Bentronics
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Raspberry Pi submarine

Sun Mar 22, 2020 7:51 pm

I'm trying to make a submarine with a Raspberry Pi Zero W and I have a question. How should I connect to the submarine to view through its camera and control it?

I'm fine with pretty any way to do that. I was thinking of using WiFi, but if there's anything better, tell me.

Thanks!

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davidcoton
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Re: Raspberry Pi submarine

Sun Mar 22, 2020 9:20 pm

Good luck trying to get WiFi working underwater.

Previous projects discussed here have used network cables rated for underwater use, and sealed the cable through the hull to withstand the pressure at the expected depth. Suggest searching for earlier posts, I'm just working from memory (with no error checking :lol: )
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dickon
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Re: Raspberry Pi submarine

Sun Mar 22, 2020 9:27 pm

Wifi is 2.4GHz, which is remarkably close to the frequency that microwaves use to heat food. They use that frequency because the H-O bonds in water wobble when subjected to radio waves of that frequency, and in so doing, absorb it and heat up.

Microwaves typically use ~1kW, and AIUI typically attenuates to virtually nothing within ~20mm. Wifi uses considerably less power -- some mW; I forget the details -- which won't last long at all. So yeah, good luck with wifi. Note that Bluetooth also sits in the 2.4GHz band, so forget using that, too.

The Zero W doesn't do 5GHz, but I very much doubt that would work any better.

W. H. Heydt
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Re: Raspberry Pi submarine

Sun Mar 22, 2020 9:39 pm

An optical link might work, but you're likely to have difficulty running it at more than a minimal data rate.

Heater
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Re: Raspberry Pi submarine

Sun Mar 22, 2020 10:57 pm

You can't. WiFi waves won't go through water.

You are going to need a cable to the surface. Perhaps up to a buoy with a WiFi radio and antenna on it.
Memory in C++ is a leaky abstraction .

pcmanbob
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Re: Raspberry Pi submarine

Mon Mar 23, 2020 9:51 am

When you consider that every ROV used in the commercial work for exploration or in the oil industry is tethered with a cable for remote operation/video link and they spend millions of £/$ developing theirs, it should give you a hint as to the way you need to do yours.

If they could get a reliable wireless link to work they would , one of the biggest hazards when operation an ROV is getting the tether line entangled on something .
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Heater
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Re: Raspberry Pi submarine

Mon Mar 23, 2020 10:06 am

Probably wise to have a tether on it anyway. For when your software crashes and it dives to the bottom. Or it gets snagged on something.
Memory in C++ is a leaky abstraction .

Eirikur
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Re: Raspberry Pi submarine

Mon Mar 23, 2020 6:27 pm

I'd use Ethernet cable. You could power over it or use batteries for ballast.

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