UA64839C2 - Microwave television and radio information system (mitris) - Google Patents

Abstract

The present invention relates to the special communication facilities designed for transmitting analog and digital television programs. The proposed microwave television and radio information system contains a subsystem for receiving and processing information messages, a base station, and subscriber terminals. The base station contains a multichannel microwave transmitter, a transmitting antenna, and a communication line between the transmitter and the antenna. The microwave transmitter contains a frequency modulator, a frequency multiplier with an IMPATT diode, an output unit, and a filter in each of the transmitter channels, and a unit for synchronization of the transmitter channels. Additionally, the proposed system contains a unit for forming signal transmitted over the digital communication link, repeaters, and relay stations; and the base station contains a coder and a computer with software that is designed for monitoring payments for communication services and provides protection against unauthorized access to the system. The subscriber terminal contains a transmit-receive or receiving antenna, a transceiver or receiver, and a subscriber-to-terminal interface. The advantages of the proposed system are the following: increasing communication range, decreasing unfavorable effect of system technical facilities on environment, the possibility of two-way communication, increasing the reliability and reducing the cost of the system equipment due to use of production-type elements, enhancing the degree of unification of the system equipment elements, the possibility to realize the modular structure of the system, reducing the period required for switching on and off the system, the possibility of interfacing the system with existing cable and fiber-optic telephone systems as well as with the "Internet" information network, increasing the system capacity when transmitting massages, increasing noise immunity in transmitting signals within the system, reducing the power of transmitted radio signals, reducing the system power consumption.

Description

transmitter, a transmitter with independent barrels and a group transmitter with one output amplifier are distinguished.

When first built, each MTRM channel has its own separate transmission trunk, independent from the others.

The trunks are combined in a frequency adder directly connected to the antenna system. This construction allows you to take into account the features of a specific transmitted channel (modulation method, frequency stability, etc.) and achieve the highest possible quality of the broadcast signal. A transmitter with a group construction of trunks is cheaper than a transmitter with independent trunks, but has a number of disadvantages associated with strict requirements for the parameters of a single output broadband power amplifier for all channels. Here, after the modulators in the converters, the signals are shifted up in frequency, summed up in the combining device and sent to the broadband power amplifier. Such a construction is convenient for the broadcasting of television and radio programs in the long-wave part of the microwave range (extremely high frequency range), where it is possible to create such an amplifier and its reliable operation while fulfilling all the requirements imposed on it, especially in terms of intermodulation levels and unevenness of frequency-phase characteristics . As the frequency increases, the group construction of the transmitter becomes inefficient.

As an antenna system, a feeder path based on waveguides or coaxial cables and antennas is used, which has narrowed directivity patterns (DP) in the vertical plane in order not to create interference with satellite receiving installations. Antennas can be omnidirectional with a circular DS and horn sector antennas, with openings from 30 to 270". The use of one or another type of antenna is determined by the needs for the size of the territory coverage, the allowed broadcast sector, restrictions imposed by the working frequency range used, the features of the territorial television and radio information network being created .

For high-quality reception of FM analog and FM digital television and radio information signals of satellite channels, a teleport is used, which includes a number of reception complexes with antennas with a diameter of 1.5 to 5 m.

Mainly, the infrastructure of MTRM is formed by distribution radio lines that connect studio centers with

CE and BS, with CE and among themselves, as well as CE with public telephone networks and various local computer networks. Radio lines are built mainly on the basis of microwave small-sized radio relay stations (PRO) and, less often, dedicated satellite channels. However, due to the large volume of information transmitted in the MTRM (dozens of analog TV channels, digital streams with total transmission speeds of up to 100 Mbit/s), fiber optic communication lines (FOCL) have recently been used as distribution lines, where local conditions allow. This is especially important for digital MTRMs

of the microwave range, which are designed to provide a full set of modern digital access services to both computer networks and public telephone networks, as well as to multimedia data banks.

The purpose of repeaters in MTRM is similar to their purpose in traditional broadcasting - they must serve those parts of the coverage area of the Tse radio transmitter, where the reception of broadcast signals with adequate quality is not ensured due to the shielding effect of the terrain, and also expand the service areas of Tse broadcasting.

Subscriber stations (AS) of reception in MTRM have the greatest variety. They can be individual or collective, can be combined with standard satellite tuners or made only for a certain type of MTRM, can be intended exclusively for receiving TV programs or data streams, etc. It is obvious that the variety of ACs is quite natural and is determined by the type of MTRM, the purpose of a specific subscriber terminal and its price.

Depending on the antenna systems used by base stations, the MTRM broadcast zone can be circular (with an omnidirectional antenna) or sectorial (with a corresponding antenna or antennas). In the circular zone of action, the BS is located in the center of the circle, the radius of which is called the range of the system. The value of such a radius strongly depends on the weather conditions and the topography of the area, so the radius of action usually means the distance from the BS to the point of reliable reception in the worst weather conditions for this area. When calculating the interference between neighboring BS broadcast zones, the concept of the maximum radius of action is used, which is defined as the largest distance from the BS to the point of possible reception of the MTRM signal without taking into account the attenuation of radio waves in hydrometeors and the influence of the landscape surface.

In the case of a circular broadcasting zone, the broadcasting frequency of the closely located BSs (or their repeaters) must be selected, as shown in Fig.1. Shown here are a series of circular zones numbered 1 through 7 that correspond to seven different operating transmission frequencies. Polarization and temporal distribution of transmission channels is recommended to be used within broadcast zones, and not to provide resolution between adjacent zones, so that there are no prerequisites for the occurrence of accidental cross-interference of different zones.

The limited frequency resource inherent in any radio system (but to varying degrees) and the need to broadcast in a certain spatial area while ensuring maximum efficiency in the use of transmitter power determined the organization of broadcasting by sectors. At the same time, the broadcast zone (which includes a circular one) is divided into an even number of corner sectors - four, six, eight, etc., in which transmitters with antennas with a sectorial pattern are installed. Sections through one can be served by the same (frequency) transmitters, which increases the efficiency of using the frequency band by two, three, four times, etc. As can be seen from Fig. 2, the greatest danger of inter-sector interference lies in the area close to the transmitter, where it is possible to have a high density of radiation from the side lobes of sector antennas, which places high demands on the latter to ensure their suppression. Detuning of signals in adjacent sectors is performed using frequency diversity, polarization change, or modulation means.

The efficiency of using the frequency band and the power of the transmitters for MTRM in the microwave range can also be increased by organizing the network according to the cellular principle, based on the fact that the broadcasting area is divided into small cells, a kind of cells, each of which is served by a separate transmitter. Its radius of action, as a rule, is small - up to 3 km.

Each such cell contains one base or relay station that operates in a specific frequency channel and is connected to a neighboring cell, thus creating a complete service area.

The relay station has two transceivers and is located in the center of the cell. These two transceivers are called base or relay depending on the function they perform: a base transceiver uses an omnidirectional antenna to serve subscribers in its cell, and a relay uses a directional antenna or cable channel to communicate with a base or relay station in a neighboring cell . Cellular construction for MTRM

The microwave range is the only possible one. This is due to the rapid attenuation of millimeter waves in the atmosphere.

The removed cells are connected by a fiber-optic communication line (FOLC) or another high-speed line.

Ring structures of MTRM can be created according to the "ring within a ring" principle, which makes it possible to expand the cellular network around the perimeter of the existing area of operation, forming an outer ring of BSs connected by a high-speed communication line. At the same time, all rings have access to one common MTRM center.

The star-shaped construction structure is the most characteristic for MTRM and is recommended when forming a network of a number of independent MTRMs consisting of one CA and BOS located around it. This structuring makes it possible to create a locally distributed network, which can include remote MTRMs, Fig. 3.

However, the construction of a large-scale television and radio information network exclusively on the basis of MTRM is in some cases unprofitable. This is due, first of all, to the fact that in any place there is at least one functioning information system that can largely satisfy the needs of some part of its users. Secondly, it is obvious that in urban areas with a high population density and high-rise buildings, in the presence of a developed communication infrastructure, the most effective use of the cable television network (MKTM) is. Thirdly, unfortunately, currently part of the population is financially unable to afford to use the services of paid television and radio broadcasting. And, finally, and fourthly, the increase in the flow of transmitted information requires high-speed communication lines, just as in terrestrial highways, VOLZ are used, and in global intercontinental highways - satellite communication lines. Thus, in reality MTRM to one degree or another always interacts with the TV and radio information networks that are in its area of influence and neighboring areas. At the same time, in a number of cases, the mutual functioning of the latter with MTRM allows to overcome their inherent shortcomings, thanks to the advantages of MIRM technology. MTRM and MKTM can fully provide high-quality television and radio information to any administrative district with arbitrary construction and topography.

The American multi-channel multi-point distribution network MMO5 - Miyispappe was one of the first among MTRMs to emerge! Miyiroipi Oivipirshiop Zuziet. (Y.A. Labunsky, K.N. Havrish, Baindurashvili

H.L. The MMO5 system of Miemuzopis IPS., (USA) for the distribution of television programs. //

Material! 7th International Crimean Microwave Conference Crimea-97 "Microwave Technology and Telecommunication Technologies", Sevastopol, September 15-18. 1997 - Sevastopol: WEBER. 1997. - P. 318-319). Despite the fact that the frequency range used by it refers to the short-wave part of decimeter wavelengths, the construction of the system and the technical solutions included in it make it possible to easily retune it to a higher frequency range (at least up to 5 GHz).

Based on this, it is considered as a microwave system.

The emergence of the MMO5 network is associated with the sixties, when Canada and the United States created the international federal television standards service (ITE5 - Ipiegpayopa! Redega! TeIemiziop Zegmise), which determined the placement of 31 television channels for local distribution systems of television broadcasting in the 2500-2690MHz frequency band. This broadcasting system was intended to provide telecasts to small towns and communication between regional telecentres. Two channels in the 2150-2162 MHz band were allocated for services

МО5 (MyShroipi Oiwiirsiop Zeguise - multipoint distribution service). These systems, which broadcast only one channel of pay TV for consumers, surprisingly caught on quickly and by the end of the 1970s and beginning of the 1980s served about 1 million people. subscribers MKTM, which is rapidly developing, has so far provided consumers with 10-20 channels for the same subscription fee, which forced MOH companies to look for ways to expand the market. In 1983 Federal Communications Commission (ECS - Redega! Sottipisaiope Sottivviop)

The USA created MMO5 in the 2500-2686 MHz band with the possibility of broadcasting up to 30 television programs.

In the early 1990s, MMO5 systems worked on all continents of the globe, serving from 100 to 250,000 people. subscribers In the USA until 1997 MMO5 has already been covered by more than 5.5 million people. subscribers On the nearest

In the East and in Australia, systems covering an area of up to 10,000 km were tested, and television signal retransmission systems were tested, allowing to combine up to 25 transmission centers into a single network.

MMO5 is a broadband transmission complex that broadcasts information that is fed to its input in a frequency band with a width of up to 200 MHz, and this makes it possible to transmit up to 24 programs in the FESAM standard. The input of the system can receive signals from receiving television antennas in the meter and decimeter ranges, from a satellite receiving system or from a local television studio. Next, the group signal is filtered and converted into the range of 2500-2686 MHz, amplified and fed to the transmitting antenna. Since signal reception at these frequencies is possible only within the direct line of sight, it is very important to place the transmitting antenna at a sufficient height to ensure quality service of the required area.

The receiving part of the equipment is compact and consists of a small receiving antenna and a step-down converter that transfers the group signal from the 2.5 GHz range to the required range of meter or decimeter waves. Since the transmission uses amplitude modulation (AM), which is adopted in broadcast television, the output of the receiving converter emits signals of television broadcasts in the usual form. The output of the converter can be connected directly to the subscriber's TV (in rural areas, in cottage-type buildings), to the home distribution network (in multi-storey buildings) or to the input of the main station of the local cable network (in complex multi-storey buildings, if a receiving antenna is installed on each the house is impossible).

The radius of the MMO5 service area is determined by the height of the suspension of the transmitting antenna, the power of the transmitter, the number of transmitted channels, losses in the antenna-feeder path and the gain coefficient (CP) of the transmitting and receiving antennas. It is technically possible to serve a zone with a radius of 50 km. The system provides a sufficient range depending on the power of the transmitter and the height of the suspension of the transmission antenna with a circular DS (KP equal to 11.5dB) for an 8-channel system while ensuring a signal-to-noise ratio of at least 49dB (professional TV signal quality) on the perimeter of the service area.

Group transmitters in most cases cannot provide the required broadcast quality for a medium-sized city. Moreover, with an increase in the number of programs fed to the input of the group transmitter, the range of the system will decrease with the equivalent value of the signal-to-noise ratio at the perimeter of the service area. For example, when feeding an ideal group 100-watt transmitter with 16 TV programs to the input, the power per channel will be 1W, and the radius of the service area is 4.7km. Thus, with some cost savings on the transmitting side, the operator will inevitably incur additional costs on the receiving side due to the need to use more sensitive antennas.

It must be taken into account that the cost of a receiving antenna with a gain of 24dB is almost twice as high as antennas with 18dB, therefore, if the purchase of a group transmitter requires several hundred antennas, then before deciding on such a step, it is advisable to study the city map again, taking into consideration promising areas of cottage development.

On the market of countries - the former republics of the USSR, for example, the cost of an 8-channel MMO5, depending on the power of the transmitters, varies from 40 to 140 thousand dollars. USA. The radius of the coverage area varies from 2.8 to 19 km. MMO5 systems are offered by a number of companies - such as Miem5opis5 IPS., USA, Etsee

Vgoadsavzi Rhodisib5", USA, "Saiyogpia Atriyeg", USA, "Sotulame" of concern "Tpotsazi" USA, "AOS 15

Sogrogayop", USA, "Viewonics-R" (Russia - USA) and others.

The main disadvantages of MMO5 are the noticeable limitation of the frequency range, high levels of transmitter power and the use of AM. These shortcomings are mostly determined by the outdated concept of MMOZ as a simple extension (supplement) of broadcast broadcast television. Indeed, the presence of AM facilitates the reception of standard TV signals by subscribers, but it requires high transmitter powers, and the use of the 2.5 GHz range was clearly determined by the level of development of communication technology at the time of the emergence of MMO5 (60-70s of the XX century). The use of high-power transmitters is also dictated by the desire (similarly to traditional broadcast broadcasting) to achieve coverage of the largest possible broadcasting area. This leads to the problem of violation of environmental safety in the near area of the transmitter.

Recently, MMO5 manufacturers have been trying to adapt their products to the needs of modern users (integrating additional broadcast channels, offering Internet services, etc.), as well as finding their "niche" in small towns where there is a shortage of television and radio programs.

However, it must be emphasized that it was MMO5 that was a pioneer in the creation of MTRM. It was she who showed and proved the advantages of MTRM over traditional broadcasting networks and its prospects. Right now this system is the most common among MTRM.

The development of the millimeter range of wavelengths, the noted shortcomings of MMO5, the increase in television channels and the growing needs for MTRM services led in the second half of the 1980s in the USA to the creation of the I MO5 network (I wasa! based on frequencies of 27.5-29.5 Hz. (Chaskzop V.M. Sopvzidegaynop ip She cyze oi soriapag uu"amedtside og tiShteg(eg-mame ipiedgaseai sigsiiiv5. / IEEE Tgap5. MTT. 1986. Moi. 34, Mo12. R. 1450-1456). The main advantage

IGMO5 consisted in the fact that for the first time the waves of the microwave range, which were previously considered unsuitable for television broadcasting, were used.

For some time there were fears that the use of new technology would affect the quality of the transmitted signal. However, it turned out that interference and interference on the signal reception line between the transmitter and the receiver do not cause problems, since the transmission of signals at such frequencies tends to bounce off the interference with almost no loss of quality. Moreover, it turned out that it is possible to receive a signal reflected many times on an individual receiving antenna.

The development of the cellular construction of television and radio broadcasting, which operates in the 28 GHz range and uses the YIMO5 technology, belongs to the American company "SeishShag Miziop" - SM. The essence of the system consists in the installation of a whole network of transmitters with certain radii of action in the metropolis, which work according to the cellular (cellular) principle.

Equipment for GMO5 is offered on our market by well-known US companies - "Seiyshag Miziop apa

TeIesottipisaiop5", "I oer rappeg5", "I isepi Tesppoiodiez" and "ZTE". It should be noted that the 28GHz broadcasting range is allowed only in America, however, European companies also offer their equipment for

GMO5, for example, the company "RpPiirv".

In the equipment for I/MO5 of the company "RPiir5" ("Philips"), the system of each base cell consists of a broadband transmitter and internal receivers. The transmitters use a modular approach that allows you to easily add additional channels or upgrade the transmitter to receive, for example, interactive services. The transmitters do not require any modifications and adjustments, have built-in diagnostics and emergency redundancy. External units transmit 8 video channels, and at the same time there is one free reserve channel. All channels for multiplexing 8-41 can be combined into a package (group), for example 48-46. The transmitter of the internal base unit has an interface for managing built-in diagnostics and maintenance. The external and base units are interconnected using one coaxial cable and one power cable.

Subscribers' receivers are equipped with a standard antenna with a diameter of 15 cm. Other sizes of antennas are also available (optional). The miniature size of the antenna systems contributes to the ergonomics of the receivers, they are easy to install. The receiver-converter (down-converter) processes the signal in the format of a satellite signal, so the receiving units (satellite tuner), which are currently in mass production, can be used without modifications.

In Europe for analog TV and radio broadcasting in 1989. dedicated frequency range of 40.5-42.5 GHz.

The MTRM developed for these purposes was named MMO5 (Miyiroipi Mideo rivigirshiop Zuvziet - a multipoint distribution system of (tele)vision (Riidgit M., Sagmag A.O., Vagtev V.5. MMO5 402Н2 Miyisnappe! TM yu pote. // 20-4y Eshgoreap Mistojame Sopiegepse, Vidarezi, Zeri. 10-13. 1990: Oidevzi, pp. 299-304).

The MMO5 network uses frequency modulation (FM) and is designed to serve small settlements (from 10 to 100,000 people). Taking into account the local (European) average annual precipitation density with a transmitter power of 100mW per channel and a noise coefficient of individual receivers of 8-12dB, such a system was designed to transmit 15-25 high-quality TV channels at a distance of up to 3.3 km.

The MUZ consists of two main parts: the distribution central station (TC) and a variety of receivers of individual users (subscribers). The CS includes a satellite teleport (for receiving satellite TV channels), receivers, a cable port for receiving regional TV channels, a local TV studio, transmitter equipment based on Hanna generators and a horn antenna with a large opening angle. BS is located on the periphery of the service area. Individual receivers are equipped with a parabolic antenna with a diameter of about 15 cm and are, in fact, converters with an intermediate frequency of 950-1750 MHz. This allows you to use a standard satellite television tuner to select television channels and transmit them to the television receiver. The cost of a subscriber's tuner with an antenna is 50-100 dollars. USA.

Since its inception, MMO5 has proven to be a highly efficient system both in terms of rapid deployment and distribution of television broadcasting, and in terms of cost. The new MMO5 systems are built similarly to the GMO5 cellular structure, but in the higher frequency range - 42GHz. The most attractive quality of the new MUO5, as well as /MO5, is the large bandwidth provided - 2 GHz. This is almost an order of magnitude greater than the IMO5 terrestrial broadcast range.

However, the propagation of signals in the area of 40 GHz has its own characteristics, which largely determine the specifics of building MMO5 networks. Thus, the attenuation of millimeter waves in the atmosphere is much higher than for meter and decimeter waves, and strongly depends on climatic influences. Another feature of waves in this range is the straightness of their propagation: they are not able to go around even small obstacles, but, on the contrary, reflect from them almost without distortion. Practice has shown that at a frequency of 40 GHz, signals that have undergone 4 times reflection are received satisfactorily. This property can be used in the design of high-frequency signal distribution systems.

The small radius of propagation of millimeter waves determined the application of the MMO5 technique in networks with low-power transmitters built according to the cellular principle. The wide bandwidth combined with the cellular structure make this technique suitable for the organization of interactive multimedia networks, including television, telephony, video conferencing, high-speed Internet access and data transmission. MMO5 equipment can be used both independently and as part of hybrid cable networks.

Both analog and digital methods of information transmission, as well as various types of modulation, can be used in MUO5 networks. However, for the purposes of building multimedia networks, the development of purely digital systems compatible with the ОМВ-С or ЮОМВ-5 standard is relevant, which allows the use of ММО5 equipment in hybrid television networks, instead of a coaxial cable for distributing the signal to subscribers. In addition, it makes it possible to use standard satellite digital receivers.

A comparison of the two system options reveals the advantages of their use. So, in the "cable" version, 64-KAM modulation and the bandwidth of ZMHC channels are used, and in the "satellite" version - modulation

ORBZK and channel width 36-40 MHz. According to a rough estimate, the systems of the first option allow sending four times more information, but their radius of action with the same amplification of the transmitting and receiving equipment is also approximately four times smaller.

When testing two MMO5 systems produced by the Italian company "Tesppozubziet", in which the same antennas and transmitters of the same power were used, and both systems worked in the 1.2 GHz band, the "satellite" version of MMO5 allowed transmitting up to 30 TV channels and provided signal reception on a 25-centimeter horn antenna in a radius of 10 km, and "cable" - up to 100 channels, but at a distance of only up to 4.5 km under the condition of reception on a 60-centimeter antenna. The "cable" option is more suitable for interactive systems with the transfer of large volumes of individual information and services such as video on demand, the implementation of which requires a very wide spectrum.

It is also convenient for organizing the "last mile" of cable networks. In this case, there is no need to demodulate and demultiplex the signal. The width of the MMO5 frequency range makes it possible to simultaneously convert the entire spectrum of the signal coming from the cable into the millimeter wave range. On the receiving side, the spectrum is transferred back into the 50-860 MHz band and fed to a standard cable receiver. The "satellite" version of MMO5 also has its advantages. It is more suitable for satellite signal transmission, especially in areas with low building density. In addition, and this is the most important thing, cells of a larger radius are formed with this option, which makes it possible to use transmitters of lower complexity and cost.

The MMO5 multimedia network is being built on the basis of the main station. The most diverse sources can be used in the formation of information flows: the Internet, broadcast, cable and satellite television channels, various local sources of information. Analog signals are converted into digital form in MPEC-2 encoders. Formation of service information, channel coding and modulation are carried out in accordance with one of two standards - OMV-S or OMV-5.

After the formation of digital packets, the channels are modulated and combined for delivery to broadband transmitters. It is also possible to use individual transmitters. In the transmitter, the signal spectrum is transferred to the 40 GHz region, amplified and transmitted to the antenna. BSs can be equipped with a set of sector antennas. This allows you to increase the power of the transmitted signal, as well as increase the number of subscribers due to frequency reuse and polarization change.

The power of solid-state amplifiers used in MMO5 transmitters is very small. In transmitters with independent trunks, it is measured in tens of milliwatts, and in group transmitters designed to transmit hundreds of channels - in units of watts. The signal can be sent to cellular transmitters by fiber-optic or relay lines, or by means of the MMO5 itself.

Transmission part of the system. An antenna mounted on the wall of the building, a low-noise converter and a standard receiver (tuner) are installed at the subscriber. Antennas of various designs are used for reception - horn, microstrip or parabolic. Signals of the millimeter range are practically not subject to impulse interference and ingression noise, which can create major problems when receiving signals of the ether range. The main source of possible interference is the reflected signals of one's own transmitter. In order to maximally insure against unwanted reception of reflected signals, receiving antennas with a DC width of up to tens of seconds are used. For microwave waves, such a narrow DS can be provided by very small antennas.

Frequency transfer from the millimeter range to the decimeter range is carried out with one or two transformations. At the same time, problems are possible due to the high absolute instability of the high-frequency local oscillator of the converter and the strong deviation of the frequency of the transmitted signal (this is especially critical for digital information). Their solution can be stabilization of the local oscillator frequency by a pilot signal introduced on the transmission side into the general flow. This principle is used, for example, in the systems of the company "Technosystems" that are compatible with the OMV-O standard.

The up-conversion of the signal on the transmit side must be two-stage. First, the frequency is transferred to the range of 2.3-3.3 GHz. At this stage, the phase auto-adjustment of the local oscillator frequency of the converter and the introduction of a pilot signal synchronized in phase by the same highly stable source are used. At the second stage, the frequency is transferred to the 40 GHz range. On the receiving side, the signal is converted in the following sequence: first, the frequency is converted into the range of 2.3-3.3 GHz, after which it enters the second converter with phase auto-adjustment, where the pilot signal entered on the transmitting side is used as a reference.

The signal in MMO5 can be transmitted from cell to cell according to the "from superior to subordinate" principle. As a rule, the sources of programs and data are located on the CA of the main cell.

In a real system deployment, trees and buildings will block the signal. In this regard, special microcells operating on the principle of a deflecting beam are used. The signal is received from the main cell, amplified, changes polarization and rebroadcast. Microcell transmitters are operated only in "shadow" zones, thus it is possible to avoid interference effects without affecting the basic structure of the cells.

Summing up, it is possible to summarize the general advantages and disadvantages of the presented MTRM ranges of 29 and 42 GHz.

The main advantage is the already mentioned wide range of frequencies, which allows you to transmit huge streams of information. It is he, in combination with a small distribution radius, that makes MMO5 and MOB networks the most suitable for the organization of multimedia networks. The efficiency of using frequency resources can be further increased due to the use of sector transmission antennas.

It is also necessary to note the environmental safety of the MMUO5 and GMO5 networks. They operate with high-frequency low-power signals that are not dangerous for the human body. In addition, their construction does not affect the surrounding landscape and buildings in any way.

The disadvantages of MMO5 and GMO5 include a strong dependence of the range of their action on weather conditions, primarily on humidity. In this regard, the determination of the girth radius by one cell requires long-term experiments in each specific geographical area. It is also necessary to determine the configuration of the distribution of reflected signals in the conditions of a specific building, taking into account the fact that a constant change in the radius of action due to a change in weather conditions leads to the same constant changes in the entire configuration.

In 1991 in Ukraine, the appearance of the first Ukrainian MTRM - microwave integrated television, radio and information system MiITRIS is determined. (T.N. Nartnyk, V.N. Denisenko, M.E. Ilchenko, etc.

Microwave integrated television and radio information system. // Radioelectronics. - 1999. - T. 42. - Me11. - P. 40-50. - (ex. university). During its creation, the disadvantages and advantages of existing ones at that time were taken into account

MTRM, as well as prospects for the integration of national information systems into the European infrastructure.

When developing the system, the levels of electromagnetic fields, the boundaries of the sanitary protection zone and the zone of building restrictions in the places where television and FM radio broadcasting equipment are located were taken into account. According to the sanitary passport for 24-channel MITRIS, the borders of the zones with the maximum permissible level of energy flow density up to 2.5 μW/cm? according to the main radiation, they should be distant from the antenna at a distance of 5 m, while lateral radiation in the sectors of angles of 45" from the maximum radiation is practically absent.

Environmentally safe MITRIS, based on the latest information technologies, is focused on the construction of integrated networks that ensure the subscriber's connection with the outside world and provide him with such services as multi-channel television and radio broadcasting, access to the Internet and digital telephony, transmission of paging signals, participation in teleconferences, distance education, security and fire alarms, centralized notifications by the Ministry of Emergency Situations and other departments, collection and processing of departmental technological information and

MITRIS includes a central station (CS), a set of base stations (BS), subscriber terminals, and distribution lines. CS in MITRIS is designed to receive incoming information, which is subject to further distribution and processing (if necessary), to form and broadcast a packet of information signals. The station includes: a MITRIS receiver-transmitter, which contains an HF transceiver module with modulators and demodulators, an antenna system, a satellite television reception complex - a teleport, distribution lines and fiber-optic communication lines (VOL3Z), data reception equipment with Internet using Oigesi RS technology, equipment for connections with TV and radio studios, power supply complex. Signals of satellite television and radio programs are received by the teleporter and fed at the level of video and audio signals to the inputs of the modulators of the corresponding channels of the transmitter. Similarly, the inputs of the corresponding modulators receive signals from TV stations, TV studios, and public telephone networks. In the transmitter, the signals are modulated, converted in terms of frequencies and levels, amplified, collected into a group signal and radiated into the ether through the antenna. The power supply complex is designed to ensure uninterrupted power supply of station equipment in various situations. Digital and analog channels are broadcast at different frequencies and have independent channel-forming equipment of the modem part.

MITRIS, unlike MMO5, works in the higher frequency range - 11.7-12.5 GHz (large channel capacity is used accordingly). At the same time, the use of an FM signal allows you to use low, environmentally safe levels of radiated power - 50 mW per channel (500-1000 times less compared to MMO5). This provided additional opportunities:

- first, to get a huge energy gain in terms of power consumption and use low-power transmitters; secondly, to sharply reduce the cost of equipment in connection with the serial production of satellite television components. By the way, it is this approach that allows you to broadcast digital signals of satellite television without large additional costs.

When choosing the operating frequency range for MITRIS (12 GHz), the following main factors were taken into account: - the MITRIS network intended for. the transmission of several dozen (30-40) television programs requires the occupation of a total frequency band of about 1.5 GHz, and high-quality characteristics of the antenna-feeder and amplifier-converter paths are relatively easy to achieve in a frequency band that is about 1095 from the carrier, so the range of operating frequencies should be in the zone of 10-15 GHz; - the radio communication regulation allocates frequency bands in the range of 10.7-14 8 GHz for fixed and radio broadcasting services, which include MITRIS, however, the restrictions of the Radio Communication Regulation, the National Table of Radio Frequency Band Allocation of Ukraine, as well as the Ministry of Defense of Ukraine narrow this area up to 10.7-13.5 GHz; - there is no resonant absorption of radio waves in the specified frequency range, and the increase in attenuation of the latter is compensated by some increase in the potential of radio lines (adaptation to the conditions of radio wave propagation); - the level of natural and industrial interference in this frequency band is significantly lower than in the band where the MMO5 system works, and not much higher than in the I band of MMO5; - the dimensions and weight of the elements of the antenna-feeder path and microwave devices are small (the dimensions of the cross-section of the standard used waveguide are 19x9.5mm), and to obtain a narrow DS of the order of 5-7" the diameter of the parabolic antenna is required no larger than Zb0cm, since with such a diameter a short wavelength (less than 3cm) allows you to reach the KP of the antenna near the ZOdB, due to the fact that the mass of small-sized devices can be reduced by using metallized supporting structural elements made of light ceramics, composites, etc., and also taking into account , that Ukraine has a significant scientific, technical and production potential for the creation of devices of this range and systems in general, the choice of the 12 GHz band gives the opportunity to use for the receiving and transmitting devices of the MITRIS network cheap elements and devices of satellite television receivers - both produced by domestic enterprises and those which are sold on the world market in huge quantities at low prices and which today have high values of the parameters (yes, the retail price of the 11.7-12.5 GHz converter with noise and gain coefficients according to 1 and of the order of 30-40dB is 20-50 dollars. USA); - the requirements for the accuracy of manufacturing elements and devices are higher than for the 3-6 GHz bands, but they are acceptable (for example, the deviation of the surface of the antenna mirror from the nominal should be 1-1.5 mm, which is feasible with standard technologies).

Until now, the MITRIS network, which is a complete complex of distribution of television channels, is similar in structure to satellite systems. An antenna, converter and tuner are also required to receive the signal in it. However, unlike satellite television systems, the MiITRIS transmitter is located on Earth. MITRIS can receive high-quality signals for subscribers in their direct line of sight at distances: up to 5 km - only on the converter irradiator (without an antenna mirror); up to 15 km - for an antenna with a diameter of 20-25 cm; up to ZOokm - for an antenna with a diameter of bosm; up to 50 km - for an antenna with a diameter of 90 cm.

At the same time, the following technical parameters of MITRIS are maintained:

Operating frequency range, GHz 11.7-12.5

Bandwidth of one radio channel, 18 MHz

Frequency grid step, MHz 28

Type of modulation Frequency

The maximum number of channels of color TV or digital streams with speed

ZAMBit/s. 43

Power emitted by one radio channel, W 0.05

Polarization of radio channels Linear

The number of sound subcarriers (each radio signal in the frequency band 5-8.5 MHz up to 4

The stability of the local oscillator in the operating temperature range of 50...60"C is 2.5-1079

Suppression of the local oscillator signal in the spectrum of the output signal, dB, not less than

Suppression of harmonic and combination signals at the output of the transmitter, dB, is at least 10)

The video signal-visometric noise ratio at the limit distances when control signals are applied to the input of the transmitter, dB, not less than: on a professional receiver 54 on a household tuner 49

The noise factor of the receiving converter, dB, is not worse than 1.0

The width of the DS of the transmitting omnidirectional antenna, in the horizontal plane 360 in the vertical plane 4

KP of the transmitting antenna, dB, not less than 16

Losses in the transmission feeder path, Db 0.05

Power supply: voltage, M 220 frequency, Hz 50

Energy consumption, W per channel, no more than 40

Dimensions of the 24-channel transmitter together with the transmission antenna, m 1.0x1.6

Mass, kg, not more: transmitter for one radio channel 1.5 transmission antenna 25

The radius of the sanitary protection zone in the main petal of the DS, m 5.

As practice has shown (in particular, experimental operation of MITRIS in Kyiv and other cities of Ukraine), combining MITRIS with the main cable television stations into a single system is the most rational way to create an integrated network, taking into account economic and technical aspects. Thus, despite the complex topography of the area and the different level of development of Kyiv, the combination of cable television with MITRIS allowed broadcasting TV channels with excellent quality to any district of the city and suburban area.

With the use of MITRIS, programs of various cable television operators are expected to be exchanged

of Kyiv, as well as the broadcasting of television programs and the organization of live broadcasts of other television companies. Such experimental broadcasting is planned to be carried out by the Obryi and Delta television companies, delivering their programs with stereophonic accompaniment to these systems.

The National Television and Radio Broadcasting Council of Ukraine has approved a list of 24 Ukrainian, Russian and Western European television channels broadcasting the best programs using terrestrial television and seven satellites for retransmission using MITRIS. The organization of television and radio information broadcasting using MITRIS is a commercial project designed to encode programs and generate income through the collection of subscription fees. The entire package of programs will be divided into three conventional parts, one of which (state television channels) will be broadcast in open form, and the other two (commercial channels) will be encoded. Approximately, the monthly fee for one of the coded packages will be 16-17 hryvnias, and in the case of purchasing both packages - 13-14 hryvnias each. per package

The transition of television and radio broadcasting to a digital basis, the increase in the number of Internet users, the rapid development of computer telecommunications and the successful spread of MMO5 and GMO5 were determined in 1998. creation of millimeter system MITRIS. It has the same cellular structure, only the hardware is made mainly on domestic equipment, which makes it attractive not only for operators, but also for manufacturers.

Frequency bands between different radio communication services are allocated by the International Telecommunication Union (ITU) at radio communication conferences on the basis of the results of research conducted in ITU member countries presented to the research commissions of the radio communication sector. The main international document that regulates the use of frequencies is the Radio Regulations, which contains a table of distribution of frequency bands between services, as well as separate technical restrictions imposed on the joint use of frequencies by different services. This document specifies the procedures for coordination of systems, as well as the rules for registration of frequencies in the ITU Radiocommunication Bureau.

On the territory of Ukraine, there is a National table of distribution of radio frequency bands between radio services, based on the international Radio Regulations and frequency characteristics of existing local radio facilities. Unfortunately, this table in many respects reflects a somewhat outdated distribution of the radio spectrum inherited from the former USSR. According to it, the entire radio spectrum is divided into special and shared use bands - in contrast, for example, to the National Frequency Allocation Tables

Great Britain, the USA, Germany and other developed countries, where public, special and shared frequency bands are presented in different percentages.

In Ukraine, in the bands of special use of the radio frequency spectrum, the exclusive right to use them belongs exclusively to the relevant structures, and in the frequency bands of shared use, the activity of public radio electronic systems is only permitted. Such inequality in the distribution of frequencies (especially in relation to the public user) and the imperfection of technical norms and standards for the use of the radio spectrum lead to overloading of a number of permitted frequency bands and inhibit the development of national radio means. Thus, the analysis of loading of the permitted frequency bands by radio-electronic means shows (Fig. 4) the clear overloading of a number of frequency bands (2, 4, 8, 11 GHz) and the incomplete loading of others (13 GHz). Obviously, it is necessary to continue the modernization of the distribution of the radio frequency spectrum in the interests of operators providing services to the population.

Currently, in Ukraine, according to the National Table of Radio Frequency Band Allocation and the Radio Communication Regulations, several radio services are defined in the frequency ranges of MITRIS. Basically, the frequency bands occupied by MITRIS are given to broadcasting services, to which MITRIS belongs. However, the range of the MMO5 network is approached by the ranges of mobile means of communication and the noise band of computer radio extenders, and the band of the GMO5 network is assigned to fixed terrestrial and satellite services, which requires a clear frequency separation between them. The frequency range of MITRIS is 11.7-12.5 GHz. This band (according to the Radio Regulations) is also allocated to the following services: fixed, broadcasting, satellite broadcasting and mobile. A significant number of satellite radio broadcasting systems, owned mainly by operators of far-off countries, operate in this range. On the territory

In Ukraine, signals from at least 15 of the most popular television satellites can be received with acceptable quality. The TV broadcasts of these satellites are aimed at the population of their own countries, so the relevant control services of Ukraine do not make it their goal to ensure the immunity of these signals.

At the same time, the Cabinet of Ministers of Ukraine adopted a resolution on the allocation of the 11.7-12.5G77ts frequency band for radio broadcasting, which complements the provisions of the National Table. This opens up new prospects for providing services to the population of Ukraine (in particular, MITRIS).

In connection with the fact that MTRM are ground-based, it is necessary to take into account the provisions when deploying them

Radio communication regulations on joint use of frequency bands with satellite systems. This is due to the fact that when common frequency bands are used together, mutual interference may appear. There is a problem of ensuring electromagnetic compatibility (EMC), i.e. creating such conditions under which the levels of mutual interference do not exceed permissible values and are mutually acceptable. At this time, the most urgent problem is the EMC between different satellite systems, as well as between satellite systems and terrestrial radio lines. This is explained by the presence of a widely developed RRL network, the increase in MTRM broadcast areas and the rapid growth of the number of satellites in geostationary orbit. In order to ensure EMC, a number of restrictions are imposed on various parameters of both satellite and terrestrial radio systems. For satellite broadcasting, one of the main parameters is the power flow density created near the surface of the Earth by the radiated signal. It is determined by the effective isotropic radiated power of the signal from the satellite - the product of the gain of the antenna and the power of the transmitter, and the nature of the distribution of the power spectrum of the radiated signal from the satellite. Thus, it is necessary that in the bands jointly used by the satellite and terrestrial radio relay systems of direct line of sight, the maximum power flux density created on the surface of the Earth by radiation from the satellite, including the radiation from the reflecting satellite, under all conditions and methods of modulation in any band width 4kHz did not exceed the permissible values.

Table 1

The maximum density of the power flow, dB (W/m2), created on the surface of the Earth by radiation from satellites, for different frequencies depending on the angle of arrival of the wave

GHz 2.5-2.659 -152 -152-0.75" -137 3.4-7.75 -152 -152-0.57 -142 8.025-11.7 -150 -150--0.57 -140 12.2-12.75 -148 -148--0.57 -138 17.7-19.7 -115 -115--0.57 -105 x Additional values with the sign "w" - only for the angles of arrival of the wave , close to 5".

Terrestrial radio lines operating in frequency bands shared by satellite service systems and terrestrial line-of-sight radio systems are subject to the following requirements: 1) the power supplied to the antenna input of any terrestrial radio system transmitter should not exceed "1 ZdB(W) for frequencies 1-10GHz and 41OdB(W) for 10-15GHz and higher; 2) the maximum value of the effective isotropic radiating power of any transmitter of such a radio system should not exceed "55dB(W).

With transmitter powers up to 100 mW MTRM of the 12 and 28 GHz bands, where they work together with the satellite radio broadcasting service, the transmitters cannot be sources of interference. In addition, MITRIS, using the 12 GHz band, does not interfere with both satellite and terrestrial radio services.

Thus, the deployment of MITRIS in no way significantly affects the electromagnetic situation in Ukraine.

From the patent literature, the microwave integrated television and radio information system (MITRIS) is known, patent of Ukraine Me30000, cl. НО4В7/165, declared on 12/23/1999, which consists of a subsystem for receiving, forming and processing information, a central station, which in turn contains a multi-channel

NVU - a transmitter with a modulation unit and UHF - outputs of individual channels, a transmission antenna connected to

UHF - a transmitter by a transmission line, subscriber receiving stations, and UHF - the outputs of individual channels of the transmitter are connected to the common output of the transmitting antenna through the straight arms of ferrite circulators connected in series, the transmitting antenna has a circular directional pattern in the horizontal plane and a narrowed width of the directional pattern in the vertical plane, and the microwave transmitter has at least one frequency modulation unit.

The use of this system, according to the authors' idea, allows to increase its information capacity, strengthen the immunity of radio signals; reduce the power radiated by the transmitter to the air and lower the overall power consumption of the system.

The invention is based on the following tasks: - increased range of information transmission; - environmental safety of the system due to the small (up to 50 mW per channel) radiated power to cover a given area when using frequency modulation; - possibility of system operation in duplex mode (reception-transmission); - the use of mass-produced receiving equipment, which ensures maximum reliability and minimum cost (this led to the use of satellite television converters and receivers as the main components of subscriber receiving equipment, as well as the selection of the main transmitted MITRIS signals); - the maximum unification of the element base in order to increase the reliability of the developed equipment and reduce the cost of its production; - modularity of the system (structurally built in such a way that it can be easily expanded both in terms of channel capacity and the number of services provided to the user); - structurally appropriate compactness of the constituent parts to ensure economical transportability and installation on objects without the use of special technological machines and mechanisms, which makes it possible to maximally reduce the time of deploying and collapsing the system; - compatibility with existing cable, fiber optic and telephone networks of information transmission; - compatibility with existing Internet lines, while maintaining the increased information capacity of the system, enhanced immunity to radio and television signals; minimum power emitted by the transmitter into the air, and reduced overall system power consumption.

These problems are solved by the fact that in the microwave integrated television and radio information system (MITRIS), which consists of a subsystem of receiving, forming and processing information, a base station, which in turn contains at least one microwave transmission unit with a frequency modulation unit and microwave output, antenna connected to the microwave transmitter by a transmission line, as well as subscriber receiving stations, according to the invention, single-channel microwave transmission units, at least one for each transmitted channel, based on an active frequency multiplier using its direct multiplication on an avalanche diode, and a device for frequency combining channels of the specified microwave transmission units in the form of a combiner of channel filter combinations with the possibility of maximum weakening of the mutual influence of the specified channel filters and ensuring maximum decoupling between them, make up the transmission trunk of the base station.

At the same time, the system additionally contains equipment for forming a digital channel.

The base station of the system is designed as a transceiver.

The single-channel microwave transmission unit is made with the possibility of one-stage conversion of an intermediate frequency signal of 7O0MHz into a signal of the microwave range, preferably 11.7-12.5GHz, contains a separation board, an amplifier-limiter, an amplifier-corrector, a selective balanced mixer with a standing wave coefficient under voltage (КСХН) of the input is no worse than 1.3, with the possibility of supplying a 16-24 mW signal to the local oscillator input of the local oscillator stabilized by a dielectric resonator, as well as a damping amplifier, a power amplifier and a bandpass filter.

The amplifier-limiter is a three-stage amplifier that provides in the linear mode an amplification of at least 40OdB and an output power level of ZmW when the gain is compressed by IdB.

The amplifier-corrector is a combination of microstrip two-stage corrector ("five-stage amplifier.

The selective balanced mixer contains a low-pass filter (LFF), band-pass filters of the main output frequency signal and a local oscillator, mixing diodes, as well as a microcircuit with microstrip matching and decoupling passive circuits.

The single-channel transmission unit contains a pre-distortion circuit, a voltage-controlled generator, a power amplifier, an active frequency multiplier, with the possibility of feeding a complex video-audio signal to the input of the transmission unit, transferring it to the millimeter range and radiating it using an antenna.

The device for frequency combining channels is made in the form of a diplexer, built on the basis of a circulator, to the two arms of which filters of two channels with different frequencies are attached, and to the remaining one - the antenna flange.

The device for frequency combining of channels is made in the form of combiners for combining channel filters, with the help of which several frequency trunks of transmitters and receivers are connected to one antenna by means of serial addition with the possibility of exceeding, for the channel located further from the antenna, the total losses of the frequency combining path , than for the channel closer to the antenna.

The device for frequency combining channels is made in the form of a segment of a frequency-independent (or frequency-dependent) line of the strip, coaxial or waveguide type.

The device for frequency combining channels is made in the form of a diplexer tee, to the arms of which the antenna is connected, and the receiver and transmitter are connected through bandpass or rejection filters.

The device for frequency combining channels is made in the form of a phase difference device for combining two signals of different frequencies.

The device for frequency unification of channels is made in the form of waveguide bridges connected to each other by two segments of the transmission line of different lengths, and their lengths are selected so that the phase difference at the frequency of one of the composed signals is equal to 0, and at the frequency of the second signal - 1, while transmitters are connected to two inputs of the first bridge, a ballast load is connected to its output, and one of the outputs of the second bridge is connected to the common path.

The device for frequency combining channels is made in the form of a polarization selector, in which both transmitted and received signals have orthogonal polarizations, and consists of two polarization filters, with the possibility of spreading both transmitted signals and signals , which are received, along the general waveguide of round cross-section and the selection of the specified signals through the side arm of rectangular cross-section.

The device for frequency unification of channels is made in the form of series-connected waveguide three-armed ferrite circulators, the arms of which include band-pass filters with previously separated frequencies.

The apparatus for forming a digital channel is made in the form of a video encoder and at least one multiplexer with the possibility of forming a single digital stream from video, audio and service data streams and feeding it to a digital modulator.

The equipment for forming a digital channel is made in the form of functional blocks: a microprocessor system for managing and monitoring the operation of the encoder, a video-audio interface with the possibility of converting analog signals into digital ones, forming a digital stream with a constant transmission rate for a video encoder, as well as forming a constant audio digital stream for an audio encoder, a video encoder of selection information about synchronization from a digital stream and temporary processing of a video signal and its compression, an audio coder for compressing a programmable audio signal, a multiplexer for combining and compressing video and audio symbols, data channels and teletext into a serial transport stream.

The system additionally contains a subsystem of repeaters.

The system additionally contains a subsystem of active and/or passive repeaters.

An active repeater is a maintenance-free radio complex consisting of receiving and transmitting antennas, as well as receiving and transmitting equipment, installed with the possibility of selecting the directional diagram of the transmitting antenna and the level of the output power of the repeater depending on the area of the service area.

The passive repeater is made in the form of an antenna device.

The active repeater without frequency conversion is made in the form of a broadband repeater with amplifiers.

The active repeater without frequency conversion is made with the possibility of retransmitting signals in two polarizations.

The active repeater is made with a frequency shift, with the possibility of decoupling between the receiving and transmitting antennas, in the specified active repeater, the output of the circular waveguide of the antenna irradiator is connected to the polarization selector, with the possibility of separating signals with vertical and horizontal polarization and contains two converters, an adder of intermediate frequencies and an electrically controlled attenuator.

The passive repeater is made in the form of two connected back-to-back antennas.

The passive repeater is made in the form of one or two flat metal mirrors, located to ensure direct radio visibility.

The system additionally contains a subsystem of radio relay stations.

The radio relay station consists of a radio unit for external installation, an antenna with a pivoting device and an access module.

The radio unit performs the functions of a transceiver and is a hermetic container in which the high-frequency modules of the reception and transmission paths are placed.

The antenna with the radio unit with the help of a support-rotating device is made with the possibility of adjustment for vertical and horizontal polarization.

The access module is made with the possibility of providing an interface of the radio relay network with public networks and/or direct subscribers, departmental PBX, mobile communication stations and computer networks.

The base unit of the access module has a connector for connecting cables from the radio unit and the equipment for forming a digital stream, as well as for connecting a technological remote control with a telephone handset, with the possibility of performing the function of a digital modem for communication via a digital stream.

A radio relay station consists of a transceiver and a modem.

The radio relay station is digital and contains a built-in frequency synthesizer.

The radio relay station is made digital and consists of a housing with connectors, internal microwave and digital modules, remote signaling and remote control boards, a power source, while the high-frequency input-output of the transceiver is a standard waveguide flange corresponding to the working range of the station, to the specified flange through a diplexer the input and output of the receiver and transmitter paths, respectively, are connected.

The receiving microwave path of the digital radio relay station contains an input converter, an intermediate frequency selective amplifier, a second conversion mixer and an output amplifier with automatic gain control.

The radio relay station consists of a transmitter, a modem and a receiving part in the form of a receiving radio unit and a demodulator.

The receiving radio unit consists of a waveguide hermetic conductor, a band microwave filter on a dielectric resonator, with the possibility of suppressing side components that arise during signal reception, a low-noise amplifier built in a microstrip design according to a linear three-cascade scheme.

The demodulator includes a demodulator unit, a modem control board, sound boards, and power supplies.

The base station of the system additionally contains an encoder and a computer with the appropriate software for monitoring the collection of subscription fees from users of subscriber reception stations, as well as for protection against unauthorized reception.

The subscriber receiving station of the system contains a receiving or receiving-transmitting antenna, an external receiving module, access equipment and a connecting cable.

The receiver-transmitter of the subscriber receiving station contains a receiving converter of the main range of the system and a transmitter made with the possibility of functioning in another, different from the main range of the system, range and to another antenna.

The receiver-transmitter of the subscriber receiving station is made with one antenna with the possibility of its operation for reception and transmission.

The receiver-transmitter of the subscriber receiving station is made in the form of an integral sub-unit of the HF band containing a mixer and a local oscillator, with the possibility of the mixer operating as a down-converter or as an up-shift mixer depending on whether it is turned on.

The MITRIS system is schematically depicted element by element in the drawings where: Fig. 1 - circular zones corresponding to the operating transmission frequencies; Fig. 2 - diagram of the construction of a four-sector broadcasting zone; Fig. 3 - cellular construction of MRS; Fig. 4 - diagram of loading of permitted frequency bands by radio electronic means; Fig. 5 - nodes included in the transmitter; Fig. 6 - scheme of a selective balance mixer; Fig. 7 - a diagram of a diplexer built on the basis of a circulator; Fig. 8 - complex CHOP schemes using circulators; Fig. 9 - a diagram of a diplexer in the form of a tee; Fig. 10 - a diagram of a diplexer based on a waveguide E-plane tee and five-resonator PPFs with transverse diaphragms; Fig. 11 - amplitude-frequency characteristic of the diplexer according to Fig. 10; Fig. 12 - phase difference device for combining two signals of different frequencies; Fig. 13 - a diagram of a polarization selector with two polarization filters; Fig. 14 - characteristics of the selector switch according to Fig. 13; Fig. 15 - a diagram of an analog transmitter modulator; Fig. 16 is a block diagram of a video encoder; Fig. 17 - block diagram of the multiplexer; Fig. 18 - a structural diagram of the MC MIH module; Fig. 19 - a structural diagram of a multiplexer with redundancy; Fig. 20 - structural diagram of the modem; Fig. 21 - a diagram of a radio modulator for directional stereo transmission; Fig. 22 - diagram of a satellite converter; Fig. 23 - structural diagram of the subscriber terminal converter; Fig. 24 - scheme of a low-power subscriber receiver-transmitter with a small radius of action; Fig. 25 - scheme of the integral sub-block of the microwave range; Fig. 26 - a diagram of a digital tuner of a digital SNTV; Fig. 27 - a structural diagram of a repeater without frequency conversion with transistor amplifiers; Fig. 28 - structural diagrams of active repeaters with the possibility of relaying signals in two polarizations; Fig. 29 - a structural diagram of an active repeater with a frequency shift; Fig. 30 - scheme of the receiving part of the active repeater with one local oscillator; Fig. 31 - scheme of the receiving part of the active repeater with one local oscillator and adder; Fig. 32 - a diagram of placement of radio trunks of one frequency range; Fig. 33 - a scheme with two transformations and the use of a frequency synthesizer; Fig. 34 - a diagram of a television PRS; Fig. 35 - diagram of the receiving radio unit; fig. 36 - the structure of the digital distribution radio relay system.

According to the drawings, the MITRIS system includes a central station (Tse), a set of base stations (BS), active repeaters, subscriber terminals, distribution cable and radio relay lines. CS in MITRIS is designed to receive incoming information that is subject to further distribution and processing (if necessary), to form and broadcast a packet of information signals. The station includes: the MITRIS receiver-transmitter, which contains a microwave transceiver module with modulators and demodulators, an antenna system, a satellite television reception complex - a teleport, distribution radio relay lines (RRL) and fiber-optic communication lines (VOL3Z), equipment reception of data from the Internet using Oigesi RS technology, equipment for communication with TV and radio studios, power supply complex.

Signals of satellite TV and radio programs are received by the teleporter and fed at the level of video and audio signals to the inputs of the modulators of the corresponding channels of the transmitter. Similarly, the inputs of the corresponding modulators receive signals from RRL or VOLZ, from TV studios and public telephone networks. In the transmitter, the signals are modulated, converted in terms of frequencies and levels, amplified, collected into a group signal and radiated into the ether through the antenna. Subscribers' access to information is controlled by the subscriber coding and accounting system. The power supply complex is designed to ensure uninterrupted power supply of station equipment in various situations. Digital and analog channels are broadcast at different frequencies and have independent channel-forming equipment of the modem part.

Transmitter MITRIS. The BS MITRIS transmission trunk is intended for the formation of a "trunk" packet of information signals. It consists of single-channel microwave transmission units, at least one for each transmitted channel, made on the basis of an active frequency multiplier using its direct multiplication on an avalanche diode, and a device for frequency combining the channels of the specified microwave transmission units, made in the form of unifiers of combinations of channel filters with the possibility of maximum weakening of the mutual influence of the specified channel filters and ensuring maximum decoupling between them. Signals from the output of each transmission unit are sent to the device of frequency combining of channels, from the output of which the "trunk" packet of signals is removed.

The single-channel transmitter carries out a single-stage conversion of the IF signal of 7O0 MHz into a signal of the high-frequency range (11.7-12.5 GHz). Nodes included in the transmitter are shown in Fig.5.

In the transmitter, the input signal with a frequency of 7ΩMHz (at the level of 0.017-0.58) together with the supply voltage "248" from the external modulator through the coaxial connector Input enters the separation board. The board emits an informational signal (7OMGiu) and enters the limiting amplifier, which maintains a constant signal level of the order of 200μW at its output, and -24V8 voltage is supplied to the power board.

The amplifier-limiter is a hybrid integrated three-stage amplifier on a transistor assembly and provides in the linear mode an amplification of at least 40dB and an output power level of ZmW when the KP is compressed to TdbB.

Then the signal enters the amplifier-corrector, which is a combination of microstrip two-stage corrector and five-stage amplifier. Here the signal is amplified, and its characteristics of the group delay time are corrected. KSHN output is not worse than 1.25.

Next, a signal with a frequency of 70 MHz and a power of 2-2.5 mW is fed to the input of a selective balanced mixer (the KSHN of the input is no worse than 1.3), the local oscillator input of which is supplied with a microwave signal with a power of 16-24 mW from the output of a transistor local oscillator stabilized by a dielectric resonator (DR) .

The electrical diagram of this mixer is shown in Fig.b. It includes a low-pass filter (LFF), band-pass filters of the main output frequency of the PPF signal! and local oscillator PPF2, mixing diodes and a microcircuit with microstrip matching and decoupling passive circuits sprayed on it. The low-pass filter is made on concentrated elements and is designed to suppress the spectral components of the modulated intermediate frequency signal, which could fall into the PPF passband of the output signal due to nonlinear transformations on the mixing diodes. The low voltage filter also prevents hitting

microwave power in the IF path. The local oscillator frequency bandpass filter PIPF2 provides suppression of the spectral components of the higher harmonics of the local oscillator signal, and the PPFI filter suppresses to an acceptable level (not less than 5OdB) all the main, non-spectral components of the output signal of the mixer, which is received and isolates only the frequency of the main channel at its output . When using mixing diodes and, as a PPF, filters on four dielectric resonators (DR) with an inherent Q factor of 5000, the characteristics of the mixer are as follows:

Input frequency, MHz 70

Through working lane, MHC 28

Range of selected frequencies, literal execution, GHz 11.7. 15.5

Conversion losses, dB 6-7

Local oscillator signal power, mW 16-24

Maximum output power, mW 50

Suppression of the local oscillator signal at the output, dB, not less than 50

Mirror signal suppression, dB, at least 50

The signal with a power of 200-300 μW obtained in this way is fed to a damping two-stage monolithic amplifier, from the output of which the signal, amplified to the level of maintaining the necessary effective mode of operation of the power amplifier (45 mW), is transmitted to the latter. The power amplifier has a KP of at least 20dB, and the harmonic filter installed at its output ensures the suppression of harmonic components at least bOdB. To control the operation of the power amplifier, a detector is located in it, which emits a control signal of 0.8-18 to the contact of the 24-pin Control connector. Contacts 71 and Z of this connector are used to control supply voltages 9 and 4128. From the output of the power amplifier, a signal with a power of 200-300 mW enters the PPF on the DR. After the PPF, a signal with a power of more than 100 mW is sent to the output of the block through a sealed input. The output filter provides decoupling by more than 2OdB at frequencies detuned from the central one by 32MHz, and by more than 12dB at frequencies detuned to 520MHz, which makes it relatively easy to organize the operation of several transmitters on one antenna.

The MITRIS transmitter provides the following technical characteristics:

Power level, mW at the input of the block 0.006-4 at the output of the block, not less than 100

The level of side emissions, dB, is not more than -70

Local oscillator frequency instability, 17/...7 8-10

KSHN, no more: at the entrance of the block 11 at the exit of the block 1.25

Irregularity of the group delay time (HG3), no more than 5

Consumed power, no more than 12

Weight of single-channel unit, kg 11

The peculiarity of the transmitters of the microwave range is the difficulty of obtaining high power levels, which led to their construction, mainly according to a single-channel scheme. Moreover, in the I MO5 and MMO5 networks, each channel transmitter has its own horn antenna and forms a completely independent node.

The configuration of the transmission barrel MTRM of the HF range is similar to the construction of the transmitter in radio relay systems. The information signal after the modulator on a standard IF 70 MHz is supplied via a coaxial cable to an external transmission module with an antenna. The latter converts it up into the working range of XMTRM (28 or 42GHz) and amplifies it to the required power level.

Table 2

Technical characteristics of active frequency multipliers based on LED signal, GHz mW (in the 190 band) signal multiplication, mW 22-23.5 15-80 3-4 150-400 26-37.5 15-80 5-8 150-600 36 -53.5 15-80 6-10 150-600 53-65.5 15-60 8-11 200-600 65-78.5 15-30 9-12 200-600 78-100 5-20 12-16 300-800 100-118.5 5-15 15-19 300-800 118.5-150 5-10 19-25 400-1000

Notes: 1. The relative level of side harmonics is no more than -40dB. 2. The spectral density of the AM input power and FM noise in the 1 kHz band is no more than 120 dB/Hz.

The basis of the MITRIS transmitter is an active frequency multiplier that uses direct frequency multiplication on an avalanche diode with high efficiency at large multiplication factors. This makes it possible to transfer a coherent signal almost without distorting its spectrum from the centimeter range to the millimeter range. Thus, the problem of obtaining a high value of frequency stability in the microwave range is also solved.

The principle of operation of another MITRIS transmitter is that a complex video-audio signal is fed to the input, which, through the pre-distortion circuit, is fed to the voltage-controlled generator (VCG); from the output of the generator, a signal with a power of about 50 mW in the range of 5-6 GHz is fed to the power amplifier, which accelerates it to 400 mW, after which the amplified signal enters the active frequency multiplier, is transferred to the millimeter range and radiated using the antenna. To stabilize the frequency of the master generator within the necessary limits, it is placed in a thermostat, in which a constant temperature (-4052)"7С is maintained with the help of a control circuit.

Technical characteristics of the MITRIS transmitter:

Output power, mW, at least 60-75

Instability of the output frequency in the operating temperature range,

MHC, no more than 2.5

Suppression of side emissions, dB, not less than 50

Range of output frequencies, GHz 27.5-29.5

Operating temperature range, "С -40...-60

Multi-channel frequency combining devices. In the transmitters and transceivers of the MITRIS system, frequency combining devices are used, which serve to summarize (combine) the narrowband signals of individual single-channel transmitters into one common broadband and separate the receiving channels from the transmitting ones. The interest in these devices is mainly due to the desire to eliminate the contradiction between the increase in the flow of information (the increase in the number of transmission channels) that must be transmitted and the limited frequency range in which MTRM transmission equipment works. This discrepancy leads to the fact that the guard interval between adjacent channels is significantly reduced. If previously the ratio between the bandwidth of a separate channel and the bandwidth of the protective interval was 2 units. and more, now - 1-1.50 units. In essence, the problem of designing a PNP is reduced to finding a compromise between the losses in each communication channel and the amount of frequency resolution between adjacent channels of the system.

The losses in the frequency channels and the resolution between them depend not only on the actual channel filters, but also on the device that combines the channel filters into a single system. In a properly designed radio system, the unification device introduces minimal losses in the passband of channel filters, makes it possible to obtain the necessary resolution between channels and eliminate the mutual influence (misalignment) of channel filters.

In this regard, the selection of elements and nodes is of primary importance in frequency coupling devices.

In the microwave and microwave bands, frequency-separating filters are built on the basis of directional filters, PPF and hybrid connections, narrow-band blocking filters, etc. Any n-channel PNP is a set of n-channel, for example, bandpass filters, assembled into a single device using a special combiner (or separator). Channel filters can be based on: waveguides with diaphragms or pins; counter-rod structure; coaxial resonators, including those with dielectric filling; of non-boundary waveguide-dielectric structures.

The type of filter is mainly determined by the frequency range and the specified technical requirements. In any case, the filters should give minimal losses in the passband at a given steepness of the amplitude characteristic.

All the variety of channel filter connectors can be conditionally divided into two groups: 1) connectors (or disconnectors), which allow to maximally weaken the mutual influence of channel filters and increase the separation between them; 2) connectors that serve only to connect channel filters. The first group includes hybrid connectors and ferrite decoupling devices. Hybrid connections, when using matched loads with a KSHN close to 1.5, provide a separation between channels of 25-40dB, however, additional losses for each communication channel amount to ZdB. As hybrid connections, directional and loop branches are used on ZdB, slotted hybrid branches and connectors of the "magic T" type. In the case of using a multi-arm circulator of the "surface wave" type, the additional decoupling between the arms reaches ЗОdBb, but for the number of channels more than 8, the losses become very large (-4dB) (-0.5dB per one arm) and the difficulties in implementing magnetic systems.

At the same time, the main advantages of frequency combining devices built on the basis of such connections are almost complete independence of setting channel filters. The adjustment of each subsequent filter does not affect the matching of the filters of the previous channels, which allows to obtain a high degree of matching in the bandwidths for a large number of channels. This circumstance is of fundamental importance for MTRM, where operational access to each single-channel transmitter is required.

It should be noted that usually such CHOPs are built according to the sequential scheme of frequency channel selection.

The main disadvantages of sequential selection schemes are the bulky design and large additional losses.

As a unifier of the first group, a diplexer (Fig. 7) is used, built according to a standard scheme based on a circulator, to the two arms of which filters of two channels with different frequencies are attached, and to the remaining one - the antenna flange.

With the use of circulators, it is possible to create quite complex PNP circuits, with the help of which dozens of frequency trunks of transmitters and receivers can be connected to one antenna (Fig. 8). At the same time, due to the sequential construction for the channel located further from the antenna, the total losses of the CHOP path will be greater than in the channel located closer to the antenna.

The connectors of the second group are, as a rule, a segment of a frequency-independent (or frequency-dependent) line of the strip, coaxial or waveguide type. In this case, channel strip filters are connected to the dividing line through segments of transmission lines of a certain length and at a certain distance from each other. For example, waveguide tees in the H- or y-plane are used as a separator for a waveguide-type PNP. Such CHOPs are usually built according to the parallel scheme of frequency selection. The losses in them are mainly determined by the losses introduced by channel filters, and the decoupling between channels is determined by the steepness of the frequency response of these filters.

The advantage of CHOP with a parallel frequency selection scheme is that they effectively combine the work of receivers and transmitters on one antenna. This type of SPD is advisable to use when there is a large frequency difference of neighboring channels compared to SPDs on ferrite and hybrid elements. A significant drawback of such systems is the mutual influence of channel filters, which greatly complicates their reproduction and adjustment.

An example of the second type of CHOP can be the design of a diplexer in the form of a tee (Fig. 9), to the arms of which the antenna is connected and through the appropriate bandpass or rejection filters - the receiver and the transmitter.

The length of the shoulder is selected so that the transmitter signal enters the antenna without reflections. The length of the 1-g arm ensures the reception of the received signal without reflections in the receiver.

In the development of this design for the microwave range, a diplexer (Fig. 10) was created on the basis of a waveguide E-plane tee and five-resonator PPF with transverse diaphragms 1 with a thickness of 0.5 mm and a cross section varying from 1.55x1.2 mm to 4.16x3 ,4mm, and 2 resonators based on segments of a rectangular waveguide.

The input-output flanges of the diplexer are made for a waveguide with a cross-section of 7.2x3.4mm. Its dimensions are 90x30x24mm. The amplitude-frequency characteristic of the diplexer is shown in Fig. 11. At the КСХН at the input of the tee no more than 1.2, on the input-output arms of the diplexer in the passing bands the КСХН does not exceed 1.45. Passage losses in both arms are no more than 1.5dB.

For frequency compression of waveguide tracts with signals from one or more powerful transmitters, resonator-less circuits for composing signals of different frequencies are used. These circuits have high electrical strength, low losses, low distortion of phase characteristics, and high matching with the waveguide path and transmitter outputs.

A phase difference device for combining two signals of different frequencies, shown in Fig. 12. It consists of two waveguide bridges 1, connected to each other by two segments of LP of different lengths.

Their lengths are selected in such a way that the phase difference at the frequency of one of the two signals being composed is equal to 0, and at the frequency of the second signal - l. Transmitters are connected to the two inputs of the first bridge. One of the exits of the second bridge is connected to the general tract. Ballast load 2 is connected to its other output. One of the properties of the bridge is that the signals at frequencies ii and 2, which arrive at different inputs of the bridge, are divided between its outputs into two levels by the amplitude of the component. At the same time, if the phase shift between the components of the signal received from one of the inputs is equal to F, then the phase shift between the components of the signal received from the second input at the same points is Phil. This phase shift is compensated by the phase shift, which is obtained due to the different lengths of the LP segments connecting the two bridges. Thus, at the inputs of the second bridge, the phase ratio of the components of both signals is the same, and they both go to the same arm of the bridge, to which the common waveguide path is connected. However, the different lengths of LPs connecting both bridges provide a phase shift equal to l only at the average frequencies of the composed signals. When deviating from these frequencies, the phase shift becomes different from l, therefore, within the limits of the working bands, part of the power of the composed signals enters the ballast load.

A universal diplexer, used starting from the range of decimeter waves, is a polarization selector where the received and transmitted signals have orthogonal polarizations. Polarizing filters are used to combine these signals. Fig. 13 shows the polarization selector, which consists of two polarization filters, where both the transmitted and received signals are propagated along a common waveguide of round cross-section with a diameter of 8 mm and are separated through a side shoulder of a rectangular cross-section of 7.2 x 3.4 mm. The orthogonality of the reception and transmission signals is determined by the mutual perpendicularity of the E- and H-planes of the corresponding rectangular waveguides. Such a polarization selector ensures in the working band the transient attenuation between the reception and transmission paths is more than З37dB, and the loss on the passage in both arms is not more than 0.ZdB. Characteristic

The KOSKHN of the selector is shown in Fig. 14.

Multi-channel (up to 24 trunks) MITRIS frequency combiners are built according to a sequential frequency selection scheme using narrowband PPFs on miniature DRs in the frequency ranges of 11.7-12.5GHz and 27.5-29.5GHz. The conducted studies confirmed the possibility of creating similar devices in the frequency range up to 5 GHz. The use in the microwave range of miniature DRs, comparable in quality to waveguide resonators, but having much smaller dimensions, not only significantly reduces the mass, dimensions, metal content and cost of the CHOP, but also increases their resistance to the influence of destabilizing factors in a wide temperature range from -607 up to "85" C. The value of the intrinsic Q factor of the DR depends on losses in the dielectric and losses on radiation (which is essentially eliminated by shielding).

The basis of the CHOP are narrow-band PPFs for five to seven DRs made of ceramics, which have the following technical characteristics:

Bandwidth by level -

O,ZdB from the level of minimum losses, MHz 2412

Operating frequency range, GHz 11-14

Attenuation when detuning from the central frequency at 128MHz, dB, not less than 35

Losses in the transmission band, dB, no more than 3-4

Entry and exit KSHN, no more than 12

Center frequency deviation in the operating temperature range, MHz, no more than 0.5

Average working time per failure, hours, at least 100,000

Input and output waveguide section, mm 19x9.5

The filter housing is Hermetic

In order to eliminate the influence of the CHOP channel filters on each other, waveguide (cross section 19x9.5mm) three-armed ferrite circulators are used, connected in series with each other, in the arms of which PPFs with pre-spaced frequencies are included. Circulators have the following basic technical characteristics:

Losses of each arm, dB:

Direct 0.05-0.1

Reverse 30-35...

Decoupling between any of the shoulders, dB, not less than Ko)

KOHN of each shoulder (within) 115

Modem and channel-forming part. Analog modulator. An analog modulator used for MITRIS transmitters is considered. Its purpose is to form the information structure of the signal transmitted by BS MITRIS on the IF. The functional scheme and composition of the modulator are shown in Fig. 15.

When the modulator is working, the full color television video signal is fed to the matched attenuator of the Ai7 video unit and through the switch to the standard pre-distortion circuit, which weakens the low-frequency components of the video signal. The frequency response of the circuit is standardized and corresponds to the renewal circuit of the standard satellite tuner, which is part of the receiving subscriber equipment

MITRIS. Lowering the level of low-frequency components of the video signal is necessary to reduce transient interference from the video signal to the channels of sound accompaniment and sound broadcasting, organized on the corresponding subcarriers. Next, the video signal is fed to a low-pass filter (LFF) with a cut-off frequency of 6 MHz, a video amplifier and a phase corrector, which eliminates the unevenness of the group delay time characteristic

FNU in the band up to 6 MHz. The attenuation of the replacement attenuator is ZdB, which corresponds to the attenuation introduced by the pre-distortion circuit at the "zero" pre-distortion frequency of 1.5 MHz and is used in technological measurements of the modulator parameters. From the output of the phase corrector through the switch, the video signal enters the IF unit A2 on one of the inputs of the adder, the second input of which receives the total signal of various subcarriers, frequency modulated by various audio signals.

The generated group signal (GS) from the output of the adder is fed to an amplifier with a frequency response linear in the frequency band from 0 to 20 MHz, then it is limited by a low-pass filter and fed to a frequency-modulated varicap generator with a frequency of 7 MHz. The modulation characteristic of the generator has a high degree of linearity in the frequency range of 704-12MHz. At the nominal value of the amplitude of the video signal on the video input modulator connector 1-50,058, the IF signal deviation is 16.0:0.24MHz. At the same time, the unevenness of the differential modulation characteristic of the measurement on the PU Output 1, PU Output 2 connectors is no more than 295. To eliminate the higher harmonics of this signal, a low-pass filter with a cut-off frequency of 100 MHz is used. The unevenness of the characteristic of the group delay time of the entire IF path is regulated by the phase corrector and is no more than 2ms. The signal comes to the connectors Output PU 1, Output IF 2 of the modulator through an amplifier with two independent outputs. Its amplitude on these connectors is 500150 mV. The non-uniformity of the frequency response of the entire IF path in the frequency band of 702412 MHz does not exceed 0.5 dB.

The AZ sound block is designed to form a set of frequency-modulated by various sound signals carrier signals of sound accompaniment or sound broadcasting. Structurally, one block is formed from two sound subcarriers, but a larger number of sound subcarriers may be required. Then the modulator is equipped with two or three sound blocks. When the device is working, two sound signals are sent to the Sound Input 1 and Sound Input 2 connectors via symmetrical three-wire lines (two wires for anti-phase signals and a common wire - the screen), which is necessary to reduce interference and background interference, as well as to match the studio equipment Next, the signals are sent to matching circuits that convert symmetrical lines into asymmetrical ones, and then to standard pre-distortion circuits with a time constant of 5 Ohms. These circuits improve the signal-to-noise ratio in the sound path on the bdB. During measurements, or in case of other necessity, for example, if there is no regenerative circuit in the receiver, the pre-distortions can be turned off by the control signal from the control and display unit A4. From the predistortion circuit, the signals are fed to the low-frequency amplifier and low-pass filter. Then they are fed to the corresponding FM generators of carrier signals with frequencies и and и2, respectively. The value of the frequencies of the carrier signals is maintained with an accuracy of no worse than 10kHz using parametric stabilization or a system of phase auto-adjustment of the frequency. The value of the frequency of the subcarrier signals is selected in the range from 6.5 to 8.25MHz and can be any of 7000, 7360, 7765, 8215, 8710kHz. The signals of these generators through the Subcarrier 1 and Subcarrier 2 switches are sent to the input of the adder, and then to the high-pass filter (HFU).

This filter prevents differential frequency signals of audio subcarriers, which arise as a result of the nonlinearity of the adder, from entering the spectrum of the video signal. From the high-frequency output, the total signal of the sound subcarriers enters the input of the adder of block A2.

When transmitting audio programs in digital form, six audio signals are converted into a digital stream with a speed of 2048 Kbit/s, which modulates a carrier signal with a frequency of 7765 kHz.

The A4 control and display unit is intended for signaling the operability of the modulator devices, namely, being within the specified limits of the sound subcarrier signal level (Subcarrier 1 indicators,

Subcarrier 2) and IF (IF indicator). Indicators Video, Sound 1, Sound 2, HS signal the presence of corresponding signals at the inputs of the modulator.

The presence of the HS input connector of the IF unit allows this modulator to be used for transmitting, in addition to television, any other signals in the frequency band up to 20 MHz. Through this input, you can send digital telephony signals with a flow rate of up to 8 Mbit/s or communicate in computer networks complying with the 10Vase-Tt standard at a speed of up to 10 Mbit/s.

The A5 power supply unit provides stabilized voltages of 12 and 12 volts to the modulator device and an unstabilized voltage of 1248 to the transmission microwave unit. At the same time, the transmission unit receives power through the central conductor of the coaxial cable, which supplies the output signal of the modulator, through the decoupling circuit from the choke and the capacitor. The transmission unit has its own stabilized sources of secondary power supply.

Digital channel formation equipment. Currently, the transport flow of the MPRES-2 standard is used to form digital channels in the transmitters of the MITRIS system. In this regard, the first node in such a digital channel is a video encoder that forms a single digital stream from video, audio and service data streams. A number of these streams with the help of multiplexers are combined into one, which is fed to a digital modulator.

A real-time video encoder is proposed. It is intended for the formation of a single transport stream of the MPRES-2 standard from differential and composite video signals, an analog sound channel, digital video and audio streams (270 Mbit/s), teletext and data stream (up to 2 Mbit/s). Fig. 16 shows a block diagram of a video encoder consisting of the following functional blocks: a microprocessor system for managing and monitoring the operation of the encoder; a video-audio interface that receives analog and digital signals from various sources, converts analog signals into digital ones, forms a digital stream with a constant transmission rate for the video encoder, and also a constant audio digital stream for the audio encoder; the actual video encoder, which extracts synchronization information from the digital stream and performs temporal processing of the video signal and compresses it; an audio encoder that compresses the audio signal; programmable multiplexer, which combines and compresses video and audio symbols, data channels and teletext into a serial transport stream. The technical data of the input serial interfaces of the coder are given in the table. 3.

Table C

Technical characteristics of the input serial interfaces of the encoder vetal digital 5OI (Zepa! | vms, 750Mm, unbalanced 270-108 ideas!

Low-speed data K5-422 9-rip O-z-ure melts 2;4:4,8;:9,6; 19.2 and 38.4

High-speed data K5-422 15-rip O-iure taye 2-103 "Rec. 656-1 MSE-R.

Technical data of the encoder's video and audio input interfaces are given in Table 4.

Table 4

Technical characteristics of video and sound input interfaces of the Mideo television signal encoder (Sotroviite VMS, 75Ωm, unbalanced Mtes-M xU-S Mideo 5-UN5 4-pin Mipi-OIM, 0.75Ω, unbalanced |(525/60 lines/Hz),

X-0-M Mideo Veiasat-OR ВМсСхХЗ3.75Ω, unbalanced RA -B (625/50 lines/Gu);

Navy teletext, 75Ω, unbalanced 25Hz-5.75MHz

Digital sound H5-422 (1-4 channels) Z-rip Х.К., Tetaie, 110Ω, balanced

Analog sound (1-4 channel 600Ω, balanced "Rec. 624-1 MSE-R.

Technical data of the output interfaces of the encoder are given in Table 5.

Table 5

Technical characteristics of the output interfaces of the coder - I Effective transfer rate | Physical linear rate,

Yan ОЙ автиятяеня! 3

TTL, balanced. 1,536; 2,048; 3,072; 4,096; 6,144; infusion

External 1.5-8.448 led me t

OMV ABI 8,192 and 12,288 270

External 1.5-8.448

To combine streams received from the encoder of the MPEC-2 standard, you can use a multiplexer designed to combine up to 15 streams from different sources into one digital transport stream and includes the following modules (Fig. 17): SRO, which is a microprocessor a system that controls the operation of the multiplexer and provides a local user interface to the computer; MS MIKH - multi-channel multiplexer serving up to eight transport streams (two MC MIKH can be installed);

ZMOA - a module forming an interface to a computer monitor of the ZMOA type; ESHPegpay - interfaces for connecting to the MM5 network management system and additional CA access (Sopayiopay! Assez5); power module; hard disk for storing management software; MS BMI is a module that provides an interface with MS MIC for various non-standard input streams, as well as an output interface for scrambled streams.

The input interface of the multiplexer has the following technical characteristics:

Number of entries:

Basic 8

Additional 7

Data transfer rate (effective), Mbit/s: basic interface K5-422 2-15 additional interfaces

THESE; OMV/ABI Noah ipktm; RagaiIei rmuv-im up to 38 a.703 34,368

The following interfaces are used as output interfaces: Ragaye and Yumv; K5-422/5epya!I! IMO5; YMV/ABI NoShshipktm; THESE; b.703, which provide an effective data transfer rate of up to 40 Mbit/s (additionally up to 55 Mbit/s).

The serial interface of the built-in SRO type KS-323 has two inputs. IEEE 802.3 IEEE 10Vase-t and IEEE 802.3 IEEE 10Vase-2 interface standards in this multiplexer. The average power consumed by the multiplexer is 200W, the peak load is 300W. Its weight is 15 kg, overall dimensions are 17.3 x 50 x 483 cm.

The structural diagram of the MS MIC module is shown in Fig. 18. Eight separate program transport streams arriving at its inputs are processed by the appropriate number of input chains, which consist of the following blocks: 1) a serial input interface that provides access to the digital stream to the MS MIC module; 2) a logic circuit that checks the veracity of input data and generates the corresponding indication signal; regulation of the redundancy of the input stream and the formation of a 188-byte data stream; conversion of serial data into parallel format; 3) RIO (Horn of Ypres - Horn of Oshiria: first in - first out) - a module that performs flow buffering functions; 4) a digital signal processor (DSP), which is the central element of the MIH MC and provides: reception of the incoming traffic stream and extraction of packets from it containing cells with service or program-specific information (then this information is sent to the SRU module for analysis); inserting the information received from the SRO module into the output transport stream; multiplexing of all incoming streams into one; 5) output RIO, where the transport stream is buffered after the digital signal processor (DSP). The output of the MS MIC has three different interfaces: TACHI; ОМВ/А5БИ Noiipkti; Ragaiyei OMV.

When forming digital channels for the transport flow of MRES-2, modulators YOMV 3000/3030 manufactured by "Kadupe Sogrogaiiyop" and 1715-5032 8-M5V manufactured by "AOS IT5" can be used

Sogrogayop", USA.

Digital video transmission modulator OMV 3000/3030 is fully compatible with ET5 (Esgoreap TeIesot 5iapadaga), OMV and MPRES-2 standards, and its technical characteristics are as follows:

Output frequency range: main, MHz 50-90 additional, MHz 100-180 grid step, kHz 2.5 stability 1b0rrt

Output signal level: power, dB(mW) -5...-25 step size, dB 0.1 accuracy, dB 0.5 stability, dB 0.5

Output impedance, Ohm:

main 75 additional 50

Return loss, dB 20

Phase noise level, dB/Hz, when detuning from the carrier: 100Hz 63 1kHz -73 1oKkHz 83 10oKHz -93

Connector type VMS, Retaije

Modulation type:

Additional 8 YEARS of the main ORBK

Spectral mask Reg ET5 300-421

Variable data transfer rate, Mbit/s: in narrow band 1-16 in wide band 1-50 step size 1

Symbol speed, symbols per second: in the narrow band 10x106 in the wide band ЗОх106

Optimal fixed data transfer rate, 50 Mbit/s

Direct error correction (DEC): SopuoiIshiop's internal code! K-7, (171,133) speed 1/2, 2/3, 3/4, 5/6, 7/8 external Reed-Solomon code (204188, T-8)

Data scrambling Reg ET5 300-421

Data interface: serial ("16 Mbit/s) v5-422/449, (1.703 (NOVU) OMV AB - "NoitspK"" parallel (5 50 MbNT/s) v5-422,25-Rip'i, OMV, ! 5-422,25-Rip'U, Oiyegepiai/ECI "

Stability of the internal synchronization generator 1Oorrt

Control interface"" (serial) -85-485, .A5-232, EIPegpei, 10Vase-i"

Power supply: power, V-A 100-240 frequency, Hz 50-60... current. And 0.5

The range of working temperatures, "С 0 - -50

Humidity, 956, no more than 95

Mass, kg 4

Dimensions, inch 19UU x 170 x 1.755 x Extra. "x Monitored parameters: output frequency, output signal level, output signal on-off, data rate, symbol rate, data polarity, internal code rate, operation mode test.

The modulator is designed to process signals in MPRES-2 format. MPRES-2 package can contain audio, video signals, data arrays. Test signals are displayed on the liquid crystal display of the front panel.

The interface with the K5-232 port provides, if necessary, communication with a personal computer for controlling parameters and switching modes. The main parameters of the modulator:

Modulation type 8- M5V

Signal-to-noise ratio, dB 32 36

Data transfer rate, Mbit/s, per channel with a width of 6 MHz 19.28

Output frequency, MHz AA

Output impedance, Ohm 50

Output signal level, dB(mV) 20...10

Power consumption, W 50

In the case of working with digital streams of the c5.703 standard, it is necessary to use the appropriate equipment designed for the transmission of a number of asynchronous digital streams in the RRL trunk. It is used to organize connecting lines between PBXs, between communication nodes and ground stations of satellite communication, etc.

The equipment receives and asynchronously combines digital streams of 2048 Kbit/s each into a group stream of 34368 Kbit/s, modulation and demodulation of the IF signal, asynchronous separation of 2048 Kbit/s streams, redundancy, control of the error rate without interruption of communication, as well as service communication connection The joint parameters correspond to the standard .703. At the same time, the ATC provides the following technical parameters:

IF modulation Quasi-ternary frequency

The frequency spectrum of the IF signal, 70-14 engaged in level -

ZOdB, MHz

The level of the modulated IF at the output on a load of 75Ωm, mV, not less than 5Obef.

The permissible range of change in the input level of the IF, in which the operability of the equipment is preserved, mV, is not less than 75-30bef.

Output and input resistance" with attenuation of mismatch not less than 28dB in the frequency band 60-8ΩHz, Ohm 75

Irregularity in the (702412) MHz band, no more than:

frequency response dB 1

GVZ, not 18

Characteristic asymmetry

GVZ at frequencies (70210 MHz, no more than 8 "The supports at the input and output of IF signals are asymmetrical.

The set of equipment consists of constructively finished blocks: a multiplexer and a modem.

The multiplexer is designed to transmit sixteen asynchronous digital streams at a speed of 2048Kbit/s in a group stream at a speed of 34368Kbit/s. Interfaces of the joint correspond to the standard (p. 703.

The NOV-3 code is used for the transmission of incoming and outgoing streams. Flow inputs and outputs can be symmetrical or asymmetrical.

Let's consider in more detail the device and operation of the multiplexer with redundancy, the structural diagram of which is shown in Fig. 19. Sixteen information streams in the NOV-3 format from the connector Inputs 2048 NOV-Z (116) are sent to the multiplexer unit, which combines them into a group stream. The multiplexer block inserts cyclic synchronization signals of the receiving equipment with a frequency of 8015 Hz into the received stream.

In addition, it forms sixteen service streams with a speed of 32.06 Kbit/s, which transmit service phone signals and information about the state of the equipment. These signals are also inserted into the group stream.

Six service streams can be used to transfer user information. The resulting flow is fed to two independent connectors 7 and 2. Outputs 34368 NOV-3 (the second connector is spare) for transmission via a communication channel or modem. The demultiplexer accepts two streams with a speed of 34368 Kbit/s in the NOV-3 format from the connector Inputs 34368 NOV-3 (1 and 2), converts them into binary, selects the one containing fewer errors from the two streams, synchronizes it and divides it into sixteen streams with a speed of 2048Kbit/s, converts them into a quasi-ternary form of NOV-3 and sends them to the connector Outputs 2048 NOV-3 (1-16). If there is no signal on the transmission side at the input of the flow, an emergency signal is generated at the corresponding output. If reception is not possible (communication channel is broken), the emergency signal is sent to all Outputs 2048 NOV-3.

In addition, the demultiplexer allocates sixteen service streams with a speed of 32.06 Kbit/s, which transmit service phone signals and information about the state of the equipment. Information flows on

Inputs 34368 NOV-3 (1 and 2) should arrive simultaneously if possible, that is, the difference during the passage of the signal from the source to the connector Inputs 34368 NOV-3 should be minimal (no more than 480ne).

The service communication block (BSZ) is intended for the organization of the service communication channel between the multiplexer blocks using the delta modulation method. It converts the speech signal from the handset microphone into a 32.06Kbit/s stream and feeds it to the multiplexer unit for transmission to the other end in one of sixteen service streams. The stream received from the other end of the line by the demultiplexer unit is converted into a sound signal.

The control unit (BC) measures the error rate in the path based on the error signals in the sync word received and received from the demultiplexer unit. In addition, BC has a test signal generator - a pseudorandom sequence (PSS), the structure of which corresponds to that described in Ric. MKKTT 0.151. The output signal of the PVP generator in the NOV-3 format is sent to the PVP Output connector and to one of the inputs of the switch K. From the PVP Output connector, the signal can be fed to any of the sixteen connectors Inputs 2048 NOV-3, for measurement error indicators. The PVP signal received at the other end of the line from the corresponding Outputs 2048 NOV-3 connector can be fed to the Input connector of the PSP. BC counts errors in this signal, and in the absence of a signal on the connector - in the sixteenth stream. BC also collects and displays information about the status of the MH-34-16/2 multiplexer and incoming streams through a liquid crystal indicator.

The switch (K) provides selection of the signal coming to the input of the sixteenth stream. The reference generator G34368 produces a clock sequence with a frequency of 34368kHz, which is necessary for the operation of the multiplexer. The G32772 Pd and G32772 Pm generators produce clock sequences with a frequency of 32772kHz, which are necessary, respectively, for extracting 2048kHz clocks from their input streams and for restoring 2048kHz clocks to form output streams. The power supply unit of the PSU produces voltages "5 and -58" necessary for powering the units of the MH-34-16/2 multiplexer. Electricity is supplied from a source of direct current with a voltage of 20-29 V or 54-72 V. The consumed power is no more than 100W.

The modem provides transmission and reception of one quasi-ternary stream in the NOV-Z code at a speed of 34368 Kbit/s. The flow is transmitted through the duplex barrel of the RRL equipment by forming a modulated one

IF 7О0МХЦц. The structural diagram of the modem is shown in Fig.20. During transmission, the incoming quasi-ternary stream with a speed of 34368 Kbit/s is fed to the NOV-3 Input connector of the NOV-3 Codec block. This block decodes and converts the input signal into a unipolar digital stream 034, forming a clock sequence 734 corresponding to its speed. Scrambling of the digital stream and frequency modulation of the 7MHz carrier frequency are performed here.

At reception, the output of the IF path of the PRS transceiver is connected to the IF input connector of the frequency demodulator node. The node carries out frequency demodulation of the received signal, formation of a digital unipolar stream with a speed of 34368Kbit/s, generation of clocks with a frequency of 34368kHz, and in the absence of an IF input signal, the formation of emergency signals "Accident" and "IF absent".

After descrambling the information flow, the corresponding paraphase signals 034 and 734 enter the block

The NOV-3 codec, in which the unipolar stream is encoded into a quasi-ternary signal (in the NOV-3 code), which arrives at the NOV-3 Output connector.

It should be emphasized that the equipment can be used only if the entire digital schedule of the radio system is built in accordance with standard 5.703. In MITRIS, however, digital broadcasting is mainly carried out using the transport flow of the MPRES-2 standard. In this regard, a special interface device that transforms the stream is used to transfer computer data arriving to the BS MTRM in the communication standard 5.703 in a stream according to the MPRES-2 standard.

In MITRIS, the 09220 Model 09220 Opioid Opioid Device is used for these purposes, manufactured by Opioid Opioid Inc., USA, with the following main parameters:

Speed, Mbit/s: data transfer 34,368 informational 0)

Reed-Solomon code

T-19(208.88)

Marginal coefficient of errors" 106

Impedance, Ohm (unbalanced) 75

Connector vm

Dimensions, cm 4.5x48.3x55.8

Power consumption, W 25 x At which the device remains operational.

This device allows not only to form a one-way (simplex) stream of MPEC-2 for its multiplexing into the general digital stream arriving at the transmitter, but also to carry out duplex data exchange with public telephone networks.

Let's consider the digital equipment for stereo radio broadcasting, designed for the transmission of sound broadcasting signals via satellite, cable and radio relay communication channels. Thanks to the use of the audio signal compression algorithm according to the IZOLES 11172-3 (MOBISAM) standard in the equipment, a CD-quality channel can be organized at a speed of 192Kbit/s, a higher-class channel at a speed of 128Kbps, and a 1st-class channel - at a speed of 64 Kbit/s. At the same time, the maximum number of channels in a group stream of 2048Kbit/s can be as follows: with the quality of a CD - 5 stereo or 10 mono; the highest quality class - 7 stereo or 15 mono; first class - 15 stereo or 30 mono.

A standard digital joint with general-purpose equipment or connecting lines is made according to the p.703 standard. The NOV-3 line code makes it possible to connect this equipment to both radio modems and connecting cable communication lines. The cycle is organized in accordance with standard o.704. The permissible error probability per symbol in the receiving group stream is 107. There are built-in test generators to check the functionality of the channel equipment. The group equipment of the sections has 10095th hot reserve.

The transmission section of the equipment includes a phase modulator that generates an ORBK signal at a frequency of 52-88 MHz. When transmitting, relative coding, scrambling by Year is used. M.35 MSB-R and convolutional coding (length of the Kae7 code limit).

The receiving section includes a digital phase demodulator designed to receive IF signals in the range of 52-88 MHz. The convolutional code is decoded using the Viterbi algorithm.

In MITRIS, for directional stereo transmission, a radio modulator of Fig. 21 is used, designed to work as part of a radio relay system or MTRM. It has an output intermediate frequency of 7 MHz and is used together with a demodulator (on the receiving side) as a channel-forming device that provides the organization of digital channels for high-quality transmission of stereophonic broadcast programs between a radio broadcasting studio and a transmitter, a radio studio and a radio studio (exchange of phonograms), concert halls and a radio studio, with organization of reporting programs and recording of concert programs, etc. The modulator carries out analog-to-digital conversion of two signals of a stereophonic broadcasting channel with a frequency band of 20-20000Hz and subsequent FM carrier IF of 70MHz. At the same time, digital coding of sound signals is performed with a sampling frequency of 48kHz (in accordance with ICRC Year 646 and Year 606) and a resolution of 18 bits per count.

The technical characteristics of stereophonic broadcasting channels with a frequency band of 20kHz meet the requirements of Year. 505-4 ICRC:

Nominal frequency range, Hz 20-20000

Frequency response unevenness, dB, in the range: 20-125HZ -3...0.3 125-10000HZ 01 10000-15000HZ -0.8...0.1 15000-20000HZ -1...0.3

Harmonic coefficient, 905, no more than 0.2

The difference in levels between channels A and B of a stereo pair, dB, no more than: 20-15000Hz 0.1 15000-20000Hz 0.2

The phase difference between channels A and B of the stereo pair,..., no more than: 20-125HZ 5.0 125-10000HZ 4.0 10000-15000HZ 5.0 15000-20000HZ 7.0

Protection against noise, dB, not less than:

Weighted 63

Unweighted 82

Input resistance of the sound channel (symmetrical), Ohm 6oo0

The maximum level at the input of the channel, dBmoz -9

Gain (1kGu at 12dB level) introduced, dB 0

Protection against pronounced transient interference, dB, not less than: between stereo channels 70 between independent channels 74

Protection against cross-modulation products, dB, not less than:

Intraband because

70 Bezsmugovoi

The operating voltage of the IF signal at the output, MV 5255

Average earnings in full, hours E51010100)

Average term of service, 10 years

Stereophonic analog radio broadcast signals are transmitted with the help of analog-to-digital conversion and subsequent FM carrier of 7 MHz.

The radio broadcast modulator (Fig. 21) includes: matching amplifiers of the left and right channels of the UPLC and UPPK, a two-channel 18-bit analog-to-digital ADC converter, a galvanic decoupling scheme of the SGR, a device for temporary combination of UVO, an FM modulator, a converter voltage KN, power supply unit BZh and quartz generator KG.

The radio signal ZS1 to be transmitted is sent to the UPLC and UPPK, which serve to coordinate and balance the input signals, and together with the 2-channel ADC, they are galvanically isolated from the rest of the nodes with the help of the SGR of Her KN. Digital readings from the output of the ADC through the SGR are sent to the UVO, which forms a temporary cyclic synchronization signal, sets the channel readings accordingly and scrambles the output digital stream. Next, the digital signal is sent to the FM modulator, from the output of which the received signal from the IF 70MHz through the low-pass filter is fed to the output connector IF Output.

Subscriber terminals are receiving or, more rarely, receiving-transmitting equipment complexes designed to receive the BS information signal and transform it into a form suitable for direct use by the subscriber (television signal of the ZEKAM or RAI standard, digital data stream, etc.). Also, the subscriber terminal can provide a digital reverse communication channel to

BOS using a special cable modem connected to the telephone network (in the case of a purely receiving terminal), or using a transmitter (in the case of a receiving-transmitting terminal).

The composition of the subscriber terminal, as a rule, includes a receiving (receiving-transmitting) antenna, an external receiving module, access equipment and a connecting cable. The external receiver module is a down-converter that provides reception of a microwave or microwave signal, its down-conversion to the necessary IF, amplification and filtering of the signal. Usually, the module is combined with the antenna system and is located on the walls or roofs of buildings, less often - on special towers.

The access equipment of the subscriber terminal is located indoors and provides all service functions of the terminal. Its composition, depending on the purpose, may include television tuners, individual computer or network modems.

Receiving subscriber terminals can be individual or collective with the distribution of TV programs or data streams on the SNTV IF (0.9-2.15 GHz). If an individual terminal has a SNTV tuner, then a collective SNTV with IF distribution contains a number of tuners, according to the number of subscribers. The collective subscriber terminal with cable distribution in the meter and decimeter ranges contains a cable television station with units for converting signals of the range 0.95-2.15 GHz into standard AM television signals of the range 48-850 MHz, which are fed into the cable network. The terminal for receiving special information contains a demodulator-decoder corresponding to the type of received signals.

In order to protect against unauthorized reception and in the case of commercial use of the terminal, the BS is supplemented with an encoder and a computer with appropriate software to control the collection of subscription fees from users.

The function of the encoder is to introduce distortions into the transmitted television signal or audio accompaniment. The transmitted program package can be divided into several groups, which are coded in different ways, thus the user is given the opportunity to choose, that is, he can receive, and accordingly pay for, only those programs that interest him.

In this case, each subscriber terminal has an individual serial number entered in the computer memory. An encrypted package of programs transmitted over the air contains information from the central computer to each decoder connected to the network in the form of commands with instructions on which list of programs should be decoded for a given subscriber.

The computer automatically issues early invoices to subscribers as subscriptions expire, and in case of non-payment blocks the subscriber's decoder. At each moment of time, the computer operator has complete information about the progress of subscription to network services.

External receiving modules. The receiving modules of the MMO5 subscriber terminals are combined with the antenna system and convert the incoming 2.6 GHz AM signal into a signal of the decimeter operating range of standard television and radio broadcasting, which provides a simple interface with conventional television equipment. An example of such a module is the AOS IT5 sogr. converter, which has the following characteristics:

Noise coefficient, dB, no more than 1.7

Operating frequency range, MHz: input signal 2500-2686 output signal 662-848

KP, dB 3212

Irregularity of KP, dB 1.5

Local oscillator frequency, MHz 1838

Frequency stability of local oscillator, 30 kHz

Local oscillator phase noise suppression, dBn/Hz, when tuned to 10kHz -85

Maximum output level at radio frequency, dB(μV), when loading: single-channel 119 24-channel 90

Power consumption, W 4-6

Operating temperature range, "С -40...-80

Mass, kg 0.4

The receiving module of the MITRIS subscriber terminal uses the classic construction of satellite converters. The diagram of the converter is shown in Fig. 22. At its input, there is a low-noise transistor amplifier (MSHP) with a noise coefficient of no more than 1dB and a gain of 20-30dB. Bandpass filter after

The MSP suppresses the mirror channel and weakens the parasitic radiation of the signal with the frequency of the local oscillator.

The balanced diode mixer provides conversion of the input signal from the frequency of the reception band of 11.7-12.5 GHz to the IF adopted for SNTV in the range of 0.9-2.15 GHz. The IF signal is amplified by the output amplifier to the level necessary for its transmission over the cable.

The heterodyne is based on a transistor stabilized by a dielectric resonator.

MTRM systems of higher frequencies (28 and 41 GHz) mainly use converters with two frequency conversions. Moreover, in some cases, a special pilot signal is used to compensate for the low stability of millimeter local oscillators, which is generated by the BS transmitter and synchronizes the local oscillator of the subscriber receiver.

Fig. 23 shows the structural diagram of the 28GHz MITRIS subscriber terminal converter. Instead of communication probes, a frequency converter containing a balanced mixer and a local oscillator is mounted in the input waveguide. The mixer is designed for down-converting the frequency of the input signal in the 27.5-29.5GHz band to the 11.5-13.5GHz range. The output of the mixer is connected to the LNA input of the basic converter I M0-520823РЙ. To prevent leakage of the local oscillator signal, a blocking filter is used, which provides its suppression by more than 50dB. The heterodyne is made in a separate housing and is connected to the mixer circuit using a beam output.

The basic converter contains an input two-stage MSHP, a mirror channel filter and a microcircuit

AKD17525ТЧ4ЧС with an external stabilizing DR in a separate case. The AKD17515TCS microcircuit contains a balanced mixer, an active local oscillator circuit and a PU amplifier. The local oscillator frequency is 11.475 GHz.

The main parameters of the I MO-5S823BNY converter. are as follows:

Frequency range, GHz:

Workers 27.5-29.5

Weekends 0.9-2.15

Noise coefficient, dB 8

KP, dB 45-50

Frequency of the first local oscillator, GHz 16

Power consumption, W 2

It should be noted that at the input of the converter for the short-wave part of the centimeter range and the millimeter range of wavelengths, mixers are installed, which provide higher dynamics and a higher noise coefficient than converters with MSHP at the input. Installation of the MSHP allows, of course, to increase the maximum sensitivity of the receiver, but at the same time it leads to an increase in its price and a decrease in the dynamic range. The latter is undesirable in the EHF range, where due to significant attenuation of millimeter radio waves and small service areas, high dynamics of input receiving devices is required. In this regard, manufacturing companies usually offer several modifications of converters - with and without an MSHP at the input.

Transceivers of subscriber terminals can be divided into two types. The first type includes those that are made from two completely independent nodes: a receiving converter of the main MTRM range and a transmitter operating in another range and on another antenna. The second type is classic transceivers that use one antenna for reception and transmission. They are the most common.

Such a low-power short-range subscriber transceiver, Fig. 24, is used in MITRIS, providing the operating parameters listed below. However, the presence of a circulator and additional resolving band filters in it led to its increase in price. In order to reduce the cost of subscriber transceivers, a number of technical solutions have been proposed in terms of unbundling of reception and transmission paths.

Table 6

Technical characteristics of the transceiver

Parameter

Central signal frequency, MHz: output 11715 1735 input 1015 12485

Local oscillator frequency, MHz 10750 10750

Output power level with compression dB, W, not less than 4x103 -

Through frequency band, MHz, no more than 0) 0)

Suppression of side emissions, dB, is at least 10) -

Kp - 50

Noise coefficient, dB, no more than 4

The proposed integral sub-block of the microwave range allows combining the receiver and transmitter in one object. The sub-block includes a mixer and a local oscillator. Depending on the inclusion, the mixer (Fig. 25) works either as a down-converter or as an up-shift mixer. At the same time, the following signal parameters are provided.

Table 7

Mixer signal parameters of the transceiver sub-unit

Signal frequency, GHz: mixer 34.06 32.06 local oscillator 34 32 intermediate bo 50

Signal power, mW: mixer 1 20 local oscillator 10 100 intermediate 10 10

Access hardware. To receive analog television signals, tuners of satellite direct television and radio broadcasting are used. The tuner (internal receiving unit) converts the FM signal of the base station coming from the output of the converter (external receiver module) in the range of the first intermediate frequency (IF) into a standard television signal of terrestrial television and provides the user with the opportunity to select the desired TV program. The principle of construction of the internal unit corresponds to the classical scheme of the superheterodyne receiver, supplemented by the node for forming a standard terrestrial television signal. The tuner receives signals in the 0.9-2.15GHz band, amplifies them in advance and converts them into a second PU.

The necessary bandwidth is formed in the path of the second IF, the signal is amplified and sent to the FM demodulator. After demodulation, it is divided into video and sound signals, repeated demodulation of the sound carrier and the formation of a standard radio signal in one of the meter and decimeter channels of terrestrial television.

In the case of reception of a digital stream in the MPRES-2 standard, the reception equipment of digital SNTV is also used. Figure 26 shows a diagram of such a digital tuner. It should be noted that currently the satellite telecommunications market offers the widest selection of data devices manufactured by various companies. Consider the commercial digital internal receiver model 09223 of the company "Scientific Atlanta Inc.", designed for receiving, decoding and decompressing digital video and audio signals in the MPRES-2 standard. The technical characteristics of the receiver 09223 are given below:

Input frequency range, MHz 950-2050

Controlled frequency grid step, 250 kHz

Input impedance. Ohm 75

Suppression of the mirror channel, dB, more Ko)

Noise coefficient, dB, at - b5dB(mW) at input 15

The ORBC demodulation method

Audio output range: frequency, Hz 20-20000 dynamic, dB 80

Output impedance. Ohm 600

The number of stereo outputs is 2

The signal-to-noise ratio at the video output, dB, is at least 56

The IF band is variable and depends on the symbol rate (1.5-30.83)X106 symbols per second. Special computer boards widely used in satellite systems are used to receive only data streams

Thus, modern subscriber terminals of the MITRIS system can be equipped with inexpensive satellite SNTV and communication devices that have found mass use. They are fully compatible with equipment for receiving an analog FM television signal, digital information in the MPEC standard, or any data stream that uses non-amplitude types of modulation.

Repeaters. If it is impossible to serve the entire planned territory with the main BS transmission antenna due to the complex topography of the terrain, multi-story urban buildings, the presence of additional points reradiating the broadcast signal is required to exclude "dead zones" in which direct visibility of the BS transmission antenna is not ensured. Repeaters are used to broadcast such areas. They are active and passive.

Active repeaters (AR) are a maintenance-free radio complex consisting of receiving and transmitting antennas, as well as receiving and transmitting equipment. The DS of the transmitting antenna and the output power level of the repeater are selected depending on the required area of the service area. When choosing a place to install the transmission antenna, it is necessary to take measures to exclude the occurrence of interference to subscribers who are in the radiation zone of both transmission centers - the repeater and BS. For this purpose, the broadcast of the information signal from the repeater can be organized in a different polarization or at a different frequency.

Passive repeaters (PR) differ from active ones in that they do not have reception and transmission equipment and signals are relayed by antenna systems of various forms.

The structural diagram of the repeater without frequency conversion with transistor amplifiers is presented in Fig. 27. According to this scheme, a broadband AR IT5-605S (AOS IT5 Corporation) was built with the following parameters of the receiving and transmitting part:

Output power level, dB(mW) per channel: for 4 channels 25 for 8 channels 20 for 16 channels 17 for 31 channels 13

Input-output frequencies, MHz 2076-2111, 2150-2162, 2300-2400, 2500-2686

Input-output impedance. Ohm 50

Signal-to-noise ratio in the 6 megahertz band at 45 dB(mW) per channel, dB 55

Noise coefficient of the 1st amplifier, dB 1.5

Input signal level, dB(mW) per channel 60...-30

Range of automatic gain control (ACU), dB 0)

Power consumption, W 160

Fig. 28 shows structural diagrams of active repeaters (AR) with the possibility of relaying signals in two polarizations. Such ARs are used in MITRIS and have the following parameters:

Output power level, dB(mW) per channel, not less than 4

Range of input-output frequencies, GHz 11.7-12.5

Input-output impedance. Ohm 75

Noise coefficient of the 1st amplifier, dB 1.6

Input signal level, dB(mW) per channel 60...-30

Range of manual output power adjustment, dB 25.

The ARs considered above have a common drawback: the impossibility of using amplifiers with a large KP due to the connection between the antennas, which in this case can lead to self-excitation of the amplifier.

The use of spaced antennas with small rear lobes of the directional pattern and compensatory methods of suppressing reception through the side (rear) lobes allows you to get KP in AR of the same frequencies up to 120dB. However, these measures lead to the complication and increase in the cost of the repeater.

As a result of these reasons, AR with a frequency shift is more often used, which provides the necessary resolution between the receiving and transmitting antennas (Fig. 29). Here, the output of the round waveguide of the antenna irradiator is connected to the polarization selector, in which the signals with vertical and horizontal polarization are separated. These signals are sent to two corresponding converters, where they are converted into an intermediate frequency (IF) range of 0.9-2 GHz and amplified. The IF adder forms a group signal, the spectrum of which on the IF corresponds to the frequency spectrum of signals in the range of 11.7-12.5 GHz transmitted by the MITRIS CS. NVU - a signal with a power of at least 250 μW in the range of 0.9-2.0 GHz from the IF adder is fed to an electrically controlled attenuator. The microstrip attenuator is assembled on caseless p-and-p-diodes and provides smooth adjustment of the microwave signal in the range of 0-25dB. After that, the signal is sent to the amplifier, which in linear mode has a KP of 20dB. An up-shift mixer, assembled on a diode pair and tuned to extract the upper sideband, up-converts the signal. Its conversion factor is 8dB. The output of the mixer is a microstrip-waveguide transition, which allows it to connect to a PPF built on a section of a waveguide with a section of 1bhdmm with longitudinal diaphragms. The pass band of the filter is 11.6-13.5 GHz. The attenuation of the filter outside the passband when tuning at 100 MHz from the limit frequencies is at least 4OdB.

The output power amplifier is assembled on transistors and provides in linear mode a KP of at least 25dB and an output power of 500mW when the KP is compressed to TdbB.

The received microwave signal through the transition from a round to a rectangular waveguide enters the antenna from a circular DS in the azimuthal plane. The antenna makes it possible to transmit information from KP 15-16dB. The level of the input signal is set using a variable attenuator in the tuning process to obtain the required characteristics of the transmitted channels.

A feature of this active repeater is the use of a single local oscillator (bipolar transistor generator, stabilized DR, and power amplifier) for all paths (reception and transmission), which allows not to introduce additional frequency instability during reception and transmission, and also makes the repeater cheaper.

The receiving part of the AP data is similar to the previously discussed repeater part. Signals received in the range of 11.7-12.5GHz in two polarizations are converted separately down to frequencies in the range of 0.9-2.0GHz. Then they shift upwards in the range of 27.5-29.5GHz, intensify to a level of the order of 2-

ZdB (mW) per channel and radiated using the antenna in the appropriate polarizations (Fig. 30), or combined in the adder and radiated in one (vertical or horizontal) polarization (Fig. 31). In the latter case, a wider band of transmission frequencies (27.5-29.3 GHz) is required, which is more than twice as large as the reception one (11.7-12.5 GHz) due to the transmission of signals of two polarizations. In addition, the frequencies of the heterodynes of the transmission path, GHz, are related to each other by the ratio y53-1521.

Passive repeaters. A repeater made in the form of two interconnected ("back to back") antennas is considered ideal PR. All PR used can be divided into three main types: reflective, refractive and in the form of obstacles. In MTRM systems, mainly PR reflectors are used, which consist of one or two flat metal mirrors, located in such a way as to ensure direct radio visibility.

With the specified dimensions of the passive reflector, as well as with the specified dimensions of the antennas, the power of the received signal is inversely proportional to the wavelength in the fourth degree. Based on this, one cannot fail to note that when working in the microwave and microwave ranges, the sizes of passive reflectors and antennas can be much smaller than when working at lower frequencies. This makes it possible to reduce the influence of deviations of the main lobe of the DS antenna from the line of sight, which inevitably occurs when the width of the lobe is very small. PRs are almost not used at frequencies below 4GHz and, on the contrary, are widely used at frequencies above 14GHz. The efficiency of PR operation is especially high in the microwave range, where it is possible to display waves propagating almost without loss. This property is widely used in cellular systems

MTRM to cover the "darkened" areas of the broadcast zone of one BOS.

Distribution radio relay lines. Technical achievements of classic line-of-sight radio relay systems in rapidly developing satellite systems are not only used to one degree or another, but are also widely used in terrestrial communication lines between specific points.

Currently, television and digital radio relay systems make it possible to create various distribution topologies of buildings and many microwave radio lines. Given that the distances between broadcasting stations and television and radio studios are within 1-10 km - for urban areas and 10-35 km - for rural areas, their connections are made mainly by RRL with relatively short spans. RRL with short spans is a rapidly developing branch of modern telecommunication technologies. Such radio relay systems, due to rapid deployment and low construction costs, are effectively used not only in MTRM, but also in cellular (cellular) networks of mobile communication, in computer networks. They organize the exchange of information flows between enterprises, ATS, banks, etc.

Radio relay systems can have different configurations: from one span without redundancy with the simplest control system to several dozen spans of a radio line with a complex system of control, redundancy, allocation of streams at intermediate and final radio relay terminals. The capacity of the schedule of the radio relay system can be reserved (1-1) and non-reserved (1-0) - basic.

Redundancy according to scheme 14-41 is obtained when using frequency diversity or hardware redundancy.

The configuration of any terminal (node of the radio relay system) is created so that it can provide: - retransmission of a digital stream or television channel - at 70 (140) MHz by direct connection of radio units to each other; - access and the possibility of selecting digital streams or a television channel using a special access module in the hardware room; - regeneration of the digital stream without selection in radio blocks and its retransmission. The basis of such systems are RRS, which provide the exchange of information flows (from 2 to 34 Mbit/s), digital

PRS or a full-color television channel with four subcarriers (analog PPO), when the use of cable transmission lines is difficult, and an optimal solution is needed for building a local or zonal, mobile or fixed digital and television network.

PRS are designed for high-quality communication, inexpensive operation and maintenance of which can be supported by a small staff of specialists. PROs are used as a basic system in the development of special radio transmission networks that adapt to certain reliability requirements and features of the given schedule of each user.

The characteristics of all PRCs comply with the recommendations of the ITU-R. These recommendations are also used when choosing a plan for the placement of radio trunk frequencies for radio relay systems. The layout plan for radio trunks of one frequency range is shown in Fig. 32.

Composition of radio relay stations. In the general case, the PRS consists of three main parts: a radio unit for external installation, an antenna with a support-rotating device and an access module located in the room (hardware).

Table 8

Frequency placement of radio trunks for line-of-sight radio relay systems

I Formula for Shag divlazo n. calculation of frequencies| grid | Mpom-prd and them and them p

In the raster

Tya-yu-154--414p 7425-7725 (ney 414p 7Bt5 7435 | 7547 | 7503 | 775 (6385) osyutb1tavp 28. | 154 | 7442 | 7554 | 7596 | 7707 | 1-5

Ta-yo--7-28p

Ta-yo-108.5--7p Y 8275-8500 |in-yok17.547p vav7 5 b2v6 8363 ) vyy | 8189 (864) 00 bones, or 14 | 419 | in the air | 8363 | va12 | wav? | 1-6

Ta-yo--17.5--14p 10700-11700 |R-t0-545--40p

E.387-6 i-i 15440p 11200 10735 | 11135 | 11265 | 11665 | 2.3-12 12750-13250 | Hp-io-259--28p

E497-4 vp-ion7- 28 12996 12765 | 12961 | 13031 | 13227

Tn-to2702-14p 14400-15350 |Ta-y0-10--27.5p 11701 tyat7 of spotted uzy (g.636-3) Ta-to-2688-- 28p - -ton3626-28(16-p 28 490 14417 | 14837 | 14907 | 15327 1-16 17700-19700 | iT-0-1000-27.5p

E.595-3 v-yuz10427.5p 18700 1010 117727.5| 18662.5 | 18737.5 | 19672.5 21200-23600 | Ha-0o-161-- 28p 21196 1232 | 21231 | 22337 | 22463 | 23569 (E.637-2) r-1...685 21238 | 22330 | 22470 | 23562

In-juzht convened 57 | 36897 | 37289 | 38129 36 000-38300 | yip-y0--1233--28p (7497) f-yunth about 7 7 Govy181 zbova | zt45 | will call

Ta-iTo--1233--56p x The number of Recommendation MSE-R is indicated in brackets.

The radio unit performs all the functions of a transceiver and is a hermetic container in which the high-frequency modules of the reception and transmission paths, the service access module (control and control board, service communication), and the internal power source are placed. The container provides protection against external climatic, mechanical and electromagnetic influences. Usually, the radio unit is combined with the antenna, but separate installation is also possible. The interface for the antenna is standard waveguide channels of the corresponding frequency ranges. The radio unit contains a connector for connecting a coaxial cable, a technological remote control and a power cable (if necessary).

The antenna with the radio unit can be adjusted for vertical and horizontal polarization using a pivoting device. At the same time, accurate adjustment in azimuth and elevation angle is ensured. The diameter of standard antennas used with protective caps is within 0.3-1.m.

The access module (MD) in the CRS provides an interface for connecting the radio relay network with public networks, direct subscribers, departmental PBXs, mobile communication stations and computer networks. With the help of MD, service personnel have access to technological channels for technical maintenance and obtaining information about emergency situations and the condition of the nodes of the radio unit. MD CRS consists of a base unit (BB) and a multiplexer.

BB has a number of modifications depending on schedule capacity and reservation conditions. It performs the function of a digital modem - it connects the MD to the radio unit via frequency converter (70 or 140 MHz) - or a connection device using a digital stream in the NOVZ (AMI) code. The BB has a connector for connecting cables from the radio unit and the equipment for forming a digital stream, as well as for connecting a technological remote control with a telephone handset, a power source. On the front panel of the unit there is a light indication, network status switches and remote control. For the simplest radio lines without redundancy with a schedule capacity of 2.048 and 8.448 Mbit/s, if the modem part is installed in the radio unit, the BB may not be used.

The multiplexer combines a number of streams of 2.048 Mbit/s into one with a larger capacity (8.448 or 34.368 Mbit/s).

The interface of the multiplexer at the transmission speed of 2.048 Mbit/s corresponds to the standard 5.703.

In television PROs, the MD is a standard television modem with a frequency of 70 MHz. For each MD, such a configuration can be created so that RRS can: serve the required number of directions (radio lines); operate radio units with hot backup (1-41) and without such (1-0);

use spans in different frequency bands with different bandwidth in each direction.

Small-sized PRO. Currently existing small-sized PPOs can be divided into three types. The first type includes PRS consisting of two independent parts: a transceiver unit (BPP) - a radio unit - and a standard modem (in the case of a TSR - a 2x4 or 2x16 multiplexer). The modem is connected to

BPP using a signal transmitted via coaxial radio frequency cables to the second IF of the BPP (70 or 140 MHz). This scheme of building a station is quite universal and the most widespread. It allows you to use the same BPP to transmit both digital information and an analog signal in the corresponding band. In this case, digital or standard analog modems are used, respectively. For a radio line with hot backup, created on the basis of the first type of PPO, the number of duplex trunks is recommended no more than 3-1, optimally - 141. This construction scheme is most preferable in systems where simultaneous operation or hot backup of more than four duplex trunks is required. It is widely used, for example, in stationary multi-channel satellite communication systems, as well as in MITRIS transmitters. This type of station is quite specific and does not have the same prospects for use in zonal digital duplex radio lines as the first two types, especially if their large-scale production, provision of a unified telecontrol and telesignaling system, and the use of a frequency synthesizer are required. However, this construction is preferred when creating a simple simplex television line, when only frequency terminals for transmission and reception are needed, as well as a set of frequency-independent transmission (reception) single-channel trunks.

The development of communication systems, especially the transmission of digital information, currently requires the creation

CDS - the most technological and unified, with the possibility of choosing a certain operating frequency using a built-in frequency synthesizer (FM). Such a CRS can be built according to both the first and the second type.

The basis for the construction of the CDS transceiver unit is a scheme with two transformations and the use of a frequency synthesizer (Fig. 33), in which the possibility of connection with the access equipment as per

PU 70 or 140 MHz, as well as in the form of a digital stream.

Structurally, the BPP consists of a unified hermetic housing with connectors, internal microwave and digital modules, remote signaling and remote control boards, and a power source.

The high-frequency input-output of the BPP is a standard waveguide flange corresponding to the operating range of the station. The input and output of the receiver and transmitter paths, respectively, are connected to it from the inside through a diplexer.

The receiving microwave path includes an input converter (MSHP, mixer and IF pre-amplifier), a selective IF amplifier, a second conversion mixer and an output amplifier with an AGC.

The transmitter tract on the side of the microwave output consists of a step-up converter (power amplifier, selective up-converter), a selective IF amplifier, similar to the receiving one, and an amplifier with an AGC.

The BPP interfaces with the access equipment by means of the exchange of digital streams, which are formed and received in the block by the digital boards of the codec, modulator and demodulator.

With the help of symmetrical cables, the BPP is connected to the BB, for indicating the control parameters of the CDS, generating control signals, frequency support and the service communication channel, providing power to the BPP.

The BPP itself provides control and management of the output power of the transmitter, switching the frequency of the generator with, setting the frequency of the MF and monitoring the presence of an information signal at the output of the IF path.

In addition, it is possible to install an input loop before the receiver and after the transmitter - converters, as well as in the IF path. Microwave paths are designed for transmission and reception of signals with relative phase and quadrature amplitude modulation types.

BPP blocks and nodes are unified for all frequency letters within the same frequency range, which makes it possible to use the same BPP in it. For the reconfiguration of the "lower" BPP (the operating frequency of the transmitter Iiprd is less than the frequency of the receiver Iprm) in the "upper" (Iprd"/prm) selective amplifiers of the IF paths of the transmitter and receiver, which determine the signal bands of the first IF/hpchin and i/pchiv (indices "n" and "v" mean, respectively, the lower and upper frequency levels), set by changing places. At the same time, in order to prevent a change in the second IFs ipchaprm and Гпч2прд, the frequency of the generator C under the influence of the control signal takes one of two values - depending on where its frequency is used. Yes, in the transmitter path

Tg1-TlpchinyaAIprm-prd-TPChgprm and in the receiver tract

Tgo-Tpchin-Yipchaprm de Aiprm-prd - diversity of operating frequencies of the reception and transmission path.

It should be noted that for the BPP construction scheme under consideration, there is a clear dependence between the operating frequencies within the unit. For example, having determined the first lower IF and the second IF of the receiving path (70 or 140 MHz), you can calculate the first upper IF and the second (input) IF of the transmitter path:

Tpchiv-ilpchy nya Avprm-prd

Tpchaprd--AIprm-prd- TP Chgprm

As a local oscillator for microwave converters of the reception and transmission paths, a frequency synthesizer block (SU) is used, the value of a specific operating frequency of which can be determined by the formulas: when using the frequency of wheat in the transmitter path -

Toch-Tprm--AIprm-prd-Tpchyn, IF Iprmesi prd;

Tech-Gprm- AEprm-prd- Chin, if IprmoGprd" when using the pchin frequency of the receiver path

Tocheprm-TchChAn

If it is necessary to connect the described BPP to a standard modem at a frequency of 70 or 140 MHz, it is enough to remove the digital boards from the block (except for the control and management board), to one generator, which is from it, to additionally install it from it. Installing a second generator will allow you to get two identical second IFs:

Tpchapri--YipchChgprd: 7 O (140) MHz. The output of the receiving and the input of the transmission paths are connected to the modem through adapters using coaxial cables.

Equipment of radio relay stations. At this time, there is a wide selection of equipment for radio relay systems of domestic and foreign production. All of it complies with the IEC-R Recommendations and provides almost the same electrical parameters. The difference between domestic devices and the equipment of leading foreign manufacturers is lower cost and lower service provision. The last difference is not fundamental for the construction of local distribution radio lines and should soon completely disappear due to the emerging modernization of domestic radio stations. The parameters of domestic RRS are given below.

Image channel

Impulse characteristics

Relative deviation of the range of the sine-square pulse from the range of the reference white pulse, 95 5.0

The relative amplitude of the first negative emission of a sine-square pulse, 90 5.0

The relative amplitude of the second positive emission of the sine-square pulse, 90 5.0

Relative unevenness of the flat part of the rectangular pulses of the line frequency, 90 1.75

Relative unevenness of the flat part of rectangular field frequency pulses, 90 12.0

Difference in amplification of brightness and color signals, 9Uo 5.0

The difference in time between the brightness and color signals is 60.0

Amplitude-frequency characteristics (frequency response)

The relative deviation of the packet span from the reference pulse span, 90: 1st packet 0.5MHz 6.0 2nd » 1.0MHz 6.0 3rd » 2.0MHz 6.0 4th » 4 0MHz 6.0 5th » 4.8MHz 6.0 6th » 5.5MHz 20.0

Nonlinearity of the brightness signal, 90 2.5

Differential gain, 905 1.0(5.0)

Differential phase,..." 1.0(5.0)

Relative deviation of the range of synchronizing pulses from the nominal value, 9o 5.0

Color-brightness cross distortion, 90 1.75

The ratio of the brightness signal to the weighted fluctuation interference, dB, not less than 62.0

The ratio of the brightness signal to the background interference, dB, is not less than 50.0

Input impedance. Ohm 7531

Input-output level, B 1

Audio channel

Reproducible frequency band, Hz 30 15,000

Frequency response unevenness, dB, in the frequency band: 30-125Hz 0.3...3.0 125-10000Hz 0.3 10000-14000Hz 0.3...1.3 14000-15000Hz 0.3...2, 0

Harmonics coefficient, 95, no more, at frequencies: up to 125Hz 1.0 125-2000Hz 0.5 2000-4000Hz 0.5

Protection against weighted noise, dB, not less than 57.0

Protection against pronounced transient interference, dB, not less than 74.0

Frequencies of sound carriers 11...14, kHz 7360, 7765, 8215, 8710

Impedance, Ohm: input (symmetrical) 600260 output low 300530 7 Per year. MKKR 505-4 signal level - 12dB max.

The television PRO includes: an antenna with a rotary tuning device, a radio module (transmitter or receiver) and a television modem (modulator or demodulator). In accordance with Fig. 34, the mobile PPO contains a radio unit, an antenna, a modulator (demodulator), a tripod and a radio frequency cable.

The transmission part, which consists of a transmitter and a modulator, almost completely corresponds to the considered BS MITRIS single-channel transmitters, so we will consider only the receiving part of the PRO - the receiving radio unit and the demodulator. In the receiving radio unit, the received low-power microwave signal is filtered, its subsequent amplification and single-stage conversion into a 7O0MHz RF signal is carried out.

First (Fig. 35), the input microwave signal with a level from 5-10"! to 3-109W and a frequency that depends on the literal implementation of the block, through a waveguide seal, enters the band microwave filter on the DR, which suppresses the side components arising during signal reception. The initial losses of the filter are about 1.5-2dB. From the output of the filter, the microwave signal enters the input of a low-noise amplifier built in a microstrip design according to a linear three-cascade scheme. The KOE 1870 transistor of the MES company is used as an input transistor. Other transistors are developed in NPP "Saturn" KP of the amplifier - of the order of (2552)dB, noise temperature - within 180-200K, output KXHN - no more than 1.25.

The signal from the amplifier enters the input of the mirror channel filter (FZK) made on the DR, which has several modifications for different frequencies of the block and is directly connected to the input of the mixer, which carries out a single-stage conversion of the microwave signal to a 70 MHz IF. The mixer is made in a microstrip version according to a two-balance scheme using planar Schottky diodes. A microwave signal with a power of 8-10 mW from the output of a solid-state local oscillator, the design of which is similar to the design of the local oscillator of the BS MITRIS transmitter, reaches the local oscillator input of the mixer.

From the output of the mixer, a signal with a frequency of 7O0 MHz goes to the board of the intermediate frequency amplifier (IFMA), made on caseless field-effect transistors with a high dynamic range. The KP UPH is of the order of 30-34dB, the noise coefficient is about 200K, the input-output KSHN is no more than 1.25. From the output of the amplifier

IF signal is sent to the amplifier-corrector, which carries out its further amplification, correction of GVZ and automatic adjustment of the signal level. The KP of the amplifier-corrector is equal to 40dB, the depth of the AGC is 35-40dB. From the output of the amplifier-corrector, a signal with a frequency of 7ΩMHz and a level of 0.38 goes to the separation board and then through the coaxial cable of reduction - to the demodulator. The supply voltage of the 4248 is supplied to the receiving unit from the demodulator also through the step-down cable and through the separation board to the power board.

There is a connector in the block to control the supply voltage. AGC voltage (0.8-1.08) is applied to one of the contacts of this connector, which characterizes the unit's performance and serves for accurate installation of the receiving antenna.

The demodulator is designed for demodulation of the IF 7 MHz signal, selection of the video signal and audio signals from the group signal, as well as the formation of the voltage of the remote power supply of the receiving radio unit. Technical data on the demodulator are considered only in combination with the modulator, which together form a television channel. The demodulator includes the following devices: a demodulator block, a modem control board, two sound boards, power supplies from the 2208 and 4248 networks.

A 70 MHz FM signal of the IF input is received at the input of the IF input demodulator. In the demodulator block, the following are performed: demodulation of the incoming FM signal, allocation of a group signal (television video signal and up to four audio signals), its restoration in accordance with Year. 405-1 MKKR, frequency separation and formation of television video signal and sound signals at carrier frequencies. The Video Output 1 and Video Output 2 block outputs receive standard television video signals of positive polarity with a nominal level of 18 in the span.

Signals at subcarrier frequencies through two channels are received at the inputs of the sound boards, in which the frequency selection and demodulation of the two channels of sound support are carried out separately. The received sound signals are sent to outputs Sound 1-4, the nominal level of which is UdB (mW) at a load of 600 Ohms.

The demodulator block has the following technical characteristics:

Input resistance, Ohm 50

Change in the input voltage of the 7ΩMHz inverter within the range of 14-240V

Noise coefficient, dB, no more than 10

Sound carrier channel (Sound 1 4)

Attenuation of frequencies below 5 MHz and above 11 MHz relative to 8 MHz, dB, not less than 40

Voltages on a matched load of 75 Ohms with a deviation of -065 MHz, MV 51

Irregularity of frequency response in the 7.2-7.8 MHz band, db, no more than 0.5

Attenuation of 3rd order intermodulation products, dB, not less than 70

Video channel (Video 1-2)

Nonlinearity of the demodulation characteristic during deviation

ZMHC, because, no more than 0.7

Differential gain at a deviation of -28MHz and a modulating frequency of 4.43MHz, 9o, no more than 1

Differentiated phase at a deviation of -8MHz and a modulating frequency of 4.43MHz, 9o, no more than 0.5

Non-uniformity of the frequency response in the 25Hz band - 0.2 and - 1ΩHz, dB, no more than 0.5

Irregularity of GVZ in the 150kHz-5.5MHz band, no, not more than -4X0

Attenuation of frequencies higher than 7 MHz relative to 5.5 MHz, dB, not less than 39

Output impedance. Ohm 75

Digital distribution radio relay systems of small and medium traffic capacity (2, 8, 34 Mbit/s) provide transmission between certain points of any information in the form of digital streams according to the hierarchical structure established, mainly, by the p.703 standard (Fig. 36) . In this connection MD

TSRs are strictly regulated in terms of their external interface, which makes it possible to use a wide range of standard MDs for communication equipment or computer networks. An example of such communication equipment can be the АЦТ-34 equipment. Special converting equipment, such as roggo, is used to coordinate the digital transmission communication protocol (interface b.703) with the transport flow of MPES-2.

TSRs belong to the first and second type of RRS, have a single hermetic radio module for reception and transmission paths, special service communication boards, telecontrol and telesignaling. Thus, the presence of radio relay stations fully compliant with MSE-R recommendations and competitive among foreign analogues makes them the most preferable when creating local distribution networks for

MTRM. This is confirmed by the constantly developing MITRIS distribution infrastructure.

As a conclusion, it should be noted that there is now a trend of a planned general transition to a digital form of transmission of the stream of television and radio signals, which is based on modern compression methods without a noticeable deterioration in the quality of the original analog information. However, there is a certain threshold of compression of the digital stream, after which the level of quality of the transmitted television and radio signal is significantly reduced.

In this regard, digital transmission methods require either the presence of broadband radio channels, or the use of very complex high-level modulation methods. The latter leads to the need for a complete replacement of the existing broadcasting equipment and a significant increase in the price of receivers for subscribers. Thus, the introduction of terrestrial digital television in Europe with the use of complex methods of high-level modulation, according to preliminary estimates, will lead to the need for each subscriber to purchase, in addition to the existing, new, more modern receiving TV and radio equipment in the amount of about 12,000 dollars

USA. It is based on this that the most intensive introduction of digital television occurs, mainly, in satellite broadcasting, which uses simpler modulation methods with the use for digital broadcasting of the frequency bands of analog FM broadcasting in the NVU band. Terrestrial microwave television and radio information systems, including MITRIS, are capable of retransmitting both analog and digital satellite television and radio channels with equal efficiency. These systems are the most promising for the gradual transition of terrestrial broadcasting from analog to analog-digital and digital forms in the future. already 4 3 4 1 2 and 6 1 t 7 2 K

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