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SMATV (SATELLITE MASTER ANTENNA TELEVISION) SYSTEMS
GUIDELINES FOR DESIGN OFFICES, INVESTORS, INSTALLERS
Our intention in creating this document was to inform prospective investors, project offices and installation companies on the issues connected with (S)MATV / shared antenna systems, in particular, their modernization and adaptation to the requirements of DVB-T.
The upgrading plans may also include distribution of satellite signals, both FTA and from pay-TV platforms. In the second part of the study we'll show the principles of planning this type of installations and proven solutions proposed by TERRA.
Amplifiers
Amplifier sets operating in MATV systems can be divided into two general categories:
- broadband amplifiers used in smaller systems (usually up to about 50 outlets),
- channel amplifiers used in small, medium, and large systems.
In the first case, the introduction of digital broadcasts should not pose any problem. It works somehow "automatically", and the only thing the system administrator should do is to test whether the gain of the amplifier(s) is adequate for the new signals (taking into consideration the signal levels in all outlets).
Generally, the signal levels of DVB-T multiplexes should be 6-10 dB lower in relation to the levels of video carriers of analog TV signals. More about the measurements and parameters of digital signals and the requirements for this type of installation can be read in the article Measurements and amplification of DTT (DVB-T) signals.
Generally, the signal levels of DVB-T multiplexes should be 6-10 dB lower in relation to the levels of video carriers of analog TV signals. More about the measurements and parameters of digital signals and the requirements for this type of installation can be read in the article Measurements and amplification of DTT (DVB-T) signals.
In the case of channel amplifiers the situation is quite different. The maintenance person is required to make changes in the system. Many existing systems are based on sets of Alcad channel amplifiers. Since 2003, the amplifiers have been installed in thousands of MATV systems.
The number of the channel amplifiers is equal to the number of received and distributed channels. The amplifier characteristics (linearity in the the entire width of the channel) makes these amplifiers suitable both for receiving analog TV channels and DVB-T multiplexes.
As a rule, the sets for analog TV contain power supply and 5-7 channel amplifiers (modules). As the mounting frame can hold up to 12 modules, the modernization of the set consists in adding next amplifiers, one module for one digital multiplex.
As a rule, the sets for analog TV contain power supply and 5-7 channel amplifiers (modules). As the mounting frame can hold up to 12 modules, the modernization of the set consists in adding next amplifiers, one module for one digital multiplex.
Investors and contractors facing the choice of amplifiers for digital terrestrial television can now use a new generation of channel amplifiers - digitally tuned channel amplifiers TERRA at420 R82510.
These amplifiers are ideal for every MATV system:
These amplifiers are ideal for every MATV system:
- apartment houses, multi-dwelling units,
- hotels and boardinghouses,
- hospitals, nursing homes, public buildings.
The main advantages of the TERRA at420 amplifiers:
- perfectly working with analog and digital signals,
- digitally tuned, with SAW filters ensuring high selectivity,
- one unit amplifies two analog TV channels or two DVB-T multiplexes freely chosen within UHF band,
- AGC - automatic equalization of all channel levels to 85 dBuV (analog mode) or 80 dBuV (DVB-T mode),
- 12 VDC / 0.1 A power for preamplifiers,
- DIN rail mounting (usually in a 19" RACK cabinet).
Terra also provides other components for a new-generation of MATV systems. A universal system consists of:
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Twin, digitally tuned channel amplifier with AGC, optimized for DVB-T - Terra at420 R82510
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Multiband Amplifier Terra ma400 (FM/VHF/UHF) R82520 - is used to increase the levels of signals coming from all at420 amplifiers and from RF modulators, as well as to combine VHF and FM signals.
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Twin VSB multi-standard modulator Terra mt420 (ch. 6-12, 21-69, S1-S40) R82515
DIN rail RACK mounting bracket for up to 8 modules - R82538.
DIN rail power supply DR-60-12 (12 VDC / 4.5 A) - R82532
DC distribution cable 699.20 R82536
F-F coaxial bridge 699.026 R82540
An example set of the Terra amplifiers and modulators for a MATV system.
The components of the set:
- four twin modulators mt420 R82515 allowing for introduction of 8 channels from external video sources (CCTV cameras, media players, DVD players, satellite receivers, etc.),
- three twin channel amplifiers at420 R82510 for amplifying 6 DVB-T multiplexes or analog TV channels,
- multiband amplifier ma400 R82520 combining and equalizing UHF, VHF and FM signals - the maximum output level (DIN45004B) of 118 dBuV is sufficient for distributing the signals to over 200 outlets, without using additional amplifiers.
Application of TERRA amplifiers enables smooth transition from analog to digital TV over the period of starting DVB-T transmitters and subsequent switching off analog TV channels. The changes in broadcast parameters of digital transmitters, including channel shifts of the multiplexes, will not require any hardware modifications. The intervention will be limited to re-tuning a particular channel amplifier to the new channel. It is performed by the buttons on the front panel of the module and takes a minute or so, and does not require any additional equipment.
In the case of installations currently operating within the whole frequency spectrum (not using channel converters shifting UHF channels to lower ones), the necessary adaptation to DVB-T multiplexes will require only some changes in active equipment (adjusting broadband amplifiers or exchanging/retuning/adding channel amplifiers).
Systems with older or low-quality cabling may require an exchange, a least in some fragments. Over time, the old or poor quality cables lose their initial parameters and show both increased attenuation and lower screening efficiency. In the case of analog television these flaws may cause only fine snowing and occasional interferences, whereas digital broadcasts can be pixelated or frozen.
Newly designed systems should absolutely use reputable brands of coaxial cables with screening efficiency at least at the "Class A" level.
Systems with older or low-quality cabling may require an exchange, a least in some fragments. Over time, the old or poor quality cables lose their initial parameters and show both increased attenuation and lower screening efficiency. In the case of analog television these flaws may cause only fine snowing and occasional interferences, whereas digital broadcasts can be pixelated or frozen.
Newly designed systems should absolutely use reputable brands of coaxial cables with screening efficiency at least at the "Class A" level.
![Coaxial Cable (75 ohm): TRISET-113 1.13/4.8/6.8 [1m]](https://static.dipol.com.pl/images/en/pict/e1015_1_.gif)
![Coaxial Cable (75 ohm): TRISET PROFI 120dB A++ 1.13/4.80/6.90 [100m]](https://static.dipol.com.pl/images/en/pict/e1010_100_.gif)
It happens that the investor gives the installer a free hand in selecting the cable. The investor shouldn't seek cost savings by using cheap cables produced for other purposes than the distribution of television (e.g. RG-59). The difference in signal attenuation over a distance of 100 m at 860 MHz for this type of cable and TRISET-113 is about 18 dB! It means three times lower signal at the end of the cable length. As mentioned above, what snows a little an analog channel, may block reception of a digital multiplex.
In most cases, the antenna array responsible for the current reception of analog channels will be suitable for receiving digital TV signals. Due to technical compatibility, replacement of antennas is not necessary, unless some digital multiplex is broadcast on a very high channel not properly received by the existing UHF antenna. Of course, the prerequisite for proper reception is good condition of the antenna array, so it is necessary to replace corroded or incomplete antennas or/and mounts. Because of "digital cliff", signal instability caused by poor technical condition of antenna system is more "dangerous" than in case of analog TV.
Dipol Tri-Digit A2670 antenna
The initial power of DVB-T transmitters may be low due to the transitional period (simultaneous transmission of analog and digital signals) which can last up to several years. In such cases, the DVB-T reception can be improved by replacing the antenna with a model having a higher energetic gain.
The type of antenna for MATV systems preferred by installers is Tri-Digit A2670. It combines two important features:
The type of antenna for MATV systems preferred by installers is Tri-Digit A2670. It combines two important features:
- high energetic gain (18 dBi at the upper limit of the UHF band) ensuring good signal level at the input of the antenna system,
- compact design and small dimensions, which is important also in the case of antennas mounted on roofs of even large buildings - other types of antennas having similar gain are 2-3 m long and much more susceptible to defects associated with external factors (wind, birds), their delicate "X" directors can easily become deformed.
Other receiving antennas
Some installers "modernizing" antenna arrays eliminate VHF (BIII) antennas, claiming that DVB-T multiplexes are to be broadcast only in UHF band channels (channels 21-69). This opinion is very popular, but does not take into consideration other aspects.
The VHF band III which is in some countries still used for broadcasting analog television channels (till the end of transitional period), will be used in the future for T-DAB transmissions (Terrestrial Digital Audio Broadcasting which is to replace the existing FM radio services).
The 174-230 MHz band will be divided into 8 channels with width of 7 MHz (instead of the current 7 channels with width of 8 MHz). Each of them will contain four "sub-channels" dedicated to broadcasting digital radio programs. As a result, the band will accommodate 32 digital radio programs broadcast in T-DAB standard.
But this is not the only reason why antenna installers should refrain from VHF III antennas. In some countries one of these channels may be used for an additional DVB-T multiplex. So, it is good to be prepared for such an eventuality.
The VHF band III which is in some countries still used for broadcasting analog television channels (till the end of transitional period), will be used in the future for T-DAB transmissions (Terrestrial Digital Audio Broadcasting which is to replace the existing FM radio services).
The 174-230 MHz band will be divided into 8 channels with width of 7 MHz (instead of the current 7 channels with width of 8 MHz). Each of them will contain four "sub-channels" dedicated to broadcasting digital radio programs. As a result, the band will accommodate 32 digital radio programs broadcast in T-DAB standard.
But this is not the only reason why antenna installers should refrain from VHF III antennas. In some countries one of these channels may be used for an additional DVB-T multiplex. So, it is good to be prepared for such an eventuality.
T-DAB / DVB-T channels in VHF III band
[source: mi.gov.pl]
All installations distributing TV channels only in the VHF band should be modernized to provide the ability to distribute television programming also in the UHF band.
Any attempts to postpone the modernization of such installations involving the application of successive UHF/VHF channel converters should be considered as a temporary solution. The main reason is the mentioned earlier ultimate use of the VHF band for other digital services. Another issue is the limitation of the bit rates of digital multiplexes in the VHF band due to narrower channels.
Any attempts to postpone the modernization of such installations involving the application of successive UHF/VHF channel converters should be considered as a temporary solution. The main reason is the mentioned earlier ultimate use of the VHF band for other digital services. Another issue is the limitation of the bit rates of digital multiplexes in the VHF band due to narrower channels.
DVB-T signal regeneration is possible when a single receiver connected directly to the antenna allows a relatively trouble-free reception of digital broadcasts. After regeneration, the signal can be amplified and distributed to tens or even hundreds of outlets. The input threshold parameters usually sufficient for satisfactory reception/regeneration of the signal are: MER of 26 dB, BER of 0.001.
In such situations it is essential to use antennas with the highest possible energetic gain, such as Tri-Digit A2670. In combination with Terra ttx311 COFDM/COFDM transmodulator (available on request), which demodulates the multiplex to the transport stream, corrects signal errors (if it is technically possible), and modulates again as COFDM RF channel - the antenna system may provide satisfactory results even in difficult environments.
In such situations it is essential to use antennas with the highest possible energetic gain, such as Tri-Digit A2670. In combination with Terra ttx311 COFDM/COFDM transmodulator (available on request), which demodulates the multiplex to the transport stream, corrects signal errors (if it is technically possible), and modulates again as COFDM RF channel - the antenna system may provide satisfactory results even in difficult environments.
COFDM-COFDM transmodulator TERRA ttx311. The module is installed in the UC-380 base unit R81700 which can house up to 8 units (including other types).
One ttx311 module is responsible for transmodulation (regeneration) of one DVB-T multiplex.
One ttx311 module is responsible for transmodulation (regeneration) of one DVB-T multiplex.
The idea of using the ttx311 regenerator
An additional advantage of the device is the possibility of modifying transport stream, very useful in hotels, hospitals, correctional facilities etc. The service filtering option allows for cutting out some channels from the DVB-T multiplex.
Such facilities equipped with obsolete CRT televisions or newer ones not compatible with the ultimate standard (e.g. MPEG-4) used in the country, make a separate category. Due to obvious reasons, the TV sets cannot receive digital terrestrial TV programs.
Investors facing the need of modernization of the antenna systems can choose one of three solutions, each of which has both advantages and disadvantages. In every case, the most appropriate solution depends on the number of outlets, available budget and individual preferences of the investor.
Investors facing the need of modernization of the antenna systems can choose one of three solutions, each of which has both advantages and disadvantages. In every case, the most appropriate solution depends on the number of outlets, available budget and individual preferences of the investor.
- 1. Purchasing new televisions equipped with built-in tuners compatible with the required standard (e.g. MPEG-4). It requires the largest financial outlays that are primarily dependent on the screen size and quality of the selected model. However, it will ensure the reception of DVB-T broadcast in SD and HD quality with the use of the single remote control supplied with each TV set.
- 2. Supplying each television with external DVB-T receiver (set-top-box - STB) etc. Depending on the TV, the STB should provide only SD video (for CRT televisions and low-resolution LCDs), or be able to transfer HD channels (in the case of HD and HD-Ready TVs). The disadvantage of this solution is the necessity of using two remote control units, for the TV and DVB-T receiver.
DVB-T receiver and media player Signal HD-527 A99252 (MPEG-2/4, PVR Ready)
However, this solution provides additional functions:
- PVR Ready - recording selected programs on external USB memory device,
- EPG - Electronic Program Guide; EPG recording enables recording of programs chosen from the guide,
- Timeshift - possibility of pausing, delaying, then accelerating the watched program,
- Multi-page teletext loaded at the first start of the receiver,
- Selection of the language version of the subtitles,
- Selection of audio track,
- Parental Lock - possibility of entering the age of the (youngest) child and password in the menu. Each program with a higher age rating will require to provide the password.
The above solutions - buying new televisions or additional DVB-T receivers for all TV sets - are economically justified when the number of the existing televisions is not high (several to about 30).
- 3. Application of TERRA headends - in the case of a larger number of TV sets (>30), in many hotels, boardinghouses, jails - it is usually not possible to replace all the TVs at once or equip them with external DVB-T receivers. The owners or administrators want to spread it out over a longer time. The perfect solution for such facilities is the application of TERRA headends that demodulate COFDM digital signals and use them to generate analog PAL channels distributed in the antenna systems, which can be directly received by the older televisions. In parallel, the digital multiplexes are available for the newer televisions which are successively installed in these facilities.
The solution presented below based on TERRA equipment allows old televisions to access the full range of programs broadcast in DVB-T multiplexes.
The idea behind the solution is the installation of MMH-3000 headend in the central point of the signal distribution system. The headend is equipped with a suitable number of trans-modulators converting the digital signals to analog PAL channels. It can be assumed that the solution becomes economically viable for systems with 30 or more outlets.
An economical solution for the distribution of 8 channels from two multiplexes
The components of the set:
- base unit UC-380 R81700 incorporating power supply and broadband RF amplifier with high output level, capable of holding up to 8 individual modules;
- two trans modulators COFDM-PAL RT-316 R81707 (each of them receives one digital multiplex, of which one program can be selected for conversion to analog PAL channel. Other programs from the multiplex can be decoded from the MPEG2 transport stream by "slave" modules DM-316;
- six MPEG2/H.264 TS decoders / DSB modulators DM-316 R817121 for decoding the DVB-T MPEG2 and H.264 signals (TS) and converting them to analog TV channels (PAL)
The base units can be combined for increasing the number of received and distributed programs:
An extended solution enabling distribution of up to 24 programs from tree multiplexes
So, this solution is very flexible. The headed can be easily adapted to the number of available multiplexes and any changes of the transmission parameters (frequencies of the multiplexes, program changes).
Other important feature of this solution is possibility of using modules with CI slots. In the case of introduction of pay DVB-T programs, they may be distributed throughout the premises without the need for additional receivers or cards for any TV (of course the owner of the system should sign the relevant subscription agreement with the content supplier).
The required or recommended systems for residential buildings may depend on the national regulations. In addition to fiber networks, digital terrestrial TV and satellite TV signals can be distributed in many countries through multiswitch systems.
In each case the installer / installation company should obey the local laws.
SMATV systems eliminate individual satellite dishes on facades, balconies or roofs. They improve the looks of the buildings and minimize potential threats to life and health of the residents and other people (taking into consideration strong winds).
Due to a relatively slow development of optical solutions dedicated for the distribution of television signals and high prices of the optical equipment, which do not allow for their widespread use, in many countries multiswitch solutions remain the mainstream of SMATV systems.
For multi-family buildings, DIPOL offers solutions based on Terra equipment. They are used in many countries, among others in UK, Germany, Australia, Poland.
Since 2004, the number of large TERRA multiswitch systems installed in Poland has reached thousands, and they enjoy excellent reputation.
Since 2004, the number of large TERRA multiswitch systems installed in Poland has reached thousands, and they enjoy excellent reputation.
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TERRA SMATV system for 240 outlets placed in a RACK cabinet
The major benefits of TERRA multiswitch systems:
- a complete range of devices allowing for implementation of various projects, for one or two satellite positions, with different topologies (optimal for the building/s) and numbers of outlets;
- scalability - the systems can be used in large single-family houses with ten or so outlets, in apartment buildings with tens or hundreds of outlets, and in multi-dwelling units with up to a thousand of outlets;
- failure-free equipment - professional designs, top-class components, advanced technology, and high quality control standards at the manufacturing and final stage of the production practically eliminate failures in the systems based on multiswitches and other devices from TERRA;
- perfect cooperation with all satellite and terrestrial TV platforms, including DVB-T;
- high technical parameters such as isolation between inputs, isolation between outputs, resistance to interference;
- innovative method of powering system components - a distributed installation wit several hundred outlets can be powered from one 230 VAC power outlet - the devices are powered via signal lines;
- strong technical support for installers coming from DIPOL, as well as provided by SatNet utility developed by TERRA for easy and intuitive designing of even very large SMATV systems.
The SatNet utility for designing TERRA multiswitch systems
SatNet is both simple and powerful design tool suitable for design offices, installation companies, and individual installers. The main features of the software:
- the SMATV projects can accommodate satellite and terrestrial signals,
- includes built-in database of Terra products with their actual parameters;
- has the possibility of defining desired levels of the distributed signals in subscribers' outlets,
- includes the use of cables of different types and classes, also not listed in the database (user-defined),
- automatically adjusts and shows the necessary settings of the active components of the system,
- in a few seconds it shows whether the signals levels in outlets are in conformity with project assumptions and can generate the frequency response for the signals in any point of the system.
SatNet significantly accelerates the designing and implementing of multiswitch systems.
The radial multiswitches provide great opportunities in terms of network scalability. They are ideal for multi-family buildings with multiple floors and staircases. Installation of several hundred outlets may require only one power supply. The main idea of the network is the construction of signal bus which delivers the signals to each subnetwork with MSV multiswitches.
The components of the 5/9-cable systems:
- MSV multiswitches - available for one satellite position and terrestrial TV (used in 5-cable systems) or two satellite positions and terrestrial TV (used in 9-cable systems), with different number of outputs: 4, 8, 12, 16, 24, 32; they can be powered remotely (via H lines) or locally (from a power supply located in the same installation box),
- launch and line amplifiers - used in situations where the signal is to be distributed in large buildings and/or to a large number of outlets; launch amplifiers can also supply power (via H lines) to multiswitches and other system components,
- splitters and taps - divide the network into subnetworks serving smaller groups of subscribers,
Modernizing an existing multiswitch system or building a new one, the installer should put special emphasis on the proper selection of coaxial cables.
The most important parameters:
The most important parameters:
- attenuation (multiswitch systems distribute signals in very wide frequency band: 47-2400 MHz); cheap cables are not suitable for these systems due to high attenuation, especially when the distances between the LNB and receivers are long;
- screening efficiency - cheap cables have poor shielding which causes crosstalk between adjacent cables in the harness (arranged of 5 or 9 cables), decreasing C/N ratios.
The topology of multiswitch systems in buildings with multiple floors and staircases depends on the number and layout of the outlets (two main solutions).
- The first solution is dedicated for buildings with relatively small number of outlets in each staircase, not beyond the capacity of a single multiswitch (up to 32). It is possible to implement it in the case of a larger number outlets, however it would require to use additional coaxial cables in shafts.
The cable bus, composed of 5 (for one satellite position) or 9 (for two satellite positions) Triset E1015-113 cables, goes from the roof to the basement / garage / underground car park, and then (at the basement/underground level) to next staircases with taps providing signals for the multiswitches with the required number of outputs.
/Legend: terrestrial TV antenna, satellite antenna, tap, multiswitch, outlet/
Wiring diagram of a system with one quatro LNB in building with maximum 32 outlets in one staircase
Wiring diagram of a system with one quatro LNB in building with maximum 32 outlets in one staircase
/Legend: terrestrial TV antenna, satellite antenna, tap, multiswitch, outlet/
Wiring diagram of a system with two quatro LNBs in building with maximum 32 outlets in one staircase
Wiring diagram of a system with two quatro LNBs in building with maximum 32 outlets in one staircase
- The second solution is recommended for buildings with very large number of outlets, particularly for high apartment buildings and other buildings where the number of outlets on each floor is relatively large (e.g. ten or more).
The cable bus is also run from the roof to the basement / garage / underground car park, and then through all the staicases at the basement/underground level. In each staircase there is main tap at the lowest level, and the bus going up in the shaft to the highest floor, divided by another tap on each floor into a subnetwork. This way, the number of outlets on every floor and in the whole building is virtually unlimited.
/Legend: terrestrial TV antenna, satellite antenna, tap, multiswitch, outlet/
Wiring diagram of a system with one quatro LNB in building with more than 32 outlets in one staircase
Wiring diagram of a system with one quatro LNB in building with more than 32 outlets in one staircase
/Legend: terrestrial TV antenna, satellite antenna, tap, multiswitch, outlet/
Wiring diagram of a system with two quatro LNBs in building with more than 32 outlets in one staircase
Wiring diagram of a system with two quatro LNBs in building with more than 32 outlets in one staircase
