Subject:
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Re: Homebrew Sonar
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 17 Sep 1997 23:06:50 GMT
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Original-From:
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Chuck McManis <cmcmanis@freeSPAMCAKEgate.net>
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Reply-To:
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CMCMANIS@nomorespamFREEGATE.NET
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Viewed:
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1230 times
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Here's an idea for homebrew sonar that I keep mulling over
but haven't built yet. If anyone builds one of these be sure
and tell me if it doesn't work so I won't :-)
Basically the idea goes like this:
take a signal generator (like the EXAR chip) and configure
it to generate some centerfrequency like 40Khz. Now modulate
the generator using a triangle wave whose period is the same
as the maximum sensing distance (say 32ms for a 32' range)
now feed a receiving transducer through and AGC amplifier
to a PLL. Take the error signal from the PLL and add it to
the input signal to the transmitter. The result will be the
magnitude of the phase difference between the input signal
and the received signal. The phase difference can be sampled
with an A/D for arbitrary precision, the value of the difference
times the speed of sound is the distance.
Normally it would seem to be a lot of hardware but you can now
build a lot of it inside a DSP and that would make it easier to
construct.
--Chuck
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Message is in Reply To:
 | | Re: Homebrew Sonar
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| Check out (URL) There's some basic theory and 6811 assembly code in there for doing time-of-flight stuff with el cheapo 40kHz transducers we got from All Electronics Corp and some homebrew circuitry. Colby --- "King, Terry" wrote: (...) --- end of (...) (27 years ago, 17-Sep-97, to lugnet.robotics.handyboard)
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