Forgot your password?
typodupeerror
Communications Patents

Patent Filed for Underwater GPS 236

Posted by ScuttleMonkey
from the under-achievements dept.
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This discussion has been archived. No new comments can be posted.

Patent Filed for Underwater GPS

Comments Filter:
  • Great! (Score:5, Funny)

    by LiquidCoooled (634315) on Monday March 12, 2007 @03:50PM (#18321341) Homepage Journal
    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.
    • Re: (Score:2, Insightful)

      by 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.
      • Re: (Score:3, Insightful)

        by 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
    • Re:Great! (Score:4, Interesting)

      by hotdiggitydawg (881316) on Monday March 12, 2007 @04:03PM (#18321565)

      How long before lost submarines are meandering up our rivers and streams because the GPS mapping told them this was the way to go?
      Depends... if the beacon has been moved due to the tectonic plates shifting, well... GPS will probably be obsolete by then.

      But if it's been moved by a seismic event (earthquake, volcano, etc) or a bunch of cheeky kids (aka. "terrorists") or even a large marine mammal, well, all bets are off...
    • Re:Great! (Score:4, Interesting)

      by Anonymous Coward on Monday March 12, 2007 @04:07PM (#18321639)
      I work on a system that measures the noise output from submarines as used fot validation when the navy purchases subs, and checking for objects that might need repair because they are causing noise on the outside of the sub. During the runs to get these measurements they bolt on a 1 to 8 second pinger so that we know where in the water to look. If we had exact GPS positioning, it would be fucking outstanding. But this won't really help with that, because what this bouy does to locate the sub relative to itself has got to be the exact same thing we do already to locate the boat (and its not that great. esp if the propeller is between the phones and the pinger)
    • Re:Great! (Score:4, Funny)

      by MrShaggy (683273) <chris,anderson&hush,com> on Monday March 12, 2007 @04:14PM (#18321749) Journal
      One ping and one ping only..

      one ping to rule the world.

    • On a slightly more serious note, no self respecting spy submarine will emit a ping to this service ever.
      Maybe not, but it will tell me where I am when my boat sinks!
    • "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." Not all submursibles are submarines. Think underwater research. And even submarines often operate in non-espionage missions; remember all the stories about sub sonar killing whales? This isn't the cold war anymore - most of our subs probably operate loud and proud most of the time.
      • But research subs always have a tender ship above them that could send the GPS signal to them. They wouldn't need this.
      • Re: (Score:2, Insightful)

        by atommota (1024887)

        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.

        • by nasch (598556)

          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.

          The fact that our military submarines are equipped with active sonar indicates that they probably use it sometimes. Navigating in and out of ports, for example. This would be one more use for those times when stealth is not important, plus as mention

    • ... 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.

      Yarr girl, better you surface to get a proper fix!

  • by goofy183 (451746) <eric.dalquistNO@SPAMgmail.com> on Monday March 12, 2007 @03:53PM (#18321389) Homepage
    Little nit pick ... GPS signals go from the satellite to the receiver not the other way around.
    • Re: (Score:2, Funny)

      by Radon360 (951529)
      Darn...I think you just ruined this guy's patent.
    • This is not GPS! (Score:5, Informative)

      by EmbeddedJanitor (597831) on Monday March 12, 2007 @05:12PM (#18322617)
      I didn't RTFA (that's cheating), but the summary is a crock.

      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.

      • Re: (Score:2, Insightful)

        by guibaby (192136)
        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 th
  • hmm (Score:2, Interesting)

    A submersible anywhere in the area sends out a sonar pulse to which the base station replies with a signal,

    So instead of being available to anyone who can get the signal its only available to those who can communicate with it. This will probably limit the number of positioning systems that can be used at one time. I hope they will make provisions for emergency uses of the system.
  • Great (Score:5, Insightful)

    by drinkypoo (153816) <martin.espinoza@gmail.com> on Monday March 12, 2007 @03:56PM (#18321437) Homepage Journal
    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?
    • by peragrin (659227)
      i will get out of using sonar, the day someone comes up with something better.

      It is the only thing we have for deep water wireless comms, and sensors radio waves don't propagate well. Lasers also don't work very well. Sonar is the best we have. It has been refined so it is not nearly as bad as it was. The Navy has been experimenting with higher power levels to increase resolution. That's where the animal suffering comes in.

      Earn your billion dollars and find another way. I personally like microwaves.
      • Hey! Nuclear subs dont need air or fuel but their crews need food.
        Fish is a good option especially if its already cooked and ready to eat. ;)
      • by sumdumass (711423)
        I thought microwave had problems penetrating saltwater (err water for that matter).
    • humans perpetrating the ocean ... all your oceans belong to us!

      I wonder if they military think-tanks would like it, to have a sound blasted every x seconds towards their house/bedroom?
      • Per your argument, it would have to be sea creatures blasting this sound.

        When whales and dolphins have the means to fight back (depleted uranium shells, subs) then I'll start to be worried. Until then, it's primate rule.
    • 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?
      How else are we to slay sharks with frickin' laser beams attached to their heads?
    • Sending out active sonar in a military context is pretty stupid.

      Although I have not heard of this being done, it could make a lot of sense to use spread spectrum sonar, for ranging anyway. Spread spectrum allows you to get far better signal to noise ratios meaning you can work with far lower signal power (for example, GPS receivers use this to cope with signal strengths that are below thermnal noise). This could give you active sonar without being too obvious to the enemy and without messing up the whales.

      • by drinkypoo (153816)

        Well, ANY active sonar is too obvious to the enemy. I don't want to be excessively paranoid, but remember that "caterpillar" drive from The Hunt for Red October? I realize that was just a movie, but quite a few years ago a Japanese company demonstrated a caterpillar drive on a small surface craft. It was not very efficient, but that was in the public sector years ago. I'm betting that we're using those already. Anyway, rant aside, the sonar systems in submarines can actually identify known patterns of subm

        • A GPS-like spread spectrum signal just looks a lot like noise unless you are able to "de-spread" it, for which you need to know the pseudo-random numbers employed. The Red October signal was easy to detect because it was repetitive and thus very easy to "decode" and the bursts were relatively high energy.

          For long psuedorandom number sequences you could potentially reduce power by a factor of 1000 or so. This stuff could look like white noise, so if the signal levels can be held low enough then it will be ve

          • by drinkypoo (153816)
            The thing is that it will still look a lot like noise that's not supposed to be there. You might not be able to identify it but you'll know where it is.
    • Without further comment, I think it's worth pointing out the recent case of Cetaceans v. Bush [answers.com] on this topic. (386 F.3d 1169 (9th Cir. 2004)) The court ruled that the world's dolphins do not have standing to sue.
    • by suv4x4 (956391)
      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?

      There isn't a "mentality that convinces us that using active sonar all day is a great idea".

      There's an actual use for running sonar all day long, and people use it.

      If sharks, whales and whatever can emit signals to confuse our sonars in return, more power to them. But otherwise, the weaker should adapt. It's how evolution works and we're part of it.

      Tha
      • by drinkypoo (153816)

        If sharks, whales and whatever can emit signals to confuse our sonars in return, more power to them. But otherwise, the weaker should adapt. It's how evolution works and we're part of it.

        So if I meet you, I should fucking strangle you. If you can adapt and get out of it, then you can live. Otherwise, you should just choke because you're weaker.

        That said, although we bring more damage to the environment, we're also those with most research knowledge and organization created to protect it. Who knows, may

        • by suv4x4 (956391)
          So if I meet you, I should fucking strangle you. If you can adapt and get out of it, then you can live. Otherwise, you should just choke because you're weaker.

          Are people randomly mounting sonars hundreds of times more powerful than needed, and used for absolutely nothing, but "proving a point"? And am I defending this kind of abuse?

          In which case, you can come and try to "fucking strangle" me, psychopath.

          Right. We're going to restore the species we've driven to extinction. And then we're going to flap our ar
  • But, certainly military subs have been figuring out their location for quite some time.

    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?

    I'm actually surprised subs don't have an analogue to GPS. Then again, admittedly, I don't know much about subs or most things nautical. :-P

    Cheers
    • by tbo (35008) on Monday March 12, 2007 @04:04PM (#18321571) Journal
      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.
      • Despite all the navigation systems available to the modern world, even to the United States Navy, we still have gaps in our knowledge of the ocean. Recently a US sub crashed into an undersea mountain [nytimes.com]! Cold War-era data on the seafloor has been declassified [noaa.gov], but still our navigation isn't all that great.

        By the way, here [tamu.edu] is a free oceanography textbook!
    • Most navigation in subs is done based on dead reckoning, using highly-detailed charts of the sea floor. At least, that's how they do it in the movies :-) And it's always the reckless captain that endangers the sub by insisting on going faster than the navigator recommends, or trying to get a little too close to that underwater mountain...

      Subs that are near the surface can send up tethered bouys to contact satellites for communication and location purposes, of course. I don't know if there are any position-i
    • by BenJeremy (181303)
      I'm absolutely positive they do.

      This system, however, as a supplimental to the existing systems used in navigation, would provide greater accuracy and a means to recalibrate existing systems.

      I can see this being used in the future to allow submarines the ability to navigate more accurately, even away from a GPS buoy, through shallow areas, thanks to the correction from any drift they may have encountered since their last surfacing.

      Inertial guidance, dead reckoning, undersea terrain tracking and of course, t
    • But, certainly military subs have been figuring out their location for quite some time.

      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?

      The current mechanism is, best as I know, inertial navigation systems periodically recalibrated by GPS when the submarine is at a depth to use GPS, with dead reckoning, as always, the ultimate fallback.

      Certainly, Tom Clan

    • by hey! (33014) on Monday March 12, 2007 @04:44PM (#18322179) Homepage Journal
      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.
  • by Chairboy (88841) on Monday March 12, 2007 @03:57PM (#18321467) Homepage
    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.
    • by Radon360 (951529)

      I don't think that it would be out of reason to see a commercial/scientific version of something like this to eventually come along. It could improve the quality and reduce the cost of underwater surveying or other bathymetry. Such users would be less concerned about having a stealth technology that the Military would so strongly desire.

    • by OverlordQ (264228)
      No offense, but the military wouldn't touch this with a ten foot pole. The whole point of a submarine is to be silent. Active sonar is anything but silent. You might say "Well then the base station will use active sonar then!" And then I'll say those base stations will probably have a lot of accidents since some people dont want their subs to be found.
    • by hcdejong (561314) <hobbes AT xmsnet DOT nl> on Monday March 12, 2007 @04:31PM (#18322015)
      I don't think the military would use this on a large scale, and certainly not in a war zone.

      1. it's an active system. The military avoid the use of active sonar on subs as much as possible.

      2. it's impractical. These beacons would have a range of maybe 100 km, so you'd need to seed lots of them if you wanted to cover a large area.

      3. the beacon can be compromised by the enemy.

      The only military use I see is to aid navigation on the approaches of the sub's home port, so it can stay underwater as long as possible. Even then, those approaches are mapped accurately enough that they can navigate using inertial navigation.

      Due to #2, I expect this system will be popular in situations where you operate in a limited area, but need accurate positioning within that area. Scientific exploration and sea mining/drilling operations come to mind. Submarine cable operations as well, perhaps (for accurate positioning in relation to the ship).
  • by Wiseazz (267052) on Monday March 12, 2007 @03:58PM (#18321487)
    ...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 (Score:4, Insightful)

    by hey (83763) on Monday March 12, 2007 @03:59PM (#18321505) Journal
    Seems to me that this is the kind of unique idea that deserves a patent.
    Unlike most software patents.
    • by Greyfox (87712) on Monday March 12, 2007 @04:35PM (#18322067) Homepage Journal
      Yes but unfortunately it will cause a flood (No pun intended) of "Underwater" software patents now. You're going to have underwater one-click shopping, Underwater shopping carts. Underwater mp3 compression... and the USPTO will grant Every... Single... One.
    • by belmolis (702863)

      I'm curious why you think that. I had just the opposite reaction. It seems too obvious to be patentable. It is analagous to location systems in use on land and in the air, the only difference being that you use a signal that passes through water with little distortion, namely sonar, instead of one that doesn't, such as RF. Why is this a unique, non-obvious, innovation?

    • by suv4x4 (956391)
      Seems to me that this is the kind of unique idea that deserves a patent.
      Unlike most software patents.


      Are you "skilled in the art" of submarine signaling and GPS? Maybe those silly software patents look just as unique to submarine experts.
    • Did you read [0050] of the patent [uspto.gov]? Here's their basic, "original" algorithm:

      % ltpdirect.m
      % local tangent plane position from range and azimuth
      % good for distances less than 10 kilometers
      %
      function newpos=aproxdirect(pos,range,azimuth);
      global DATUM
      delta_east=sin(azimuth)*range;
      delta_north=cos(azimuth)*range;
      n=nphi(pos.lat);
      m=mphi(pos.lat);
      % convert here changes in meters of easting and northing
      % to changes in longitude and latitude
      newpos.lon=pos.lon+delta_east(n*cos(pos.lat));
      newpos.lat=pos.lat+delta_north/m
    • Pshaw! This is a *classic* example of a submarine patent!
  • Have Subs not been navigating for um...years?

    How many base stations, what kind of range before a sub has to send out a pulse that would fry Moby Dick?

    And wont this say to every other sub; "Hey MOFO, I'm over here, about to light up your ship, baby!"?

    Who needs it?

  • Everyone who doesn't believe that the US Navy solved this problem a few decades ago raise their hands! Like in '78 when they launched the satellites, or '79 when the Trident missile entered service....

  • by rodney dill (631059) on Monday March 12, 2007 @04:09PM (#18321677) Journal
    Men will do anything to avoid stopping and asking for directions
  • "GPS doesn't work underwater, as the signal cannot reach the satellite from a submersible"

    GPS satellites transmit the time, the GPS receiver receives these transmissions are uses the differences to calculate the location of the receiver.

    Just thought I would mention that :)
  • Given that sound waves curve in areas of different density (just like light), the receiver must accurately know the acoustic conditions and path between itself and the source else the location is suspect, no?
    • by HardCase (14757)
      Given that sound waves curve in areas of different density (just like light), the receiver must accurately know the acoustic conditions and path between itself and the source else the location is suspect, no?

      Only beyond a certain distance. Unless these are really high powered sonar devices, they'll be transmitting via direct path. It takes a ton of power or really odd sea conditions to use convergence zone or bottom bounce modes. And if they are on opposite sides of the sonic layer depth, it probably won
  • Nothing New Here (Score:5, Interesting)

    by kitecamguy (547592) on Monday March 12, 2007 @04:19PM (#18321825)

    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!

    • It sounds very patentable. It's just that you seem to have quite a bit of prior art in your background.
      • by Dan Ost (415913)
        If there's quite a bit of prior art, wouldn't that make it unpatentable?

        Or am I missing something about the purpose of prior art in the patent process?
        • It sounds patentable. They are just a few decades late to the game. But at least this is not a totally obvious "invention" like the doubly-linked list.
    • by Repton (60818)

      According to TFA, the base station is only at a "known GPS position". It presumably doesn't need an antenna; they just have to know where it is when they install it, and bolt it to the floor so that it doesn't move.

      So it seems to me that you could delete the word "GPS" from this article and everything would still make perfect sense...

      (since you say it's been done before, it's easy to see a parallel with software patents too. Software patent: "We're going to do this thing that everyone does ... on the int

  • Where's the "GPS"? (Score:2, Insightful)

    by snarkbot (1074793)
    "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"
    • by flatulus (260854)
      If you read the patent, it does not require GPS - it can use it if available, but it is a "geoposition" technology. GPS is another geoposition technology. They do the same job, in similar ways.

      Just another case of somebody calling something "GPS" with no clue what it is they are actually saying.

  • I'm surprised there isn't prior art on large parts of this - we've been using sonar for decades for mapping, target acquisition and whole lot of areas related to range and direction finding.
  • by kfstark (50638) on Monday March 12, 2007 @04:23PM (#18321897) Homepage
    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
  • The real question is: Will this ever actually be deployed? The market for submarines is small, at best, and there's a lot of ocean floor to cover before this would be generally useful. Also, in wartime, it's rather easier to take out a tethered buoy, even a submerged one, than the GPS satellite system. I'd rate the as a 2 out of 3 of never happening beyond a Proof of Concept stage.
    • by guruevi (827432)
      There are people believing that we will be living under water in one or more big 'Atlantis'-type quarters within 20-200 years. Quite interesting to hear the possibilities and ideas.
  • by kansas1051 (720008) on Monday March 12, 2007 @04:27PM (#18321943)
    Filing a patent application does not mean that you have "patented" something. The link in the summary takes you to a patent application publication. Patent applications typically publish 18 months after they are filed (or in this case, 18 months after the earliest application to which priority is claimed). With USPTO backlogs, it will probably be 5-7 years before anyone at the USPTO even looks at this application and "patents" this invention.
  • ...I guess "underwater" is the new "on the internet" when it comes to patents.
  • Well, if you're willing to give away your position just to find your position, then this is fine. I'd like to see them solve this problem for a sub that's running silent. Since almost all subs are military, and stealthiness is important, that's the real problem. If they don't care about giving away their position, they might as well raise their tethered antenna package above the water-line. That would be a lot less expensi... oh... wait... it's the military. Yes. Let's order this system right now. Be

  • by @madeus (24818) <slashdot_24818@mac.com> on Monday March 12, 2007 @04:30PM (#18322005)
    This seems pretty cool, as it doesn't require anything floating on the surface to be able to work.

    However (and without disregarding the significance of this system), GPS systems designed for use underwater that work in a similar way have been in use by divers and submarines for years, the exception being they rely on a buoy floating above to get it's position from GPS (and then, I believe, calculate the depth/angle from the buoy - which itself is able to get it's own position using GPS for a fairly accurate reading that is trustworthy).

    It seems possible even a small buoy floated - even a small one designed to be very difficult to detect - could in theory give away a that a sub was in the area, if it was spotted during the presumably brief period during which it was being floated to take a reading. However, I'm inclined to think the likelyhood of that being a real problem is fairly small and it's not worth giving up the convenience of being able to do that - not forgetting the same approach also allows you to fit a receiver to it that is able to perform other functions like receiving a high bandwith data transmission.

    The alternative approach that would be required by the system described in this parent would seem to involve the navy having to go around planting somewhat less transient transmitters on the ocean wherever they are operating in the world - which seems like even more of a giveaway. It also seems they will in any case need to take a reading from the surface before they plant the underwater base station, so while once established in a warzone it could be quite useful for the period the submarine was engaged in operations, you'd need to go and plant it the area in the first place, and presumably it would be fairly easy for the enemy to find and disable - or even just move it and really cause trouble...

    Though I don't know what the range is, perhaps it could remain well out of harms way - from a brief reading it seems to outline one method that works over a not-so-useful 10 km, but mentions another that apparently gives accurate readings over thousands of km.

    So while it's a neat idea, current technology (float a buoy with a small GPS receiver in it every now and then, maybe do a data transmission at the same time - and have the ability to that from anywhere in the world without having a base station already set up in the area) doesn't seem in need of a pressing replacement.

    I should add while I know commercial industry does this (and it's used by divers), but I don't know if military submarines actually use this approach, though I can't see any unsurmountable justification that would prevent them from doing so.
  • I mean, I can see the benefits. You can find out where your wandering spouse is spending the night. AND people think you are happy to see them, especially if you extend the antenna.
  • "...as the signal cannot reach the satellite from a submersible"

    Since when do you need to get a signal TO the satellites? (The GPS ground control segment excluded, of course.) Obvious errors and poorly-written summaries aside, though, the real question would be how it performs with real-world acoustic propagation. How does it deal with reflections and refractions from obstacles, thermoclines, the surface, and the ocean floor?
  • by ChrisA90278 (905188) on Monday March 12, 2007 @04:45PM (#18322185)
    This system sounds like it is completely independent of GPS. The tethered bouys would have no need for GPS they would have their position set into them when they were placed on their tether and as this would never change it would not need to receive a GPS signal. So where is the tie in to GPS? OK the ship that is dropping the bouys might have a GPS aboard but it could use some other navigation system.

    As for military subs not wanting to give their possition away. Yes of course they would not use this. I suspect the best use of this would be for non-millitary scientific or salvage subs.

    One way to make a sonar based system that would be require the sub to emit signals is to have each bouy send it's location and the exact time. Subs could passively listen to this an deduce their position. This is exactly how GPS currently works with pasive radio recievers

    Another way for a sub to directly use GPS that might even work for the military would be to place a GPS antenna in a small float and release the float tethered to a long wire.
  • as the speed of sound through water is not a constant, but is affected by water temperature.
    Furthermore you can't presume the water temperature is constantly the same as the temperature of that measured outside the sub, as the temperature of the sea is not constant and the sea has transient thermal layers, which themselves reflect sound at the boundaries.
    • by HardCase (14757)
      Temperature has some effect, but above the thermal layer depth, the speed of sound is fairly constant - around 4800fps - because the decreasing temperature is offset by the increasing pressure. Below the layer, pressure affects the sound and tends to cause the sound "rays" to bend up to areas of lower pressure.

      The boundary reflections are kind of interesting - if you have a sharp enough sonic layer depth, sound that gets through the layer can be trapped in a "channel" formed by the sonic layer depth on the
  • Take a platform who's only real reason for existing is stealth, and give it a navigation system that reveals its presence and location.

    If (manned) submarines don't care about their location that can just surface to antenna depth and use the (*&^^## GPS.
  • GPS = Global Positioning System, just because the current system is something else doesn't make "underwater" not GPS. Currently many GPS recievers supplment their satalite singal with something simular to this idea: WAAS (which is just another satellite, but kinda the same idea).

    Anyway, I can't wait for "Tom, Tom, bring me to Atlantis."

  • Submarines? (Score:5, Funny)

    by Sax Maniac (88550) on Monday March 12, 2007 @05:06PM (#18322517) Homepage Journal
    100 comments and nobody's asked whether this is a submarine patent [wikipedia.org] yet? Come on, guys! You must be working or something.
  • FTS:

    "GPS doesn't work underwater, as the signal cannot reach the satellite from a submersible..."


    The signal goes the other way...FROM satellite TO surface.
  • This is sonar navigation, using GPS to calibrate the locations of the sonar transponders.

    -jcr

  • This sounds like a basic surveying technique: nail down one or more reference locations, then to locate any spot on the site shoot the reference points from it. If all you've got is a station that can tell you azimuth and inclination, you need to shoot two reference points and basic trigonometry gives you your exact location. Add in range and you only need one reference point (but two are usually used for error-checking). I was taught this way back in community college, including the use of GPS stations as

"I got everybody to pay up front...then I blew up their planet." "Now why didn't I think of that?" -- Post Bros. Comics

Working...