of the circuit was physical, either by manual commutation or by a Rotary commutation system; but currently it is established digitally in digital telephone exchanges. Thus, the voice is digitized with 8 bit at about 8 kHz.

If you want to share data between several computers you will have to establish a computer network. A local area network is an interconnection of computers and peripherals with the aim of sharing both information and resources, such as printers or servers. In this case, networks use standards such as Ethernet or Token Ring and transmission media such as twisted pair cable or coaxial cable. However, a wide area network has a larger extension, like an entire country for example, and is established by large companies for their private use or by ISPs to offer Internet services.

Radio and TV broadcast networks and services

The radio and television are, along with newspapers, the so-called mass media since they are diffusive forms of communication in which a Large numbers of people get information from few sources. A broadcast network is a network oriented to deliver to various points, simultaneously and synchronously, an identical copy of the same information that has been generated by a point. In radio and television networks, since the atmosphere is a single transmission medium, different messages can only be sent using, typically, frequency multiplexing. In the receiver it filters or 'tunes' one of the signals and is demodulated to reproduce it in its entirety. This is the case of analog television, DTT or satellite television; as well as AM and FM radio broadcasts.

Other means of retransmitting radio and television broadcasting are cable television, which uses fiber optics or coaxial cable for transmission; or IPTV, which uses data services over the telephone network such as digital subscriber line (xDSL). In these cases code division multiplexing is used.

Broadband multiservice networks and services: quadruple play

The term broadband refers to a large number of data transport technologies that ISPs call this way to make it easier for customers to understand; but that ultimately offer the same service to the user, but with a different quality of service, which is why they are named in the same way for their marketing. Thus, it includes technologies that allow an Internet connection of "high" speed such as digital subscriber line (xDSL), lines based on fiber optic or hybrid fiber optic and coaxial; or wireless connections such as 3G mobile telephony or WiMAX.

The triple play refers to the packaging over IP protocol of services such as voice (VoIP with IP telephones), television (IPTV) and broadband in a single supply package and, therefore, a single product sale of services to the user; The natural evolution of the concept, quadruple play, includes the use of mobile networks to provide these services. In this way, these services are offered to the user using similar systems and technologies, which has come to be called technological convergence of ICTs. The total implementation of this type of network structures would result in the so-called next generation network.

Telematic networks and services. Internet

The telematic services are those that use both computer and telecommunication systems, such as those offered in computer networks such as the Internet, the “network of networks”. This is a set of a large number of communication and computer networks interconnected with each other in a decentralized and voluntary way. Each network that makes up the Internet is designed with architecture and technologies that can be very different; The success of the Internet as a global system is based on the fact that all these networks use the same communication protocol, the same 'language', the Internet protocol family. The IP protocol is capable of routing data traffic on the Internet as if it were a single logical network using identifications for each machine (IP address) while the TCP protocol allows effective transmission of this data to be managed without loss. Other important protocols for the operation of the Internet are, for example, HTTP, SMTP, SSH, FTP...

A common mistake is to confuse the different services that can be accessed over the Internet with the Internet itself. For example, the World Wide Web, known as the Web, is a set of protocols that allows viewing hypertext files hosted on other machines; but the confusion between 'Internet' and 'the Web'. Other services would be sending email (SMTP), file transmission (FTP and P2P), online conversations (IRC), instant messaging, content transmission and multimedia communication -telephony (VoIP), television (IPTV)—, electronic bulletin boards (NNTP), remote access to other devices (SSH and Telnet) or online games. In fact, an Internet service provider is a company that connects the devices of home users to the rest of the Internet, allowing it to access said services.

Other professional and academic networks and services

There are many other networks that offer more specific services to companies, academic or research institutions, etc. As an example, one can mention

• Intranets, ATM networks or storage networks of private companies;
• Academic and research networks such as GÉANT, Internet2, RedCLARA or the Deep Space Network; or
• Professional networks such as police radio, firefighters, fans, etc.

Influence of telecommunications

The development of telecommunications has taken place almost exclusively during the Contemporary Age, and its influence has been felt in the development of multiple dimensions of human activity: society, economy, politics, peace and security. war and, ultimately, history.

The consolidation of telecommunications as a basic infrastructure has turned them into a historical factor in themselves:

«Henceforth the position of a nation in the world will be conditioned by three factors: oil, transport and telecommunications».

United States President Woodrow Wilson at the 1919 Paris Peace Conference.

But telecommunication exceeds a merely testimonial approach until it has managed to almost completely eliminate space and time.(Hernández 1974, p.244)

Influence on technology

Political influence

Photograph by Otto von Bismarck in 1890.
Otto von Bismarck, a key figure in the formation of Germany, was depleted that all the affairs of the State should rest on him, given the closeness to them that propitiated the telegraph. Thus he came to say that “It's the nicest thing to be at the bottom of the woods, where not a person or a telegram can bother me.».

Telecommunications emerged as an instrument with which to centralize state power and thus achieve centralized economic, military and bureaucratic management. In fact, the use of telecommunications within the the Administration of a state can serve as a very effective means of control: "They encourage the development of the telegraph because this is the most powerful instrument of a despot who wishes to control his officials".

Such is the importance of telecommunications as a key factor in the government of towns and states that the telegraphic means were from their conception object of an exclusive State monopoly —except for some notable cases such as that of the United States. For example, France began in 1837 to punish any distance communication with signals with prison terms or large fines; since during the Rebellion of June 1832 it was concluded that had the rebels had access to the telegraph they would have posed a great threat.
Without going any further, Curzio Malaparte pointed out in Technique of the coup d'état of 1931 that it was enough for a handful of men to seize some key State structures, such as the telegraph and telephone exchanges, to achieve their effective control. In an analogous way, Trotsky believed that a revolutionary attack should not target the centers of state power such as the Duma, but rather its basic infrastructures such as railways, power plants or telecommunication centers. This conception of the The revolution, which aims to take control of the state's technical infrastructure, has been put into practice on various occasions: in the May 1926 coup in Poland, or in the 1932 attempted coup in Spain, among others.

Over time, States allowed citizens and companies to use the excess traffic in their telecommunication networks, although as they were considered of vital importance for sovereignty and security, they continued to belong to the State and it reserved its rights. check.

Last but not least, it should be noted that telecommunication techniques make possible the existence of the so-called mass media —except for the notable case of the newspaper. These play a very important role in politics, as they represent a two-way link between rulers and citizens:

• They serve citizens to channel their wishes and aspirations to the ruler.
• They serve the ruler to communicate with or exercise control over citizenship.

Influence in the war

On January 8, 1815, some 8,000 British soldiers made a surprise attack on then-General Andrew Jackson's militia garrison in New Orleans during the Anglo-American War of 1812. The Battle of New Orleans resulted in a massacre for the British units due to powerful artillery fire; but more disturbing is knowing that just 15 days before peace had been signed, but the news did not cross the Atlantic until February 4 of that year.

A key factor in war is communications, and in this sense, telecommunication has become a factor of great relevance and influence; so much so that throughout history warfare has driven the development of new telecommunication techniques. In military strategy there are two key factors for managing any army: unity of action and speed of movement.

The first manifestations of remote communications in ancient history responded precisely to the warfare needs of the time, such as the use of drums, bonfires, or smoke signals. The first modern telecommunications system, Chappe's optical telegraph, it was invented in revolutionary France, besieged on all its borders; where a fast and reliable communication system became a very favorable factor in the contest. More recent is the first application of electrical telegraphy in warfare, which was carried out in the Crimean War (1853–1856); the telegraph line that was built between Baltschick and Varna, the point of operations of the Anglo-French troops destined for the Crimean peninsula. Since then, the use of the telegraph has been decisive in great conflicts such as the India Mutiny of 1857, in the that from Calcutta the bulk of the British army deployed throughout India was commanded; in the Italian unification wars in 1859, in which both the Franco-Piedmontese and the Austrian sides used the telegraph on a large scale; or in the War of Secession of the United States of 1861-1865, in which an attempt was made to use —and destroy the opponent— the technical advances of the time such as telegraphy, aerostatics, the railway or steamships; among others.

The development of telecommunications allowed in the First World War (1914-1918) the generalization of the use of telecommunications on the battlefield. Although at the beginning of the war mobile means were scarce, as it was consolidated During the war, telecommunication played an important role on the fronts, for which thousands of kilometers of telegraph and telephone lines were installed; in naval battles, in which ships communicated through wireless telegraphy; as well as in air battles and aerial reconnaissance missions, in which the use of radio stood out. In World War II (1939-1945) the use of radio broadcasting as a psychological and propaganda weapon was born, in what became to call "the struggle of ideas".

Finally, in modern warfare —from the end of World War II to the present— new war techniques of enormous importance have appeared, such as guided missiles or unmanned combat aerial vehicles; or new forms of confrontation such as electronic warfare, information warfare, information warfare, or network-focused warfare.

The influence on peace

One of the greatest consensuses regarding telecommunications refers to their potential as a key factor in achieving peace. Wherever an event of a certain gravity or urgency occurs, telecommunication systems prove to be a tool of of vital importance to minimize the effects of said event, which is why many authors agree that in telecommunication it has the capacity to be "the most efficient service to Humanity".

A recurring example of this capacity is the Molink, the «red telephone», which was a communications system that in the middle of the Cold War communicated directly with the government leadership of the United States and the Soviet Union. This telegraphic line, since it was a teletype system and not a telephone, allowed instant communication between the two powers without the possibility of misinterpretation, which compromised both parties in an almost face-to-face manner.

Economic influence

Telecommunications have been part of the economic and financial machinery since before the appearance of modern technologies, especially from the point of view of sending news that can alter the behavior of economic agents. A telecommunication is made to send certain information, and "information is power". Thus, in 1815, the influential Nathan Mayer Rothschild managed to have news of the victory at Waterloo hours before the arrival of the official news thanks to the use of pigeons. messengers, so in a speculative maneuver he sold all his state bonds and thus made believe that England had lost the war, which caused panic and the massive sale of assets, which he later bought back himself at low cost.

Investment in telecom generates split growth as the spread of telecom lowers interaction costs, expands market boundaries, and vastly expands information flows. Some modern management revolutions, such as just-in-time (JIT) production, are completely dependent on an efficient network of ubiquitous communications.

These networks are recent developments. The work of Roeller and Waverman (2001) suggests that in the OECD, the spread of modern fixed-line telecommunications networks was responsible for one third of the growth in production between 1970 and 1990. For high-income countries, mobile phones also provide significant split growth over the same time period. Sweden, for example, had an average mobile penetration rate of 64 per 100 inhabitants during the period 1996 to 2003, the highest mobile penetration observed. In the same period, Canada had an average mobile penetration rate of 26 per 100 inhabitants.

Under the same conditions, Canada is estimated to have enjoyed average GDP growth nearly 1 percent higher than it actually was, the mobile penetration rate in Canada has more than doubled.

Social influence

If in general it is considered that the three infrastructures of a society are energy, transport and communications, telecommunications are the main form of communication in today's society.
The influence of telecommunications in the social situation of people can be seen in concepts such as the knowledge society, information society or mass society, highly influential theories in the current conception of industrial and post-industrial societies of the Age Contemporary - the current one.

In the field of the mass media, the sociologist Daniel Bell argued that in history four great changes or revolutions associated with different models of society can be distinguished:

• Language: I assumed that human communities could coordinate their work to pursue a common goal.
• Writing: It allowed the administration to appear, with relevant economic records and transactions, and the transmission of knowledge—first libraries.
• The printing press: It laid the foundations of industrial society by allowing the systematization and standardization of processes, records and transactions; as well as mass education through the large strands of books, publications or newspapers.
• The telecommunications: They have allowed the so-called post-industrial society, a globalized society based on theoretical knowledge. In this society information, knowledge and creativity are the new raw materials of the economy, and the social class of the class society has ceased to be an individual's identity aspect.

Thus, already in the 1970s and 1980s, to which the theories explained here belong, it was considered that telecommunications are an essential influence for society, since it enables a direct and instantaneous dialogue capable of reaching any point the same idea, custom or mentality on the planet, conditioning social change towards a more universal and borderless conception of humanity.
This idea is also included in the concept of "global village", conceived by the Canadian Marshall McLuhan, for which, due to the expansion of the media in the 1950s, the individual would come to conceive the wide world as a small global village in which society would again behave in a much more tribal and close way. This concept has been expanded over time to include dimensions such as networks of mutual dependencies, solidarity, defense of shared ideals, such as ecology, sustainable development or democracy; a relativism, due to the lack of universal references, leaders and emerging social norms; a greater role for individuals along with social equality; or that small events that occur in certain parts of the world can have effects on a global scale: butterfly effect, chaos theory. That is, globalization.

Information and communication technologies

International cooperation in telecommunication

International cooperation in the field of telecommunications has been of vital importance to understand its history; but it was also one of the first modern forms of international organization and would mark a way of functioning that can still be seen in large international organizations such as the UN.

In the first half of the 19th century, no telecommunication crossed the borders between the different nations of the time, which were not few. Remember, for example, that the German Confederation brought together 39 different territorial entities in an area comparable to present-day Germany. In this scenario, the first international agreement was the one signed by Prussia and Austria on October 3, 1949. In this, they regulated the activity of the telegraph line between Berlin and Vienna, which ran parallel to the railway that linked them, and established the priorities of use of the line: affairs of state, train information and business correspondence -if applicable-. This agreement was followed by that of Prussia and Saxony and that of Austria and Bavaria. In 1850 these four states —Prussia, Austria, Saxony, Bavaria— formed the Austro-German Telegraph Union, which was joined by other German states and the Netherlands, and did not disappear until 1872. As major contributions of this Union, the decision in 1851 to connect the telegraph lines at the borders, dispensing with the officials who translated and repeated the messages on them; the choice of Morse's telegraph as preferred; and the decision to separate the more general and immutable agreements in an Agreement from the more technical and circumstantial ones, which were added to a Regulation annexed to the Agreement. In this way, diplomatic contacts that only modified rates or technical aspects were reduced.
The Germanic experience prospered and was a reason for imitation. After the agreements between France and Belgium (1851), France and Switzerland (1852), France and Sardinia (1853) and France and Spain (1854); these countries formed the Western European Telegraph Union, with rules very similar to the German experience. An agreement was also signed in 1852 between France, Prussia and Belgium that had the peculiarity that it recognized the right to use the international telegraph services and the secrecy of telegrams, as a precursor to the right to privacy and the secrecy of telecommunications.. This agreement was later ratified by Switzerland, Spain, Sardinia, Portugal, Turkey, Denmark, Sweden and Norway, the Papal States, Russia, the Two Sicilies and Luxembourg.
To completely unify the telegraph service in Europe, the first International Telegraph Convention was signed in Paris in 1865.

Regulation and economics of telecommunications

Telecommunications has a very specific legislative and regulatory regulation, as well as regulatory bodies that ensure compliance with said regulations, but which is also closely linked to the economic model of the sector. This is due to the fact that telecommunications were traditionally a sector monopolized by the different States, which was conceived as a public service —universal service—, but which in recent years has undergone a process of conversion to a free market with perfect competition., which has generated a transitory situation of regulated competition. In addition, the international nature of telecommunication networks makes it necessary to establish common charging and interconnection conditions.

Natural resources

A large part of communications are carried out using wireless technologies, that is, by means of electromagnetic waves that propagate throughout the environment that surrounds us. But the peculiarity is that unlike a guided medium such as a cable, in which the electromagnetic excitation is contained by the material itself and its insulation; In the case of radio communications, there is only one medium that is shared, so there is a great risk of interference between the different transmissions. For this, the administration manages the use and access to this resource, which can be considered scarce despite its large size.
Thus, limitations are established in the way in which each person or company can carry out over-the-air transmissions, even requiring some type of license or payment of fees in most cases. In fact, there are very few free access frequency bands without a license, although their distribution varies by country. Some free bands are:

From a technical point of view, what is done is to divide the transmission medium, the air, into different windows or frequency slots. In this way, these windows are distributed among the interested parties, being necessary in most cases to meet a series of requirements and the payment of certain fees. In addition, the power of the antenna used is limited so that the emission from one antenna does not interfere with those around it.

The public administration usually has a specific body, a regulatory body, which is in charge of regulating the way in which the interested agents carry out their transmissions. It also serves as an intermediary between companies that provide telecommunication services, such as Internet service providers or mobile phone operators, and their customers.

The telecommunications market

The telecommunications market is a highly specialized and modern market, due to the youth of the knowledge and technologies on which it is based. Its evolution throughout these little more than two centuries of history has been marked by the rapid growth in the number of technologies involved, services provided and users. In addition, it has evolved from a highly nationalized context and a marked character of basic infrastructure and public service, through a process of liberalization, to a free market b> but that is still regulated by the legislation of each state with the same character of public service. The United States deserves special mention, where the sector has always been supported and managed by private initiative, even going so far as to legalize monopolies in private hands.

One of the many ways the market generated by telecommunications — often called the 'big telecommunications sector' — is studied is by dividing it into the following sectors:

• Networks: The infrastructures that transport the information.
• Services: The different benefits set out in the network.
• Terminals: The equipment needed to interact with networks.
• Applications: The interface of the terminals with which the user takes advantage of the services.
• Contents: The resources to which the user can access: information, multimedia, storage...
• Industry Facilitators: Regulations, regulations, standards, etc., that condition the market.

Standardization in telecommunications

Telecommunications allows the exchange of information between different systems that typically may be based on very different technologies and even incompatible with each other. In addition, there are many manufacturers of equipment, components and instruments that compete in a common market to offer their own ideas and technologies that improve existing products and thus gain more market share. Thus, there is an obvious compatibility problem between the different systems that can be connected to each other; as well as between the products of the different manufacturers if they tried to impose their own product with their own technologies and characteristics. In current communication systems, which tend to globalize their use and extension, this discrepancy would be a major inconvenience both for the users who use telecommunication services and for the professionals who design and implement these services and the companies that provide them. these.

The normalization or standardization consists precisely in creating a set of rules that allow the industry to manufacture equipment that is compatible with each other and with the quality and safety standards demanded by both states as society. In the specific case of telecommunication, the main objective of standardization is to define how and with what 'language' to communicate. the different systems communicate. The immediate consequences of standardization, in addition to the possibility of implementing heterogeneous systems, is that the research, development and innovation of new technologies becomes a task that, although it continues to be competitive, develops in parallel and focused on one line. common development. This phenomenon causes the rate at which new technology appears to accelerate, and therefore greater obsolescence and a shorter life cycle of it; and cheaper manufacturing.

Standardization in telecommunications is closely associated with the International Organizations for Standardization:

• The International Telecommunication Union (ITU or IUT in English), which was born in 1934 as heir to the International Telegraphic Union (1865) and was integrated into the United Nations Organization in 1947. Since 1993, ITU has been organized in three main sectors:
  • ITU-R: Radiocommunications Sector (formerly IRC)
  • UTI-T: Telecommunication Standardization Sector (old ICITT)
  • UTI-D: Telecommunications Development Sector

The normalizing activity of this organism is translated into calls recommendations on telephony, telegraphy and data communication interfaces, which are then adopted by other agencies such as standardslike manufacturers or telecommunications companies. For example, some known recommendations are the V.90 that refers to the modems of 56 Kbps, the H.323 that refers to the signaling packages for the establishment of VoIP calls (voice on IP) or G.652 that specifics the characteristics of the monomode fibers.

• The International Organization for Standardization (OIS or ISO) was launched in 1948. Its members are the normalization organizations of the member countries: IRAM, AENOR, CEN... ISO issues rules on a variety of topics, such as telephone poles, quality standards, clothing manufacturing, fishing nets and many other topics. If you want to read a selection of these standards, see the ISO standards list.

• IEEE (ready i-e-cubo in Spain and i-triple-e in Hispanic America) corresponds to the acronyms of Institute of Electrical and Electronics Engineers (Instituto de Ingenieros Eléctricos y Electrónicos en castellano). IEEE has a standardization group that develops standards in the area of electrical engineering and computing, such as IEEE 802.x standards such as Ethernet, Wi-Fi, WiMAX...

Finally, it is worth mentioning other standardization groups of great importance such as the Internet Engineering Task Force (IETF) or private consortiums such as the World Wide Web Consortium (W3C). In addition, when the Internet (born from the ARPANET network of the United States) began to be developed, the members who were part of the research groups communicated through technical reports that bore the name of RFC (Request For Comments, request for comments is Spanish). These technical reports gave (and continue to give) rise to standards that are numbered according to the chronological order of creation. The RFCs establish, for example, the rules for the operation of the IP protocol, the UDP protocol, email, to name just a few examples.

Telecommunications and health

Various antennas in an urban setting.

The technologies used by telecommunications have an impact on people's health.

Evil Effects

Today, almost all telecommunications are done using electromagnetic phenomena, except those that are done by postal mail, couriers, or homing pigeons. These communications can be carried out by guided or unguided transmission means. The guided means of transmission are cables, which do not have a greater impact on health than the toxicity of their materials, for example. It is the unguided media, which use the open environment as a medium, that can report a greater risk to health.

Both electrical and magnetic energy are two manifestations of electromagnetic energy; therefore, in the same way that an electric current can be harmful to health, being immersed in an electromagnetic field can also be so; it all depends on how energetic that field is. In the specific case of telecommunications, which use forms of non-ionizing radiation, the factors that must be taken into account are the power of the antenna that generates the electromagnetic field and the distance to it. The power represents the energy emitted per unit of time, while the distance reduces the effects of the field with a square factor —as in the case of sound—, therefore, being n meters from the antenna, the field effects are reduced n² times.

In this sense, everyday technologies are assumed to be safe for the human body, as they are designed to be so. States limit the power that an antenna can emit so that it does not become harmful to health. Thus, for example, in Spain the power limitation is included in the National Frequency Allocation Table (CNAF) and the safety distance is regulated in Royal Decree 1066/2001, of September 28, which approves the Regulation that establishes conditions for the protection of the radioelectric public domain, restrictions on radioelectric emissions and health protection measures against radioelectric emissions. However, it is the long-term effects, or exposures to many electromagnetic fields of a different nature, that are the subject of study today. Certain installations are undoubtedly unsafe, such as a modulated amplitude broadcast antenna that provides radio service to an entire country or a radar station, but they are duly signposted.

Benign Effects