Subject:
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Re: IR Collision avoidance
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 3 Mar 1997 16:11:19 GMT
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Original-From:
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rabbit <g-webb@students.uiuc.edu/AvoidSpam/>
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Viewed:
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1949 times
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At any point are you making an effort to detect your 40kHz IR
signal? If you use the sharp IR detector to receive your 40kHz signal
you are going to get an initial burst when the thing first turns on and
then it will average out to zero just like you said. However solution is
not to get rid of the 40kHz carrier. I am assuming that the sharp is
actually adjusting the gain of the signal it gets rather than the
frequency. The reason you see the signal 'average out' is because it is
a periodic signal; it is on as often as it is off. You are not going to
see much of a signal if you try to read the signal as DC. The point of
making your signal 40kHz is to differentiate it from the background noise
which is spread out over all frequencies, and random bursts are less
likely to be exactly 40kHz. At the receiving end you need some sort of
resonant RLC circuit which resonates at 40kHz or some other kind of
filter to only look for 40kHz signals.
If you said something about this already in your previous letter
my appologies; I only had time to scan over it breifly.
Garth
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Message is in Reply To:
 | | Re: IR Collision avoidance
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| Well, at risk of being branded a heretic, since you've brought up the issue of modulated IR, I'm going to throw out an observation I've made about the Radio Shack IR sensors which several other people on the mailing list have privately disagreed (...) (28 years ago, 3-Mar-97, to lugnet.robotics.handyboard)
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