Subject:
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Re: tracking an IR beacon
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 7 Dec 1997 09:52:39 GMT
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Original-From:
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David Kott <dakott@alpha.delta!stopspam!.edu>
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Viewed:
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940 times
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On Fri, 5 Dec 1997, Jeff Keyzer wrote:
> Hello all -
>
>
> My goal:
> I'm trying to determine the feasibility of tracking an IR source with my
> Handy Board. My initial scheme calls for using two IR detectors (the ones
> with all the internal filters, etc, to provide a clean 5V output upon
> detection of a 38-40khz IR signal.) Those two detectors would be situated
> 3-4 inches apart, on top of an RC servo and sonar transducer. (To be used
> for ranging.) If the IR source delivers a 40khz signal with another square
> wave modulated on top of it (much like the 6.270 board's 100/125 Hz IR
> beacon routines), the difference in phase between the received signals at
> each detector should give information about where the IR beacon is, with
> respect to a position centered between the detectors where there will be no
> phase difference. (The phase difference would be caused by a difference in
> the length of the path the IR signal takes to get to each detector.)
Hmmmmmmmmmm... welllll.. if you are planning to use the GPUI series or
equiv. as your detectors.. I think you may run into problems with
attempting to detect critical time information about the modulated
waverform. Namely, and I'm no expert on bandpass filters or PLL's
buuuuuuuuuuuuuuuuuuut, it DOES take time for the receivers to "lock" onto
a given frequency. This may obfuscate the very information you are
attempting to quantitize. You may wish to, at this early juncture, use a
different receiver... one that doesn't force to trust these little magic
cubes.. and any liberties they may be taking with your signal.
-d
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Message has 1 Reply:
 | | Re: tracking an IR beacon
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| (...) I confirm what David is saying! Once i worked on some kind of beacon using an PLL to find its frequency (we used a lm567) and it couldn't work properly due to the response time of the PLL. An alternate solution was to replace the PLL by a (...) (27 years ago, 7-Dec-97, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | tracking an IR beacon
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| Hello all - My goal: I'm trying to determine the feasibility of tracking an IR source with my Handy Board. My initial scheme calls for using two IR detectors (the ones with all the internal filters, etc, to provide a clean 5V output upon detection (...) (27 years ago, 6-Dec-97, to lugnet.robotics.handyboard)
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