Re: OSC and unity gain buffer
- From: "Joel Koltner" <zapwireDASHgroups@xxxxxxxxx>
- Date: Thu, 10 Apr 2008 13:56:51 -0700
"eeaj2002" <eeaj2002@xxxxxxxxx> wrote in message
news:2f48edc0-cacb-4c94-b704-8a5572a4d93b@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I wrote a simple program that generate a monochrome NTSC signal. I
connected this signal to one of the eye glasses which take the NTSC
signal but nothing was displayed. When I connected my signal to the
DVD player and I fed the output of DVD player into the eye glasses
then it displayed fine. I am assuming the reason for not displaying
is the color burst that is missing
This is highly unlikely to be the problem; I don't think I've ever encountered
a monitor that couldn't handle a regular old (RS-170) black and white signal.
This
why I was trying to see if I can sum the 3.472MHz signal with my NTSC
signal and see if I can display my signal on the eye glasses.
This won't work...
1) The colorburst frequency is 3.579545MHz or somesuch -- but definitely not
3.472MHz.
2) It's a color *burst*, not a color *sub-carrier*. Take a look at the timing
of a color video signal and you'll see it's only present during one of the
"porch" after the sync pulse on each line. (Perhaps you know to do this and I
just misunderstood what you wrote?)
Have you tried feeding your signal into a regular old TV with a composite
video input?
Can you take a picture of a 'scope shot to show us what your timing looks
like? Last time I was writing software to directly generate video, getting
all the timing correct took plenty of time. To begin with you might want to
just generate lines of video (containing horizontal sync) but skip vertical
sync -- if you generate each line the same, the fact that the frame is
"rolling" won't matter.
Note that unfortunately the newer and hence "smarter" a TV is, the less useful
it'll tend to be for debugging since it'll want to, e.g., just give you a blue
screen when it doesn't "like" your video signal.
---Joel
.
- References:
- OSC and unity gain buffer
- From: eeaj2002
- Re: OSC and unity gain buffer
- From: Tim Wescott
- Re: OSC and unity gain buffer
- From: Joel Koltner
- Re: OSC and unity gain buffer
- From: eeaj2002
- OSC and unity gain buffer
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