Subject:
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IR for bots
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 20 Mar 1997 17:36:00 GMT
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Original-From:
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King, Terry <TERRY.KING@ihatespamFMR.COM>
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Viewed:
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2398 times
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Hello everyone,
My thinking (albeit limited), has been that simply driving an IR LED
with ac (ie:40Khz) as opposed to static dc, is enough to discriminate it
from other frequencies like 60 Hz. or whatever. Then, when the detector
picks up sufficient IR being reflected back to it, theTTL output is fed
to a port where the HB program responds accordingly.
Is this the typical usage?
Or is it necessary to inject another frequency on the 40 Khz that can be
decoded? Then the output of the decoder (like a 567) is read by the HB.
I understand that tone encoding allows for multiple tasks on one
carrier, But my main interest here is for object avoidance.
Thanks for any help,
Terry King
Terry.King@fmr.com
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Message has 2 Replies:
 | | Re: IR for bots
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| (...) Our robot worked well with a dual 555 timer. 38KHz for the IR and combined with a 500 Hz square wave. When the square wave was high, 38K was on, making it a 50% duty cycle transmission. As I understand the receiver circuitry, it was tuned to (...) (28 years ago, 28-Mar-97, to lugnet.robotics.handyboard)
| | | Re: IR for bots
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| (...) If you don't modulate the signal you run the risk of having another 40kHz signal (a.k.a. remoth control) trigger the reciever. If you modulate it and look only for you modulation code, then the chances of a stray signal are minimal. I have (...) (28 years ago, 28-Mar-97, to lugnet.robotics.handyboard)
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