Underwater GPS

[rcain1]

Of my 11years in the Army as a 31U I worked with PLGR AN/PSN-11 It is a GPS, the first GPS and we regularly used 100foot ant cables.


I have a Garmin 12XL with an external antenna. The current antenna cable length is about 8-9' long. I daresay that the resistance of an antenna cable 55' long would preclude the transmission of the data to the hand-held unit by existing antennae.

In order for the antenna to overcome the inherent resistance of the coaxial cable, it would have to generate an amplified signal.

So, that's what ya have. An amplified surface located antenna sending the acquired signals to the encapsulated, submerged GPS unit.[/QUOTE]

 

[armyscuba]

GPS does work underwater..but that's classifed..SORRY..That's how I find things underwater with accuracy...

 

[armyscuba]

GARMIN does mfg the GPS for the U.S. Navy that is UNCLASSIFIED...

 

[zboss]

Most Garmin GPS units have this weatherproofing standard. I would be extremely wary of floating one on the surface however. Besides, I think the submerged waterproofing measure assumes that external power/data ports are not in use and plugged up. You'd need these open in order to say, run some sort of data screen on a submerged tether.

lasted about 2 seconds once it hit the water and it was the "water/weather proof" model.

 

[The Kraken]

Hey, Armyscuba, what type of unit is it? Is it TO&E for the army or is it also available for the civilian market?

 

[tiswango]

Any ideas of cost? I am guessing it will be out of the current budget of a conservation team, but who knows??
By the way, yes… towing a float is a bit of a pain, for those of you who haven't done it before, but I guess sometimes it is necessary. We were quite isolated, so it was just one more safety method.

Someone already quotes Wades Page for taking underwater GPS. The whole set up will cost less than $300. Wade developed the system for lobster hunting North of West Palm Beach where you hit a small ledge for bugs or nothing for sand.

As discussed the problem is the difference between where the GPS is floating on the flag and where the diver actually is. The GPS numbers on the flag can be corrected to account for the divers using good ole fashioned math. For us techies, Wade made a spreadsheet to do it for you.

Below is a pic of a map of a shore dive off Fort Lauderdale Florida. The two vertical lines are the first and second reef lines. The other is a pic of the site.

Below is line to the PBCRRT maps page.

PBCRRT Maps Page

The PBCRRT is a volunteer dive team and will teach any interested diver how to do this for free!

 

[rmediver2002]

GPS does work underwater..but that's classifed..SORRY..That's how I find things underwater with accuracy...

Your not really saying your on some secret SCUBA team that uses a classified underwater GPS are you?

 

[rmediver2002]

Hey, Armyscuba, what type of unit is it? Is it TO&E for the army or is it also available for the civilian market?

It is possible to establish a position through triangulation with a secondary receiver. You would have a series of GPS or known position buoys that could triangulate the divers position on the bottom.

There is a system known as the Cobra-Tac on the market now that is able to track divers location by entering the water at a known point (GPS coordinate). The unit tracks the divers depth and movements to calculate the current position, this technology is not classified but is pretty costly... (going from memory, between $15,000 and $20,000)

It is available from RJE technologies.
http://www.rjeint.com/default.htm



I am afraid statements like "it is classified" or on another thread "trained to kill" are pretty typical of posers and not at all typical of trained proffesionals especially on a public forum...

Don't try and pretend your something your not, be proud of the contributions you are making!

 

[The Kraken]

The positional error caused by the difference between the diver's location and the location of the GPS antenna, for the most part, is going to be so small that it will be positionally insignificant. This is assuming that the antenna is being towed on a float. All one has to do is to put enough tension on the up line to the float to pull it over one's location.
Current GPS's, even the little hand held units, are accurate to about 1 meter since the DOD removed the signal degradation from the transmitters.

 

[zboss]

All,

The problem is simple. All we need is a Ring Laser Gyro for IRS (Inertial Reference System) input, and a GPS (Global Positioning System) to update it when we do surface. The B-777 has three of these systems linked in a "voting logic" set-up. This is why we can be over a thousand miles out in the South Pacific and look down to see an aircraft directly below us, and another one directly above us. (Doesn't happen that way often, but it does happen!)

Now, what we need is some genius to shrink one of these systems, reduce the power requirements to battery power, AND make it affordable to divers! (It would take a genius!!) Any takers???

Cheers!! BJD :anakinpod

I think I saw that as a downloadable video from the Do-It-Yourself channel... right after the model airplane do-it-yourself video.