Just a quick note regarding 'old' and 'new' satellites (if it matters any more
). The GPS satellites are in geosynchronous orbit, which means they don't move relative to the surface of the earth.
If you move, however, on the surface of the earth (and by a fair distance, though I don't know what that is off the top of my head), then different satellites may be used...
Just my 2 cents (as someone who just registered tonight
).
Fantastic website, BTW!!
FG