[LEAPSECS] GPS certified for navigation?

Robert Seaman seaman at noao.edu
Thu Sep 23 16:00:09 EDT 2010

Ah! Much simpler than http://bit.ly/bwkyGC

...and sextants are even usable while in motion: http://bit.ly/aiWlyf :-)

Isn't the point of many of the issues you describe that you may *not *get what you paid for?

"Ability to notice errors" - now there's a phrase to inspire confidence!

On Sep 23, 2010, at 12:35 PM, Steve Allen wrote:

> 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

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