Pharos Science & Applications 505 - Manual (Page 48)

Chapter 5: Additional Information
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How often does the GPS satellite update the signals? How
many satellites are required for a successful positioning?
The GPS signals are transmitted every second. Based on the Pythagorean
Theorem, it takes at least three satellites for the 2D positioning, and four
satellites for the 3D positioning. In the mountain area, the 3D positioning is
required for the accurate data.
Why does the Pocket PC fail to find the COM port for GPS?
1. Check if the GPS power is turned on.
2. Check if the COM port setting (COM1) and baudrate setting (4800) is
set correctly in Navigation program.
3. Check if the COM port is used by other software (especially for the
devices installed with two or more map programs).
4. Check if the COM port is used by some driver (for example, USB driver).
What are the factors that may affect the reception of GPS
signals?
1. The signal interruptions from the SA satellite of the Department of
Defense of the United States.
2. The weather ( sunspots, low signal strength from the bad weather,
etc ).
3. Electromagnetic interruptions.
4. Coverings (buildings, back seats of the vehicles, window films or
metallic coverings).
Why do the GPS signals appear and then disappear?
1. The Pocket PC has insufficient power, or the AC adapter provides
insufficient current.
2. Check if the vehicle has coverings, such as window films.
3. The GPS receiver on the Pocket PC is damaged.
The volume is too low. How do I fix it?
1. Use the external speakers.