[time-nuts] Fwd: CGSIC: FW: Official Press Release - GPS Ground System Anomaly

jimlux jimlux at earthlink.net
Thu Jan 28 12:22:36 UTC 2016

On 1/27/16 11:46 PM, Magnus Danielson wrote:
> Fellow time-nuts,
> Here is the official statement.
> Cheers,
> Magnus

I know we're all time-nuts here and not position-nuts.  The thing in the 
statement that was intriguing was about GPS guided munitions.

13.7 microseconds is about 4.5 km.

I've not been following this discussion too closely, but were the nav 
solutions from the GPS steady and continuous during the event (that is, 
was just a time discontinuity).  I'm guessing that since the problem was 
only in the "how to convert from GPS to UTC" parameters that the nav 
solution was steady.

And this brings up an interesting question. On receivers that provide a 
1pps, do they bring out the 1pps on GPS time or on UTC time.  I suspect 
some are GPS and some are UTC.

And, did this "ripple in the force" cause all those NTP synchronized 
clocks to hiccup (if a NTP ticker is UTC driven vs GPS driven)

> -------- Forwarded Message --------
> Subject: CGSIC: FW: Official Press Release - GPS Ground System Anomaly
> Date: Thu, 28 Jan 2016 01:13:13 +0000
> From: Civil Global Positioning System Service Interface Committee
> (CGSIC) <cgsic at cgls.uscg.mil>
> Reply-To: cgsic at cgls.uscg.mil
> To: cgsic at cgls.uscg.mil <cgsic at cgls.uscg.mil>
> All CGSIC:
> Air Force Official Press Release - GPS Ground System Anomaly
>     On 26 January at 12:49 a.m. MST, the 2nd Space Operations Squadron
> at the
> 50th Space Wing, Schriever Air Force Base, Colo., verified users were
> experiencing GPS timing issues.  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.  U.S. Strategic Command's Commercial
> Integration Cell, operating out of the Joint Space Operations Center,
> effectively served as the portal to determine the scope of commercial user
> impacts.  Additionally, the Joint Space Operations Center at Vandenberg AFB
> has not received any reports of issues with GPS-aided munitions, and has
> determined that the timing error is not attributable to any type of outside
> interference such as jamming or spoofing.  Operator procedures were
> modified
> to preclude a repeat of this issue until the ground system software is
> corrected, and the 50th Space Wing will conduct an Operational Review Board
> to review procedures and impacts on users. Commercial and Civil users who
> experienced impacts can contact the U.S. Coast Guard Navigation Center at
> (703) 313-5900.
> V/R
> Rick Hamilton
> CGSIC Executive Secretariat
> GPS Information Analysis Team Lead
> U.S. Coast Guard Navigation Center
> 703-313-5930
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