Satellite Failure Behind GPS Timing Anomaly (itnews.com.au) 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.
It were the russians (Score:2, Funny)
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.
Re:It were the russians (Score:5, Informative)
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.
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Frankly, I would consider a system that worked like that a big improvement.
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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
should of hacked Galaxy 15 4080 H (Score:2)
and made it free.
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SVN? (Score:1, Offtopic)
Use for surface navigation (Score:5, Interesting)
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Especially if it happens to be a 4km error in altitude....Die Hard 2?
Re:Use for surface navigation (Score:5, Informative)
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) [wikipedia.org] 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
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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.
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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.
(TFA != Headline) == 1 (Score:3, Informative)
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?
Re:(TFA != Headline) == 1 (Score:4, Funny)
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.
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But then you would have no excuse to complain, and where is the fun in that?
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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
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"Unusable" is a standard field in the DECOM template, see https://celestrak.com/GPS/NANU... [celestrak.com]
And doing a little browsing, I see that SVN32 had an earlier notice: http://www.navcen.uscg.gov/?Do... [uscg.gov]
The earlier notice was of type FCSTUUFN -- Forecast Unusuable Until Further Notice: Scheduled outage of indefinite duration. And that notice says that the start time of that unusability period was 025/1500. And the start time of the unusability period in the DECOM notice you linked was 36 minutes after that: 025/1536.
Re:(TFA != Headline) == 1 (Score:4, Funny)
First Post ! (Score:5, Funny)
First Post !
I'm able to post that fast 'cause i'm using a GPS-synced clock.
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This story is rather a followup than a dupe.
Lack of replacements? (Score:2)
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..
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[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.
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"GPS upgrade set to launch on replacement mission" (February 20, 2014)
http://www.usatoday.com/story/... [usatoday.com]
""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: [space.com]
celnav skills (Score:2)
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That just shivers me timbers.
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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?
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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.
Drones fly away? (Score:2)
I wonder how many DJI Phantoms (the Phantom Menace) and other drones decided to fly 4Km away at that time?
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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.
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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.
GPS WTF?! (Score:1)
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.
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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.
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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 RAIM work around this issue? (Score:2)
Wouldn't GPS RAIM be able to work around this issue anyway (leaving only consumer GPS devices with problems?)
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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.
SVN? Really? (Score:1)