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Discussion Starter · #1 ·
Hello,


I have seen a DILA demonstrated a few times. Once was in somebodies home theater, and another time was the demonstration of Madrigal's D1 projector at a dealer.


On both projectors, I noticed that you could see noise in the picture. If there is a solid color on the screen, you could see little wavy lines moving through the image. In some ways it almost looked like heat waves, but the pattern was too consistant for that.


Is this present in all DILA projectors, or did I just happen to see two projectors with problems?


Thanks!

Scott
 

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I have also seen this noise but have no explaination for it.


I have also seen a couple of units without this noise so it could be a quality control issue with JVC.




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Alan Gouger

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Scott,


I haven't seen this video noise in either of my D-ILA FPTVs that I've owned, or with other ones that I've seen so far.

Maybe it has something to do with an unclean power source, poor video cables, or maybe internal scaler artifacts with different DVD players.


-Dean.
 

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Discussion Starter · #4 ·
I guess that it could be unclean power (it does look kind of like interferance) but it does not look anything like artifacting of the scalar, especially since it is very visible on solid colors.


The dealer that I saw the demonstration at (Definitive Audio in Bellevue) is fairly high end, but that doesn't mean that their power was the greatest either. They were doing their big HT event where all rooms are packed with gear showing off their best... or worst http://www.avsforum.com/ubb/smile.gif
 

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I had a fair amount of phase noise that I couldn't get rid of until I was able to tweak a hidden scaler parameter. After the adjustment, the projector tracking can be set to entirely eliminate the phase noise - but the proper setting still drifts over time and requires occasional adjustment via the user menu.


I use a desktop pattern of alternating black and white pixels that readily exposes any pixel timing mismatch between the HTPC and the projector.


 

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Quote:
Originally posted by mjws:
I had a fair amount of phase noise that I couldn't get rid of until I was able to tweak a hidden scaler parameter. After the adjustment, the projector tracking can be set to entirely eliminate the phase noise - but the proper setting still drifts over time and requires occasional adjustment via the user menu.
mjws, can you describe how you tweaked the hidden scaler parameter? I also have noticeable phase noise, even after going through the Dilard Tracking and Phase wizard. No phase adjustment seems to be able to COMPLETELY get rid of the noise.


Incidentally, Scott's original description of the noise he saw does sound very much like phase noise.


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Discussion Starter · #7 ·
May I ask what phase noise is?


Although this is unrelated, I'm guessing that if the timing from the source component does not exactly match the pixels on the projector, that you could get into a situation where pixels pop back and forth between adjacent pixels. Is this correct?


The noise that I saw was moving in a vertical direction. You could see waves going up through the picture. I wish that I had my camera with me http://www.avsforum.com/ubb/smile.gif
 

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The scaler (DPC) itself has what I surmise is some kind of PLL implemented in software - this is separate from the PLL VCO stuff that Dilard grants access to via the Advanced Settings in the Geometry Wizard.


Anyway, there is a DPC Gain setting that is normally zero. Setting it to 1 or 2 allows the scaler to fully lock to the pixel clock and ENTIRELY eliminate the phase noise. It makes a tremendous difference - at least in my situation.


I think the best thing would be to drop an email to Mark Hunter and ask him to consider adding "DPC Gain" to the Advanced Settings dialog box. That way I don't have to feel responsible for totally screwing up anyone's expensive projector http://www.avsforum.com/ubb/smile.gif
 

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Quote:
I think the best thing would be to drop an email to Mark Hunter and ask him to consider adding "DPC Gain" to the Advanced Settings dialog box. That way I don't have to feel responsible for totally screwing up anyone's expensive projector.
Good idea. This sounds like a good feature suggestion for the 2.2 release. I have put it on the build list for the release.
 

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Pultzar,


You are correct - for best results - you have to sync the

pixel clock in the PJ and the dot clock in the video card.


They have to be synched both in frequency [ tracking ] and

phase.


Although I doubt that it would be severe enough to jump to

adjacent pixels - it can give you the "waviness" in the

picture.


This is described in Mark Rejhon's FAQ on "pixel perfection"
http://www.avsforum.com/ubb/Forum10/HTML/002952.html


Mark describes the effect of bad tracking / phase adustment,

as "jittering and flickering".


It may also explain why it is seen on some and not all

D-ILAs - you see it when the tracking / phase are out of

adjustment.


Greg
 
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