GPS receivers can only be accurate if they know the location of the satellites they are tracking. The GPS satellites travel in predictable orbits, and the satellites’ positions are known in advance. The GPS receiver stores this information in an almanac (a sort of bus schedule), updated every two hours and valid for four hours. For the GPS receiver to track the satellites, it must receive the ephemeris from a GPS satellite. GPS receivers must have a strong and clear signal. Despite being a wonderful tool, GPS receivers are good. Since they rely on a network of satellites ...Read more
