On Thu, 13 Sep 2001, Dmitry Alexeyev wrote:
> Hello.
>
> I have BT878 card and external multiplexer with several monochrome cameras
> connected to it. If one camera is off ( blank screen ), bt878
> automaticaly increases brightness, so I can see nothing on frames from
> other cameras.
> How can i turn off AGC ?
>
> Dmitry
>
Seems your problem is the multiplexer not the AGC.
If properly clamped to black level AGC will probably
no longer interfere.
This of course requires minimum expertise to
clamp the multiplexer input to black level
when camera is off (using a capacitor, resistor
or combination, after analysing the input circuit).
However, if you have such ability it must be
pretty simple and "safe" once it's just a simple
clamping. (clamping activation via camera power)
But with today VLSI "closed source" trend things
simple like this may even be impossible. :-(
Open source hardware too will be great....
schematics, information access... or better
put the closed hard crap in trash together
with the closed source soft too. ;)
No need to mess the AGC that seems to be not
the cause but just the symptom of a floating
input signal.
Hope this helps.
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