[time-nuts] Fwd: CGSIC: Known Problem With Certain GPS Devices

Magnus Danielson magnus at rubidium.dyndns.org
Fri May 16 23:01:50 UTC 2014


They can't point official fingers. That's why.

Ask you vendor if they need firmware upgrades to comply in this aspect.

Cheers,
Magnus

On 05/16/2014 12:39 AM, SAIDJACK at aol.com wrote:
> 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.
>
> Cheers,
> Magnus
>
>
> -------- 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>
>
> All CGSIC:
>
> 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
> http://www.gps.gov/technical/icwg/
>
> 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
> (GPSOC).
>
> Please direct any civil user questions to NAVCEN at (703)  313-5900,
> http://www.navcen.uscg.gov
> Please direct any military user  questions to the GPSOC at (719)
> 567-2541, DSN: 560-2541,  gpsoperationscenter at us.af.mil
> https://gps.afspc.af.mil
> Military  alternate: Joint Space Operations Center, (805) 606-3514, DSN:
> 276-3514,  jspoccombatops at vandenberg.af.mil
> ----
> See also:
> Technical explanation  for device makers (PDF)
> http://www.navcen.uscg.gov/pdf/gps/GPSOC_PRN  30_Notice.pdf
>
> V/R
> Rick Hamilton
> CGSIC Executive  Secretariat
> GPS Information Analysis Team Lead
> USCG Navigation  Center
> 703-313-5930
>
>
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>
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>
>
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