Global Positioning System (GPS)
Overview
Global Positioning System (GPS) is a satellite-based navigation system that provides location and time information anywhere on Earth, commonly used for mapping and geospatial data collection. GPS is operated by the U.S. Space Force and is one of several Global Navigation Satellite Systems (GNSS).
Key Concepts
Satellite constellation consists of 24+ satellites orbiting Earth. Trilateration calculates position from distances to multiple satellites. Pseudorange is the calculated distance from receiver to satellite. Ephemeris is satellite orbital data broadcast to receivers. HDOP/PDOP are dilution of precision measures of position quality. Differential GPS (DGPS) improves accuracy using ground reference stations.
GPS Accuracy
| Mode | Horizontal Accuracy |
|---|---|
| Standard (civilian) | 3-5 meters |
| WAAS-enabled | 1-3 meters |
| Differential GPS | 0.5-1 meter |
| RTK GPS | 1-2 centimeters |
| Survey-grade | Sub-centimeter |
GNSS Systems
- GPS (United States)
- GLONASS (Russia)
- Galileo (European Union)
- BeiDou (China)
Appendix
Created: 2025-12-13 | Modified: 2025-12-13