Originally Posted by
N1234
This is correct. Most aviation receivers require line of sight to 5 satellites. 3 for position incl alt. 1 for time reference and 1 for RAIM.
Not my understanding. My understanding is that it's a differential math equation with 4 equations and 4 unknowns, solving for 1 time that satisfies all equations. Sats traveling thousands of miles/hr are essentially "dumb", sending out their atomic time. Receiver gets atomic time from 4 different sats, but all the times are different due to the difference in distance. Receiver must solve for distances and time in those 4 equations, pseudo-ranging. This is 3d position. Receiver knows what time it is where it is located with no delay/distance error because it's constantly solving this equation.