High Definition TV
What is High Definition TV or HDTV?
High definition television is a new technology that enhances the picture quality on a television set. Currently, the picture on our screen is represented by a number of small dots called pixels. These pixels are arranged into lines and the current PAL (UK) standard is to have televisions that display 625 lines of pixels. Under the new HD technology, resolutions are increased to typically 720 or 1080 lines.
To broadcast just one HSTV channel using the current analogue TV system would use all the available bandwidth, meaning that all the other channerls would have to be switched off to make room for it.
At the moment, it is impossible to send HDTV signals using terrestrial transmission. Until all the analogue signals are switched off and UK television becomes completely digital in 2012, HDTV broadcasts will only be available on satellite and cable television.
Why do we need HDTV?
On smaller TV screens the current standard is adequate. But with today's trend towards larger screens - the average size of a tv screen is now 38"' compared with 24" ten years ago, more definition is require to get a top quality picture, with razor sharp images. The picture is also broadcast in 16:9 widescreen format comparable to that in a cinema.
Sound too is enhanced - HDTV incorporates Dolby Digital 5.1 channel surround sound.
What do I need to become HD ready?
You will need:
Will an HDTV still play the none HD format?
Yes, all HDTV's will be compatible with both the HDTV and none HDTV signals.
How do I know if a television I am about to buy is HD ready?
It should have a "HD Ready" sticker attached. In addition, it must have HD connectivity. which means it must have connectors on the back which can receive the HD signal - usually labelled HDMI (see adjacent picture). A DVI connector is also HD but less popular in the UK - a cable is available to plug DVI outputs into HDMI inputs and vice versa.
HD ready TVs will not only display the current 625-line broadcasts, but they can also display the 1080-line programmes of the future. It is likely that 625-line broadcasts will continue alongside 1080 lin HD for a few years to allow people to change their television. Eventually, the 625-line system will be switched off.
Televisions that support a resolution of 1920x1080 will be able to display true High Definition pictures. Some televisions that are HD Ready support lower definitions than this so you need to check the supported resolution of the TV that you are about to buy.
When will TV programmes be transmitted in the HDTV format?
The BBC plan to transmit all programmes in the HDTV format by 2010, and are transmitting a few programmes in this format now. Sky Television are currently transmitting HD premium channels including Sky Sports HD, Sky Movies HD, Sky One HD, Artsworld HD, National Geographic HD, Discovery HD, Sky Box Office HD and BBC HD.
Should I buy a HD ready television now?
If you are going to replace your television anyway, I would say yes, you may aswell buy one that is HD ready. However, if you are perfectly happy with your current set that is not that old, I would stick with it. New technology always comes down in price - in fact, the price of an LCD television dropped by about 45% last year, so it might be worth holding back a while. Also, if you have a small room that cannot accommodate a larger television, you may not notice that much of a difference with this new technology.