Re: Is SA selectively on (or off)?

From: Heinrich Pfeifer (nws_at_gartrip.de)
Date: 01/03/05 

Date: Mon, 3 Jan 2005 09:58:38 +0100

"It's_me" <no_name@end_of_universe.com> wrote in
news:G2SBd.11211$3m6.4061@attbi_s51...

> However, even
> with six satellites locked, the reporetd error was never below 150 ft; I
> tried this several times during the day, getting the similar error
> figures.
> I repeated the experiment in Bangalore and Chennai and got similar
> results -
> errors in the range 135 - 180 ft. This leads me to speculate that the SA
> feature (bug) is selectively turned on/off based on the satellites'
> position
> over the globe. Has anyone else seen this? Any reports in the media on
> this?

India is closer to the equator than your home location, I guess. Last summer
I had a stay in a tropic area, too, and I found that the GPS satellite
coverage was worse than at home. The satellites screen of my Garmin showed
sats with high azimuth very rarely. This is caused by the fact that the sats
fly along a slanted path around the earth.

And actually, sats with low azimuth are shaded easily by any obstacle, and
their signals are more affected by the atmosphere/ionosphere. 

-- 
Heinrich
http://www.gartrip.de
mail: new<at>gartrip.de

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