SignalNET - telecommunications and RF distribution systems in multi-dwelling units

The latest regulations in Poland concerning signal distribution systems in multi-dwelling units and public buildings specify more precisely requirements for cabling systems being deployed in new buildings. The purpose of the requirements is to unify the provision of services for every user by allowing access to broadband Internet, terrestrial and satellite television, telephony etc. - not restricted to one operator or technology.

Similar requirements are or will be compulsory in many countries, so that the investors must take them into consideration. Even if such regulations have not been passed yet, the fulfillment of the recommendations will make the buildings more attractive for the customers/residents.

FTTH (Fiber-To-The-Home) technology greatly improves the quality of broadband services, in particular allows the users faster data transmission rates, especially important for streaming HD video; the medium is also much safer for the users' equipment - no surge voltages.

The optimal solution is to combine both installations into one multiswitch system that, using one coaxial cable, provides all the signals to each apartment. Thanks to this solution, the residents are not forced to pay for services of cable TV operator - they can receive free DVB-T broadcasts, FTA and pay TV satellite channels.
A very important fact is that residents of buildings without multiswitch systems had to mount their own satellite dishes (in Poland about 50% TV viewers have been using satellite receivers) on balconies and facades of buildings, which spoiled the overall aesthetics of the buildings. People having apartments only on north and west sides of the buildings were deprived of access to satellite signals from Polish operators. Multiswitch systems eliminate such problems.

Codes	Names	Declaration PL	Declaration EN
R70858, R70862, R70866, R70874, R70882	Multiswitches of MV-9XXL series
R70901, R70911	Amplifiers of SA-91L series
R70524, R70525, R70526	Taps of SD-9XX series
R70526, R70529	Splitters of SD-9XX series
R48602, R48606	Signal protectors

 

For applications in multi-dwelling units, DIPOL recommends renowned TERRA multiswitch solutions. They are widely used in Great Britain, Germany, Australia, Poland. There are thousands of implementations worldwide, with many, many thousands of satisfied users.

Multiswitches are the flagship products of TERRA company. Due to excellent scalability, they can be used both for implementations of small and very large systems, up to 2,000 outlets. Systems with hundreds of outlets can be powered from only one AC power outlet. The concept of the large systems is based on signal bus and division into subnetworks with MV-9XXL multiswitches.

Active of terrestrial TV path. Possibility to adjust the gain of the terrestrial TV path and the SAT path for two satellite positions (separately for each of the 8 pairs of IF polarization-band signals).

Below the technical data for MV-908L R70858, MV-912L R70862 and MV-916L R70866 multiswitches is presented.

TERRA's MV series of multiswitches models offered include also: MV-924L R70874 and MV-932L R70882

The use of amplifiers SA-91L/91DL allows you to build extensive multiswitch systems with up to several hundred outlets. Signal level control with switches ensures stability of parameters over time. The die-cast housing provides high screening efficiency preventing the penetration of interfering signals inside the device.

Taps are used in multiswitch systems, to separate signals from the multiswitch bus (2x4 SAT +1 TV cable) for the multiswitch subnetwork. The molded housing provides excellent screening over the entire range of transmitted frequencies.

Splitters are used in multiswitch systems, to split the signal from the multiswitch bus. The bus with the signal from two Quatro LNBs consists of eight cables. In addition, the splitter divides, also the terrestrial TV signal. The molded housing provides excellent screening over the entire range of transmitted frequencies.

Regulation of the Ministry of the Interior and Administration of November 6, 2012 specifies the following requirements against surges in telecom systems of residential buildings:

Signal surge protection box R48606 has been designed for comprehensive protection of SMATV systems based on multiswitches. The device protects the system against voltage surges induced in signal lines by lightning strokes.

The box has been equipped with 12 Signal TV-Sat surge protectors R48602 that can protect:

Regulation of the Ministry of the Interior and Administration of November 6, 2012 specifies the following requirements for coaxial cables in telecommunications systems of residential buildings:

One of the coaxial cables brought to the telecom subscriber box can be used for the provision of services by cable TV operators. Due to the fact that cable networks also use coaxial cables for the transmission of Internet services using the band of the so-called return channel (frequencies of 5...65 MHz), we recommend the use of cables with increased screening efficiency in the return channel band, such as Triset-PROFI E1010 (screening in the bands 30-1000MHz >110dB - class A++).

These parameters are met by single-mode G.652.D fibers. Of course, they are also fulfilled by the G.657.A1/A2 fibers with reduced minimum bending radius.

The requirements are met by the cables below:

The main criterion in selecting fiber optic cabling for a building system is the topology of the system on which the network will be built. There are two dominant trends - systems based on the so-called. easy access cable and star systems, in which the L7102 2-fiber flat cable, ideal for FTTH technology, is most often used. The choice of the type of topology is usually determined by the number of apartments in each block and on each floor.

The basic criterion for the selection of a distribution frame/box is the way mounting, on a wall or inside a rack cabinet. Of course, the enclosure must have suitable capacity depending on the number of terminated fibers and other network components. For use in apartment buildings, the most popular models of distribution frames/boxes can accommodate from 12 to 72 fibers.

All distribution frames/boxes should be equipped with SC/APC adapters for connecting pigtails. A good practice is to use the same type of fibers throughout the whole network.

When the designer plans services provided via xPON technology, the distribution frames should have place for optical splitters. Optical splitters, similarly to RF splitters, divide the transmission paths to several sub-paths. Commercially available splitters enable the division into up to 32 branches.

Other Ultimode splitters:

• ULTIMODE SO-8-7A 1x8 L36081
• ULTIMODE SO-16-7A 1x16 L3616
• ULTIMODE SO-32-7A 1x32 L36321

In the case of termination/subscriber boxes, the very important issue is the security of the installers and users - the connectors have to be covered or directed downward.

In the example, the building has 5 floors with 3 apartments on each floor. According to the requirements specified above, the installation contains 30 fibers, with two terminations in each apartment.

The technical room houses RACK cabinet R912012 with two fiber optic boxes ULTIMODE MT-524 L5124 with front panels L5541. The boxes can accommodate up to 48 SC/APC adapters L4222. The optical cables to the subscribers are distributed from the rear of the cabinet - they are welded with SC/APC L3552 pigtails placed inside the boxes.

The apartments are connected with the technical room via fibers of ULTIMODE BS easy access cables. The apartments on the first (ground) floor are connected by the fibers of the BS-12SM L7812 cable composed of 12 fibers, on the higher floors - of the BS-24SM L7824 cable composed of 24 fibers. On each floor, 6 fibers are extracted from the cable after cutting suitable window with special stripping tool L5911. The windows are protected by breakout units VC-CPC L5350, specially designed for easy access cables. Each pair of the fibers going to an apartment is protected by drop/distribution tube VC-TUB L7211.

In each apartment the fibers can be terminated in several ways, either in the case of using termination box or outlet. The best solution seems to be a small termination box housing the fibers terminated in a way that will not require the user to engage a professional service to splice them for the future use. It may be termination box ULTIMODE TB-02H L5302 containing spare lengths of the fibers, spliced with SC/APC L3552 pigtails terminated with L4222 adapters.

Considering the number of outlets and their layout in a building, we can distinguish two main cases. In the case where the total number of outlets within a single subnet (usually encompassing apartments in one staircase) is relatively large (above 32), a good solution is to install multiswitches in boxes on each floor to provide the signals to the apartments on the floor.

The main advantages of this solution are limited number of the cables in shafts and division of the distributing network into small, independent subnetworks. This segmentation allows for virtually complete elimination of a massive breakdown of the system.

The solution presented in the figure above, based on Terra MSV multiswitches and tap-off line concept (cable bus) is the most optimal one in terms of the number of components. Due to a small size of the subnetwork in the example (encompassing 15 apartments located in a single staircase of a 5-story building), all the apartments can be served by one multiswitch. The SMATV system distributes signals from two satellites (e.g. Hotbird and Astra) received by two dishes equipped with QUATRO Inverto Black Ultra A98266 LNBs, and a range of terrestrial signals, received by DVB-T antenna Dipol Tri-Digit A2670, VHF antenna Dipol-4/DAB A0140, and FM antenna Dipol 1RUZ PMB A0221.

The cabling consists of 11 coaxial cables Triset-113 E1015 going from the roof to the technical room containing all active devices. In the case of a higher building or when the distance from the antenna set to the technical room is longer than 25-30 meters, it is recommended to install additional installation box with amplifiers, located close to the antennas (in the attic or on the highest floor). In the presented solution, all the cables to the subscribers run from the room. Because of large number of cables going in parallel, they should have very good screening efficiency, like TRISET-113 E1015.

More on topologies and solutions of multiswitch systems can be found in the excerpt of another article, Example diagrams of multiswitch systems

The technical room contains:

Selecting the equipment for a multiswitch system, the designer has to take into account the attenuation in all paths, to ensure proper signal levels in every subscriber outlet. The figure below shows a part of the project of the previously introduced system, made ​​with the use of free Terra SatNet utility.

Key features of Terra SatNet utility:

The diagrams that we have prepared with SatNet software (.dwg files), everyone can use for practical implementations of systems based on Terra devices. The .dwg files can be found in the catalog pages of the devices (Available downloads), e.g.

Telecommunications box in each apartment is connected via two UTP cables NETSET E1408 with the technical room that is the connection point with telecommunications networks. One of the cables can be used, for example, by door entry system. The cables in the apartment boxes can be terminated e.g. with two-port patch panels, for easy connection with the cabling installed inside the apartments.

The cables from the apartments go down through the shaft and enter the technical room with 24-port (CAT5 RJ45) patch panels R9120316. This way the service providers can easily connect their switches installed in the room to the building network.