[IGSSTATION-5727] GPS CNAV activation

[Nacho Romero]

Dear IGS members and participating institutions,

Please note that the US Department of Transportation has announced the 
start of a continuous broadcast message on L2C and L5 (CNAV) from the 
most modern GPS satellites (IIR-M & IIF) starting during April, 2014.

This decision is open for comment here: 
https://federalregister.gov/a/2014-04856

If you have comments please access the website and make your voice heard 
by 4 April, 2014.

The IGS, after evaluation, will not comment on this action as we are 
confident that the IGS network is not at risk due to this change, and 
its a welcomed step towards GPS modernization.  The IGS is also working 
to accommodate the CNAV messages in the Rinex 3 navigation files.

This event is considered innocuous to the stability of the receiver 
network since during a limited GPS CNAV test campaign in June 2013 the 
IGS network was not affected, only a very specific receiver problem was 
detected by the IGS Multi-GNSS Experiment, which was informed to the GPS 
ground segment and addressed.  Most modern receivers can track L2C and 
L5 and the CNAV messages, but the decoded messages should not be used by 
the receivers. The traditional L1 NAV messages (LNAV) will continue to 
be transmitted as usual and thus the receiver navigation files, brdc, 
etc, will continue unaffected. Older receivers will be completely 
unaffected as they do not track L2C or L5.

In any case IGS Station Operators and Station Network Managers are 
advised to keep an eye on receivers and on their data outputs during the 
start of the CNAV activation. Just in case something strange is observed 
please stop data submission and notify the IGS (Network Coordinator, 
Infrastructure Committee) so that we may investigate the issues 
quickly.  In case of doubt with your own equipment please contact the 
receiver manufacturer and inform the IGS.

-- 
Best regards,
Nacho Romero
IGS Infrastructure Committee Chair
  _______________________________________________________________

Ignacio (Nacho) Romero
Aerospace Engineer, PhD
SAC @ ESA/ESOC/HSO-GN
http://nng.esoc.esa.de
http://www.canaryadvancedsolutions.com
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Gracias por su colaboracion.
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