Two weeks ago we discussed the latest products introduced at this year’s consumer electronics show — to include my favorite topic, 3DTV. A friend wrote: “Great Pete, but how about starting with the basics. Television in the States has gone from analog to something else. The newer TV screens are of a different shape. And during some of the programming, the picture seems a lot sharper. How come?”
The difference between the old-fashioned standard definition (SD) and the new high-definition (HD) television is quite simple if we don’t get too technical. First, SDTV has a more rectangular screen with an aspect ratio of three to four. That means that the heights of the screens, on these older sets, are 75 percent of the width. The newer HDTVs have a wider screen with an aspect ratio of nine to 16, which means that whatever the width of the screen that the height will be 56.25 percent.
Now people want bigger TV screens and if you simply made the screens larger, the old standard definition pictures would look fuzzy. So what has happened is that the HD picture you now look at has roughly five times the resolution (sharpness) of that old SD set. But that means you need to send more dots or lines of information and that takes up more bandwidth.
And there is barely enough bandwidth for example between channels 2 and 5, for these four channels. And if each channel needed five times the bandwidth, there would be no way this could be done using present technology.
But guess what? There is that new technology I’m always talking about. Do you remember those old satellites that only had up to 24 channels on them using that old fashioned analog technology; and how when the signals were converted to the digital technology, the number of channels per satellite changed to several hundred? That’s because with digital technology you can compress the signal and have more than ten times the information in the same amount of bandwidth.
Well, digital is definitely the coming technology and country after country is converting its television, radio and other signals to digital. It hasn’t happened here in Mexico yet, but it will. So if you plan to watch the local channels in HD, make sure that you buy a new HDTV with a tuner that will work for both the digital and analog channels.
If you are interested in purchasing a new HDTV and the above information was helpful, understand that there is much more to learn. Do you want a 720p, 1080i or p? How about the refresh rate and contrast ratio? I recommend that you go to www.cnet.com/hdtv-world/, look part way down on the left hand side of the webpage for the block titled #1 Understand HDTV (HDTV 101, beginners guide), use your mouse to left-click on that block and start reading.
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