About Gps - Rand McNally IntelliRoute TND 500 User Manual

About GPS

The Global Positioning System (GPS) is a constellation of satellites that a GPS
receiver uses to calculate geographical positions. To determine a position, data
from at least three satellites is required. To determine altitude, the data from 4
or more satellites is required. Accuracy of the positioning varies from 10 feet
to several hundred feet, depending on vehicle placement and the surrounding
environment
Geographical terrain (such as mountains), man-made structures (such as
highway overpasses, bridges and tall buildings), as well as weather can interfere
with the GPS signal. For best GPS reception, position the IntelliRoute® TND™
500 and mount with a clear line of sight to the sky.
Some vehicles may have a limited view of the sky due to metal sun shields, or
a metallized windshield coating. If your unit does not appear to receive signals
well inside your vehicle but works well outside, contact Rand McNally for an
available external antennae.
Map data used by the IntelliRoute® TND™ 500 includes the geographical
coordinates for address locations and Points Of Interest (POIs). With GPS
reception, your device calculates a route to your selected location.
Rand McNally IntelliRoute ® TND TM 500 User's Guide 2