Yeah, use a damn fast comparator.

Don't forget to clamp your video to a fixed reference level (using sync
tip is common) so that changes in average brightness don't shift your
level (most cameras have AC coupled outputs)

You realize that your data rates will be -really- high...

As for using just an inverter to extract sync, the total video signal
spans but 1V, hardly enough to get a reliable sync extraction from
a mere inverter, particularly if it's threshold is 1/2VCC or the .6V
of a TTL gate. You really should use a sync sep chip or an unused
section
of your video threshold comparator for reliable triggering of the
scanning software.

Michael Lapson wrote:
>
> Hi,
>
> I am trying to build a robot that navigates around obstacles, and I want to
> take input from a B/W video camera, probably infrared. I will scan the
> screen, and if a region is dark, i will avoid it (grass reflects infrared
> very well). I will get the sync pulses with an inverter, since the sync is
> negative, the inverter output will be positive during sync.
> Any ideas how to distinguish the, say, +0.8 V of a light area from the, say,
> +0.2 volts of a dark region?
>
> -Mike Lapson
> <lapson25@hotmail.com>

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