HDTV stands for High Definition Television, and if you live in the USA, Australia, or
Japan you may already have experienced it. There are three key differences between
HDTV and what's become known as standard definition TV ie regular NTSC, PAL or
SECAM. The three differences are; an increase in picture resolution, 16:9 widescreen
as standard, and the ability to support multi-channel audio such as Dolby Digital.
The most important aspect of HDTV, and the one which gives it its name is the
increased resolution. Standard definition NTSC broadcasts have 525 horizontal
lines, and PAL broadcasts are slightly better at 625 lines. In both these systems
however, the actual number of lines used to display the picture, known as the active
lines, is fewer than that. In addition, both PAL and NTSC systems are interlaced, that
is, each frame is spit into two fields, one field is the odd-numbered lines and the
other is the even lines. Each frame is displayed alternately and our brain puts them
together to create a complete image of each frame. This has an adverse affect on
HDTV is broadcast in one of two formats; 720p and 1080i. The numbers refer to the
number of lines of vertical resolution and the letters refer to whether the signal is
progressive scan, 'p', or interlaced, 'i'. Progressive scan means that each frame is
shown in its entirety, rather than being split into fields. Both systems are
significantly better quality than either PAL or NTSC broadcasts.
HDTV uses 16:9 widescreen as is its aspect ratio so widescreen pictures are
transmitted properly and not letterboxed or panned and scanned. Dolby Digital
multichannel sound can be broadcast as part of an HDTV signal, so if you have a
surround sound speaker set-up you can use it to listen to TV rather than just DVDs.
To receive an HDTV broadcast you need either a TV with a built-in HDTV tuner or a
which can pick-up off the air HDTV channels, or cable or satellite HDTV like. You
also need to live in are where HDTV channels are broadcast or distributed by cable
Currently HDTV is widespread in Japan and is becoming commonplace in the US,
with most major networks distributing HDTV versions of their popular content. The
2005 Superbowl led to a large increase in the demand for Fox Sports HDTV and
cable companies scrambled to add it to their offering in the run up to the game. In
Autralia, HDTV uptake was sluggish initially but has increased significantly since
The situation in Europe is not so bright. There is only one company broadcasting
HDTV in the whole of Europe, Euro1080, and it has only two HDTV channels, both in
the 1080i format. Euro1080HDe shows major cultural and sporting events to
cinemas and clubs around Europe, while HD1 broadcasts sports, opera, rock music,
and lifestyle programs via satellite to homes in Europe. UK satellite broadcaster, Sky,
which is owned by Fox proprieter Rupert Murdoch, has announced plans to
broadcast some HDTV content in 2006. The BBC has also made noises about
broadcasting HDTV programs (it already films some programs in HD format).
However, it will be a while before HDTV in Europe catches up with the rest of the
world. The controversy created by the confirmation of plans by the UK government
to start switching off analogue transmitters in 2008 showed how many people have
yet to make the switch to DVB-T. That will be used as an argument to show that
there is no appetite in the UK for another major change in TV broadcasting -
particularly as most people think they already have 'digital TV' in the form of DVB-T.
Given that television was invented by a Briton, and Europe led the way with PAL for
so long, this is a rather sorry state of affairs.
Kenny Hemphill is the editor and publisher of The HDTV Tuner - a guide to the kit, the technology and the
programming on HDTV.