Global positioning system (gps), Gps overview – Sierra Wireless EV-DO User Manual
Page 84
Rev 3.0B Feb.08
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9
9: Global Positioning System
(GPS)
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The PinPoint‐E is equipped with a Global Positioning System
receiver (GPS) to ascertain its position and track the
movements of a vehicle or other devices which move. The
PinPoint‐E relays the information of its location as well as
other data for use with tracking applications.
Tracking Applications used with Sierra Wireless PinPoint line
modems:
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Air‐Trak
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Track Your Truck
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Track Star
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DeLorme Street Atlas USA
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Microsoft Streets and Trips
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CompassCom
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Zoll Data
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and many more...
GPS Overview
The Global Positioning System (GPS) is a satellite navigation
system used for determining a location and providing a highly
accurate time reference almost anywhere on Earth. The US
military refers to GPS as Navigation Signal Timing and
Ranging Global Positioning System (NAVSTAR GPS).
GPS consists of a “constellation” of at least 24 satellites in 6
orbital planes. Each satellite circles the Earth twice every day
at an altitude of 20,200 kilometers (12,600 miles). Each satellite
is equipped with an atomic clock and constantly broadcasts
the time, according to its own clock, along with administrative
information including the orbital elements of its motion, as
determined by ground‐based observatories.
A GPS receiver, such as the PinPoint‐E, requires signals from
four or more satellites in order to determine its own latitude,
longitude, and elevation. Using time synced to the satellite
system, the receiver computes the distance to each satellite