Patent Filed for Underwater GPS

Matthew Sparkes writes "GPS doesn't work underwater, as the signal cannot reach the satellite from a submersible, but researchers have now patented an add-on to the system that could provide GPS navigation for submarines. A base station is tethered to the sea bed at a known depth and GPS location. A submersible anywhere in the area sends out a sonar pulse to which the base station replies with a signal, giving a GPS position and depth as well as the bearing angle from which the submersible's request arrived. The submersible then uses its own depth, which is easily measured, plus the round trip pulse time and the bearing angle sent by the base, to calculate its own position."

Re:Great!

[Anonymous Coward]

I imagine that it would be used as a supplement to traditional submarine navigation methods. Submariners could check in with it very occasionally in order to correct any minor deviations and measure accuracy.

Great

[drinkypoo]

Just another way to bombard marine life with Sonar. Can we please get out of this mentality that convinces us that using active sonar all day is a great idea?

All your GPS base...

[Wiseazz]

...are been moved 10 meters south.

Nice thing about satellites is that they're unaffected by earthquakes and giant squid... but whoever implements this is probably smarter than I am so I won't worry about it.

deserves a patent

[hey]

Seems to me that this is the kind of unique idea that deserves a patent.
Unlike most software patents.

Re:Which way do those signals go?

[Anonymous Coward]

Little nit pick ... GPS signals go from the satellite to the receiver not the other way around.

I don't think this is nit-picking. It's a rather fundamental point to how GPS works.

Re:Great!

[Anonymous Coward]

Hate to bring it up, but if this ever did catch on, just think about all the noise traffic this will cause underwater. Its already been shown the current levels of human caused noise are the cause for various animal beaching, id hate to think what this new system might do.

Where's the "GPS"?

[snarkbot]

"A base station is tethered to the sea bed at a known depth and GPS location." Why does it have to be a "GPS" location? Once the depth and location are known, why is GPS needed at all for this system? (This is a serious question -- I'm wondering if I'm missing something about the setup described.)

Unless the base station is 1) going to move; 2) close enough to the surface to receive GPS signals; and 3) powerful enough in transmission/reception to communicate with submarines, I'm just not sure what the "GPS" aspect is for.

-snarkbot

Re:Great!

[atommota]

This isn't the cold war anymore - most of our subs probably operate loud and proud most of the time.

Regardless if this is the Cold War or not, there is no way our subs are broadcasting their position. We wouldn't be spending millions to develop anechoic coatings and other sound controlling materials for these boats just so we can tell the world where we are. In addition, IIRC, sub patrol routes to this day are not known to anyone except the captain in the sub. They are given a very general patrol patrol area and cruise it as they see fit.

Re:This is not GPS!

[guibaby]

I am not sure how you can patent something like this. It is the same thing they have been doing with buoys for 40+ years. I hit a buoy with my radar and it returns a morse code letter on my radar screen. I look on my chart and find the buoy with the right letter. I add that to direction and distance, and I now know where I am. "I have used GPS, I know GPS, Mister sonar thingy you are no GPS."

Also, I am just guessing here. Anyone who drives a sub, and doesn't know where they are, has bigger problems than someone hearing their ping.

Re:Great!

[Anonymous Coward]

Not only can the device can pick up the reflected beam from the submarine, but so could anyone else in the area. This would NEVER be used for US submarines and I'd bet no US submarine would go anywhere near one of these things. I was on submarines for 10 years and we never used active sonar. GPS was used when the mast can be raised as a backup and for verification to ensure all other systems are still agreeing with each other but nothing else. In fact, I don't think we ever used our radar either.

Getting off topic here but...
One of my jobs was a "phone talker" on the bridge during surface transits (dictate communications back and forth between the between the officer of the deck to the control room) and I remember setting up a regular old store bought portable radar system up there just like the fishing boats used. Another thing we did not do was talk to or even acknowledge other boats in the area that tried talking to us over the VHF radio. We were in plain sight of a cruise ship or even yachts. Our off the shelf radar is spinning around and we are listening to people try to talk to us on the radio. Another interesting tidbit, US submarines do not have the hull number or name painted on the side. In the PR photos they might but they are removed shortly after that. Most in port just use signs that hang from the sail. We had to do a medical emergency personal transfer at sea once. Dude left the ship in civilian clothes with bogus orders that contained nothing that referenced what submarine he was just plucked from.

For reference, I was not part of the Sonar or the Nav ET division that ran the radar and the time frame I was on subs ended about 10 years ago so maybe things have changed since then.

Re:Great!

[Anonymous Coward]

'Scuse me. Former nav div ET2(ss), USN here. Fast attacks, 637s and 688s. I can guaran-damn-tee we are NOT operating "loud and proud most of the time."

For those who don't know, subs don't have to breach the surface to get a position fix. Many modern subs have communication arrays built into their primary scope, which allows them to obtain a GPS fix from periscope depth with only one mast out of the water (very small radar signature). Inertial navigation systems are getting better and better, which continues to extend the time between needing a fix. Assuming the area you are in has been mapped before and has a fairly hilly bottom, you can also do bottom contour mapping by taking depth readings using narrow downward-aimed sonar pulses from the fathometer, knowing your speed (distance between the depth readings), plotting your course on a map of the bottom, and playing connect-the-dots.

All of those options are more stealthy a sub and base station trading pings. U.S. subs have been popping through the ice at the north pole for decades... needing an active sonar GPS to fix their position wasn't necessary.

As for civilian subs? The vast majority of those are either tethered to a surface ship (eliminating the need for sonar gps) or have such limited submerged time that it isn't really worth the effort of setting up a base station for them. Also, I'm going to go out on a limb and say most civvy subs have something closer to a "fish finder" for sonar, rather than something capable of measuring exact time between sent ping & returned ping and exact direction necessary for this system to work.