What is TV Signal Distribution?
Traditional TV signal distribution is how TV & Satellite RF (Radio Frequency) signals – which carry the TV and Radio channels – can be distributed around a building or complex to serve multiple points or users.
In a standard house, the distribution system might simply be a coax cable connecting the TV aerial or Satellite dish on the roof to the TV or Satellite outlet behind the TV set.
However, in a block or flats or large office, the distribution system will be a complex network of cables and RF amplifiers, splitters, switches and other specialist equipment.
Other methods for distributing TV are IP (stream TV signals over a LAN network – typically used in offices) or HDMI (used within the home to distribute TV signals between equipment and sometimes between rooms).
What is an IRS?
IRS stands for ‘Integrated Reception System’.
An IRS collects RF signals (carrying TV, Satellite and Radio) from one or a small number of aerials and satellite dishes and distributes those signals a number of locations, such as different apartments or offices.
Most IRS systems will provide at least signals for Terrestrial TV (Freeview), DABs/VHF Radio and Astra Satellite (Sky and freeSat). Some will also provide signals for other satellite services such as HotBird or Arabsat.
An IRS can cover anything from a few flats to an entire village or office block. Most new housing blocks will have an IRS.
The big advantage, over each subscriber having their own TV aerials and dishes, is that it looks tidy, with no unsightly proliferation of TV aerials and satellite dishes on the side of the building.
MATV stands for Master Antenna TV.
MATV is the same as IRS except that it only distributes TV and Radio signals – not satellite.
For technical reasons, it is easier to build a MATV system than an IRS and if satellite isn’t required a MATV system may be attractive.
What is SMATV?
SMATV stands for Satellite Master Antenna TV.
SMATV is the same as MATV in that it only distributes TV (UHF) and Radio signals.
The difference is that it will also include facilities at the head of the system to decode certain satellite channels which it will distribute as additional TV channels.
New SMATV systems are typically only used in Hotels or Gyms.
What is the difference between SMATV and IRS?
Both SMATV and IRS systems will distribute off air TV and Radio channels to multiple subscribers.
However, whereas a SMATV system will only distribute selected satellite channels at UHF frequency, an IRS will distribute the raw satellite frequency signals so every subscriber who can then connect their own satellite receiver equipment (such as a Sky box or freesat receiver).
So, an IRS is general purpose reception system which presents signals to each subscriber as if they have their own TV and Radio aerials and satellite dish(es), whereas a SMATV restricts the satellite reception to a number channels which are distributed as additional UHF TV channels.
A SMATV system is only applicable for specialist areas such as Hotels and Sports Centres, where the TV receiving equipment is centrally managed. Even in these areas, the emergence of digital TV and IPTV means that SMATV is being superseded by newer technologies.
What is FIRS?
A FIRS provides the same functionality as an IRS, except that the underlying technology uses fibre cable rather than copper coax cable.
The traditional IRS uses electronic equipment such as amplifiers and multi-switches to distribute the TV and Satellite signals over coaxial copper cabling. A FIRS uses completely different technology to distribute the TV and Satellite signals over optical fibre.
The advantage of FIRS is that it can operate over much longer distances and because of the higher bandwidth of fibre, can ultimately provide more satellite services over a smaller cable.
More commonly, many new IRS’s are being designed as hybrid systems, utilising fibre for the backbone routes (taking advantage of the higher bandwidth and distance capability of fibre) but still using coax copper to the home.
Why use fibre for TV distribution?
There are a number of possible advantages to using fibre over copper cable:
- Longer distances. Fibre allows RF signals to be transmitted over much longer distances. Using a traditional copper coax cable, due to signals losses through the cable, satellite signals need to be re-amplified every 100 – 200 metres (depending on the thickness of cable). However signals may be run over several km of fibre before re-amplification is required.
- Fewer cables. For backbone links, fewer cables will typically be used with fibre. For example, using the Global Invacom fibre technology, to implement a four satellite service backbone would require one 4-core Single mode fibre cable compared with sixteen Coax cables.
- Convergence with fibre to the home. Driven by the demand for high speed internet in the home, there will be an increasing focus on connect fibre directly into homes over the next decade. Cores in the same fibre may be used for feeding TV signals.
How can I add international satellite services to an IRS?
However, it is a common requirement to receive signals from other satellites. Popular international satellites in the UK include Hotbird, Arabsat and Nilesat.
Satellite services can be added to an IRS by adding more satellites dishes at the head end and more backbone cabling and equipment to cater for the extra signals.
However, although it is possible to add satellites to an existing IRS, overall it is much more cost-effective if the IRS has been designed and built for this purpose in the first place.
A popular initial configuration is to offer Hotbird as well as Astra – Hotbird carries a broad section of European and Arabic channels.
What TV sockets are required in a home connected to an IRS?
It was once the case that only one TV outlet was normally required in a home, in the lounge.
With the proliferation of low cost TV’s, it now popular to require at least one TV outlet in every main room or bedroom.
However, there are a number of different ways of organising the TV sockets, with differing levels of functionality, flexibility and build cost:
- The minimum arrangement is for a TV/Satellite socket in the lounge (normally two separate feeds to provide for Sky+) and a single slave TV socket in the master bedroom. If the IRS caters for additional satellite services, these can be added to either or both the signals to the lounge.
- If TV sockets are required in all bedrooms, then each can have its own slave TV feed. However, if the number of bedrooms is more than two, this will require a small TV amplifier to boost the signals.
- It is increasingly popular to want satellite signals in more than just the lounge. For example, it would not be uncommon to install a separate SkyHD box in a bedroom. This can be achieved by bringing several feeds from the IRS to a service cupboard and star wiring from here to various TV/Sat outlets in the dwelling. By adding a patching facility, the tenant is the able to route the satellite signals to wherever they are required.
- At the next level of sophistication, all outlets can have their own dedicated feeds from the IRS. These can be fed either directly from the building IRS or from a multiswitch fitted within the dwelling’s service cupboard.
What is IPTV?
IPTV means distributing TV over an IP data network (or LAN). It is applicable where there is already an installed building-wide structured cabling system and network, hence saving the requirement for additional coax cabling.
An IPTV system will consist of a IPTV headend, which will take terrestrial TV and selected satellite channels (very like SMATV) and makes them available on the LAN.
Users, can then view these channels at any point on the LAN, either from a LAN connected PC or from a standard TV connected to the LAN through an IPTV decoder.
When is IPTV applicable?
IPTV is most suitable for organisations where there is already a network and several TV’s will be required.
Typical users are offices, hotels and entertainment complexes.