Garmin GPS 3 Manual

GETTING STARTED
Batter y Installation
3
The GPS III operates on 4 AA batteries (not included), which are installed at the
base of the unit. These batteries provide up to 8 hours of continuous use.
Rechargeable NiCad or lithium batteries may also be used.  
NOTE: The on-screen battery level indicator is calibrated for alkaline batteries,
and will not be accurate when using NiCad or lithium batteries (see page 69).
To install the batteries:
1. Flip up the metal ring at the base of the unit, and turn the...

What is GPS?
GETTING STARTED
The Global Positioning System (GPS) is a system of 24 satellites which circle the
earth twice a day in a very precise orbit and transmit information to earth. The GPS
III must continuously “see” at least three of these satellites 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 III can...

Once the GPS III has calculated a position fix, you’ll usually have anywhere from
five to twelve satellites in view. The receiver will then continuously select the best 
satellites in view to update your position. If some of the satellites in view get blocked
or “shaded,” the receiver can simply use an alternate satellite to maintain the position
fix. Although a GPS receiver needs four satellites to provide a three-dimensional 
(3D) fix, it can maintain a two-dimensional (2D) fix with only three...

This usually provides a position fix in 1 minute. You’ll know you have a fix when
the unit automatically transitions from the Satellite Page to the Map Page (shown
left). Your receiver is now ready to use!
To turn the unit off:
1. Press and hold the red power key for 1 second. 
Troubleshooting
If you have trouble initializing or getting a position fix, check the following:
• Does the receiver have a clear view of the sky?
If there are large buildings or mountains, or if there is heavy tree cover, the...

To turn the GPS III back on, press and hold the red power key.
The GPS III features six main pages which are linked together in a chain. You can
quickly scroll through the pages in either direction using the PAGE or QUIT keys. Let’s
briefly tour each of these pages in order to give you some insight into how they help
you navigate. We’ll go over all of them in more detail in the reference section.
Press the PAGE key to move
through each of the main
pages in normal fashion.
Press the QUIT key to
sequence...

Let’s start with the Satellite Status Page, which is the page you’ll view while your
unit is getting a position fix. If you’re not already on this page, press PAGE or QUIT
until it appears. The Satellite Status Page shows you status information that helps
you understand what the receiver is doing at any given time, and it’s a page that
you’ll want to occasionally refer back to as you use your unit. It features a sky view
of available satellites, corresponding signal strength bars, the status of your...

The Position Page shows you where you are, what direction you’re heading, and
how fast you’re going—and it’s the page you’ll want to use when you don’t have a 
destination selected.
A graphic compass display at the top of the page shows your direction of travel
(track) while you’re moving, while six user-selectable data fields below display your
current speed, average speed, trip odometer, trip timer, and sunrise/sunset times at
your current position. “User-selectable” means you can change them to...

The Map Page shows your movement using a real-time track log (an electronic
breadcrumb trail that appears directly on the map as you’re traveling), and your 
present position as a pointer icon in the center of the map. The Map Page also shows
any nearby lakes, rivers, highways and towns.  Use the zoom keys (IN and OUT) to
adjust the map to the desired scale.
To change the map scale:
1. Press the IN zoom key to select a smaller scale and more detail for a smaller area.
2. Press the OUT zoom key to select...

The GPS III features two different navigation pages: Compass and Highway. The
Compass Page is first. This page provides graphic steering guidance to a destination
waypoint, with an emphasis on the bearing to your destination and current direction
of travel. (The Highway Page places greater emphasis on the straight-line desired
course and the distance and direction you are off course.) The middle of the page fea-
tures a rotating ‘compass ring’ that shows your course over ground (track) while you’re...

The GPS III’s Highway Page also provides graphic steering guidance to a destina-
tion waypoint. As you head toward your destination, the middle of the screen pro-
vides visual guidance to your waypoint on a moving graphic “highway.” Your present
position is at the bottom center of the highway display. The line down the middle of
the highway represents your desired course. As you navigate toward a waypoint, the
highway will actually move—indicating the direction you’re off course. To stay on
course,...