MEANS OF COMMUNICATION:

DEVELOPMENT,

PROBLEMS,

PERSPECTIVES

MATERIALS

SCIENTIFIC AND PRACTICAL CONFERENCE

MUNICIPAL EDUCATIONAL INSTITUTION

"NOVOSELITSKAYA SECONDARY EDUCATIONAL SCHOOL"

NOVGOROD DISTRICT OF NOVGOROD REGION

The conference materials contain information from the simplest sound and visual means for transmitting signals and commands to the most modern ones. The historical path of development and improvement of means of communication, the role of scientists and practitioners, the latest achievements in physics and technology, their practical use are shown.

Lesson - conference promotes growth creativity teachers, the formation of students' skills independent work with various sources of information, allows you to comprehend previously acquired knowledge in a new light, systematize and generalize them. Participation in the conference develops the ability to speak publicly, listen and analyze the messages of their classmates.

The materials of the conference are designed for creative use and are intended for teachers to help in preparing and conducting lessons in physics.

FROM THE HISTORY OF COMMUNICATIONS

The means of communication has always played important role in the life of society. In ancient times, communication was carried out by messengers who transmitted messages orally, then in writing. Signal lights and smoke were among the first to be used. During the day, against the background of clouds, smoke is clearly visible, even if the fire itself is not visible, and at night - a flame, especially if it is lit on an elevated place. At first, only predetermined signals were transmitted in this way, say, "the enemy is approaching." Then, by arranging several smokes or fires in a special way, they learned to send whole messages.

Sound signals were used mainly over short distances to gather troops and the population. To transmit sound signals, the following were used: a beater (a metal or wooden board), a bell, a drum, a trumpet, a whistle and covers.

The veche bell in Veliky Novgorod played a particularly important role. At his call, Novgorodians gathered at a veche to resolve military and civil matters.

For command and control of the troops, banners of various shapes were of no small importance, on which large pieces of various bright-colored fabrics were fastened. The military leaders wore distinctive clothes, special headdresses and signs.

In the Middle Ages, flag signaling appeared, which was used in the fleet. The shape, color and design of the flags had a specific meaning. One flag could mean a sentence ("The ship is diving" or "I require a pilot"), and it, in combination with others, was a letter in a word.

From the 16th century in Rus', the delivery of information with the help of the Yamskaya chase became widespread. Yamsky tracts were laid to important centers of the state and border towns. In 1516, a yamskaya hut was created in Moscow to manage the post office, and in 1550 a yamskaya order was established - the central institution in Russia that was in charge of the yamskaya chase.

In Holland, where there were many windmills, simple messages were transmitted by stopping the wings of the mills in certain positions. This method has been developed in the optical telegraph. Towers were erected between cities, which were located at a distance of line of sight from each other. Each tower had a pair of huge jointed wings with semaphores. The telegraph operator received the message and immediately passed it on, moving the wings with levers.

The first optical telegraph was built in 1794 in France, between Paris and Lille. The longest line - 1200 km - operated in the middle of the 19th century. between Petersburg and Warsaw. The line had 149 towers. She was served by 1308 people. The signal along the line traveled from end to end in 15 minutes.

In 1832, an officer of the Russian army, physicist and orientalist Pavel Lvovich Schilling invented the world's first electric telegraph. In 1837 S. Morse developed and supplemented Schilling's idea. By 1850, the Russian scientist Boris Semenovich Jacobi created a prototype of the world's first telegraph apparatus with direct printing of received messages.

In 1876 (USA) he invented the telephone, and in 1895 a Russian scientist invented the radio. Since the beginning of the twentieth century. radio communications, radiotelegraph and radiotelephone communications began to be introduced.

Map of the Yamsky tracts of the 16th century. Russian postal routes of the 18th century.

COMMUNICATION CLASSIFICATION

Communication can be done by signals of various physical nature:

Sound;

Visual (light);

Electrical.

According With the nature of the signals used to exchange information means of transmission (reception) and delivery messages and documents communication can be:

Electrical (electrocommunications);

Signal;

Courier postal.

Depending on the linear means used and the signal propagation medium, communication is divided by gender on the:

Wired connection;

Radio communication;

Radio relay communication;

Tropospheric radio communication;

Ionospheric radio communication;

Meteor radio communication;

space communications;

optical communication;

Mobile communications.

According to the nature of the messages transmitted and mind communication is divided into;

telephone;

Telegraph;

Telecode (data transmission);

Facsimile (phototelegraph);

television;

video telephone;

Signal;

Courier post.

Communication can be done through transmission of information over communication lines:

plain text;

coded;

Encrypted (using codes, ciphers) or classified.

Distinguish duplex communication, when simultaneous transmission of messages in both directions is ensured and interruption (request) of the correspondent is possible, and simplex communication when the transmission is carried out alternately in both directions.

Communication happens bilateral, in which duplex or simplex information is exchanged, or unilateral, if there is a transmission of messages or signals in one direction without a return response or confirmation of the received message.

SIGNAL COMMUNICATION

Signaling communication carried out by transmitting messages in the form of predetermined signals using signaling means. IN Navy signal communication is used to transfer service information between ships, vessels and raid posts both in plain text and in signals typed in codes.

For signal communication by means of subject signaling, one-, two- and three-flag codes of signals of the Navy, as well as a flag semaphore, are usually used. To transmit plain text and signal combinations of arches with light-signal devices, signs of the Morse telegraphic alphabet are used.

Ships and ships of the Navy and offshore posts for negotiations with foreign ships, merchant ships and foreign coastal posts, especially on issues of ensuring the safety of navigation and security human life at sea, use the International Code of Signals.

Signal means, means of signal visual and sound communication, used to transmit short commands, reports, warnings, designations and mutual identification.

Visual means of communication are divided into: a) means of subject signaling (signal flags, figures, flag semaphore); b) means of light communication and signaling (signal lights, searchlights, signal lights); c) pyrotechnic means of signaling (signal cartridges, lighting and signal cartridges, marine signal torches).

Sound signaling means - sirens, megaphones, whistles, horns, ship's bells and foghorns.

Signal means have been used since the time of the rowing fleet to control ships. They were primitive (drum, lit fire, triangular and rectangular shields). Peter I, the creator of the Russian regular fleet, set up various flags and introduced special signals. 22 ship flags, 42 galley flags and several pennants were installed. With the development of the fleet, the number of signals also increased. In 1773, the signal book contained 226 reports, 45 night and 21 fog signals.

In 1779, a Russian mechanic invented a “spotlight” with a candle and developed a special code for transmitting signals. In the 19th - 20th centuries. further development was received by the means of light communication - lanterns and searchlights.

Currently, the flag table of the Naval Code of Signals contains 32 alphabetic, 10 numeric and 17 special flags.

PHYSICAL BASIS OF TELECOMMUNICATION

At the end of the 20th century, widespread telecommunication - the transmission of information by means of electrical signals or electromagnetic waves. Signals go through communication channels - wires (cables) or without wires.

All methods of telecommunication - telephone, telegraph, telefax, Internet, radio and television are similar in structure. At the beginning of the channel there is a device that converts information (sound, image, text, commands) into electrical signals. Then these signals are converted into a form suitable for transmission over long distances, amplified to the desired power and "sent" to the cable network or radiated into space.

On the way, the signals are greatly weakened, so intermediate amplifiers are provided. They are often built into cables and put on repeaters (from Latin re - a prefix indicating a repeated action, and translator - "carrier"), transmitting signals over land lines or via satellite.

At the other end of the line, the signals enter a receiver with an amplifier, then they are converted into a form convenient for processing and storage, and, finally, they are again converted into sound, image, text, commands.

WIRED COMMUNICATION

Before the advent and development of radio communications, wired communication was considered the main one. By purpose, wired communication is divided into:

Far - for inter-regional and inter-district communication;

Internal - for communication in locality, in industrial and service premises;

Service - to manage the operational service on communication lines and nodes.

Wired communication lines are often interfaced with radio relay, tropospheric and satellite lines. Due to its great vulnerability (natural influences: strong winds, snow and ice build-up, lightning strikes or human criminal activity), wired communication has disadvantages in application.

TELEGRAPH COMMUNICATION

Telegraph communication is used to transmit alphanumeric information. Auditory telegraph radio communication is the simplest type of communication, which is economical and noise-immune, but its speed is low. Direct-printing telegraph communication has a higher transmission rate and the ability to document received information.

In 1837 S. Morse developed and supplemented Schilling's idea. He proposed a telegraphic alphabet and a simpler telegraph apparatus. In 1884, the American inventor Morse put into operation the first writing telegraph line in the United States between Washington and Baltimore, 63 km long. Supported by other scientists and entrepreneurs, Morse achieved a significant distribution of his apparatus not only in America, but also in most European countries.

By 1850, Russian scientist Boris Semenovich Jacobi

(1801 - 1874) created a prototype of the world's first telegraph apparatus with direct printing of received messages.

The principle of operation of the writing electromagnetic telegraph apparatus is as follows. Under the action of current pulses coming from the line, the armature of the receiving electromagnet was attracted, and in the absence of current, it was repelled. A pencil was attached to the end of the anchor. In front of him, a matte porcelain or faience plate moved along the guides with the help of a clockwork.

During the operation of the electromagnet, a wavy line was recorded on the plate, the zigzags of which corresponded to certain signs. A simple key was used as a transmitter, closing and opening the electrical circuit.

In 1841, Jacobi built the first electric telegraph line in Russia between the Winter Palace and the General Staff in St. Petersburg, and two years later a new line to the palace in Tsarskoe Selo. Telegraph lines consisted of insulated copper wires buried in the ground.

During the construction of the Petersburg-Moscow railway, the government insisted on laying an underground telegraph line along it. Jacobi proposed to build an overhead line on wooden poles, arguing that it is impossible to guarantee the reliability of communication of such a long distance. As expected, this line, built in 1852, did not last even two years due to imperfect insulation and was replaced by an air line.

Academician carried out major works on electrical machines, electrical telegraphs, mine electrical engineering, electrochemistry and electrical measurements. He opened new way electroplating.

The essence of telegraph communication is the representation of a finite number of symbols of an alphanumeric message in the transmitter of a telegraph apparatus by the corresponding number of combinations of elementary signals that differ from each other. Each such combination, called a code combination, corresponds to a letter or number.

The transmission of code combinations is usually carried out by binary alternating current signals, most often modulated in frequency. When receiving, the electrical signals are converted back into characters and these characters are registered on paper in accordance with the accepted code combinations.

Telegraph communication is characterized by reliability, speed of telegraphy (transmission), reliability and secrecy of the transmitted information. Telegraph communication is developing in the direction of further improvement of equipment, automation of the processes of transmitting and receiving information.

TELEPHONE COMMUNICATIONS

Telephone communication is intended for conducting oral negotiations between people (personal or official). When driving complex systems Air defense, railway transport, oil and gas pipelines use operational telephone communication, which ensures the exchange of information between the central control point and controlled objects located at a distance of up to several thousand km. It is possible to record messages on sound recording devices.

The telephone was invented by an American on February 14, 1876. Structurally, Bell's telephone was a tube with a magnet inside. On the pole pieces it is put on a coil with a large number turns of insulated wire. A metal membrane is placed against the pole pieces.

Bell's handset was used to transmit and receive speech sounds. The subscriber's call was made through the same handset using a whistle. The range of the phone did not exceed 500 m.

A miniature color television camera equipped with a microlight turns into a medical probe. Introducing it into the stomach or esophagus, the doctor examines what he could previously see only during surgery.

Modern television equipment makes it possible to control complex and harmful productions. The operator-dispatcher on the monitor screen monitors several technological processes simultaneously. A similar task is solved by the operator-dispatcher of the traffic safety service, following the traffic flows on the roads and intersections on the monitor screen.

Television is widely used for surveillance, reconnaissance, control, communications, command and control, in weapon guidance systems, navigation, astro-orientation and astro-correction, for monitoring underwater and space objects.

IN rocket troops television allows you to monitor the preparation for launch and launch of missiles, monitor the state of units and assemblies in flight.

In the navy, television provides control and surveillance of the surface situation, review of premises, equipment and personnel actions, search and detection of sunken objects, bottom mines, and rescue operations.

Small-sized television cameras can be delivered to the reconnaissance area using artillery shells, radio-controlled unmanned aircraft.

Television has found wide application in simulators.

Television systems operating in conjunction with radar and direction-finding equipment are used to provide air traffic control services at airports, flights in adverse weather conditions and blind landing of aircraft.

The use of television is limited by insufficient range, dependence on weather conditions and illumination, and low noise immunity.

Trends in the development of television - expanding the range of spectral sensitivity, the introduction of color and surround television, reducing the weight and dimensions of the equipment.

VIDEO TELEPHONE COMMUNICATION

Videotelephone communication - the combination of telephone communication and slow-motion television (with a small number of scan lines) - can be carried out via telephone channels. It allows you to see the interlocutor and show simple still images.

FELDJEGERSKO - POSTAL SERVICE

Delivery of documents, periodicals, parcels and personal correspondence is carried out using courier and mobile communications: aircraft, helicopters, cars, armored personnel carriers, motorcycles, boats, etc.

CONNECTION QUALITY

The quality of communication is determined by the totality of its interrelated basic properties (characteristics).

Timeliness connections- its ability to ensure the transmission and delivery of messages or negotiation at a given time - is determined by the time of deployment of nodes and communication lines, the speed of establishing communication with the correspondent, the speed of information transfer.

Communication Reliability- its ability to work without fail (stably) for a certain period of time with the reliability, secrecy and speed specified for these operating conditions. The communication reliability is significantly affected by the noise immunity of the communication system, lines, channels, which characterizes their ability to function under the influence of all types of interference.

Communication reliability- its ability to ensure the reception of transmitted messages with a given accuracy, which is estimated by the loss of reliability, that is, the ratio of the number of characters received with an error to total number transferred.

In conventional communication lines, the loss of reliability is at best 10-3 - 10-4, so they use additional technical devices to detect and correct errors. In automated control systems of the developed countries of the world, the norm of reliability is 10-7 - 10-9.

Communication stealth characterized by the secrecy of the very fact of communication, the degree of detection hallmarks communication, secrecy of the content of transmitted information. The secrecy of the content of the transmitted information is ensured through the use of encryption equipment, encryption, and coding of transmitted messages.

PROSPECTS FOR THE DEVELOPMENT OF COMMUNICATIONS

At present, all kinds and types of communication and the corresponding technical means are being improved. In radio relay communication, new sections of the microwave frequency range are used. In tropospheric communications, measures are taken against communication disruptions due to changes in the state of the troposphere. Space communications are being improved on the basis of "stationary" relay satellites with multiple access equipment. Receives development and practical use optical (laser) communication primarily for the transmission of large amounts of information in real time between satellites and spacecraft.

Much attention is paid to the standardization and unification of blocks, assemblies and elements of equipment for various purposes in order to create unified communication systems.

One of the main directions for improving communication systems in developed countries is to ensure the transmission of all types of information (telephone, telegraph, facsimile, computer data, etc.) in a converted discrete-pulse (digital) form. Digital communication systems have great advantages in the creation of global communication systems.

LITERATURE

1. Computer science. Encyclopedia for children. Volume 22. M., "Avanta +". 2003.

2. At the origins of television. The newspaper "Physics", No. 16 for 2000

3. Craig A., Rosni K. Science. Encyclopedia. M., Rosman. 1994.

4. Kyandskaya-, On the question of the world's first radiogram. The newspaper "Physics", No. 12 for 2001

5. Morozov invented and for which G. Marconi received a patent. The newspaper "Physics", No. 16 for 2002

6. MS - DOS - no question! Editing and publishing center "Tok". Smolensk. 1993.

7. Reid S., Farah P. History of discoveries. M., Rosman. 1995.

8. Soviet military encyclopedia. M., Military publishing house of the Ministry of Defense. 1980.

9. Technique. Encyclopedia for children. Volume 14. M., "Avanta +". 1999.

10. Turov military connection. Volume 1,2,3. M., Military publishing house. 1991.

11. Wilkinson F., Pollard M. Scientists who have changed the world. M., "Word". 1994.

12. Urvalov television equipment. (ABOUT). The newspaper "Physics", No. 26, 2000

13. Urvalov electronic television. The newspaper "Physics", No. 4, 2002

14. Fedotov schemes by O. Lodge and G. Marconi. The newspaper "Physics", No. 4, 2001

15. Physics. Encyclopedia for children. Volume 16. M., "Avanta +". 2000.

16. Hafkemeyer H. Internet. Journey through the worldwide computer network. M., "Word". 1998.

17. At the origins of radar in the USSR. M., "Soviet radio". 1977.

18. Shmenk A., Vetien A., Kete R. Multimedia and virtual worlds. M., "Word". 1997.

Foreword ... 2

From the history of communications ... 3

Communication classification … 5

Signal communication … 6

The physical basis of telecommunications ... 7

Wired … 7

Telegraph communication ... 8

Telephony … 10

Telecode communication … 12

Internet … 12

Optical (laser) communication … 14

Fax … 14

Radio communication ... 15

Radio relay communication … 17

Tropospheric communications … 17

Ionospheric radio communication ... 17

Meteor radio communication ... 17

Space communications … 18

Radar … 18

Television communications ... 21

Video telephony … 24

Courier-postal communication ... 24

Communication quality … 25

Prospects for the development of communications ... 25

Literature ... 26

Responsible for release:

Computer layout: Press Boris

ELECTRONIC COMMUNICATIONS
the technique of transmitting information from one place to another in the form of electrical signals sent over wires, cables, fiber optic lines, or no guide lines at all. Directed transmission over wires is usually carried out from one specific point to another, as, for example, in telephony or telegraphy. Omnidirectional transmission, on the contrary, is usually used to transfer information from one point to many other points scattered in space, i.e. for broadcast purposes. Broadcasting is an example of non-directional transmission. The transmission of signals over wires can be considered as the flow of electric current through a wire, which is interrupted or changed in any way, from a transmitter located at one of the points in the network. This interruption or change in current detected by the receiver at another point in the network is the signal or piece of information sent by the transmitter. The transmission of information through radio or optical (light) waves is an electromagnetic radiation that can propagate without needing any medium, i.e. capable of propagating in a vacuum. Such transmission is carried out as a result of fluctuations in electric and magnetic fields. Radio and television waves, microwaves, infrared rays, visible light, ultraviolet rays, X-rays and gamma rays are all electromagnetic radiation. Each type of electromagnetic radiation is characterized by its own oscillation frequency, with radio waves corresponding to the low-frequency end of the spectrum, and gamma rays to the high-frequency end.
see also ELECTROMAGNETIC RADIATION . Although, in principle, signals can be transmitted by electromagnetic radiation of any frequency, not all parts of the electromagnetic spectrum are suitable for communication purposes, since the atmosphere is opaque for some wavelengths. The range of "radio frequencies" used is between about 1 and 30,000 MHz. In this range, AM broadcasts are broadcast at frequencies from 0.5 to 1.5 MHz, while FM and television broadcasts are broadcast over a much wider frequency range, the middle of which falls at 100 MHz. Microwave signals, including those sent to and received from communication satellites, are in the range from 4000 to 14000 MHz and even higher. Generally speaking, any signal needs a specific bandwidth or range of frequencies; the more complex the signal, the wider the required bandwidth. For example, a television signal, due to its much greater complexity, requires a bandwidth that is about 600 times greater than that of a voice signal. The entire used spectrum of radio frequencies allows placing 10 million speech or about 10,000 television channels in it. This spectrum is shared between broadcasters, emergency services, aviation, ships, mobile telephony, military and other users.
Revolution in the field of communication. IN recent decades electronic communications have developed so rapidly that the words "revolution in the field of communications" do not seem to be an exaggeration. The basis for many innovations was the rapid progress of electronic engineering and technology. In the early 1950s, a device called the transistor was developed. This miniature electronic component, made of semiconductor materials, is used to amplify or control electric current. Because transistors are smaller and more durable than vacuum tubes, they replaced tubes in radios and became the basis of computers.
see also ELECTROVACUUM AND GAS DISCHARGE DEVICES; TRANSISTOR.

In the late 1960s, instead of transistor circuits, computers began to use fully assembled semiconductor circuits, called integrated circuits (ICs). Subsequently, on a single silicon wafer, the size of which was only slightly larger than the size of the first transistor, technologists learned how to manufacture hundreds of thousands of transistors at once in a single process. This method, called large-scale integrated circuit (LSI) technology, allows many ICs to be placed in one small device.
see also INTEGRATED CIRCUIT . Each stage of the development of electronics was accompanied by a significant increase in the reliability of electronic components. At the same time, it was also possible to significantly reduce the size, power consumption and cost of many types of electronic equipment. The widespread use of technology such as computers, lasers, fiber optic lines, communication satellites, direct dial telephones, video telephones, transistor radios, and cable television has led to a complete overhaul of the traditional classification of communication methods. Nowadays, wire transmission is practically not identified with direct address communication, and wireless transmission with radio broadcasting. Probably the most powerful influence on the development of communication technology was the significant increase in the capacity of communications both over the air and by wire. This increased bandwidth is used for the ever-increasing global traffic of television, telephony and digital information.
Laser. One of the factors that played an important role in increasing the capacity of communication systems was the discovery of the laser in 1961. A laser is a light source that generates a narrow beam of high intensity light. Such a beam can be used to transmit signals. The unique feature of a laser is that it emits light of a single frequency, i.e. produces purely monochromatic radiation. Thus, a laser can serve as a generator of very high frequency (VHF) electromagnetic waves, similar to how a radio transmitter can serve as a source of lower frequency waves (radio waves). Since the frequency range of light waves (approximately from 5x108 to 109 MHz) is many times wider than the frequency range of radio waves, a light beam can transmit huge amounts of information. This part of the electromagnetic spectrum is wide enough to accommodate 80 million TV channels or 50 billion simultaneous telephone conversations. In practical communication technology, laser signals of a slightly lower frequency (infrared radiation) are transmitted from point to point over low-loss fiber optic lines. An optical cable contains from 10 to 100 or more optical fibers, each of which can provide the transmission of a television signal or the operation of many hundreds of telephone channels. Lasers are also used to transmit signals between military satellites. The lasers used in communications are tiny semiconductor devices, similar to light emitting diodes (LEDs) used in the digital displays of pocket calculators and watches. see also LASER ; QUANTUM GENERATORS AND AMPLIFIERS.
Communication satellites. The first communication satellites, placed in near-Earth orbits in the early 1960s, carried passive-type equipment and served only as signal repeaters.
see also COMMUNICATION SATELLITE. Modern communications satellites are usually launched into a geostationary orbit at an altitude of 35,900 km above the Earth's surface. Each satellite has 10 or more microwave receivers and transmitters. A modern satellite makes it possible to transmit several television programs across the oceans to entire continents and to ensure the operation of more than tens of thousands of telephone channels.
Cables. During World War I, communications engineers developed a method of using a pair of wires to transmit multiple telephone conversations at the same time. This method, called frequency multiplexing of channels, is based on the ability to transmit a wide range of audio frequencies over a pair of wires. In this case, the signals of each of the multiple transmitters are spread in frequency (using modulation) and the resulting higher frequency combined signal is transmitted to the receiving terminal, where it is separated into component signals by demodulation. A telephone cable with a protective sheath can contain from tens to hundreds of twisted wire pairs, each of which allows up to 24 telephone channels to operate. However, cables consisting of wire pairs have certain limitations. Above a certain frequency, signals transmitted over one pair begin to interfere with the signals of an adjacent pair. To solve this problem, a new type of transmission medium was developed - coaxial cable. Such a cable, containing 22 coaxial pairs, can provide simultaneous operation of 132,000 telephone channels. Each pair in such a cable is a central wire enclosed in a tube of the second conductor. The center conductor and the tube are electrically isolated from each other.
TASI. Time Division Multiplexing of Speech Interpolation (TASI) is a technique that doubles the capacity of transoceanic telephone cables by taking advantage of natural pauses in conversations. The two-way communication channel is idle for about 60% of the time during pauses in the conversation, as well as while the user is receiving. The TASI equipment, using a high-speed switch, provides unused time of one channel to any of the other users. Such a switch returns the channel to the user as soon as he starts talking, and disconnects him immediately after silence, providing the channel in pauses to other subscribers.
Pulse code modulation. This method of signal transmission by means of digital technology is especially convenient when using LSI and VLSI, as well as fiber optic lines. Such digital (PCM) transmission of voice and TV signals will eventually replace other means of communication. When using pulse code modulation, speech or image signals can be divided into many small time intervals; at each interval, a series of pulses of constant amplitude represents a signal. These pulses are sent to the receiving station instead of the original signals. One of the advantages of PCM is related to the fact that discrete electronic pulses of constant amplitude are easily distinguished from random noise of arbitrary amplitude (electrostatic origin), which are present to one degree or another in any transmission medium. Such pulses can be transmitted substantially uninterrupted by ambient noise since they are easy to separate. PCM is used for a wide variety of signals. Telegraph and facsimile messages, as well as other data that was previously sent over telephone lines by other methods, can be transmitted much more efficiently in a pulsed form. The traffic of such non-speech signals is constantly increasing; there are also systems that allow the transmission of mixed signals of speech, data and video information.
Electronic switching. Another innovation that has made telephony more efficient is electronic switching. The modern microcircuits described above made it possible to use electronic switches instead of mechanical ones at the PBX, which increased the speed and reliability of making calls. New switching systems are digital systems that use fast and compact LSIs to switch data, PCM signals or digital video signals. In addition to being well suited to various telephony applications, electronic switching allows for a number of innovations. These include: automatic transfer of a call to another number when the number of this subscriber is busy; speed dialing, in which the subscriber dials only one or two digits to connect to frequently called numbers; call signals, which notify the user that another subscriber is trying to connect with him.
Phones-computers. The telephone of the future will be used not only for ordinary communication. Telephone sets with built-in miniature and inexpensive logic circuits will be able to perform complex electronic functions. With the help of a PBX, such a phone can become an individual computer. By pressing the keys of his telephone, the user will be able to enter the data he wants to store, process information, request data from some central file, or perform calculations.
Videophone. New means of electronics make it possible to supplement sound information transmitted by telephone with images. Video transmissions between conference rooms located in several cities are used in order to avoid the need to move conference participants. Video broadcasts have begun to be widely used for teaching - lectures are transferred from one audience to another (remote) and recorded on videotape for use for the same purposes.
Cable television systems. Although laser radiation and millimeter waves can be used for broadcasting, limitations due to atmospheric absorption and other types of interference can only be overcome at great expense. Therefore, when looking for ways to expand broadcasting to avoid the limitations associated with the use of electromagnetic radiation, cable systems are increasingly being used. Cable television requires cabling from transmitters to receivers located in homes, for example. The radio listener or cable broadcast viewer does not experience the inconvenience of fading, ghosting and other interference. In addition, due to the fact that the number of channels transmitted via cable is practically unlimited (whereas a conventional TV broadcaster transmits only one program at a time), the viewer is provided with a much wider choice of programs. In the future, the media may become personalized information services capable of transmitting pre-recorded programs at the request of individual viewers. Community cable television (CATV) systems have been in operation for many years. Originally intended to serve remote communities where rooftop antennas did not provide good signal reception, CATV systems are also widely used in cities where interference is a problem.
The computer as an intelligent assistant. Specialists in the field computer science believe that eventually people will be able to spread their ideas more effectively through computers than through direct conversation. Usually the purpose of the conversation is to exchange, compare and critically discuss ideas already formed in the minds of the participants in the conversation. Ideas are mostly expressed in words, but if the subject of discussion is complex or has technical specifics, then graphics, photographs and calculations have to be used. The conversation does not always lead to full understanding, since the concepts being expressed can not be easily expressed in words; often they contain data and associations that are linked together in such a complex way that even the speaker finds it difficult to fully understand and express them. The listener, on the other hand, is unable to examine the way the speaker thinks and must rely on the information that he provides, and with a degree of inadequacy that is difficult to assess. The computer, according to cybernetics, provides the participant of the conversation with the opportunity to better understand the ideas of his interlocutor. A computer is an information processing machine that can store data, know where to find it, be able to compare it, sort it, compress it, or restructure it, and then display it on the screen in the most appropriate form. If information is entered into the computer that is related to the formulation of a certain idea, but did not sound clear enough when the interlocutor explained this idea, then the output of the computer can be obtained general idea about the speaker's way of thinking. Thus, the basic information of the speaker is available to the listener. In addition, the listener may need a computer to sort the data to reveal facts relevant to the problem or concept being discussed. Discussions can then take place between two or more interlocutors whose computers are connected so that information is collected, processed and exchanged so efficiently that solutions and creative ideas can emerge to a degree and at a level that could not be achieved without the use of computers. Experiments carried out in this direction have given encouraging results.
see also
INTELLIGENCE ARTIFICIAL;
OFFICE EQUIPMENT AND OFFICE EQUIPMENT;
TELEPHONE ;
COMPUTER ;
INFORMATION ACCUMULATION AND SEARCH;
RADIO AND TELEVISION ;
FIBER OPTICS ;
COMMUNICATION SATELLITE ;
TELEMETRY ;
SEMICONDUCTOR ELECTRONIC DEVICES .
LITERATURE
Ignatov V.A. Theory of information and signal transmission. M., 1979 Levin L.S., Plotkin M.A. Digital information transmission systems. M., 1982 Enderline R. Microelectronics for everyone. M., 1989 Apokin I., Maistrov L. History of computer technology. M., 1990

Collier Encyclopedia. - Open society. 2000 .

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Payment means presented and circulated in electronic form, the turnover of which guarantees the anonymity of the parties involved in the settlements: non-cash settlements between sellers and buyers, banks and their customers, carried out through ... ... encyclopedic Dictionary economics and law

Technical means used to carry out the experimental part of the measurements and having normalized metrological properties. To S. and. include Measures, measuring instruments (See Measuring instrument), measuring transducers ... ... Great Soviet Encyclopedia

"This new development of technology brings unlimited possibilities for good and evil"

It's only begining...

Since ancient times, mankind has been looking for and improving the means of information exchange. For short distances, messages were transmitted by gestures and speech, for long distances, with the help of bonfires located from each other within line of sight. Sometimes a chain of people lined up between the points and the news was transmitted by voice along this chain from one point to another. In central Africa, tom-tom drums were widely used to communicate between tribes.

Ideas about the possibility of transferring electric charges over distances and about the implementation of telegraph communication in this way were expressed with mid-eighteenth century. Professor of the University of Leipzin Johann Winkler - it was he who improved the electrostatic machine, proposing to rub the glass disc not with hands, but with silk and leather pads - wrote in 1744: "With the help of an insulated suspended conductor, it is possible to transfer electricity to the ends of the world at the speed of a bullet" . In the Scottish magazine "The Scot" s Magazine "on February 1, 1753, an article appeared, signed only by Ch.M. (later it turned out that its author was Charles Morison, a scientist from the city of Renfrew), in which a possible telecommunication system was first described It was proposed to hang as many uninsulated wires between two points as there are letters in the alphabet.Attach the wires at both points to glass racks so that their ends hang down and end with elderberry balls, under which, at a distance of 3-4mm, place the letters written on pieces of paper. at the point of transmission by the conductor of the electrostatic machine of the end of the wire corresponding to the required letter, at the point of reception, the electrified elderberry ball would attract a piece of paper with this letter.

In 1792, the Genevan physicist Georges Louis Lesage described his project of an electrical communication line based on laying 24 bare copper wires in a clay pipe, inside which every 1.5 ... 2 m partitions-washers made of glazed clay or glass with holes would be installed for wires. The latter, thus, would maintain a parallel arrangement, without touching each other. According to one unconfirmed, but very likely version, Lesange in 1774 at home carried out several successful experiments on telegraphy according to the Morison scheme - with electrification of elderberry balls that attract letters. The transmission of one word took 10...15 minutes, and the phrase 2...3 hours.

Professor I. Beckmann from Karlsruhe wrote in 1794: “The monstrous cost and other obstacles will never seriously recommend the use of an electric telegraph.

And just two years after this notorious "never", according to the project of the Spanish physician Francisco Savva, military engineer Augustine Betancourt built the world's first electric telegraph line 42 km long between Madrid and Aranjuez.

The situation repeated itself a quarter of a century later. Since 1794, from the beginning in Europe, and then in America, the so-called semaphore telegraph, invented by the French engineer Claude Chappe and even described by Alexandre Dumas in the novel The Count of Montecristo, has become widespread. High towers with poles such as modern antennas with movable crossbars were built on the line at a line of sight (8 ... 10 km), the relative position of which denoted a letter, syllable or even a whole word. At the transmitting station, the message was encoded, and the crossbars were alternately installed in the desired positions. Telegraph operators of subsequent stations duplicated these provisions. Two shifts were on duty at each tower: one received the signal from the previous station, the other transmitted it to the next station.

Although this telegraph served mankind for more than half a century, it did not satisfy the needs of society for fast communication. It took an average of 30 minutes to send one mail. Inevitably, there were interruptions in communication during rains, fogs, and blizzards. Naturally, the "eccentrics" were looking for more advanced means of communication. The London physicist and astronomer Francis Ronalds in 1816 began to conduct experiments with an electrostatic telegraph. In his garden, in the suburbs of London, he built a 13-kilometer line of 39 bare wires, which were suspended by means of silk threads on wooden frames installed every 20 m. Part of the line was underground - into a trench 1.2 m deep and 150 m long was a wooden tarred chute was laid, at the bottom of which there were glass tubes with copper wires passed through them.

In 1823 Ronalds published a pamphlet outlining his results. By the way, it was the world's first printed work in the field of electrical communications. But when he offered his telegraph system to the authorities, the British Admiralty declared: "Their lordships are quite satisfied with the existing telegraph system (semaphore described above) and do not intend to replace it with another."

Literally a few months after the discovery by Oersted of the effect of an electric current on a magnetic needle, the baton for the further development of electromagnetism was picked up by the famous French physicist, theorist, Andre Ampère, the founder of electrodynamics. In one of his communications to the Academy of Sciences in October 1820, he was the first to put forward the idea of ​​an electromagnetic telegraph. "The possibility has been confirmed," he wrote, "to force the magnetized needle, located at a great distance from the battery, to move with the help of a very long wire." And further: "It would be possible ... to transmit messages by sending telegraph signals in turn along the corresponding wires. In this case, the number of wires and arrows should be taken equal to the number letters in the alphabet. At the receiving end, there should be an operator who would write down the transmitted letters, observing the deviating arrows. If the wires from the battery are connected to a keyboard, the keys of which would be marked with letters, then telegraphy can be carried out by pressing the keys. The transmission of each letter would only take the time it takes to press the keys on the one hand and read the letter on the other.

Not accepting the innovative idea, the English physicist P. Barlow wrote in 1824: “At the earliest stage of experiments with electromagnetism, Ampère suggested creating an instantaneous telegraph using wires and compasses. However, the assertion was doubtful ... that it would be possible to carry out this project with wire up to four miles (6.5 km) long. The experiments I made found that a noticeable weakening of the action occurs even with a wire length of 200 feet (61 meters), and this convinced me of the impracticability of such a project. "

And just eight years later, Corresponding Member Russian Academy Sciences Pavel Lvovich Schilling embodied Ampere's idea into a real design.

The inventor of the electromagnetic telegraph, P. L. Schilling, was the first to understand the complexity of manufacturing reliable underground cables at the dawn of electrical engineering and proposed the ground part of the cable projected in 1835-1836. make the telegraph line aerial by hanging an uninsulated bare wire on poles along the Peterhof road. It was the world's first overhead line project. But members of the government's "Committee for the Consideration of the Electromagnetic Telegraph" rejected Schilling's project, which seemed fantastic to them. His proposal was met with unfriendly and derisive exclamations.

And 30 years later, in 1865, when the length of telegraph lines in European countries was 150,000 km, 97% of them were air suspension lines.

Telephone.

The invention of the telephone belongs to a 29-year-old Scot, Alexander Graham Bell. Attempts to transmit sound information by means of electricity have been made since the middle of the 19th century. Almost the first in 1849 - 1854. The mechanic of the Parisian telegraph Charles Boursel developed the idea of ​​telephoning. However, he did not translate his idea into a working device.

Since 1873, Bell has been trying to design a harmonic telegraph, trying to achieve the ability to transmit seven telegrams simultaneously on one wire (according to the number of notes in an octave). He used seven pairs of flexible metal plates, similar to a tuning fork, with each pair tuned to a different frequency. During experiments on June 2, 1875, the free end of one of the plates on the transmitting side of the line was welded to the contact. Bell's assistant mechanic Thomas Watson, unsuccessfully trying to fix the malfunction, cursed, perhaps even using not quite normative vocabulary. Located in another room and manipulating the receiving plates, Bell, with his sensitive trained ear, caught the sound that came through the wire. Spontaneously fixed at both ends, the plate turned into a kind of flexible membrane and, being above the pole of the magnet, changed it magnetic flux. As a result, the incoming line electricity changed according to the fluctuations in the air caused by Watson's muttering. This was the birth of the telephone.

The device was called the "Bell tube". It should be applied alternately to the mouth, then to the ear, or use two tubes at the same time.

Radio.

May 7 (April 25 old style) 1895 happened historical event, which was appreciated only a few years later. At a meeting of the Physics Department of the Russian Physical and Chemical Society (RFCS), the teacher of the Mine Officer Class, Alexander Stepanovich Popov, made a report "On the relationship of metal powders to electrical vibrations." During the report of A.S. Popov demonstrated the operation of the device he created, designed to receive and register electromagnetic waves. It was the world's first radio receiver. He sensitively reacted with an electric call to parcels. electromagnetic oscillations, which were generated by the Hertz vibrator.

STRUCTURE AND ORGANIZATION OF MOBILE COMMUNICATIONS

Discipline of specialization of the specialty 200700 - Radio engineering

Graduating department "High-frequency means of radio communication and television"

The course was developed and taught by Associate Professor of the Department of HCRT, Ph.D. S.N. Shabunin

Goals and objectives of the discipline

The purpose of teaching the discipline "Structure and organization of mobile communications" is to study by students the current state of mobile radio communications, the architecture and functioning of paging systems, trunking and cellular communications, satellite communications systems.

Peculiarities of radio wave propagation in urban conditions, ways to improve the quality of radio channels are considered.

Requirements for the level of mastering the content of the discipline

The study of the discipline "Structure and organization of mobile communications" requires knowledge of previously read courses "Device for generating and generating signals", "Device for receiving and processing signals", "Antennas and microwave devices", "Electrodynamics and propagation of radio waves", "Digital devices and microprocessors" .

IN as a result of studying the discipline, students should:

have an idea about the main communication standards and the structure of networking;

be able to predict the passage of radio waves in mobile communication systems of various types;

choose a frequency plan for building communication networks;

calculate the number of users in a network cell;

choose for specific conditions the optimal scheme for organizing mobile radio communications.

1. Zakirov S.G. Cellular communication of the GSM standard. Current state, transition to third generation networks / S.G. Zakirov, A.F. Nadev, R.R. Faizullin. M.: Eco-Trend. 2004. 264 p.

2. Gromakov Yu.A. Standards and systems of mobile radio communication / Yu.A. Gromakov. M: Eco-Trend. 2000 240 p.

3. Andrianov V.I. Mobile communications. IN AND. Andrianov, A.V. Sokolov. St. Petersburg: BHV-St. Petersburg, 1998. 256 p.

4. Burnev V.B. Electronic textbook on the system of cellular communication with time division of channels of the GSM standard.http://study.ustu.ru/view/aid_view.aspx?AidId=50

5. Burnev V.B. Electronic Toolkit to study the standard of the cellular communication system IS-95c (CDMA-2000 1x). http://study.ustu.ru/view/aid_view.aspx?AidId=47

6. Antenna-feeder devices of land mobile communication systems / Ed. A.L. Buzova. M.: Radio and communication. 1997. - 150 p.

7. Ratynsky M.V. Fundamentals of cellular communications / M.V. Ratynsky. M: Radio and communications. 2000. 248 p.

8. The Free Encyclopedia http://en.wikipedia.org/wiki/GSM

9. The Free Encyclopedia http://en.wikipedia.org/wiki/Cdma

10. http://sabitov.pochta.ru/html/glava2.htm#General%20information

11. The Free Encyclopedia

http://en.wikipedia.org/wiki/Nordic_Mobile_Telephone

1. HISTORY OF THE DEVELOPMENT OF COMMUNICATIONS ..............................................................
2. PERSONAL RADIO COMMUNICATION .................................................................................. ................................................. ...
2.1. WITH PERSONAL CALLING SYSTEMS.....................................................................................................................
2.2. WITH TUNING SYSTEMS..........................................................................................................................
2.3. WITH CELLULAR COMMUNICATION SYSTEMS....................................................................................................................................
2.4. WITH SATELLITE COMMUNICATION SYSTEMS...........................................................................................................................
3. PERSONAL CALLING SYSTEMS .............................................................. ................................................. ...........
3.1. WITH METHOD FOR FORMING A WORKING AREA:.............................................................................................................
3.2. WITH STRUCTURE OF THE PACING NETWORK..........................................................................................................
3.3. F FUNCTIONAL PAGER SCHEME..................................................................................................................
3.4. WITH CODING STANDARDS IN PERSONAL CALL SYSTEMS.................................................................
4. CELLULAR MOBILE COMMUNICATION SYSTEMS .............................................................. ................................................. ..
4.1. WITH METHOD OF DIVISION OF THE TERRITORY INTO CELLS.............................................................................................................
4.2. T RI GENERATIONS OF MOBILE RADIO COMMUNICATION SYSTEMS.........................................................................................
5. ANALOGUE CELLULAR COMMUNICATIONS .............................................................. .................................................
5.1. A CELLULAR TAX SYSTEM NMT-450 ............................................... ...............................................
5.2. INCOMING CALL SETUP - BASE STATION TO MOBILE ................................................
5.3. OUTGOING CALL SETUP - MOBILE TO BASE ..............................................
5.4. ABOUT ORGANIZATION OF CONNECTIONS AND PRINCIPLES OF ADDRESSING SUBSCRIBERS.................................................................
5.5. WITH STANDARD WORKING FRAME STRUCTURE NMT ............................................... ................................................
5.6. E MOBILE STATION STAFET TRANSMISSION.................................................................................................
6. DIGITAL CELLULAR COMMUNICATION STANDARDS.................................................................. ................................................. .
6.1. GSM (GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS) .............................................. .........................................
6.1.1. Basic elements of a GSM network .............................................................. ................................................. ................
6.1.2. System operation .................................................................. ................................................. ...................
6.1.3. Checking the legality of the operation of the mobile station .............................................. .................................
6.1.4. Temporary frame structure .................................................................. ................................................. .................
6.1.5. Working time intervals (slots).................................................. ................................................. ........
6.1.6. Characteristics of the signal envelope .......................................................... ................................................. .....
6.1.7. Frequency hopping mode............................................................... ................................................. .................
6.1.8. Logical channels in the GSM standard.................................................... ................................................. ......
6.1.9. Structure of logical control channels .......................................................... ...............................................
6.1.10. Speech processing in the GSM standard .............................................. ................................................. ........
6.1.11. Channel coding .................................................................. ................................................. .........................
6.1.12. Radio signal modulation .................................................................. ................................................. .......................
6.1.13. Ensuring security in GSM .............................................................. ................................................. .........
6.1.14. Authentication mechanisms.................................................................... ................................................. ...............
6.1.15. Confidentiality of data transmission .................................................................. ................................................. .............
6.1.16. Prospects for GSM................................................... ................................................. .................................
6.2. WITH COMMUNICATION SYSTEMS WITH NOISE-LIKE SIGNALS..........................................................................................
6.2.1. DSSS (Direct Sequence Spread Spectrum) .................................................... ................................................. ......
6.2.2. MC-CDMA (Multi Carrier - CDMA).................................................. ................................................. ................
6.2.3. FHSS (Frequency Hopping Spread Spectrum) .................................................... ..................................................
6.2.4. CDMA (IS-95) cellular communication system .......................................... ................................................. .........
6.2.5. Traffic and control channels .......................................................... ................................................. .................
6.2.6. Direct Channels in CDMA IS-95............................................... ................................................. ...................
6.2.7. Forward channel coding .................................................................. ................................................. .................
6.2.8. Back channel coding .................................................................. ................................................. ..............
6.2.9. Signal conditioning by the base station............................................................... ..................................................
6.2.10. Signal conditioning by the base station............................................................... ...............................................
6.2.11. Power management .................................................................. ................................................. .........................
6.2.12. Formation of a QPSK signal............................................... ................................................. ................
6.2.13. Speech coding .................................................................. ................................................. ...................................

6.2.14. Combating multipath .............................................................. ................................................. ....................
6.2.15. Organization of the handover .............................................................. ................................................. ......
6.2.16. Security Aspects in IS-95............................................................... ................................................
6.2.17. Prospects for CDMA.............................................. ................................................. ...............................
7. RADIO WAVE PROPAGATION IN MOBILE COMMUNICATIONS.................................................................. .........................
7.1. R RADIO WAVES PROPAGATION IN FREE SPACE........................................................................
7.2. T RI OF THE MAIN METHODS OF RADIO WAVE PROPAGATION.............................................................................
	ABOUT RADIO WAVE REFLECTION ............................................................... ................................................. ......................
	D IFRACTION OF RADIO WAVES ............................................... ................................................. .........................
	SCATTERING OF RADIO WAVES ............................................... ................................................. .........................
7.3. MODELS FOR CALCULATION OF SIGNAL REDUCTION IN RADIO CHANNELS BASED ON EXPERIMENTAL
	.....................................................................................................................................................................
8. MULTI-STATION ACCESS TECHNIQUE.................................................................. .........................................
8.1. METHODS .................................................. ................................................. ....................... COMMUNICATION ORGANIZATIONS
8.2. FROM FREQUENCY DIVISION MULTIPLE ACCESS - FDMA SYSTEMS
8.3. FROM THE SYSTEM .................... TIME DIVISION MULTIPLE ACCESS - TDMA
8.4. FROM THE SYSTEM ................................ MULTIPLE ACCESS WITH EXPANDED FREQUENCY SPECTRUM
8.5. FROM THE SYSTEM ........................ FHMA MULTIPLE ACCESS
8.6. FROM THE SYSTEM ........................ CODE DIVISION MULTIPLE ACCESS - CDMA
8.7. COMPARISON .................................................. ......................................... CELLULAR COMMUNICATION NETWORKS BETWEEN THEM
9. SATELLITE............................................... ...........................PERSONAL COMMUNICATION SYSTEMS
9.1. ORGANIZATION .................................................... ................................................. ...................................... CONTACTS
9.2. H ISCOORBITAL................................................. ............................................... IRIDIUM COMMUNICATION SYSTEM
9.3. H ISCOORBITAL................................................. ...................................... GLOBAL STAR COMMUNICATION SYSTEM
9.4. GEOSTATIONAL ............................................................... ......................................... INMARSAT COMMUNICATION SYSTEM
10. ENVIRONMENTAL............................... ASPECTS OF THE USE OF MOBILE COMMUNICATIONS A
11. CONCLUSION............................................... ................................................. ................................................. ..
12. RESOLUTION............................................................... ................................................. ............................. EXERCISES

1. HISTORY OF DEVELOPMENT OF COMMUNICATIONS

The first mention of the transmission of information over a distance is found in the ancient Greek myth of Theseus. The father of this hero, Aegeus, sending his son to battle with the monster Minotaur, who lived on the island of Crete, asked his son, if successful, to raise a white sail on the returning ship, and in case of defeat - black. Theseus killed the Minotaur, but the sails, as always, were mixed up, and the unfortunate father, thinking that the monster had lifted his son, drowned himself. In honor of this event, the sea where the child-loving Aegeus drowned himself still bears the name Aegean. Drums, fire smoke, church bells were used to transmit messages, but such messages were not very informative.

The first communication system, called the telegraph, was invented by the Frenchman Claude Chappe (1763-1805) at the end of the 18th century. The first line was between Paris and Lyon. She worked as follows. Towers were built on the tops of the hills, on which special structures were installed with two long planks that changed their position. Each of the 49 positions corresponded to a letter or number. By the middle of the 19th century, the length of the lines had increased to 4828 km and the system worked quite successfully.

The next major step towards improving the means of communication was the appearance of the electric telegraph by Wilman Cook (1806 - 1879) and Charles Winston (1802 - 1875). Electrical signals were sent through wires that actuated arrows that pointed to various letters.

In 1843, American Samuel Morse (1791 - 1872) invented a new telegraph code that replaced the code of Wilman Cook and Charles Winston. Signals were transmitted in the form of dots and dashes. The reliability and accuracy of message transmission has increased significantly. Morse code is still used today.

The inventor of the telephone is Alexander Graham Bell, who on March 7, 1876 patented a method for transmitting sound by telegraph.

On April 25, Old Style (May 7, New Style), 1895, Alexander Stepanovich Popov, for the first time in the world, made a report for the scientific and technical community on the method he invented for using radiated electromagnetic waves for wireless transmission of electrical signals containing information useful to the recipient, and demonstrated such transfer in action. In March of the following year, he demonstrated a signal transmission device, transmitting a radiogram of their two words "Heinrich Hertz" to a distance of 250 m.

The first radiotelephone communication system, offering services to everyone, began its operation in 1946 in St. Louis (USA). The radiotelephones used in this system used conventional fixed