In 1995 I worked for a GPS developer, Avcan Avionics, and we built software that would allow tundra devices in the Arctic to travel between a supply depot and remote mines in 100% whiteout conditions, navigating only by a path that had been loaded into GPS. Our variant of this process was called "Differential GPS" - basically leaving a base station in single location for 24+ Hours where it would eliminate the S/A error which was presumably random.
We successfully navigated a car down a twisting road, about 10' wide, without looking out the window, so it was a useful mechanism. It became less important, of course, once the US Government removed the S/A error from the GPS signal and the commercial use of GPS took off.
We successfully navigated a car down a twisting road, about 10' wide, without looking out the window, so it was a useful mechanism. It became less important, of course, once the US Government removed the S/A error from the GPS signal and the commercial use of GPS took off.