GPS is a highly accurate navigation system using signals from satellites to determine a location on the Earth’s surface, irrespective of weather conditions.
It is dependent on GPS satellites high above the Earth which transmit signals containing the time and location of the satellite. Any ground-based receiver which receives signals from four or more GPS satellites can use navigation equations to calculate its location on the Earth’s surface. Constant signaling can then update speed and direction information for moving receivers.

GPS was originally developed for military use but since the 1990s has been open for civilian use and is now used in such common applications as mobile phones, car navigation systems, and of course surveying and mapping.

Work includes GPS receiver selection and network design, GPS planning and use in map update and surveys, GPS usage in remote sensing and photogrammetry for rectification.