Scudley - 18-2-2010 at 12:42 PM
Increasing solar activity may affect GPS readings by up to 10m, See article. A 10m change in position in 1 second is 36km/hr.
This brings up the question can GPS max speed reading be considered accurate?
S
Hardrock - 18-2-2010 at 04:48 PM
I'd say it could defiantly affect max speed.
I remember the pre 2000 GPS days when Selective Availability was being used. You could stand in the yard and watch your position move all over the
place. It really sucked. Then Clinton had it switched off. Least he did something right.
Do sun spots affect GPS signals? I was sitting out on the lake years ago and the radio started picking up a Texas station, here in SC. That was so
weird.
arkay - 18-2-2010 at 04:53 PM
And they've been paying more attention to solar weather for arctic flight plans... several flights have been rerouted to prevent passengers from
getting unneeded solar chest xrays 
Neat stuff!
http://www.ametsoc.org/atmospolicy/documents/space%20weather...
ripsessionkites - 18-2-2010 at 05:06 PM
does this really matter??? if you hit 100+ its good already. just feeling the rush and getting out in extreme winds is worth the trip than some GPS
telling what your actual was. technical BS.
guess, its time to buy a speed radar gun.
flyboy15 - 19-2-2010 at 07:30 AM
haha, i think the solar rays may increase the margin of error (MOE) of the GPS by 10m, but i dont think it will affect the top speed calculations.
Its happened to my gps a few times, where the MOE has been over 50m. if yours is waas capable that might help the problem, it usually drops my margin
to within 10 ft of me.
GPS systems realize that they have error margins and will calculate how the sphere of error moves around lol. In other words, they won't keep
guessing where you are in your 100m error margin, they will "watch" this error bubble that is created and see how the whole sphere moves. I've
personally have only seen max speed calculations get messed up while the gps is initializing. As it starts to grab satellites it hones in on your
position. Sometimes it will produce a fix on 3 satellites, and add a 4th or 5th that correct it by 500 yds or something, and then the gps might think
you just shot across the field.
I'm interested to see what happens, that would be funny if you looked at your gps at the end of the day in low winds and see 60 mph lol.
That polar thing is funny tho! If you become an airline pilot you actually are rated by the government as a radioactive worker lol with the same
amount of exposure as those working in a nuke power plant 
indigo_wolf - 19-2-2010 at 09:41 AM
I never really thought about it.
I can see Rip's point.
Once my older eTrex (but still post SA) registered a max speed of 550+mph. :o
I just patted my Honda Prelude and whispered "Good job, girl." 
... I was very happy that I had opted for the spoiler... Woogly.
ATB,
Sam
macboy - 19-2-2010 at 11:44 AM
My Prelude would only do 340.......damn....you must have got a Friday car!