Understanding GPS: Difference between revisions
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===Earth is a rock=== | ===Earth is a rock=== | ||
The Earth is not spherical. Neither is it an ellipsoid, although we use an ellipsoid to approximated it. The Earth is actually a geoid, or shaped like a rock. | |||
Image:Geoid.gif | |||
===The System=== | ===The System=== | ||
Revision as of 17:47, 23 October 2006
The US GPS system is a collection of 24 satalites placed in a geosyncronous orbit around the earth. By knowing exactly where these satalites are with regard to the earth, comunication with a GPS device can be trilaterated to calculate it's postition as well.
Earth is a rock
The Earth is not spherical. Neither is it an ellipsoid, although we use an ellipsoid to approximated it. The Earth is actually a geoid, or shaped like a rock.
Image:Geoid.gif
The System
The standard for this is constantly in a state of flux, but at this moment, the system is defined by the WGS-84 standard.
[WGS84 Implementation Manual]
Europe has been working on developing their own Galileo GPS system, mainly in the interest on not relying on a US system that can be locked out as a negotiating tactic. Russia uses it's own GLONASS system.
Mathmatics
