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Discussion Starter · #1 ·
Just what is this, and what does it do?

When pj blanking is opened all the way up, I have always had a certain amount of what looks like "background scanning", like the guns aren't shutting all the way off.

Is this because of incorrect front/ back porch settings?

If I start playing with these settings can I hurt my pj?

How do you know when they are set correctly? OR for that matter how do you know when they are set incorrectly?


Kenny
 

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What PJ lets you adjust the front and back porch timing, and yes you can destroy your projector if you don't know what your doing, and there aren't to many people around that probably know much about the timing of the video signals in that area, and I don't think anybody is going to want to help you destroy your PJ.


Pete
 

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Kenny,


have a look here for a laymans FAQ on monitor signal terminology ....

Monitor sync signal FAQ


Using Powerstrip you can custom create timing signals specifically for your monitor or projector. To get a better understanding of how the porch values affect the positioning of the image ( within the raster ) plug a normal multisync monitor into your PC and run Powerstrip. Use the monitors vertical and horizontal height controls to shrink the raster so that it is all contained with the physical screen area. You may need to turn the brightness up a touch. As you add and subtract porch values the image will shift left or right ( or up and down ) within the raster. There are certain minimum porch values needed depending upon the scan frequency being shown. This allows the electronics to stabilize the beam before you start drawing the actual image.


There is obviously a lot more to this that what I have briefly described and a search with google will bring up more indepth discussion.


Cheers!


Russ
 

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Discussion Starter · #4 ·
Thanks for that link Benny, very helpful.

At this time, the Ampro I'm working with has plenty of Raster showing on either side of the image, but none showing at the top and bottom of the image.

It seems to me as though I could decrease the "front porch" (horizonal sync impulse) to lessen the amount of unused raster on the sides...and increase the "back porch" (vertical sync impulse) to increase the vertical active time and give me a little raster above and below the image.

Does this seem logical???
 
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