HDTV buyers' guide

By Richard Taylor Editor, BBC Click

The bottom line is pretty simple. You will need a suitable display device; the bigger it is the more noticeable the difference between standard definition and high-definition.

Q&A: High-definition TV

Bear in mind it does not have to be a TV. High definition projectors are no longer that pricey, and they really do give you that fully immersive experience.

You will also need some way of getting content into that set, usually in the form of a separate tuner to receive the HD signal.

In Europe there is a standard called "HD Ready" so look out for a logo which guarantees your display is up to the job of producing HD images.

It is a good starting point to look at some of the key features of HDTV.

First off, to show off all that extra detail HD Ready hardware guarantees that the screen can deal with the high-definition broadcasts.

HDTV IN EUROPE Commercial HDTV services began with Belgian channel Euro180 in 2004 Telewest launched the UK's first HDTV service in March 2006. BBC and Sky began HDTV transmissions in May 2006 BBC to have 100% HD programmes by 2010

Depending on the broadcaster they are either 1280 pixels across by 720 lines, or 1920 pixels by 1080 lines.

Your set will need at least 720 vertical lines in a widescreen format - the HD standard.

Of course the set has to have some way of getting the HD signal in the first place.

The ideal way to get your sound and pictures delivered is through the digital High-Definition Multimedia Interface (HDMI) port.

To be HD Ready that digital HDMI slot must support the HD content protocol or HDCP. This is basically a copy-protection measure to stop us digitally recording and redistributing HD content at our leisure.

HD Ready is not the be-all and end-all. If you have a good quality high resolution display but it does not have the digital HDMI input, it could probably still receive HD images if it has a high-quality analogue component input, you just need to ensure your set-top box can send it an analogue signal.

On the other hand, some displays are billed as "HD-Compatible", but here you have got to be careful.

They might have the right digital inputs but they do not have a high enough resolution to support the full HD signal.

For instance, say your display has only 540 vertical lines. But as HD is broadcast in at least 720 lines, it means that the TV has to squeeze and downgrade the signal to display it. It is not ideal.

Tuners

The tuner or set-top box is the unit which receives and decodes the HD signal before pumping it out to your TV.

If you look round the back of a first-generation box from Sky you will see it has all the usual stuff you would expect, including a HDMI output.

The World Cup is being pushed as a major reason to upgrade to HD

But it also has the analogue component out, which you will remember means you can send your HD image to analogue input on your TV.

Note also the optical audio output which means if you have a surround sound amplifier you can enjoy the Dolby digital sound promised by HD broadcasts.

The interface is pretty similar to existing Sky boxes - with the red button reserved for your HD channels.

The box also sports an expanded 160GB hard drive to store around 40 hours of HD programming, which partly explains its £300 price tag.

With Sky, or indeed cable provider Telewest, you will also have to pay a supplement on top of your existing subscriptions.

One important tip: when you are choosing your HDTV and set-top box try to make sure you can see them working together before you buy.

Teething problems

HDTV is still a very new technology and I have come across a few sync problems where the image runs slightly behind the sound, and it is really quite annoying if the two do not match.

Even though most of the time you have to pay for HD content that is not always the case, and you could plump for a tuner.

These boxes do not even have a slot for a subscription card - but they will give you free-to-air HD channels like the BBC's.

If you are desperate to watch the BBC's HD coverage of the World Cup or Wimbledon, and can not get hold of a cable or Sky box or do not want to pay for a subscription, these should see you right and they are quite cheap too.

However, this is just in its trial stages and you will not be able to pick up any premium content.

One final thought, most of you can probably already experience HD without opening your wallet at all or hooking up any new kit. How? Easy.

Most modern PCs can process HD images, and your display will too, as long as its resolution is 1280 by 720 or higher resolution.

And online, courtesy of Apple, Microsoft and others, you can download plenty of free content - albeit mainly showcase stuff and movie trailers.

But, of course, the bigger the display the more noticeable the difference between standard definition and HD.