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Sonic data transmission? Answered

This is just an idle thought, but I was reading a couple of ROV builds, and the one thing they all have in common is a tether - it's a fact of the world that very little in the way of radio signal can penetrate water.

So...

Could you send control signals to an ROV via sound or ultrasound?  Could beeps and clicks carry enough data, far enough, and clearly enough, to control an ROV?

Even more fun, how much data could come back? Sensor readings? Images?

Just throwing it out there for you to toy with, but it would be fun to have genuinely-remote control for this class of robot.


Discussions

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nazmo76

3 years ago

Audio communication between electronic device has been made (eg: old personal computers used audio tape to save programs or those 56k modems talked by sound on the phone line to get and send data) and is still (eg: clap switches, voice commands, ...).

Doing so to send commands or data may not be a great idea underwater, it will propagate faster than in air (1500m/s opposed to 340m/s in air) but slower than electromagnetic signals and you would need some kind of underwater transciever/receiver and batteries, it would be exposed to underwater noises if not filtered and I don't know about the needed transmission power.

For me the simplest way stays a cable (or fiberoptics but a battery will be needed as well).

How much data, if it's just a ALL/NOTHING communication, IDK but I think a few hundreds/thousands of bits per second

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3DPlaneLiner

3 years ago

I believe military submarines have been or are still using VLF EM comms systems, in the range of 200Hz. It needs extremely long land based antenna's - hey, suddenly I realize those powerlines hanging there could be used for something like that?. Maybe sound is extremely eco-unfriendly and should be avoided at all cost. What remains are light, gravitational modulation techniques or paranormal communication. The two latter being respectively difficult and maybe impossible, I would go for a light modulation solution. Distance could be a problem though due to fast absorption of light in -clean- water. The tether in ROV's is there for a reason. Thousands of people might have wrapped their head around this problem...

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gmoon

3 years ago

Interesting thought. Wiki says frequencies between 10Hz and 1mHz are do-able. I wonder if old-school telephone modems could be adapted to use with a transducer (hydrophone) and amplifiers / filters?

Ultrasonic frequencies would be better, no doubt, for the sake of fish and other sea life. Some (substantial) evidence points towards military sonar being a factor in whale and dolphin beaching. If wiki is correct, and dolphin / cetacean hearing range encompasses 5 to 50kHz, that seems to eliminate the bandwidth that would be easiest to work with...