[time-nuts] Fwd: CGSIC: Known Problem With Certain GPS Devices
SAIDJACK at aol.com
SAIDJACK at aol.com
Thu May 15 18:39:55 EDT 2014
It would be good to understand which receivers are adversely affected by
this.. the USCG did not list affected vendors/devices..
In a message dated 5/15/2014 15:19:51 Pacific Daylight Time,
magnus at rubidium.dyndns.org writes:
Hi fellow time-nuts,
I think this message is interesting. It shows that some receiver vendors
have been cheating on an important detail, ignoring the health status
and being confused as a result.
-------- Original Message --------
Subject: CGSIC: Known Problem With Certain GPS Devices
Date: Thu, 15 May 2014 21:20:23 +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>
May 15, 2014
Recently, many GPS users have reported intermittent GPS outages in their
devices. After investigating, the U.S. government has linked the
problem to flawed processing of GPS satellite data within certain GPS
receiver chipsets. The GPS satellite service continues to function as
designed and is fully operational and available worldwide.
The problem affects only user equipment that erroneously ignores the
satellite health status information broadcast from every GPS satellite.
The problem is not related to the April 28, 2014, activation of civil
navigation messages on the GPS L2C and L5 signals.
Since March 15, 2014, the Air Force has been conducting functional
checkout on a GPS satellite, designated Space Vehicle Number (SVN) 64.
SVN 64 broadcasts a data message that clearly indicates SVN 64 is
unusable for navigation. Nevertheless, the U.S. government has
confirmed that certain GPS receivers are using data from SVN 64, in
violation of GPS interface specifications, resulting in outages or
corrupted, inaccurate position calculations.
The Air Force testing is scheduled to end in mid-May 2014 at which time
SVN 64 will begin normal operation. At that point, these problems may
stop occurring. Meanwhile, the U.S. government urges all GPS device
makers to review their products for compliance with the GPS interface
specifications, and if necessary, to issue software/firmware updates to
users as soon as possible. View specifications
Users experiencing GPS outages should check with their device
manufacturers for available software/firmware updates. In addition, any
civil user seeing unusual behavior in GPS user equipment should report
it to the U.S. Coast Guard Navigation Center (NAVCEN). Aviation users
should file reports consistent with FAA-approved procedures. Military
users seeing unusual behavior should report it the GPS Operations Center
Please direct any civil user questions to NAVCEN at (703) 313-5900,
Please direct any military user questions to the GPSOC at (719)
567-2541, DSN: 560-2541, gpsoperationscenter at us.af.mil
Military alternate: Joint Space Operations Center, (805) 606-3514, DSN:
276-3514, jspoccombatops at vandenberg.af.mil
Technical explanation for device makers (PDF)
CGSIC Executive Secretariat
GPS Information Analysis Team Lead
USCG Navigation Center
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