Salt Water Communications

[Bob Gato]

Most of the fully submersible sub models run in clear swimming pools (my observation) and unfortunately the growing trend is to convert the fresh pool water to salt water to enable electric chlorine manufacture on site-The operational environment is growing even smaller!

[Das Boot]

I live in San Diego and fortunately or unfortunately (depending on how you see it) I am surrounded by salt water. This includes our local RC pond. I just received the Kilo kit from Bob Martin (thank you very much Bob) and wanted to explore ways to communicate in salt water. I came upon this research paper that describes how they developed an acoustic system for RC vehicles that is simple and intuitive using acoustics. IT looks like the form factor could be implemented in RC Submarines and I wanted to get the opinions from the experts on here. In the meantime I plan to run the antenna up through the a snorkel so I can run at periscope depth in the local pond. I have about six months left in my Middle East deployment so have time to work out the problem set :)

Here is the link to the paper
http://robert.katzschmann.eu/wp-cont...015compact.pdf

Thoughts?
Cory

Even the tried and true 75 MHz radios don’t like salt water. Real subs use VLF, Very Long Frequency, to communicate with a base. These receiver antennas are massive. Besides, running in salt water is not advised. Corrosion being the factor. Try these guys. https://sandiegoargonauts.com

[coryhenry]

Apparently the Arduino doesn't have the power for an acoustic system.

http://my.fit.edu/~swood/John%20Clau...al%20Paper.pdf


If you look to OTS solutions, acoustic modems looks like the way to go. With two of these and some programming on your part, you can probably come up with a workable acoustic control system.

https://bluerobotics.com/store/comm-...ms/wl-11003-1/

Great link, $1400x2 is getting closer to doable.

[coryhenry]

Well I just got back some quotes for acoustic transmitters and now I know why they are not used in RC hobbies. Transmitters run in the $7000 range :(

[SteveT44]

Apparently the Arduino doesn't have the power for an acoustic system.

http://my.fit.edu/~swood/John%20Clau...al%20Paper.pdf


If you look to OTS solutions, acoustic modems looks like the way to go. With two of these and some programming on your part, you can probably come up with a workable acoustic control system.

https://bluerobotics.com/store/comm-...ms/wl-11003-1/

[coryhenry]

Check out this robot fish https://www.google.com/url?sa=t&sour...=1594983359058

Funny this is the exact study I referenced in the first post :)

[redboat219]

https://youtu.be/Dy5ZETdaC9k

swims like an injured fish, imagine a shark suddenly gobbling it up.

[Bob Gato]

How freaking cool is that! Its not a far stretch of the imagination to see the controls interfaced with an above surface link. And secondary-the hydraulic propulsion is way cool (good for Sci-fi and future sub models)

[redboat219]

Check out this robot fish https://www.google.com/url?sa=t&sour...=1594983359058

[coryhenry]

You could eliminate the radio and just hook a handheld game controller directly to the arduino.

You are absolutely correct, I just wanted to make a package that could be used with any system and keep it comfortable for the normal RC user, not always a gamer :)

[redboat219]

You could eliminate the radio and just hook a handheld game controller directly to the arduino.

[coryhenry]

This is the architecture I was thinking could work.

[Scott T]

Not sure if this could be done but what if you made a repeater radio that could plug in your radio receiver then translates the received signal and sends it out as 75 hz. You could then buy the latest greatest radio and plug its receiver in the repeater radio. While you are at it add WIFI so you could send commands from a phone. Phones don't show up well in sunshine though.

[redboat219]

Electronics are beyond me but how about a system that uses acoustics? Going back to the IR remote, how about swapping a piezoelectric transducer to the IR diode to send out "pings" which corresponds to control commands. An piezoelectric receiver on the boat listens for the pings

[coryhenry]

I did see some research with laser comms. They do require a sophisticated tracking and aiming mechanism to ensure the transmitter and receiver are always in alignment. The IR systems have a very wide beam so don't really have that problem.