Underwater GPS

[Herk_Man]

Thought just came to me (as they often do when I remove my government-mind-ray-blocking tinfoil hat) regarding underwater navigation.

Is anyone out there attempting to produce an underwater GPS unit? Is it feasible? Can a signal be received underwater?

And before I get flamed, I'm as old-school as anyone but technology will always progress and I think this would not be a bad enhancement. PADI just revised their open water certification and removed dive tables from the training. Now they train computers.

How long, if it is feasible, before underwater navigation will be presented on a screen similar to a dive computer?



HM

 

[paddler3d]

I'm sure it will show up here, but there was a product released at DEMA that is basically what you describe. You wear a computer which looks like a DC. You hand a transponder off a boat which somehow give you your location in lat/long and show where your buddies are, assuming they are using the same units, as well as you can save waypoints, and it had some basic topo maps.

Search DEMA 2009 and see what you come up with.

Found a link to the product that caused a lot of brew ha ha at DEMA this year...

http://www.shbinstruments.com/Navimate.htm

 

[Herk_Man]

Looks like it's on the way. Very cool product. I noticed on the high-res image that there were two divers displayed. I wonder if that means that it also tracks the position of other divers wearing the same equipment? Another great safety enhancement for diving, as long as you still do the work necessary to be competent with compass nav, in the event of GPS failure.

HM

 

[NETim]

No way a GPS signal is going to penetrate into water in any way close enough to be usable. As alluded to above, a link using a very low frequency signal from a topside GPS receiver system appears to be workable.

I wonder though about the distance over which a connection could be maintained. Low freq signals have a devilishly long wavelength which means long antennas for best reception.

Interesting engineering problem.

 

[muddiver]

Interesting, but it's not true GPS. The signals from the satalites will not penitrate water. It has to be an acustic system that trys to guess your location realitive to the transponder on the boat and translates that to cordinates realative to the GPS position of the transponder.

My second question would be, where did the detailed data come from to make the "topo maps" of the dive site? Even the U.S. Navy doesn't have detailed charts of the coast line in less than 100 feet of water that would be useful to a diver. Most charts are for shipping and are only detailed enought to prevent running aground.

 

[romanmw]

I don't think it would work. We got one for our mother in law and the book for it says that if the window has a certain amount of tint in may not receive correctly. I can't imagine them working underwater. Not yet anyway

 

[SCUBASailor]

This is not my area of expertise, but radio frequency does not propagate through water very far. That's why wireless integrated computers need to be near the transmitter. Can anyone post a link to a website for a manufacturer of this device? I think the only option for communication for the submerged device would be sonar, and that's not not an effective solution, as far as I am aware. It would be interesting to find out how the manufacturer is addressing this, if it truly does work. A breakthrough like this would make the inventor very wealthy.

 

[cbrich]

My second question would be, where did the detailed data come from to make the "topo maps" of the dive site? Even the U.S. Navy doesn't have detailed charts of the coast line in less than 100 feet of water that would be useful to a diver. Most charts are for shipping and are only detailed enought to prevent running aground.

Good question, some lake have good topo maps but that's it, nothing that has location of sunken boats or such. I wonder if a lot of the artifical reefs have detailed maps of them.

Lower Colorado Authority in Austin, TX has a somewhat detailed map of Lake Travis, but that's because the Applied Research Laborities is experimenting with clasified sonar systems used for the next generation ships and subs. I attended a seminar about Lake Travis a while back ago, and a few guys from the Labority their showing off some of the high resolution sonar scans they have, but nobody was able to get a copy of it.

 

[ba_hiker]

Interesting, but it's not true GPS. The signals from the satalites will not penitrate water. It has to be an acustic system that trys to guess your location realitive to the transponder on the boat and translates that to cordinates realative to the GPS position of the transponder.

My second question would be, where did the detailed data come from to make the "topo maps" of the dive site? Even the U.S. Navy doesn't have detailed charts of the coast line in less than 100 feet of water that would be useful to a diver. Most charts are for shipping and are only detailed enought to prevent running aground.

There was an airborne ocean floor mapping project a few yeras ago which mapped a few areas. they used a pair of lasers at different frequencies to map shallow waters.
The differing frequencies allowd them to measure depths through tens of feet of water (to a max of just over 100 or so depending on water clarity) several high res maps were generated, mostly in the florida area as i recall...

 

[Desert_Diver]

According to the write ups, the underwater units work in the acoustic frequency range. What is the effect of the thermocline? Does the bearing and range data get distorted by the thermocline? Can the unit work in the presence of a thermocline? Can thermal "ducting" distort range and bearing info?

Has anyone asked a company rep at DEMA any of these questions?

Thanks,

Art