Garmin GPS 92 - Manual (Page 12)

The Global Positioning System (GPS) is a constella-
tion of 24 satellites which circle the earth twice a day in
a very precise orbit and transmit information back to
Earth. This information includes operational status and
orbital location of each satellite in the system. The GPS
92 must continuously “see” at least three of these satel-
lites to calculate your position and track your movement.
At times, additional satellites may be needed to determine
a position.
By using an almanac (a timetable of satellite numbers
and their orbits) stored in the receiver’s memory, the GPS
92 can determine the distance and position of any GPS
satellite and use this information to compute your posi-
tion.
Your GPS receiver can only see satellites above the
horizon, so it needs to know what satellites to look for at
any given time. To use this almanac data, your GPS 92
needs to either be told its general location (be “initial-
ized”) or given the opportunity to find itself. Once you
initialize the unit to a position, it will typically compute a
fix within a few minutes.
Initialization is only necessary under the following
conditions:
• The first time you use your receiver (new from
the factory).
• After the receiver has been moved over 500
miles (with the power off) from the last time
you used it.
• If the receiver’s memory has been cleared and
all internally stored data has been lost.
Because the GPS 92 relies on satellite signals to
provide you with navigation guidance, the receiver needs
to have an unobstructed, clear view of the sky for best
performance. In a nutshell, the GPS receiver’s view of the
sky will generally determine how fast you get a position
fix—or if you get a fix at all. GPS signals are relatively
weak and do not travel through rocks, buildings,
hangars, or heavy tree cover, so remember to keep a clear
view of the sky at all times for best performance.
Hold the receiver at arms
length and rotate the
antenna perpendicular to
the ground.
Welcome Page
What is
GPS?
Getting
Started
6
92 manual 4/15/98 3:48 PM Page 6