Contenido

Aunque como se ha visto, la «telecomunicación» como estudio unificado de las comunicaciones a distancia es una idea reciente, siempre han existido medios de comunicación que también son estudiados por esta disciplina. A lo largo de la historia han existido diferentes situaciones en las que ha sido necesaria una comunicación a distancia, como en la guerra o en el comercio.[4]​ Sin embargo, la base académica para el estudio de estos medios, como la teoría de la información, datan de mediados del siglo .

Conforme las distintas civilizaciones empezaron a extenderse por territorios cada vez mayores, fue necesario un sistema organizado de comunicaciones que permitiese el control efectivo de esos territorios.[5]​ Es probable que el método de telecomunicaciones más antiguo sea el realizado con mensajeros, personas que recorrían largas distancias con sus mensajes. Hay registros de que ya las primeras civilizaciones como la sumeria, la persa, la egipcia o la romana implementaron diversos sistemas de correo postal a lo largo de sus respectivos territorios.

Background

The first technologies used in telecommunications used visual signals such as beacons "Beacon (fire)") or smoke signals, or acoustic signals such as through the use of drums, horns "Horn (aerophone)") or bellowers.[4]​.

Thus, the Greek playwright Aeschylus (525-) relates in his work Agamemnon "Agamemnon (play)") that the eponymous character in mythology communicated to the city of Argos "Argos (Greece)"), of which he was king, and to his wife Clytemnestra, the victory of the Achaeans over Troy through a chain of fire signals that went from one point to another.[6]​[7]​ Also the Greek historian Polybius (204-) explains another example of long-distance communications, the hydraulic telegraph, which according to what he says was developed by Aeneas the Tactician in the century BC. C.[8]​[9]​ It consisted of two water tanks provided with taps and, submerged vertically, a tablet with the signs and signals that were desired to be transmitted. The sender alerted the receiver "Receiver (communication)") with torches the moment in which both should open and close the water, in such a way that the water level indicated which message on the tablet they wanted to transmit.[8]​

However, these first technical manifestations did not result in real telecommunications systems, but until the Contemporary Age, ways to carry out remote communications were not invented. It was postal mail, in its different manifestations, that assumed the role of communicating to people throughout almost all of history.[10]​.

More recent is the use of optical telegraphs, considered the first modern telecommunications system as it allows messages that had not been previously prefixed to be encoded; Until then, simple messages, such as 'danger' or 'victory', were conveyed without the possibility of giving details or descriptions. These were structures provided with mobile arms that, using ropes and pulleys, adopted different positions with which to encode the message.[11]​ Although it was Robert Hooke who, in 1684, presented the first detailed design of an optical telegraph to the Royal Society,[12]​[13]​ it was not until the beginning of the century in France when it was implemented effectively. It was during the French Revolution, when there was an important need in the country to be able to transmit orders efficiently and quickly,[13]​ when the engineer Claude Chappe and his brothers installed 556 optical telegraphs that covered a distance of almost 5000 kilometers.[11]​ The first line, with 22 towers and 230 kilometers, was laid out in 1792 between Paris and Lille,[14]​ and in 1794, transmitted the news of the French victory at Condé-sur-l'Escaut:[15]​.

The system, which turned out to be a success in the military field, spread throughout Europe although with modifications specific to each country, such as the design of Murray&action=edit&redlink=1 "Lord George Murray (bishop) (not yet written)") in Great Britain[18]​ or that of Breguet and Betancourt, as well as that of Mathé, in Spain.[19]​.

19th century. Electrical advances

Although it was in 1729 when the scientist Stephen Gray had formally discovered that electricity could be transmitted, the first technical experiments did not materialize until the 17th century, when Alessandro Volta presented to the Royal Society an instrument capable of generating direct current, the voltaic cell - see the history of electricity -. For example, an early experiment in electrical telegraphy was the electrochemical telegraph created by German scientist Samuel Thomas von Sömmerring in 1809,[note 3]​ based on a less robust 1804 design by Spanish scientist Francisco Salvá Campillo.[20]​[21]​[22]​ This invention used electrical signals that were sent along various metal cables, one for each letter. At the receiving end, the currents electrolyzed the acid in individual glass tubes, releasing streams of hydrogen bubbles in the corresponding tube to be seen by the receiver operator.[20]​[22]​.

The electric telegraph, which was developed in the first half of the century, has its origins in a multitude of experiments and new technologies, so a single inventor cannot be mentioned, although some important names can be mentioned.[23]​.

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.[24] Another example is found in the 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.[24]​.

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 was associated with the physics professor Charles Wheatstone, patented a telegraph with five electrical conductors that moved five other magnetized needles with which to point to one of the 20 letters that the device had.[25]​ In July of that same year they demonstrated their invention between the stations of Euston and Camden Town,[25]​ but it was not until July 9, 1839 when their invention began to operate between Paddington station in London and West Drayton station), 21 kilometers away.[26] 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 for each character.[26]

Finally, after managing to reduce the number of needles of their invention to just one, Cooke and Wheatstone founded the Electric Telegraph Company in 1846, precursor of the first telecommunications company - British Telecom - and by 1852 they had already installed 6,500 km of telegraph lines in England.[27] 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).[28]​.

20th century. War and electronics

At the end of the century, in the so-called Belle Époque, a feeling of optimism, enthusiasm and confidence in the future of progress and the potential of science and technology - positivism and scientism - became widespread. The rise of the bourgeoisie and the middle classes meant an emergence of people outside the aristocracy into political power, and even the proletariat felt a certain confidence in the future as the workers' struggle grew and achieved small achievements. Universal exhibitions took place, promoting a vision of global and borderless progress, and news from the outside world was spread more easily thanks to the railway, the submarine cable and the telegraph, the telecommunications system that dominated the time. It was even believed that everything had already been invented, despite the fact that the last years of the century and the first of the century were especially prolific for science and technology: the Lumière brothers projected the first cinematographic film in 1895; Medicine advanced with discoveries such as the one led by Ronald Ross, who discovered how malaria was transmitted; 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.[40]​.

Telecommunications was also nourished by the notable 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, he demonstrated that these 'Hertzian waves', as these electromagnetic phenomena were called at the time, could be reflected, refracted, polarized, diffracted and interfered with.[41]​

Many others expanded these experiments—among whom Augusto Righi stands out—[42]​ until they achieved a basis that allowed the implementation of a new telecommunications system, superior to the telegraph in efficiency and effectiveness: radiocommunication or 'wireless telegraphy'.[43]​.

The invention of radio communication, as with the telephone, is disputed between several inventors, among whom Edouard Branly, Nikola Tesla, Aleksandr Stepánovich Popov and Guillermo Marconi stand out; This article narrates the events chronologically. Furthermore, as happened with the telegraph or the telephone, 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 hit it, and which would be used by contemporary inventors to detect these waves. In fact, in France Branly is considered the inventor of radio communication.[44]​

Theoretical basis

Telecommunication 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 proceed to its implementation.

• - Mathematics: 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, calculus and differential calculus, statistics... Tools such as the Fourier transform or the Laplace transform stand out.

• - Physics: Physics provides the study of the environment that surrounds us and on which telecommunications systems are established. Electromagnetism stands out. Its mathematical basis was developed by the 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 force fields.

• - Information theory: It allows evaluating the capacity of a communication channel according to its bandwidth and its signal-to-noise ratio. It was Bell Laboratory scientist Claude E. Shannon who, with the publication in 1948 of the study titled A Mathematical Theory of Communication, formed the mathematical models used to describe communication systems.

• - Systems theory and control theory: These interdisciplinary studies allow the different telecommunications systems to be modeled"). Systems theory models the individualized contribution of each element that makes up a system while control theory models its evolution over time, which can be automatic.

• - Queuing theory: It allows modeling the quality of service with which users enjoy communication services.

• - Computing: Allows communication protocols to be programmed or simulated.

• - Electronics: Telecommunications systems are based on both analog electronic circuits and digital circuits, promoted through the massive introduction of integrated circuits, and which has made it possible to fully take advantage of the advantages of digital signal processing. Thus, for example, filters can be implemented with which to discriminate certain frequencies of a signal; This is what you do when you tune a radio or television.

Information, communication and language. Digitization

Telecommunication aims to establish communication at a distance, and all communication is associated with the delivery of certain information, since from the technical point of view to the phatic function it provides information to the message, through language.

This information is obtained from the so-called sources of information: 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 study them both in time and frequency and thus find the most efficient way to transmit them. Criteria such as signal bandwidth or transfer rate are taken into account 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.

One way to obtain this information that has taken on great importance is digitalization, 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 human speech, 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, some of the information is lost, but small enough to be negligible. Finally, in coding, each value is represented with a binary code symbol.

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

• - Issuers: it is the part of the system that encodes and emits the message. It can be an antenna, a computer, a telephone...

• - Receivers "Receiver (communication)"): is any device capable of receiving a message and extracting information from it. This is the case of a radio "Radio (receiver)"), a television...

• - Transmission medium: The physical medium through which information is transmitted, whether wired (guided medium) or wireless (unguided medium).

• - Repeaters: These are devices that amplify the signal that reaches them, so communications can be established over long distances.

• - Switches "Switch (network device)"): These are devices that route each network frame to its destination on a computer network.

• - Routers: (routers in English): These are devices that allow you to choose at any time which is the most appropriate path for network frames to reach their destination in a network with TCP/IP support.

• - Filters: Devices that allow the passage of certain signal frequencies but prevent the passage of others. They are used to tune (demultiplex) channels on a radio "Radio (receiver)") or on a television, for example.

A transmission system is modeled mathematically with 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, an entire set of components can be reduced to a single net contribution; It is then said that the output is the response of a system to an input or that the system responds to the input with a certain output. Similarly, queuing theory also takes on great relevance, since it allows us to relate 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 where it should. Furthermore, sometimes it is necessary for the system to guarantee that this information will only be received where it is intended.

• - Accuracy: The system must deliver the information accurately and without modifying it. Data that is altered in transmission must be recoverable through error detection and correcting codes or other techniques.

• - Punctuality: The system must deliver the information in the time interval provided for it. For real-time transmissions of video, audio, or voice, timely delivery means delivering data as it occurs without significant delay.

Streaming media

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, addition of noise "Noise (physics)"), distortion or delay of the signal containing the information, so each transmission medium will be suitable for a specific application.

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 magnitude. Thus, although rudimentary, the rope that joins the two ends of a "can telephone" constitutes a guided transmission medium, in this case of sound waves.

On the contrary, an unguided transmission medium is one that supports the magnitude variation to occur, but does not direct it along a specific path. This is the case, in contrast to the previous example, of sound when we talk to another person face to face.

In the current telecommunications context, most of the guided media are cables made of different metals such as copper. In the telegraph network, cables without malleable sheaths were used suspended from crossbars 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, usually plastic. The most common was telephone cable composed of two parallel copper wires, although twisted cable is currently 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.

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 in a helical manner. Since two parallel wires constitute a simple antenna; In the twisted pair, the waves of different turns cancel each other, so the radiation of the cable is less effective and allows electrical interference to be reduced, both outside and from nearby pairs. This type of cable may or may not be protected by a metal protective mesh, and may be STP (Shielded Twisted Pair, armored twisted pair*), UTP (, unshielded twisted pair) or FTP (, twisted pair covered in metal foil).

Basic communications techniques

Communications networks tend to be complex when the number of their users grows considerably, as happened at the beginning of the century with the switched telephone network. Historically, there are several objects and techniques that have allowed us to reduce the necessary network resources and increase the capacities of existing ones. In fact, the subscriber loop is usually a copper pair, which was invented at the end of the century for telephony, but which can still be used today for certain ADSL or IPTV services, technologies much more advanced than the telephone.

Through switching "Switching (communication networks)") the different nodes that exist in the network are connected, allowing the most efficient path to be chosen between the two terminals "Terminal (computing)"). 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 request of the customer. Later, automated switching systems were 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 "Modulation (telecommunication)"), which allows the information contained in an electromagnetic wave to be introduced into another called carrier wave. In this way, certain technical problems that appear when transmitting certain signals are resolved, such as those associated with the size of the antenna. This must be the size of the wavelength of the signal it radiates; By modulating the signal into 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 the distortion that the signal suffers during transmission. Modulation is the technique used in AM and FM broadcasting, for example.

Finally, through multiple media access 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 manner. For example, multiplexing divides the transmission capacity of a medium into slots or windows for each transmission. In the case of time division multiplexing, the messages are divided into segments and a time window is assigned to carry out 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 is the frequency spectrum, modulating each transmission at a different frequency so that they do not overlap, and it is recovered using an electronic filter for each frequency. It is used, for example, in FM broadcasting in which dozens of radio channels are transmitted over the air at a time but only one is heard on the receiver.

Telecommunication networks and services

A telecommunication 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, a transmission system is implemented over a set of transmission media using processing, multiplexing and modulation technologies; and transmission protocols are designed that allow establishing communication with which to carry out an effective exchange of information between users.

There are different ways to classify telecommunications networks, among which the following stand out:

In each network, which will present an appropriate topology, a distinction is usually made between the access network, in which the network terminals are located" through which the users "User (computing)" access), and the transit network or network core, where the systems necessary to establish communication and avoid the loss of information are located - the nodes of the "Node (computing)" network - and other telecommunication links.

In the simile of postal mail, postboxes and 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 its entirety.

Different functionalities are implemented on these communication networks; A telecommunication service is a set of benefits 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. Telecommunications services can be classified into:.

The traditional application of communication is voice and data transmission, as it allows two people to exchange messages almost instantly and effectively; with important applications in people's lives, in economic management, in emergencies "Emergency (disaster)") 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 carrier pigeons or semaphore messages "Semaphore (communication)").

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 users speak, and are connected through 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 circuit connection was physical, either by manual switching or by a Rotary switching system; but currently it is established digitally in digital telephone exchanges. Thus, the voice is digitized with 8 bits at about 8 kHz.

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 it can be mentioned.

• - The intranet, ATM or storage networks of private companies;

• - Academic and research networks such as GÉANT"), Internet2, RedCLARA") or the Deep Space Network; either.

• - Professional networks such as police radio, firefighters, amateurs, etc.

El desarrollo de las telecomunicaciones ha tenido lugar casi en exclusiva durante la Edad Contemporánea, y su influencia se ha dejado notar en el desarrollo de múltiples dimensiones de la actividad humana: la sociedad, la economía, la política, la paz y la guerra y, en definitiva, la historia.

La consolidación de las telecomunicaciones como una infraestructura básica las ha convertido en un factor histórico en sí mismas:.

Pero la telecomunicación excede un planteamiento meramente testimonial hasta haber conseguido eliminar casi por completo el espacio el tiempo.( 1974, p. 244).

The political influence

Telecommunications emerged as an instrument with which to centralize the power of the State and thus achieve centralized economic, military and bureaucratic management.**[60]​ In fact, the use of telecommunications within 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."[61]​.

Such is the importance of telecommunications as a key factor in the government of towns and states that telegraphic media were from their conception the object of an exclusive monopoly of the State -except in some notable cases such as the United States.[62]​ For example, France began in 1837 to punish any remote communication with signals with prison sentences or large fines; since during the June Rebellion of 1832 it was concluded that if the rebels had had access to the telegraph they would have posed a great threat.[63]​

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 take over some key structures of the State, such as telegraph and telephone exchanges, to achieve effective control.[64] Similarly, Trotsky believed that a revolutionary attack should not aim at the centers of power of the State such as the Duma, but rather at its basic infrastructures such as railways, power plants or power plants. telecommunications.[65]​ This conception of the revolution, which aims to take control of the technical infrastructures of the State, has been put into practice on various occasions: in the Coup d'état of May 1926 in Poland, or in the attempted Coup d'état of 1932 in Spain, among others.[66]​.

Over time, States allowed citizens and companies to use excess traffic in their telecommunications networks, although as they were considered of vital importance for sovereignty and security, they continued to belong to the State and it reserved its control.[67]​.

Last, but not least, it should be noted that telecommunications 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, since they represent a two-way link between rulers and citizens:

• - They serve citizens to channel their desires and aspirations to the ruler.

• - They serve the ruler to communicate with the citizens, or exercise control over them.

The influence on war

On January 8, 1815, some 8,000 British soldiers made a surprise attack on the militia garrison that then-General Andrew Jackson had in New Orleans as part of the Anglo-American War of 1812. The Battle of New Orleans resulted in a massacre for British units due to powerful artillery fire; But it is more disturbing to know that just 15 days before peace had been signed, but the news did not cross the Atlantic until February 4 of that year.[69]​.

A key factor in war is communications, and in this sense telecommunications has become a factor of great relevance and influence; so much so that throughout history wars have driven the development of new telecommunications techniques.[70]​ In military strategy there are two key factors for the management of any army: unity of action and speed of movement.[71]​.

The first manifestations of remote communications in ancient history responded precisely to the war needs of the time, such as the use of drums, bonfires or smoke signals.[72]​ The first modern telecommunications system, Chappe's optical telegraph, was invented in revolutionary France, besieged by all its borders; where a fast and reliable communications system became a very favorable factor in the war.[73]​ More recent is the first application of electric telegraphy in war, which was carried out in the Crimean War (1853–1856);[74]​ in the telegraph line that was built between Baltschick") and Varna "Varna (Bulgaria)"), point of operations for the Anglo-French troops destined for the peninsula of Crimea.[74] Since then, the use of the telegraph has been decisive in major conflicts such as the Indian Mutiny of 1857, in which the bulk of the British army deployed throughout India was commanded from Calcutta;[75] in the Italian unification wars "Unification of Italy") in 1859, in which both the Franco-Piedmontese and Austrian sides used the telegraph on a large scale. telegraph;[76]​ or in the United States Civil War 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, railroads or steamships;[31]​ among others.

The development of telecommunications allowed in the First World War (1914-1918) the generalization of the use of telecommunications on the battlefield.[77]​ Although at the beginning of the war mobile means were scarce,[78]​ as the war consolidated, telecommunications took on a relevant 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.[79]​ In the Second World War (1939-1945) the use of radio broadcasting as a psychological and propaganda weapon was born, in what came to be called "the fight of ideas."[80]​[81]​.

Finally, in modern warfare—from the end of World War II to the present day—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-centric warfare.

The influence on peace

One of the greatest consensuses regarding telecommunications refers to their potential as a key factor in achieving peace.[82]​ Where an event of a certain severity or urgency occurs, telecommunications systems prove to be a vitally important tool to minimize the effects of said event, which is why many authors agree that telecommunications has the capacity to be "the most effective service to Humanity."[82]​.

A recurring example of this capacity is Molink, the "red telephone", which was a communications system that in the middle of the Cold War directly communicated the leadership of the United States and the Soviet Union. This telegraph line, since it was a teletype system and not a telephone, allowed instant communication without the possibility of misinterpretations between the two powers, which committed both parties in an almost face-to-face manner.[83]​.

The 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 carried out to send certain information, and "information is power."[note 7]​ 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 carrier pigeons, so in a speculative maneuver "Speculation (economics)") he sold all his state bonds "Bond (finance)") and thus made it believe that England had lost the war, which caused the panic and the massive sale of assets, which he then repurchased himself at low cost.[69]​.

Investment in telecommunications generates divided growth because the spread of telecommunications reduces interaction costs, expands market boundaries, and greatly expands information flows. Some modern management revolutions, such as just-in-time (JIT) production, depend entirely 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 diffusion of modern fixed-line telecommunications networks was responsible for one-third of output growth 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 from 1996 to 2003, the highest mobile penetration observed. In that 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 almost 1 percent higher than it actually was, the mobile penetration rate in Canada has more than doubled.[84]​.

The social influence

If it is generally considered that the three infrastructures of a society are energy, transportation and communications,[85] telecommunications are the main form of communication in today's society.

The influence of telecommunications on the social situation of people can be seen in concepts such as the knowledge society, information society or mass society, very influential theories in the current conception of industrial and post-industrial societies of the Contemporary Age—the current one.

In the field of mass media, sociologist Daniel Bell maintained that in history four major changes or revolutions associated with different models of society can be distinguished:[86]​.

• - Language: It meant that human communities could coordinate their work to pursue a common goal.[87]​.

• - Writing: It allowed administration to appear, with the relevant records and economic transactions, and the transmission of knowledge - first libraries.[87]​.

• - 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 large print runs of books, publications or newspapers.[87]​.

• - Telecommunications: They have allowed the so-called post-industrial society, a globalized society based on theoretical knowledge.[note 8]​[88]​ In this society, information, knowledge and creativity are the new raw materials of the economy, and the social class of class society has ceased to be an identity aspect of the individual.[note 8]​[87]​.

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 on the planet the same idea, custom or mentality, conditioning social change towards a more universal and borderless conception of humanity.[89]​

This idea is also reflected 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 begin to conceive the wide world as a small global village in which society would once 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, .

International cooperation in the field of telecommunications has been of vital importance to understand the history of these; but it also represented 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 century no telecommunications crossed the borders between the different nations of the time, which were not few. Remember, for example, that the German Confederation grouped together 39 different territorial entities in an area comparable to today's Germany. In this scenario, the first international agreement was the one signed by Prussia and Austria on October 3, 1949. It regulated the activity of the telegraph line between Berlin and Vienna, which ran parallel to the railway that connected them, and established the priorities for the use of the line: state affairs, train information and commercial 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. The great contributions of this Union include the decision in 1851 to connect the telegraph lines at the borders, doing away with the officials who translated and repeated the messages on them; the choice of the Morse telegraph as preferred; and the decision to separate the most general and immutable agreements in a Convention from the more technical and circumstantial ones, which were added to a Regulation annexed to the Convention. In this way, diplomatic contacts that only modified rates or technical aspects were reduced.

The Germanic experience prospered and was a source of 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 Germanic experience. An agreement was also signed in 1852 between France, Prussia and Belgium which had the peculiarity that it recognized the right to use the services of the international telegraph and the secrecy of telegrams, as a precursor to the right to privacy and 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.

La telecomunicación posee una regulación legislativa y normativa muy específica, así como organismos reguladores que velan por el cumplimiento de dichas regulaciones, pero que además se haya íntimamente ligada con el modelo económico del sector. Esto se debe a que de forma tradicional las telecomunicaciones eran un sector monopolizado por los distintos Estados, que se concebía como un servicio público —servicio universal—, pero que en los últimos años está sufriendo un proceso de reconversión a un mercado libre de competencia perfecta, lo que ha generado una situación transitoria de competencia regulada. Además, el carácter internacional de las redes de telecomunicación obliga a establecer condiciones comunes de tarificación e interconexión.

natural resources

A large part of communications is carried out through wireless technologies, that is, through electromagnetic waves that propagate throughout the environment that surrounds us. But the peculiarity is that unlike a guided medium like 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. To do 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 transmissions over the air, and in most cases some type of license or the payment of fees is even necessary. In fact, there are very few frequency bands that are freely accessible 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 frequency windows or slots. In this way, these windows are distributed among the interested parties, and in most cases it is necessary to meet a series of requirements and pay 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 responsible for regulating the way in which the interested agents carry out their transmissions. It also serves as an intermediary between companies that provide telecommunications services, such as Internet service providers or mobile telephone operators, and their clients.

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. Furthermore, 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 but which continues to be 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 legalizing monopolies in private hands.

One of the many ways in which the market generated by telecommunications - often called the 'telecommunications macro sector' - is studied is by dividing it into the following sectors:[90]​.

• - Networks: The set of infrastructures that transport information.

• - Services: The different benefits that are established on the network.

• - Terminals: The equipment necessary to interact with the networks.

• - Applications: The interface of the terminals with which the user takes advantage of the services.

• - Contents: The resources that the user can access: information, multimedia, storage...

• - Industry enablers: Regulations, standards, standards, etc.; that condition the market.

Standardization in telecommunications

Telecommunications allows the exchange of information between different systems that may typically 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 achieve more market share. Thus, an obvious compatibility problem arises between the different systems that can be connected to each other; as well as between the products of different manufacturers if they try 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 very great inconvenience both for the users who use telecommunications services and for the professionals who design and implement these services and the companies that provide them.

Normalization or standardization consists precisely of creating a set of rules that allow the industry to manufacture equipment compatible with each other and with the quality and safety standards demanded by both states and society. In the specific case of telecommunications, the main objective of standardization is to define how and with what 'language' 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, which, although it remains competitive "Competition (economy)"), is developed in parallel and focused on a common line of development. This phenomenon causes the pace at which new technology appears to accelerate, and therefore greater obsolescence and a shorter life cycle; and the lowering of manufacturing costs.

Standardization in telecommunications is closely associated with International Standardization Organizations:

• - The International Telecommunications Union (ITU or IUT in English), which was born in 1934 as heir to the International Telegraph Union (1865) and in 1947 it was integrated into the United Nations Organization. Since 1993, the ITU has been organized into three main sectors:

• ITU-R: Radiocommunication Sector (former CCIR)

• ITU-T: Telecommunications Standardization Sector (former CCITT)

• ITU-D: Telecommunications Development Sector.

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

Las tecnologías de las que hace uso las telecomunicaciones tiene una incidencia en la salud de las personas.

Malignant effects

Today, almost all telecommunications are carried out using electromagnetic phenomena, except those carried out by postal mail, messengers or carrier pigeons. These communications can be carried out by guided or unguided transmission means. The guided transmission media are cables, which have no greater impact on health than the toxicity of their materials, for example. It is unguided media, which uses the open environment as a medium, that may pose a greater health risk.

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 harmful; 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 "Power (physical)") represents the energy emitted per unit of time, while distance reduces the field effects with a quadratic factor - as in the case of sound - so being n meters from the antenna, the field effects are reduced n times.

In this sense, everyday technologies are assumed to be safe for the human body, since 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) "National Frequency Allocation Table (Spain)") 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 to radioelectric emissions. However, it is the long-term effects, or exposures to many electromagnetic fields of different nature, that are the subject of study today. Certain installations are undoubtedly unsafe, such as an amplitude modulated transmitting antenna that provides radio service to an entire country or a radar station, but they are properly marked.

Benign effects

• - Annex: Chronology of communications technologies.

• - Annex: Telecommunications glossary.

• - Telecommunications engineering.

• - Electronic engineering.

• - Legal regime of the telecommunications sector (Spain) "Legal regime of the telecommunications sector (Spain)").

• - Federal Telecommunications Institute in Mexico.

• - International Telecommunications Union.

• - Machine age.

• - Fondevila Gascón, Joan Francesc (2009). The weight of television in the triple play of cable operators in Spain and Europe. ZER, Journal of Communication Studies, 14 (27), pp. 13–31. . Digital edition at the University of the Basque Country.

• - Torres, Álvaro. Telecommunications and telematics. From smoke signals to information networks and internet activities. Third edition: 2007, Colombia, Telecommunications Collection.

• - Huidobro Moya, José Manuel. Telecommunications networks and services. Madrid: Thomson, 2006.

• - Huidobro Moya, José Manuel. Telecommunications technologies. Mexico, D. F.: Alfaomega, c2006.

• - Herrera Pérez, Enrique. Introduction to modern telecommunications. Mexico: Limusa, 2004.

• - Wikinews has news related to Telecommunication.

• - International Telecommunications Union

• Multilingual terms and definitions search engine from the International Telecommunication Union.

The term "telecommunication" has its origin in the French Télécommunication, a word invented by the engineer Édouard Estaunié by adding to the Latin word communicare - to share - the Greek prefix tele-, which means distance. telephony, and published it for the first time in Traité Practique de Télécommunication Électrique (Télégraphie-Téléphonie) of 1904.[2]​.

The Castilian successfully assimilated the loan in various areas of public, academic, political and business life. Already in 1907, a "telecommunication" 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.[2] Political life also became accustomed to using the term and, in 1921, the government of Manuel Allendesalazar requested an ambitious plan to expand "Telecommunication services", which, although it never materialized due to the Annual Disaster, demonstrates the use of the term in Spanish.[2]​ In fact, at that time "telecommunication" was synonymous with modernity, which is why it was incorporated into the name of many companies of the time such as the "Iberian Telecommunication Company")" by Antonio Castilla López in 1916 or the "Company of Telecommunications and Electricity" in 1919.[2]​.

The real consolidation of the term at an international level came with the constitution of the International Telecommunications Union (ITU) at the Madrid Conference of 1932, in which "telecommunication" 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)".[2]​ The advance of telecommunications ended up making this definition outdated and, in the current Radiocommunications Regulations, the term is redefined:.

By metonymy, the study of telecommunications or telecommunications is called «Telecommunication» or «Telecommunications» interchangeably.

Contenido

Aunque como se ha visto, la «telecomunicación» como estudio unificado de las comunicaciones a distancia es una idea reciente, siempre han existido medios de comunicación que también son estudiados por esta disciplina. A lo largo de la historia han existido diferentes situaciones en las que ha sido necesaria una comunicación a distancia, como en la guerra o en el comercio.[4]​ Sin embargo, la base académica para el estudio de estos medios, como la teoría de la información, datan de mediados del siglo .

Conforme las distintas civilizaciones empezaron a extenderse por territorios cada vez mayores, fue necesario un sistema organizado de comunicaciones que permitiese el control efectivo de esos territorios.[5]​ Es probable que el método de telecomunicaciones más antiguo sea el realizado con mensajeros, personas que recorrían largas distancias con sus mensajes. Hay registros de que ya las primeras civilizaciones como la sumeria, la persa, la egipcia o la romana implementaron diversos sistemas de correo postal a lo largo de sus respectivos territorios.

Background

The first technologies used in telecommunications used visual signals such as beacons "Beacon (fire)") or smoke signals, or acoustic signals such as through the use of drums, horns "Horn (aerophone)") or bellowers.[4]​.

Thus, the Greek playwright Aeschylus (525-) relates in his work Agamemnon "Agamemnon (play)") that the eponymous character in mythology communicated to the city of Argos "Argos (Greece)"), of which he was king, and to his wife Clytemnestra, the victory of the Achaeans over Troy through a chain of fire signals that went from one point to another.[6]​[7]​ Also the Greek historian Polybius (204-) explains another example of long-distance communications, the hydraulic telegraph, which according to what he says was developed by Aeneas the Tactician in the century BC. C.[8]​[9]​ It consisted of two water tanks provided with taps and, submerged vertically, a tablet with the signs and signals that were desired to be transmitted. The sender alerted the receiver "Receiver (communication)") with torches the moment in which both should open and close the water, in such a way that the water level indicated which message on the tablet they wanted to transmit.[8]​

However, these first technical manifestations did not result in real telecommunications systems, but until the Contemporary Age, ways to carry out remote communications were not invented. It was postal mail, in its different manifestations, that assumed the role of communicating to people throughout almost all of history.[10]​.

More recent is the use of optical telegraphs, considered the first modern telecommunications system as it allows messages that had not been previously prefixed to be encoded; Until then, simple messages, such as 'danger' or 'victory', were conveyed without the possibility of giving details or descriptions. These were structures provided with mobile arms that, using ropes and pulleys, adopted different positions with which to encode the message.[11]​ Although it was Robert Hooke who, in 1684, presented the first detailed design of an optical telegraph to the Royal Society,[12]​[13]​ it was not until the beginning of the century in France when it was implemented effectively. It was during the French Revolution, when there was an important need in the country to be able to transmit orders efficiently and quickly,[13]​ when the engineer Claude Chappe and his brothers installed 556 optical telegraphs that covered a distance of almost 5000 kilometers.[11]​ The first line, with 22 towers and 230 kilometers, was laid out in 1792 between Paris and Lille,[14]​ and in 1794, transmitted the news of the French victory at Condé-sur-l'Escaut:[15]​.

The system, which turned out to be a success in the military field, spread throughout Europe although with modifications specific to each country, such as the design of Murray&action=edit&redlink=1 "Lord George Murray (bishop) (not yet written)") in Great Britain[18]​ or that of Breguet and Betancourt, as well as that of Mathé, in Spain.[19]​.

19th century. Electrical advances

Although it was in 1729 when the scientist Stephen Gray had formally discovered that electricity could be transmitted, the first technical experiments did not materialize until the 17th century, when Alessandro Volta presented to the Royal Society an instrument capable of generating direct current, the voltaic cell - see the history of electricity -. For example, an early experiment in electrical telegraphy was the electrochemical telegraph created by German scientist Samuel Thomas von Sömmerring in 1809,[note 3]​ based on a less robust 1804 design by Spanish scientist Francisco Salvá Campillo.[20]​[21]​[22]​ This invention used electrical signals that were sent along various metal cables, one for each letter. At the receiving end, the currents electrolyzed the acid in individual glass tubes, releasing streams of hydrogen bubbles in the corresponding tube to be seen by the receiver operator.[20]​[22]​.

The electric telegraph, which was developed in the first half of the century, has its origins in a multitude of experiments and new technologies, so a single inventor cannot be mentioned, although some important names can be mentioned.[23]​.

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.[24] Another example is found in the 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.[24]​.

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 was associated with the physics professor Charles Wheatstone, patented a telegraph with five electrical conductors that moved five other magnetized needles with which to point to one of the 20 letters that the device had.[25]​ In July of that same year they demonstrated their invention between the stations of Euston and Camden Town,[25]​ but it was not until July 9, 1839 when their invention began to operate between Paddington station in London and West Drayton station), 21 kilometers away.[26] 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 for each character.[26]

Finally, after managing to reduce the number of needles of their invention to just one, Cooke and Wheatstone founded the Electric Telegraph Company in 1846, precursor of the first telecommunications company - British Telecom - and by 1852 they had already installed 6,500 km of telegraph lines in England.[27] 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).[28]​.

20th century. War and electronics

At the end of the century, in the so-called Belle Époque, a feeling of optimism, enthusiasm and confidence in the future of progress and the potential of science and technology - positivism and scientism - became widespread. The rise of the bourgeoisie and the middle classes meant an emergence of people outside the aristocracy into political power, and even the proletariat felt a certain confidence in the future as the workers' struggle grew and achieved small achievements. Universal exhibitions took place, promoting a vision of global and borderless progress, and news from the outside world was spread more easily thanks to the railway, the submarine cable and the telegraph, the telecommunications system that dominated the time. It was even believed that everything had already been invented, despite the fact that the last years of the century and the first of the century were especially prolific for science and technology: the Lumière brothers projected the first cinematographic film in 1895; Medicine advanced with discoveries such as the one led by Ronald Ross, who discovered how malaria was transmitted; 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.[40]​.

Telecommunications was also nourished by the notable 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, he demonstrated that these 'Hertzian waves', as these electromagnetic phenomena were called at the time, could be reflected, refracted, polarized, diffracted and interfered with.[41]​

Many others expanded these experiments—among whom Augusto Righi stands out—[42]​ until they achieved a basis that allowed the implementation of a new telecommunications system, superior to the telegraph in efficiency and effectiveness: radiocommunication or 'wireless telegraphy'.[43]​.

The invention of radio communication, as with the telephone, is disputed between several inventors, among whom Edouard Branly, Nikola Tesla, Aleksandr Stepánovich Popov and Guillermo Marconi stand out; This article narrates the events chronologically. Furthermore, as happened with the telegraph or the telephone, 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 hit it, and which would be used by contemporary inventors to detect these waves. In fact, in France Branly is considered the inventor of radio communication.[44]​

Theoretical basis

Telecommunication 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 proceed to its implementation.

• - Mathematics: 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, calculus and differential calculus, statistics... Tools such as the Fourier transform or the Laplace transform stand out.

• - Physics: Physics provides the study of the environment that surrounds us and on which telecommunications systems are established. Electromagnetism stands out. Its mathematical basis was developed by the 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 force fields.

• - Information theory: It allows evaluating the capacity of a communication channel according to its bandwidth and its signal-to-noise ratio. It was Bell Laboratory scientist Claude E. Shannon who, with the publication in 1948 of the study titled A Mathematical Theory of Communication, formed the mathematical models used to describe communication systems.

• - Systems theory and control theory: These interdisciplinary studies allow the different telecommunications systems to be modeled"). Systems theory models the individualized contribution of each element that makes up a system while control theory models its evolution over time, which can be automatic.

• - Queuing theory: It allows modeling the quality of service with which users enjoy communication services.

• - Computing: Allows communication protocols to be programmed or simulated.

• - Electronics: Telecommunications systems are based on both analog electronic circuits and digital circuits, promoted through the massive introduction of integrated circuits, and which has made it possible to fully take advantage of the advantages of digital signal processing. Thus, for example, filters can be implemented with which to discriminate certain frequencies of a signal; This is what you do when you tune a radio or television.

Information, communication and language. Digitization

Telecommunication aims to establish communication at a distance, and all communication is associated with the delivery of certain information, since from the technical point of view to the phatic function it provides information to the message, through language.

This information is obtained from the so-called sources of information: 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 study them both in time and frequency and thus find the most efficient way to transmit them. Criteria such as signal bandwidth or transfer rate are taken into account 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.

One way to obtain this information that has taken on great importance is digitalization, 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 human speech, 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, some of the information is lost, but small enough to be negligible. Finally, in coding, each value is represented with a binary code symbol.

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

• - Issuers: it is the part of the system that encodes and emits the message. It can be an antenna, a computer, a telephone...

• - Receivers "Receiver (communication)"): is any device capable of receiving a message and extracting information from it. This is the case of a radio "Radio (receiver)"), a television...

• - Transmission medium: The physical medium through which information is transmitted, whether wired (guided medium) or wireless (unguided medium).

• - Repeaters: These are devices that amplify the signal that reaches them, so communications can be established over long distances.

• - Switches "Switch (network device)"): These are devices that route each network frame to its destination on a computer network.

• - Routers: (routers in English): These are devices that allow you to choose at any time which is the most appropriate path for network frames to reach their destination in a network with TCP/IP support.

• - Filters: Devices that allow the passage of certain signal frequencies but prevent the passage of others. They are used to tune (demultiplex) channels on a radio "Radio (receiver)") or on a television, for example.

A transmission system is modeled mathematically with 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, an entire set of components can be reduced to a single net contribution; It is then said that the output is the response of a system to an input or that the system responds to the input with a certain output. Similarly, queuing theory also takes on great relevance, since it allows us to relate 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 where it should. Furthermore, sometimes it is necessary for the system to guarantee that this information will only be received where it is intended.

• - Accuracy: The system must deliver the information accurately and without modifying it. Data that is altered in transmission must be recoverable through error detection and correcting codes or other techniques.

• - Punctuality: The system must deliver the information in the time interval provided for it. For real-time transmissions of video, audio, or voice, timely delivery means delivering data as it occurs without significant delay.

Streaming media

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, addition of noise "Noise (physics)"), distortion or delay of the signal containing the information, so each transmission medium will be suitable for a specific application.

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 magnitude. Thus, although rudimentary, the rope that joins the two ends of a "can telephone" constitutes a guided transmission medium, in this case of sound waves.

On the contrary, an unguided transmission medium is one that supports the magnitude variation to occur, but does not direct it along a specific path. This is the case, in contrast to the previous example, of sound when we talk to another person face to face.

In the current telecommunications context, most of the guided media are cables made of different metals such as copper. In the telegraph network, cables without malleable sheaths were used suspended from crossbars 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, usually plastic. The most common was telephone cable composed of two parallel copper wires, although twisted cable is currently 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.

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 in a helical manner. Since two parallel wires constitute a simple antenna; In the twisted pair, the waves of different turns cancel each other, so the radiation of the cable is less effective and allows electrical interference to be reduced, both outside and from nearby pairs. This type of cable may or may not be protected by a metal protective mesh, and may be STP (Shielded Twisted Pair, armored twisted pair*), UTP (, unshielded twisted pair) or FTP (, twisted pair covered in metal foil).

Basic communications techniques

Communications networks tend to be complex when the number of their users grows considerably, as happened at the beginning of the century with the switched telephone network. Historically, there are several objects and techniques that have allowed us to reduce the necessary network resources and increase the capacities of existing ones. In fact, the subscriber loop is usually a copper pair, which was invented at the end of the century for telephony, but which can still be used today for certain ADSL or IPTV services, technologies much more advanced than the telephone.

Through switching "Switching (communication networks)") the different nodes that exist in the network are connected, allowing the most efficient path to be chosen between the two terminals "Terminal (computing)"). 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 request of the customer. Later, automated switching systems were 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 "Modulation (telecommunication)"), which allows the information contained in an electromagnetic wave to be introduced into another called carrier wave. In this way, certain technical problems that appear when transmitting certain signals are resolved, such as those associated with the size of the antenna. This must be the size of the wavelength of the signal it radiates; By modulating the signal into 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 the distortion that the signal suffers during transmission. Modulation is the technique used in AM and FM broadcasting, for example.

Finally, through multiple media access 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 manner. For example, multiplexing divides the transmission capacity of a medium into slots or windows for each transmission. In the case of time division multiplexing, the messages are divided into segments and a time window is assigned to carry out 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 is the frequency spectrum, modulating each transmission at a different frequency so that they do not overlap, and it is recovered using an electronic filter for each frequency. It is used, for example, in FM broadcasting in which dozens of radio channels are transmitted over the air at a time but only one is heard on the receiver.

Telecommunication networks and services

A telecommunication 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, a transmission system is implemented over a set of transmission media using processing, multiplexing and modulation technologies; and transmission protocols are designed that allow establishing communication with which to carry out an effective exchange of information between users.

There are different ways to classify telecommunications networks, among which the following stand out:

In each network, which will present an appropriate topology, a distinction is usually made between the access network, in which the network terminals are located" through which the users "User (computing)" access), and the transit network or network core, where the systems necessary to establish communication and avoid the loss of information are located - the nodes of the "Node (computing)" network - and other telecommunication links.

In the simile of postal mail, postboxes and 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 its entirety.

Different functionalities are implemented on these communication networks; A telecommunication service is a set of benefits 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. Telecommunications services can be classified into:.

The traditional application of communication is voice and data transmission, as it allows two people to exchange messages almost instantly and effectively; with important applications in people's lives, in economic management, in emergencies "Emergency (disaster)") 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 carrier pigeons or semaphore messages "Semaphore (communication)").

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 users speak, and are connected through 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 circuit connection was physical, either by manual switching or by a Rotary switching system; but currently it is established digitally in digital telephone exchanges. Thus, the voice is digitized with 8 bits at about 8 kHz.

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 it can be mentioned.

• - The intranet, ATM or storage networks of private companies;

• - Academic and research networks such as GÉANT"), Internet2, RedCLARA") or the Deep Space Network; either.

• - Professional networks such as police radio, firefighters, amateurs, etc.

El desarrollo de las telecomunicaciones ha tenido lugar casi en exclusiva durante la Edad Contemporánea, y su influencia se ha dejado notar en el desarrollo de múltiples dimensiones de la actividad humana: la sociedad, la economía, la política, la paz y la guerra y, en definitiva, la historia.

La consolidación de las telecomunicaciones como una infraestructura básica las ha convertido en un factor histórico en sí mismas:.

Pero la telecomunicación excede un planteamiento meramente testimonial hasta haber conseguido eliminar casi por completo el espacio el tiempo.( 1974, p. 244).

The political influence

Telecommunications emerged as an instrument with which to centralize the power of the State and thus achieve centralized economic, military and bureaucratic management.**[60]​ In fact, the use of telecommunications within 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."[61]​.

Such is the importance of telecommunications as a key factor in the government of towns and states that telegraphic media were from their conception the object of an exclusive monopoly of the State -except in some notable cases such as the United States.[62]​ For example, France began in 1837 to punish any remote communication with signals with prison sentences or large fines; since during the June Rebellion of 1832 it was concluded that if the rebels had had access to the telegraph they would have posed a great threat.[63]​

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 take over some key structures of the State, such as telegraph and telephone exchanges, to achieve effective control.[64] Similarly, Trotsky believed that a revolutionary attack should not aim at the centers of power of the State such as the Duma, but rather at its basic infrastructures such as railways, power plants or power plants. telecommunications.[65]​ This conception of the revolution, which aims to take control of the technical infrastructures of the State, has been put into practice on various occasions: in the Coup d'état of May 1926 in Poland, or in the attempted Coup d'état of 1932 in Spain, among others.[66]​.

Over time, States allowed citizens and companies to use excess traffic in their telecommunications networks, although as they were considered of vital importance for sovereignty and security, they continued to belong to the State and it reserved its control.[67]​.

Last, but not least, it should be noted that telecommunications 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, since they represent a two-way link between rulers and citizens:

• - They serve citizens to channel their desires and aspirations to the ruler.

• - They serve the ruler to communicate with the citizens, or exercise control over them.

The influence on war

On January 8, 1815, some 8,000 British soldiers made a surprise attack on the militia garrison that then-General Andrew Jackson had in New Orleans as part of the Anglo-American War of 1812. The Battle of New Orleans resulted in a massacre for British units due to powerful artillery fire; But it is more disturbing to know that just 15 days before peace had been signed, but the news did not cross the Atlantic until February 4 of that year.[69]​.

A key factor in war is communications, and in this sense telecommunications has become a factor of great relevance and influence; so much so that throughout history wars have driven the development of new telecommunications techniques.[70]​ In military strategy there are two key factors for the management of any army: unity of action and speed of movement.[71]​.

The first manifestations of remote communications in ancient history responded precisely to the war needs of the time, such as the use of drums, bonfires or smoke signals.[72]​ The first modern telecommunications system, Chappe's optical telegraph, was invented in revolutionary France, besieged by all its borders; where a fast and reliable communications system became a very favorable factor in the war.[73]​ More recent is the first application of electric telegraphy in war, which was carried out in the Crimean War (1853–1856);[74]​ in the telegraph line that was built between Baltschick") and Varna "Varna (Bulgaria)"), point of operations for the Anglo-French troops destined for the peninsula of Crimea.[74] Since then, the use of the telegraph has been decisive in major conflicts such as the Indian Mutiny of 1857, in which the bulk of the British army deployed throughout India was commanded from Calcutta;[75] in the Italian unification wars "Unification of Italy") in 1859, in which both the Franco-Piedmontese and Austrian sides used the telegraph on a large scale. telegraph;[76]​ or in the United States Civil War 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, railroads or steamships;[31]​ among others.

The development of telecommunications allowed in the First World War (1914-1918) the generalization of the use of telecommunications on the battlefield.[77]​ Although at the beginning of the war mobile means were scarce,[78]​ as the war consolidated, telecommunications took on a relevant 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.[79]​ In the Second World War (1939-1945) the use of radio broadcasting as a psychological and propaganda weapon was born, in what came to be called "the fight of ideas."[80]​[81]​.

Finally, in modern warfare—from the end of World War II to the present day—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-centric warfare.

The influence on peace

One of the greatest consensuses regarding telecommunications refers to their potential as a key factor in achieving peace.[82]​ Where an event of a certain severity or urgency occurs, telecommunications systems prove to be a vitally important tool to minimize the effects of said event, which is why many authors agree that telecommunications has the capacity to be "the most effective service to Humanity."[82]​.

A recurring example of this capacity is Molink, the "red telephone", which was a communications system that in the middle of the Cold War directly communicated the leadership of the United States and the Soviet Union. This telegraph line, since it was a teletype system and not a telephone, allowed instant communication without the possibility of misinterpretations between the two powers, which committed both parties in an almost face-to-face manner.[83]​.

The 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 carried out to send certain information, and "information is power."[note 7]​ 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 carrier pigeons, so in a speculative maneuver "Speculation (economics)") he sold all his state bonds "Bond (finance)") and thus made it believe that England had lost the war, which caused the panic and the massive sale of assets, which he then repurchased himself at low cost.[69]​.

Investment in telecommunications generates divided growth because the spread of telecommunications reduces interaction costs, expands market boundaries, and greatly expands information flows. Some modern management revolutions, such as just-in-time (JIT) production, depend entirely 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 diffusion of modern fixed-line telecommunications networks was responsible for one-third of output growth 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 from 1996 to 2003, the highest mobile penetration observed. In that 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 almost 1 percent higher than it actually was, the mobile penetration rate in Canada has more than doubled.[84]​.

The social influence

If it is generally considered that the three infrastructures of a society are energy, transportation and communications,[85] telecommunications are the main form of communication in today's society.

The influence of telecommunications on the social situation of people can be seen in concepts such as the knowledge society, information society or mass society, very influential theories in the current conception of industrial and post-industrial societies of the Contemporary Age—the current one.

In the field of mass media, sociologist Daniel Bell maintained that in history four major changes or revolutions associated with different models of society can be distinguished:[86]​.

• - Language: It meant that human communities could coordinate their work to pursue a common goal.[87]​.

• - Writing: It allowed administration to appear, with the relevant records and economic transactions, and the transmission of knowledge - first libraries.[87]​.

• - 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 large print runs of books, publications or newspapers.[87]​.

• - Telecommunications: They have allowed the so-called post-industrial society, a globalized society based on theoretical knowledge.[note 8]​[88]​ In this society, information, knowledge and creativity are the new raw materials of the economy, and the social class of class society has ceased to be an identity aspect of the individual.[note 8]​[87]​.

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 on the planet the same idea, custom or mentality, conditioning social change towards a more universal and borderless conception of humanity.[89]​

This idea is also reflected 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 begin to conceive the wide world as a small global village in which society would once 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, .

International cooperation in the field of telecommunications has been of vital importance to understand the history of these; but it also represented 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 century no telecommunications crossed the borders between the different nations of the time, which were not few. Remember, for example, that the German Confederation grouped together 39 different territorial entities in an area comparable to today's Germany. In this scenario, the first international agreement was the one signed by Prussia and Austria on October 3, 1949. It regulated the activity of the telegraph line between Berlin and Vienna, which ran parallel to the railway that connected them, and established the priorities for the use of the line: state affairs, train information and commercial 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. The great contributions of this Union include the decision in 1851 to connect the telegraph lines at the borders, doing away with the officials who translated and repeated the messages on them; the choice of the Morse telegraph as preferred; and the decision to separate the most general and immutable agreements in a Convention from the more technical and circumstantial ones, which were added to a Regulation annexed to the Convention. In this way, diplomatic contacts that only modified rates or technical aspects were reduced.

The Germanic experience prospered and was a source of 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 Germanic experience. An agreement was also signed in 1852 between France, Prussia and Belgium which had the peculiarity that it recognized the right to use the services of the international telegraph and the secrecy of telegrams, as a precursor to the right to privacy and 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.

La telecomunicación posee una regulación legislativa y normativa muy específica, así como organismos reguladores que velan por el cumplimiento de dichas regulaciones, pero que además se haya íntimamente ligada con el modelo económico del sector. Esto se debe a que de forma tradicional las telecomunicaciones eran un sector monopolizado por los distintos Estados, que se concebía como un servicio público —servicio universal—, pero que en los últimos años está sufriendo un proceso de reconversión a un mercado libre de competencia perfecta, lo que ha generado una situación transitoria de competencia regulada. Además, el carácter internacional de las redes de telecomunicación obliga a establecer condiciones comunes de tarificación e interconexión.

natural resources

A large part of communications is carried out through wireless technologies, that is, through electromagnetic waves that propagate throughout the environment that surrounds us. But the peculiarity is that unlike a guided medium like 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. To do 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 transmissions over the air, and in most cases some type of license or the payment of fees is even necessary. In fact, there are very few frequency bands that are freely accessible 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 frequency windows or slots. In this way, these windows are distributed among the interested parties, and in most cases it is necessary to meet a series of requirements and pay 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 responsible for regulating the way in which the interested agents carry out their transmissions. It also serves as an intermediary between companies that provide telecommunications services, such as Internet service providers or mobile telephone operators, and their clients.

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. Furthermore, 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 but which continues to be 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 legalizing monopolies in private hands.

One of the many ways in which the market generated by telecommunications - often called the 'telecommunications macro sector' - is studied is by dividing it into the following sectors:[90]​.

• - Networks: The set of infrastructures that transport information.

• - Services: The different benefits that are established on the network.

• - Terminals: The equipment necessary to interact with the networks.

• - Applications: The interface of the terminals with which the user takes advantage of the services.

• - Contents: The resources that the user can access: information, multimedia, storage...

• - Industry enablers: Regulations, standards, standards, etc.; that condition the market.

Standardization in telecommunications

Telecommunications allows the exchange of information between different systems that may typically 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 achieve more market share. Thus, an obvious compatibility problem arises between the different systems that can be connected to each other; as well as between the products of different manufacturers if they try 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 very great inconvenience both for the users who use telecommunications services and for the professionals who design and implement these services and the companies that provide them.

Normalization or standardization consists precisely of creating a set of rules that allow the industry to manufacture equipment compatible with each other and with the quality and safety standards demanded by both states and society. In the specific case of telecommunications, the main objective of standardization is to define how and with what 'language' 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, which, although it remains competitive "Competition (economy)"), is developed in parallel and focused on a common line of development. This phenomenon causes the pace at which new technology appears to accelerate, and therefore greater obsolescence and a shorter life cycle; and the lowering of manufacturing costs.

Standardization in telecommunications is closely associated with International Standardization Organizations:

• - The International Telecommunications Union (ITU or IUT in English), which was born in 1934 as heir to the International Telegraph Union (1865) and in 1947 it was integrated into the United Nations Organization. Since 1993, the ITU has been organized into three main sectors:

• ITU-R: Radiocommunication Sector (former CCIR)

• ITU-T: Telecommunications Standardization Sector (former CCITT)

• ITU-D: Telecommunications Development Sector.

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

Las tecnologías de las que hace uso las telecomunicaciones tiene una incidencia en la salud de las personas.

Malignant effects

Today, almost all telecommunications are carried out using electromagnetic phenomena, except those carried out by postal mail, messengers or carrier pigeons. These communications can be carried out by guided or unguided transmission means. The guided transmission media are cables, which have no greater impact on health than the toxicity of their materials, for example. It is unguided media, which uses the open environment as a medium, that may pose a greater health risk.

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 harmful; 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 "Power (physical)") represents the energy emitted per unit of time, while distance reduces the field effects with a quadratic factor - as in the case of sound - so being n meters from the antenna, the field effects are reduced n times.

In this sense, everyday technologies are assumed to be safe for the human body, since 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) "National Frequency Allocation Table (Spain)") 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 to radioelectric emissions. However, it is the long-term effects, or exposures to many electromagnetic fields of different nature, that are the subject of study today. Certain installations are undoubtedly unsafe, such as an amplitude modulated transmitting antenna that provides radio service to an entire country or a radar station, but they are properly marked.

Benign effects

• - Annex: Chronology of communications technologies.

• - Annex: Telecommunications glossary.

• - Telecommunications engineering.

• - Electronic engineering.

• - Legal regime of the telecommunications sector (Spain) "Legal regime of the telecommunications sector (Spain)").

• - Federal Telecommunications Institute in Mexico.

• - International Telecommunications Union.

• - Machine age.

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• - Wikinews has news related to Telecommunication.

• - International Telecommunications Union

• Multilingual terms and definitions search engine from the International Telecommunication Union.