GPS Satellite System
According to REI, GPS technology uses the signals from three or more satellites orbiting the Earth to locate the latitude, longitude and altitude of any position on Earth. A GPS-only system typically sees accuracy from 4 to 20 meters.
Wide Area Augmentation System (WAAS)
WAAS is a system of ground-based stations that monitor the signals from satellites and correct for any errors in the signals. According to REI, a WAAS-enabled GPS system can obtain accuracy of 3 meters or less in ideal conditions.
Differential GPS
Hiker checking a location on a GPS.
GPS users can get even better accuracy with a differential GPS (DGPS) system. The DGPS corrects for many of the sources of GPS error.
Factors Influencing Accuracy
A GPS unit's accuracy is dependent on getting clear signals from multiple satellites. Obstructions such as dense forest or tall canyon walls can make GPS readings unreliable.
Improving Accuracy
GPS unit accuracy can be improved with better reception. Choose a GPS unit with a high-sensitivity processor chip and a high-quality antenna for better accuracy.
