Quote:
Originally Posted by DifferentPointofView
Isn't the difference of whether your on the street or beside it is because (if it's true) the tectonic plates move about an inch every year? and satellites have to be calibrated every so often?
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The satellites are calibrated more than often
Quite frequently. If they weren't, their internal clocks (which need to be sync'd) would get quite off rather quickly (the whole faster your travel the slower time moves thinger
)
But even with moving plates and such - that doesn't change your position (we don't update the latitude/longitude maps based on continental position). And that said, you don't need to know exactly where you are to know how fast you're going - you just need a relative current and previous position (and time). Think of "Back to the Future" - "We don't need Roads"
GPS hardware designed for road navigation will probably fudge map displayed position a little if you're close to a road to show that you're on it. I've noticed that in more rural areas - but that doesn't mean the GPS is off (could - heaven forbid - be the map itself is slightly off
)