Underwater Communication
John R.
Posts: 1,376
I must admit, I haven't googled yet.
I am contemplating constructing a submersible "vessel" and using Stamp or SX for control.· I would like to avoide an umbilical.· I do not anticipate a fully autonomous vehicle, and will need some communication, both for control, and some reporting of data back (water temp, depth, maybe low res images).
Has anyone done anything with "remote contol" or other "wireless" communications under water?
I'm suspecting that radio is out, and have ruled out ELF due to data transfer rates and a strong desire to avoid a visit by the US Military.· Could this be done with ultrasonics?
Just floating for ideas.
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John R.
8 + 8 = 10
I am contemplating constructing a submersible "vessel" and using Stamp or SX for control.· I would like to avoide an umbilical.· I do not anticipate a fully autonomous vehicle, and will need some communication, both for control, and some reporting of data back (water temp, depth, maybe low res images).
Has anyone done anything with "remote contol" or other "wireless" communications under water?
I'm suspecting that radio is out, and have ruled out ELF due to data transfer rates and a strong desire to avoid a visit by the US Military.· Could this be done with ultrasonics?
Just floating for ideas.
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John R.
8 + 8 = 10
Comments
BasicStamp include DTMF for telephones.
It may carry nicely in water. And, you can easily get a decoder·to·use with a BasicStamp.
Parallax sell thems.
There is also a very reasonable 8-pin DIP audio amplifier that can drive a 5watt speaker [noparse][[/noparse]quite a bit of ballast].
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Post Edited (Kramer) : 12/14/2005 3:22:14 PM GMT
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·1+1=10
All you said is true, but it is not "sound", it is a extremly low frequency RF wave thats used... And ELF is not being used any more, all the wires have been pulled on the antenna lines. The main transmitter site is south-southwest of Clam Lake, WI... I have spent a lot of time up there hunting and fishing... The reason that area was picked has more to do with the geologic formation found in the area.
Actually, sound itself travels a long way under water. If I was to controll a RUV, I would use a teathered fiber optic cable, with(out?) power.
To use ELF, one would need some very long wires, sound would be better, at a low baud rate, with a frequency PL for transmition, and detection...
I would think that a pair of depth finders could be hacked for use as comunications devices.
Bob N9LVU
Post Edited (Robert Kubichek) : 12/14/2005 5:19:17 PM GMT
For reference, my target dept is somewhere between 100 and possibly 200 feet. I would forsee the "mother ship" (OK, boat) being fairly close. I wouldn't plan on trying travel the whole lake without the mother ship trailing along to some extent.
Currently this is in an early design and research stage.
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John R.
8 + 8 = 10
Use an underwater speaker as a transmitter and an underwater mic as a detector. You'll quickly see what kind of range is available at some normal audio frequencies. Then, you can better decide which direction to go.
Regards
I really would like to avoid an umbilical, but am concerned about what sound would do to the very critters (fish and others) that I'd be trying to observe.· I also don't know how they would react to an umbilical, much less the vessel itself.
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John R.
8 + 8 = 10
but you may want to power the device from the surface.
If you have to have wires, it is just as easy to control the main thrust of power from the surface as batteries really weigh down a smaller unit.
Nuts and Volts ran an article [noparse][[/noparse]I believe last year] where a teacher used submersible bilge pump motors and their blades to power direction and lift. The whole thing was more of an exo-skelton than a sub. The frame of plastic tubing provided enough flotation to offset the equipment.
And it allows for a very adaptible platform that can include a video camera or whatever else you want to include.
Very simple and low tech, but you could start there and easily go higher.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
I've also seen voice communications for SCUBA, but haven't had a chance to check out what technology is used yet.· A complete set, with masks, helmet, regulator, etc. is under $1,000, so the comms cant be terribly expensive (OK, I'm delusional).
I suspect I will end up with a umbilical, as much as I'd like to not have it.· The·lake the family cottage is on·is darn near 100' deep (one hole is at LEAST 90' deep), and two others at 85'+.· That's a lot of tether to get tangled up.· I am inclined not to run power through it.· I'd want to keep the weight of the umbilical down, as this is just another problem to work with in terms of boyancy managment.· (I guess I could find the right size sealed sections of tubing to use as "baloons" to hold the tether at neutral boyancy, and then it wouldn't matter...)
I like the idea of a test bed using something like bilge pumps and tubing.· Neat way to do some real life testing.
As this is Wisconsin, and I'm not about to test under the ice (interesting thoughts after the thing is proven), I have some time to explore options...
Thanks for the ideas, and keep them coming.
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John R.
8 + 8 = 10
The submersible that first viewed the Titanic had one. Obviously the unconditional retrieval and the power supply are primary issued.
Fiberoptics pretty much give you enough bandwidth [noparse][[/noparse]and without EMI problems] that sonic communications are not required.
Of course, if you want to communicate between two submersibles, the use of sonic communication might provide some benefits [noparse][[/noparse]indicate distance and location as well as being a data carrier].
DIY Sonar is quite appealing too.
If you go to a commerical fishing supply [noparse][[/noparse]saltwater trolling for salmon and tuna] they can easily provide you with the gear for a nearly unbreakable umbilical. You need stainless steel trolling line and a very simple handwound spool that is made to outfit small commerical fishing boats. Alterantively, nylon monofilament comes in fairly high strengths.
I image the Great Lakes have similar commerical fisheries and supply the equipment and stainless steel cable.
The bildge pump motors were in an egg shape housing and seemed to have been removed from the actual pump. They merely drove a prop.
I suspect there are better and more efficent drive setups. It seems that was the key to keeping the cost down as DIY sealed motor units are difficult to develop and advertised units are not cheap either.
I suspect you could alternatively consider an electric trolling outboat, but it seems a bit large and has a 90 degree shift in the drive axis. I suspect that you would have to remove that.
You can always add more flotation in the form of plastic two liter pop bottles or household bleach bottles. The prototypes were being used in a swimming pool. That would be the easiest to observe design flaws.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
The final product will probably have a stainless shell (we make stainless steel pressure vessels at my "day job"), and will likely use the drive heads from the trolling motors.
I may go with the bilge pumps for a prototype to play with both tethered and non-tethered communication. Like a couple other projects I'm playing with, some of the fun may be in pursuing things that are not practical, but learning is most of the fun. (Edison didn't fail all those times, he was learning how not to make a light bulb.) I may try the bilge motors (and they make "cartridge" assemblies with just the motors) as both a drive for a prop, and also with the normal housing as a "water jet" propulsion system. Building a prop with a kort (spelling?) may also be something to try.
The whole concept of a low cost prototype is making the project much more desireable to the other "partners" involved (wife and other family at the lake). We tried one of the commercial cameras, but there was no control, and the lighting was poor (at best). The prototype will not get down where we want to go, but will provide the proof that further investment is worth it (or not).
If we get to a the final product, it will be impressive. Even at 100' deep, the pressures do "interesting" things to the structural requirements of the shell and other components. We'd probably opt for designing it for 200'.
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John R.
8 + 8 = 10