Testing a Video Signal
in [Design]
|
From: Mike Warren on 20 Jan 2010 19:09 Phil Allison wrote: >** You already have your evidence. > >The PCI video cards do not work with the monitors you need them to work >with. > >Therefore, they are " unfit for the purpose intended " as the TPA says. > >Even if you had a figure for the burst frequency error - it would not >prove >you case any better than the evidence of people's eyes. At this stage I'm hoping that the error can be corrected by an update to the firmware as I can't find any other cards with S-Video or composite outputs. Everything has HDMI only. If I had another source, I'd not have even bothered going as far as I have. -- - Mike
From: Mark on 20 Jan 2010 22:02 On Jan 20, 7:09 pm, "Mike Warren" <miwa-not-this-...(a)or-this- csas.net.au> wrote: > Phil Allison wrote: > >** You already have your evidence. > > >The PCI video cards do not work with the monitors you need them to work > >with. > > >Therefore, they are " unfit for the purpose intended " as the TPA says. > > >Even if you had a figure for the burst frequency error - it would not > >prove > >you case any better than the evidence of people's eyes. > > At this stage I'm hoping that the error can be corrected by an update to the > firmware as I can't find any other cards with S-Video or composite outputs. > Everything has HDMI only. If I had another source, I'd not have even > bothered > going as far as I have. > > -- > - Mike On any quality video gear the H and V and burst ARE phase locked together to minimize dot crawl and other artifacts. Its true that, they don't HAVE TO BE phase locked and it's true that they are not phase locked in consumer grade VCRs but on a computer video board they probably are. Do you see see more then one clock ref on that board, if not then the H and V and color are phase locked. Look at the block diagram of a sync generator. If you can't measure the burst error, then measure the H error. good luck.. Mark
From: Mike Warren on 20 Jan 2010 22:46 Mark wrote: >Do you see see more then one clock ref on that board, if not then the >H and V and color are phase locked. This is a video graphics processor running (I guess) at somewhere between 200 and 500MHz. There is only one external clock, a 27.0MHz crystal. I expect that is only be being used as a reference for a number of PLLs inside the chip, but I don't actually know anything about what happens inside the chip. It's all just guesses. The only thing I do /know/ for sure is that it is not doing what it's supposed to, and another brand of card which appears to have been built from the same reference design works fine. >If you can't measure the burst error, then measure the H error. As I posted a few hours ago, I can not measure any difference in the H-sync, but do see a very slight difference in the colour burst frequency. -- - Mike
From: Mike Warren on 20 Jan 2010 23:07 Phil Allison wrote: >I am NOT telling you what you to do - only pointing out what >measurement >method would likely work. Just for fun I added 5pF in parallel to one of the caps on the crystal and now all three of my monitors have colour. I guess doing that can be a last resort, since it only takes a few seconds, but it's certainly not an ideal situation. -- - Mike
From: Phil Allison on 20 Jan 2010 23:13
"Mike Warren" > Phil Allison wrote: > >>I am NOT telling you what you to do - only pointing out what >>measurement method would likely work. > > Just for fun I added 5pF in parallel to one of the caps on the crystal and > now all three of my monitors have colour. > > I guess doing that can be a last resort, since it only takes a few > seconds, > but it's certainly not an ideal situation. ** Guess that proves the point about the colour burst frequency being off - beyond all possible doubt. Tweaking the PCI card's crystal was suggested by ME to YOU just over THREE days ago. Rub, rub rub ..... ..... Phil |