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Apr 23, 2008 5:04 pm US/Mountain
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CBS4's High Definition Migration Is Under Way
Good Question: How does HD work?
Written for cbs4denver.com by Alan Gionet
DENVER (CBS4) ―
The migration to high definition on CBS4 is a process that started four years ago. It meets a demand for clearer pictures that many viewers are coming to expect.
"There's a big difference. It's interesting to move between a channel in regular and a channel in HD and just see the clarity," said Denise Vega about her family's television watching habits.
But for many people a high definition set is still out of reach. That's not a problem because the change will not mean anyone cannot get CBS4 News. Many of the programs on CBS4 are already available in high definition, such as soap operas, much of prime time programming and sports.
This week, those with high definition cable and satellite hook-ups can get the HD version of the broadcast, says CBS4's director of operations David Layne. But in 5 to 10 days, KCNC will begin using its new transmitter on a new tower.
HD quality will then be available to everyone over the air.
Layne, who's been working on the transition from the start, compares it to the changes in the cell phone industry (from those old clunky, analog cell phones to new digital technology.)
"Our first cell phones were analog and then slowly all cell phones became digital and we got better more pristine audio, we could do a little bit more with our cell phones. Television's the same thing. We're transferring; we're migrating from the analog world to the digital world. In the digital world we can send a lot more information."
That means a wider screen similar to what you see at theatres, rather than the box style shot you've watched on your old television.
It's called the aspect ratio.
"We can give you almost twice as much information. One of the big changes is the screen in 16 x 9 instead of 4 x 3 the old way. What we've discovered is the 16 x 9 movie theater (it's a movie theater style screen) is more pleasing to the eye."
If you have a regular TV set, it will simply cut off the edges of the picture, rather than squishing the wider image, to fit your TV.
High definition also includes more scan lines. Those are the tiny lines across your television (too small to notice) that create the picture using pixels.
For years television broadcasts have used 480 lines of resolution. High definition takes the number of lines up to 1080 lines. The more lines, the smaller they are on the screen. That means more pixels that emit the light of the picture and far more definition.
To get HD you will need an HDTV with a built-in tuner. Not all HDTV's have them.
If you have an HDTV without the tuner, you'll need a box from your cable or satellite provider that feeds your HDTV a high definition signal. Regular TV's (non-HDTV) will not give you the finer HDTV broadcast no matter what you do.
To get the broadcasts from your cable or satellite provider, you'll have to pay extra for HDTV. Or, to receive it over the air, you'll simply have to teach your television or set top box that it's there.
When you first turn your TV or set top box on, it maps where all the channel are.
"And in mapping, that internal mapping, it takes channel 4 digital and channel 4 analog and maps them to a channel 4 position," says Layne.
So nothing changes in our newscasts.
The Channel 4 digital signal actually comes in over channel 35, but frankly you'll never know that, since resetting your television will send it automatically to where it needs to go.
To reset, turn it off.
"Unplug it actually. What happens is that while we'll transmit the HD signal to your home over channel 35, you'll never turn on 35. The first time your TV wakes up, or when you tell it to wake up again, it maps all the channels."
It will put channel 4 on the old channel 4 and right above it will be 4.1, the digital signal.
CBS4 will broadcast more material in HD than stations that went HD earlier, simply because the technology is newer.
"The disadvantage they have is that two or three years later, there's a lot newer technology, there's technology that can move the data and the pictures faster and we can do more with it," says Layne. "It's one thing to do it in the studio and that's a big task. A bigger task in my view is to do HD live from in the field."
CBS4 has equipped some of it's live vehicles with HD technology.
"That clearly will be much different. It'll be a whiter, brighter, better picture because we have leapfrogged in technology where other people are."
(© MMVIII CBS Television Stations, Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)