My brother and I are considering designing and building a remotely controlled submarine. As far as experience, I have some knowledge on RC systems, and I am almost done with my General license. My brother hasn't completed his license yet, but shares much of my experience.
The problem we're facing is getting a live video feed/FPV from the craft while under fresh water. We don't need great range, just enough to get down 10-15 feet vertically, maybe (though more would be much better, of course). Our goal is for it to be completely wireless, avoiding having some type of umbilical cord.
The question is, how low frequency can you go so that it is not absorbed, but intelligible enough to maintain (visual) control the craft at as low as around, say, one frame per second? I don't need amazing reaction speed like you'd need with a quadcopter.
Next would be finding what frequencies you can legally transmit this on (I think this would be classified as "remote vehicle control"?), and where to get equipment for it. (We haven't even gotten here yet, but when we do, I'd like it to stay under $500.)
Edit - so far, there are a few options I'm keeping in mind, along with others' advice (I'll accept the answer that I think most resembles the original idea):
- Physical cable
- Surface floating "buoy" antenna
- long antenna to surface (similar to last option)