PSN-L Email List Message

Subject: Re: GPS and solarflairs
From: Brad Douglas rez@..................
Date: Sat, 07 Apr 2007 05:05:06 +0000


On Fri, 2007-04-06 at 00:18 +0000, Jón Frímann wrote:
> Hi all
> 
> I want to point out artical about solar flairs and how they can disrupt
> a gps signal. 
> 
> http://www.reghardware.co.uk/2007/04/05/solar_flares_zap_gps/
> 
> It is worth tracking solar flares since most of us recording earthquakes
> use gps to keep track of time.

Keep in mind that we're just now coming up from a solar minimum and this
next cycle is supposed to be particularly strong (but solar modeling is
far from diagnostic).

Not only can solar flares disrupt propagation paths, but can also alter
the atmospheric index of refraction and gas composition, further
complication matters of spacial precision.

Here's an overview of the effects on positioning due to medium
(atmosphere) alteration by solar interaction:
http://citeseer.ist.psu.edu/418582.html

GPS is resistant to flares to a certain level, but has been demonstrated
in the last cycle (where user density was much smaller and SA was on)
that they can be knocked out for periods of time.

The GLONASS and next gen GPS constellations should address these
concerns.  We have a few years to go before the solar maximum.

Personally, I'm a little more concerned with ISS than satellites.  It's
impossible to do an EVA in those conditions and only limited areas of
the ISS are shielded.


-- 
73, de Brad KB8UYR/6 

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