Transcript

1 FEDERAL COMMUNICATIONS AGENCY State educational institution of higher professional education “St. Petersburg State University of Telecommunications named after. prof. M.A. Bonch-Bruevich" "Arkhangelsk College of Telecommunications (branch) of the St. Petersburg State University of Telecommunications named after. prof. M.A. Bonch-Bruevich" Power supply of telecommunication systems Program, test task and guidelines for its implementation for correspondence students in the specialties: 70- Communications with moving objects; 709- Multichannel telecommunication systems; 7 -Radio communications, radio broadcasting and television; 73 -Communication networks and switching systems. Arkhangelsk 03

2 Power supply for telecommunication systems. Working programm. Test task for correspondence students. Compiled by: Popova O.M. ACT (branch) SPbSUT, Arkhangelsk. 03. Reviewed and recommended by the cycle commission of General professional disciplines of the Arkhangelsk College of Telecommunications (branch) of St. Petersburg State University of Technology named after. prof. M.A. Bonch Bruevich. Arkhangelsk College of Telecommunications (branch) of St. Petersburg State University of Telecommunications. prof. M.A. Bonch Bruevicha, 03. Condition. oven l. 0.44

3 Explanatory note The subject “Power supply of telecommunication systems” is a mandatory discipline in the cycle of general professional disciplines for specialties: 709 Multichannel telecommunication systems, 7 Radio communications, radio broadcasting and television, 73 Communication networks and switching systems, 70 Communications with moving objects. The purpose of studying this discipline is the theoretical and practical training of students in the field of power supply of telecommunication systems to such an extent that they can ensure competent operation of power supply devices, timely detect and eliminate faults, restore the operation of power supply equipment, evaluate the efficiency and energy intensity of power supply equipment. As a result of mastering the discipline, the student must know: sources of electrical energy to power various devices used in communications organizations, power supply and power supply systems of communications organizations. must be able to: control the operating modes of the power supply installation, read block diagrams, apply knowledge in practice, monitor the performance of uninterruptible power supplies. In order to study the educational material, it is envisaged to complete one home test and independent work of students according to the educational map. The numbers of textbooks indicated in the educational methodological map correspond to the numbers of textbooks in the list of references given at the end of the methodological instructions.

4 Educational and methodological map of the discipline “Power supply of telecommunication systems” Name of sections and topics Number of hours of review laboratories stand on their own. work Section. General information about power supply of communication devices Topic. Current state of power supply devices. Types of energy sources Topic. Three-phase system 0. Section. Autonomous power supplies Topic.. Batteries Topic. Direct energy converters Section 3 Electromagnetic power supply devices Topic 3. Electric reactors Educational literature index page Topic 3. Transformers Section 4. Rectification of alternating current Topic 4. Rectifier circuits Topic 4. Operation of a rectifier for various types of loads Topic 4.3 Controlled rectifiers 0. Section. Voltage converters

5 Topic. Anti-aliasing filters 0. Subject. Voltage converters Section 6. Voltage and current stabilizers Topic 6. Parametric voltage and current stabilizers Topic 6. Compensating DC voltage stabilizers Topic 6.3 Compensating stabilizers with pulse regulation Section 7. Rectifier devices Topic 7. Secondary power supplies Topic 7. Rectifier devices with transformerless input Section 8. Power supply system of a communication enterprise Topic 8. Power supply of communication enterprises Topic 8. Power factor correction Section 9. Power supply of equipment of communication enterprises

6 Topic 9. Power supply systems for communication equipment Topic 9. Uninterruptible DC power system Topic 9.3 Uninterruptible AC power system Section. Electrical installation of a communications enterprise Topic. Power supply of equipment (in specialty) Specialty 70 Power supply of equipment for communications with moving objects Specialty 709 Power supply of equipment of NUP and NRP Specialty 7 Power supply of equipment of radio communication and broadcasting systems Specialty 73 Power supply of automatic telephone exchange equipment Topic. Electrical installation equipment monitoring and control system Topic.3 Electrical supply safety. Grounding Topic.4 Calculation and selection of equipment for electrical installations of uninterruptible power supply Total for the discipline 8 36

7 WORK PROGRAM OF THE TRAINING DISCIPLINE “POWER SUPPLY OF TELECOMMUNICATION SYSTEMS” Section General information about the power supply of communication devices Topic. Current state of power supply devices. Types of energy sources Introduction. The essence, role and place of discipline in the process of preparation for professional activity. The purpose and objectives of the development of energy, electronics and communications technology. Prospects for the development of power supply. Primary energy sources, their application. Secondary energy sources, their application. Subject. Three-phase system Receiving three-phase current. Star connection of generator and consumer phases. Connection of the generator and consumer phases with a triangle. As a result of studying this section, the student should know: the main sources of power supply, the relationship between phase and linear values ​​of voltages and currents for various connection diagrams. Section Autonomous power supplies Topic. Batteries Lead-acid batteries, classification, design. Operation of a lead-acid battery. Electrical parameters of a lead-acid battery. Features of battery operation. Modern types of batteries. Laboratory work “Study of battery design” Topic. Direct energy converters Galvanic cells. Thermoelectric generators. Solar panels. Nuclear batteries. As a result of studying this section, the student should have an idea of: DC energy sources, the scope of application of these sources; know: battery design, basic

8 electrical characteristics of batteries, features of their operation; be able to: decipher the symbol of batteries. Section 3 Electromagnetic power supply devices Topic 3. Electric reactors Magnetic circuit. Magnetic materials. Chokes. Topic 3. Transformers The principle of operation of a transformer, classification of transformers. Transformer operating modes. Design of single-phase power transformers. Three-phase transformers. Laboratory work “Study of the operation of a single-phase transformer” As a result of studying Section 3, the student should have an idea of: the classification of transformers, the design and purpose of chokes and transformers; know: the principle of operation of a transformer, the design features of a three-phase transformer, the relationship between phase and linear values ​​of voltages and currents for various winding connection schemes. Section 4 Rectification of alternating current Topic 4. Rectifier circuits Classification of rectifiers. Basic parameters of rectifiers. Block diagram of the rectifier. Single-phase half-wave rectification circuit. Single-phase bridge rectification circuit. Three-phase rectification circuits, cascade rectification circuits. Laboratory work 3 “Study of single-phase rectification circuits” Practical work “Calculation of a rectifier” Topic 4. Operation of a rectifier for various types of loads Influence of the nature of the load on the operating mode of the rectifier. Features of rectifier operation for capacitive load. Features of the operation of a rectifier for an inductive load. Voltage multiplier circuit. Operation of rectification circuits on a battery.

9 Topic 4.3 Controlled rectifiers Block diagram of a controlled rectifier. Methods for controlling thyristors. Single-phase rectification circuit using thyristors. Three-phase bridge rectification circuit using thyristors. Laboratory work 4 “Research of the rectification circuit using thyristors” As a result of studying section 4, the student should know: the operation of single-phase and three-phase current rectification circuits; operating features of controlled rectifiers; have an idea: about the features of the rectifier operation for resistive and reactive loads; about the elements used in rectification circuits. Section Voltage converters Topic. Smoothing filters Rectified voltage ripple, its effect on the operation of communication equipment. Requirements for anti-aliasing filters. Anti-aliasing filter parameters. Inductive, capacitive filters. Anti-aliasing RC filters. L-shaped LC filter. Multi-stage LC anti-aliasing filter. Resonant filters. Active anti-aliasing filters. Laboratory work “Study of the properties of anti-aliasing filters” Topic. Voltage converters Classification of voltage converters. Block diagram of a voltage converter. Transistor voltage converters. Thyristor voltage converters. Laboratory work 6 “Research of DC voltage converters” As a result of studying this section, the student should have an idea of: voltage ripple, its effect on the operation of equipment, secondary power sources, the use of inverters and converters; know: design, conditions for effective operation of anti-aliasing filters; operation of DC converters.

10 Section 6 Voltage and current stabilizers Topic 6. Parametric voltage and current stabilizers Classification of stabilizers. Main parameters of stabilizers. Parametric constant voltage and current stabilizers. Topic 6. Compensating DC voltage stabilizers Block diagrams of compensating stabilizers with continuous regulation. Series voltage stabilizer. Compensating stabilizers in integral design. Topic 6.3 Compensating stabilizers with pulse regulation Classification of pulse stabilizers. Block diagram of a pulse stabilizer. Circuits of the power part of a pulse stabilizer. On-off switching DC voltage stabilizer. Voltage stabilizer with pulse-width current regulation. Laboratory work 7 “Study of a compensating constant voltage stabilizer” As a result of studying section 6, the student should have an idea of: destabilizing factors, elements used in stabilizers; know: features of stabilizers, main characteristics of stabilizers. Section 7 Rectifier devices Topic 7. Secondary power supplies General information about rectifier devices. Block diagram of rectifier devices of the VUT series. Block diagrams of secondary power supplies with output voltage stabilization. Laboratory work 8 “Study of the VUT rectifier device” Topic 7. Rectifier devices with transformerless input Purpose and technical characteristics of VBV-60. Block diagrams of VBV. Schematic diagram of the VBV rectifier. Operation of the power part of the circuit. Stabilization and regulation of output voltage.

11 Laboratory work 9 “Study of the rectifier device VBV” As a result of studying section 7, the student should have an idea of: the nomenclature of VUT, VBV, the features of the operation of rectifiers with a transformerless input; know: block diagram of the power part of rectifiers, design, methods of voltage stabilization, basics of technical operation. Section 8 Power supply system of a communications enterprise Topic 8. Power supply of communications enterprises Electrical installations of communications enterprises. Purpose. Compound. Classification of electrical receivers according to the conditions of reliability of power supply. Structural diagrams of energy supply to consumers of the first and second categories. Own power plants. Transformer substations. Laboratory work “Study of switching and distribution equipment of alternating current” Topic 8. Power factor correction Power factor. Capacitor installation. Passive power factor correctors. Power factor correction in VBB. As a result of studying Section 8, the student should have an idea of: the classification of consumer electrical installations according to power supply conditions, the purpose of power factor correction, and methods for increasing it; know: the purpose of the main elements of electrical installations; be able to: draw up an electrical installation diagram for a specific situation. Section 9 Power supply of equipment of communication enterprises Topic 9. Power supply systems of communication equipment Classification of power supply systems. Buffer power supply system. Ways to improve the quality of power supply of the buffer system. Battery-free power supply system.

12 Topic 9. Uninterruptible DC power system Purpose of the installation and operating principle of the UPS. Block diagram of a DC UPS. Direct current power supply devices (DC power supply devices) Laboratory work “Research of a direct current uninterruptible power supply device (DC power supply device)” Topic 9.3 AC uninterruptible power supply system Classification of uninterruptible power supplies. Double conversion uninterruptible power supply. Converter rectifier. Converter inverter. Disadvantages of UPS and ways to eliminate them. Laboratory work “Study of thyristor inverter IT-0/” Laboratory work 3 “Study of AC UPS” As a result of studying section 9, the student should have an idea of: about modern power supply installations; know: power supply systems for communication equipment, operating modes of power supply installations, composition and purpose of power supply installations and uninterruptible power supply installations. Section Electrical installation of a communications enterprise Topic. Power supply of equipment (by specialty) Specialty 70. Power supply of equipment for communications with moving objects. Features of power supply for equipment for communications with mobile objects. Power supply installation of base stations and switching center. Power supply for mobile phones. Specialty 709. Power supply of NUP and NRP equipment Electrical installation of a serviced amplification point. Organization of remote nutrition. Schemes and parameters of remote power supply circuits. Features of constructing an electrical power supply installation for NRP FOCL. Block diagram of the electrical installation on the NRP fiber optic line.

13 Specialty 7. Power supply of equipment for radio communication and broadcasting systems Electrical installation of RRL station. Electrical installation of a television center. Power supply of equipment of radio transmitting centers. Specialty 73. Power supply of automatic telephone exchange equipment Power supply of automatic telephone exchange equipment. Features of power supply of electronic telephone exchanges. Block diagram of the power supply of an electronic telephone exchange. Subject. Monitoring and control system for electrical installation equipment Power supply systems for communications enterprises. Basic provisions of the system. Structure of the control and management system. Information exchange infrastructure. Topic.3. Electrical supply safety. Grounding General safety requirements. Safety system functions dependent on power supply. Electrical safety. Fire safety. Information Security. Types of grounding systems. Electrical connection of grounded parts of equipment. Protection of equipment from surge currents and overvoltages. Source protective shutdown devices. Laboratory work 4 “Familiarization with the existing electrical installation of a communications enterprise (specialty)” Topic.4 Calculation and selection of equipment for electrical installations of uninterruptible power supply Initial calculation data. Calculation and selection of battery type. Calculation and selection of rectifiers. Calculation of DC current distribution network. As a result of studying Section 9, the student should have an understanding of: the electrical installations of base stations and the switching center (specialty 70), the electrical installations of radio communication and broadcasting enterprises (specialty 7), the electrical installations of electronic automatic telephone exchanges (specialty 73), the features of organizing remote power supply on fiber-optic lines ( specialty 709), general requirements and electrical safety measures; know: about the peculiarities of power supply of communication equipment with moving objects

14 (specialty 70), schemes for organizing remote power supply (specialty 709), features of the power supply of electronic automatic telephone exchanges (specialty 73), features of the power supply of radio communication enterprises (specialty 7), purpose and types of grounding systems; be able to: choose the type and number of rectifiers and batteries. General instructions for completing and completing tests. The version of the test task is selected in accordance with the individual code of the students. Before completing the assignment, you should study the relevant sections of the textbook. 3 Read the guidelines for completing this test task. 4 Test work should be done carefully in a separate notebook in a cage, observing the margins. It is acceptable to carry out the test using a computer in A4 format. When completing the work, the following rules must be observed: write down the complete conditions of the problem and the initial data for the calculation; calculations in problems must be accompanied by the necessary brief explanations; the formulas used for calculations must be presented in a general form, and the symbols included in the formula must be explained; the result of the calculation must be calculated to three significant figures, not counting the leading zeros; graphic representation and symbols of circuit elements must be made in accordance with the requirements of GOST; drawings should be numbered in the order they appear and accompanied by captions; at the end of the work, you should indicate a list of literature used, publisher, year of publication, the student’s personal signature and the date of completion of the work are required; The work is sent for review in accordance with the academic schedule.

15 Test task TASK Draw a circuit of the rectifier indicated for your option in the table and, using timing diagrams, explain the principle of its operation. Calculate the given rectifier according to the following points: Select the type of silicon diodes. Determine the effective values ​​of voltage and current in the secondary winding of the transformer. 3 Determine the transformation ratio of the power transformer. 4 Determine the coefficient of performance (COP) of the rectifier. Determine the pulsation coefficient Km. 6 Determine the ripple frequency f of the fundamental (first) harmonic. The calculation data is given in the table. Table Initial data Initial data Rectified voltage U 0, V Rectified current I 0, A 3 Rectification circuit Option number Single-phase bridge Single-phase full-wave with transformer midpoint output Three-phase half-wave (Mitkevich circuit), connection of transformer windings Three-phase bridge (Larionov circuit), connection transformer windings 4 Mains voltage U c, V Mains frequency f c, Hz Ripple coefficient of the first harmonic at the load (at the filter output) K OUT 0.00 0.00 0.003 0.009 0.004 0.00 0.00 0.003 0.00 0.00

16 Guidelines for solving the problem Before starting to solve the problem, you should study the textbook pages recommended in the text of the program. To select the type of silicon diodes, it is necessary to determine the reverse voltage on the diode U OBR and the average forward current through the diode I CP. The data for their calculation are given in the table. The type of silicon diode is selected according to the table. 3, based on calculations of the values ​​of U OBR and I SR, so that the permissible values ​​of the corresponding quantities for the selected type exceed the calculated ones, U OBR max >U OBR; I PR SR > I SR. The calculation of the effective values ​​of voltage U and current I in the secondary winding of the transformer is determined using the formulas in the table. 3 The transformation ratio of a power transformer is calculated by the formula: U ktr, () U where U is the effective value of the phase voltage in the primary winding of the transformer, taken equal to the network voltage U C, V; U is the effective value of the voltage in the secondary winding of the transformer, V (see paragraph). 4 Calculation of rectifier efficiency. The efficiency of the rectifier without taking into account the smoothing filter is determined by the formula: P0, () P R P 0 TP D where P 0= U 0 I 0 active power at the load, W; - power loss in the transformer, W; R TR R D - power loss in diodes, W. 4. Calculation of power losses in the transformer is determined by formula 3: Р Р, (3) ТР where Р ТР is the calculated power of the transformer, determined from the table data for a given rectifier circuit, W; - transformer efficiency, for calculations is taken equal to 0.8. TR TR

17 Table Parameters Reverse voltage on the diode Urev Average value of the forward current through the diode Isr 3 Rectifier phase m 4 Effective value of the voltage of the secondary winding of the transformer U Effective value of the current of the secondary winding of the transformer I 6 Effective value of the current of the primary winding of the transformer I 7 Rated power of the transformer RTR single-phase bridge single-phase full-wave with transformer midpoint output Rectification circuits three-phase half-wave (-) three-phase bridge (-) 7 Uо 3.4 Uо, Uо Uо 0, Io 0, Io 0.33 Io 0.33 Io 3 6, Uо, Uо 0.8 Uо 0.43 Uо Io 0.707 Io 0.8 Io 0.8 Io, Po, 34 Po, 34 Po Po

18 Table 3 Type of diodes U arr max Irev.sr Urev.sr Irev.sr Type of diodes U arr max Irev.sr Urev.sr Irev.sr D4 D4A D4B D YES DB D3 D3A D3B D3 D3A D3B D33 D33B D34B D4 D4A D4B D43 D43A D43B D4 D4A D4B D46 D46A D46B D47 D47B D48B KD0A KD0G D30 D303 D304 D30 D0A D0B D0V D0G KD0A KD0V KD0D KD0ZH KD0K, 3, 0.9 0.9 0, 0.3 0, 0.3 0.8 0, - 6 D-D-3 D-40 V V V0 DL- DL-6 DL- DL-3 DL-40 VL VL VL,,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, 3 0.7 0.7 0.7 0, 0, 0, 0, 0, 0.0 0.0 4.0 6.0 6.0.0,0.0.0 4.0 4.0 4 .0.0 8.9

19 4. Calculation of power losses in diodes depends on the rectification circuit: for a three-phase half-wave rectification circuit and a single-phase current rectification circuit with the output of the transformer midpoint, power losses in diodes are calculated according to formula 4, W: Рд = Upr.sr Io, (4) where Upp.cp - permissible forward voltage on the selected diode, V (see table 3). in bridge rectification circuits, current flows through two diodes connected in series, therefore power losses in the diodes are determined by the formula, W: Рд = Upr.av Io. () The ripple factor of the fundamental (first) harmonic at the rectifier output is calculated using formula 6: K P m. (6) 6 The ripple frequency of the fundamental (first) harmonic f, Hz is determined by formula 7: f = m fc, (7) where m is the number of rectified current pulses per period (see table); fc - network frequency, Hz. TASK Calculate the smoothing L-shaped LC filter connected after the rectifier using the following points: Determine the smoothing coefficient q. Determine the parameters of the smoothing filter elements. 3 Draw a diagram of the calculated L-shaped LC filter, taking into account the number of links in the filter. The data for the calculation are given in the table. Methodological instructions for solving the problem Calculation of the parameters of the elements of the smoothing LC filter included at the output of the rectifier (task) is carried out in the following order. Calculate the smoothing coefficient q using formula 8: K K q= P HIGH, (8)

20 where Kp is the ripple coefficient of the first harmonic at the filter input (at the rectifier output), determined for a given rectifier circuit according to formula 6; Kp.out - ripple coefficient of the first harmonic at the filter output (at the load), see table. Based on the calculated value of q, the number of LC filter sections is selected. If q<, то применяется однозвенный LC - фильтр, и в этом случае qзв= q, где qзв - коэффициент сглаживания одного звена LC - фильтра. Если q >, then a two-tier LC filter is used. Since the use of parts of the same type is more economical than different types, the same elements L and C are included in both links of the two-link filter. In this case, the smoothing coefficient of each link is determined by formula 9: qsq q. (9). Calculate the inductance and capacitance values ​​of the smoothing filter. One of the conditions for choosing the inductance of the filter choke is to ensure the inductive response of the filter to the rectifier. The minimum value of the inductor inductance that satisfies this condition is determined by the formula, H: L U0 (m) m I 3.34 f DRmin The value of the filter capacitance is calculated by the formula, μF: (qv) C m L DR min From Table 4, you should select the type of capacitor with rated capacity, based on the calculated value of capacitance C and the rated voltage of the capacitor U NOM, the value of which is determined by the formula: 0 C () () U nom >, U 0. () If in Table 4 there is no capacitor with the calculated capacitance for the required voltage , then you should select a capacitor with the maximum rated capacity for the calculated rated voltage and connect from two to five such capacitors in parallel with each other. In this case, it may turn out that the total capacitance of five parallel-connected capacitors C TOT is several times (...) less than the calculated value of the filter capacitance C. Obtaining the calculated value of the filter capacitance by further increasing the number of capacitors is impractical, therefore the total capacitance C TOT of the selected capacitors is considered nominal filter capacity.

21 In this case, the value of inductance L DR min should be increased by the same number of times as C TOT is less than the calculated filter capacitance C, since it is necessary to meet the condition LC = const..3 Draw a smoothing filter circuit taking into account the number of links and the number of parallel-connected capacitors in each filter link that resulted from your calculation. Table 4 - Capacitors with oxide dielectric Type Rated voltage, V K 0-6, K 0-8 6, K K 0-3A K K, Nominal capacitance, μF; ; 47; 0; 0; 470; 00; 00; 000 ; ; ; 47; 0; 0; 470; 00; 000 ; 47; ; ; 47; 0; 0; 470; 00; 00; 000 ;,; 4.7; ; 47; 0; 00 ;,; 4.7; ; 0 ;,; 4.7; ; ; 47; 0; ; ; ; ; ; ; 000; 000; ; 000; ; 4700; ; ; 00 ; ; 47; 0; 0; 470; ; 47; 0; 0; 470 4.7; ; ; 47; 0; 0,; 4.7; ; ; 47; 0; 0 000; 000; ; ; 000; ; 00; 00; 3300; ; 40; 0; 330; 470; 680; 00; 000; 00 47; 68; 0; 0; 0; 330; 470; 680; 00 47; 68; 0; 0; 0; 330; ; 0; 0; 470; 00; 00; 4700; ; 0; 0; 470; 00; 00; 4700; 000 ; 47; 0; 0; 470; 00; 00 ; 47; 0; 0; 470; 00; 00 ; 47; 0; 0; 470; 00; 00 4.7; ; ; 47; 0; 0 ; ; 4.7; ; ; 47; 0

22 TASK 3 Calculate the power supply installation EPU-60 (EPU-48) according to the following points: Select the type and number of batteries in the battery required for emergency power supply to the load. Decipher the designation of the selected batteries. Select the type of power supply installation of the communications enterprise (UEPS) and the number of rectifier devices of the VBV type. 3 Calculate the energy parameters of the rectifier-battery installation. The calculation data is given in the table. Table Initial data Load current I n, A Rated voltage U nom, V Power supply category First consumer Electrolyte temperature, t o 4 0 Option number Special group First Special group Ik First Special group Ik First Special group Ik First Special group Ik Guidelines for solving the problem 3 Calculation and selection of battery. Calculation of battery capacity The battery provides power to the load in emergency mode. The required capacity of a lead-acid battery OP Z S (with liquid electrolyte), reduced to normal discharge conditions, is determined by formula 3, Ah: Iheattp Qt, (3) [ 0.008(t 0)]

23 where Q t is the calculated battery capacity in ampere-hours, normalized to the normal temperature of the electrolyte (0 0 C), A h; I NAGR load current specified in the source data, A; t p battery discharge time in hours, depends on the category of power supply: for consumers of a special group of the first category - hours, for consumers of the first category - 8 hours, hours; - capacity selection coefficient, depending on the discharge time, t p; at t p =h q =0.94 at t p =8h q =0.64 t o is the actual temperature of the electrolyte indicated in the initial data. Selecting the battery type. Since the battery consists of two parallel groups, the resulting capacity must be divided by two. The choice of battery type is made according to Table 6. For example, we divide the calculated battery capacity Q t = 800Ah by two and select a battery of type 6 OP Z S 40 with a rated capacity Q nom = 40Ah. Select a battery whose rated capacity must exceed the calculated one. In the selected type of battery, the first number of the code corresponds to the number of positive plates, the letter designation stands for “stationary maintenance-free batteries with tubular positive plates”, the last number shows the rated capacity Q NOM of the battery at -hourly discharge with rated current..3 Number of elements in one group of the battery determined by formula 4: U NOM n= (4) where U nom =60 (48) - rated voltage at the load, V; rated voltage of one battery, V.

24 Table 6 Element type 3 OR Z S 0 Capacity, Ah Discharge current, A hours hours 3 0, 3 0, OR Z S 00 OR Z S 0 6 OR Z S 300 OR Z S 30 6 OR Z S 40 7 OR Z S OR Z S OR Z S 800 OR Z S 00 OR Z S 00 OR Z S 00 OR Z S 87 6 OR Z S OR Z S 00 4 OR Z S Calculation and selection of power supply installation for a communications enterprise (UEPS). Calculation of load current UEPS. The rectifier installation must provide power to the load and charge the battery after it is discharged during shutdown

25 electricity. Therefore, the total EPU current (I EPU) must be the sum of the load current (I LOAD) and the battery charge current (I CHARGE). The charge current of two groups of batteries is calculated by the formula, A I CHAR = 0. Q nom () where Q nom is the nominal capacity of the selected battery, Ah. The load current of the rectifier installation is determined by the formula6, A I EPU = I LOAD + I CHAR (6) . From Table 7, you should select a device of the UEPS-3 or UEPS-3K type at Unom = 60V or 48V and the value of I EPU with VBV rectifiers (rectifier devices with a transformerless input). For example, with a design current I EPU = 0A, U NOM = 60V, we select UEPS-3 60/ M. In the selected type UEPS-3: the number 60 means the rated voltage, V; number 0 - maximum output current when fully equipped with rectifiers, A; numbers 06 - maximum number of rectifiers installed in the device; numbers 06 - number of rectifiers installed in the device; index M - modernized. Table 7 Device type UEPS-3 60/ M Rectifiers VBV Type Quantity, pcs. VBV 60/ -3K 6 UEPS-3 60/300--M UEPS-3K 60/80-44 UEPS-3 48/ M UEPS-3 48/360--M UEPS-3K 48/0-44 VBV 60/ - 3K VBV 60/0-3K VBV 48/30-3K VBV 48/30-3K VBV48/ -3K The number of rectifiers (modules) required to complete the UEPS is selected from condition 7: I EPU VU (7) IVBV

26 where k vu is the number of parallel-connected rectifier modules; I VBV maximum current of one rectifier, A To the selected working set of VBV, one reserve one of the same type should be added. The types and main electrical characteristics of rectifiers are shown in Table 8. Table 8 Type of rectifier VBV-60/3K VBV-60/0 3K VBV-60/30 K VBV-48/30-3K VBV-48/-3K Main electrical characteristics Range Maximum Adjustment range of output output voltage, power, current, A V W Efficiency,9 0.9 0.99 40.9 0.9 Power factor 0.99 0.98 Note: symbol of the type of rectifier given in the table 4, deciphered as follows: VBV - rectifier devices with transformerless input; the number in the numerator is the rated output voltage, V; the number in the denominator is the maximum load current, A; number 3 (or) performance number; the letter K means the presence of a power factor corrector. 3 Calculation of energy parameters of a rectifier-battery installation. 3. The maximum power consumption of UEPS-3 from the alternating current network, taking into account the efficiency of the rectifier device, is calculated by formula 8, kW: where VBV EPU NOM R max = VBV - efficiency of the rectifier device. I U (8)

27 3. The total power consumed by the installation from the alternating current network is calculated according to the formula 9, kW: P MAX P S = cos, (9) where cosφ is the power factor of the selected type of VBB. TASK 4 Draw an electrical functional diagram of the EPU-60 (48) based on the data obtained in task 3. Indicate the composition and purpose of the main equipment of the EPU. 3 Consider the load power circuit according to the ECU diagram. Explain how uninterruptible power supply of communication equipment is carried out from the electronic control unit: 3. in the presence of an alternating current network (normal mode), (for options from to 4); 3. when the AC power supply is lost (emergency mode), (for options from to 7); 3.3 when restoring the AC network (post-emergency mode), purpose (for options from 8 to); Guidelines for completing task 4 A typical diagram of the EPU-60 is shown in the figure. The diagram should show the number of rectifier modules (RMMs) that resulted from your calculation. The typical EPU-48 circuit is constructed in a similar way. The figure shows a block diagram of the EPU-60, called a buffer modular power supply system. A feature of such systems is the parallel connection of the battery to the output of the rectifiers and the powered load. The EPU-60 (48) includes: a set of rectifier devices of the VBV type, consisting of K modules for power supply of communication equipment, charging and recharging the battery; automatic switches A-A-K for connecting rectifiers to the AC input switchboard; automatic switches A-A-K for connecting the output of the rectifiers to the battery and load; two-group battery AB IAB; deep discharge automatic (contactor) AGR to disconnect the battery from the equipment during deep discharge; battery circuit breakers AB, AB for connecting the battery to the load;

28 current shunts for measuring current in the battery circuit Ш and in the load circuit Ш; automatic switches An-An-m for connecting the load; controller for monitoring the condition of rectifiers, circuit breakers, fuses; to monitor the voltage and current of the battery and load; turning it off during deep discharge; ambient temperature; the capacity of the battery, the presence of all three phases of the power supply. When any of the machines is turned off or the protection is triggered, the corresponding information appears on the controller display. Figure - Electrical functional diagram of EPU-60 Operation of EPU In normal mode, power supply to communication equipment and continuous recharging of the battery is carried out from working VBV. Circuit breakers A-A-K and A-A-K are closed. In emergency mode, the equipment is powered from a discharging battery. In order to prevent sulfation of batteries as a result of their unacceptable deep discharge,

29, an AGR contactor is introduced into the power supply system, disconnecting the battery from the equipment. When power supply is restored, rectifiers provide power to the equipment and charge the battery without disconnecting it from the load. Advantages of a buffer modular power supply system: high quality of generated energy, as the smoothing stabilizing properties of a battery connected in parallel to the load are used; a minimum number of devices included in the EPU, which ensures low cost and high reliability; high efficiency, almost equal to the efficiency of VBB; high power factor (in case of using rectifiers with power factor correction). List of sources used: Power supply for devices and telecommunication systems; Textbook for universities / V.M. Bushuev, V.A. Deminsky, L.F. Zakharov and others - Moscow: Hotline-telecom, 009. Shchedrin, N.N. Energy supply of telecommunication systems: Textbook for open source software. Textbook for open source software. Moscow: UMC Federal Communications Agency, 0. Additional sources: Sizykh, G. N. Power supply of communication devices [Text]: textbook for technical schools / G. N. Sizykh. - Moscow: Radio and communications, p. Hilenko, V. I. Power supply of communication devices [Text]: textbook / V. I. Hilenko, A. V. Hilenko. - Moscow: Radio and communications, p. 3 Materials from the website of the Ferropribor plant. 4 Materials from the website of NPP GAMMAMET.”

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Introduction

Trunking radio communication systems, which are radial-area mobile VHF radio communication systems that automatically distribute repeater communication channels between subscribers, are a class of mobile communication systems focused primarily on the creation of various departmental and corporate communication networks, which provide for the active use of subscriber communication modes in group. They are widely used by security and law enforcement agencies, public security services, transport and energy companies in various countries to ensure communication of mobile subscribers with each other, with landline subscribers and subscribers of the telephone network.

There are a large number of different standards for trunked public mobile radio communication systems, differing from each other in the method of transmitting voice information (analog and digital), the type of multiple access, time or code, the method of searching and assigning a channel (with decentralized and centralized control), the type of control channel (dedicated and distributed) and other characteristics.

We live in a time when access to information is the most important factor in ensuring the efficiency and effectiveness of organizations. Therefore, it is necessary to ensure that the level of mobile access to information matches the growing level of mobility of modern organizations. This also applies to Internet access and the use of Internet-based solutions.

Since the beginning of the 90s. SmartZone systems are installed all over the world. Scotland Yard and Yukos, the municipality of Rome and the Russian Ministry of Internal Affairs, transport enterprises and commercial operators appreciated the capabilities of the system, which can provide communication across the borders of not only cities or regions, but also countries. Each of the numerous users finds in the system advantages that are attractive to him in the first place. Speech encryption and data transmission, uninterrupted telephone conversation and telemetry, subscriber fleet dispatching and much more have forced more than a million people to choose systems from the SmartNet family, to which SmartZone belongs.

Modern digital trunking radio communication systems mark a new stage in the development of mobile radio communications in Russia and throughout the world. Compared to cellular mobile radio communication systems, trunking systems turn out to be more economical in some cases, differing in the variety of implementations within the same standard when using equipment from different manufacturers.

The main objective of this course work is to consider the prospects for the development of trunking communications (various standards) in the world and in Russia as a whole.

1. Trunkingradioconnection. Basic Concepts

Trunking radio communication systems, which are radial-area mobile VHF radio communication systems that automatically distribute repeater communication channels between subscribers, are a class of mobile communication systems focused primarily on the creation of various departmental and corporate communication networks, which provide for the active use of the mode connections of subscribers in the group. They are widely used by security and law enforcement agencies, public security services of various countries to ensure communication between mobile subscribers among themselves, with landline subscribers and subscribers of the telephone network.

Digital standards for trunked radio communications have not yet become widespread in Russia, but we can already talk about their active and successful implementation.

Digital trunking communication is characterized by such characteristics as (has advantages such as)

1. High efficiency of communication.

2. Data transfer.

3. Communication security.

4. Communication services.

5. Possibility of interaction. For public security services, the requirement to ensure the possibility of interaction between departments of various departments to coordinate joint actions in emergency situations: natural disasters, terrorist attacks, etc. is especially relevant.

The most popular digital trunking radio communication standards that have earned international recognition, on the basis of which communication systems have been deployed in many countries, include:

EDACS, developed by Ericsson;

TETRA, developed by the European Telecommunications Standards Institute;

APCO 25, developed by the Association of Public Safety Communications Officials;

Tetrapol, developed by Matra Communication (France);

iDEN, developed by Motorola (USA).

All these standards meet modern requirements for trunked radio communication systems. They allow you to create various configurations of communication networks: from the simplest local single-zone systems to complex multi-zone systems at the regional or national level.

1.1 General information about digital trunked radio standards

EDACS system

One of the first digital trunking radio communication standards was the EDACS (Enhanced Digital Access Communication System) standard, developed by Ericsson (Sweden).

Digital EDACS systems were produced in the frequency ranges 138-174 MHz, 403-423, 450-470 MHz and 806-870 MHz with a frequency spacing of 30; 25; and 12.5 kHz.

The information transmission speed in the working channel corresponds to 9600 bit/s.

Speech coding in the system is carried out by compressing a pulse-code sequence at a speed of 64 Kbit/s, obtained using analog-to-digital signal conversion with a clock frequency of 8 kHz and a bit width of 8 bits. The main functions of the EDACS standard, providing the specifics of public safety services, are various call modes (group, individual, emergency, status), dynamic call priority control (up to 8 priority levels can be used in the system), dynamic modification of subscriber groups (regrouping), remote shutdown radio stations (in case of loss or theft of radio equipment).

One of the main objectives of the system development was to achieve high reliability and fault tolerance of communication networks based on this standard.

Today, a large number of EDACS standard networks have been deployed around the world, including multi-zone communication networks used by public security services in various countries. There are about ten networks of this standard operating in Russia. At the same time, Ericsson is not working to improve the EDACS system, has stopped supplying equipment for the deployment of new networks of this standard and only supports the functioning of existing networks.

TETRA system

TETRA is a digital trunked radio standard consisting of a number of specifications developed by the European Telecommunications Standards Institute (ETSI). The TETRA standard was created as a single pan-European digital standard. TETRA currently stands for Terrestrial Trunked Radio.

TETRA is an open standard, meaning that equipment from different manufacturers is expected to be compatible.

The TETRA standard includes specifications for the wireless interface, interfaces between the TETRA network and the integrated services digital network (ISDN), public switched telephone network, data network, private branch exchanges, etc.

The TETRA radio interface assumes operation in a standard frequency grid with a step of 25 kHz. The required minimum duplex spacing of radio channels is 10 MHz. For TETRA systems, some frequency subbands can be used. In European countries, security services are assigned the ranges 380-385/390-395 MHz, and for commercial organizations the ranges 410-430/450-470 MHz are provided. In Asia, TETRA systems use the range 806-870 MHz.

The TETRA standard provides two levels of security for transmitted information:

standard level, which uses radio interface encryption (providing a level of information security similar to the GSM cellular communication system);

high level, using end-to-end encryption (from source to recipient).

TETRA networks are deployed in Europe, North and South America, China, Southeast Asia, Australia, and Africa.

APCO 25 system

The APCO 25 standard was developed by the Association of Public Safety Communications Officials-international, which unites users of public safety communications systems.

The APCO 25 standard provides the ability to operate in any of the standard frequency ranges used by mobile radio systems: 138-174, 406-512 or 746-869 MHz.

The subscriber identification system incorporated in the APCO 25 standard allows you to address at least 2 million radio stations and up to 65 thousand groups in one network. In this case, the delay when establishing a communication channel in the subsystem in accordance with the functional and technical requirements for the APCO 25 standard should not exceed 500 ms (in direct communication mode - 250 ms, when communicating through a repeater - 350 ms).

Specialists from the Russian Ministry of Internal Affairs show the greatest interest in this standard. A pilot network (not yet trunking, but conventional radio communication) based on two base stations was deployed by the Russian Ministry of Internal Affairs in Moscow in 2001. In 2003, in St. Petersburg, for the 300th anniversary of the city, a dispatch radio network for 300 subscribers was deployed in the interests of various security forces.

Tetrapol system

Work on creating the Tetrapol digital trunking radio communication standard began in 1987, when Matra Communications entered into a contract with the French gendarmerie to develop and commission the Rubis digital radio communication network. The communication network was put into operation in 1994. According to Matra, today the French gendarmerie network covers more than half of the territory of France and serves more than 15 thousand subscribers.

Tetrapol standard communication systems have the ability to operate in the frequency range from 70 to 520 MHz, which, in accordance with the standard, is defined as a combination of two sub-bands: below 150 MHz (VHF) and above 150 MHz (UHF). Most of the radio interfaces for systems in these subbands are common; the difference lies in the use of different methods of noise-resistant coding and code interleaving.

The information transmission speed in the communication channel is 8000 bit/s.

Due to the fact that from the very beginning the Tetrapol standard was focused on meeting the requirements of law enforcement agencies, it provides various mechanisms for ensuring communication security aimed at preventing threats such as unauthorized access to the system, eavesdropping on ongoing conversations, creating intentional interference, traffic analysis specific subscribers, etc.

In 1997, Matra Communications won a tender to create a digital radio communications system for the Royal Thai Police. The contract is part of an order to modernize the police radio network, which will connect 70 police stations. It is expected to use the most modern system capabilities, including access to a centralized database, e-mail, end-to-end encryption of information, location determination. There are also reports of several systems being deployed in two other Southeast Asian countries, as well as for Mexico City police.

iDEN system

iDEN (integrated Digital Enhanced Network) technology was developed by Motorola in the early 90s. The first commercial system based on this technology was deployed in the United States by NEXTEL in 1994.

In terms of standard status, iDEN can be characterized as an enterprise standard with an open architecture. This means that Motorola, while retaining all rights to modify the system protocol, also licenses the production of system components to various manufacturers.

This standard was developed to implement integrated systems that provide all types of mobile radio communications: dispatch communications, mobile telephone communications, transmission of text messages and data packets. iDEN technology is aimed at creating corporate networks of large organizations or commercial systems that provide services to both organizations and individuals.

The iDEN system is based on MDVR technology. Each 25 kHz frequency channel carries 6 speech channels. This is achieved by dividing a 90 ms frame into 15 ms time intervals, each of which transmits information on its own channel.

The standard uses the standard frequency range for America and Asia 805-821/855-866 MHz. IDEN has the highest spectral efficiency among the considered digital trunking communication standards; it allows up to 240 information channels to be placed in 1 MHz. At the same time, the size of the coverage areas of base stations (cells) in iDEN systems is smaller than in systems of other standards, which is explained by the low power of subscriber terminals (0.6 W for portable stations and 3 W for mobile ones).

The first commercial system, deployed in 1994 by NEXTEL, is now nationwide with approximately 5,500 sites and 2.7 million subscribers. There is another network in the US, operated by Southern Co. iDEN networks are also deployed in Canada, Brazil, Mexico, Colombia, Argentina, Japan, Singapore, China, Israel and other countries. The total number of iDEN subscribers in the world today exceeds 3 million people.

iDEN systems have not been deployed in Russia and there is no information about the development of network projects of this standard.

1.2 Operators of multi-zone trunking networks

AMT. This is one of the first commercial radiotelephone operators in Russia. The AMT network of the MPT-1327 standard is built on the basis of Nokia equipment. Its coverage area includes the territory of Moscow and the Moscow region at a distance of up to 50 km from the Moscow Ring Road, as well as the Moscow region cities of Solnechnogorsk, Dubna and their environs. The company's services are designed for both individual consumers (radio telephones) and corporate customers (virtual departmental radio communication networks). The system uses full-duplex and half-duplex radios. In addition to voice communication, data transmission is supported. There is full access to the public telephone network and roaming with regions is provided.

ASVT (Rusaltai). The Rusaltai network is built on the basis of Actionet equipment from Nokia. The leading base station is located on the Ostankino tower, and 10 others are deployed in the Moscow region to ensure its full coverage and partial coverage of surrounding areas. For now, the network's services are positioned as radiotelephone services, that is, the client receives a radiotelephone with a direct Moscow number. However, unlike a cell phone, the subscriber device provided by the company is also capable of operating in half-duplex mode, which is used in trunking for group communication. The Rusaltai network uses not per-minute (as in cellular communications), but per-second billing, which, with a similar cost of airtime, allows subscribers to significantly reduce costs.

"RadioTel". This largest trunking operator in the North-West, and in Russia, is part of the Telecominvest group. The RadioTel company is the only St. Petersburg mobile communications operator that provides the construction of hierarchical communication systems for corporate users, trunking communications with the ability to access the GTS, emergency communications with Ambulance (03), duty services of the city administration and the Office of Civil Defense and emergency situations. The coverage area of ​​the RadioTel network includes the whole of St. Petersburg and the nearest suburbs. Terminal equipment is manufactured and supplied by Ericsson and Maxon corporations. At the beginning of 1996, the company created its own dispatch service, St. Petersburg Taxi 068, which currently serves more than 50% of taxi calls in the city by telephone.

In 1999, at the request of one of the St. Petersburg fuel companies, RadioTel developed the project “Data transfer for accepting payments using plastic cards of major payment systems.” The created system is multifunctional and allows solving several problems, including the task of ensuring transaction security.

In 1999, RadioTel won the tender to organize trunking communications for the Emergency Medical Service and supplied it with 350 pieces of equipment. Today, every ambulance in St. Petersburg is radio-equipped by this company.

"MTK-Trunk". The MTK-Trunk network is built on the basis of SmartZone equipment from Motorola. Six sites provide reliable communication in the capital and at a distance of at least 10 km from the Moscow Ring Road for portable radios and at least 50 km from the Moscow Ring Road for car radios. The network is aimed at collective users (organizations), which are characterized by high personnel mobility and random distribution of employees throughout Moscow and the region. Each client is allocated its own virtual network. Group and personal calls are made throughout the entire radio coverage area from any subscriber radio station without additional manipulations or switching. It is possible to establish communication outside the network coverage area in talk-around mode (direct channel), as well as exit from the subscriber station to the public telephone network.

"RadioLeasing" This is the first operator of a commercial trunking network in Moscow. Several networks are united under the Translink brand:

local networks in the 160 MHz range (on “direct” simplex channels);

pseudo-trunking network SmarTrunk II (since 1992);

multi-zone trunking network MRT-1327, built on the basis of Fylde Microsystems equipment.

Currently, five base stations (22 channels) are operating, which support reliable communication within 50 km from the Moscow Ring Road.

"Regiontrunk". The company provides radiotelephone communication services in Moscow and the Moscow region, as well as in the regions of Central Russia. The first communication network based on the ESAS protocol, operating in the 800 MHz band, was put into operation in 1997. Currently, six base stations are located in Moscow, which ensures reliable reception within the city for portable subscriber stations and in the near Moscow region for car devices. A distinctive feature of Regiontrank’s services is the development of professional business solutions that take into account the special requirements of customers. For example, a software and hardware complex “Taxi Dispatch Service” was created for a large Moscow taxi fleet.

"Center-Telko". The city integrated radiotelephone communication system "Sistema Trunk" was deployed in accordance with the decree of the Moscow government of October 29, 1996. The network is built on the basis of EDACS equipment, which ensures high security of communication channels and reliable operation of the system in any extreme situations. Four base stations support the operation of portable stations in Moscow and the immediate Moscow region (4-7 km from the MKAD), and automobile ones within 50 km from the MKAD. In addition to traditional services for radio communication networks, the System Trunk network provides services for transmitting digital data and determining the location of objects.

2. Prospectsdevelopment of trunking radio communications

A brief comparative analysis of these digital trunking radio communication standards according to the main criteria considered allows us to draw certain conclusions about the prospects for their development, both in the world and in Russia.

The EDACS standard has virtually no prospects for development. Compared to other standards, it has lower spectral efficiency and less functionality. Ericsson has no plans to expand the capabilities of the standard and has practically curtailed equipment production.

The iDEN standard does not provide many special requirements, and, despite its high spectral efficiency, is limited by the need to use the 800 MHz band. It is likely that systems of this standard have some potential and will continue to be deployed and operated, particularly in the Americas. In other regions, the prospects for deploying systems of this standard look dubious.

The Tetrapol standard has good technical performance and sufficient functionality, but, like the EDACS and iDEN standards, it does not have the status of an open standard, which can significantly hinder its development in technical terms, as well as in terms of the cost of subscriber and fixed equipment.

The TETRA and APCO 25 standards have high technical characteristics and broad functionality, including meeting the special requirements of law enforcement agencies, and have sufficient spectral efficiency. The most important argument in favor of these systems is the availability of open standards status.

At the same time, most experts are inclined to believe that the digital trunking radio market will be conquered by the TETRA standard. This standard enjoys wide support from most of the world's major equipment manufacturers and communications administrations in various countries. Recent events in the domestic professional radio communications market allow us to conclude that in Russia this standard will become more widespread.

Currently, the development of the second stage of the standard (TETRA Release 2 (R2)), aimed at integration with 3rd generation mobile networks, a radical increase in data transfer speed, the transition from specialized SIM cards to universal ones, further increasing the efficiency of communication networks and expanding possible service areas.

2.1 Overview of trunked radio projects in Europe

Many European countries have opted for digital trunking standards for professional radio networks. This article provides a brief overview of completed and ongoing projects in Europe.

The UK has already begun to implement and apply projects based on TETRA technology. The Public Safety Radio Communication Project team has created a TETRA network for the UK police force. Although the network was originally created for police use, project leaders hope that fire brigades and ambulance crews will soon join the ranks of users. The network is supported by a specially created operator company Airwave.

Finland began working on a national TETRA network in 1998. The first phase of the project was launched in January 2001, and the network now operates almost throughout Finland. The VIRVE network is currently used by a variety of users including police, fire, ambulance, border services, coast guards and the armed forces.

The C2000 project is being implemented in the Netherlands. The network is intended mainly for police, firefighters, ambulance services and other public services. Full completion of construction is expected in 2004. The total number of base stations will be about 400. The expected number of network users is 80 thousand.

Belgium supports a project called ASTRID (All-round Semi-cellular Trunking Radiocommunication system with Integrated Dispatchings). Like C2000 in the Netherlands, this project aims to create a national TETRA network. The planned network is primarily intended for use by local and federal police, firefighters, state security services, 100 (Ministry of Health) and general users. The implementation of the network began in 1998. The initial goal was to achieve national radio coverage by the end of 2003, but the design of the network was delayed. The main reason is said to be difficulties in obtaining permits for the installation of masts and antenna devices.

Given Germany's federal structure and the division of responsibilities at national and regional levels, the decision-making process to create a national network was complex and lengthy. In 1996, the authorities of various regions decided that it would be a digital network based on the European standard. They did not, however, specify which standard should be used. Shortly after this decision, the first pilot project based on the TETRA standard was created in Berlin. Subsequent reports recommended that a tender procedure for the national network be set up based on the same standard. Also, a TETRA network was created in the Aachen region. This network is part of the so-called Three Countries Trial. This project evaluates the effectiveness of the TETRA network when used by multiple countries. Countries included in this project: Belgium, Germany and the Netherlands. The TETRA networks of these countries were interconnected for testing.

Austria, Italy, Scandinavian countries, Ireland (not all are listed) have also begun implementing projects for professional radio communication networks based on TETRA. An advisory body consisting of representatives from 13 countries was organized to exchange experiences, develop a joint position and influence manufacturers, resolve common issues and provide mutual assistance. Representatives of the advisory body announced the frequency of meetings twice a year. The chairman of the body is a representative of the Netherlands.

However, not all European countries have opted for the TETRA standard. For example, the TETRAPOL standard, developed by the French company MatraCommunications, was chosen for implementation by the French police.

Also, a number of small TETRA local networks have been implemented in Spain, the Czech Republic and Switzerland.

2.2 Review of prospects for the development of trunking radio communications in Russia

The leading company in the trunking radio communications market in Russia is OJSC Tetrasvyaz, founded in 2004. Tetrasvyaz provides a full range of services for the creation of TETRA professional digital radio networks from design to commissioning, including the provision of services based on existing networks.

Tetrasvyaz is a leading Russian system and network integrator, a federal operator of services based on GLONASS/TETRA systems in terms of geography and number of subscribers, with extensive experience and broad capabilities in implementing large-scale telecommunications projects and its own solutions for various market segments. In 2007, it joined the ATGroup consortium. The professional presence area covers 40 regions and more than 70 cities of the Russian Federation. The head office is located in Moscow, regional offices are in St. Petersburg, Krasnodar, Nizhny Novgorod.

On April 7-8, the International Conference “Problems of modernizing the telecommunications infrastructure of Russia and the introduction of promising radio technologies”, organized by the Ministry of Communications and Mass Media of the Russian Federation, took place in Moscow. The main topic brought up for discussion during the conference was an assessment of the current state of radio communications as the most important element of Russia's infrastructure, prospects and directions for its further development.

At the conference, presentations were made by representatives of the Ministry of Telecom and Mass Communications, territorial departments of Roskomnadzor, research and design institutes, radio frequency service organizations, leading companies in the telecommunications industry, such as Svyazinvest, MTS, VimpelCom, Motorola. The audience was greatly interested in the report on the current state and prospects for the development of digital trunking radio communications in Russia, presented by the federal operator of professional radio communications services, Tetrasvyaz. The report discussed the European TETRA standard, which has a number of technological and functional advantages compared to public networks and the American APCO 25 trunking communication standard. Based on the standard, complex security and management systems are being developed both in megacities and in Russian regions. With the active participation and external control of government organizations, TETRA networks are being built in the Moscow, Vladimir, Kursk regions, in Sochi - for the 2014 Olympics, in Vladivostok - for the APEC 2012 summit to ensure effective interaction between law enforcement services

As noted in the report, the implementation of the concept of development of the TETRA standard in Russia until 2015 is associated with a number of key factors. Firstly, symbiosis with the Russian GLONASS system opens up new prospects for the use of TETRA as a reliable transport medium in satellite monitoring, control and dispatch systems for emergency services and law enforcement agencies. Secondly, ensuring a smooth transition of networks to the new generation TETRA-2 standard as the release appears on the market. Thirdly, the gradual creation of a unified TETRA space in Russia, forming a zone of safe life on a national scale.

The state is increasingly paying attention to promising investment projects in the field of telecommunications, many of which are associated with such large-scale image events as, for example, the first Russian Winter Olympics and the international summit of the countries of the Asia-Pacific region.

Conclusion

Almost all trunked mobile radio communication standards that exist today throughout the world are represented on the country's market. Russia is a country of telecommunications contrasts, and they must be eliminated if we are going to take a strong position in the global market of high telecommunication technologies. But, despite all the shortcomings, the domestic high-tech industry demonstrates a good 25 percent annual growth rate. Investing money in communications is a promising investment in business.

The development of trunking radio communications, undeservedly (and not without the help of cellular radio operators), has not received adequate growth in the Russian Federation in the past decade. Many managers, not correctly understanding the difference, compare professional trunking radio communications with cellular, and when it comes to the cost of subscriber equipment (which is two to three times higher than the cost of subscriber equipment for mobile radio communications), cellular radio communications ultimately wins. It remains unnoticed that mobile trunking radio communication is, first of all, operational radio communication, where subscribers are connected by simply pressing one or several keys.

There are many other advantages of trunked radio communications over cellular ones: data transfer, communication security, the ability to conduct conference radio communications, there is no worry about traffic, since often the fee (if it is a dedicated, commercial network) is only for the subscriber, without taking into account traffic.

The current version of the Federal Law of the Russian Federation “On Communications” provides for the creation of “dual-use” communication systems. However, this edition is silent about the creation of interdepartmental radio communication systems.

The state that owns the frequency range should influence the development and modernization of trunked communication networks, up to the creation of federal trunked mobile radio networks, and act as a referee in the creation of interdepartmental systems of trunked mobile radio communications.

WITHlist of used sources

1. Shloma A.M., Bakulin M.G. “New algorithms for generating and processing signals in mobile communication systems” [Text] Hot Line - Telecom, 2008 - 344 p.

2. Annabelle Z.D. “The world of telecommunications. Review of technologies and industry" [Text] Olympus-Business, 2002 - 400 p.

3. Dovgy S.S. “Modern telecommunications. Technologies and Economics" [Text] Eco-Trends, 2003 - 320 p.

4. Shakhgildyan V.V. “Radio transmitting devices: a textbook for universities” [Text] Radio and communications, 2003 - 560 p.

5. Katunin, G.V. Mamchev, V. N. “Telecommunication systems and networks. Volume 2. Radio communications, radio broadcasting, television. Training manual" [Text] Hotline - Telecom, 2004 - 672 p.

6. Popov O.B., Richter S.G. “Digital signal processing in audio broadcasting paths” [Text] Hotline - Telecom, 2007 - 341 p.

7. Mamchev G.V. “Fundamentals of radio communications and television. Textbook for universities" [Text] Hotline-Telecom, 2007 - 416 p.

8. Mamaeva N.S. “Digital television and radio broadcasting systems” [Text] Hotline - Telecom, 2007 - 254 p.

9. Galkin V.A., Grigoriev Yu.A. “Textbook for universities, on special. "Informatics and computer technology" [Text] "Bauman MSTU" - 608 p.

10. Krukhmalev V.V., Gordienko V.N. “Fundamentals of building telecommunication systems and networks” [Text] M: BHV, 2005. - 325 s.

Annex 1

trunking radio operator tetra

General information about EDACS, TETRA, APCO 25, Tetrapol, iDEN standards systems and their technical characteristics

	Characteristics of the communication standard (system)
	Standard developer	Ericsson (Sweden)			Matra Communications (France)
	Standard status	corporate	open	open	corporate	corporate with open architecture
	Major radio manufacturers		Nokia, Motorola, OTE, Rohde&Schwarz	Motorola, E.F.Johnson Inc., Transcrypt, ADI Limited	Matra, Nortel,CS Telecom
	Possible operating frequency range, MHz	138-174; 403-423;
	Separation between frequency channels, kHz	12.5 (data transfer)
	Effective frequency band per voice channel, kHz
	Modulation type			C4FM (12.5 kHz) CQPSK (6.25 kHz)
	Speech coding method and speech conversion speed	adaptive multi-level encoding (64Kbps conversion and compression up to 9.2 Kbps)	(4.8 Kbps)	(4.4 Kbps)		(7.2 Kbps)
	Information transmission speed in the channel,		7200 (28800 - when transmitting 4 information channels on one physical frequency)			9600 (up to 32K when transmitting data in burst mode)
	Communication channel establishment time, s	0.25 (in single-zone system)	0.2 s - with individual call(min); 0.17 s - with a group call (min)	0.25 - in direct communication mode; 0.35 - in relay mode; 0.5 - in the radio subsystem	no more than 0.5	no more than 0.5
	Communication channel separation method		Time Division Multiple Access (using frequency division in multi-zone systems)	Frequency method of access to communication channels	Frequency method of access to communication channels	Time Division Multiple Access
	Control channel type	dedicated	dedicated or distributed (depending on network configuration)	dedicated	dedicated	Dedicated or distributed (depending on network configuration)
	Information encryption capabilities	standard proprietary end-to-end encryption algorithm	1) standard algorithms; 2) end-to-end encryption	4 levels of information protection	1) standard algorithms; 2) end-to-end encryption	no information

Appendix 2

Functionality provided by digital trunked radio standards systems

	Communication system functionality
	Supports basic call types (individual, group, broadcast)
	Access to PSTN
	Full duplex subscriber terminals
	Data transfer and access to centralized databases
	Direct mode
	Automatic registration of mobile subscribers
	Personal call
	Access to fixed IP networks
	Sending status messages
	Sending short messages
	Supports GPS location data transmission mode
	Facsimile
	Possibility of installing an open channel
	Multiple access using subscriber list
	Availability of a standard signal relay mode
	Availability of “dual observation” mode

Appendix 3

Fulfilling special requirements for public safety radio communication systems

	Special communication services
	Access priority
	Priority Call System
	Dynamic Regrouping
	Selective listening
	Remote listening
	Caller Identification
	Call authorized by dispatcher
	Over-the-air key transfer (OTAR)
	Simulation of subscriber activity
	Remote disconnection of a subscriber
	Subscriber authentication

Appendix 4

TETRA projects in Russia

Service region	Customer
O. Balaam	Russian Orthodox Church
Leningrad region	Leningrad NPP
Mezhdurechensk, Kemerovo region	Coal company "Southern Kuzbass"	Rohde&Schwarz Bick Mobilfunk , ACCESSNET-T
Nizhny Novgorod	Main Directorate of Road and Transport Services of the Nizhny Novgorod Region		Sepura, Motorola
Noyabrsk	OJSC Sibneft (Noyabrskneftegaz and Omsk Oil Refinery)	Rohde&Schwarz Bick Mobilfunk, ACCESSNET-T	Sepura, Motorola, Nokia
Saint Petersburg	CJSC "RadioTel"

During installation(conclusion of a contract)

Service region	Customer	Manufacturer of network infrastructure, system	Manufacturer of subscriber equipment
Baltic oil pipeline (Yaroslavl-Primorsk)	Transneft Company
Moscow	Ministry of Defence	Rohde&Schwarz Bick Mobilfunk, ACCESSNET-T	Sepura, Motorola
Omsk region	OJSC "Sibneft" (Omsk Oil Refinery)	Rohde&Schwarz Bick Mobilfunk, ACCESSNET-T	Sepura, Motorola, Nokia
Kaliningrad region	Ministry of Defence	Rohde&Schwarz Bick Mobilfunk, ACCESSNET-T	Sepura, Motorola
Samara Region ("Middle Volga")
Sverdlovsk region	MPS Sverdlovsk railway	Rohde&Schwarz Bick Mobilfunk, ACCESSNET-T
Tula region	Cherepetskaya GRES	Motorola, Compact TETRA
Northwestern region of Russia	"Transneft"
Metropolitan of St. Petersburg	Ministry of transportation
Volga region	"Gazprom"
N.Novgorod
Metropolitan of Kazan	Ministry of transportation

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MEANS OF COMMUNICATION:

DEVELOPMENT,

PROBLEMS,

PROSPECTS

MATERIALS

SCIENTIFIC AND PRACTICAL CONFERENCE

MUNICIPAL EDUCATIONAL INSTITUTION

"NOVOSELITSKA SECONDARY EDUCATION SCHOOL"

NOVGOROD DISTRICT, NOVGOROD REGION

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

The lesson-conference contributes to the growth of the teacher’s creative potential, the formation of students’ skills in independent work with various sources of information, and allows them to comprehend previously acquired knowledge in a new light, systematize and generalize it. Participation in the conference develops the ability to speak publicly, listen and analyze the messages of your classmates.

The conference materials are designed for creative use and are intended to help teachers prepare and conduct physics lessons.

FROM THE HISTORY OF COMMUNICATIONS

Communications have always played an important role in the life of society. In ancient times, communication was carried out by messengers who transmitted messages orally and then in writing. Signal lights and smoke were among the first to be used. During the day, smoke is clearly visible against the background of clouds, even if the fire itself is not visible, and at night, the flame is visible, especially if it is lit in an elevated place. At first, only pre-agreed signals were transmitted in this way, say, “the enemy is approaching.” Then, by arranging several smokes or lights in a special way, they learned to send entire 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 played a particularly important role in Veliky Novgorod. At his call, Novgorodians gathered at a veche to resolve military and civil matters.

For command and control of troops, banners of various shapes were of no small importance, on which large pieces of various brightly colored fabrics were attached. Military leaders wore distinctive clothing, special headdresses and signs.

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

Since the 16th century in Rus', the delivery of information using the Yamskaya chase has become widespread. Yamskaya tracts were laid to important centers of the state and border cities. In 1516, a Yamskaya hut was created in Moscow to manage the postal service, and in 1550, the Yamskaya order was established - the central institution in Russia 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 was developed in optical telegraphy. Towers were erected between cities, which were located at a distance of direct visibility from each other. Each tower had a pair of huge articulated wings with semaphores. The telegraph operator received the message and immediately transmitted it further, 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 St. Petersburg and Warsaw. The line had 149 towers. It was served by 1308 people. The signal traveled along the line from end to end in 15 minutes.

In 1832, Russian army officer, physicist and orientalist Pavel Lvovich Schilling invented the world's first electric telegraph. In 1837, Schilling's idea was developed and supplemented by S. Morse. By 1850, the Russian scientist Boris Semenovich Jacobi created a prototype of the world's first telegraph apparatus with letter 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 radio-telephone communications began to be introduced.

Map of Yamsk tracts of the 16th century. Postal routes of Russia in the 18th century.

COMMUNICATION CLASSIFICATION

Communication can be carried out by filing signals of various physical natures:

Sound;

Visual (light);

Electrical.

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

Electrical (telecommunications);

Signal;

Courier-postal.

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

Wired communication;

Radio communications;

Radio relay communication;

Tropospheric radio communication;

Ionospheric radio communications;

Meteor radio communication;

Space communications;

Optical communication;

Communication by mobile means.

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-postal service.

Communication can be done by transmission of information via communication lines:

In clear 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 transmission is carried out alternately in both directions.

Communication happens bilateral, in which duplex or simplex information exchange is carried out, or unilateral, if messages or signals are transmitted in one direction without a return response or acknowledgment of the received message.

SIGNAL COMMUNICATION

Signal communication carried out by transmitting messages in the form of predetermined signals using signaling means. In the Navy, signaling communications are used to transmit 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 sets of Navy signals, as well as a flag semaphore, are usually used. Telegraphic Morse code signs are used to transmit clear text and signal combinations of arches by light-signal devices.

Navy ships and vessels and roadstead posts use the International Code of Signals to negotiate with foreign ships, merchant vessels and foreign coastal posts, especially on issues of ensuring the safety of navigation and the safety of life at sea.

Signaling means, means of signaling visual and audio 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, spotlights, signal lights); c) pyrotechnic signaling devices (signal cartridges, lighting and signal cartridges, marine signal torches).

Sound signaling means - sirens, megaphones, whistles, horns, ship bells and fog horns.

Signaling means have been used since the days 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, installed 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 has also increased. In 1773, the book of signals 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. The means of light communication - lanterns and spotlights - were further developed.

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

PHYSICAL FUNDAMENTALS OF TELECOMMUNICATION

At the end of the twentieth century, widespread telecommunications – transmission of information through electrical signals or electromagnetic waves. Signals travel through communication channels - wires (cables) or wirelessly.

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. These signals are then converted into a form suitable for transmission over long distances, amplified to the required power and “sent” to the cable network or radiated into space.

Along the way, the signals are greatly weakened, so intermediate amplifiers are provided. They are often built into cables and placed on repeaters (from the Latin re - a prefix indicating a repeated action, and translator - “carrier”), transmitting signals via terrestrial communication 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 communications were considered the main one. By purpose, wired communications are divided into:

Long-distance – for interregional and interdistrict communications;

Internal – for communication in a populated area, in production and office premises;

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

Wired communication lines are often interfaced with radio relay, tropospheric and satellite lines. Wired communication, due to its great vulnerability (natural influences: strong winds, accumulation of snow and ice, lightning strikes or criminal human activity) 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-resistant, but its speed is low. Telegraph direct-printing communication has a higher transmission speed and the ability to document received information.

In 1837, Schilling's idea was developed and supplemented by S. Morse. He proposed a telegraph alphabet and a simpler telegraph apparatus. In 1884, the American inventor Morse commissioned the first writing telegraph line in the United States between Washington and Baltimore, 63 km long. Supported by other scientists and entrepreneurs, Morse achieved significant distribution of his devices 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 letter printing of received messages.

The operating principle of a writing electromagnetic telegraph apparatus is as follows. Under the influence 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 earthenware plate moved along guides using a clock mechanism.

When the electromagnet was operating, 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 an electrical circuit.

In 1841, Jacobi built the first electric telegraph line in Russia between the Winter Palace and the General Headquarters 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 St. Petersburg-Moscow railway, the government insisted on laying an underground telegraph line along it. Jacobi proposed building an overhead line on wooden poles, arguing that the reliability of communications over such a long distance could not be guaranteed. As one might expect, this line, built in 1852, did not last even two years due to imperfect insulation and was replaced by an overhead line.

The academician carried out important work on electrical machines, electrical telegraphs, mine electrical engineering, electrochemistry and electrical measurements. He discovered a new method of 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 a corresponding number of different combinations of elementary signals. Each such combination, called a code combination, corresponds to a letter or number.

Transmission of code combinations is usually carried out by binary alternating current signals, most often modulated by frequency. Upon reception, 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 transmitted information. Telegraph communications are developing in the direction of further improving equipment, automating the processes of transmitting and receiving information.

TELEPHONE COMMUNICATIONS

Telephone communication is intended for conducting oral conversations between people (personal or business). When managing complex air defense systems, railway transport, oil and gas pipelines, operational telephone communication is used, 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 audio 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 its pole pieces there is a coil with a large number of turns of insulated wire. A metal membrane is located opposite the pole pieces.

Bell's telephone receiver was used to transmit and receive speech sounds. The call to the subscriber 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 micro-bulb turns into a medical probe. By inserting it into the stomach or esophagus, the doctor examines what previously could only be seen during surgery.

Modern television equipment makes it possible to control complex and hazardous production. The operator-dispatcher monitors several technological processes simultaneously on the monitor screen. The operator-dispatcher of the road safety service solves a similar problem, monitoring traffic flows on 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 the missile forces, television makes it possible to monitor preparations for launch and launch of missiles, monitoring the condition of units and components in flight.

In the navy, television provides control and surveillance of the surface situation, overview 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, unmanned aircraft controlled by radio.

Television has found wide application in simulators.

Television systems, working 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 landings of aircraft.

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

Television development trends include expanding the range of spectral sensitivity, introducing color and volumetric television, reducing the weight and dimensions of equipment.

VIDEO PHONE COMMUNICATION

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

FELDJEGERSKO – POSTAL SERVICES

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

CONNECTION QUALITY

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

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

Communication reliability– its ability to operate reliably (stablely) for a certain period of time with the reliability, secrecy and speed specified for given operating conditions. A significant impact on the reliability of communication is exerted by the noise immunity of the communication system, lines, channels, which characterizes their ability to function under conditions of exposure to all types of interference.

Reliability of communication– 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 error to the total number of transmitted ones.

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 in developed countries, the reliability standard is 10-7 – 10-9.

Communication secrecy characterized by the secrecy of the fact of communication, the degree of identification of distinctive features of communication, and the secrecy of the content of the transmitted information. The secrecy of the content of transmitted information is ensured through the use of classification, encryption, and encoding equipment for transmitted messages.

PROSPECTS FOR COMMUNICATION DEVELOPMENT

Currently, all types and types of communications and the corresponding technical means are being improved. In radio relay communications, new sections of the ultra-high 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. Optical (laser) communications are being developed and put into practical use, primarily for transmitting large amounts of information in real time between satellites and spacecraft.

Much attention is paid to standardization and unification of blocks, components 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 converted discrete-pulse (digital) form. Digital communication systems have great advantages in creating global communication systems.

LITERATURE

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Preface…2

From the history of communications... 3

Communication classification ... 5

Signal communication... 6

Physical foundations of telecommunications ... 7

Wired communication... 7

Telegraph communication ... 8

Telephone connection ... 10

Telecode communication... 12

Internet… 12

Optical (laser) communication ... 14

Fax communication... 14

Radio communication ... 15

Radio relay communication... 17

Tropospheric communication ... 17

Ionospheric radio communication ... 17

Meteor radio communication ... 17

Space communications ... 18

Radar… 18

Television communication ... 21

Videotelephony…24

Courier-postal service… 24

Communication quality ... 25

Prospects for the development of communications ... 25

Literature ... 26

Responsible for release:

Computer layout: Press Boris

In the historical development of communication networks and services, four main stages can be distinguished (Fig. 1). Each stage has its own development logic, relationship with previous and subsequent stages. In addition, each stage depends on the level of economic development and the national characteristics of the individual state.

Figure 1.8 Stages of development of communication networks and services.

The first stage is the construction of a public telephone networkPSTN (Public Switched Telephone Network). The telephone network is the longest, most extensive and accessible telecommunications network. For a long time, each state created its own national analogue public telephone network (PSTN). Telephone communications were provided to the population, institutions, and enterprises and were identified with a single service - the transmission of voice messages. The terminal device of the telephone network was the telephone set, and the computer performed only computing functions. Then, for a long time, the development process followed the path of using public telephone networks to transmit signals from computers, and data transmission began to be carried out over telephone networks using modems. When the exchange of information from computers reached a significant level, it became expedient to create telecommunication networks, which are a set of telecommunications means for delivering information to remote subscribers (users) and means for storing and processing the information to be transmitted. This set also includes software that provides users with one or more types of services: exchange of voice messages (including traditional telephone communications), data, files, fax messages, video signals, access to various databases, etc. However, even today the telephone remains the main communication service, bringing operating organizations more than 80% of revenues. The installed capacity of the domestic public telephone network exceeds 27 million numbers (planned to reach 40-45 million); in total there are over 800 million telephone sets in the world.

The second stage is the digitalization of the telephone network. To improve the quality of communication services, increase their number, increase control automation and equipment manufacturability, In the early 70s, industrialized countries began work on the digitalization of primary and secondary communication networks. Were created integrated digital networksIDN (Integrated Digital Network) , also providing mainly telephone services based on digital switching and transmission systems. Currently, in many countries, the digitalization of telephone networks has practically ended.

The third stage is integration of services. Digitalization of communication networks has made it possible not only to improve the quality of services, but also to increase their number based on integration. This is how the concept came about integrated services digital networkISDN (Integrated Service Digital Network). The user of this network is provided with basic access (2B+D), through which information is transmitted over three digital channels: two B channels with a transmission speed of 64 Kbit/s and a D channel with a transmission speed of 16 Kbit/s. Channels B are used for voice and data transmission, channel D is used for signaling and data transmission in packet switching mode. For a user with greater needs, a primary access containing (30B+D) channels can be provided. The ISDN concept is rapidly conquering the telecommunications market, but ISDN equipment is quite expensive, and the list of ISDN services exceeds the needs of the mass user. This is why service integration is beginning to be replaced by the concept of the smart grid.

Stage four - smart networkIN (Intelligent Network). This network is designed to quickly, efficiently and economically provide information services to the mass user. The required service is provided to the user when he needs it and at the time when he needs it. Accordingly, he will pay for the service provided during this time interval. Thus, the speed and efficiency of service provision also makes it possible to ensure its cost-effectiveness, since the user will use the communication channel for significantly less time, which will allow him to reduce costs. This is the fundamental difference between the smart grid and previous networks - the flexibility and cost-effectiveness of service provision.

The state of the Russian telephone network does not meet modern requirements. Half of the telephone exchanges on the PSTN have already fulfilled their depreciation periods and require updating. Therefore, the development of telecommunication networks and services is associated with the re-equipment of automatic telephone exchanges. According to plans for the development of the PSTN, it is planned to put into operation significant numbering capacity in the near future through the installation of new electronic (digital) switching stations and the replacement of outdated automatic telephone exchanges of decade-step and coordinate systems. At the same time, analog switching and channel-forming equipment is also retained on telephone networks. A representative of the new generation of automatic telephone exchanges is the switching station KSM-400 manufactured by Morion OJSC.