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Any reasonable priced (sub 20$/100) ways to directly measure indoors velocities between around 0.1 and 15m/s?

Its main purpose would be to reduce speed drift for a 9DOF device (acc/gyro,magnetometer), so I believe only 1D will do.

Now since it's for indoor use, a GPS won't help. I assume this could be done measuring RF/ultrasonic doppler shift, but I don't know how this is measured, nor have I found dedicated chips to do it.

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  • \$\begingroup\$ Shopping questions are not allowed on Stack Exchange; however, this question seems like a very good question to be asking. It would be helpful if you were to reword your question such that you say what it is you are trying to make and ask for help with it. \$\endgroup\$ – Kellenjb Aug 2 '11 at 13:13
  • \$\begingroup\$ @Kellennjb - noted. I've reworded it slightly. Though does no shopping question mean I can't specify what price range I'm after? \$\endgroup\$ – Imbrondir Aug 2 '11 at 21:28
  • \$\begingroup\$ Price is very important for most projects so it is fully reasonable to say you have a certain price point that you are trying to obtain. \$\endgroup\$ – Kellenjb Aug 2 '11 at 22:06
  • \$\begingroup\$ RF Doppler shift is tough.. You need ADCs that would cost an arm and a leg. Ultrasonic is easier but still not that easy. Good luck and let us know if you find something, I am particularly interested in ultrasonic. \$\endgroup\$ – Frank Aug 3 '11 at 5:01
  • \$\begingroup\$ @Frank - the shifts in question - between 7 Hz and 1 KHz for a 10.5 GHz signal - are in the range where you could sample them nicely with an inexpensive audio ADC. \$\endgroup\$ – Chris Stratton Aug 3 '11 at 21:30
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I suspect that a Gunnplexer as used in Police RADARs and in door openers prior to PIR's taking over would do what you want. Output is Doppler difference of go + motion affected return signal.

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A few examples:

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