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Motorola HDD200 |
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| 1. | What is an interlaced image? |
NTSC are made up of two interlaced fields. Interlacing was necessary in the 1950s to make it possible for the television sets of the day to refresh the screen 30 times per second without there being a noticeable strobe or flicker on the monitors. Breaking the image into an odd
and even field, drawing one field first, then drawing the other, was the solution to this strobe. Because of backward compatibility, broadcast images are to this day still limited by these interlaced signals
Let's look at this a little closer. Every NTSC television system uses 525 vertical scanning lines. That is, there are 525 horizontal lines stacked vertically on top of each other, comprising the total TV image. To avoid confusion, you must remember that horizontal resolution, the specification listed by virtually all television manufacturers, is a measure of how many individual dots can be resolved along one of the horizontal scanning lines. Horizontal resolution equates to how sharp the image can be rendered; vertical resolution is a fixed facet of the television system. Every 1/60-second your television set shows you one half of the vertical scanning lines, called a field. during the first 1/60 second your set will display lines 1,3,5,7,etc...During the second 1/60-second your set will display lines 2,4,6,8,etc...Therefore, every 1/30 second your television shows you one complete frame. One complete frame is composed of two fields, which are interlaced. |
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| 2. | What is Line Doubling? |
Line Doubling is a term that describes a television image that has had each field converted to a complete frame. That is, the television is showing you 60 frames per second instead of 30 frames. This increase in picture information causes the image to look more film-like, with
richer colors, lower video "noise" and less graininess. Of course, most televisions are designed to show only 30 frames/second, so line-doubling an image on a standard television is impossible. The television simply cannot display the image at this increased speed.
High definition televisions, and sets designed for use with progressive scan DVD players are designed specifically to show more picture information. Like a computer monitor, HDTV sets are capable of progressive scan (non-interlaced) images. Progressive scan inputs on a set are usually found in the form of component video connections (YPbPr) or RGBH+V connections. These are the same connections used to hook up an external HDTV device, like the HDD200. |
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| 3. | How do I hook up my HDD200 to use it as a Line Doubler? |
The connections are exactly the same as would be used to connect the HDD200 to view a HDTV program broadcast via 4DTV. The YPbPr or RGB+V outputs (item 9 and 10) are connected to the component or red-green-blue inputs of your high-definition television monitor using three to
five high quality 75 ohm video cables as needed. The HSI connector (item 1) is connected to the MMAF (Multi-Media Access Port) output of your 4DTV receiver.
On a typical installation you would be instructed to hook the standard definition output of your 4DTV receiver to the S-Video and/or composite input of the HDD200 (item 7 and 8).
In the illustration above: 1. High Speed Interface In order for the HDD200 to process signals from all the components connected to your home theater system, connect the monitor output of your audio/video receiver to the composite and S-Video inputs of the HDD200. connect the composite and/or S-Video outputs of your 4DTV receiver to one of the standard definition inputs of your a/v receiver. The other inputs to your receiver can be your VCR, video game console, laser disc player, DVD player or other standard definition video device. Not, whenever the 4DTV is not on a high definition channel (or when it is off) the input to the HDD200 will be whatever device you selected on your a/v receiver. When you want to watch a high definition broadcast from your 4DTV receiver, just tune to it. The HDD200 will automatically switch from line-doubled standard definition to its internally decoded high definition signal. |
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| 4. | What kind of television monitor do I need to use the HDD200 as a Line Doubler? |
You can use the HDD200 as a line doubler with any 16:9 television which supports 480 progressive scan images or a higher format. This means that every 16:9 HDTV is a potential candidate, whether a tube type set or rear projection. If your set does not use RGBH+V or YPbPr
connections (RCA, Proscan and Mitsubishi sets) you may be able to use an RGBHV-to-SVGA "breakaway" cable (not included with the HDD200). If the standard definition image fed to the HDD200 is of the 4:3 format variety typical of standard definition programming, the HDD200's output will be
"shadowboxed" 16:9. That is, it will show a 4:3 image centered in the 16:9 picture area. You will have black bars to the left and right of the television image. This is normal, and desirable, as it prevents geometric distortion.
If you have an HDTV "ready" monitor that has a 4:3 display area, the HDD200 will display its image as a letterboxed 16:9 image with black bars across the top and bottom of the picture, just like a high definition broadcast. Of course, if you now line-double a standard definition image it will "shadowbox" that image inside of the already "letterboxed" HD image and you will end up with a very clear and clean image which occupies only the center third of your television screen. As you can imagine, this is probably not a great way to watch programming! We don't recommend the use of the HDD200 as a line doubler with 4:3 "HDTV-Ready" sets. |
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