450 g. BC e.- the ancient Greek philosophers Democritus and Cleoxenus proposed to create an optical torch telegraph.

1600 g. - the book of the English scientist Gilbert "On a magnet, magnetic bodies and a large magnet - the Earth." It described the already known properties of the magnet, as well as the author's own discoveries.

1663. – The German scientist Otto von Guericke conducted experimental work to determine the phenomenon of electrostatic repulsion of unipolarly charged objects.

1729. - Englishman Gray discovered the phenomenon of electrical conductivity.

1745. – The German physicist Ewald Jurgen von Kleist and the Dutch physicist Peter van Muschenbroek created the Leyden jar, the first capacitor.

1753. — Leipzig physicist Winkler discovered a way to transmit electric current through wires.

1761. – one of the greatest mathematicians, St. Petersburg academician Leonhard Euler, for the first time expressed the idea of transmitting information with the help of ether vibrations.

1780. - Galvani discovered the first design of the detector, not artificial, but natural - biological.

1785. – French physicist Charles Coulomb, the founder of electrostatics, found that the force of interaction of electric charges is proportional to their magnitudes and inversely proportional to the square of the distance between them.

1793. - K. Stapp invented the "optical telegraph".

1794. - the first line of the "optical telegraph" was put into operation, built between Lille and Paris (about 250 km), which had 22 intermediate (relay) stations.

1800. - Volta invented a galvanic cell - the so-called "Voltaic column", which became the first source of direct current.

1820. Oerstedt discovered the connection between electric current and magnetic field. Electric current generates a magnetic field.

1820. -A. M. Ampere discovered the interaction of electric currents and established the law of this interaction (Ampère's law).

1832. - Pavel Lvovich Schilling invented the pointer telegraph apparatus, in which five arrows served as indicators.

1837. - American scientist C. Page created the so-called "grunting wire".

1838– The German scientist K. A. Shteingel invented the so-called grounding.

1838. – S. Morse invented the original non-uniform code.

1839. - the longest "optical telegraph" line in the world at that time was built between St. Petersburg and Warsaw (1200 km).

1841. - under the leadership of Jacobi, the first telegraph line was built between the Winter Palace and the General Staff.

1844. - under the leadership of Morse, a telegraph line was built between Washington and Baltimore with a total length of 65 km.

1850. – B.S. Jacobi developed the world's first telegraph apparatus (three years earlier than Morse) with direct printing of received messages, in which, as he said, "the registration of characters was carried out using a typographic font."

1851. - Morse code has been slightly modified and recognized as an international code.

1855.– French telegraph mechanic E. Baudot invented the first telegraph printing machine.

1858. - Winston invented an apparatus that outputs information directly to a telegraph tape built into it (a prototype of a modern telegraph apparatus).

1860. - a physics teacher at the school of Friedrichsdorf (Germany) Philipp Reiss from improvised means (a cork from a barrel, a knitting needle, an old broken violin, a coil of insulated wire and a galvanic cell) created an apparatus for demonstrating the principle of the ear.

1868. -Mahlon Loomis demonstrated to a group of US congressmen and scientists the operation of a prototype 22 km wireless link.

1869. - Professor of Kharkov University Yu. I. Morozov developed a transmitter - a prototype of a microphone.

July 30, 1872– M. Loomis was issued the world's first patent (No. 129971) for a wireless telegraph system.

1872. - Russian engineer A.N. Lodygin invented the first electric incandescent lighting lamp, which opened the era of electrovacuum technology.

1873. - English physicist W. Crookes invented a device - "radiometer".

1873. -Maxwell combined all his works in "The Doctrine of Electricity and Magnetism".

1874. – Bodo created a multiple printing cabling system.

1877 d. - D. E. Hughes designed a telephone transmitter, which he called a microphone.

1877. - in the USA, according to the project of the Hungarian engineer T. Puskas, the first telephone exchange was built.

1878. – Stewart came to the conclusion that in the Earth's atmosphere there is an ionized region of the ionosphere - a conductive layer of the atmosphere, i.e. the Earth and the ionosphere are capacitor plates.

1879. – Russian scientist Michalsky was the first in the world to use charcoal powder in a microphone. This principle has been used to this day.

1882.– P. M. Golubitsky invented a highly sensitive telephone and designed a desktop telephone with a lever for automatic circuit switching by changing the position of the handset.

1883. Edison discovered the effect of spraying the substance of an incandescent filament in an electric lamp.

1883. - P. M. Golubitsky created a telephone with two poles located eccentrically relative to the center of the membrane, which still works today.

1883. -P. M. Golubitsky designed a microphone with carbon powder.

1886. – G. Hertz invented a method for detecting electromagnetic waves.

1887. - Russian inventor K. A. Mosnitsky created a “self-acting central switch” - the forerunner of automatic telephone exchanges (ATS).

1887. - the famous experiments of Heinrich Hertz were carried out, which proved the reality of radio waves, the existence of which followed from the theory of J.K. Maxwell.

1889. - American inventor A. G. Stranger received a patent for an automatic telephone exchange.

1890. - the famous French physicist E. Branly invented a device capable of responding to electromagnetic radiation in the radio range. The detector in the receiver was a coherer.

1893. - Russian inventors M. F. Freidenberg and S. M. Berdichevsky - Apostolov proposed their "telephone connector" - automatic telephone exchange with stepper finders.

1895. – M. F. Freidenberg patented one of the most important nodes of decade-step exchanges - a pre-selector (a device for automatically searching for a called subscriber).

1896. – Freidenberg M. F. created a machine searcher with reverse control from the register installed in the subscriber's device.

April 25 (May 7), 1895. - the first public demonstration of a radio link by A. S. Popov. This day in our country is annually celebrated as Radio Day.

March 24 (12), 1896- with the help of A. S. Popov's equipment, the world's first text radiogram was transmitted, which was recorded on a telegraph tape.

1896. Freidenberg patented the machine-type finder.

1896. - Berdichevsky - Apostolov created the original automatic telephone exchange system for 11 thousand numbers.

1898. – Between Moscow and St. Petersburg, the world's longest air telephone line (660 km) was built.

May 1899. – For the first time in a sound form, broadcast telegrams were listened to on the head telephone in Russia by A. S. Popov’s assistants P. N. Rybkin and A. S. Troitsky.

1899. – A. S. Popov was the first to use radio communications to save the ship and people. The communication range exceeded 40 km.

1900. - the beginning of the radio armament of the ships of the Russian navy, i.e. the practical and regular use of radio communications in military affairs.

August 24, 1900- Russian scientist Konstantin Dmitrievich Persky introduced the concept of television "television".

1904. Fleming, an Englishman, invented the tube diode.

1906. - American Lee de Forest invented a lamp with a control electrode - a three-electrode lamp that provides the possibility of amplifying alternating currents.

July 25, 1907. - B. L. Rosing received "Privilege No. 18076" for a receiving tube for "electric telescope". Tubes designed to receive images were later called kinescopes.

1912. - V. I. Kovalenkov developed a generator lamp with an external anode cooled by water.

1913. – Meisner discovered the possibility of self-excitation of oscillations in a circuit containing an electron tube and an oscillatory circuit.

1915. – Russian engineer B. I. Kovalenkov developed and applied the first duplex telephone broadcast on triodes.

1918. – E. Armstrong invented the superheterodyne receiver.

1919. – Schottky invented the tetrode, which found practical application only in 1924-1929.

1922. – O. V. Losev discovered the effect of amplification and generation of high-frequency oscillations with the help of crystals.

1922. - radio amateurs discovered the property of short waves to propagate to any distance due to refraction in the upper atmosphere and reflection from them.

1923. -Soviet scientist Losev O. V. for the first time observed the glow of a semiconductor (silicon carbide) diode when an electric current was passed through it.

March 1929 The first regular broadcasts began in Germany.

1930s- meter waves were mastered, propagating in a straight line, without bending around the earth's surface (i.e., within the line of sight).

1930. - Based on the work of Langmuir, pentodes appeared.

April 29 and May 2, 1931- the first broadcasts of television images by radio were made in the USSR. They were implemented with the decomposition of the image into 30 lines.

August 1931– German scientist Manfred von Ardenne was the first in the world to publicly demonstrate a fully electronic television system based on a traveling beam sensor with a scan of 90 lines.

September 24, 1931– Soviet scientist S. I. Kataev received priority for the invention of a transmitting tube with charge filling, a mosaic target and switching using secondary electrons.

1934. – E. Armstrong invented frequency modulation (FM).

1936. - Soviet scientists P. V. Timofeev and P. V. Shmakov issued a certificate of authorship for a cathode ray tube with image transfer.

1938. - in the USSR, the first experimental television centers were put into operation in Moscow and Leningrad. The resolution of the transmitted image in Moscow was 343 lines, and in Leningrad - 240 lines at 25 frames per second. On July 25, 1940, the 441-line expansion standard was approved.

1938. - In the USSR, serial production of console receivers for 343 lines of the TK-1 type with a screen size of 14 × 18 cm began.

1939. - E. Armstrong built the first radio station operating in the VHF band of radio waves.

1940s– mastered decimeter and centimeter waves.

1948. - American researchers led by Shockley invented a semiconductor triode-transistor.

1949. - in the USSR, serial production of KVN-49 TVs on a tube with a diameter of 17 cm began (developers V.K. Kenigson, N.M. Varshavsky, N.A. Nikolaevsky).

March 4, 1950– The first research center for the receiving television network has been established in Moscow.

1953 –1954- In the USSR, the first domestic equipment for radio relay communication of the meter range "Crab" was developed. It was used on the communication line between Krasnovodsk and Baku across the Caspian Sea.

Mid 50s– In the USSR, a family of radio-relay equipment "Strela" was developed.

October 4, 1957- The first Soviet artificial Earth satellite (AES) was launched into orbit, the era of space communications began.

1958. – On the basis of the R-600 operating in the 4 GHz band, the first main radio relay line Leningrad-Tallinn was put into operation.

1960. - The first transmission of color television in Leningrad took place from the experimental station of the Leningrad Electrotechnical Institute of Communications.

1965. - the Kozitsky plant developed and produced the first tube-semiconductor TV "Evening".

November 29, 1965– The first transmission of color television programs via the SECAM system from Moscow to Paris via the Molniya-1 communication satellite was carried out.

1966. - The Kuntsevsky Mechanical Plant in Moscow developed and produced a small-sized portable TV set "Youth", assembled entirely on transistors.

May 28, 1966– The first transmission of color television programs via the SECAM system from Paris to Moscow via the Molniya-1 communication satellite was carried out.

November 2, 1967- A network of stations for receiving television programs from artificial Earth satellites "Lightning - 1", called "Orbita", was put into operation.

November 4, 1967- The All-Union Radio and Television Transmitting Station of the Ministry of Communications of the USSR was put into operation.

1970. – Ultra-pure quartz fiber made it possible to transmit a light beam at a distance of up to 2 km.

September 5, 1982– The first satellite teleconference "Moscow - Los Angeles" dedicated to the dialogue between musical groups of the USSR and the USA.

April 1988- In the USSR, the use of a set of wearable television journalistic equipment with a VCR began.

February 1999– start of multi-channel digital satellite TV broadcasting (“NTV-plus”). Transmit up to 69 TV channels.

2004. – The Government of the Russian Federation decides to introduce digital TV broadcasting via the European DVB system.

The history of the development of communication lines in Russia The first long-distance overhead line was built between St. Petersburg and Warsaw in 1854. In the 1870s, an overhead communication line from St. Petersburg to Vladivostok L = 10 thousand km was put into operation. In 1939, a high-frequency communication line was put into operation from Moscow to Khabarovsk L = 8,300 thousand km. In 1851, a telegraph cable was laid from Moscow to St. Petersburg, insulated with gutta-percha tape. In 1852, the first submarine cable was laid across the Northern Dvina. In 1866, a cable transatlantic telegraph line between France and the United States was put into operation.

The history of the development of communication lines in Russia In the years in Russia, the first overhead city telephone networks were built (the cable totaled up to 54 wires with air-paper insulation) In 1901, the construction of an underground city telephone network began in Russia winding to artificially increase the inductance. Since 1917, a telephone amplifier based on vacuum tubes has been developed and tested on the line, in 1923 telephone communication with amplifiers on the Kharkov-Moscow-Petrograd line was carried out. Since the beginning of the 1930s, multichannel transmission systems based on coaxial cables began to develop.

The history of the development of communication lines in Russia In 1936, the first coaxial HF telephone line for 240 channels was put into operation. In 1956, an underwater coaxial telephone and telegraph trunk was built between Europe and America. In 1965, the first experimental waveguide lines and cryogenic cable lines with very low attenuation appeared. By the beginning of the 1980s, fiber-optic communication systems had been developed and tested in real conditions.

Types of communication lines (LS) and their properties There are two main types of LS: - lines in the atmosphere (RL radio links) - guide transmission lines (communication lines). typical wavelengths and radio frequencies Extra long waves (VLF) Long waves (LW) Medium waves (MW) Short waves (HF) Ultrashort waves (VHF) Decimeter waves (DCM) Centimeter waves (CM) Millimeter waves (MM) Optical range km ( kHz) km (kHz) 1.0... 0.1 km (0. MHz) m (MHz) m (MHz) .1 m (0. GHz) cm (GHz) mm (GHz) .1 µm

The main disadvantages of RL (radio communications) are: -dependence of the quality of communication on the state of the transmission medium and external electromagnetic fields; -low speed; insufficiently high electromagnetic compatibility in the range of meter waves and above; - the complexity of the transmitter and receiver equipment; - narrow-band transmission systems, especially at long wavelengths and higher.

In order to reduce the shortcomings of the radar, higher frequencies (centimeter, optical ranges) decimeter millimeter range are used. This is a chain of repeaters installed every 50 km-100 km. RRL allow you to receive the number of channels () over distances (up to km); These lines are less susceptible to interference, provide a fairly stable and high-quality connection, but the degree of transmission security through them is insufficient. Radio relay lines (RRL)

Centimeter wave range. SLs allow for multi-channel communication over an “infinite” distance; Satellite communication lines (SL) Advantages of SL - a large area of coverage and transmission of information over long distances. The disadvantage of SL is the high cost of launching a satellite and the complexity of organizing duplex telephone communication.

Advantages of directing LANs - high quality of signal transmission, - high transmission speed, - great protection from the influence of third-party fields, - relative simplicity of terminal devices. Disadvantages of directing LS - high cost of capital and operating costs, - relative duration of establishing a connection.

Radar and LS do not oppose, but complement each other At present, signals from direct current to the optical frequency range are transmitted over communication lines, and the operating wavelength range extends from 0.85 microns to hundreds of kilometers. - cable (CL) - air (VL) - fiber optic (FOCL). The main types of directional drugs:

BASIC REQUIREMENTS FOR COMMUNICATION LINES - communication over distances up to km within the country and up to for international communication; - broadband and suitability for the transmission of various types of modern information (television, telephony, data transmission, broadcasting, transmission of newspaper pages, etc.); - protection of circuits from mutual and external interference, as well as from lightning and corrosion; - stability of the electrical parameters of the line, stability and reliability of communication; - efficiency of the communication system as a whole.

Modern development of cable technology 1. Predominant development of coaxial systems that make it possible to organize powerful communication bundles and transmit television programs over long distances via a single-cable communication system. 2.Creation and implementation of promising communication OKs that provide a large number of channels and do not require scarce metals (copper, lead) for their production. 3. Widespread introduction of plastics (polyethylene, polystyrene, polypropylene, etc.) into cable technology, which have good electrical and mechanical characteristics and make it possible to automate production.

4. The introduction of aluminum, steel and plastic shells instead of lead. The sheaths must be airtight and ensure the stability of the electrical parameters of the cable throughout the entire service life. 5. Development and introduction into production of economical designs of cables for intrazonal communication (single-coaxial, single-quad, unarmoured). 6. Creation of shielded cables that reliably protect the information transmitted through them from external electromagnetic influences and thunderstorms, in particular cables in two-layer sheaths such as aluminum steel and aluminum lead.

7. Increasing the electrical strength of the insulation of communication cables. A modern cable must simultaneously have the properties of both a high-frequency cable and a power electric cable, and ensure the transmission of high voltage currents for remote power supply of unattended amplifying points over long distances.

Communication lines arose simultaneously with the advent of the electric telegraph. The first communication lines were cable. However, due to the imperfection of the cable design, underground cable communication lines soon gave way to overhead ones. The first long-distance overhead line was built in 1854 between St. Petersburg and Warsaw. In the early 70s of the last century, an overhead telegraph line was built from St. Petersburg to Vladivostok, about 10 thousand km long. In 1939, the world's largest high-frequency telephone line Moscow-Khabarovsk, 8300 km long, was put into operation.

The creation of the first cable lines is associated with the name of the Russian scientist P.L. Schilling. As early as 1812, Schilling in St. Petersburg demonstrated the explosions of sea mines, using an insulated conductor he had created for this purpose.

In 1851, simultaneously with the construction of the railway between Moscow and St. Petersburg, a telegraph cable was laid, insulated with gutta-percha. The first submarine cables were laid in 1852 across the Northern Dvina and in 1879 across the Caspian Sea between Baku and Krasnovodsk. In 1866, the transatlantic cable telegraph line between France and the United States was put into operation.

In 1882-1884. in Moscow, Petrograd, Riga, Odessa, the first urban telephone networks in Russia were built. In the 90s of the last century, the first cables, numbering up to 54 wires, were suspended on the city telephone networks of Moscow and Petrograd. In 1901, the construction of an underground city telephone network began.

The first designs of communication cables, dating back to the beginning of the 20th century, made it possible to carry out telephone transmission over short distances. These were the so-called urban telephone cables with air-paper insulation and twisted in pairs. In 1900-1902. a successful attempt was made to increase the transmission range by artificially increasing the inductance of cables by including inductors in the circuit (Pupin's proposal), as well as the use of conductive wires with a ferromagnetic winding (Kruppa's proposal). Such methods at that stage made it possible to increase the range of telegraph and telephone communications several times.

An important stage in the development of communication technology was the invention, and starting from 1912-1913. mastering the production of electronic lamps. In 1917 V.I. Kovalenkov developed and tested on the line a telephone amplifier based on electronic tubes. In 1923, a telephone connection was made with amplifiers on the Kharkov-Moscow-Petrograd line.

In the 1930s, the development of multichannel transmission systems began. Subsequently, the desire to expand the range of transmitted frequencies and increase the bandwidth of the lines led to the creation of new types of cables, the so-called coaxial. But their mass production dates back only to 1935, when new high-quality dielectrics such as escapon, high-frequency ceramics, polystyrene, styroflex, etc. appeared. These cables allow the transmission of energy at a frequency of currents up to several million hertz and allow them to transmit television programs over long distances. The first coaxial line for 240 HF telephony channels was laid in 1936. The first transatlantic submarine cables, laid in 1856, organized only telegraph communications, and only 100 years later, in 1956, an underwater coaxial trunk was built between Europe and America for multichannel telephony.

In 1965-1967. Experimental waveguide communication lines appeared for transmitting broadband information, as well as cryogenic superconducting cable lines with very low attenuation. Since 1970, work has been actively developed on the creation of light guides and optical cables using visible and infrared radiation in the optical wave range.

The creation of a fiber light guide and the obtaining of continuous generation of a semiconductor laser played a decisive role in the rapid development of fiber-optic communication. By the beginning of the 1980s, fiber-optic communication systems had been developed and tested in real conditions. The main areas of application of such systems are the telephone network, cable television, intra-object communication, computer technology, the control and management system for technological processes, etc.

Cabling and wiring products and accessories

The history of the emergence and development of power lines in Russia

The first case of transmitting an electrical signal over a distance is considered to be an experiment conducted in the middle of the 18th century by the abbe J-A Nollet: two hundred monks of the Carthusian monastery, on his instructions, took hold of a metal wire and stood in a line more than a mile long. When the inquisitive abbot discharged the electric capacitor onto the wire, all the monks were immediately convinced of the reality of electricity, and the experimenter of the speed of its distribution. Of course, these two hundred martyrs did not realize that they formed the first power line in history.

1874 Russian engineer F.A. Pirotsky suggested using railway rails as a conductor of electrical energy. At that time, the transmission of electricity through wires was accompanied by large losses (when transmitting direct current, the losses in the wire reached 75%). It was possible to reduce line losses by increasing the cross section of the conductor. Pirotsky conducted experiments on the transmission of energy along the rails of the Sestroretsk railway. Both rails were isolated from the ground, one of them served as a direct wire, the second as a return one. The inventor tried to use the idea for the development of urban transport and put a small trailer on the conductor rails. However, this turned out to be unsafe for pedestrians. However, much later, such a system was developed in the modern metro.

The famous electrical engineer Nikola Tesla dreamed of creating a wireless power transmission system to anywhere in the world. In 1899, he undertook the construction of a transatlantic communication tower, hoping to realize his electrical ideas under the guise of a commercially profitable enterprise. Under his leadership, a giant 200 kW radio station was built in Colorado. In 1905, a trial run of the radio station took place. According to eyewitnesses, lightning flashed around the tower, an ionized environment shone. Journalists claimed that the inventor lit the sky thousands of miles above the expanses of the ocean. However, such a communication system soon turned out to be too expensive, and ambitious plans remained unrealized, only giving rise to a whole mass of theories and rumors (from the “rays of death” to the Tunguska meteorite - everything was attributed to the activities of N. Tesla).

Thus, overhead power lines were the most optimal way out at that time. By the early 1890s, it became clear that it was cheaper and more practical to build power plants near fuel and water resources, and not, as was done before, near energy consumers. For example, the first thermal power plant in our country was built in 1879, in the then capital, St. Petersburg, specifically to illuminate the Liteiny Bridge; city in Europe, which was completely and exclusively illuminated by electricity. However, these resources were often removed from large cities, which traditionally acted as centers of industry. There was a need to transmit electricity over long distances. The transmission theory was simultaneously developed by the Russian scientist D.A. Lachinov, and the French electrical engineer M. Despres. At the same time, the American George Westinghouse was engaged in the creation of transformers, however, the world's first transformer (with an open core) was created by P.N. Yablochkov, who received a patent for it back in 1876.

At the same time, the question arose about the use of alternating or direct current. This issue was also interested in the creator of the arc light bulb P.N. Yablochkov, who foreshadowed a great future for high voltage alternating current. These conclusions were supported by another domestic scientist, M.O. Dolivo-Dobrovolsky.

In 1891, he built the first three-phase power transmission line, which reduced losses by up to 25%. At that time, the scientist worked for AEG, owned by T. Edison. This company was invited to participate in the International Electrical Exhibition in Frankfurt am Main, where the issue of further use of alternating or direct current was decided. An international testing commission was organized under the chairmanship of the German scientist G. Helmholtz. The members of the commission included the Russian engineer R.E. Klasson. It was assumed that the commission would test all the proposed systems and give an answer to the question of choosing the type of current and a promising power supply system.

M.O. Dolivo-Dobrovolsky decided to transfer the energy of the waterfall to the river through electricity. Neckar (near the town of Laufen) to the exhibition area in Frankfurt. The distance between these two points was 170 km, although up to this point the transmission distance usually did not exceed 15 km. In just one year, the Russian scientist had to stretch power lines on wooden poles, create the necessary motors and transformers (“induction coils,” as they were then called), and he brilliantly coped with this task in cooperation with the Swiss company Oerlikon. In August 1891, a thousand incandescent lamps were lit for the first time at the exhibition, powered by current from the Laufen hydroelectric station. A month later, Dolivo-Dobrovolsky's engine set in motion a decorative waterfall - there was a kind of energy chain, a small artificial waterfall was powered by the energy of a natural waterfall, 170 km away from the first one.

Thus, the main energy problem of the late 19th century, the problem of transmitting electricity over long distances, was resolved. In 1893, engineer A.N. Schensnovich builds the world's first industrial power plant on these principles at the Novorossiysk workshops of the Vladikavkaz railway.

In 1891, on the basis of the Telegraph School in St. Petersburg, the Electrotechnical Institute was created, which began training personnel for the upcoming electrification of the country.

Wires for power transmission lines were originally imported from abroad, however, they quickly began to be produced at the Kolchuginsky Brass and Copper Rolling Plant, the United Cable Plants enterprise and the Podobedov plant. But the supports were already produced in Russia - though they were used before mainly for telegraph and telephone wires. At first, difficulties arose in everyday life - the illiterate population of the Russian Empire was suspicious of the pillars, decorated with tablets on which a skull was drawn.

The mass construction of power transmission lines begins at the end of the 19th century, this is due to the electrification of industry. The main task that was solved at this stage was the connection of power plants with industrial areas. The voltages were small, as a rule, up to 35 kV, the task of networking was not put forward. Under these conditions, the tasks were easily solved with the help of wooden single-column and U-shaped supports. The material was available, cheap and fully met the requirements of the time. All these years, the design of supports and wires has been continuously improved.

For mobile electric transport, the principle of underground electric traction was known, used to power trains in Cleveland and Budapest. However, this method was inconvenient in operation, and underground cable power lines were used only in cities for street lighting and power supply to private houses. Until now, the cost of underground power lines exceeds the cost of overhead lines by 2-3 times.

In 1899, the First All-Russian Electrotechnical Congress took place in Russia. Nikolai Pavlovich Petrov, former chairman of the Imperial Russian Technical Society, professor of the Military Engineering Academy and Institute of Technology, became its chairman. The congress brought together over five hundred people interested in electrical engineering, among them were people of the most diverse professions and with the most diverse education. They were united either by a common work in the field of electrical engineering, or by a common interest in the development of electrical engineering in Russia. Until 1917, seven such congresses were held, the new government continued this tradition.

In 1902, the Baku oil fields were supplied with electricity, the power transmission line transmitted electricity with a voltage of 20 kV.

In 1912, on a peat bog near Moscow, construction began on the world's first power plant operating on peat. The idea belonged to R.E. Klasson, who took advantage of the fact that coal, which was used mainly by power plants of that time, had to be brought to Moscow. This raised the price of electricity, and the peat power plant, with a transmission line of 70 km, quickly paid for itself. It still exists - now it is GRES-3 in the city of Noginsk.

The electric power industry in the Russian Empire in those years was predominantly owned by foreign firms and entrepreneurs, for example, a controlling stake in the largest joint-stock company Electric Lighting Society 1886, which built almost all power plants in pre-revolutionary Russia, belonged to the German company Siemens and Halske, already known to us from history cable industry (see "CABLE-news", No. 9, pp. 28-36). Another JSC - United Cable Plants, was controlled by the AEG concern. Much of the equipment was imported from abroad. The Russian energy industry and its development lagged far behind the advanced countries of the world. By 1913, the Russian Empire ranked 8th in the world in terms of the amount of electricity generated.

With the outbreak of the First World War, the production of equipment for power lines is reduced - the front needed other products that could produce the same factories - telephone field wire, mine cable, enameled wire. Some of these products were first mastered by domestic production, as many import deliveries were stopped due to the war. During the war, the Electric Joint Stock Company of the Donetsk Basin built a 60,000 kW power plant and brought equipment for it.

By the end of 1916, the fuel and raw materials crisis caused a sharp drop in production at factories, which continued into 1917. After the October Socialist Revolution, all factories and enterprises were nationalized by decree of the SNK (Council of People's Commissars). By order of the Supreme Economic Council (Supreme Council of the National Economy) of the RSFSR in December 1918, all enterprises associated with the production of wires and power lines were placed at the disposal of the Department of the Electrical Industry. Practically everywhere a collegial administration was created, in which both the workers representing the "new government" and representatives of the former administrative and engineering corps participated. Immediately upon coming to power, the Bolsheviks paid great attention to electrification, for example, already during the years of the civil war, despite the devastation, blockade and intervention, 51 power plants with a total capacity of 3500 kW were built in the country.

The GOELRO plan, drawn up in 1920 under the guidance of a former St. Petersburg fitter for power lines and cable networks, in the future academician G.M. Krzhizhanovsky, forced the development of all types of electrical engineering. According to it, twenty thermal and ten hydroelectric stations were to be built with a total capacity of 1,750,000 kW. The department of the electrical industry in 1921 was transformed into the Main Directorate of the Electrical Industry of the Supreme Council of National Economy - Glavelectro. The first head of Glavelectro was V.V. Kuibyshev.

In 1923, the "First All-Russian Agricultural and Handicraft-Industrial Exhibition" opened in Gorky Park. As a result of the exhibition, the Russkabel plant received a diploma of the first degree for its contribution to electrification and the manufacture of high-voltage cables.

As the voltage increased and, accordingly, the weight of the wire, a transition was made from wooden to metal poles for power lines. In Russia, the first line on metal supports appeared in 1925 - a double-circuit 110 kV overhead line, connecting Moscow and Shaturskaya GRES.

In 1926, the first central dispatch service in the country was created in the Moscow energy system, which still exists.

In 1928, the USSR began to manufacture its own power transformers, which were produced by the specialized Moscow Transformer Plant.

In the 1930s, electrification continued at an ever-increasing pace. Large power plants are being created (Dneproges, Stalingradskaya GRES, etc.), the voltages of the transmitted electricity are increasing (for example, the Dneproges-Donbass transmission line operates with a voltage of 154 kV; and the Nizhne-Svirskaya HPP - Leningrad transmission line with a voltage of 220 kV). At the end of the 1930s, the Moscow-Volzhskaya HPP line was being built, which operated with an ultra-high voltage of 500 kV. Unified energy systems of large regions are emerging. All this required the improvement of metal supports. Their designs were continuously improved, the number of standard supports was expanded, a mass transition was made to supports with bolted connections and lattice supports.

Wooden poles are also used at this time, but their area is usually limited to voltages up to 35 kV. They link mostly non-industrial rural areas.

During the years of the pre-war five-year plans (1929-1940), large energy systems were created on the territory of the country - in Ukraine, Belarus, in Leningrad, Moscow.

During the war, out of a total installed capacity of ten million kW of power plants, five million kW were put out of action. During the war years, 61 large power plants were destroyed, a large amount of equipment was taken out by the occupiers to Germany. Part of the equipment was blown up, part was evacuated to the Urals and the East of the country in record time and put into operation there to ensure the work of the defense industry. During the war years, a 100 MW turbine unit was put into operation in Chelyabinsk.

With their heroic work, Soviet power engineers ensured the operation of power plants and networks during the difficult war years. During the advance of the fascist armies to Moscow in 1941, the Rybinsk hydroelectric power station was put into operation, which ensured the energy supply of Moscow with a lack of fuel. Novomoskovsk GRES, captured by the Nazis, was destroyed. The Kashirskaya GRES supplied electricity to Tula's industry, and at one time a transmission line was in operation that crossed the territory occupied by the Nazis. This power line was restored by power engineers in the rear of the German army. The Volkhov hydroelectric power station, which suffered from German aviation, was also put back into operation. From it, along the bottom of Lake Ladoga (via a specially laid cable), electricity was supplied to Leningrad throughout the blockade.

In 1942, in order to coordinate the work of three regional energy systems: Sverdlovsk, Perm and Chelyabinsk, the first Joint Dispatch Office was created - ODU of the Urals. In 1945, the ODU of the Center was created, which marked the beginning of the further unification of energy systems into a single network throughout the country.

After the war, power grids were not only repaired and restored, but new ones were also built. By 1947, the USSR took second place in the world in terms of electricity production. The United States came first.

In the 1950s, new hydroelectric power stations were built - Volzhskaya, Kuibyshevskaya, Kakhovskaya, Yuzhnouralskaya.

From the end of the 1950s, the stage of rapid growth of electric grid construction began. The length of overhead transmission lines doubled every five years. More than thirty thousand kilometers of new transmission lines were built annually. At this time, reinforced concrete supports for power transmission lines, with "prestressed racks", are massively introduced and used. They usually had lines with a voltage of 330 and 220 kV.

In June 1954, a nuclear power plant in the city of Obninsk began operation, with a capacity of 5 MW. It was the world's first nuclear power plant for pilot purposes.

Abroad, the first nuclear power plant for industrial use was put into operation only in 1956 in the English city of Calder Hall. A year later, the nuclear power plant in the American Shippingport was put into operation.

Power lines of high voltage direct current are also being constructed. The first experimental power transmission line of this type was created in 1950, on the Kashira-Moscow direction, 100 km long, 30 MW in power and 200 kV in voltage. The second on this path were the Swedes. In 1954, they connected the power system of the island of Gotland along the bottom of the Baltic Sea with the power system of Sweden through a 98-kilometer single-pole power line, 100 kV and 20 MW.

In 1961, the first units of the world's largest Bratsk hydroelectric power station were launched.

The unification of metal supports, carried out at the end of the 60s, actually determined the basic set of support structures used to this day. Over the past 40 years, as well as for metal poles, the design of reinforced concrete poles has not changed much. Today, almost all network construction in Russia and the CIS countries is based on the scientific and technological base of the 60-70s.

The world practice of building power transmission lines was not much different from the domestic one until the mid-60s. However, in recent decades, our practices have diverged significantly. In the West, reinforced concrete has not received such distribution as a material for supports. They took the path of building lines on multifaceted metal supports.

In 1977, the Soviet Union produced more electricity than all the countries of Europe combined - 16% of world production.

By connecting regional power grids, the Unified Energy System of the USSR is created - the largest electric power system, which was then connected to the energy systems of Eastern Europe and formed an international energy system, called the "Mir". By 1990, the UES of the USSR included 9 out of 11 energy associations of the country, covering 2/3 of the territory of the USSR, where more than 90% of the population lived.

It should be noted that in a number of technical indicators (for example, the scale of power plants and the voltage levels of high-voltage power lines), the Soviet Union occupied leading positions in the world.

In the 1980s, an attempt was made in the USSR to introduce multifaceted supports manufactured by the Volga Mechanical Plant into mass construction. However, the lack of necessary technologies determined the design flaws of these supports, which led to failure. This issue was revisited only in 2003.

After the collapse of the Soviet Union, power engineers faced new problems. Extremely insignificant funds were allocated to maintain the state of power lines and their restoration, the decline of industry led to the degradation and even destruction of many power lines. There was such a phenomenon as the theft of wires and cables for their subsequent delivery to the collection points of non-ferrous metal as scrap metal. Despite the fact that many of the “earners” die in this criminal trade, and their income is very insignificant, the number of such cases has practically not decreased so far. This is caused by a sharp decline in the standard of living in the regions, since this crime is mainly committed by marginalized people without work and place of residence.

In addition, ties with the countries of Eastern Europe and the former republics of the USSR, previously connected by a single energy system, were broken. In November 1993, due to a large power shortage in Ukraine, a forced transition to separate operation of the UES of Russia and the UES of Ukraine was carried out, which led to the separate operation of the UES of Russia with the rest of the energy systems that are part of the Mir energy system. In the future, the parallel operation of the power systems that are part of Mir with the central dispatching office in Prague was not resumed.

Over the past 20 years, the physical deterioration of high voltage networks has increased significantly and, according to some researchers, has reached more than 40%. In distribution networks, the situation is even more difficult. This is compounded by the ever-increasing energy consumption. There is also obsolescence of equipment. Most of the objects in terms of technical level correspond to their Western counterparts of 20-30 years ago. Meanwhile, the world energy industry does not stand still, research is being carried out in the field of creating new types of power transmission lines: cryogenic, cryoresistor, semi-open, open, etc.

The domestic electric power industry faces the most important issue of solving all these new challenges and tasks.

Literature
1. Shukhardin S. Technology in its historical development.
2. Kaptsov N. A. Yablochkov is the glory and pride of Russian electrical engineering.
3. Laman N.K., Belousova A.N., Krechetnikova Yu.I. The Elektroprovod plant is 200 years old. M., 1985.
4. Russian cable / Ed. M.K. Portnova, N.A. Arskoy, R.M. Lakernik, N.K. Laman, V.G. Radchenko. M., 1995.
5. Valeeva N.M. Time leaves a mark. M., 2009.
6. Gorbunov O.I., Ananiev A.S., Perfiletov A.N., Shapiro R.P-A. 50 years of the Research Design and Technological Cable Institute. History essays. St. Petersburg: 1999.
8. Shitov M.A. Northern cable. L., 1979.
7. Sevkabel. 120 years / ed. L. Ulitina - St. Petersburg, 1999.
9. Kislitsyn A.L. Transformers. Ulyanovsk: UlGTU, 2001.
10. Turchin I.Ya. Engineering equipment of thermal power plants and installation works. M .: "Higher School", 1979.
11. Steklov V. Yu. Development of the electric power economy of the USSR. 3rd ed. M., 1970.
12. Zhimerin D.G., History of electrification of the USSR, L., 1962.
13. Lychev P.V., Fedin V.T., Pospelov G.E. Electrical systems and networks, Minsk. 2004
14. History of the cable industry // CABLE-news. No. 9. pp. 28-36.

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(Document)

Gitin V.Ya., Kochanovsky L.N. Fiber Optic Transmission Systems (Document)

Lectures - Fiber Optic Transmission Systems (Lecture)

Sharvarko V.G. Fiber optic communication lines (Document)

Degtyarev A.I., Tezin A.V. Fiber Optic Transmission Systems (Document)

Fokin V.G. Fiber Optic Transmission Systems (Document)

Ivanov V.A. Lectures: Measurements on fiber optic transmission systems (Document)

Okosi T. Fiber Optic Sensors (Document)

n1.doc

Content

Introduction
Main part

History of the development of communication lines
Design and characteristics of optical communication cables
2. Optical fibers and features of their manufacture
3. Optical cable designs
Basic requirements for communication lines
Advantages and disadvantages of optical cables

Conclusion
Bibliography

Introduction
Today, more than ever, the regions of the CIS countries need communication, both quantitatively and qualitatively. The leaders of the regions are primarily concerned about the social aspect of this problem, because the telephone is a matter of prime necessity. Communication also affects the economic development of the region, its investment attractiveness. At the same time, telecommunications operators, who spend a lot of effort and money to support the decrepit telephone network, are still seeking funds for the development of their networks, for digitization, and the introduction of fiber-optic and wireless technologies.

At this point in time, there is a situation where almost all major Russian departments are carrying out a large-scale modernization of their telecommunications networks.

Over the last period of development in the field of communication, optical cables (OC) and fiber-optic transmission systems (FOTS) have become most widespread, which by their characteristics far exceed all traditional cables of the communication system. Communication via fiber-optic cables is one of the main directions of scientific and technological progress. Optical systems and cables are used not only for the organization of urban and long-distance telephone communications, but also for cable television, video telephony, radio broadcasting, computer technology, technological communications, etc.

Using fiber optic communication, the amount of information transmitted increases dramatically compared to such widespread means as satellite communications and radio relay lines, this is due to the fact that fiber optic transmission systems have a wider bandwidth.

For any communication system, three factors are important:

The information capacity of the system, expressed in the number of communication channels, or the information transfer rate, expressed in bits per second;

Attenuation, which determines the maximum length of the regeneration section;

Resistance to environmental influences;

The most important factor in the development of optical systems and communication cables was the appearance of an optical quantum generator - a laser. The word laser is made up of the first letters of the phrase Light Amplification by Emission of Radiation - light amplification by induced radiation. Laser systems operate in the optical wavelength range. If frequencies are used for cable transmission - megahertz, and for waveguides - gigahertz, then for laser systems the visible and infrared spectrum of the optical wave range (hundreds of gigahertz) is used.

The guide system for fiber-optic communication systems are dielectric waveguides, or fibers, as they are called because of the small transverse dimensions and method of obtaining. At the time when the first fiber was produced, the attenuation was on the order of 1000 dB/km, this was due to losses due to various impurities present in the fiber. In 1970, optical fibers with an attenuation of 20 dB/km were created. The core of this fiber was made of quartz with the addition of titanium to increase the refractive index, and pure quartz served as a cladding. In 1974 attenuation was reduced to 4 dB / km, and in 1979. Optical fibers with an attenuation of 0.2 dB/km at a wavelength of 1.55 µm were obtained.

Advances in the technology of obtaining light guides with low losses stimulated work on the creation of fiber optic communication lines.

Optical fiber communication lines have the following advantages over conventional cable lines:

High noise immunity, insensitivity to external electromagnetic fields and practically no crosstalk between individual fibers laid together in a cable.

Significantly higher bandwidth.

Small weight and overall dimensions. This reduces the cost and time of laying the optical cable.

Complete electrical isolation between the input and output of the communication system, so no common transmitter and receiver grounding is required. You can repair the optical cable without turning off the equipment.

The absence of short circuits, as a result of which optical fibers can be used to cross hazardous areas without fear of short circuits, which are the cause of fire in areas with combustible and flammable media.

Potentially low cost. Although optical fibers are made from ultra-clear glass with impurities of less than a few parts per million, their cost is not high when mass-produced. In addition, the production of optical fibers does not use such expensive metals as copper and lead, the reserves of which on Earth are limited. The cost of electrical lines of coaxial cables and waveguides is constantly increasing both with a shortage of copper and with an increase in the cost of energy costs for the production of copper and aluminum.

There has been tremendous progress in the development of fiber optic communication lines (FOCL) around the world. Currently, fiber optic cables and transmission systems for them are produced by many countries of the world.

Particular attention here and abroad is paid to the creation and implementation of single-mode transmission systems over optical cables, which are considered as the most promising direction in the development of communication technology. The advantage of single-mode systems is the possibility of transmitting a large flow of information over the required distances with large lengths of regeneration sections. Already now there are fiber optic lines for a large number of channels with a regeneration section length of 100 ... 150 km. Recently, 1.6 million km are manufactured annually in the USA. optical fibers, with 80% of them in a single-hearth version.

Modern domestic second-generation fiber optic cables have been widely used, the production of which has been mastered by the domestic cable industry, they include cables of the type:

OKK - for urban telephone networks;

OKZ - for intrazonal;

OKL - for backbone communication networks;

Fiber-optic transmission systems are used in all sections of the primary VSS network for backbone, zonal and local communications. The requirements for such transmission systems differ in the number of channels, parameters, and technical and economic indicators.

On backbone and zonal networks, digital fiber-optic transmission systems are used, on local networks, digital fiber-optic transmission systems are also used to organize connecting lines between exchanges, and on the subscriber section of the network, both analog (for example, to organize a television channel) and digital transmission systems can be used. .

The maximum length of the linear paths of the main transmission systems is 12,500 km. With an average length of about 500 km. The maximum length of the linear paths of the transmission systems of the intrazonal primary network can be no more than 600 km. With an average length of 200 km. The maximum length of urban connecting lines for various transmission systems is 80...100 km.
Man has five senses, but one of them is especially important - this is vision. Through the eyes, a person perceives most of the information about the world around him 100 times more than through hearing, not to mention touch, smell and taste.

used fire and then various types of artificial light sources to give signals. Now in the hands of man was both the light source and the process of light modulation. He actually built what today we call an optical communication line or an optical communication system, including a transmitter (source), a modulator, an optical cable line and a receiver (eye). Having defined the conversion of a mechanical signal into an optical one as modulation, for example, opening and closing a light source, we can observe the reverse process in the receiver - demodulation: the conversion of an optical signal into a signal of a different kind for further processing in the receiver.

Such processing may be, for example, the transformation

of the light image in the eye into a sequence of electrical impulses

human nervous system. The brain is included in the processing process as the last link in the chain.

Another very important parameter used in message transmission is the modulation rate. The eye is limited in this respect. It is well adapted to the perception and analysis of complex pictures of the surrounding world, but cannot follow simple brightness fluctuations when they follow faster than 16 times per second.

History of the development of communication lines

The creation of the first cable lines is associated with the name of the Russian scientist P. L. Schilling. As early as 1812, Schilling in St. Petersburg demonstrated the explosions of sea mines, using an insulated conductor he had created for this purpose.

In 1851, simultaneously with the construction of the railway between Moscow and St. Petersburg, a telegraph cable was laid, insulated with gutta-percha. The first submarine cables were laid in 1852 across the Northern Dvina and in 1879 across the Caspian Sea between Baku and Krasnovodsk. In 1866, a cable transatlantic telegraph line between France and the United States was put into operation,

An important stage in the development of communication technology was the invention, and starting from 1912-1913. mastering the production of electronic lamps. In 1917, V. I. Kovalenkov developed and tested a telephone amplifier using electronic tubes on the line. In 1923, a telephone connection was made with amplifiers on the Kharkov-Moscow-Petrograd line.

In the 1930s, the development of multichannel transmission systems began. Subsequently, the desire to expand the range of transmitted frequencies and increase the bandwidth of the lines led to the creation of new types of cables, the so-called coaxial. But their mass production dates back only to 1935, by the time new high-quality dielectrics such as escapon, high-frequency ceramics, polystyrene, styroflex, etc. appeared. These cables allow the transfer of energy at a current frequency of up to several million hertz and allow the transmission of television programs over long distances. The first coaxial line for 240 HF telephony channels was laid in 1936. The first transatlantic submarine cables, laid in 1856, organized only telegraph communications, and only 100 years later, in 1956, an underwater coaxial trunk was built between Europe and America for multichannel telephony.

In Russia and other countries, urban and long-distance fiber-optic communication lines have been laid. They are given a leading place in the scientific and technological progress of the communications industry.
Design and characteristics of optical communication cables
Varieties of optical communication cables

An optical cable consists of quartz glass optical fibers (light guides) twisted according to a certain system, enclosed in a common protective sheath. If necessary, the cable may contain power (strengthening) and damping elements.

Existing OKs according to their purpose can be classified into three groups: main, zonal and urban. Underwater, object and installation OK are allocated in separate groups.

Trunk OK are intended to transmit information over long distances and a significant number of channels. They must have low attenuation and dispersion and high information throughput. A single-mode fiber with a core and cladding of 8/125 µm is used. Wavelength 1.3...1.55 µm.

Zonal OKs serve to organize multi-channel communication between the regional center and regions with a communication range of up to 250 km. Gradient fibers with dimensions of 50/125 µm are used. Wavelength 1.3 µm.

City OK are applied as connecting between city automatic telephone exchanges and communication centers. They are designed for short distances (up to |10 km) and a large number of channels. Fibers - gradient (50/125 microns). Wavelength 0.85 and 1.3 µm. These lines, as a rule, operate without intermediate linear regenerators.

Submarine OK intended for communication through large water barriers. They must have high mechanical tensile strength and have reliable moisture-resistant coatings. It is also important for submarine communications to have low attenuation and long regeneration lengths.

Object OKs serve to convey information within an object. This includes institutional and video telephone communications, the internal cable television network, as well as on-board information systems of mobile objects (aircraft, ship, etc.).

Mounting OK are used for intra- and inter-unit mounting of equipment. They are made in the form of bundles or flat ribbons.
Optical fibers and features of their manufacture

The main element of the optical fiber is an optical fiber (optical fiber), made in the form of a thin cylindrical glass fiber, through which light signals are transmitted with wavelengths of 0.85 ... 1.6 μm, which corresponds to a frequency range of (2.3 ... 1 ,2) 10 14 Hz.

The light guide has a two-layer design and consists of a core and a cladding with different refractive indices. The core serves to transmit electromagnetic energy. The purpose of the shell is to create the best conditions for reflection at the “core-shell” interface and protection from interference from the surrounding space.

The core of the fiber, as a rule, consists of quartz, and the cladding can be quartz or polymer. The first fiber is called quartz-quartz, and the second is called quartz-polymer (organosilicon compound). Based on the physico-optical characteristics, preference is given to the first. Quartz glass has the following properties: refractive index 1.46, thermal conductivity 1.4 W/mk, density 2203 kg/m 3 .

Outside the light guide there is a protective coating to protect it from mechanical influences and apply colors. The protective coating is usually made in two layers: first, an organosilicon compound (SIEL), and then an epoxy acrylate, fluoroplastic, nylon, polyethylene, or varnish. Overall fiber diameter 500...800 µm

Three types of optical fibers are used in existing optical fiber designs: stepped with a core diameter of 50 μm, gradient with a complex (parabolic) refractive index profile of the core, and single-mode with a thin core (6 ... 8 μm)
In terms of frequency bandwidth and transmission range, single-mode fibers are the best, and stepped ones are the worst.

The most important problem of optical communication is the creation of optical fibers (OF) with low losses. Quartz glass is used as a starting material for the manufacture of optical fibers, which is a good medium for the propagation of light energy. However, as a rule, glass contains a large amount of foreign impurities, such as metals (iron, cobalt, nickel, copper) and hydroxyl groups (OH). These impurities lead to a significant increase in losses due to the absorption and scattering of light. To obtain OF with low losses and attenuation, it is necessary to get rid of impurities so that there is a chemically pure glass.

At present, the most widely used method for creating OF with low losses is by chemical vapor deposition.

Obtaining OF by chemical vapor deposition is carried out in two stages: a two-layer quartz preform is manufactured and a fiber is drawn from it. The workpiece is made as follows
A jet of chlorinated quartz and oxygen is fed into a hollow quartz tube with a refractive index 0.5...2 m long and 16...18 mm in diameter. As a result of a chemical reaction at a high temperature (1500...1700°C), pure quartz is deposited in layers on the inner surface of the tube. Thus, the entire internal cavity of the tube is filled, except for the very center. To eliminate this air channel, an even higher temperature (1900° C.) is applied, due to which the collapse occurs and the tubular billet is transformed into a solid cylindrical billet. The pure deposited quartz then becomes the core of the optical fiber with a refractive index , and the tube itself acts as a shell with a refractive index . The drawing of the fiber from the workpiece and its winding on the receiving drum is carried out at the glass softening temperature (1800...2200°C). More than 1 km of optical fiber is obtained from a preform 1 m long.
The advantage of this method is not only obtaining OF with a core of chemically pure quartz, but also the possibility of creating gradient fibers with a given refractive index profile. This is done: through the use of alloyed quartz with titanium, germanium, boron, phosphorus or other reagents. Depending on the additive used, the refractive index of the fiber may vary. So, germanium increases, and boron reduces the refractive index. By selecting the recipe of doped quartz and observing a certain amount of additive in the layers deposited on the inner surface of the tube, it is possible to provide the required pattern of change over the cross section of the fiber core.

Optical cable designs

OK constructions are mainly determined by the purpose and scope of their application. In this regard, there are many constructive options. Currently, a large number of types of cables are being developed and manufactured in various countries.

However, the whole variety of existing types of cables can be divided into three groups

concentric stranded cables
shaped core cables
flat ribbon cables.

The cables of the first group have a traditional twisted concentric core, similar to electric cables. Each subsequent winding of the core has six more fibers compared to the previous one. Such cables are known mainly with the number of fibers 7, 12, 19. Most often, the fibers are located in separate plastic tubes, forming modules.

The cables of the second group have a figured plastic core in the center with grooves in which the optical fibers are placed. The grooves and, accordingly, the fibers are located along the helicoid, and therefore they do not experience a longitudinal effect on the gap. Such cables can contain 4, 6, 8 and 10 fibers. If it is necessary to have a high capacity cable, then several primary modules are used.

A ribbon type cable consists of a stack of flat plastic tapes in which a certain number of optical fibers are mounted. Most often, there are 12 fibers in the tape, and the number of tapes is 6, 8 and 12. With 12 tapes, such a cable can contain 144 fibers.

In optical cables except OB , usually has the following elements:

power (reinforcing) rods that take on the longitudinal load, at break;
fillers in the form of continuous plastic threads;
reinforcing elements that increase the resistance of the cable under mechanical stress;
outer protective sheaths that protect the cable from the penetration of moisture, vapors of harmful substances and external mechanical influences.

In Russia, various types and designs of OK are manufactured. For the organization of multi-channel communication, mainly four- and eight-fiber cables are used.

Are of interest OK French production. They, as a rule, are completed from unified modules consisting of a plastic rod with a diameter of 4 mm with ribs along the perimeter and ten OBs located along the periphery of this rod. Cables contain 1, 4, 7 such modules. Outside, the cables have an aluminum and then a polyethylene sheath.
The American cable, widely used on the GTS, is a stack of flat plastic tapes containing 12 OFs. The cable can have from 4 to 12 tapes containing 48-144 fibers.

In England, an experimental power transmission line was built with phase wires containing OF for technological communication along power lines. There are four OBs in the center of the power line wire.

Suspended OK are also used. They have a metal cable embedded in the cable sheath. Cables are intended for suspension along overhead line supports and walls of buildings.

For underwater communications, OK is designed, as a rule, with an outer armor cover made of steel wires (Fig. 11). In the center is a module with six OBs. The cable has a copper or aluminum tube. Through the “tube-water” circuit, remote power supply current is supplied to underwater unattended amplifying points.

Basic requirements for communication lines

In general, the requirements imposed by highly developed modern telecommunication technology on long-distance communication lines can be formulated as follows:

communication over distances up to 12,500 km within the country and up to 25,000 for international communications;
broadband and suitability for the transmission of various types of modern information (television, telephony, data transmission, broadcasting, transmission of newspaper pages, etc.);
protection of circuits from mutual and external interference, as well as from lightning and corrosion;
stability of the electrical parameters of the line, stability and reliability of communication;
efficiency of the communication system as a whole.

An intercity cable line is a complex technical structure, consisting of a huge number of elements. Since the line is intended for long-term operation (tens of years) and uninterrupted operation of hundreds and thousands of communication channels must be ensured on it, then to all elements of linear cable equipment, and primarily to cables and cable accessories included in the linear signal transmission path are high requirements. The choice of the type and design of the communication line is determined not only by the process of energy propagation along the line, but also by the need to protect adjacent RF circuits from mutual interfering influences. Cable dielectrics are selected based on the requirement to provide the greatest communication range in RF channels with minimal losses.

In accordance with this, cable technology is developing in the following directions:

Predominant development of coaxial systems, which make it possible to organize powerful communication beams and transmit television programs over long distances via a single-cable communication system.
Creation and implementation of promising communication OKs that provide a large number of channels and do not require scarce metals (copper, lead) for their production.
Widespread introduction of plastics (polyethylene, polystyrene, polypropylene, etc.) into cable technology, which have good electrical and mechanical characteristics and make it possible to automate production.
Introduction of aluminum, steel and plastic sheaths instead of lead. The sheaths must be airtight and ensure the stability of the electrical parameters of the cable throughout the entire service life.
Development and introduction into production of economical designs of cables for intrazonal communication (single-coaxial, single-quad, armorless).
Creation of shielded cables that reliably protect the information transmitted through them from external electromagnetic influences and thunderstorms, in particular cables in two-layer shells of the aluminum-steel and aluminum-lead types.
Increasing the electrical strength of the insulation of communication cables. A modern cable must simultaneously have the properties of both a high-frequency cable and a power electric cable, and ensure the transmission of high voltage currents for remote power supply of unattended amplifying points over long distances.

Advantages of optical cables and their scope

Along with saving non-ferrous metals, and primarily copper, optical cables have the following advantages:

broadband, the ability to transmit a large flow of information (several thousand channels);
low losses and, accordingly, large lengths of broadcast sections (30...70 and 100 km);
small overall dimensions and weight (10 times less than electric cables);
high protection from external influences and crosstalk;
reliable safety technology (no sparks and short circuits).

The disadvantages of optical cables include:

susceptibility of optical fibers to radiation, due to which blackout spots appear and attenuation increases;
hydrogen corrosion of glass, leading to microcracks in the optical fiber and deterioration of its properties.

Advantages and disadvantages of fiber optic communication
Advantages of open communication systems:

Higher ratio of received signal power to radiated power with smaller apertures of transmitter and receiver antennas.
Better spatial resolution with smaller transmitter and receiver antenna apertures
Very small dimensions of the transmitting and receiving modules used for communication over distances up to 1 km
Good communication secrecy
Development of an unused part of the spectrum of electromagnetic radiation
No need to obtain permission to operate the communication system

Disadvantages of open communication systems:

Low suitability for radio broadcasting due to the high directivity of the laser beam.
High required pointing accuracy of transmitter and receiver antennas
Low efficiency of optical emitters
Relatively high noise level in the receiver, due in part to the quantum nature of the optical signal detection process
Influence of Atmospheric Characteristics on Communication Reliability
Possibility of hardware failure.

Advantages of guiding communication systems:

The possibility of obtaining optical fibers with low attenuation and dispersion, which makes it possible to make distances between repeaters large (10 ... 50 km)
Small diameter single fiber cable
Permissibility of fiber bending under small radii
Low weight of optical cable with high information throughput
Low cost fiber material
The possibility of obtaining optical cables that do not have electrical conductivity and inductance
Negligible crosstalk

High communication secrecy: signal tapping is only possible with a direct connection to a separate fiber
Flexibility in implementing the required bandwidth: various types of light guides allow you to replace electrical cables in digital communication systems of all levels of the hierarchy
Possibility of continuous improvement of the communication system

Disadvantages of guiding communication systems:

Difficulty in joining (splicing) optical fibers
The need to lay additional electrically conductive cores in an optical cable to provide power to remotely controlled equipment
The sensitivity of optical fiber to the effects of water when it enters the cable
Optical fiber sensitivity to ionizing radiation
Low efficiency of optical radiation sources with limited radiation power
Difficulties in Implementing the Multiple Access (Parallel) Access Mode Using a Time Division Bus
High noise level in the receiver

Directions of development and application of fiber optics

Broad horizons have opened up for the practical application of OC and fiber-optic transmission systems in such sectors of the national economy as radio electronics, computer science, communications, computer technology, space, medicine, holography, mechanical engineering, nuclear energy, etc. Fiber optics is developing in six areas:

multichannel information transmission systems;
cable TV;
local computer networks;
sensors and systems for collecting, processing and transmitting information;
communications and telemechanics on high-voltage lines;
equipment and installation of mobile objects.

Multichannel FOTS are beginning to be widely used on the backbone and zonal communication networks of the country, as well as for the device of connecting lines between urban exchanges. This is explained by the large information capacity of OK and their high noise immunity. Underwater optical highways are especially efficient and economical.

The use of optical systems in cable television provides high image quality and significantly expands the possibilities of information service for individual subscribers. In this case, a custom reception system is implemented and subscribers are provided with the opportunity to receive images of newspaper pages, magazine pages and reference data from the library and educational centers on their TV screens.

On the basis of OK, local computer networks of various topologies (ring, star, etc.) are created. Such networks make it possible to unite computing centers into a single information system with high bandwidth, improved quality and protection from unauthorized access.

Recently, a new direction in the development of fiber-optic technology has appeared - the use of the mid-infrared wavelength range of 2 ... 10 microns. It is expected that losses in this range will not exceed 0.02 dB/km. This will allow communication over long distances with regeneration sites up to 1000 km. The study of fluorine and chalcogenide glasses with additions of zirconium, barium, and other compounds possessing supertransparency in the infrared wavelength range makes it possible to further increase the length of the regeneration section.

New interesting results are expected in the use of nonlinear optical phenomena, in particular, the soliton regime of optical pulse propagation, when the pulse can propagate without changing its shape or periodically change its shape in the process of propagation along the fiber. The use of this phenomenon in fiber light guides will significantly increase the amount of transmitted information and the communication range without the use of repeaters.

It is very promising to implement the method of frequency division of channels in FOCL, which consists in the fact that radiation from several sources operating at different frequencies is simultaneously introduced into the fiber, and signals are separated at the receiving end using optical filters. This method of channel separation in FOCL is called spectral multiplexing or multiplexing.

When building FOCL subscriber networks, in addition to the traditional structure of a radial-nodal type telephone network, it is envisaged to organize ring networks that ensure cable savings.

It can be assumed that in FOTS of the second generation, the amplification and conversion of signals in regenerators will occur at optical frequencies using elements and circuits of integrated optics. This will simplify the regenerative amplifier circuits, improve their efficiency and reliability, and reduce the cost.

In the third generation of FOTS, it is supposed to use the conversion of speech signals into optical ones directly with the help of acoustic transducers. An optical telephone has already been developed and work is underway to create fundamentally new automatic telephone exchanges that switch light, rather than electrical signals. There are examples of creating multi-position high-speed optical switches that can be used for optical switching.

On the basis of OK and digital transmission systems, an integrated multi-purpose network is being created, including various types of information transmission (telephony, television, data transmission of computers and automated control systems, video telephone, phototelegraph, transmission of newspaper pages, messages from banks, etc.). A digital PCM channel with a transmission rate of 64 Mbps (or 32 Mbps) was adopted as a unified one.

For the widespread use of QA and FOTS, it is necessary to solve a number of problems. These primarily include the following:

study of systemic issues and determination of technical and economic indicators of the use of OK on communication networks;
mass industrial production of single-mode fibers, light guides and cables, as well as optoelectronic devices for them;
increasing moisture resistance and reliability of OK through the use of metal shells and hydrophobic filling;
mastering the infrared wavelength range of 2...10 µm and new materials (fluoride and chalcogenide) for the manufacture of light guides that allow communication over long distances;
creation of local networks for computer technology and informatics;
development of testing and measuring equipment, reflectometers, testers necessary for the production of OK, configuration and operation of FOCL;
mechanization of laying technology and automation of OK installation;
improving the technology of industrial production of fiber light guides and OK, reducing their cost;
research and implementation of the soliton transmission mode, in which the pulse is compressed and the dispersion is reduced;
development and implementation of a system and equipment for spectral multiplexing of OK;
creation of an integrated subscriber network of multi-purpose;
the creation of transmitters and receivers that directly convert sound into light and light into sound;
increasing the degree of integration of elements and the creation of high-speed units of PCM channel-forming equipment using integrated optics elements;
creation of optical regenerators without converting optical signals into electrical ones;
improvement of transmitting and receiving optoelectronic devices for communication systems, development of coherent reception;
development of effective methods and devices for power supply of intermediate regenerators for zonal and backbone communication networks;
optimization of the structure of various sections of the network, taking into account the peculiarities of using systems on OK;
improvement of equipment and methods for frequency and time separation of signals transmitted through optical fibers;
development of a system and devices for optical switching.

Conclusion
At present, broad horizons have opened up for the practical application of OK and fiber-optic transmission systems in such sectors of the national economy as radio electronics, computer science, communications, computer technology, space, medicine, holography, mechanical engineering, nuclear energy, etc.

Fiber optics is developing in many directions, and without it, modern production and life are not possible.

The use of optical systems in cable television provides high image quality and significantly expands the possibilities of information service for individual subscribers.

Fiber-optic sensors are capable of operating in aggressive environments, are reliable, small in size and not subject to electromagnetic influences. They allow you to evaluate at a distance various physical quantities (temperature, pressure, current, etc.). Sensors are used in the oil and gas industry, security and fire alarm systems, automotive technology, etc.

It is very promising to use OK on high-voltage power lines (TL) for the organization of technological communications and telemechanics. Optical fibers are embedded in a phase or cable. Here, the channels are highly protected from the electromagnetic effects of power lines and thunderstorms.

The lightness, small size, non-flammability of OK made them very useful for the installation and equipment of aircraft, ships and other mobile devices.
Bibliography

Optical communication systems / J. Gower - M .: Radio and communication, 1989;
Communication lines / I. I. Grodnev, S. M. Vernik, L. N. Kochanovsky. - M.: Radio and communication, 1995;
Optical cables / I. I. Grodnev, Yu. T. Larin, I. I. Teumen. - M.: Energoizdat, 1991;
Optical cables of multichannel communication lines / A. G. Muradyan, I. S. Goldfarb, V. N. Inozemtsev. - M.: Radio and communication, 1987;
Fiber light guides for information transmission / J. E. Midwinter. - M.: Radio and communication, 1983;
Fiber-optic communication lines / II Grodnev. - M.: Radio and communication, 1990

The history of the emergence and development of power lines in Russia

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