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Trail Guide
 Owner’s Manual 
41
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 GPS > 
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 GPS I
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U
NDERSTANDING
 GPS
The Global Positioning System (GPS) is a satellite-based 
navigation system made up of a network of 24 satellites placed 
into orbit by the U.S. Department of Defense. GPS was originally 
intended for military applications, but the government made the 
system available for civilian use in the 1980s. GPS works in any 
weather condition, anywhere in the world, 24 hours a day. There 
are no subscription fees or setup charges to use GPS.
GPS satellites circle the earth twice a day in a very precise orbit 
and transmit signal information to Earth. The GPS receiver in 
your Trail Guide takes this information and uses triangulation 
to calculate your exact location. Essentially, the GPS receiver 
compares the time a signal was transmitted by a satellite with the 
time it was received. The time difference tells the GPS receiver 
how far away the satellite is. With distance measurements from a 
few more satellites, the receiver can determine your location and 
display it on the Map page.
A GPS receiver must be locked on to at least three satellites 
to calculate a 2D location (latitude and longitude) and track 
movement. With four or more satellites in view, the receiver can 
determine your 3D location (latitude, longitude, and altitude).
After your location has been determined, the GPS unit can 
calculate other information, such as speed, bearing, track, trip 
distance, distance to destination, sunrise and sunset, and time.
WAAS is a system of satellites and ground stations that provide 
GPS signal corrections, giving you even better position accuracy. 
WAAS corrects for GPS signal errors caused by ionospheric 
disturbances, timing, and satellite orbit errors, and it provides vital 
integrity information regarding the health of each GPS satellite.
The GPS Information Page
The GPS Information page provides a visual reference of GPS 
receiver functions, including current satellite coverage, receiver 
status, and position accuracy. To access this page, press MENU
highlight Settings, and press OK. From the Settings page, 
highlight GPS Info and press OK
GPS satellites are positioned throughout the sky. As soon as you 
turn on your Trail Guide, it attempts to acquire satellite signals. 
The sky view area on the GPS Information page displays which 
satellites are currently in your area.