I've been reading about GPS to find how it works, but one thing still bothers me.
To calculate distance from GPS unit/receiver to GPS satellite, it uses the difference between radio signal sending time and radio signal receiving time, which is broadcast by the satellites.
To do that calculation, of course, the GPS unit time has to be in-sync/the same with the GPS satellite time.
I read that GPS units first make a (false) distance calculation (or X,Y,Z coordinate) to three satellites, and then make the adjustment from a fourth satellite to make all the distance radii intersect at a single point. How exactly does a GPS unit do this?
I read that it achieves this by the means of pseudo-random code; how?