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Under water wireless signal?

Discussion in 'Radio and Wireless' started by lewinskys, Sep 4, 2018.

  1. lewinskys

    lewinskys

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    Aug 23, 2009
    Does a regular Arduino wireless module able to send signals under water? I'd like to be able to control a device in my pool. I am thinking that this isn't possible as water is much denser than air and this would maybe slow the signal changing its frequency and strength.
    Any ideas how this could be done?
     
  2. Hopup

    Hopup

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    Jul 5, 2015
    If its 2.4G module then yes the range is reduced lot. For better penetration in water use modules with low frequency like 900M or even less.
     
  3. hevans1944

    hevans1944 Hop - AC8NS

    3,908
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    Jun 21, 2012
    Is the device in the pool mobile? If not, why not run water-proof cable wiring to control it?

    Electromagnetic waves do not propagate well underwater. That's why the U.S. Navy uses extremely low frequency (ELF) transmitters to communicate (one way only) with deeply submerged and stealthy nuclear submarines. After receiving a message from "home," the sub will generally surface to periscope and external antenna depth to establish two-way communications via satelite links. This isn't necessary, of course, if the received message says, "Launch your ballistic missiles. We are at War."

    You might want to consider other means to communicate with and control your underwater device. Ultrasonic sound waves, or a green laser are two possibilities. What is the range between the underwater device in the pool and the control point outside the pool?
     
    davenn likes this.
  4. WHONOES

    WHONOES

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    May 20, 2017
    Have to agree, ultrasonic's would be the simplest option and could be controlled from you Arduino.
     
  5. Externet

    Externet

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    Aug 24, 2009
    Is the sending emitter of any kind (ultrasonic, light, radio) above water or submerged as the receiver ?

    Submerged...

    Use radio at 100KHz or less. Forget about MHz+.
    Audio... use DTMF. Very long range capable.

    Ultrasonic... should work fine with proper transducers.
    ----> https://duckduckgo.com/?q=ultrasoni...content/uploads/Arduino-Ultrasonic-Sensor.jpg

    Light... A TV remote in a clear sealed bag with a visible or IR emitter should work up to certain distance to a proper photodiode decoder.
    ----> https://duckduckgo.com/?q=ir+detector+module+for+tv&t=canonical&iax=images&ia=images
     
  6. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Problem is, all the inexpensive transducers are made to operate in air. It MAY be possible to "bag" them in mineral oil (or similar relatively inert liquid) and operate them submerged in water. I don't know because I've not tried this. The resonance frequency will surely change, probably becoming lower in frequency because of the increased mass the transducer must "push" against. That is probably the reason most ultrasonic transducers suitable for immersion in water are magnetostrictive instead of piezoelectric: easy to produce (and dissipate) a lot of power with a magnetostrictive transducer (essentially a solenoid with a nickel-rod core). You might be able to re-purpose transducers commonly used for ultrasonic cleaning applications, such as this one.
     
  7. Externet

    Externet

    632
    131
    Aug 24, 2009
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