What is digital TV?
For a start, it's a better way of sending sound and pictures to TV sets. Previously, because they were analogue - transmitted in a wave of varying values - they were liable to become distorted or weakened during transfer. But digital signals are a much "cleaner" stream of ones and zeroes or "ons" and "offs" - so it's much easier to read this stream of digital bits, even a very faint signal - and convert it back into a picture or whatever. Hence the quality of digital TV is far superior to the old analogue system.
But doesn't it mean more channels too?
It basically compresses broadcasting signals, so they take up less space on the airwaves. This frees up frequencies for hundreds of new channels.
As simple as that?
No - digital TV comes in three forms. Digital terrestrial television is received via standard TV aerials. This is the form involved in last June's announcement in Britain, when a consortium won the licences to operate. Then there are digital satellite TV and digital cable TV, each offering some advantages and disadvantages.
Who will be doing it?
Existing terrestrial broadcasters have been allocated blocks of digital channels, and in Britain's case three more blocks of channels put up to auction, and British Digital Broadcasting won. Its backers are Granada and Carlton.
But how many channels will there be?
If all the multiplexes, or bundles of channels, are added up and compressed as much as possible, perhaps 50 new channels or more in some parts of Britain and Ireland. In fact there will be so many channels that people are even talking about being able to decide which camera angle you want to watch - or which combination of camera angles to have on your screen at the same time.
For example, while following the Grand Prix you could decide to watch what is happening to Jacques Villeneuve in the pits, even though the "main" channel is focusing on Michael Schumacher on the track. You simply flick to another channel where the pit-stop is shown, or combine both channels on the same screen.
It all sounds like TVs are be- coming a bit like computers. Well, there has been much debate in the industry about how much TVs will become PCs, or PCs will become TVs. Either way, televisions and personal computers are converging
rapidly, bringing us closer to a time when a single large screen on the wall could act as cinema screen, computer monitor, telephone and TV. Digital TV offers the possibility of other, two-way signals between the TV broadcaster and the end user - "interactive TV", Internet-type services, home banking by these channels, and so on.
What will you need to receive digital TV?
A set-top box for a start. This turns digital transmissions into pictures on a standard TV.
What will it all cost?
The set-top boxes will probably retail for about £200 in Britain and (as usual) slightly more here. Many of the new channels are also likely to be offered on a pay-per-view or subscription basis. With so many channels, digital TV could also mean a lot more narrow-casting
- increasingly specialised channels, often as pay-per-view. For example, there has been talk of the English Premier League's major clubs and even the GAA having their own pay-per-view digital channels (the "Man United Channel", "TV GAA GAA" and so on), cutting out the middleman as it were.
With all these channels, how will you be able to find what you want to watch?
The information about the programmes will also become increasingly digital. Electronic programme guides (or EPGs) will be like a sort of electronic RTE Guide, available through a sort of zapper and the set-top box. You pre-select types of programmes you want - e.g. cookery, soccer and the news - and the EPG picks out the times of those programmes on all the hundreds of channels and schedules them for you.
What else?
Digital TV allows for backchannels.
These aren't broadcasting channels as such, but phone lines (or Internet connections) operated by a telecom company. But they will be available through your EPG on the same TV set - thanks to all information being coded in the same digital "on-off" language.
These back-channels will enable viewers to download information about a specifically chosen topic, similar to tuning into a teletext page. For example, before watching a horse race (yes, the examples almost always seem to be of sports) you could select information about the different horses - and maybe even video clips of their previous races.
And when will all this happen?
DTT could appear on some channels by the end of next year. Some cable and satellite services might even be up and running before then, offering hundreds of channels.