Error analysis for the Global Positioning System: Difference between revisions

Revision as of 21:39, 24 September 2011

Revision as of 21:45, 24 September 2011

Line 264:

== Relativity ==

[[Image:Orbit times.pngsvg|thumb|right|Satellite clocks are slowed by their orbital speed but sped up by their distance out of the Earth's gravitational well.]]

A number of sources of error exist due to [[Theory of relativity|relativistic]] effects<ref name=errors>Webb (2004), p. 32.</ref> that would render the system useless if uncorrected. Three relativistic effects are the time dilation, gravitational frequency shift, and eccentricity effects. For example, the relativistic time ''slowing'' due to the speed of the satellite of about 1 part in 10¹⁰, the gravitational time dilation that makes a satellite run about 5 parts in 10¹⁰ ''faster'' than an Earth based clock, and the [[Sagnac effect]] due to rotation relative to receivers on Earth. These topics are examined below, one at a time.