10. How GPS Works… 1 Distance from satellites needs to be known 4 Correct for atmospheric and ionospheric errors 3 Need to know Satellite position 2 Accurate (Atomic) Clocks are required
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26. Internet Map Server on notebook computer with wireless access port. Field workers: Pocket PC, GPS, and wireless card. Wi-Fi wireless communication (up to 300 feet)
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31. Multipath means that the same radio signal is received several times through different paths. For instance, a radio wave could leave a satellite and travel directly to the receiver, but it also bounces off a building and arrives at the receiver at a later time. Multipath Errors
32. The internal satellite and receiver clocks have limited accuracy, and they are not precisely synchronized. Since position computations are highly dependent on accurate timing information, small clock errors can cause significant errors in position computations. Clock Limitations
34. Satellite Geometry/Shading This refer to the relative position of the satellite at any given time.Ideal satellite geometry exists when the satellite are located at wide angle relatives to each other.Poor geometry results when the satellite are located in a line or in a tight grouping
