I am working on a project to build a remotely controlled underwater robot. The max depth the robot has to dive is 40cm. I tested the 2.4GHz RC transmitter and receiver and it could work only up to 15cm below water surface, even though not very stable. I googled a lot, but didn't find any proper transmitter and receiver set with minimum 4 channels, in frequency range of less than 100MHz or at 433MHz. Would anyone please suggest where I can find one or how I can assemble one with off-the-shelf modules?

  • $\begingroup$ why do you need multiple channels? $\endgroup$
    – jsotola
    Oct 8 '19 at 16:59
  • $\begingroup$ Welcome to Robotics roTor-roTor, but I'm afraid that shopping questions really aren't a good fit for a stack exchange site. We prefer practical, answerable questions based on actual problems that you face. Take a look at How to Ask and tour for more information on how stack exchange works, and the Robotics question checklist for details of how to write a good question. $\endgroup$
    – Mark Booth
    Oct 9 '19 at 10:14
  • $\begingroup$ In general it is better ask How do I solve this problem? than What do I need to buy to solve my problem in this way? as you may preclude answers providing better solutions. In this case, given the existing answer which suggests what you want to do is not possible, you may want to ask a new question (linking to this one) which asks how you can communicate with your auv. $\endgroup$
    – Mark Booth
    Oct 9 '19 at 10:17
  • 1
    $\begingroup$ @MarkBooth Ok. I will rephrase my question to meet the criteria. Thanks for the tip. $\endgroup$ Oct 9 '19 at 10:53
  • $\begingroup$ Thanks for your new question and I hope that you manage to find a solution to your problem. $\endgroup$
    – Mark Booth
    Oct 9 '19 at 11:52

Is the robot going to have an over-the-water antenna?

If not, then electro-magnetic communication is a no-chance under-water, if the water is salty (seas, oceans) or if the distances are long. The underwater communication is usually done with sound (acoustic waves) - which can travel huge distances, thanks to the higher density of water, compared to air.

Here you can find some more information.

More to-the-point information here:

At 1 megahertz the skin effect depth in wet soil is about 5.0 m, in seawater it's about 0.25 m.

It means that in sea water the EM waves will travel no more than 25cm, at 1MHz. The higher the frequency, the shallower the depth.

More formulas here.

Why EM is not the way: Radio-controlled_submarine, unless you have an aerial antenna for the submarine.

If the water is fresh (no dissolved salts) and if the distances are (relatively) short, then the project might have a chance, depending on the specific details.


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