How accurate those figures are considering the accuracy of a GPS receiver ?
Wouldn't be a radar gun way more accurate ?
I think a GPS is just good enough to get a rough estimate of position, altitude and speed. No more.
It could be interesting to test them side by side anyway
I 'm sure it all has to do w/ the sample rate of the particular unit involved as opposed to the GPS as a concept. I've tested 3 seperate units and found them all to be quite accurate.