Collective reception systems for satellite television programs. Collective satellite television Installation of collective reception of satellite television

Methods and means of transmitting a television signal

For the first time a moving image was transmitted over a distance on July 26, 1928 in Tashkent by the inventors Grabovsky and Belyansky. Although the resulting images were rough and unclear, it is the Tashkent experience that can be considered the birth of modern television. The first television receiver in history, on which this experiment was carried out, was called the "telephoto".

In the 30s of the twentieth century, work was carried out on the development of television both in the USA and in Germany. First broadcast in live tested at the 1936 Olympics in Germany. In the USSR, the most experienced television broadcasting session took place on April 29, 1931. In 1937, the first television center was organized on Shabolovka Street, which since 1938 has been carrying out experimental television broadcasting based on electronic systems, and since 1939 - permanent television broadcasting (the first broadcast was a film showing the opening of the 18th Congress of the CPSU (b)).

Thus, more than 80 years have passed since the moment when man first managed to transmit a moving picture over a distance by means of a radio signal. Since then, television technology has advanced so far that it is becoming increasingly difficult to trace their connection with the good old "box" connected to a common antenna. Currently, there are different ways to deliver television content to the consumer: by transmitting a signal over the air using ground stations (NS), through artificial earth satellites (AES) and through cable TV systems.

Terrestrial television

Satellite television

Cable TV

Equipment for reception, distribution and broadcasting in SKPT

Collective television reception system (CCPT)

Appointment of SKPT
The collective television reception system (CCPT) is designed to receive on-air, satellite, cable television programs and broadcast them over the cable distribution network of the building. (SKPT) provides the opportunity for each subscriber to watch television programs broadcast from ground-based transmission centers, with artificial satellites land (ISZ) and cable operators.

In collective television systems, collective should be understood as the simultaneous reception of certain channels (for example, satellite channels, FM radio channels, terrestrial channels) from one antenna complex simultaneously by several households, regardless of the number of subscriber points available in each household.

The main trend in the development of the telecommunications market is the desire to create a global information network. This network is designed to meet the growing demand for communication services. Advanced and economical effective solution achieved through the creation of individual and collective (SKTP) television reception systems.

The system of collective reception of a television signal is a complex of hardware that receives, converts and distributes to its subscribers terrestrial television programs in various frequency bands, transmission of satellite channels, VHF FM broadcasting, and organization of an interactive television system. The structure of SKTP includes the following components: antenna system, including channel modulators; all-wave modulators; head station of television reception; broadband cable distribution network (including subscriber television outlets, cables, taps, splitters, house amplifiers, etc.).

Collective television reception systems differ depending on the functions performed: a collective antenna for several apartments, a city cable network (for analog solutions), an on-air system direct amplification, matrix satellite system, interactive IP-TV.

A collective system is more profitable than an individual one per subscriber, while it has enough high quality reception. Such systems can be easily scaled up. So, you can add high-definition satellite channels to the collective system for receiving conventional television. To do this, you need to install an additional dish, and new channels will automatically become available to all subscribers. One fiber-optic cable can connect high-speed Internet, as well as television, telephones, etc.

Currently, the following methods for constructing MATV (master antenna television, collective television reception system) are known:

1. Systems with a collective antenna and a common amplifier. They consist of a complex of terrestrial antennas, a multi-input amplifier, and a distribution network. A complex of antennas for different wavelengths allows you to receive TV programs that are broadcast in various frequency bands with horizontal and vertical polarization of radiation. A multi-input amplifier (otherwise Multiband) provides signal addition for antennas of different bands, and different signal amplification is required for different television bands. Multiband amplifiers are equipped with several inputs to which antennas of different ranges are connected; adjustment is performed separately for each input. The power of the amplifiers depends on the number of subscribers (several apartments, an entrance, an apartment building). The Multiband amplifier, however, does not allow you to equalize the levels of different channels within the same range. Therefore, the system works correctly if there is only one amplifier in it.

The distribution network, consisting of cables and dividers, serves to deliver signals from the amplifier output to subscriber devices. For subscribers located on different distances from the amplifier, are used different types power dividers - into equal (splitters, splitters) and unequal parts (couplers, couplers).

Such systems are inexpensive, compact and easy to operate, easy to scale, but their parameters make them convenient only for a relatively small number of subscribers.

2. A more complex system is SMATV (Satellite Master Antenna Television), a terrestrial system with a direct amplification headend for collective television reception of television terrestrial and satellite programs, in which the signals of each channel are processed separately. SMATV can serve both an apartment building and a microdistrict. The heart of the system is the direct amplification headend. The headend is a modular design consisting of a base unit or chassis, on which one channel amplifier module is installed for each channel. The system equalizes the levels of all TV channels (per-channel processing takes place). An equalized group signal can be distributed to a large number of subscribers, amplifying it many times.

Even in difficult reception conditions, SMATV ensures that subscriber outlets receive high-quality signals from all TV channels in the city. SMATV integrates with the community satellite system; in addition, you can add own channels. The system can, for example, display an image from a surveillance camera on consumer screens. But the price of a headend SKPT is higher than the price of a system with a common amplifier, because each TV channel needs its own channel amplifier module.

There are the following methods for constructing systems of collective simultaneous reception SMATV):

1. Matrix systems (Star Distribution) are collective satellite systems with maximum capabilities and the most convenient in operation. However, since they are the most expensive and bulky, they are used mainly for a small number of subscribers. The main components of Star Distribution are multiswitches (matrix antenna switches). The multiswitch has an input for a conventional television antenna (cable television signal), 4, 8 or 16 inputs for satellite antennas, a certain number of subscriber outputs (from 4 to 16). The control signal from the subscriber's receiver determines to which satellite input the subscriber's output will be connected. Each subscriber output always has a conventional television signal. Each subscriber, independently of other subscribers, has access to all channels of all satellite antennas of the system.

In some cases, to connect one satellite dish to a matrix system, it is necessary to use not one satellite input, but several, which depends on the selected satellite, and therefore on the polarization of the radiation and the frequency range. For example, in order to provide collective reception of the Tricolor and NTV-Plus programs (Eutelsat W4 / W7 satellite), two satellite inputs are used, for receiving European HotBird satellites - four, for receiving high-definition television (Eurobird-9 satellite) - one entrance.

Star Distribution topologies (ordered in ascending system capacity):

Linear matrix system. To increase the capacity of such systems, cascaded multiswitches are used, which, in addition to subscriber outputs, have loop-through (trunk) outputs. The main outputs repeat the input television signals of conventional and satellite television. The next multiswitch, which can be terminal, or another cascaded multiswitch, is connected to the main outputs.

Radial matrix system. Splitters split the signals from the TV antenna and satellite dishes; the separated signals are sent to several multiswitches.

Combinations of linear and radial systems. Television signals from sources are divided radially and fed to the inputs of several linear chains of cascaded multiswitches.

Advantages of matrix systems: it is possible to collectively receive signals from several satellites, arbitrary channels from all satellite dishes that are connected to common system; the receiver is set up and used in the same way as when using a personal antenna. Cons: the use of multi-cable backbone wiring, this complicates installation; high cost of equipment.

2. Single-cable systems of collective television reception. The main wiring of such systems is carried out with one cable, and instead of complex and expensive matrix switches, inexpensive compact dividers are used, which determines the ease of installation and low cost of the system. However, the possibilities of single-cable systems are limited.

Schemes for constructing single-cable collective systems are classified as follows:

System without frequency multiplexing: allows collective reception of programs of one satellite in one frequency range and with one polarization of radiation. It uses the same satellite dishes and converters, as for individual reception. To compensate for the signal loss that occurs when the signal is divided between subscribers, a satellite amplifier is needed. TV dividers must be broadband and support the satellite band (up to 2150 MHz).

Varieties of single-cable systems:

Single Cable Solution - single-cable system with a special converter (with a built-in frequency multiplexer for two signals of different polarization) or with an external multiplexer. Such systems are simple and low cost, but they are used only in cases where the satellite channels of interest to the subscriber are at close frequencies. In Single Cable Solution n Automatic tuning is not supported.

IF-IF Processing is a one-cable system with a satellite converter headend. More complex and expensive system. Allows you to receive programs from various satellites (with a limited number of channels). A distribution network with broadband dividers and one trunk cable is used. The head station (a set of converter modules that process the signal at one carrier frequency) is installed between the distribution network and satellite dishes. With the help of converter modules, it is possible to combine signals of various channels from satellites operating with different polarizations in different frequency ranges into one cable. The head station controls one virtual satellite, on which all subscriber programs are installed. Disadvantages: expensive headend equipment; auto tuning is not supported.

In today's article, we will tell you whether collective television reception system as part of the common property of an MKD, who should be involved in its maintenance and repair, and whether the payment for this service should be included in a single payment document.

Collective television reception system

The Ministry of Construction of the Russian Federation answered whether the MA is doing the right thing when they include a fee for the collective television reception system (hereinafter referred to as SKPT) in a single payment document.

It turned out to be correct. True, if this is due to the costs of maintaining the OI in the MKD.

As you remember, according to paragraph 3 of part 1 of Art. 36 LCD RF and paragraphs. "e" clause 2 of the Rules for the maintenance of OI in the MKD (Government of the Russian Federation of August 13, 2006 N 491) the common property in the MKD includes:

mechanical,
electric,
sanitary and other equipment of MKD,

serving more than one location. Also in paragraph 8 of these rules of the SKPT are named information and telecommunication networks, whose outer boundary coincides with the outer boundary of the MKD wall.

It seems that the listed factors indicate that the SKPT is part of the common property of the MKD, because it serves more than one premises in the MKD. However, it is possible to definitely attribute the SKPT to the common property in the MKD only if the house was equipped with the SKPT:

during construction - and this is confirmed by project documentation;
during operation - based on the decision of the OSS.

If the SKPT is installed in the MKD at the expense of individual owners or at the expense of the telecom operator as its own equipment, then in this case it cannot be included in composition of the common property of MKD. This statement is true even though the SKPT in this case still serves more than one premises.

Communication service and SKPT maintenance service

The Ministry of Construction of the Russian Federation notes that maintenance services for SKPT and communication services for television broadcasting are different concepts, and they are performed by different persons.

So, the communication service is regulated by the Federal Law of July 7, 2003 N 126-FZ. The service is performed by telecom operators on the basis of an agreement on the provision of telecom services:

the contract is concluded with each owner - on the basis of an application and in writing;
the contract lists the services provided, the system, procedure, terms and form of payment;
the right of the subscriber to refuse to pay for communication services for purposes not provided for by the contract is noted.

Regarding maintenance and repair SKPT, the provision of this service is controlled by housing legislation. Contractor - a person responsible for the proper maintenance of the common property in the MKD. In the MKD, which is managed by the MA, such a person is the MA.

Fee for maintenance and repair of SKPT

In this case, the maintenance and repair of the SKPT takes place in accordance with MKD management agreement. The work is carried out on the basis of the relevant decision of the OSS. As in the case of other items that make up the common property of the MKD, all owners of the premises of the house bear the costs of maintaining the SKPT.

To do this, they pay a fee for the maintenance of the dwelling to the address of the MA. The amount of the fee for the maintenance of a dwelling is set at the OSS and is calculated per 1 m² of the total area. It is charged from all owners, regardless of whether they use SKPT or not.

It turns out that such items in the receipts as “TV antenna”, “Use of a TV antenna” or “TO and TR of the KTP system” do not apply to the costs of maintaining the OI in the MKD. This is the amount of the subscription fee for the communication service, and it, in turn, is set by the telecom operator.

In this case, the owners of the MKD premises have the right to refuse communication services for the purposes of television broadcasting and not use the SKPT - i.e. the right not to conclude a contract for the provision of services or to terminate it.

The Ministry of Construction of the Russian Federation indicates that if executed in writing contracts with a telecom operator no, but at the same time subscription fee for communication services is included in a single payment document, the owner has the right to demand that it be excluded from a single payment document. After all, no one is obliged to pay for services that he does not use.

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They are very different, both in size and purpose: from a collective antenna for two or three apartments to a cable network for the city, from a direct amplification terrestrial system to a matrix satellite system. IN Lately systems of interactive IP-television are becoming more and more popular. Previously, this was a very expensive solution that only major operators communications and Internet providers. Now it is possible to build a fully functional IPTV network for a residential complex or hotel, at a cost comparable to a high-quality analog SKPT.

Why is a collective system better than an individual one?

Price. The price of a collective system in terms of one subscriber is less than the price of an individual system with the same capabilities. This is natural, since part of the equipment is used by all subscribers jointly and is bought “share”.
Quality. Reception of television in a modern city is not such an easy task. In general, high-quality reception requires serious equipment, which is too expensive for one user. Residents of an apartment building can afford to install good equipment and pay for quality installation.
Service. Maintaining an individual system in working condition is the concern of its owner only. Such systems are either not serviced at all, or each tenant has his own "master" who monitors only "his" system. As a result, several systems coexist in one house, built by different companies, on different equipment and at different times. As a rule, there is no documentation and marking. Each "master", having come to the house for the first time, is forced to deal with a hodgepodge of cables in low-voltage shields. The collective system is mounted by order of the HOA, the management company or the developer company, according to the approved design documentation, and is further serviced by qualified personnel.
The exterior of the building. Diverse, installed in different places And in a different way individual antennas spoil appearance building. Very often, the management company or the board of the HOA prohibit residents from installing any antennas on the outer walls. Yes, this is not always technically possible - for example, on a glass facade or on a wall covered with siding. It happens that all the windows of the apartment face the north side, where satellite dishes cannot work in principle. Of course, you can install individual antennas on the roof, but there is usually limited space. In addition, at least one cable must go down to the subscriber's apartment from each individual antenna. In modern residential buildings in one entrance there can be 100 or more apartments - not a single cable "riser" can accommodate such a number of cables. With a collective system, everything is simpler: there is always room for one or two dishes, and common, “backbone” cables in vertical cable channels will need to be laid from 1 to 9 (depending on the chosen technology and the number of received satellites) - this is already quite real.
No additional cables. The user of a personal antenna usually runs separate cables from their antennas. If the antenna is mounted outside the windows of the apartment, the outer wall must be drilled for cables. Cold air and dust enter through the hole from the outside, and if it is drilled illiterately, water can flow out of it during rain. In a collective system, a single cable enters the subscriber's apartment, through which signals of both satellite and conventional television are delivered. It is laid along the "regular" path - from a low-voltage floor shield on the landing. In the vast majority of cases, it is possible to connect an existing apartment wiring to a collective system, modifying it to a minimum, without laying new cables (only by replacing subscriber sockets and dividers). That is, to connect to the collective system in the apartment, you do not need to carry out "dirty" installation work and disrupt existing finishes.
Possibilities for modernization. Collective systems are easily scalable. For example, high-definition satellite channels can be added to a collective system for receiving conventional television and NTV-Plus (for example, the HD Platform package). To do this, it is enough to install one additional dish, and the channels from the added satellite will automatically become available to all subscribers of the system. This will not work with individual systems - an additional antenna will have to be installed at each subscriber. The collective system is easy to expand in terms of coverage. For example, if the system is mounted on one entrance of a residential building, you can connect other entrances to it by simply running cables through them. Modern technologies allow you to deliver signals from satellite dishes via fiber optic cables even to neighboring houses. This technology is especially relevant for summer cottages and cottage settlements. In such settlements, the buildings are low, and often the satellites are closed by a nearby forest. The collective system will make it possible to install one antenna post for the entire village and connect individual houses to it with “optics”. The same fiber optic cable can be used to connect TV, phones and high speed internet.

Collective antenna with common amplifier

The system is an analogue of the traditional "entrance antenna" system and consists of a set of terrestrial antennas, a special multi-input amplifier and a distribution network.

The antenna complex provides high-quality reception of urban TV programs. In modern cities, terrestrial television is broadcast in different frequency ranges and often from several different directions, so one all-wave antenna is usually not enough. For example, there are 20 television channels on the air of the city of Yekaterinburg, which are transmitted from three different TV towers in three frequency bands (MV-I, MV-III, UHF) and with different radiation polarization (horizontal and vertical). Therefore, for high-quality reception of all city programs in the city center, a complex of five terrestrial antennas is needed.

A multi-input amplifier (Multiband) is needed to correctly combine signals from antennas of different ranges. Television centers use transmitters of different power, and antennas of different ranges have unequal gain, as a result, the levels of television signals at the antenna outputs can differ significantly. For example, in the center of Yekaterinburg, the signal of Channel One in the meter range can be several thousand times stronger than the signals of the decimeter channels (by 30-40 dB). To distribute television signals from one antenna complex to many TVs, they must be amplified. But the signals of different television ranges need to be amplified in different ways, otherwise either channels with low levels will be too weak, "noisy" at the input of the TVs, or channels with high levels will overload the amplifier, which is even worse - "crosstalk" will appear on all channels. Multiband amplifiers have several inputs (usually from 3 to 5) for connecting antennas of different ranges, with separate gain control for each input. There are powerful Multiband amplifiers for a large number of subscribers (an apartment building, an entrance to a high-rise building) and relatively weak ones for small systems ( a private house or several neighboring apartments).

The distribution network consists of cables and dividers. Its purpose is to deliver signals from the output of the amplifier to subscribers' TVs. The output power of the amplifier should be distributed among all subscribers as equally as possible, only under this condition the amplifier is used as efficiently as possible, and the signal levels at all subscriber outlets are within acceptable limits. However, real distribution networks are usually built according to a "linear" scheme, where some subscribers are located near the amplifier, while others are far away. Therefore, two types of power dividers are used in the network - into equal parts (splitters, splitters) and into unequal parts (couplers, couplers).

Advantages:

The system is inexpensive, compact and easy to operate. If necessary, a more complex system can be built on its basis: an on-air SKPT with a head station or a system for the collective reception of on-air and satellite programs.

Flaws:

The system is only applicable to a large number subscribers (one entrance or a small apartment building, office, cottage). The Multiband amplifier allows you to separately adjust the gain by frequency ranges, but it cannot be used to equalize the levels of different channels within the same range. Therefore, the system works correctly only if the amplifier in it is the only one.

On-air SKPT with direct amplification head station.

This is a more complex system, in which the television signals of each channel are processed separately. The heart of the system is the direct amplification headend. This is a modular design, consisting of a base unit or chassis, on which channel amplifier modules are installed - one for each channel. Such a scheme allows you to equalize the levels of all television channels, "cut them one size fits all." Such a "trimmed" group signal can be distributed to a large number of subscribers, amplifying it many times if necessary.

Channel-by-channel processing allows you to eliminate problems with the reception of individual channels: additionally amplify weak ones, possibly attenuate too strong ones.

Advantages:

The system allows you to receive high-quality signals from all city TV channels on subscriber outlets, even under difficult reception conditions. SKPT with a head station can serve a large apartment building or even several houses, a microdistrict. It can be integrated with a collective satellite system, you can add your own channels to it - for example, distribute images from CCTV cameras to subscribers' TVs.

Flaws:

The cost of SKPT with a headend is somewhat higher than systems with a common amplifier. A separate channel amplifier module is required for each television channel, so if new channels appear in the city, the headend must be upgraded.

Systems of collective reception of terrestrial and satellite programs (SMATV)

All collective satellite systems offered by us assume simultaneous reception of satellite and terrestrial (conventional) TV programs. Satellite and terrestrial television signals are delivered to subscribers' apartments via a single cable. To simultaneously connect a TV and a satellite receiver, special subscriber sockets with two separate outputs (TV / SAT) or external separator filters are used.

Matrix systems (Star Distribution)

These collective satellite systems have the maximum capabilities and are the most convenient in operation. However, they are the most expensive and rather bulky, therefore they are used mainly for a small number of subscribers - with rare exceptions, for one residential or office building.

They are based on matrix antenna switches - multiswitches. In general, the multiswitch has several inputs for connecting satellite dishes (usually 4, 8 or 16), one input for connecting a conventional television antenna (or local cable TV signal) and several subscriber outputs (usually 4, 6, 8, 10, 12 or 16). Depending on the control signal coming from the subscriber's receiver, the subscriber's output is connected to one or another satellite input. The signal of conventional television is always present at all subscriber outputs. Thus, each subscriber gets access to any channels from all satellite dishes in the system, regardless of other subscribers.

Due to some technical reasons, in order to connect one satellite dish to the matrix system, it is sometimes necessary to use not one, but several satellite inputs: 2, 3 or 4. It depends on the selected satellite, more precisely, on the used frequency range and radiation polarization. For example, for the collective reception of NTV-Plus and Tricolor programs (Eutelsat W4 / W7 satellite), 2 satellite inputs must be used, for receiving popular European HotBird satellites - 4, and for receiving high-definition television (HD Platform package, etc. ) from the Eurobird-9 satellite, one entry is enough.

Matrix collective system for receiving programs of 4 satellites on 8 independent receivers (private house, cottage)

To increase the capacity of matrix systems, cascaded multiswitches are produced - in addition to subscriber outputs, they have "through" or "trunk" outputs, on which the input signals of satellite and conventional television are repeated. The next multiswitch is connected to these outputs - terminal or other cascaded. According to this scheme, matrix systems with a linear topology are built - for example, for one entrance of a multi-storey building.

"Linear" matrix system for receiving 3 satellites for 20 subscribers (one entrance)

Another scheme used for capacitance expansion is radial. Signals from a television antenna and satellite and antennas are divided using splitters and sent to several multiswitches. Such a scheme can be used, for example, in a matrix system with several entrances, if there are few floors in the house.

In larger systems, combinations of linear and radial circuits are used: signals from sources are divided radially and fed to the inputs of several linear chains of multiswitches connected in cascade.

"Linear-radial" matrix system for receiving NTV-Plus (Tricolor-TV) for 30 subscribers (residential building 3 entrances, 5 floors, 2 apartments per floor)

Multiswitches are active and passive. Passive ones simply divide the input signal between subscriber and trunk outputs, active ones also amplify it to compensate for power losses during division and attenuation of signals in cables. Manufacturers offer the widest range of multiswitches and auxiliary devices(multichannel amplifiers, multichannel couplers, power supplies, etc.), on the basis of which it is possible to build collective systems of varying complexity and size.

Advantages:

You can collectively receive signals from several satellites
The subscriber can receive any channels from all satellite dishes connected to the system
The system is "transparent" for the subscriber's receiver: setting up and using the receiver is exactly the same as if the subscriber used his own individual antenna (antennas)
Reception of paid satellite programs is carried out absolutely legally, as well as through individual systems

Flaws:

The system uses "multi-cable" backbone wiring. This complicates installation somewhat, especially in older buildings.
Quite expensive equipment

"Single-cable" collective systems

The "main" wiring of such collective systems is carried out with a single cable, and instead of expensive and complex matrix switches, compact and cheap dividers are used, so the system is inexpensive and easy to install. However, the capabilities of "single-cable" systems are severely limited.

Satellite television uses different frequency ranges and different polarizations of radio waves. In an individual receiving system, the choice of range and polarization takes place in the converter - the electronic "head" of the antenna, and signals from not all satellite channels, but only from one range and one polarization are received in the cable to the subscriber - exactly those that the subscriber needs at the moment. In a collective system, it is necessary to simultaneously receive all satellite signals. You can’t just put them together to feed them into one cable - they overlap in frequency and will interfere with each other.

"Single-cable" collective systems are built according to one of three schemes:

"One-cable" system without frequency multiplexing

The system allows you to collectively receive the programs of only one satellite, but not all, but only part of them - in one frequency range and with only one radiation polarization. A typical example is the popular satellite Yamal-201 90.0E, in which the most interesting TV channels are transmitted in the C-band with left-hand rotational polarization (LZ).

The satellite dish and converter are used as usual, as for individual reception. A satellite amplifier is needed to compensate for signal loss during division between subscribers and attenuation in cables. Ordinary television dividers will not work - they only work in the frequency range of ordinary television (5 ... 1000 MHz), but broadband ones are needed, with support for the satellite range (up to 2150 MHz).

An example of the simplest "single-cable" collective satellite system (reception of the "Continent-TV" package in one entrance)

Advantages:

The system is very simple and cheap.

Flaws:

Severely limited use. You can receive signals from only one satellite, for example:

Paid package "Rainbow-TV" from satellite ABS-1 75.0E
paid package"Continent-TV" from the satellite Intelsat-15 85.2E
paid package "Tricolor-TV" from satellite Eutelsat W4/W7 36.0E
paid package "Tricolor-Siberia" or "NTV-Plus-Vostok" from satellite Bonum-1 56.0E (but only one to choose from, not at the same time)
high-definition package "HD Platform" from satellite Eurobird-9 9.0Е

“Single cable” system with special converter Single Cable Solution

"Single-cable" system of collective reception "NTV-Plus" at the entrance using a frequency multiplexing device SUP-575

The system is not much more complex and expensive than sealless systems, but it does require "exotic" equipment. This is either a special converter with a built-in frequency multiplexing device for two signals of different polarization (Single Cable Solution), or external device seals.

Single Cable Solution systems are applicable only in some special cases, when all the necessary satellite channels are located at close frequencies. A typical example of use is the collective reception of NTV-Plus and Tricolor-TV packages from the Eutelsat W4 / W7 36.0E satellite or NTV-Plus-Vostok and Tricolor-Siberia from the Bonum-1 56.0E satellite.

Advantages:

The system is simple and cheap
the system can be easily integrated with the existing terrestrial "antenna to the entrance" system by replacing conventional signal splitters with broadband ones

Flaws:

Severely limited use - can only be used for collective reception of NTV-Plus and Tricolor-TV
the system is "not transparent" for subscriber receivers. The settings of the receiver for operation in a collective Single Solution system are different from the settings in an individual system. Automatic setting not supported, channels need to be "registered" manually

"Single-cable" system with satellite converter headend (IF-IF Processing)

"Single-cable" system with a station of satellite converters "IF to IF" for two entrances for receiving NTV-Plus, Tricolor-TV and Continent-TV

This is a more complex system that requires more expensive equipment, but it can be used to receive programs from different satellites (although the total number of channels is limited).

The distribution network remains exactly the same, with one "backbone" cable and broadband splitters. Between the distribution network and satellite antennas, a head station is installed - a set of converter modules, each of which processes the signal at one carrier frequency (one "transponder"). With their help, you can collect signals of different channels from different satellites operating in different frequency ranges and with different polarizations into one cable. Thus, the head station emulates one "virtual satellite", which contains all the programs of interest to the subscriber.

Advantages:

Flaws:

Requires fairly expensive headend equipment
the number of channels available to the subscriber is limited by the number of headend modules. If a new TV package has appeared on the satellite, then in order for it to become available, an additional module must be installed at the head station.
the system is "not transparent" for subscriber receivers. The settings of the receiver for operation in a collective system with an IF-IF Processing head station are different from the settings in an individual system. Automatic tuning is not supported, channels must be "registered" manually

Digital Cable TV (DVB-C)

In principle, this is the technology of cable television networks, but in a simplified version it is also successfully used in collective satellite systems. For example, if subscribers are at considerable distances from each other (cottage village), or if you need to organize the collective reception of satellite programs in an existing conventional cable network that is unsuitable for operation in the satellite range.

Satellite TV signals are input to the headend, which consists of transmodulator modules that convert digital satellite TV signals (DVB-S, DVB-S2) into digital cable TV signals (DVB-C). Cable digital channels are formed in the range of conventional television, on meter or decimeter waves, so they can be delivered to subscribers via classic cable networks, coaxial or optical-coaxial. In the television band, cable losses are much less than at satellite frequencies. This allows you to build very large collective systems, up to a microdistrict, a village, and even a city. True, to receive satellite programs, the subscriber needs a specific cable digital receiver - it is slightly different from satellite and costs a little more.

Advantages:

The system can be used for collective reception of programs from several different satellites.
the system can be used for collective reception of programs from several different satellites
it is possible to build extended systems with very big amount subscribers
the system can be easily integrated into the existing distribution network for conventional (terrestrial or cable) television. At the same time, the network itself does not require any alteration, even special subscriber sockets are not needed.

Flaws:

The number of channels available to the subscriber is limited by the number of headend modules. to watch satellite programs, the subscriber needs a special cable digital receiver

Cable television systems (CATV)

Traditionally, cable television systems are collective systems with a very large number of subscribers, from a large house to an entire city, and, as a rule, they are built not by end users, but by cable operators, not for their own needs, but to provide cable TV services to the population. Although, of course, there are exceptions.

The cable television system (SKTV, CATV) consists of three parts: signal sources, head station, distribution network.

Signal sources can be: terrestrial antennas (local city programs), satellite dishes (satellite programs), as well as your own TV studio, VCR, DVD player, computer, etc. (own programs).

The head station is a modular device that consists of a base unit (chassis) and a set of functional modules. Depending on the signal sources used, these can be modules of channel amplifiers or converters (terrestrial TV), satellite receivers (satellite TV), or modulators (signals from own sources). The headend receives TV program signals from different sources, in different frequency ranges (television, satellite, unmodulated audio / video signals) in different formats (analogue, digital) and converts them into standard analog broadcast television signals in the range of meter and decimeter waves. Thus, from the point of view of a SKTV subscriber, broadcast, satellite and operator's own programs are no different - an ordinary TV is enough to receive them.

The distribution network is a system of cables, amplifiers and dividers (tap and splitters). Its purpose is to deliver the headend signal to each subscriber outlet, while compensating for division and attenuation losses in cables and, if possible, maintaining signal quality. For many years, more or less large-scale SKTVs have been built using fiber optic cables, mainly using Fiber to the Building (FTTB) technology. Optical cables introduce hundreds of times less attenuation, have an almost ideal amplitude-frequency response, are not afraid of dampness, thunderstorms, induced industrial interference, and last several times longer than copper ones. The electrical signal from the headend output is converted into a luminous flux, amplified, if necessary, split by special optical dividers and delivered to every house connected to the SKTV. An optical receiver is installed in the house, it converts the optical signal back into an electrical one so that it can be fed to the inputs of conventional TVs. The house distribution network is built on conventional coaxial cables and dividers.

Advantages:

SKTV can cover a huge number of subscribers - a microdistrict, a village, a city
SKTV subscriber does not need any additional equipment, cable channels are received on a regular TV

Flaws:

The equipment of modern SKTV is complex and expensive, so the technology is applicable only for a relatively large number of subscribers (from several hundred)
the number of channels available to the subscriber is limited by the number of headend modules (usually no more than 50 ... 60)

Digital broadcasting in SCTV

Today, many cable operators not only provide traditional analog television, but offer several digital packages, including high-definition (HDTV) programming. It is possible to feed digital packets from satellites into the cable network using transmodulators. However, cable operators are hardly interested in rebroadcasting satellite channels without changes - after all, then subscribers will pay for watching pay TV to a satellite operator, and it will be profitable for cable operators to sell their own services.

Therefore, more sophisticated equipment is used in "digital" headends. Satellite signals are demodulated - converted into digital streams. Paid, coded programs received from satellites are decrypted - made open. Then, from different satellite channels, the cable operator forms its own digital packages, in accordance with its marketing strategy. The generated digital streams are again encoded - but this time by the cable operator's own coding system, which allows it to control subscribers' access to programs and collect fees for viewing. Then the digital streams are transferred to the frequencies of the meter and decimeter ranges and, together with the analog channels, are sent to the distribution network.

To watch analog channels, a subscriber needs a regular TV, and to receive digital programs, a digital cable receiver is needed, and, as a rule, a specific one with support for the coding system used by the cable operator. Usually cable operators sell these receivers to subscribers or rent them out.

SKTV technology is designed for a large coverage of subscribers - from several hundred to several thousand. The cable operator is forced to rely on the average solvency of the population. Therefore, there are no "purely digital" SCTV in our country (at least for now) and digital broadcasting is positioned as an additional service.

IP television systems (IPTV)

This is a completely new, but rapidly developing technology.

In IPTV systems, television programs are delivered to subscribers over computer networks using the Internet Protocol (IP). It is necessary to distinguish between Internet television (TV broadcasting on the Internet, online broadcasting) and IP television. Although, in principle, the same technology is used, these are essentially different services.

In the first case, broadcasting is carried out on the public Internet, without any restrictions on the territory, as a rule, free of charge. Accordingly, there are no guarantees of quality (as well as the very possibility of reception) - it all depends on how each specific “viewer” is connected to the Internet, what speed his connection implies and how reliable it is. A PC is used to watch TV programs. By and large, TV broadcasting on the Internet is one of the many Internet services.

The IP-TV system is being built specifically to provide pay-TV services to the population. Broadcasting is localized in cable

networks of one operator - as a rule, this is an Ethernet or ADSL network. This network uses various mechanisms to guarantee the quality of video delivery. To watch programs, a TV is used, which is connected to a computer network through a special prefix - IP-Set top box(IP STB).

IPTV systems are more than just community reception systems. There are a few fundamental differences IP television systems from any other SKPT:

Cable television networks use analog transport. Even DVB digital television programs are transmitted over the network as an analog RF signal. From the headend to the subscriber socket, the signal is subjected to multiple passive division and amplification, which inevitably leads to a decrease in its quality (an increase in the signal-to-noise ratio). IPTV systems use only digital signals, each active device of the distribution network provides signal regeneration (restoration). Therefore, in IPTV systems, it is possible to deliver television programs to any number of subscribers at any distance, while maintaining the original image and sound quality.
In "classic" cable networks, each subscriber socket simultaneously contains the signals of all TV programs that are broadcast in the system. Therefore, the number of TV channels (and other services) is limited by the network bandwidth. In IPTV, the subscriber socket receives a signal of only one TV program - the one that the subscriber is watching at the moment. That's why throughput network section is determined not by the number of available services, but by the number of subscribers connected to this section. As a result, with proper network structuring, the number of available services of IPTV systems is practically unlimited.
IPTV initially uses a bidirectional symmetrical communication channel as a transport - computer network. This makes it easy to implement interactive services. Those. services, the content of which can be directly influenced by the subscriber himself: first of all, “on demand” services, as well as managing his subscription, “online” purchases, electronic voting, sweepstakes, network games, email and Internet access (without a computer, using a TV and STB).
All smart devices of "classic" cable networks (for example, satellite receivers of the headend or subscriber cable digital receivers) are electronic machines that work according to a rigid program. In IPTV systems, both the head equipment and the subscriber Set-Top-Box are computers running "normal" operating systems. All IPTV functionality is implemented programmatically. The same hardware platform allows the developer, and even more so - the user, to invent, write and implement software for a variety of services. In other words, IPTV is an "open" system, it can implement any services that can be implemented on the Internet, with the difference that in the IPTV system they will be provided with guaranteed quality.

The IPTV headend usually includes:

Streamers. These are devices that provide "online" services - television and radio reception. They convert the signals of television channels (satellite, terrestrial or from their own sources, digital or analog) into IP packets, which are then broadcast to the network using the multicast method.
On-demand service servers. They provide "offline" services. Movies and music are stored on disk drives of servers. Each subscriber can play a movie or a song of his choice on his TV at any time. In this case, the server at the headend acts as a remote DVD player. Packets are transmitted to the network to one specific subscriber using the unicast method.
"Delayed viewing" servers allow not only playback, but also recording of "online" content, that is, they perform the functions of a remote video recorder. The subscriber can program a recording of a program of interest to him and watch it at any convenient time. Even more interesting is the “watch from the beginning” service: the server records all the programs of a certain TV channel and stores the archive for some time, say, three hours. If the subscriber turned on this channel in the middle of the transmission, he can start watching from its beginning, with a time shift.
Conditional Access System (CAS) allows only authorized subscribers to view paid content
Client self-service system - Middleware. In fact, this is a program whose main task is to create an intuitive client interface on TV screens, a menu system with which the subscriber selects the service he needs and controls the viewing.

The functions of the distribution network in IPTV systems are performed by a computer data transmission network (DTN). As a rule, the same SPD is used simultaneously for IPTV, for Internet access and for telephony. Roughly speaking, one "twisted pair" comes to the subscriber's apartment. Services are separated not physically, but logically (for example, using the VLAN mechanism).

The subscriber device of the IPTV system is a TV and STB, which actually turn into a home multimedia center: they simultaneously perform the functions of a regular TV, media player (network analogue of a VCR or DVD player / recorder), game console and computer for Internet access.

Modern IP STBs support high-definition television (HDTV) and can connect to HDTVs via digital interface HDMI. STB has "on board" a high-performance processor and a semiconductor " HDD» with a volume of several GB. This allows you to implement a significant part of the IPTV functionality directly in the set-top box, by means of its software, without once again contacting the servers of the headend and without loading the network with unnecessary traffic. Thanks to this opportunity, it was possible to get rid of the main drawback early systems IPTV - "slow" response to user commands.

So far, IPTV systems are not widespread, mainly due to the relatively high cost of STB - from $150 for regular definition television and from $200 for high-definition television. As a rule, IP TV is offered by existing Internet service providers as an additional service.

Source -

For many years we have been designing and building collective television reception systems (CCTS). They are very different, both in size and purpose: from a collective antenna for two or three apartments to a cable network for the city, from a direct amplification terrestrial system to a matrix satellite system. Recently, systems of interactive IP-television are becoming more and more popular. Previously, this was a very expensive solution that only large telecom operators and Internet providers could afford. Now it is possible to build a fully functional IPTV network for a residential complex or hotel, at a cost comparable to a high-quality analog SKPT.

Why is a collective system better than an individual one?

Price. The price of a collective system in terms of one subscriber is less than the price of an individual system with the same capabilities. This is natural, since part of the equipment is used by all subscribers jointly and is bought “share”.
Quality. Reception of television in a modern city is not such an easy task. In general, high-quality reception requires serious equipment, which is too expensive for one user. Residents of an apartment building can afford to install good equipment and pay for quality installation.
Service. Maintaining an individual system in working condition is the concern of its owner only. Such systems are either not serviced at all, or each tenant has his own "master" who monitors only "his" system. As a result, several systems coexist in one house, built by different companies, on different equipment and at different times. As a rule, there is no documentation and marking. Each "master", having come to the house for the first time, is forced to deal with a hodgepodge of cables in low-voltage shields. The collective system is mounted by order of the HOA, the management company or the developer company, according to the approved design documentation, and is further serviced by qualified personnel.
The exterior of the building. Different-sized, installed in different places and in different ways, individual antennas spoil the appearance of the building. Very often, the management company or the board of the HOA prohibit residents from installing any antennas on the outer walls. Yes, this is not always technically possible - for example, on a glass facade or on a wall covered with siding. It happens that all the windows of the apartment face the north side, where satellite dishes cannot work in principle. Of course, you can install individual antennas on the roof, but there is usually limited space. In addition, at least one cable must go down to the subscriber's apartment from each individual antenna. In modern residential buildings in one entrance there can be 100 or more apartments - not a single cable "riser" can accommodate such a number of cables. With a collective system, everything is simpler: there is always room for one or two dishes, and common, “backbone” cables in vertical cable channels will need to be laid from 1 to 9 (depending on the chosen technology and the number of received satellites) - this is already quite real.
No additional cables. The user of a personal antenna usually runs separate cables from their antennas. If the antenna is mounted outside the windows of the apartment, the outer wall must be drilled for cables. Cold air and dust enter through the hole from the outside, and if it is drilled illiterately, water can flow out of it during rain. In a collective system, a single cable enters the subscriber's apartment, through which signals of both satellite and conventional television are delivered. It is laid along the "regular" path - from a low-voltage floor shield on the landing. In the vast majority of cases, it is possible to connect an existing apartment wiring to a collective system, modifying it to a minimum, without laying new cables (only by replacing subscriber sockets and dividers). That is, to connect to the collective system in the apartment, it is not necessary to carry out “dirty” installation work and violate the existing finish.
Possibilities for modernization. Collective systems are easily scalable. For example, high-definition satellite channels can be added to a collective system for receiving conventional television and NTV Plus (for example, the HD Platform package). To do this, it is enough to install one additional dish, and the channels from the added satellite will automatically become available to all subscribers of the system. This will not work with individual systems - an additional antenna will have to be installed at each subscriber. The collective system is easy to expand in terms of coverage. For example, if the system is mounted on one entrance of a residential building, you can connect other entrances to it by simply running cables through them. Modern technologies make it possible to deliver signals from satellite dishes via fiber optic cables even to neighboring houses. This technology is especially relevant for summer cottages and cottage settlements. In such settlements, the buildings are low, and often the satellites are closed by a nearby forest. The collective system will make it possible to install one antenna post for the entire village and connect individual houses to it with “optics”. The same fiber optic cable can be used to connect TV, phones and high speed internet.

Systems of collective reception of on-air programs (MATV)

Collective antenna with common amplifier

The system is an analogue of the traditional "entrance antenna" system and consists of a set of terrestrial antennas, a special multi-input amplifier and a distribution network.

A multi-input amplifier (Multiband) is needed to correctly combine signals from antennas of different ranges. Television centers use transmitters of different power, and antennas of different ranges have unequal gain, as a result, the levels of television signals at the antenna outputs can differ significantly. For example, in the center of Yekaterinburg, the signal of Channel One in the meter range can be several thousand times stronger than the signals of the decimeter channels (by 30-40 dB). To distribute television signals from one antenna complex to many TVs, they must be amplified. But the signals of different television ranges need to be amplified in different ways, otherwise either channels with low levels will be too weak, "noisy" at the input of the TVs, or channels with high levels will overload the amplifier, which is even worse - "crosstalk" will appear on all channels. Multiband amplifiers have several inputs (usually from 3 to 5) for connecting antennas of different ranges, with separate gain control for each input. There are powerful Multiband amplifiers for a large number of subscribers (an apartment building, an entrance to a high-rise building) and relatively weak ones for small systems (a private house or several neighboring apartments).

Advantages:

The system is inexpensive, compact and easy to operate. If necessary, a more complex system can be built on its basis: an on-air SKPT with a head station or a system for the collective reception of on-air and satellite programs.

Flaws:

the system is applicable only for a small number of subscribers (one entrance or a small apartment building, office, cottage). The Multiband amplifier allows you to separately adjust the gain by frequency ranges, but it cannot be used to equalize the levels of different channels within the same range. Therefore, the system works correctly only if the amplifier in it is the only one.

On-air SKPT with direct amplification head station.

Channel-by-channel processing allows you to eliminate problems with the reception of individual channels: additionally amplify weak ones, possibly attenuate too strong ones.

Advantages:

the system allows you to receive high-quality signals from all city TV channels on subscriber sockets, even under difficult reception conditions. SKPT with a head station can serve a large apartment building or even several houses, a microdistrict. It can be integrated with a collective satellite system, you can add your own channels to it - for example, distribute images from CCTV cameras to subscribers' TVs.

Flaws:

the cost of SKPT with a headend is somewhat higher than systems with a common amplifier. A separate channel amplifier module is required for each television channel, so if new channels appear in the city, the headend must be upgraded.

Systems of collective reception of terrestrial and satellite programs (SMATV)

Matrix systems (Star Distribution)

Due to some technical reasons, in order to connect one satellite dish to the matrix system, it is sometimes necessary to use not one, but several satellite inputs: 2, 3 or 4. It depends on the selected satellite, more precisely, on the used frequency range and radiation polarization. For example, for the collective reception of NTV Plus and Tricolor programs (Eutelsat W4 / W7 satellite), 2 satellite inputs must be used, for receiving popular European HotBird satellites - 4, and for receiving high-definition television (HD Platform package, etc.) from the Eurobird-9 satellite, one entry is enough.

"Linear" matrix system for receiving 3 satellites for 20 subscribers (one entrance)

In larger systems, combinations of linear and radial circuits are used: signals from sources are divided radially and fed to the inputs of several linear chains of multiswitches connected in cascade.

"Linear-radial" matrix system for receiving NTV Plus (Tricolor-TV) for 30 subscribers (residential building 3 entrances, 5 floors, 2 apartments per floor)

Multiswitches are active and passive. Passive ones simply divide the input signal between subscriber and trunk outputs, active ones also amplify it to compensate for power losses during division and attenuation of signals in cables. Manufacturers offer the widest range of multiswitches and auxiliary devices (multichannel amplifiers, multichannel couplers, power supplies, etc.), on the basis of which collective systems of varying complexity and size can be built.

Advantages:

You can collectively receive signals from several satellites
The subscriber can receive any channels from all satellite dishes connected to the system
The system is "transparent" for the subscriber's receiver: setting up and using the receiver is exactly the same as if the subscriber used his own individual antenna (antennas)
Reception of paid satellite programs is carried out absolutely legally, as well as through individual systems

Flaws:

The system uses "multi-cable" backbone wiring. This complicates installation somewhat, especially in older buildings.
Quite expensive equipment

"Single-cable" collective systems

"Single-cable" collective systems are built according to one of three schemes:

"One-cable" system without frequency multiplexing

An example of the simplest "single-cable" collective satellite system (reception of the "Continent-TV" package in one entrance)

Advantages:

the system is very simple and cheap

Flaws:

very limited application. You can receive signals from only one satellite, for example:

paid package "Rainbow-TV" from satellite ABS-1 75.0E
paid package "Continent-TV" from satellite Intelsat-15 85.2E
paid package "Tricolor-TV" from satellite Eutelsat W4/W7 36.0E
paid package "Tricolor-Siberia" or "NTV Plus-Vostok" from satellite Bonum-1 56.0E (but only one to choose from, not at the same time)
high-definition package "HD Platform" from satellite Eurobird-9 9.0Е

“Single cable” system with special converter Single Cable Solution

"Single-cable" system of collective reception "NTV Plus" at the entrance using a frequency multiplexing device SUP-575

The system is not much more complex and expensive than sealless systems, but it does require "exotic" equipment. This is either a special converter with a built-in frequency multiplexer for two signals of different polarization (Single Cable Solution), or an external multiplexer.

Single Cable Solution systems are applicable only in some special cases, when all the necessary satellite channels are located at close frequencies. A typical example of use is the collective reception of NTV Plus and Tricolor-TV packages from the Eutelsat W4 / W7 36.0E satellite or NTV Plus-Vostok and Tricolor-Siberia from the Bonum-1 56.0E satellite.

Advantages:

system is simple and cheap
the system can be easily integrated with the existing terrestrial "antenna to the entrance" system by replacing conventional signal splitters with broadband ones

Flaws:

very limited use - can only be used for the collective reception of "NTV Plus" and "Tricolor-TV"
the system is "not transparent" for subscriber receivers. The settings of the receiver for operation in a collective Single Solution system are different from the settings in an individual system. Automatic tuning is not supported, channels must be "registered" manually

"Single-cable" system with satellite converter headend (IF-IF Processing)

"Single-cable" system with a station of satellite converters "IF to IF" for two entrances for receiving NTV Plus, Tricolor-TV and Continent-TV

This is a more complex system that requires more expensive equipment, but it can be used to receive programs from different satellites (although the total number of channels is limited).

Advantages:

Flaws:

rather expensive headend equipment required
the number of channels available to the subscriber is limited by the number of headend modules. If a new TV package has appeared on the satellite, then in order for it to become available, an additional module must be installed at the head station.
the system is "not transparent" for subscriber receivers. The settings of the receiver for operation in a collective system with an IF-IF Processing head station are different from the settings in an individual system. Automatic tuning is not supported, channels must be "registered" manually

Advantages:

the system can be used for collective reception of programs from several different satellites
the system can be used for collective reception of programs from several different satellites
it is possible to build extended systems with a very large number of subscribers
the system can be easily integrated into the existing distribution network for conventional (terrestrial or cable) television. At the same time, the network itself does not require any alteration, even special subscriber sockets are not needed.

Flaws:

the number of channels available to the subscriber is limited by the number of headend modules. to watch satellite programs, the subscriber needs a special cable digital receiver

Cable television systems (CATV)

The cable television system (SKTV, CATV) consists of three parts: signal sources, head station, distribution network.

Signal sources can be: terrestrial antennas (local city programs), satellite dishes (satellite programs), as well as your own TV studio, VCR, DVD player, computer, etc. (own programs).

Advantages:

SKTV can cover a huge number of subscribers - a microdistrict, a village, a city
SKTV subscriber does not need any additional equipment, cable channels are received on a regular TV

Flaws:

modern SKTV equipment is complex and expensive, so the technology is applicable only for a relatively large number of subscribers (from several hundred)
the number of channels available to the subscriber is limited by the number of headend modules (usually no more than 50 ... 60)

Digital broadcasting in SCTV

Today, many cable operators not only provide traditional analogue television services, but also offer several digital packages, including high-definition TV (HDTV) programming. It is possible to feed digital packets from satellites into the cable network using transmodulators. However, cable operators are hardly interested in rebroadcasting satellite channels without changes - after all, then subscribers will pay for watching pay TV to a satellite operator, and it will be profitable for cable operators to sell their own services.

IP television systems (IPTV)

This is a completely new, but rapidly developing technology.

The IP-TV system is being built specifically to provide pay-TV services to the population. Broadcasting is localized in cable

IPTV systems are more than just community reception systems. There are several fundamental differences between IP television systems and any other SKPT:

Cable television networks use analog transport. Even DVB digital television programs are transmitted over the network as an analog RF signal. From the headend to the subscriber socket, the signal is subjected to multiple passive division and amplification, which inevitably leads to a decrease in its quality (an increase in the signal-to-noise ratio). IPTV systems use only digital signals, each active device of the distribution network provides signal regeneration (recovery). Therefore, in IPTV systems, it is possible to deliver television programs to any number of subscribers at any distance, while maintaining the original image and sound quality.
In "classic" cable networks, each subscriber socket simultaneously contains the signals of all TV programs that are broadcast in the system. Therefore, the number of TV channels (and other services) is limited by the network bandwidth. In IPTV, the subscriber socket receives a signal of only one TV program - the one that the subscriber is watching at the moment. Therefore, the bandwidth of a network section is determined not by the number of available services, but by the number of subscribers connected to this section. As a result, with proper network structuring, the number of available services of IPTV systems is practically unlimited.
In IPTV, a bidirectional symmetrical communication channel - a computer network - is initially used as a transport. This makes it easy to implement interactive services. Those. services, the content of which can be directly influenced by the subscriber himself: first of all, “on demand” services, as well as the management of his subscription, “online” purchases, electronic voting, sweepstakes, network games, e-mail and Internet access (without a computer, with TV and STB).
All intelligent devices of "classic" cable networks (for example, satellite receivers of the head station or subscriber digital cable receivers) are electronic machines that work according to a rigid program. In IPTV systems, both the head equipment and the subscriber Set-Top-Box are computers running "normal" operating systems. All IPTV functionality is implemented programmatically. The same hardware platform allows the developer, and even more so - the user, to invent, write and implement software for a variety of services. In other words, IPTV is an "open" system, it can implement any services that can be implemented on the Internet, with the difference that in the IPTV system they will be provided with guaranteed quality.

The IPTV headend usually includes:

Streamers. These are devices that provide "online" services - television and radio reception. They convert the signals of television channels (satellite, terrestrial or from their own sources, digital or analog) into IP packets, which are then broadcast to the network using the multicast method.
On-demand service servers. They provide "offline" services. Movies and music are stored on disk drives of servers. Each subscriber can play a movie or a song of his choice on his TV at any time. In this case, the server at the headend acts as a remote DVD player. Packets are transmitted to the network to one specific subscriber using the unicast method.
"Delayed viewing" servers allow not only playback, but also recording of "online" content, that is, they perform the functions of a remote video recorder. The subscriber can program a recording of a program of interest to him and watch it at any convenient time. Even more interesting is the “watch from the beginning” service: the server records all the programs of a certain TV channel and stores the archive for some time, say, three hours. If the subscriber turned on this channel in the middle of the transmission, he can start watching from its beginning, with a time shift.
Conditional Access System (CAS) allows only authorized subscribers to view paid content
Client self-service system - Middleware. In fact, this is a program whose main task is to create an intuitive client interface on TV screens, a menu system with which the subscriber selects the service he needs and controls the viewing.

Modern IP STBs support high-definition television (HDTV) and can connect to HD TVs via a digital HDMI interface. STB has a high-performance processor and a semiconductor "hard disk" with a capacity of several GB on board. This allows you to implement a significant part of the IPTV functionality directly in the set-top box, using its software, without once again contacting the headend servers and without loading the network with unnecessary traffic. Thanks to this possibility, it was possible to get rid of the main drawback of early IPTV systems - a “slow” response to user commands.

http://www.satcomservice.ru/kols.html#s321

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