GPS Accuracy

The accuracy of the GPS signal itself is about 5 meters. However, using differential GPS and other error-correcting techniques, the accuracy can be improved to about 1 cm over short distances.

Differential GPS (DGPS)

DGPS is an enhancement to GPS that uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions.

For more information on GPS please visit the Ordnance Survey website.