[time-nuts] Better GPS

[jimlux]

Brooke Clarke wrote:
> Hi Bob:
> 
> Here's an interesting sidebar:
> Precision Modeling for Orbit Determination 
> <http://www.aero.org/publications/crosslink/summer2002/02_sidebar2.html>
> from the web page:
> Orbit Determination and Satellite Navigation
> http://www.aero.org/publications/crosslink/summer2002/04.html
> I didn't know the Moon tides can change the elevation of LA by 40 cm!
> 


oh yeah... all my GPS/geodetic friends at work say that once you get 
down into the "sub-meter" range for gps (or sub 3 ns..same thing) 
there's a whole raft of errors in that ballpark.. tidal displacement, 
ionosphere, multipath, atmospheric refraction, etc.

They say it's sort of a "whack-a-mole" when you're trying to get better 
than that (for non-differential measurements)