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

[Tom Van Baak]

> 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.

Jim,

Nav solutions were fine. Time solutions were fine. It was just a UTC offset 
problem (and then only for some receivers).

> 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.

Almost all timing receivers allow you to choose between GPS time and UTC. It's 
in the manual. The TBolt and Z38xx-series and 58503-series make it really easy 
to switch from one to the other.

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

[jimlux]

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 +
From: Civil Global Positioning System Service Interface Committee
(CGSIC) 
Reply-To: cg...@cgls.uscg.mil
To: 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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Re: [time-nuts] Fwd: CGSIC: FW: Official Press Release - GPS Ground System Anomaly

[Magnus Danielson]

Jim,

On 01/28/2016 01:22 PM, jimlux wrote:

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.


That is exactly what Meinbergs research as presented by Martin shows.
In particular, it's the A0 coefficient of the GPS to UTC conversion 
message which is out of tune.



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.


You can configure, most of them would default to UTC and in my 
experience, many systems wants 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)


NTP bumping around 13,7 us... I'm not sure I *really* care for most usage.

Oh... not to speak about telecom and broadcast networks. When national 
TV broadcast networks suffers greatly, we start to care about these 
things. *GREATLY*


Cheers,
Magnus





 Forwarded Message 
Subject: CGSIC: FW: Official Press Release - GPS Ground System Anomaly
Date: Thu, 28 Jan 2016 01:13:13 +
From: Civil Global Positioning System Service Interface Committee
(CGSIC) 
Reply-To: cg...@cgls.uscg.mil
To: 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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Re: [time-nuts] Fwd: CGSIC: FW: Official Press Release - GPS Ground System Anomaly

[Magnus Danielson]

Tom,

On 01/28/2016 04:58 PM, Tom Van Baak wrote:

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.


Jim,

Nav solutions were fine. Time solutions were fine. It was just a UTC offset 
problem (and then only for some receivers).


Quite a lot of receivers it turns out.

The way it works, many receivers could go lucky through the events.


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.


Almost all timing receivers allow you to choose between GPS time and UTC. It's 
in the manual. The TBolt and Z38xx-series and 58503-series make it really easy 
to switch from one to the other.


I find that most use in telecom and broadcast is to set them for UTC.

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

[Magnus Danielson]

Poul-Henning,

On 01/28/2016 11:27 PM, Poul-Henning Kamp wrote:


In message <56aa6aa2.6050...@rubidium.dyndns.org>, Magnus Danielson writes:


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)


NTP bumping around 13,7 us... I'm not sure I *really* care for most usage.


I don't think most NTPD based servers would even notice the pattern I
saw on my receivers.



Indeed. Even if they saw it, as soon as you got past the first router 
that bump is nothing anyways.


I just *might* have been using a bit of an understatement.

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

[Poul-Henning Kamp]

In message <56aa6aa2.6050...@rubidium.dyndns.org>, Magnus Danielson writes:

>> 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)
>
>NTP bumping around 13,7 us... I'm not sure I *really* care for most usage.

I don't think most NTPD based servers would even notice the pattern I
saw on my receivers.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Fwd: CGSIC: FW: Official Press Release - GPS Ground System Anomaly

[Scott McGrath]

What was interesting was in addition to the bump was that the Garmin nav 
receiver in the car was unable to get a fix until it did a full cold start

Content by Scott
Typos by Siri

> On Jan 28, 2016, at 5:37 PM, Magnus Danielson  
> wrote:
> 
> Poul-Henning,
> 
>> On 01/28/2016 11:27 PM, Poul-Henning Kamp wrote:
>> 
>> In message <56aa6aa2.6050...@rubidium.dyndns.org>, Magnus Danielson writes:
>> 
 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)
>>> 
>>> NTP bumping around 13,7 us... I'm not sure I *really* care for most usage.
>> 
>> I don't think most NTPD based servers would even notice the pattern I
>> saw on my receivers.
> 
> Indeed. Even if they saw it, as soon as you got past the first router that 
> bump is nothing anyways.
> 
> I just *might* have been using a bit of an understatement.
> 
> Cheers,
> Magnus
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[time-nuts] Fwd: CGSIC: FW: Official Press Release - GPS Ground System Anomaly

[Magnus Danielson]

Fellow time-nuts,

Here is the official statement.

Cheers,
Magnus

 Forwarded Message 
Subject: CGSIC: FW: Official Press Release - GPS Ground System Anomaly
Date: Thu, 28 Jan 2016 01:13:13 +
From: Civil Global Positioning System Service Interface Committee 
(CGSIC) 

Reply-To: cg...@cgls.uscg.mil
To: 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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