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Plasma Hook ups (1 Viewer)

Mike Bledsoe

Stunt Coordinator
Joined
May 24, 2002
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67
I am curious
If you are going to watch NTSC on a plasma tv, I believe you should have a line scaler and when you are not and have a HD signal you should not. What confuses me is,what do you do when switch between the two. Do HD receivers have switches that allow you to change? I would imagine that HD with a line scaler would be over kill.
Please someone with the knowledge help me.
Mike :frowning:
 

Allan Jayne

Senior HTF Member
Joined
Nov 1, 1998
Messages
2,405
Composite and S-video is always interlaced so the HDTV-ready TV uses its built in doubler (de-interlacer) or scaler.
The component video input may be interlaced NTSC, progressive NTSC, or HD, which are three different scan rates. Either there are separate jacks for each kind or the circuits automatically sense which kind it is or there is a manual switch somewhere (it would not be a menu entry becaus until the right selection is made, the screen would show gibberish).
If the TV automatically senses the scan rate, you can feed progressive scan from your DVD player into one A/V receiver component input and HD from your HDTV set top box into another A/V receiver copmponent input and the receiver's component output goes to the TV with no need to unplug things or do anything special each time you choose what you want to watch. Your VCR video can go through an external doubler such as an iScan (think of it as a scaler) and then to a third component input of yhour receiver.
(If you connected the VCR via composite and without an external scaler, you will need in addition a composite cable from the receiver monitor output to a different TV input bank, and when viewing tapes you will need to select Video 2 on your TV if that is where the composite cable went in.)
For consumer video, HD does not require a separate line scaler. But a plasma TV has a fixed number of rows of pixels on its screen and the scan lines of the incoming video must line up with these rows. If the number of scan lines for the incoming video is different, a scaler is used here too and the TV has it built in. Most plasma sets have 480 rows of pixels, the next common number is 720, so 1080i HDTV needs to be scaled.
Video hints:
http://members.aol.com/ajaynejr/video.htm
 

Vince Maskeeper

Senior HTF Member
Joined
Jan 18, 1999
Messages
6,500
If you are going to watch NTSC on a plasma tv, I believe you should have a line scaler and when you are not and have a HD signal you should not. What confuses me is,what do you do when switch between the two. Do HD receivers have switches that allow you to change? I would imagine that HD with a line scaler would be over kill.
Please someone with the knowledge help me.
Mike,

First things first, I want to be clear that the questions you're asking don't only relate to "Plasma" display systems- but are a common concept for any high resolution capible display device. LCD and CRT projection systems that support high scan rates also fall under this information.

The idea is pretty simple- you TV set has the ability to display higher resolution pictures. In most cases, it's designed only to display these higher resolutions. So, when dealing with older NTSC material, it's best to do something to get the resolution up to a point the TV likes.

Most sets have regular composite/component/svideo inputs that support standard NTSC signals. These inputs then use an internal conversion system to double or scale the image to a point the display can better handle. Some people opt for an external scaling device, as the picture quality tends to be a bitt better on higher-end scalers (or even midrange products, as often the internal doubler on TV sets is mediocre).

Now, in terms of switching...
Keep in mind that your TV display doesn't know "what" you're making it do. It simply sees a particular signal and sync rate. If you scale a NTSC signal to 1080i [HDTV resolution]- the set will see the incoming signal as 1080i and display it.

So the answer here is- you simply connect the signal from the doubler/scaler to your set, and supply it with a sync rate the TV can handle. Check your set connections for the number of HI Def inputs it has (inputs that support higher scan rates)-- and if it only has one and you need to connect an outboard scaler/doubler as well as a HDTV tuner box, then you might need a switcher to handle both signals.

As far as scaling a HD signal- this is actually possible- but the problem is that the majority of TV sets available couldn't handle the scan rate to make the image work. So, while it is possible to double a 1080i signal, you TV could never keep up with the rate.

Hope that helps, feel free to post follow-ups to clarify if you still have questions.

-V
 

Vince Maskeeper

Senior HTF Member
Joined
Jan 18, 1999
Messages
6,500
Well, sorta.
You probably won't need to connect any HD signals to the scaler (unless it has a High Def pass through, like some do)-- rather any NTSC signals would go through a scaler and then connect to the HD input on the set, and HD signals (DVHS, HDTuner, PC) would connect directly to the set.
So, you'd have 2 HD signals: one from your HD source (like a HD tuner for example) and one from the Scaler output... some sets only have one HD capable input, so you might need some sort of switching that can handle HD signal.
One slight exception-- if you end up with a DOUBLER for processing NTSC signals instead of a "scaler", this might need to connect to a specific 480p input on the set. Most sets have a "progressive" input designed for progressive DVD players [as they have become popular]- and this input on the set expects a 480p signal, which is what a raw line doubler will provide. Scalers will usually allow you more options of output signal rates- allowing your to tinker to find the sweet spot of the set and the scaler...
So, essentially- what you said above is correct- however it might be more clear to say:
"You connect all NTSC sources to the scaler and adjust the scaler to the scan rate of your tv and the TV syncs to the incoming signal."
Hope that helps.
-Vince
PS: Is that link to your site? Just curious if you have a company that sells these items, yet don't know this stuff. If so, maybe you should give me a job... ;)
 

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