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Transportation Security

Cyber Threats Prompt Return of Radio For Ship Navigation (reuters.com) 133

Jonathan Saul reports via Reuters: The risk of cyber attacks targeting ships' satellite navigation is pushing nations to delve back through history and develop back-up systems with roots in World War Two radio technology. Ships use GPS (Global Positioning System) and other similar devices that rely on sending and receiving satellite signals, which many experts say are vulnerable to jamming by hackers. About 90 percent of world trade is transported by sea and the stakes are high in increasingly crowded shipping lanes. Unlike aircraft, ships lack a back-up navigation system and if their GPS ceases to function, they risk running aground or colliding with other vessels. South Korea is developing an alternative system using an earth-based navigation technology known as eLoran, while the United States is planning to follow suit. Britain and Russia have also explored adopting versions of the technology, which works on radio signals.

Cyber specialists say the problem with GPS and other Global Navigation Satellite Systems (GNSS) is their weak signals, which are transmitted from 12,500 miles above the Earth and can be disrupted with cheap jamming devices that are widely available. Developers of eLoran - the descendant of the loran (long-range navigation) system created during World War II - say it is difficult to jam as the average signal is an estimated 1.3 million times stronger than a GPS signal. To do so would require a powerful transmitter, large antenna and lots of power, which would be easy to detect, they add.

Cyber Threats Prompt Return of Radio For Ship Navigation

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  • Tried, tested, already developed. Why is a new version needed?

    • Re:LORAN-C (Score:5, Informative)

      by Chris Mattern ( 191822 ) on Wednesday August 09, 2017 @07:16AM (#54972899)

      LORAN-C depends on transmission stations, a lot of which are gone (although some aren't). The US and Canadian stations were shut down in 2010. Since they have to build new stations anyways, why not incorporate improvements? There's been a lot of advances since the 1970s.

      • Re:LORAN-C (Score:4, Interesting)

        by queazocotal ( 915608 ) on Wednesday August 09, 2017 @07:36AM (#54972955)
        The possibility of advances is limited. The wavelength the signal is transmitted on (to gain the above benefits of being long range and hard to jam) has various problems with the fundamental transmission that mean high data-rate or 'modern' services have real problems.
        In principle, you might add a really low bandwidth data channel that would over the course of a few hours inform a receiver where the new transmitters are, but they will normally be created at such a rate that stored in firmware, rarely updated is fine.
        There is little to 'improve' very much.
        • Re:LORAN-C (Score:5, Informative)

          by Anonymous Coward on Wednesday August 09, 2017 @09:30AM (#54973593)

          This article discusses the improvements that eLoran offers: http://gpsworld.com/innovation-enhanced-loran/ The article lists the following key differences between Loran-C and eLoran:
                  All transmissions are synchronized to UTC (like GPS)
                  Time-of-transmission control
                  The ability to use differential corrections (similar to DGPS)
                  Receivers use “all-in-view” signals
                  Includes one or more Loran data channels that provide: Low-rate data messaging, added integrity, differential corrections (dLoran and/or DGPS) and other communications including navigation messages.

          • Many of those aren't actually improvements that are meaningful (if you're not using 'all-in-view' when designing a new reciever you're not trying).

            However, these are all irrelevant in that all of the transmitters and antennas are now shut down, and presumably a large fraction of them have been hauled away as scrap.
            • I was actually developing a LORAN receiver for high-altitude balloons at the time it got scrapped, rather annoying.
    • As I understand it, all transmitters, globally have been shut down.
      https://en.wikipedia.org/wiki/Loran-C#Loran-C_in_the_21st_century

      Hence the need for new ones.

      "The European Union had decided that the potential security advantages of Loran are worthy not only of keeping the system operational, but upgrading it and adding new stations. This is part of the wider Eurofix system which combines GPS, Galileo and nine Loran stations into a single integrated system.

      However, in 2014, Norway and France both announced
    • Re:LORAN-C (Score:5, Informative)

      by Maury Markowitz ( 452832 ) on Wednesday August 09, 2017 @07:35AM (#54972949) Homepage

      > Why is a new version needed?

      The accuracy is not high enough to avoid collisions in busy areas. eLORAN adds:

      1) QOS signals so you know if a station is bad
      2) dLORAN (a-la dGPS) which greatly improves accuracy
      3) globally synced signals (a-la Omega) so you can use any signal as the basis for measurements against any other
      4) easy identification of ground vs. skywaves

    • The original network should never have been dismantled. As a pleasure boater, LORAN-C was the cat's meow. I had my mooring position stored, my low-cost receiver never failed to alarm within 50 feet of the spot.
      • by Strider- ( 39683 )

        And your GPS is faster, smaller, more accurate, and cheaper. With the modern multi-constellation receivers (GPS + Galileo + GLONASS) there's no reason to go back to LORAN. I sail, often in bad weather, limited visibility, and in isolated areas. GPS is the cat's meow.

        • by bn-7bc ( 909819 )
          And wit a dual fregencu Galileo reciver you will get down to 1m (3.3 ft) accuracy once all ther sattelites are up and operational in 2020. I`m not certain about how jammable they are, but if that is a concern get yhe comercial service which will provide integrety warnings, so at least you know when solutions can`t be trusted
  • by ls671 ( 1122017 ) on Wednesday August 09, 2017 @06:08AM (#54972687) Homepage

    This sounds right, I have got to get myself an ham radio again some day...

  • by dwywit ( 1109409 ) on Wednesday August 09, 2017 @06:09AM (#54972693)

    I'm surprised, but not really surprised, that modern commercial shipping doesn't have reliable backup systems - that's what the article seems to imply. I mean, how does a commercial sea-going ship's captain get certified without knowing some basic navigation skills - dead-reckoning, anyone?

    Fair enough, dead-reckoning probably wouldn't suffice to avoid collisions in a major shipping channel, but still, you should be able to avoid the dry bits without having to rely on GPS. You can always turn on lots of flashing lights if you've lost communications - someone will come to help.

    • by gwjgwj ( 727408 )

      I'm surprised, but not really surprised, that modern commercial shipping doesn't have reliable backup systems - that's what the article seems to imply. I mean, how does a commercial sea-going ship's captain get certified without knowing some basic navigation skills - dead-reckoning, anyone?

      /quote> Sextant, precise clock - those should be enough if you get lost. And radar to avoid collisions.

      • by Anonymous Coward

        I doubt the problem is getting lost.
        More like they want to avoid running aground.

        • More like they want to avoid running aground.

          For this, you have pilots. Every harbour I've worked in has required, for vessels above a certain size, that they marshal at a location outside the harbour, with sufficiently deep water (deeper than the harbour), and await a pilot boarding from a small boat. The pilot then guides the vessel's master into the harbour, being aware of where the sand banks are this week. If the boat has the most incredibly detailed high tech GPS system, they do exactly the same thing

    • by Anonymous Coward

      The problem with this is when navigating a shipping lane where you need to be in the right spot and there are underwater obstacles. With shipping lots of obstacles cannot be seen (as they are beneath the sea) also many reefs take out ships which are out of position, this even happens with GPS so without it there will be trouble.
      A Sextant is crap as it needs to be night (to see the stars) and you need to work hard. Working a sextant in day time is very inaccurate due to the size of the sun and it's rapid pac

      • Re: (Score:3, Insightful)

        by Anonymous Coward

        They now have this new invention called "navigation charts".

        You can compare a "chart" to your radar and see where you are relative to any underwater obstacles.
        And if you are in the middle of the ocean, you just need to keep away from other contacts and follow your gyro.

        This is all last-century stuff I suppose, but WWII-quality navigation was pretty damn good even without the GPS.
        And there are plenty of people still around that remember using it.

      • A Sextant is crap as it needs to be night (to see the stars) and you need to work hard. Working a sextant in day time is very inaccurate due to the size of the sun and it's rapid pace.

        You have no clue what you're talking about. The sun moves across the sky at exactly the same pace as the other stars. Any sextant you didn't procure from a $2 junk store comes with solar filters for use with the sun during daylight hours.

    • They actually have high navigation skills, without them they would not get the degree.
      Close to the coast everything is full with buoys, lighthouses and other marks anyway.
      GPS is more for the lazy, and of course 'course plotters'. It is important to know that GPS can easy be up to 40 meters off, which is e.g. important in the northern baltic sea. Usually your GPS receiver can be 'programmed' to correct for such offsets.

    • commercial shipping wants a robo captain

    • Depending on how the system handles the failure, you may not need to know to use the backup systems.
      If the GPS is saying lost signal. Yep use the backup system.
      If the GPS is 1 degree off, you may not realize the problem until it is too late.

      Even with non-naval jobs.
      At work we keep a live nightly backup of the data, and archive the rest. More often then not when there is a problem, the nightly backup isn't good enough and need to dig in the archive then find a way to merge the data back. Because it was suc

      • by Strider- ( 39683 )

        If the GPS is 1 degree off, you may not realize the problem until it is too late.

        This would actually very difficult, if not impossible to achieve. GPS works by trilateration. The receiver computes its precise local time (atomic levels of accuracy), and uses that to calculate the distance to each of the satellites being used in the solution. Then, based on the precise time and its precise knowledge of the satellite orbits (which the satellites also transmit), it can figure out where it is.

        In order for an adversary to shift the geographic position, they would have to completely replace th

    • by RNLockwood ( 224353 ) on Wednesday August 09, 2017 @08:57AM (#54973321) Homepage

      All ships use the AIS collision avoidance system. The sending ship sends a radio signal that contains information about the ship, its position (derived from GPS), and its course and speed. The receiving ship has a receiver that displays the information from nearby vessels (and its own position and course) overlaid on a chart. Without the position derived from GPS the system collapses.

      Dead reckoning can give a good approximation of where the ship is, if the navigation monuments (lighthouses, etc.) can be picked out from the buildings on the shore, especially at night with thousands of of other lights on the shoreline.

      The problem isn't so much running aground as avoiding collision. Picking out running lights of a ship against the background of the shore lights can be daunting. Even then it's a guess as to the ship's course and there may be several ships that need to be watched perhaps with only the mate on watch to keep track of everything.

      Read about the recent collision of the USS Fitzgerald and the MV ACX Crystal.

      • by Strider- ( 39683 ) on Wednesday August 09, 2017 @12:35PM (#54975661)

        All ships use the AIS collision avoidance system. The sending ship sends a radio signal that contains information about the ship, its position (derived from GPS), and its course and speed. The receiving ship has a receiver that displays the information from nearby vessels (and its own position and course) overlaid on a chart. Without the position derived from GPS the system collapses.

        Actually, without GPS, AIS will collapse, but not due to the loss of position signal. AIS is based on Self-organizing TDMA to manage on-air resources. Each second is divided up into 2250 time slots, which are precisely aligned with UTC seconds. The accuracy is such that for Class A beacons, this can only be derived from timing signals from the beacon's internal GPS receiver.

        That said, AIS is only one tool in the arsenal. Ships also have dual radars, and if that goes bad, there's always the MK1 eyeball and MK0 ear.

        I was out sailing this past weekend, and the visibility was utter shite. We passed within 2 miles of the Crystal Serenity, the largest cruise ship doing the Alaska run, and the only reason why we knew she was there was due to our radar, the fact that we heard her fog signals, her crew's chatter on the radio, and lastly because we had her on AIS. It's all about redundancy and alternate means.

        • Right, I agree. I heard that the US Naval Academy stopped teaching celestial navigation for a few years but recently decided that it was a good idea in case the GPS systems went down.

          As far as AIS goes if the GPS system is out or jammed there's no way to show your ship's position nor any other ship's position so that makes it useless and it's foolish not to use it in conjunction with radar.

          My not so long nautical career started on merchant ships with no radar, just eyes and ears. The last time I was OOD i

        • Thank you! But that doesn't make for a good salacious clickbait headline, does it?

          They also failed to mention that LORAN is only good around coastlines. I have fond memories of sailing in the Santa Barbara channel using LORAN, where if you got a fix every 30 minutes or so you felt really good about life in general.

          I guess "modern" mariners are just pansies LOL
    • by rtb61 ( 674572 )

      Starlight, starbright. Want to go even further back, watch the skies, well at least get a computer to watch the skies https://www.livescience.com/34... [livescience.com], so pick the brightest for a location fix and of course there is our own sun and moon. So tweak to adjust the light sensor to suit a specific frequency of starlight and know the time/date and you are pretty much done, tie that into radar and then well, if you are fussy, provide satellite upload for shipping telemetry and everything should be fine. In fact s

    • What about using a sextant and paper maps?
    • The backup system is bridge officers paying attention, pass to the right (port) and honk twice if you are going to pass on the left.

      It helps that the Ocean is very very big.

  • Nope (Score:5, Informative)

    by Maury Markowitz ( 452832 ) on Wednesday August 09, 2017 @06:54AM (#54972821) Homepage

    > the descendant of the loran (long-range navigation) system created during World War II

    Nope. That was LORAN, later known as Loran-A. eLORAN is a slightly upgraded Loran-C, which was entirely post-war. They are similar in name only and worked on entirely different techniques and frequencies.

  • This old but effective technology [wikipedia.org] has been discontinued for sea navigation around 1990 to be replaced by Loran-C and GPS. Although not so accurate, it was very reliable, and cheap to mantain and use. LF beacons still survive for aerial navigation, although the transmitter number has been significantly reduced recently. It wouldn't be that bad to have them ready to be switched on when needed.

    • Re:Naval NDB (Score:4, Interesting)

      by Maury Markowitz ( 452832 ) on Wednesday August 09, 2017 @07:10AM (#54972875) Homepage

      > This old but effective technology

      As a pilot that used NDB, it would agree with the "old" but not "effective". Flying an approach against NDBs in the bumps while dodging snow squalls was an experience that made even my cast-iron stomach start to turn. Modern electronics could fix this by doing the work for you, but at an expense level far beyond GPS.

      The idea of using any locallized transmitter is a non-starter for budget reasons, and one in the VHF moreso due to the required antenna sizes. NDB is dead, and good riddance.

  • by fraxinus-tree ( 717851 ) on Wednesday August 09, 2017 @06:58AM (#54972833)
    > Unlike aircraft, ships lack a back-up navigation system

    Really? Ships had pretty reliable means of open sea navigation for at good 1000++y before GPS and even before the first aircraft, gradually improved trough the centuries. Paper maps, magnetic compass, more or less accurate clocks, tools for optical measurements? Whatever happened to them?

    LORAN is good, but it is just as vulnerable as GPS and is pretty much the same basic technology, having infrastructure on the ground instead of space.

    OTOH, sun/star/compass-based navigation can be improved by modern technology and still work autonomously on the ship. The fog and the clouds, preventing optical measurements by naked eye are almost non-issue in infrared. And more, now we have modern laser gyroscopes and precise accelerometers for a good inertial add-ons.
    • Yep, all convention ships have onboard magnetic compasses. Chart plotters still have charts without GPS, large ships still have radars and echo-sounders without GPS, and large ships in confined locations will have local pilots aboard, and possibly escort tugs attached. Ships themselves are marked with lights and signals. If GPS drops out, locationing will be more difficult sure. It will not be a pan-global epidemic of ship collisions and allisions.
      • If GPS drops out, locationing will be more difficult sure. It will not be a pan-global epidemic of ship collisions and allisions.

        It will be a pan global epidemic of ships getting lost.

    • Really? Ships had pretty reliable means of open sea navigation for at good 1000++y before GPS and even before the first aircraft, gradually improved trough the centuries. Paper maps, magnetic compass, more or less accurate clocks, tools for optical measurements? Whatever happened to them?

      A: You need a sextant or some such; such things are not generally carried on ships any more. B: You need someone highly trained to navigate this way; it is no longer guaranteed that you'll have a navigator trained for it.

      • by angel'o'sphere ( 80593 ) on Wednesday August 09, 2017 @08:22AM (#54973131) Journal

        Every ocean going big vessel has several sextants.

        C: The sea is enormously more crowded than it was in centuries past. The relatively low accuracy of these methods is no longer good enough.
        What has crowdedness to do with GPS? Ships see each other by radar, AIS, and lights. And they use radio to negotiate if that is necessary.
        GPS only tells me where I am, and nothing else (of course it calculates heading and speed from repeated positions), in particular it does not tell me anything about other traffic.

        • by arth1 ( 260657 )

          Ships see each other by radar, AIS, and lights. And they use radio to negotiate if that is necessary.

          Even lanterns and flags in cases where a vessel can't radio. Even sound in case of fog.

        • GPS only tells me where I am, and nothing else (of course it calculates heading and speed from repeated positions), in particular it does not tell me anything about other traffic.

          Right, - then there is this https://www.marinetraffic.com/... [marinetraffic.com]

          This whole GPS versus Loran business is for some facacta reason, is presented in range war fashion, yet what Loran does is give us land based location that is one way. It's a fine adjunct to GPS and last resort sextant use.

          But the concept that so many have fallen into (not you, as this is a general observation) is that if we lose GPS, that Loran will be one of "the old ways are the best ways, and get off my lawn while you are at it" memes.

          • There are also coastal radio stations.
            If you have an rough idea where you are (which you always should have), you call a few of them and ask if they pick you up. From the answers you can estimate how far you are to each of them and hence get a good estimate (+/- 5 nm) for your position. If they were fancy, which they probably are in disaster situations, they even can get a bearing on you and you can pinpoint your position quite accurately.

            Anyway, my sailing career is pretty fresh :D only about 1000nm so far

            • by PPH ( 736903 )

              they even can get a bearing on you

              Or you can get a bearing on them. Huff-duff [wikipedia.org].

              • If we are only talking about small boats, then they don't have the equipment to get a bearing on a radio station on land. You could try a loop antenna, but in the scenario I described before the actual antenna would be in the mast (for range) and you would need to climb up there and hold a loop antenna to get a bearing (I simplified)

                • by PPH ( 736903 )

                  Rotating loop antennas is 1930's technology. A dipole array driving a scope X and Y chanels is still old, but gives instantaneous direction readings. DSP techniques simplify this process quite a bit.

                  The advantage of doing your own direction finding is that you don't have to bother shore stations, who might be busy. Or even let them know you exist, which might have tactical advantages.

                  • True. But I was more considering civil uses if a recreational boat is 'lost' and not tactical situations :)
                    And in such cases people have usually no material at hand to make a home build bearing device.

                    I guess I need a book about that .... after I made my SRC license.

        • What has crowdedness to do with GPS? Ships see each other by radar, AIS, and lights. And they use radio to negotiate if that is necessary.

          AIS is a self organizing network that explicitly uses GPS as a clock source. If you take out GPS AIS is gone too.

          • Only part of AIS is gone (actually not really).
            The ship will still maintain its heading and speed information and react on radar pings from other ships.
            Time information from GPS is not super important, ships have clocks, too. And the more important satellites are those related to the AIS system: https://en.wikipedia.org/wiki/... [wikipedia.org]
            However: in case the GPS satellites are jammed, AIS is probably, too .... and even more important: in such cases you likely want to switch off AIS anyway (yes that is strictly speaki

            • by Strider- ( 39683 )

              Class A AIS (that used by SOLAS/Commercial vessels) is utterly dependent on GPS to function. Without it, the on-air interface will not work. AIS uses two VHF channels, and each channel is divided up into 2250 time slots per second. These time slots are aligned to UTC time, and without a GPS time base to keep all the transceivers on all the ships worldwide, the system simply doesn't work. In fact, all the standards related to AIS, and the type approval requirements for the transceivers expressly forbids them

      • Sextant is good and even a relatively small ships carry more than one. Highly trained, my ass. A day of training for a clever man, that is. Or a month for a barely reading, but motivated one.

        And I don't imply that the sextant has to be mechanical and human-operated. A simple webcam w/ an infrared filter and not so complex software can do. There is an app for that (probably!).
    • Actually, expensive military ships sometimes have automated sextants which work during the day, I keep forgetting what they're called. So there's GPS, and then the celestial navigation system, and then compasses and sextants before they have to give up and use the radio

    • by tlhIngan ( 30335 )

      Really? Ships had pretty reliable means of open sea navigation for at good 1000++y before GPS and even before the first aircraft, gradually improved trough the centuries. Paper maps, magnetic compass, more or less accurate clocks, tools for optical measurements? Whatever happened to them?

      Well, technically determining longitude reliably (and easily) was actually quite hard, and only became a solved problem in the past 300 years or so. The development of the marine chronometer was one of the major events tha

      • by Strider- ( 39683 )

        Well, technically determining longitude reliably (and easily) was actually quite hard, and only became a solved problem in the past 300 years or so. The development of the marine chronometer was one of the major events that helped make it easy to determine your longitude.

        The humble chronometer was pretty much the atomic weapon of its time. The ability to reliably place themselves on the planet is what allowed the Royal Navy to rule the seas for a century or more.

        On an unrelated note, if you're ever in London I strongly recommend a visit to the Admiralty Museum, and the Greenwich Observatory. They have Harrison's Chronometers on display, and they're still functional centuries later.

    • by jwdb ( 526327 )

      LORAN is good, but it is just as vulnerable as GPS and is pretty much the same basic technology, having infrastructure on the ground instead of space.

      False. GPS can be jammed for miles with no more power than in a cell phone battery, and with an antenna that comfortably fits in a pocket. Doing so with LORAN takes KW of power and an antenna you need a mast to support.

      It's physically more difficult to jam LF.

  • by Matt_Bennett ( 79107 ) on Wednesday August 09, 2017 @07:03AM (#54972847) Homepage Journal

    No matter what radio based technology you have, RF can be jammed- just pump enough energy into the air- and the closer you are to the target, the easier it is. The downside to jamming of that method is that it is really obvious. A better method is to produce an accurate, but wrong signal. If you want to create a trustworthy RF navigation system the signal must be authenticated. Most forget that the GPS system in our cell-phones is only the first step of the actual military system- it gives you a good estimate so you can switch to the more precise encrypted signal (rotating keys that are classified and have a pseudo-noise sequence that never repeats in the valid lifetime of the key, which is on the order of months).

    Without a method to prevent spoofing via a verifiable chain of trust, the system dead before it begins.

    • Minor correction: "A better method is to produce an accurate, but wrong signal." should be "A better method is to produce an apparently accurate, but wrong signal."

    • by Maury Markowitz ( 452832 ) on Wednesday August 09, 2017 @07:29AM (#54972935) Homepage

      > just pump enough energy into the air- and the closer you are to the target, the easier it is

      But that's just it... in the case of GPS everyone is very far from the broadcasters and it is very easy for the jammer to be closer to its target than the transmitter, and very easy to generate more power than the weak signals from the satellite.

      In the case of eLoran this arrangement is highly unlikely. For one thing, your target is likely to be closer to at least one of the transmitters than you are, and the power levels are so much higher that your jammer has to be equally massive.

      It is MUCH more difficult to jam Loran, even in theory.

      • by Strider- ( 39683 )

        On the other hand, GPS signals are spread spectrum, with significant FEC and error correction in them. From what I understand, most GPS jammers work by overwhelming the radio front-end, rather than by masking the original signal. If you were to replace the omni-directional antenna that is normally used for GPS with a directional one and aim it at the sky, that would go a long way to reduce the effectiveness of a jammer.

        • by Agripa ( 139780 )

          On the other hand, GPS signals are spread spectrum, with significant FEC and error correction in them. From what I understand, most GPS jammers work by overwhelming the radio front-end, rather than by masking the original signal. If you were to replace the omni-directional antenna that is normally used for GPS with a directional one and aim it at the sky, that would go a long way to reduce the effectiveness of a jammer.

          It is more like the radio back end. Commercial GPS receivers use 1 bit direct conversion which works fine but provides poor resistance to jamming. The GPS signal starts out below the noise floor and is still weak after despreading. There is no need to overload the RF amplifier or mixer.

          Antennas which have less gain toward the horizon help if that is where the jamming source is but also mask satellites. In a city this does not help because reflections from the jammer will be overhead.

          Implementing various

      • "It is MUCH more difficult to jam Loran, even in theory."

        Not if you're close to the target you want to jam. Free-space path loss is proportional to the square of the distance between the transmitter and receiver, and also proportional to the square of the frequency of the radio signal.
    • But if the jamming source needs to be in the vicinity, you can locate it and blow it out of the water.
    • Most forget that the GPS system in our cell-phones is only the first step of the actual military system- it gives you a good estimate so you can switch to the more precise encrypted signal (rotating keys that are classified and have a pseudo-noise sequence that never repeats in the valid lifetime of the key, which is on the order of months).

      Without a method to prevent spoofing via a verifiable chain of trust, the system dead before it begins.

      Even with encrypted signals all GPS receivers are doing is measuring propagation delay. An adversary at the very least can introduce delay to successfully change calculated position without access to decryption keys.

      These days it is possible for mortals to leverage competing GPS systems operating on different frequencies to get a more detailed picture of ionospheric delay and as a result achieve accuracy approaching encrypted P code.

      • Even with encrypted signals all GPS receivers are doing is measuring propagation delay.

        I have no idea what you think you said here. "Propagation delay" is the delay in a radio signal caused by atmospheric and ionospheric effects and is an error in GPS that is accounted for by external means.

        GPS measures the time it takes for a radio signal to travel from the satellites to the receiver, which includes distance and propagation effects. Using just this information you can get a reasonable location.

        To deal with propagation effects, you need external data from a fixed station. Since the station

        • I have no idea what you think you said here. "Propagation delay" is the delay in a radio signal caused by atmospheric and ionospheric effects and is an error in GPS that is accounted for by external means.

          This isn't rocket science. It means how long it takes for a signal to get from point A to point B. If you change how long it takes by re-radiating signals or changing index of refraction of propagation medium in an unexpected manner you can fool a receiver into thinking it's somewhere else.

          To deal with propagation effects, you need external data from a fixed station.

          For the MOST precise measurements, not only the time delay of the arriving signal is measured, but the carrier phase. Using phase measurements and computing power, the actual number of cycles of the carrier between the satellite and the receiver can be calculated.

          Most uncertainty is locked up in ionospheric conditions which affect how long signal takes to reach receiver. If you have multiple signals on multiple frequencies they can be used as references to reason about ionosphe

          • This isn't rocket science.

            That's right, it is radio science. The delays in signals based on propagation effects are not what GPS measures. It measures the time difference from transmission to reception based on the speed of light. That's part distance, part propagation.

            Most uncertainty is locked up in ionospheric conditions which affect how long signal takes to reach receiver. If you have multiple signals on multiple frequencies

            RTK does not make use of that potential information. Ionospheric propagation effects depend on frequency but are not fixed.

            • Most uncertainty is locked up in ionospheric conditions which affect how long signal takes to reach receiver. If you have multiple signals on multiple frequencies

              RTK does not make use of that potential information. Ionospheric propagation effects depend on frequency but are not fixed.

              Since the same p(y) code is transmitted on L1 and L2 from each satellite, can't that be used to model ionospheric effects?

              • Since the same p(y) code is transmitted on L1 and L2 from each satellite, can't that be used to model ionospheric effects?

                Perhaps. But since the errors due to the ionosphere and troposphere can be measured, along with errors in satellite location and clock signals, that is how DGPS and RTK GPS are done.

  • by Anonymous Coward

    You've been fooled into thinking satellites exist, by a science fiction author.

  • No backup system? You mean the sun and the stars have gone away?
    It worked for me when I crossed the Atlantic.

    Not terribly accurate though, Loran or its modern update would be nice.

    • by muons ( 2774561 )
      The article did not say, but I assume that the issue is primarily collision avoidance. This position data could be sent to AIS so that other ships know their position, speed, heading, DSC information, name for hailing purposes, etc.

      If you crossed the Atlantic using celestial I am going to guess it was on a sailboat going well under 10 knots on a good day and you probably stayed out of major shipping lanes. A ship would see you soon enough to avoid collision (and vice versa though you would be the stan
      • by Strider- ( 39683 )

        The article did not say, but I assume that the issue is primarily collision avoidance. This position data could be sent to AIS so that other ships know their position, speed, heading, DSC information, name for hailing purposes, etc.

        AIS is dependent on GPS for timing and on-air data collision avoidance, in addition to actually encoding the ship's position. Without GPS, an AIS transponder is prohibited from transmitting. The transmission scheme has each second divided into 2250 time slots, and is strictly alligned to UTC time. Without the timing signal from the internal GPS receiver, a class-A AIS transceiver can not ensure that it will only occupy its own time slot(s).

  • This discussion is a little bit stupid / misdirected. The point is not that Loran is inherently more secure or unjammable than GPS. If someone wanted to jam it in the vicinity of a receiver it could be done.

    The point is that GPS is jammed because it helps localize within centimeters, which unlocks a lot of capabilities that an enemy is interested in disabling.

    If Loran did that too, they would go after *that*. Loran doesn't matter to most anyone today aside from ships, because its level of accurac
  • No wonder the US Navy is going back to teaching celestial navigation. If you have a reasonably up to date chart, an accurate time piece, in place nav aids (buoys, markers, etc), a sextant, and the intellect to understand celestial navigation; one can do quite well. I do appreciate that handling a large commercial ship is a bit more difficult than my 31' sailboat, but the principles are the same. Besides, once you get out from the open waters and into a channel, most commercial ships take aboard a pil
  • Unlike aircraft, ships lack a back-up navigation system and if their GPS ceases to function, they risk running aground or colliding with other vessels.

    Anyone who sails out of sight of shore without a backup navigation system (even a sextant) is a weapons grade idiot.

  • Time to dust off the old Sextant?

  • does not happen by GPS, by normal vision or radar.

    Avoiding collisions by GPS would be reckless and violate international law. (Since it would require all vessels to have a transponder, incluing small ones or ones without motor/steering).

    Navigating in shipping routes close to coasts/harbors happens by Buoys.

    So yes, ships have an alternative system.

    About the hypothesis that GPS is easier to jam, i would have to think a little bit.

  • by Registered Coward v2 ( 447531 ) on Wednesday August 09, 2017 @10:14AM (#54974069)

    Until we develop a way to block, or spoof, the sun and the stars there is a reliable and accurate backup for navigation. You need a precise time piece, sextant, nautical almanac, and charts along with a mariner who knows how to shoot the stars. The Nav on a frigate I was on did a daily celestial fix to double check our position with the radio fix. he could get a set of readings very quickly so the line of position produced a very tiny box for our fix. I'd bet my life on his fix before the radio fix.

    The downside is you need to be trained and practice to keep sharp. I used to be good at it but couldn't get a fix to save my life now. With computers you could input the readings and get it to give you lat/long so there is no need to draw LOP on a paper chart. In a pinch you could send that out as you position.

    Automation has caused mariners to lose skills that served our forebears well. One favorite drill a friend ran was to tell the crew GPS was down - now navigate for the next few hours the old way. Lots of head scratching and moaning when he did that. There's a lot to be said for keeping proven, if time consuming, skills sharp for when all the latest stuff goes south.

    • by Nidi62 ( 1525137 )

      One favorite drill a friend ran was to tell the crew GPS was down - now navigate for the next few hours the old way. Lots of head scratching and moaning when he did that. There's a lot to be said for keeping proven, if time consuming, skills sharp for when all the latest stuff goes south.

      With good charts-which any naval or merchant ship should have-if the GPS goes out couldn't you just take your last known position and use your heading, speed, and time to plot out a decently accurate idea of where you are anyway? It might not be accurate enough closer to shore but in deep water it should be serviceable until GPS is restored.

      • One favorite drill a friend ran was to tell the crew GPS was down - now navigate for the next few hours the old way. Lots of head scratching and moaning when he did that. There's a lot to be said for keeping proven, if time consuming, skills sharp for when all the latest stuff goes south.

        With good charts-which any naval or merchant ship should have-if the GPS goes out couldn't you just take your last known position and use your heading, speed, and time to plot out a decently accurate idea of where you are anyway? It might not be accurate enough closer to shore but in deep water it should be serviceable until GPS is restored.

        Sure, dead reckoning can be used ,in fact that's what we did to plot our projected position, but its accuracy dwindles over time, due to currents, course and speed changes, etc. I would not want to have to use it to ensure we hit a known position at some point in he future.

  • by AndroSyn ( 89960 ) on Wednesday August 09, 2017 @11:59AM (#54975239) Homepage

    Since when does RF jamming have anything to do with hackers or "cyber threats". Clickbait headlines I guess.

    Also jamming GPS would require at least line of sight to the receiver if the jammer is on the surface of the earth. Microwave signals don't go over the horizon. If you are jamming a ship at sea, you are either a nation state or a sophisticated pirate(I mean the real ones).

    As far as LORAN-C goes, in many regards this is EASIER to jam since it is using LF bands, around 200kHz. Jamming at low frequencies can be a lot easier due to groundwave and skywave propagation, allowing the jammer to be much further away. That said, the antennas required to transmit LF frequencies are quite enormous in length.

  • I'm so glad they have a backup for a ship. Now if they could just figure out one for the Web..
  • So it may get down to a Multi Billion dollar ship having to rely on a guy with a Compass and Sextent??

    It may not be as accurate as GPS/Radio Beacons but...

    (cue POTC theme here)

  • Ships have several backup systems. One is map and sextant if you want the end fallback. Another is radio triangulation. Yeah, you can use a loop antenna to get a bearing from a commercial radio station broadcasting from a known position. Get bearings from three, and you have a rather exact position. Loran is an automated version of doing the manual bearings I just described.

    GPS is a very good convenience for navigation. But, if that is the only way you know how to navigate; you need a Sea Daddy to tea

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