You can still detect range with a modulating IR.  Also, if you have each robot
at a different modulating frequency, you can detect which robot you are
chaseing by what frequency it is at.

Nathan Hendler wrote:

> Can IR detection work if the IR source isn't modulated?  In most IR
> robotics circuits (obsticle avoidance) I see, the circuit uses a shart
> reciever, and modulates the IR source.  Cool enough, except...
>
> My goal is to have more than one small robots that can chase or avoid
> eachother (or interact, or whatever).  One IR emitter on the back, one or
> two ir detectors on the front.  An 8pin PIC controlling the whole thing.
> If these robots are always indoors, do I need to worry about modulating
> the IR?  I was hoping to be able to get away with two IR detectors each
> connected to an A/D port, so the PIC's could determine which detector is
> detecting more IR.  Has anyone seen this done, know of a circuit or done
> it themsleves?
>
> I guess what I'm looking for is some knowledgeable advice on hooking up IR
> detectors to A/D ports on a PIC.  I'm concerned about getting good 0-255
> readings in different indoor lighting conditions.  Or mores specificaly,
> I'm concerned about only getting 0 or 255 on both detectors except in very
> specific lighting.
>
> I'd also like to have an array of IR detectors hooked up to a PIC for A/D
> conversion and then have the values sent to a computer via serial.  Seems
> simple enough.  Anyone have any advice on multiplexing A/D lines?  I'd
> like to have 8 rows of 8 IR detectors, so...  I'm not really sure how to
> do that.
>
> Thanks,
> Nathan Hendler