GPS
(Global Positioning System)
Technology Overview
A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between the transmission and reception of each GPS microwave signal yields the distance to each satellite since the signal travels at a known speed. The signals also carry information about the satellites' locations. By determining the position of, and distance to, at least three satellites, the receiver can compute its position using trilateration. Receivers typically do not have perfectly accurate clocks and therefore track one or more additional satellites to correct the receiver's clock error.
Applications
GPS has become a widely used aid for navigation worldwide, and a valuable tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including the scientific study of earthquakes and the synchronization of telecommunications networks.
Key Parameters
| GPS | |
|---|---|
| Frequency | L1 1575.42 MHz
L2 1227.6 MHz |
| Modulation | BPSK |
| Channel Bandwidth | 20.46 MHz |
| Number of Channels | up to 32 satellites |
| Peak Data Rate | 50 bit/s |
| Max. Speed | ca. 1600 km/h |
Standardization
Developed by the United States Department of Defense, GPS is officially named NAVSTAR. The satellite constellation is managed by the United States Air Force 50th Space Wing.
