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Government Hardware

Satellite Failure Behind GPS Timing Anomaly ( 62

Bismillah writes: The recent 13-microsecond timing anomaly was caused by a satellite failure triggering a "software issue", the USAF 50th Space Wing has confirmed. Such an error is large enough to cause navigation errors of up to 4 km. Luckily, no issues with GPS guided munition were reported. Reader donaggie03 adds a link to the official explanation from Rick Hamilton, Executive Secretariat of the Civil Global Positioning System Service Interface Committee. From Hamilton's email: Further investigation revealed an issue in the Global Positioning System ground software which only affected the time on legacy L-band signals. This change occurred when the oldest vehicle, SVN 23, was removed from the constellation. While the core navigation systems were working normally, the coordinated universal time timing signal was off by 13 microseconds which exceeded the design specifications. The issue was resolved at 6:10 a.m. MST, however global users may have experienced GPS timing issues for several hours.
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Satellite Failure Behind GPS Timing Anomaly

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  • by Anonymous Coward

    They hacked the satellite and caused the damage. When they declare war, they will turn off GPS world-wide, and all the US nuclear rockets will be misguided and will land on American soil. We must vote trump so that putin is scared of our army.

    • by bobbied ( 2522392 ) on Thursday January 28, 2016 @06:24PM (#51392071)

      You are funny, in a deranged sort of way...

      You do realize that the current crop of missile based nuclear weapons are pretty much independent of the GPS system, having been developed BEFORE GPS was built by about a decade.

      GPS launches started back in 1978 and it was a couple of years before we had enough satellites in orbit to be useful. So GPS came on line sometime after 1980.

      The LGM-30 Block 3 is our current land based ICBM and it went into service a decade before in about 1970, but really is a refinement of a 1962 missile. It is guided by an inertial navigation system and is totally independent of outside input while in flight, so it doesn't need to use GPS.

      The current Navy missile is the Trident 3 (USM-96) which uses a guidance system that is both inertial and refines its guidance using astronomical observations in flight. It was developed in the late 70s, but does NOT use GPS during flight for guidance. It too predates a working GPS constellation by at least a decade.

      If the Russians are messing with GPS in hopes of disrupting our nuclear capability, they are a lot more stupid than I ever imagined... The reality is that GPS is not used for positioning information for any kind of nuclear weapon delivery system and it's not used as an exclusive positioning source for any critical military application. This is mainly because the system is already known to be vulnerable to upset and jamming, so alternatives have been considered, alternate equipment obtained, personnel trained in how NOT to depend on GPS.

      • It's been a while since I read my 80s techno thrillers, but the idea was a nuke sub (or mobile land-based launchers, in theory, but I don't think they ever bothered with that) would use GPS to get an exact fix on where it was, and input that into the missiles as their start point for inertial navigation. This allowed for 'first-strike' capability, which required silly amounts of precision to hit hardened launch sites on short notice, before enemy C&C could authorize retaliatory strikes, and simultaneou

    • by jeneag ( 441998 )
      They can ask Russians to use their GLONASS system. They already depend on them for rides to ISS.
  • SVN? (Score:1, Offtopic)

    Go Git.
  • by techno-vampire ( 666512 ) on Thursday January 28, 2016 @05:59PM (#51391891) Homepage
    Back in '72, when I was in the Navy, one of my friends was a Quartermaster's Mate, involved in (among other things) navigation. He told me that when we went from Pearl Harbor to Subic Bay, in the Phillipenes, that they used 2000 yards for a Nautical Mile, [] rather than the more accurate 2025, and treated all turns as "point turns" instead of working out the distance needed to make the turn. When we made our landfall and were able to pinpoint our location, we were within two nautical miles of our location by dead reckoning. [] This will give you an idea of how little an issue this probably was for ships or aircraft, although it might have been a problem for guided munitions with no human oversight.
    • by TheOzz ( 888649 ) *
      An aircraft in inclement weather using GPS to find an airport might also have a problem with a 4km error.
      • by sims 2 ( 994794 )

        Especially if it happens to be a 4km error in altitude....Die Hard 2?

      • by tlhIngan ( 30335 ) <slashdot@wor[ ]et ['f.n' in gap]> on Thursday January 28, 2016 @06:46PM (#51392209)

        An aircraft in inclement weather using GPS to find an airport might also have a problem with a 4km error.

        Nope, because if you were using a GPS approach, you'd have checked your destination for sufficient GPS satellite coverage. RAIM (Receiver autonomous integrity monitoring) [] is something a safety-critical GPS receiver provides. If there are less than 24 satellites in the constellation, it MUST be consulted.

        Basically when you have more satellites than needed to acquire a GPS fix, the additional satellites give you two things - one, an oversolution (Finding GPS location is solving a system of equations - if you have three satellites, you can do an X, Y and Time and get a 2D fix. To get a 3D fix, you need four satellites. If you have more satellites, they can be used to hone your position further.

        The second use is to detect bad satellites - by comparing the results with one satellite out of the calculations at the time, you can detect the bad satellite because your calculations with the satellite in will be vastly different than if it is out. This is what RAIM does, and for GPS approaches, you must have sufficient satellite coverage for RAIM to operate and work. At a minimum, it's +1 more satellite

        • by TheOzz ( 888649 ) *
          If all satellites are off by 13 milliseconds then you end up with all good signals but a bad position. Not the case here, but just saying.
    • by crbowman ( 7970 )

      I don't want to be off by two miles on any ship that has to navigate subsurface obstacles before it can produce a fix using visible land features.

      • The ship managed to navigate all the way across the Pacific Ocean, in deep water with a cumulative position error of only two miles, well over a decade before GPS was available. And, we were still in deep water, well away from any subsurface obstacles when we made landfall and were able to get an exact fix. (On a clear day at sea, the horizon is about 25 nautical miles away. I don't know how far out we were when we were able to identify and use landmarks, but I'd be surprised if we were closer than 20 mi
    • by AmiMoJo ( 196126 )

      Where GPS can save your bacon is when you get disoriented or make a mistake, and lose track of your position or speed. Dead reckoning is great until something unexpected happens. It's worse for aircraft due to sensors being a bit less robust, and the fact that they can't just stop and ask for assistance.

  • by Anonymous Coward on Thursday January 28, 2016 @06:01PM (#51391909)

    In classic Slashdot style, the headline says a hardware failure and TFA says a software bug temporarily mitigated by an operational procedures change.

    Just dreaming, but it might be nice if the poster read TFA so the rest of us don't have to?

    • by ColdWetDog ( 752185 ) on Thursday January 28, 2016 @06:20PM (#51392033) Homepage

      In classic Slashdot style, the headline says a hardware failure and TFA says a software bug temporarily mitigated by an operational procedures change.

      Just dreaming, but it might be nice if the poster read TFA so the rest of us don't have to?

      This is really a test. You just passed it.

      Not sure where it gets you, but this is Slashdot, after all.

    • ..or you could read the summary where it says "This change occurred when the oldest vehicle, SVN 23, was removed from the constellation." and generously assume that SVN 23 was removed because of a hardware failure and the removal of a satellite from the constellation triggered the software defect and thus both interpretations are correct.

      But then you would have no excuse to complain, and where is the fun in that?
      • by Whip ( 4737 )

        You *could* assume that SVN23 was removed because of a hardware failure. But since SVN23 was scheduled to be decommissioned right about now (or, at least, before the launch of a new satellite next month), I'm not sure that's the assumption *I* would make.

        Really, if it was a satellite failure, I'd expect the official statement to say "there was a satellite failure" rather than "the configs got screwed up when we decommissioned something". There's nothing anywhere that says there was any kind of failure (oth

    • by LynnwoodRooster ( 966895 ) on Thursday January 28, 2016 @07:48PM (#51392605) Journal
      Not unexpected. /. is overwhelmingly populated by software types. The first thing they ALWAYS blame is the hardware...
  • by psergiu ( 67614 ) on Thursday January 28, 2016 @06:01PM (#51391911)

    First Post !
    I'm able to post that fast 'cause i'm using a GPS-synced clock.

  • The ability to fund and replace the network of legacy satellites well past their design life seems to be the issue.
    Even to bolster the backup capability thats ready in orbit.
    The life capability is been stretched out for many more years and the conservative number of backups is now starting to show for the fleet.
    The "reserve role" is even been packed with older systems rather than replacement with new..
    • by Zak3056 ( 69287 )

      [citation needed]

      Per wikipedia, 11 new satellites have been launched in the last five years, 18 in the last ten. This argues against your "we just afford to can't replace them" claim.

      • by AHuxley ( 892839 )
        Re 'we just afford to can't replace them"
        "GPS upgrade set to launch on replacement mission" (February 20, 2014) []
        ""We have a lot of satellites that are well past their design life,""
        " "We're trying to prevent any sort of outage and (have) some backup capability on orbit.""
        ""We've really gotten remarkable performance out of them, but they are aging, and there are some components that simply wear out," s"
        "US Air Force Launches New GPS Satellite" (February 21, 2014)
        http: []
  • Time to service your sextant and brush up on your celestial navigation skills.
    • That just shivers me timbers.

    • I depend on dead reckoning wherever I go navigating... Hand me that compass and a stop watch! That's all we needed when I was young and bare foot in the snow, going uphill, both ways.

      Sextants are for sissies and unless you know what time it is, generally useless during the day.

      Why is there moss on the other side of that tree?

      • Why is there moss on the other side of that tree?

        Because you're in the Pacific Northwest and EVERYTHING is coated on all sides by moss.

  • I wonder how many DJI Phantoms (the Phantom Menace) and other drones decided to fly 4Km away at that time?

    • by Anonymous Coward

      0, as navigation wasn't affected at all.
      Protip: If your navigation depends on a GMT-GPS time offset field, you're doing it wrong.

    • by sims 2 ( 994794 )

      Would that be covered by warranty? Afaik the standard failure mode RTC (aka return to china where the drone takes off at top speed in the direction of china) is not covered.

  • by Anonymous Coward

    We have systems with GPS-disciplined oscillators in them, and certain older models of GPS receivers went berserk during this event. This caused a lot of WTF?! activity until we concluded there was nothing wrong with our software. It really was GPS that was acting up.

    • by Anonymous Coward

      I work in cellular and most base stations use GPS to sync, but due to past issues where something similar to this happened, our stuff is designed to use a majority vote for timing, so if one or two satellites have this happen, it doesn't effect us. You should consider modifying your hardware to do the same.

      • by Whip ( 4737 )

        This was not a problem where "one or two satellites" had something bad happen. Even well-designed GPSDOs had a problem with this one, since large chunks of the constellation were broadcasting a bad A0 parameter.

        The best-designed, of course, went "uh, something really weird just happened with time, I'm gonna stop tracking GPS and throw an alarm," but that had nothing to do with getting disagreeing data from satellites and everything to do with good clocks realizing that a 13s jump in time meant something som

  • Wouldn't GPS RAIM be able to work around this issue anyway (leaving only consumer GPS devices with problems?)

    • by Whip ( 4737 )

      Not in this case, because the particular error was a configuration error that multiple satellites were broadcasting (and they agreed with each other). RAIM works by noticing that a satellite differs a lot from what is expected based on what the rest of the constellation is doing... when a chunk of the constellation is all saying the same (wrong) thing, RAIM can't really do anything about it.

  • "when the oldest vehicle, SVN 23" This might explain everything. You will always loose time, this is why GIT is faster! (sarcasm)

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