II Morrow Inc. 920 GPS - Manual (Page 12)

Section A - Introduction to Satellite Navigation
What
is GPS? The Global Positioning System (GPS) is a
constellation of 24 satellites in six orbit lanes
10,898nm above the earth. Each satellite orbits
the earth twice in 24 hours.
What
Does the
GPS
Receiver
Do? The Apollo handheld GPS receiver is a
portable position sensor and computer which
receives signals from the GPS satellites to
provide highly accurate position information.
With an extensive database of waypoint
information and the ability to allow the user to
create up to 2,000 “customized” waypoints, the
Apollo handheld GPS receiver gives you the
ability to navigate to any point in the world
with unsurpassed accuracy.
How Does
GPS
Work? GPS satellites transmit complex streams of data
the GPS receiver uses to find the satellite’s
position,
the current time, and other
information. With signals from three or more
satellites, the receiver can calculate latitude and
longitude; with four or more satellites, altitude
can also be calculated. For optimal access to
satellite signals, the GPS antenna should have
an unobstructed view of the entire sky. The
internal antenna is located in the top portion of
the Apollo handheld GPS receiver.
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