How gps works.

• Localización: Scientific American, ISSN 0036-8733, Vol. 290, Nº. 5, 2004, págs. 93-93
• Idioma: inglés
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• Resumen

  • The article presents diagrams illustrating the Global Positioning System (GPS), a radio-based worldwide navigation system comprising two dozen satellites and associated ground stations. The topics covered are intersecting spheres, timing signals, PRN codes, and synchronized clocks. Gauging the distance to a satellite requires timing how long it takes for a satellite signal to arrive at a receiver. To understand how PRN codes aid in measuring distance, consider this analogy: suppose that both the satellite and the receiver started playing the same song--the PRN code--at the same time. To synchronize the clocks in orbit with those on the earth and thus compensate for the timing error, GPS must make a fourth satellite measurement.