THE choice of multi-channel television viewing in Ireland ranges from deflector, MMDS, cable and satellite systems. The technology, reception, costs and number of channels available vary greatly depending on which system the viewer favours.
In terms of technology, each system is distinguished by the waves it deploys to convey TV signals. These are differentiated by their frequency. Deflectors use ultra-high frequency waves (UHF), supposed to be the reserve of domestic TV channels. Cable uses a higher frequency known as very high frequency (VHF) waves. In the case of MMDS, waves are of a much higher frequency again, and satellite systems fall into a similar higher frequency band.
Deflectors: Most people in rural Ireland with multi-channel TV get their signal from one of the estimated 100 illegal deflector systems in the State. It is simple technology using UHF waves, which are supposed to be restricted for use by national stations such as RTE and TnaG.
A typical system would work with aerials on high ground picking up a weak signal from BBC1, BBC2, UTV and Channel 4 transmitted in Northern Ireland.
When that is picked up by a "quad" or four aerials, it is converted to another frequency. It is then amplified and transmitted. Houses with ordinary HF aerials which receive RTE - pick up the signal by having their aerial pointed in the right direction.
The service is often free. It is usually provided by community groups. No royalties are paid but households may be charged between £25 and £40 a year to cover maintenance and equipment.
Some 150,000 households concentrated in 12 counties avail of deflectors.
Typically, a system consists of the aerials, a small building for equipment, access to an ESB supply and sometimes a back-up generator. The signal can be sent from one system to another, so that when the signal from a deflector is getting weak, 20 to 30 miles from the transmitter, another system can pick it up and send it out again.
Service issues: Quality of signal can fluctuate. Households often have periods when the signal is down.
MMDS: where deflectors are cheap, the provision of microwave multipoint distribution system is expensive to install and operate. A signal retransmission station" costs about £500 000 The technology involved is more complex. MMDS use wave signals which have a much higher wave frequency (2.5 Gigahertz).
Transmission began in 1991 after companies were offered franchises for specific areas. They were directed to higher wave band because the UHF band was considered crowded. There are 30 MMDS transmitters on high ground around the State. Signals are beamed direct to customers or to subsidiary transmitters, known as beambenders, to cover blind spots.
MMDS signals are encoded and unscrambled by subscribers who have a special unit attached to their television. Typical costs are £90 to £120 for a connection and £135 rental a year for a basic package of eight channels. Some 95,000 homes avail of MMDS.
Service issues: MMDS subscribers are restricted to about 12 channels although franchise holders are anxious to be allowed carry more. Subscribers cannot video a programme if it is other than what they are watching. Difficulties can arise in bringing the signal to some areas, while there have been allegations that MMDS transmission poses health risks.
Cable television: these services are concentrated in urban areas and involve the use of a cable connecting into a subscriber's house along which the TV signal is conveyed - hence the term piped television.
It uses a large aerial to receive high-frequency signals from a satellite or conveyed in microwave form. They are then sent to a processing centre to change them to a lower frequency before being transmitted through a VHF network to households. A total of 415,000 subscribers have cable. They pay about £100 a year rental and a connection fee of up to £250.
Service issues: Cable is the single most successful form of multi-channel transmission but the number of channels available depends on the grade of connection to households. Some have been upgraded to allow extra channels to be added to a basic 14 to 16 channels.
Satellite television: This involves the use of a satellite dish on a building. On purchase of a card, it allows up to 99 channels to be beamed into a home. A dish and receiver costs about £200 and up to £100 to install. Sky Television said last year 70,000 people in Ireland were availing of its satellite packages. The current estimate is 80,000.
Service issues: Dishes are not allowed on some buildings Subscribers are responsible for costs of repairing or maintaining dishes. While some systems have a restricted number of channels, a dish goes to the other extreme. Viewers are spoiled for choice and many channels may be surplus.
