[LEAPSECS] GPS certified for navigation?

[Steve Allen]

On Thu 2010-09-23T11:59:33 -0700, Robert Seaman hath writ:

> What precisely is the status of GPS for actual purposes of navigation?


You are in a twisty little maze of bureaucratic regulations, all alike.

You get what you pay for in GPS.  There are significant differences in
the abilities of receivers to notice whether they are receiving
signals that are self-consistent.

In the long run, there's intentional problems like theater-level
spoofing (which the US military have used for years, as,
unfortunately, noticed by the Keck telescope control timing systems)
http://www.gpsworld.com/defense/security-surveillance/assessing-spoofing-threat-3171

For ability to notice errors see RAIM
http://en.wikipedia.org/wiki/Receiver_Autonomous_Integrity_Monitoring

For IFR aviation in the US the FAA has technical standard orders
TSO C129 (A1) and TSO C129 (A2)
describing the requirements.

for robustness against the ionosphere (mostly for surveying) see WAAS
http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System

For marine traffic in US harbors the Coast Guard requires AIS
http://en.wikipedia.org/wiki/Automatic_Identification_System

--
Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
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