back to article GPS spoofing countermeasures: Your smartphone already has them

There's suddenly a lot of panic about GPS satellite navigation spoofing, and BAE Systems among others would like to sell the military some tech to resist it. But in fact, most modern smartphones already have strong countermeasures against this sort of thing. UK-headquartered but largely US-based BAE's latest grab for …

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  1. PsychicMonkey
    Mushroom

    Have

    Apple filed the patent for it yet?

    1. The Man Who Fell To Earth Silver badge
      FAIL

      Re: Have

      Joint Direct Attack Munition (JDAM) is a guidance kits, which have been around for about 20 years already are GPS spoofing-proof. JDAM kits contain an integrated inertial guidance system coupled to a Global Positioning System (GPS) receiver. Inertial guidance systems cannot be jammed, although they do suffer from integration errors. Other military munition "GPS" systems are also inertial + GPS.

  2. jake Silver badge

    I use paper maps (AAA is a *good* thing).

    My cell-phone is an eleven year old Nokia 5185, sans GPS.

    Seems to work quite nicely, at least this side of the Rockies :-)

    1. Anonymous Coward
      Anonymous Coward

      Re: I use paper maps (AAA is a *good* thing).

      I kill my food with hand-knapped flint blades, I live in a log cabin and I wear only natural fibres.

      All this newfangled "technology" and "synthetic fibres" and "agriculture" you modern fools use will avail you not one bit come the end times.

      1. jake Silver badge

        @AC 10:08 (was: Re: I use paper maps (AAA is a *good* thing).)

        Thing is, I *can* and have killed food with hand-knapped obsidian blades. I have a log cabin (built by my Great Grandfather in 1890ish, added onto by me twenty years ago using the same techniques). The wife & I teach a "shearing to socks and shirts" class twice a year.

        In reality, I use a humane killer on my livestock, the log cabin is our "get the fuck out of reality" space, and I purchase most of my clothing at Sears. I do grow nearly all the vegetables we use here at the Ranch, though.

        The difference between you and me is that I not only know how it's done, but I can, and actually do it ... and teach how, for people interested. There is no "ap" that substitutes for getting your fingers dirty.

        1. Anonymous Coward
          Anonymous Coward

          Re: "The difference between you and me..."

          Is that I am humourous and you are presumptuous.

          And often tedious.

    2. Anonymous Coward
      Anonymous Coward

      Re: I use paper maps (AAA is a *good* thing).

      Paper maps work without batteries as well...

      1. Charles 9 Silver badge

        Re: I use paper maps (AAA is a *good* thing).

        Only problem is paper maps have this annoying tendency to grow more inaccurate as time passes. Oh, because roads get built, demolished, resurfaced, restructured. Many a driver has gotten lost because the T-intersection they were supposed to find is now a four-way because the road got extended. Or because the map says take the first on-ramp, not realizing a new onramp was just added in front of that one--going THE OTHER WAY.

    3. Anonymous Coward
      Anonymous Coward

      The Rise of the Neo-Luddites

      My phone is shitter/older/less feature rich than your phone

      1. hplasm
        Devil

        Re: The Rise of the Neo-Luddites

        My map is mostly blank, apart from a 'X' and some text at the bottom about 'here be monsters'.

        Could be Seattle, could be Cupertino; can't tell.

        1. Vic

          Re: The Rise of the Neo-Luddites

          > Could be Seattle, could be Cupertino; can't tell.

          Slough.

          Vic.

          1. Anonymous Coward
            Thumb Up

            Re: The Rise of the Neo-Luddites

            > Slough.

            Nah, Rotherham.

            Always in the news, and not in a good way.

        2. jake Silver badge

          @hplasm (was: Re: The Rise of the Neo-Luddites)

          Get your eyes off the technology & roll down your window to observe reality.

          Seattle is dampish & smoggy. Cupertino is dryish & smoggy.

      2. jake Silver badge

        @AC 10:11 Re: The Rise of the Neo-Luddites

        The desk phone at my elbow is an early 1950s Western Electric rotary-dial telephone. It was the first telephone my Father ever payed the lease on. It still makes and receives telephone calls, even during power failures, which is all I want a telephone to do. Hopefully $TELCO won't kill pulse-dialing on land-lines any time soon ...

        But you seem to have an issue with single-tasking tools, AC. Care to explain why?

        1. Anonymous Coward
          Anonymous Coward

          Re: @Jake

          I'm not sure if you've actually read enough articles on here to realise Jake but The Register is a Tech Publication. That means they write about and attract people interested in technology. It is not an antiquated contraptions and ranching publication. Yet, almost every post you make has to reference one or the other.

          Do you go on to the BMW owners forums and tell them how great your bicycle is and how rubbish their cars are?

          The article in question isn't even about smart phones, except as a reference to the fact they the already perform a function which BAE is trying to lever into the military market. Yet still you jump on here "bragging" about owning an old nokia. Who cares? Its not even relevant to the discussion.

          1. jake Silver badge

            @AC 09:07 (was: Re: @Jake)

            You don't think that producing food & clothing is technology? The mind boggles.

            I'm not bragging about the old Nokia. I'm just pointing out that it does exactly what I expect a telephone to do, which is place and receive telephone calls.

            As a side-note, mr/s techno-buff, I'm "jake", not "Jake". Computers tend to be literal.

            1. Anonymous Coward
              Anonymous Coward

              Re: @Jake

              Food? Clothing? I didn't mention either

              Computers are literal, people are not and despite appearances otherwise, I trust you are a person

              1. jake Silver badge

                @AC 09:50 (was: Re: @Jake)

                So, AC 09:50 ... Which AC are you, exactly? Some AC or another mentioned food & clothing ... which are technology, regardless. You're not that AC? OK ... Maybe create a handle that the rest of us can actually get a grasp of who you are and reply to on a one on one basis?

                Remember, I'm "jake", not "Jake" ... Might be hard to grok, but think about it.

            2. Anonymous Coward
              Anonymous Coward

              @Jake 09:44

              My dining table does exactly what I expect a dining table to do and doesn't convert into a snooker table.

              Whoopie doo!

    4. AceRimmer
      Stop

      Re: I use paper maps (AAA is a *good* thing).

      GPS != Mapping

      Of course, the output from a GPS module can be fed directly into a mapping application giving the user a real time pointer to their current location on the map.

      1. jake Silver badge

        @AceRimmer (was: Re: I use paper maps (AAA is a *good* thing).)

        I have a built-in real-time pointer to my location on the map. It's called a brain.

    5. Gene Cash Silver badge
      Stop

      Re: I use paper maps (AAA is a *good* thing).

      I use paper maps, my TomTom GPS, Google maps on my phone, a printout of the Google directions, and a handwritten summary of the important bits from the directions. I intend to not spend hours being lost.

      So what's your point?

      1. Anonymous Coward
        Anonymous Coward

        Re: I use paper maps

        "I use paper maps, my TomTom GPS, Google maps on my phone, a printout of the Google directions, and a handwritten summary of the important bits from the directions..."

        ...Ands that's just when he goes to the kitchen!

      2. jake Silver badge

        @Gene Cash (was: Re: I use paper maps (AAA is a *good* thing).)

        My point is that you would probably have a boat-load more cash in your jeans if you had ever taken a simple "navigation 101" course.

        The only time I use electronics for navigation is in the air, and on open water. On the road, it's hardly useful, much less necessary. I can't remember the last time I was more than a street or two off course.

  3. Dave Bell

    Not just Google, I have an old Nokia phone which does this sort of secondary location fixing from the radio signals.

    The slightly scary thing is that my Android tablet seemed to know where my Wi-Fi router was. Was it Streetview passing by? Or can they get into from my broadband provider?

    1. Steve Evans

      They could have easily got it from you.

      Have you ever had your wifi and GPS turned on at the same time?

      Did you check the option to say you're willing to share the wifi positional data is acquires with google? (You can change your mind by going into location settings and unchecking the "use wireless networks" and then checking it again. It asks for confirmation each time).

      Then again, even if you didn't, someone else walking past (doesn't have to be a streetview car) could easily have been.

      It's actually a useful feature. It allows the device to locate your initial (vague) position very very quickly. A cold start on GPS can take half a minute or so without it, which is a damn long time when you're sat at the front of a queue of traffic trying to work out where you are.

    2. Anonymous Coward
      Anonymous Coward

      Read the T&Cs

      > my Android tablet seemed to know where my Wi-Fi router was

      Yes, you agreed to that somewhere in the 73-page terms & conditions that appear when you first use location on an Android device.

      1. Anonymous Coward
        Anonymous Coward

        Re: Read the T&Cs

        Um, actually it's a really straightforward and obvious option in the settings. Google are certainly evil for many reasons, but this particular item couldn't be more plain as day. You can choose whether you use it or not.

  4. Remy Redert

    @Dave Bell

    That was a Streetview car passing by, or someone with an Android phone and location services enabled. In fact, it was probably several people doing the latter.

    Google probably have some quite precise maps of wifi hotspots throughout most of Europe and the US.

    1. dotdavid

      Re: @Dave Bell

      "Google probably have some quite precise maps of wifi hotspots throughout most of Europe and the US"

      I wish they'd tell us where they were so we could find free wifi internet easily when abroad.

      1. jonathanb Silver badge

        Re: @Dave Bell

        It doesn't have to be free wifi. It can pick up the location from WPA2 protected hotspots even if you don't know the password.

        1. TRT Silver badge

          Re: @Dave Bell

          It even picks up non-SSID broadcast WiFi, WiFi with ACLs, any encryption standard...

          1. theblackhand

            Re: @Dave Bell

            In the hope of avoiding unnecessary concern, Apple and Google (and probably others) are taking the MAC address and the location details and associating the two. As a WLAN AP will always broadcast it's MAC address, ACL's and setting the "hidden" bit won't stop these details appearing unless you turn off the radio or AP.

            They may well be adding SSID information, but I would hope they filtered this to just agreed providers.

            1. Anonymous Coward
              Anonymous Coward

              @ the blackhand

              It's = IT IS

  5. micheal
    Joke

    Typically 'Mercans

    come in years after it was started and claim it's a new thing.....I can see the SER-FUJ-HP-Atos directors salivating at the prospect of bidding for another ring fenced pork barrel

    1. Graham Dawson Silver badge

      Re: Typically 'Mercans

      BAe Systems. Formerly British Aerospace, still has its headquarters in the UK. American?

      1. Anonymous Coward
        Anonymous Coward

        Re: Typically 'Mercans

        There are more BAe Systems employees in the US than in the UK.

        There is more BAe Systems revenue in the US than in the UK.

        You can check this in any Annual Report for the last few years.

        Plus whenever I visited sites like Warton, the "UK employees" always included significant numbers of US citizens "temporarily" working in the UK.

        All in all, I think that makes them not very British.

  6. HamsterNet
    Happy

    Drones

    Two flaws in the story

    1) Encrypted or not it can be spoofed

    2) The US drones where defiantly using just the GPS for navigation.

    Both proofs come from the Iranians landing a drone using GPS spoofing.

    1. Ru

      Re: Drones

      I wouldn't trust what the Iranians have to say any more than I'd trust what the US says back.

      From what the Iranians have said so far, they could have gained the same information from shooting down a drone or waiting for a drone to fail by some other means and salvaging its equivalent of a black box from the wreckage and cobbling together a basic model of its airframe out of plywood and larger bits of debris.

      1. AndyS

        Re: Drones

        The Iranians displayed a complete, undamaged drone, explained how they brought it down, and revealed other bits of on-board info including mission data, past service history etc to prove their point. And tellingly, the US has not denied that what the Iranians say is plausible/possible.

        The simplest conclusion, therefore, is that they did, indeed, bring it down as they say. Any other explanation is currently not as likely. Remember this is a nation on the brink of independently developing nuclear weapons, with a very high level of technological expertise. It's worth taking what they say very seriously.

        Two conclusions:

        1. Whether or not it's possible to encrypt GPS usage so that it cannot be spoofed, the current US attack drones don't do so.

        2. On-board data stored in the drone's computers is obviously not adequately encrypted.

        Neither of these conclusions are surprising, since the whole point of drones is that they can be developed and deployed quickly and cheaply. But I'd be very surprised if there wasn't a fast scramble in the US to sort out their encryption.

        1. Field Marshal Von Krakenfart
          Black Helicopters

          Re: Drones

          The simplest conclusion, therefore, is that they did, indeed, bring it down as they say. Any other explanation is currently not as likely

          maybe they just bought one....

          US defence biz fined for busting China arms embargo

    2. Anonymous Coward 101

      Re: Drones

      '1) Encrypted or not it can be spoofed

      2) The US drones where defiantly using just the GPS for navigation.'

      These facts were clearly stated in the article.

      1. Anonymous Coward
        Anonymous Coward

        @ AC101

        The drones were defiant?

        The end is nigh, I tell you!

  7. VV
    Thumb Down

    Flawed

    "uses other transmissions, such as TV and cellular sites, to confirm a location fix"

    Except that during a war, those are normally wiped first.

    1. Anonymous Coward
      Anonymous Coward

      Re: Flawed

      Plus even if not, do the US/Europe have well mapped locations of such signals in Iran/North Korea?

  8. ukgnome
    Happy

    Jamming rifle

    http://www.theregister.co.uk/2012/02/22/gps_jammers_rife/

  9. Danny 14

    ok

    how about a backup system, celestial guidance? Inertial tracking? Surely the drones know roughly where they are and have inertial equipment onboard? GPS should be a check not a primary solution! If ICBMs could roughly know where they are then surely a drone could.

  10. JaitcH
    FAIL

    Having been rear-ended by people texting ...

    I bought an accessory for my motorcycle, in HongKong, that set me back the equivalent of 29 pounds whixh jams all cell and GPS frequencies including 3G.

    It's small enough to fit in my under-seat storage and the antennae are fairly inconspicuous.

    In the city the range is approximately just over a 100 metres (tested against cells and a GPS receiver). In the open country/highways things get much better. As our CGST (highway police) use speed traps with GPS attached and speed checking is far shorter distanced with a plastic bodied motorcycle/motorscooter, than a huge blob of steel in the form of a car or truck (lorry). Without GPS readings the courts will not accept speeding tickets. The GPS reading is on the picture along with the time, date, compass direction and speed.

    I suspect BAE's wet dream could be as easily defeated.

    1. Anonymous Coward
      Anonymous Coward

      Re: Having been rear-ended by people texting ...

      "I bought an accessory for my motorcycle, in HongKong, that set me back the equivalent of 29 pounds whixh jams all cell and GPS frequencies including 3G."

      So you're saying that when you have an accident and you - or somebody else - is lying in the road, unconscious and bleeding to death, nobody can call the emergency services? And all so that you can roar through speed cameras above the legal limit, most likely causing the aforementioned accident? Moron. You don't deserve an ambulance.

      1. Daniel Evans

        Re: Having been rear-ended by people texting ...

        Also don't see how this avoids the texting problem anyway - you don't need signal to be reading/writing a text.

    2. Timmay
      Facepalm

      Re: Having been rear-ended by people texting ...

      You sir, are a cretin.

      Please explain how wiping everyone's mobile signals within 100m will stop them from texting or being distracted as they approach the rear of your car/bike? I don't know about your phone, but I can happily text away on my phone without a signal, but it obviously won't send. Also, if I was in the naughty situation of using my phone while driving, suddenly losing signal for no reason is probably going to make me more distracted trying to work out what went wrong.

      What is funny is you're doing one illegal thing (jamming signals), to stop people doing other illegal things (using phones while driving), but with the ultimate aim of helping you do illegal things and not get caught (speeding).

    3. Neil B
      Facepalm

      Re: Having been rear-ended by people texting ...

      Please read the replies to your post and take this thing off your bike.

    4. Peter Galbavy
      FAIL

      Re: Having been rear-ended by people texting ...

      Looking forward to the day you end up broken and sprawled bleeding on the road and no one who has stopped to help you can because all their mobiles are jammed by your stupidity.

      1. Charles 9 Silver badge

        Re: Having been rear-ended by people texting ...

        Um...just move 100m out of range and try again. Is it really that difficult to get out of range of a spot jammer?

  11. A J Stiles

    No patent

    There is no way a patent should have been granted on this. It would fail the "not obvious to an expert in the field" test. In fact, if there was a "not obvious to someone whose only clue about it comes from reading half the Wiki page" test, it would fail that.

  12. regorama
    Happy

    already generating huge excitement

    "The potential applications of this technology are already generating huge excitement in both civilian and military circles,"

    Come on El Reg, go interview these excited people - we want to see 'em!

  13. Anonymous Coward
    Anonymous Coward

    Is it just me..

    .. or there something profoundly dodgy about a joint US/UK taxpayer funded setup trying to charge said tax payers again via a patent war?

    I may have read this wrong, but this stinks in many ways..

  14. skuzzzy

    They can find you via your router's MAC address - don't know how often it's updated though.

    http://www.samy.pl/mapxss/

  15. Manolo
    Linux

    WiFi MAC database flaw

    While Google's location service using the MAC addresses of WiFi routers collected by Streetview vehicles is usually accurate, it has an interesting flaw: moving routers.

    I first noticed this when a photo taken at home with my Android phone on a Caribbean island had a Brussels address in the EXIF information. Later, I noticed when using free WiFi in Dutch trains the location to be off with as much as 200 kilometers. Then I figured it out: Streetview vehicle passes, sees router, puts it in database. Router moves (from Brussels to the Caribbean, or on board a train), location is off.

    1. PyLETS
      Linux

      Re: WiFi MAC database flaw

      MAC addresses are routinely configurable in software, so are very easy to spoof, as anyone who has configured a router in expert mode or used Aircrack-NG is likely to know. So these addresses should be expected to relocate, and should not be expected to be globally unique, which was the original intention of making these up using first half as unique manufacturer code and the second half as unique to manufacturer serial number. When I upgraded my home from a computer acting as a router to using a dedicated router I reconfigured the MAC address on the new router to the same as the old Ethernet card on the WAN side so the ISP didn't change my IP address.

    2. jonathanb Silver badge

      Re: WiFi MAC database flaw

      When I tether my iPod Touch to my Android phone the wifi location on my iPod is pretty accurate, even if I am on a train travelling along at 125mph.

      1. TRT Silver badge

        Re: WiFi MAC database flaw

        It's great when you rock up at Euston and the Map.app whizzes you backwards and forwards between Manchester, Stockport, Carlisle and London as you pick up signals from the different Virgin trains.

  16. Albert Stienstra

    Differential GPS is already known for longer than 17 years

    Differntial GPS, to compensate Selective Availability (SA), was known and in use since 1986. It consisted of a radio beacon with known position. This was broadcast to differential GPS receivers, so that the SA offset could be compensated for a certain range (at least tens of miles) around the beacon. It was used a/o in geodetics, to obtain very precise positions, e.g. to find out if a seawall was moving. It was also looked at in the contaxt of car navigation. I do not believe for a moment that this basic idea was patented by BAE Systems or Ploughshare, so I do not think their patent can be worth much.

    1. Anonymous Coward
      Anonymous Coward

      Re: Differential GPS is already known for longer than 17 years

      "I do not believe for a moment that this basic idea was patented by BAE Systems or Ploughshare"

      No, it wasn't. What is being discussed here is fundamentally different from DGPS.

      1. Albert Stienstra

        Re: Differential GPS is already known for longer than 17 years

        From the article:

        Quote: Using ambient radio signals to confirm a location isn't "a real game changer" as BAE systems would have us believe, then, but it is quite a good idea: which is why Google, Apple and other rather faster-moving technology firms started doing it long ago. Unquote.

        This is identical do DGPS

        1. Anonymous Coward
          Anonymous Coward

          Re: Differential GPS is already known for longer than 17 years

          "This is identical do DGPS" [sic]

          In a nutshell, differential GPS relies on removing the noise from the observations at a target receiver by applying a series of corrections (one for each common observable) obtained from a reference receiver at a known position--knowing that those errors are very similar over a relatively large area--such that it is possible to solve for 'e' in the equation C = O + e (where C: corrected value, O: observed value, e: error). In the original technique, called DGPS, this was done by applying the above formula to the pseudoranges at a reference station and either broadcasting the correction values (Real-time DGPS), or committing them to persistent storage so that they could be applied latter (post-processed DGPS).

          A number of refinements followed over the years, the latest of which are so-called space-state solutions, where the corrections are applied to the satellite ephemerides instead of the pseudoranges, and are thus globally valid. Anecdotally, the pioneers in this area, in the commercial arena, were tractor and agricultural equipment company John Deere with their StarFire system, based on previous research by NASA's JPL.

          One important point to note is that if a GPS signal is unavailable, be it due to jamming, obstructions, or system failure, DGPS is of no help whatsoever (the 'O' in the equation is undetermined).

          Now, I am thoroughly unfamiliar with the idea proposed by BAE. My simple and no doubt incomplete and inaccurate understanding, is that this is an evolutionary improvement over the triangulation methods used for radiolocation which have been in use since before WWI (e.g., such as NDBs used in aviation), and is used to complement rather than enhance the precision of, GPS.

          So, would you care to explain then how is this "identical to DGPS", please?

          1. Albert Stienstra

            Re: Differential GPS is already known for longer than 17 years

            You do not have to tell me how GPS works, I was in charge of the team that designed the CARIN system and, later, the Caresse system in Philips, from 1988 to 1999, Your explanation is nothing but a lot of jargon, probably with the aim to come over impressive. It did not work, unfortunately. At an exam session I would probably fail you.

            How is DGPS very similar to the idea used to correct GPS positions in smartphones and the like? Simple, the DGPS protocol is: A GPS position is acquired. It is verified with information from one (or more) local beacon(s), whose position(s) is (are) exactly known. The (if necessary) corrected position is then established.

            1. Anonymous Coward
              Anonymous Coward

              Re: Differential GPS is already known for longer than 17 years

              "the DGPS protocol is: A GPS position is acquired. It is verified with information from one (or more) local beacon(s), whose position(s) is (are) exactly known. The (if necessary) corrected position is then established."

              On that level of detail a Mini and a double decker bus are identical too. They've both got an engine and four wheels. But how many people can you get in a Mini?

              Details matter. At any sensible level of detail, this BAe concept is not like DGPS. Obviously, DGPS allows you to take a trustworthy GPS position and make it better by using specifically designed and built local DGPS transmitter infrastructure and a co-operating DGPS receiver. This shiny allegedly new thing from BAe alleges that it can use existing ("ambient") signals, not needing any new infrastructure at all, to provide a (not particularly high resolution, not particularly accurate [1]) position fix, independent of GPS.

              [1] Resolution (precision) and accuracy are different. I could say that my wages are £3,141,592 euros per week. That is quite a precise number. It is also completely inaccurate.

  17. Anonymous Coward
    Anonymous Coward

    This kind of article is why El Reg is

    This kind of article is why El Reg is still worth reading occasionally.

    Compare and contrast with the earlier article inspired by coverage of the very same BAe press release:

    http://www.theregister.co.uk/2012/07/02/bae_navsop/

    Thank you Bill.

  18. alann2
    Holmes

    haven't we seen this before?

    Surely the RAF, the US airforce, the Luftwaffe and others used radio wave navigation in WW2? so is BAE just re-inventing the wheel?

  19. maccy
    Big Brother

    Anyone lost GPS near Grantham?

    It happened to me twice when driving to Cambridge on the A1. I figured it was either some GPS jamming from a miltary base or Margaret Thatcher's evil miasma.

  20. Antony Riley

    Crap, I said this in a comment on the original article about BAE's technology and got downvoted for it.

  21. Anonymous Coward
    Anonymous Coward

    A-GPS

    Err... A-GPS was around for a while before Google go into the game.

    Skyhook were launched in 2003. The Moto A835 was one of the first phones to use A-GPS, launched in the UK on the 3 network in 2003.

    Google schmoogle.

  22. Colin Millar
    IT Angle

    Missing the point as usual

    This is BAE and the MOD. It's got nothing to do with GPS or security - simply setting up another cash conduit to the BAE ministerial retirement fund.

    By the way

    "Ploughshare Innovations" - I like that.

    Is funny yes cos they have beaten the swords into ploughshares and they're going to have a f*$%*g war anyway and make loadsadosh. Hahaha - that'll teach that peacemongering Isaiah.

  23. NAVSOP

    NAVSOP details

    This article is missing some important details - see

    http://www.theengineer.co.uk/sectors/electronics/news/bae-navigation-system-identifies-suspicious-signals/1013081.article

    and

    http://tech.slashdot.org/comments.pl?sid=2950387&cid=40517317

    Some key differences are the accuracy possible with NAVSOP versus smartphones, the integrity monitoring performed, the ability of NAVSOP to locate spoofers and jammers during operation, the type of measurements performed (Skyhook/Google/Apple only perform RSSI measurements, NAVSOP exploits timing and carrier phase), the learning capabilities of NAVSOP far exceed those of smartphones, the list goes on.....

    If the author is interested in what can really be achieved with smartphones alone, beyond the default capabilities provided by Skyhook, Apple or Google, he should read an award-winning paper from the NAVSOP team: http://www.plansconference.org/abstract.cfm?meetingID=36&pid=51&t=C&s=1%29

    1. John Smith 19 Gold badge
      Boffin

      Re: NAVSOP details

      Thumbing through my copy of the NRL EW Handbook (NRL 9737. Handy for lots of basic electronics) Let me see if I can unpack this.

      You've built a civilian bands Electronic Support Measures receiver (which is what this process basically is) and hooked it up to a database package and a GPS. There might be motion sensors on the package to detect when the *receiver* movers, rather than the sources.

      If you've got GPS you build the emitter database Using your (known) position and as you move you (as measured by either GPS or the IMU motion sensor) work out attenuation factors to get range to source, transmitter power etc by some kind of incremental filter.

      If you loose GPS you continue to record and build the DB in terms of signal strengths, bearings, phase shifts etc. IE You're not at 85deg 45"12'N, 67deg16"5'W but 2km from that 100Kw FM radio station that is 3deg from North.

      Given ESM receivers are complex and power hungry You've presumably got some Special Sauce ( (c) Lewis Page) that speeds up the process and cuts the power requirements.

      Yes you can track a train under a tunnel by the GSM system used for train drivers (does that work in the London Underground?).

      I just find the whole scenario implausible. A "clean kill" that takes out *only* GPS and leaves everything else standing? That sort of ignores several details.

      Military GPS is *much* harder to spoof given the code patterns and are likely to synch up in friendly territory and stay locked on throughout, making civilian GPS corruption irrelevant. As this is BAe's primary target.

      Systems that use GPS for timing reference *still* need a timing reference. I see no provision for getting one through this system.

      There are *multiple* GPS waveforms and the Galileo, GLONAS and Chinese systems. They would also have to be inoperable or ruled out. We're back to the military are we not?

      I like diversity and admire a clever hack as much as any one but I'd suggest that organizations concerned about GPS outage (those that need a position fix, not a 50ns precision clock) would simply make sure their receivers received some of the other signals as well. If they are not the UK MoD they will look at the cost/benefit case and conclude it's just not worth it.

      And of course it's not likely to work very well down a cave in Reganistan or any other bit of primitive mountainous cave pocked country where British troops have been sent as part of the "special" relationship.

      It's an impressive achievement. But is going to be of any actual *use*?

      1. NAVSOP

        Re: NAVSOP details

        If you read the links in the previous comment you will learn that RSSI is not the primary metric for outdoor NAVSOP, timing and carrier phase are, so you in good company and haven't guessed correctly about how NAVSOP works. Signal strength for distance estimation is rubbish for long ranges to transmitters, look up free space path loss. There is a clean kill of GPS every time you go indoors, but many opportunistic terrestrial signals are still available, so that is happening every single day to everybody. All satellite positioning signals have the same failure modes caused by the extremely weak signals at the earth's surface, so adding more satellites doesn't provide true resilience - no sat signal punches indoors like cellular, dab, dvb, etc. All GNSS are susceptible to ionospheric issues, so a severe scintillation event will remove use of all GNSS, etc. Integrity monitoring of GNSS is an important capability regardless of how expensive your GNSS gear is. Opportunistic signals can provide stable timing, that is a key thing NAVSOP learns about. Some digital signals are locked to atomic standards independent of GPS, some are locked to GPS, some are only running at OCXO stability or worse, and those statements are based on experimental evidence.

        1. John Smith 19 Gold badge
          Happy

          Re: NAVSOP details

          "you will learn that RSSI is not the primary metric for outdoor NAVSOP"

          Nor did I suggest it was. You are conflating 2 different parts of my post, one of which was written to give a flavor of how the system switches between GPS available and unavailable modes.

          "timing and carrier phase are,"

          I think cut down ESM receiver architecture (some of which use interferometric methods) is a pretty good short form description. I would not like to try carrying one around however.

          "There is a clean kill of GPS every time you go indoors, "

          Quite possibly. Which would be unimpressive except that GPS was never designed to work *inside* buildings.

          You have a life threatening application that *depends* on GPS for navigation *inside* buildings that's in wide spread use I'm clueless. What is it? Because if you don't I doubt you're going to capture that market. Those people who are using GPS to *supplement* their interior guidance will either use a fall back mode or set up some private backup radio system.

          Joking aside this sounds like you're shifting the goalposts, or the target market. Fixed locations needing precision timing references? Vehicle guidance? Indoor nav?

          "All GNSS are susceptible to ionospheric issues, so a severe scintillation event will remove use of all GNSS"

          Now that sounds like the glimmer of a *plausible* problem. Specifically a high power solar flare (but again high enough to disrupt the ionosphere but not enough to cook the ground level radio infrastructure).

          "Integrity monitoring of GNSS is an important capability regardless of how expensive your GNSS gear is. "

          I think if it's provided by BAe "expensive" is a given.

          "Some digital signals are locked to atomic standards independent of GPS"

          Like what was MSF Rugby at 60Khz (now IIRC moved to 59Khz to harmonize with *global* frequency standards). It can't do the high frequency thing but I'll bet it can *converge* a local oscillator to the correct time accuracy fairly quickly.. I believe HP coined the term "digital vernier" for some clever circuitry to do just that.

          I don't know the details of the system and I'm not interested enough to register to find them out. I'd probably look for the patents that have no doubt been filed for this. You might call me a professional obtrusionist.

          I'm sure it was lots of fun to work out the details of this and fully worthy of getting a PhD but actually getting people to buy it if (unlike the MoD) they actually see they have a choice is likely to be more of a challenge.

          Like email the world has gradually become addicted to GPS to the extent widespread outage for any serious period of time (hours in some cases) could have serious consequences. Is this the answer? IDK.but beware of BAe bearing gifts.

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