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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."
This is great!
How long before lost submarines are meandering up our rivers and streams because the GPS mapping told them this was the way to go?
On a slightly more serious note, no self respecting spy submarine will emit a ping to this service ever. There is no way you would want to give your position away so freely.
liqbase
Little nit pick ... GPS signals go from the satellite to the receiver not the other way around.
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?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
This technology, like GPS, would most likely have military as the initial customer, hence the customer that sets the design. For GPS, a completely passive system was designed so that an asset could calculate where it was without giving out information to nearby enemies that it was there.
The primary customer for something like this would probably also be the military, so I imagine the actual equipment would be passive as well. There's no persuasive reason to make the sensors wait for a query, just have them send out a pulse at regular intervals that contain their location, a precise time stamp, depth and water temperature. This is enough data for a passive submarine to use to calculate position (the depth and temperature affect the propagation of sound waves). There would be imprecision because the speed of sound is variable, of course, but you'd have a system that won't give away the presence of a submarine the way you would if said sub was "pinging" for the info.
Seems to me that this is the kind of unique idea that deserves a patent.
Unlike most software patents.
What is the current mechanism of position-fixing used for subs? Or is it more of the 'traditional' type of navigation where you know where you started, what direction you travelled, how fast and how long?
Subs have highly accurate inertial navigation systems. I've seen one on of the labs at Stanford where they develop the sensors, and it's amazing. It's kind of like a warehouse, with one of those huge 20 or 40 ton cranes. They use the crane to haul large masses around, and the sensors are able to detect the variations in the gravitational field caused by those objects.
On top of that, the navy has all sorts of charts of the sea floor, many of which are probably classified to some degree or other. Subs can use "landmarks" on the sea floor to determine their position. Since highly precise navigation is usually only important in coastal waters, this works pretty well.
Men will do anything to avoid stopping and asking for directions
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
Been there, done that. Only difference is we didn't have GPS, only LORAN. You don't need GPS, you just need a sonar transponder whose location is well-known.
1977, aboard RV Melville (Scripps IO). We drop 3 sonobuoy transponders to the ocean floor in a large triangle (few kilometers per side). We know the approximate locations only, since they were after all dropped. Ship sails around doing research and pinging away; record round trip times to each transponder; invert large number of observations to solve for locations of each transponder relative to each other; within a day we know the relative locations accurate to within a few meters (maybe better, I don't recall); meanwhile ship is recording LORAN locations; the LORAN locations are cross-correlated with the relative transponder locations (which are more accurate); net result is that transponder coordinates now have a geographic reference (xy to lat-long).
Two issues with the GPS version: (1) you need to anchor to ocean bottom and have antenna at surface, therefore you need a lot of cable/wire; (2) the surface GPS (antenna) position is NOT the same as the transponder, since the cable is certainly not going to be perfectly vertical. Maybe you don't need to anchor it, just let it drift, then #1 doesn't matter.
Someone said this sounds eminently patentable. No, I don't think so!
I hate it when people are perjuditial to wheels.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Basically, this has nothing whatsoever to do with the Global Positioning System. It does not use the signal from the GPS satellites. It does not use any kind of GPS receiver.
This is an underwater positioning system using acoustic ranging from a prepositioned devices on the sea floor which has an accurate position. The obvious question is how do you get the position of the base station. This could possibly be done with GPS using a sea surface GPS based bouy, but there is no specifics on this.
Remember, GPS is a PASSIVE system. Nothing is sent to the satellite.
--keith
They probably have inertial guidance. The missiles carried by missile subs definitely have inertial guidance.
Basically the principle of operations is simple. You start at a known position and speed. If you continually integrate your acceleration (readily measurable), you know your instantaneous velocity at any point in time. Integrate that and you have your position at any point in time.
The big advantage of inertial navigation is entirely self contained. It requires neither signals from the outside nor does it send signals to the outside. I suppose the subs can rise to periscope depths every so often to compare their position to GPS.
My late father in law worked on inertial navigation systems for the Apollo program and the Trident Missile program. Remember the Apollo 13 movie, where they're so worried about "gimbel lock" That was the one way you could head the space craft in such a way the gyros could not move freely; once that happened, you didn't know where you were, at least not enough to get the right reentry path that would get you into the atmosphere without burning up or missing the Earth entirely. He worked on those gyros. Later he worked on laser "gyros" that didn't have mechanical parts to lock up.
Once he visited the naval base in Alameda, bring a suitcase sized inertial navigation instrument from Cambridge MA. The device was precse enough to tell him that the naval base was using wrong figures for their geographic position.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
This misconception has caused no end of headaches for one company I used to do consulting work for. The company was outfitting fleets of cement trucks with CDPD tracker modems -- these devices had a fully-featured GPS receiver, and could be configured to transmit latitude and longitude to a specific IP address on a specific port at a specified interval. (Nuts-and-bolts: the data was typically sent as UDP packets, so no guarantee of delivery, and CDPD is an older standard for data transmission over digital cell networks, with a max throughput of maybe 64 kbps.) We had software that would aggregate the GPS data for the entire fleet at a server, and then client software which would talk to the server and show real-time reports on the fleet, as well as determine who was at a job site and how long they were there, etc.
Unlike what another poster stated regarding cell phones, the tracker devices we used did all the GPS processing on-board, so what was sent via UDP was either a NMEA string (easily parsed) or some simple proprietary binary format. We would do further corrections at the server to account for various map books and which USGS survey data they were based off of.
Anyway, the problem we has was the truck drivers and their misconception of how GPS worked. Many of the more paranoid truck drivers (and there were a lot of them) were absolutely convinced that we were beaming personal data about the drivers themselves to GPS satellites, forwarding it to who knows where. Trying to explain to these folks that GPS doesn't work that way only resulted in angry confrontations. When I started working on a badging project so that our client could further track the comings-and-goings of the drivers, the hostility and resistance reached alarming levels, to the point where I almost couldn't get work done.
Then again, the whole reason for the software's existence in the first place was to provide documentary proof of the misconduct of drivers. Things like guys taking half-hour naps in their trucks after finishing a job site, or over-slumping their load of concrete so they can sell some excess concrete to a buddy finishing his driveway... We implemented autmated job-site entry and exit discovery because we found that giving drivers a set of pushbuttons to signal when they were starting or stopping a job was just a recipe for abuse. (Funny enough, we kept the pushbuttons to see just how big the discrepancies were between when drivers said they were working and when the GPS claimed they were working. It was eye-opening.)
The drivers were unionized in most cases, so a high standard of proof had to be met. I'm sure that contributed to the air of hostility. But it's also true that many drivers were using fake credentials (many being undocumented immigrants), so the paranoia over a potential loss of privacy and transmission of personal data to a "big bird in the sky" wasn't just because people were worried about getting caught napping on company time.
Not mentioning the names of any companies (nor any specific geographic place names) to avoid legal hassles.
100 comments and nobody's asked whether this is a submarine patent yet? Come on, guys! You must be working or something.
I can explanate how to administrate your network. You must configurate and segmentate it, so it can computate.
This thing is not GPS. It is sonar ranging that just happens to also includes the GPS locations of the bouys to help give a true position. Doing sonar positioning requires that you know where the bouys are and GPS provides a very good way of doing this.
Engineering is the art of compromise.