Long Range Ultrasonic Sensor

Discussion in 'General Electronics Chat' started by HallMark, Sep 19, 2013.

  1. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Hello Friends,

    I am looking for Ultrasonic sensor which can be used to measure distance atleast 12-15 meter with good accuracy.

    Can anybody suggest me such sensor?
     
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I have never used this sensor, but I have used similar (smaller range) sensors from this manufacturer, and I rate their performance as "excellent."
    http://migatron.com/products/rps-3000/rps-3000.htm

    Now, before you go and buy that, look at the pretty pictures. This thing is suggested as a sensor to sense tank level, a pretty big target. Are you trying to sense tank level? or distance to a wall/other large target? or distance to a mosquito flying on the other side of a warehouse?
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    and define "good accuracy"
     
  4. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Thank you Buddy,
    Yes there is one tank and I want to measure it's level. It may contain some chemical or water.
     
  5. sirch2

    Well-Known Member

    Jan 21, 2013
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    I recently built an ultrasonic distance measuring unit that could do better than 13m from transmitter to receiver with an array of 7 standard cheap ultrasonic transducers. Upping the gain on the receive amplifier and taking a bit more care over tuning the transmitter resonant circuit may well get a lot further. Accuracy, when compensated for temperature, is around 10 to 20mm.

    Is it 15m to the fluid or 15m round trip - i.e. 7.5m above the low level?
     
  6. HallMark

    Thread Starter Member

    Apr 3, 2011
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    It is 15m to the fluid. But round trip around 22m is also fine. Can you give me some more detail about the setup you have done?
     
  7. sirch2

    Well-Known Member

    Jan 21, 2013
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    I've been meaning to get the write-up on line for a while now so I will try to do that tonight. But in a nutshell the transmitter is 7 transducers (6 in a hexagon, 1 one in the centre) to form a basic beam-forming array. This is driven as a series LC circuit by a 40kHz square wave from an arduino.

    The reciever is a two stage op-amp based amplifier with a gain of about 20 per stage followed by a schmitt trigger to drive an interrupt on the arduino and record the time taken.

    One thing you could do is use a similar array on the receiver side to get more gain.
     
  8. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Which sensor you have used in this array?
     
  9. HallMark

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    Apr 3, 2011
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    Use of array will result into higher Beamwidth right?
     
  10. sirch2

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    Jan 21, 2013
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    I used sensors similar to this one (only I bought direct from china via ebay)
    http://www.mouser.com/catalog/specsheets/KT-400242.pdf

    And no, the effect of the array is to make the beam narrower. The datasheet above shows a 60° beamwidth at -6dB, I can't remember the exact figure but my array gave something under 10° IIRC. Google Beam Forming, it's more often used in radio antenna etc. but work with any waves. Basically there is constructive and destructive interference and if you get the spacing right you can get constructive interference down the bore-sight of the array.

    Like I said, I'll try to get some details posted tonight and link to it from here.
     
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  11. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Thanks for the more information. Waiting for your post. :)
     
  12. sirch2

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    Jan 21, 2013
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    strantor likes this.
  13. THE_RB

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    Feb 11, 2008
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    You're not worried about the "chemical or water" in the tank and condensation etc destroying your ultrasonic transducers? The entire inside of that tank will be wet and dripping.

    Why not use an immersible capacitance sensor or even an external capacitance sensor on the tank (if the tank is non-metallic)?
     
  14. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Tank is metallic. And I am planning to make casing for sensor so Chemical or water is not going to effect it.
     
  15. THE_RB

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    Feb 11, 2008
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    How are you going to put the ultrasonic sensor in a sealed case? The diaphrams need to be uncovered, so the ends of the transducers need to be open.

    A metal tank does not rule out capacitive sensing, it might even make it easier. :)
     
  16. sirch2

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    Jan 21, 2013
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    THE_RB and HallMark like this.
  17. GopherT

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    Nov 23, 2012
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    These are fairly common in the chemical/oil/process industries. I don't know why one would build one rather than buy one. They have intrinsically safe versions for use with solvents. Corrosion resistant versions for use with acids. Web browser addressable versions for plug-and-play. Life is so easy today.

    http://www2.emersonprocess.com/en-u...tters/3100-series-ultrasonic/Pages/index.aspx
     
  18. HallMark

    Thread Starter Member

    Apr 3, 2011
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    Readymade is too much expensive and I want to use for personal use so looking for some cheaper solution. :)
     
  19. HallMark

    Thread Starter Member

    Apr 3, 2011
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  20. THE_RB

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    Feb 11, 2008
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    Exactly, I thought you had already decided to build an array out of 7 cheap sensors as was previously discussed. THAT would be hard to seal airtight.
     
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