GLOBAL POSITIONING SYSTEM (GPS)
GPS is a positioning system that exploits dedicated hardware (e.g. satellites) for improved performance in localization capabilities
The concept is to use lateration in combination with ToA using satellites with known positions
GPS satellites needs to have a perfect synchronized clock, can achive an error of around 300 meters
DIFFERENTIAL GPS
to reduce the error range of GPS a base station with a fixed position is used to correct the error in the satellites measures