Digital TV Types

Digital Television in the UK is transmitted using three media. Each has its own operator, which means to say that each company controls what is transmitted on its own network. These companies (with a couple of exceptions) do not produce their own programmes, but buy in programmes from independent makers such as the BBC or Carlton. These programmes arrive in digital format from the original sources and are multiplexed together on the distributor's network by the network operator.

Terrestrial

As from October 30th 2002, Terrestrial Digital TV broadcasts are controlled by a consortium called 'Freeview'. Signals are detected by a normal rooftop antenna (in most cases the same one that received the old analogue TV) but are decoded by a special box before being passed on to the family TV. Some new Digital TVs have the ability to decode these signals directly.

DigiTV is designed to decode Terrestrial Digital broadcasts. The majority of Terrestrial Digital broadcasts are free-to-view in the UK. In the middle of 2004 a company called TopUp TV started to broadcast several encrypted channels in the UK which could only be received by a handful of set top boxes which contained the appropriate decryption hardware.

Now, with the appropriate additional hardware and a valid subscription card, you can view these new channels with DigiTV. For more information about this please click here.

Satellite

There are a considerable number of communication satellites in geostationary orbit currently servicing the UK and Europe; including Astra, EutelSat and Hotbird. Each relay a variety of Analogue and Digital transmissions from the originating stations on Earth back to overlapping footprints across Europe.

The programmes are received with a parabolic antenna/LNB combination pointed in the direction of the satellite's position in space. Most modern antennas are small, unobtrusive offset-focus types made of wire mesh to further diminish their conspicuousness, although they can still be seen adorning the south-facing walls of many houses in the UK.

As with terrestrial broadcasts, a special decoder box is needed to interpret the digital signals before they can be viewed on a conventional TV. Many channels are subscription only (for example the movie channels) and so are encrypted at source using the VideoCrypt system. The decoder boxes have a port that accepts a smart-card so that these channels can be decoded by those wishing to subscribe.

Cable

Cable operators such as NTL and Telewest prefer to transmit their programming over optical-fibre/coaxial cable. The link starts at the network operator, then progresses via repeaters underground until it arrives at the subscribers' houses.

The cable companies take additional advantage of their network by offering other services that make use of spare bandwidth: video-on-demand, broadband internet connections and telephone facilities.

Again, a special decoder box is needed to interpret the digital signals before they can be viewed on a conventional TV. The cable decoder boxes also have a port that accepts a smart-card so that empowered viewers can watch encrypted channels.