CurtPalme.com Home Theater Forum

radar · Joined: 05 Dec 2007 Posts: 72 Location: Sydney, Australia

Hi There,

I have a 1001qm and when I'm looking at the screen and nodding my head (may sound crazy, but if someone is offering XXX, one may nod vigorously).... I notice the scan lines. If I keep my head still, its not there. Does that mean the bandwith (Mhz) or the interlacing of the machine is slow enough for the scan lines to be visible in this condition? So if I upgraded to a better CRT, should I go for a higher bandwith or higher resolution (or both)? Or does this have nothing to do with the scan lines being visible (under these conditions)?

XXX means beer by the way!

**AnalogRocks** · Posted: Wed Dec 05, 2007 5:16 am Post subject:

Yep nothing like 8 foot wide por....beer. Very Happy

**Curt Palme** · Posted: Wed Dec 05, 2007 5:44 am Post subject:

This explains it:

http://www.curtpalme.com/CRTPrimer_14.shtm

David_Web · Joined: 02 May 2007 Posts: 418 Location: Sweden

I take it the signal is interlaced and that would indeed be the cause of it.
As interlaced is only sending half the lines at once it will draw the other part black (in reality it will just skip the line)
When nodding your point of view will change so that the drawn lines will sit ontop of each other with a black line between them.
In effect it won't really matter how fast you update the screen but how fast you move your head. However at higher frequencies it might be harder to notice it.

It has not really anything to do with the "sweet spot" of the pj but how interlacing works.

dbaisey · Posted: Thu Dec 06, 2007 6:32 pm Post subject:

Isn't the 1001g a video only projector? If so you will need more XXX or upgrade to something with a higher kHz value and bandwidth.
1080I is 33 kHz and 720P is 45 kHz. Yours is 15.75 kHz 480I (video). Something in the 65 kHz range is about right. Doug

Tinman · Posted: Thu Dec 06, 2007 8:18 pm Post subject:

Don't nodd your head!! Very Happy

Marc

**kal** · Posted: Thu Dec 06, 2007 8:56 pm Post subject:

Exactly right: Motion makes scanlines stand out more.

By either moving your head fast, or stuff on screen moving fast, your brain sees the scanlines more as the scalines are the one thing that DON'T move. They stay still. So your brain focuses on those.

Kal

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

This guy has a hell of a time with that problem.

<obscure 5-year-old pop culture reference>

radar · Joined: 05 Dec 2007 Posts: 72 Location: Sydney, Australia

Thanks folks... that was really helpful. So, when I'm on the couch with the girlfriend and she asks if I want any xxx, I nod vigorously and I suppose I'd forget about the scan lines anyway. Alternative two is to upgrade and get one which has a faster scan rate/frequency and agree with the girlfriend slooooowly!