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Article: Car 54, where are you? (Auto-Trac Inc. in Dallas, Texas, uses Global Positioning System to track motor vehicles) (Column)
- Article from:
- Mechanical Engineering-CIME
- Article date:
- April 1, 1994
- Author:
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Copyright informationCOPYRIGHT 1994 American Society of Mechanical Engineers. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Navigating by points of reference in the sky is an arcane science. Modern orientation techniques involving celestial position are based on satellites that emit radio waves. This is the logic behind the Global Positioning System (GPS), a constellation of 24 satellites in geosynchronous orbit around the earth. They were launched and are maintained by the US. Department of Defense.
The accuracy of GPS data depends on how the receiver is tuned. Military devices tuned to the GPS P-Code frequency can calculate position to within a few meters. These types of navigational aids enable a cruise missile, for example, to be put through a particular window of an office building. Civil ...
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