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Re: OT:New TV purchase?
#110134 09/07/05 02:37 PM
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That sounds suspicious. I assume he is talking about a de-interlacer since SD signals all come across interlaced but are often de-interlaced so they can be displayed at 480p rather than 480i.

To the best of my knowledge the de-interlacers in modern HD TVs are actually pretty darned good. I was under the impression that was one of the high points of modern TV design. He is right that de-interlacers are expensive but they are the heart of modern consumer electronics (de-interlacer is the same hardware as the upconvertor) and I don't think too many corners are being cut there.

EDIT -- I just re-read your original post where you said that the image was blurry... that *could* be an artifact of de-interlacing... do you know if you can set the TV into a different mode so that it actually displays an interlaced image when looking at standard TV ? That would bypass the de-interlacer and give you a "normal" TV picture if the de-interlacer is the problem.

Last edited by bridgman; 09/07/05 02:43 PM.

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Re: OT:New TV purchase?
#110135 09/07/05 03:23 PM
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Also one thing to think about is that you don't want to stretch non-HD programming as that can accent any defects that you are seeing. So make sure SD programming has black bars on the sides of 16:9 display.

Re: OT:New TV purchase?
#110136 09/07/05 06:18 PM
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In reply to:

He said this is because modern HD tvs lack the proper "interlacer."


As Bridgey ( ) pointed out, if I understand what the tech is saying correctly, that would be a deinterlacer.

And if your TV is showing an interlaced signal on a progressive scanned screen, believe me, it wouldn't be a bit fuzzy/blocky/soft, any horizontal motion would show interlacing artifacts.

See these images (rendered 'em out quick for illustration)

In each case, the gear is moving right to left, the stopwatch bottom to top of frame.

Image #1 - this is what a SD NTSC signal would look like on a progressive scan monitor without any sort of deinterlacing before scaling (to 720P give or take).

Image #2 - same image, but deinterlaced (top field bicubic) prior to scaling. Note jaggies on the edges. Top field is the "earlier" field, so the positions have moved.

Image #3 - here's the same image (again, top field shown) rendered out in native 720p, no sclaing, no interlacing.

Hope that help illustrate.

Bren R.

Re: OT:New TV purchase?
#110137 09/07/05 07:15 PM
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I just did a bit more reading on this... looks like some deinterlacers will blur the image to cover artifacts when running in "bob" mode (essentially de-interlacing a field at a time, displaying each line twice), and will fall back to "bob" mode unless they can recognize patterns in the incoming video. A DVD player can get cues from flags in the MPEG stream but I don't think those flags get passed through into the video.

I'm starting to wonder if it was such a good idea to get the higher end Sony CRT (with progressive scan and deinterlacing) for my parents if they are going to be mostly watching standard NTSC TV programs. I hadn't realized how many artifacts are generated when de-interlacing normal video...

Last edited by bridgman; 09/07/05 07:18 PM.

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Re: OT:New TV purchase?
#110138 09/07/05 07:30 PM
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In reply to:

I'm starting to wonder if it was such a good idea to get the higher end Sony CRT (with progressive scan and deinterlacing) for my parents if they are going to be mostly watching standard NTSC TV programs.


Well, any time you're mismatching a signal there will be issues... even an interlaced image going to a monitor at non-standard resolution that is interlaced... the interlacing of the source is always every second line to a field (say for ease of math it's 480 lines).. and the interlacing of a CRT will be every second line line to a field (say a 960 line resolution)... so each of the interlace fields of a SD source will cover two lines on an interlaced CRT (upper and lower fields, which are displayed 1/60th of a second apart) unless some further manipulation is done to make up for it.

There is no easy answer. There is no good solution. That's why I still have a SD television.

Bren R.

Re: OT:New TV purchase?
#110139 09/07/05 07:53 PM
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My fuzzy TV is on both Sony SD crt and Sony HD Plasma on the 2-13 channels with the problem Bren described earlier. Is there a home fix since the cable company won't respond?

Re: OT:New TV purchase?
#110140 09/07/05 08:36 PM
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Gee, this place is a wealth of technical information I wouldn't even begin to understand. I am glad I picked up the hi-def receiver since it has dolby digital audio. That is way .

Re: OT:New TV purchase?
#110141 09/08/05 06:31 AM
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Bug - is this your own house?

If so, you can replace any of the old coax (anything not marked, or rated for less than 900MHz) which will get rid of the rolloff on the high frequencies, you should then have too strong a signal uniformly across the board.

RadShack has this, an infinitely variable pad but I'm not a huge fan of having a sweep pot left in a signal path.

A bit of guess and check with these would be more my style... try maybe 10dB, if the ghosting goes away but the channels get snowy, it's too much, try a 6 or 3dB.

(Not pushing any of these site/distributors, just giving you an idea what to look for, both also pass DC in case you have cable internet or for use with satellite systems)

There are also slope compensators that would make up for your cable loss without replacing it, but trying to find one that matches your loss pattern would be mind-boggling.

Bren R.

Re: OT:New TV purchase?
#110142 09/08/05 07:00 AM
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Oh, a few more pearls of wisdom about cable/CATV while I'm on the subject.

GROUNDING BLOCK = GOOD. Remember to ground your cable as it enters your house. Floating DC current on it makes for all sorts of bad stuff. I'm like a canary for stray voltage - maybe all the Pepsi I drink, I'm the only person I know that can get a yelp-worthy shock off of CATV.

Satellite users should probably invest in some high bandwidth coax - I'm a bit weak on my satellite theory, but I believe, since the major players bundle gigahertz-plus coax with the dish, there's probably a good reason. No need for boutique stuff.

Schwartzen-what? Terminate all unused cable runs with 75ohm terminators, especially if using unpowered splitters, it balances the signal level. Do NOT terminate powered DistAmps (distribution amplifiers)!!!

Bren R.

Re: OT:New TV purchase?
#110143 09/08/05 02:07 PM
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I can get shocked off of CATV. I always figured it was just my imagination, though.


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