For as long as this blog is, one thing that's missing is a discussion of multipath errors. Multipath errors are when the GPS signal reflects off of buildings or

For as long as this blog is, one thing that's missing is a discussion of multipath errors. Multipath errors are when the GPS signal reflects off of buildings or mountains, giving the illusion that the satellite is further away than it is. This is why it can sometimes be hard to get a precise location in cities.