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) <cg...@cgls.uscg.mil>
Reply-To: cg...@cgls.uscg.mil
To: cg...@cgls.uscg.mil <cg...@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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