Sonic ranging experiment on small scale

Discussion in 'The Projects Forum' started by THE_RB, May 21, 2013.

  1. THE_RB

    Thread Starter AAC Fanatic!

    Feb 11, 2008
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    Hi, I had a bag of matching cheapo electret microphone inserts, and did an experiment on small scale sonic ranging.

    This uses 2 or more mic's to detect where a surface has been "tapped", ie; detects and locates a sonic event.

    Maybe this could be used for special keypads or musical instruments or some other fun application.

    Here's a photo and 'scope capture of the test setup;


    [​IMG]

    [​IMG]


    And for anyone interested in small scale sonic ranging using cheapo hobby level technology the full experiment is here;
    http://www.romanblack.com/SonicRanging/Sonic_Ranging.htm

    :)
     
  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Could this be extended to hand claps in 3d space? Or even to recognize someone talking (not recognize what they are saying). The requirement would be to identify if a louder than background noise occurred in front, to the left or to the right?
     
  3. wayneh

    Expert

    Sep 9, 2010
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    This could be an interesting addition to a game of "Marco Polo" in the pool. You could make a small floating robot that can find victims in the pool by the noise they make. Kids would howl.
     
  4. THE_RB

    Thread Starter AAC Fanatic!

    Feb 11, 2008
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    Sure. Handclaps in a room are a very similar application if you just need the 2D position of the clap.

    Talking would be more difficult I think, due to lower sound levels and more variation in wave shape and phase.

    The experiment used the "pulse" of sonic pressure when something is tapped or clapped, and that pulse has certain reliable characteristics. The pulse helps on a small scale, down to sub-inches or millimetres in ranging.

    For a larger scale application like Wayneh's swimming pool etc it can be done by a high frequency tone "ping" and detecting the received pings with different time of flights.
     
  5. Markd77

    Senior Member

    Sep 7, 2009
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    For the pool, it might be better to just have a few directional mics and head towards the loudest one.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    Speaking of pools, this discussion has me wondering why there are not sensors built into public pools to detect an unmoving, child-sized object in the deep end. I'll guess the answer has to do with liability, for fear that people will expect to rely on the sensor alone and fire the lifeguard. And I guess pools aren't built with deep ends anymore. :(
     
  7. GopherT

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    Nov 23, 2012
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    Don't talk yourself out of a million dollar business opportunity. There are plenty of old pools out there. There are many more home pools that would benefit. Even the shallow end is too deep for toddlers and your idea would help any unattended pool - set when leaving pool and respond when any kid or animal ends up in the pool.

    I am surprised something like this does not already exist - I like the idea.
     
  8. wayneh

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    Sep 9, 2010
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    I wonder if you could mount something in, as part of, the drain. I know pools had to be retrofitted with drains that cannot hold a child on the bottom. Maybe you could even power this thing from water being pulled through a turbine.

    Laser or sonar? Hmmm....
     
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