Garmin GPS 40 - Manual (Page 9)

3
Introduction
GPS Overview
How Does GPS Work?
1. A constellation of satellites transmit signals to earth, containing precise
position and time information for each satellite.
2. Your GPS unit searches for these sig-
nals, and ‘locks on’ to as many as
eight satellite signals for con-
tinuous tracking.
3. Once the receiver is
locked onto a set of
signals, it can determine
how far away each satellite
is by measuring the time it
takes to receive each signal. By
knowing the distance and position of
3 or more satellites, the GPS receiver
can then calculate your position by using
a technique called satellite ranging. This
calculation, or triangulation, simply mea-
sures your position in reference to a set
of known objects (the GPS satellites).
4. As the GPS receiver tracks satellites, it
will continuously update your position
and provide track and speed information
while you’re moving.
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