What exactly is HDTV?
Normal TV sets work in an analogue fashion with a 6 MHz signal being broadcast from television transmitters around the country. This signal carries all the important information such as the picture and sound through the air waves. Analogue TV’s pictures are refreshed every 30th of a second in which half of the lines are refreshed every 16th of a second. This kind of display is known as an interlaced display.
Because of the recent advances in technology such as the introduction of TFT’s and LCD displays the average home user is now used to much better clarity and detail of picture that these products provide due to the resolution they work at.
Some of the new technologies such as DVD’s use digital encoding to allow them to provide superior picture and sound quality. Because most TV’s still work in an analogue mode, a conversion must be done to the incoming signal from the specific device. This allows the picture to be displayed in a better quality than normal VHS tapes. Just imagine how good the picture and sound quality would be if this conversion did not have to happen and the signal went from a digital to digital device without any interference.
To get pure digital TV, the actual transmission signals must be broadcast over the air waves or via cable or satellite. HDTV is a special type of digital TV that is combined with the amazing sound quality of Dolby Digital Surround sound. However for this to work the TV stations and consumers need to upgrade their technology. The main selling point behind HDTV is the resolution of the pictures that are displayed; just imagine 720 or 1080 lines compared to the 625 we are used to here in the UK.
The three main formats that HDTV’s use are:
– 720p which runs at 1289×720 pixels and is progressive
– 1080i which runs at 1920×1080 pixels and is interlaced
– 1080p which runs at 1920×1080 pixels and is progressive
If you are wondering what the main difference is between progressive and interlaced displays are don’t worry.
Interlaced: the screen refreshes every other line at one refresh of the image and then the next refresh will update the remaining lines to complete the picture. There are 30 frames per second meaning that current screens only show half the frame every sixtieth of a second. This is only a problem is larger displays and can’t be noticed on smaller screens.
Progressive: This method allows for the picture to be updated in one go with all lines being refreshed. This allows for a much smoother picture.
Are there any actually HDTV stations yet?
There are actually HDTV stations broadcasting around the clock but mainly in America. The first ever station to broadcast HDTV was WRAL-HD. The main governing body behind HDTV has stated that all stations must be able to transmit digital TV by 2007 in America. The digital deadline in the UK is now set for 2012
This means that consumers will have to buy new equipment to be able to receive digital TV, which is already happening in the UK with the vast uptake of digital set-top boxes and satellite receivers. It is up to the broadcasters to decide which format they choose to broadcast digital TV in, they may sacrifice quality and opt for 720p so they can transmit for channels. Even so a HDTV will still have about 10 times more picture detail than a normal TV. Look at the difference between an analogue and a high definition picture below.
Currently in the UK HDTV has not been launched although the digital revolution has started. The announcement of satellite services such a Sky saying that will start broadcasting HDTV channels early in 2006 has started the ball rolling in what will be a interesting technological conversion to follow. The range of new TV sets will probably be released to coincide with this rollout. The advances in picture and sound quality will be well worth the initial financial cost and prices will only come down as more people jump on the high definition bandwagon.
The new Xbox360 will support HD output providing you have a HD-Ready TV, you will have had to have brought your TV within the last six months for this feature to be included on some of the top end plasma and LCD sets. The preferred connection between the Xbox 360 and a HD-Ready TV will be a HDMI cable. This makes sure that sound and video are transferred in perfect sync. Microsoft will only release a HDMI cable when there is enough demand for one which hopefully won’t be too long. You can download HD demos from the Microsoft high definition showcase website at http://www.wmvhd.com Check out the HD Xbox 360 screenshot below.