Garmin GPS 3 Manual

							Notice the information on the map display is slowly moving? That’s how it would
look in actual use as well. The background map information and nearby waypoints
will move across the screen, while your current position remains fixed in the center.
The other primary navigation screens are the Compass and Highway pages, with
the Compass Page appearing first in the sequence of main pages. 
To view the Compass Page, press PAGE.
The GPS III’s Compass Page provides graphic steering guidance to a destination
waypoint. The middle of the page features a rotating ‘compass ring’ that shows your
course over ground (track) while you’re moving, and a bearing pointer that indicates
the direction of the destination (bearing) relative to the course over ground. The com-
pass ring and pointer arrow work independently to show—at a glance—the direction
of your movement and the direction to your destination. If the arrow points up, you
are going directly to the waypoint. If the arrow points any direction other than up, turn
toward the arrow until it points up—then continue in that direction. The distance to
the next waypoint, time to the next waypoint and current speed  are displayed to the
right of the graphic compass display. To see how all this works on our simulated trip,
let’s head off course and watch the displays change.
To move off course / on course in simulator mode, use the LEFT/RIGHT
keys on the rocker keypad.
The background map moves
while keeping your current
position at the center of the
map display.
The Compass Page will also
guide you to your destination.
The rotating ‘compass ring’
shows the direction of travel
(track) and the arrow points
to your destination (bearing).
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SIMULATOR TOUR
Compass Page
Bearing
Pointer
Compass
Ring
User-selectable
data fields
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							To view the Highway Page, press PAGE.
The Highway Page provides a graphic highway display that shows your move-
ment relative to the desired course. The line down the middle of the highway repre-
sents your desired course. As you navigate toward your destination, the highway will
actually move, indicating the direction you’re off course. To stay on course, simply
steer toward the center of the highway. As you approach the waypoint, the highway
will end at the final destination. When the waypoint marker is at the bottom center
of the highway display, you’ve arrived at your destination. A track compass also
shows your current track directly above the highway display, making it easy to see at
a glance which way you’re headed.
The pointer arrow at the bottom of the page indicates the direction to the 
destination waypoint (bearing) relative to the direction you are moving (track). If the
pointer points straight ahead, you’re heading directly to the waypoint. If not, turn in
the direction of the pointer and the pointer will swing around, pointing straight
ahead as you begin moving toward the destination waypoint. Try moving on course/
off course again using the rocker keypad and watch as the highway display and bear-
ing pointer change.
That’s it! You’ve covered the basics and you’re ready to venture off on your own.
Operating the GPS III is just as simple as you’ve seen here in the Simulator Tour, but
in real applications you won’t need to change speed and track with the rocker key-
pad. That’s all done automatically utilizing information from the GPS satellites as you
move about.
Before ending the tour, try a few experiments of your own, such as going back
to the ‘HOME’ waypoint, retracing your steps utilizing the TracBack feature, or cre-
ating a few more waypoints. Use the Reference section of this manual for more ideas.
To end the Simulator Tour, turn the GPS III off with the red power key.
Use the LEFT/RIGHT keys on
the rocker keypad to move off
course / on course. To return
to your course, steer toward
the highway centerline.
When you reach your destina-
tion, the highway will end at
the waypoint marker. Also
note the ‘distance to next’
waypoint readout. If you pass
the waypoint the pointer will
swing around, pointing down.
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SIMULATOR TOUR
Highway Page
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							The GPS III’s Satellite Status Page provides a visual reference of various receiver
functions, including current satellite coverage, receiver operating mode, battery level
and position accuracy. As the receiver locks onto satellites, a signal strength bar will
appear for each satellite in view, with the appropriate satellite number (01-32) under-
neath each bar. The progress of satellite acquisition is shown in three stages:
• No signal strength bars— the receiver is looking for the satellites indicated.
• Hollow signal strength bars— the receiver has found the satellite(s) and is
collecting data.
• Solid signal strength bars— the receiver has collected the necessary data and
the satellite(s) is ready for use.
Each satellite has a 30-second data transmission that must be collected (hollow bar
status) before that satellite may be used for navigation (solid bar status). Once a fix has
been calculated, the GPS III will then update your position, track, and speed by select-
ing and using the best satellites in view. You can also access the GPS III’s contrast fea-
ture from this page.
To adjust the screen contrast:
1. Press LEFT or RIGHT on the rocker keypad to adjust the level of contrast, and press
ENTER to save the new contrast setting.
Sky View and Signal Strength Bars
The sky view and signal strength bars give you an indication of what satellites are
visible to the receiver, whether or not they are being used to calculate a position fix,
and the signal quality. The satellite sky view shows a bird’s-eye view of the position of
each available satellite relative to the unit’s last known position. The outer circle rep-
resents the horizon (north up); the inner circle 45º above the horizon; and the center
point directly overhead. 
The Satellite Status Page
shows where the satellites are
and how strong the signal is
from each one. A solid signal
bar means the satellite is
ready to use.
Use the LEFT/RIGHT keys on
the rocker keypad to adjust
the screen contrast. Press
ENTER to save the setting.
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REFERENCE
Satellite Status Page
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							You can use the sky view to help determine if any satellites are being blocked,
and whether you have a current position fix (indicated by a ‘2D Navigation’ or ‘3D
Navigation’ in the status field). You can also set the sky view to a ‘Track Up’ config-
uration, causing the top of the sky view to align along your current track heading.
When the receiver is looking for a particular satellite, the corresponding signal
strength bar will be blank and the sky view indicator will not be highlighted. Once
the receiver has found the satellite, a hollow signal strength bar will appear, indicat-
ing that the satellite has been found and the receiver is collecting data from it. The
satellite number in the sky view will appear highlighted. As soon as the GPS III has
collected the necessary data to calculate a fix, the status field will indicate a 2D or 3D
status. (For ‘2D’, you may need to enter your altitude. See page 30.)
Receiver Status
Receiver status is indicated at the top left of the page. The status will be shown
as one of the following conditions:
Searching— the GPS III is looking for any available satellites in view.
AutoLocate— the GPS III is initializing and collecting new almanac data. This
process can take up to 5 minutes, depending on the satellites currently in view.
Acquiring— the receiver is collecting data from available satellites, but has not
collected enough data to calculate a position fix.
2D Navigation— at least three satellites with good geometry have been locked
onto and a 2-dimensional position fix (latitude and longitude) is being calculat-
ed. ‘2D Diff ’ will appear when you are receiving DGPS corrections in 2D mode.
3D Navigation— at least four satellites with good geometry have been locked
onto, and your position is now being calculated in latitude, longitude and alti-
tude. ‘3D Diff ’ will appear when you are receiving DGPS corrections in 3D mode.
‘2D Navigation’ means the
GPS III has determined a hor-
izontal position (latitude/
longitude), but is unable to
determine altitude. Additional
satellites may be needed.
‘3D Navigation’ means the
GPS III has determined a hor-
izontal and vertical position
(latitude, longitude and alti-
tude). The receiver is ready
for navigation.
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REFERENCE
Satellite Status Page
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							Poor GPS Coverage— the receiver isn’t tracking enough satellites for a 2D or 3D
fix due to bad satellite geometry.
Not Usable— the receiver is unusable, possibly due to incorrect initialization or
abnormal satellite conditions. Turn the unit off and back on to reset, and reinitial-
ize the receiver if necessary.
Simulating Nav— the receiver is in simulator mode.
‘Need to Select Initialization’ Prompt
If no satellites are received for several minutes (or an insufficient number of satel-
lites are received to determine a position fix) a message will appear, prompting you to
initialize the receiver (see page 5). This allows you to specify a starting location from
which to search for satellites, or to enable the AutoLocate feature, and is useful if you
have traveled over 500 miles with the receiver off. (This message will automatically
appear when you first use your GPS III. The prompt may also appear during normal
use if the antenna is shaded or the unit is used indoors.)
Battery Level Indicator
The Satellite Status Page also features a battery level indicator, located to the left of
the sky view, which displays the strength of the unit’s batteries. The battery indicator
will not appear if the receiver is operating on external power.
NOTE: The battery level indicator is calibrated for alkaline batteries. NiCad and
lithium batteries will display the battery level differently due to voltage differences. To
display battery level accurately select the appropriate type, as described on page 69.
The GPS III features an internal 10-year lithium battery that will maintain the unit’s
memory when the receiver is not running off batteries or external power.
‘Poor GPS Coverage’ means
the receiver isn’t tracking
enough satellites for a position
fix. Check for obstructions,
such as trees, buildings, etc.
This message appears if a
position fix cannot be deter-
mined after several minutes.
After acknowledging the mes-
sage, select ‘Use Map’ or
‘AutoLocate’ from the
options list.
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REFERENCE
Satellite Status Page
#?
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							EPE and DOP
The Satellite Status Page also indicates the accuracy of the position fix, using
Estimated Position Error (EPE) and Dilution of Precision (DOP) figures. DOP mea-
sures satellite geometry quality (i.e., number of satellites received and where they are
relative to each other) on a scale from one to ten. The lowest numbers are the best
accuracy and the highest numbers are the worst. EPE uses DOP and other factors to
calculate a horizontal position error, in feet or meters.
Screen Backlighting
The GPS III’s backlight feature illuminates the display and keypad for a user-
defined interval (the default is 15 seconds) after the last key press. There are three
stages of backlighting. When backlighting is on, a bulb icon will appear at the bot-
tom left of the sky view. To adjust the duration of the screen backlighting, refer to
the operation setup section (see p. 69). 
To turn the screen backlighting on:
1. Cycle through the three levels of backlight by repeatedly pressing the red power key.
To turn the screen backlighting off:
1. Press the red power key. Whenever the GPS III’s backlighting is off, the bulb icon dis-
appears from the Satellite Status Page.
Satellite Status Page Options
Many features of the GPS III are menu driven. Each of the main pages has an
options menu, allowing you to custom tailor the corresponding page to your prefer-
ences and/or select special features which specifically relate to that page.
To display the Satellite Status Page Options, press MENU (with the
Satellite Status Page displayed).
When screen backlighting is
on, a bulb icon will appear in
the lower-left corner of the
Satellite Status Page.
The Satellite Status Page
Options allow you to enable
the built-in simulator, change
the sky view orientation or
initialize the receiver.
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REFERENCE
Satellite Status Page
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							The following Satellite Status Page options are available:
Start Simulator— allows you to activate the GPS III’s built-in simulator mode. If 
‘Start Simulator’ is selected, ‘Stop Simulator’ will appear as an option instead.
To activate (deactivate) simulator mode:
1. Highlight ‘Start Simulator’ (or ‘Stop Simulator’) and press ENTER.
2. Highlight ‘Yes’ and press ENTER.
Track Up— changes the sky view display from ‘North Up’ orientation to align to 
current direction of travel (track). If ‘Track Up’ is selected, ‘North Up’ will appear 
as an option instead.
To change the sky view orientation:
1. Highlight ‘Track Up’ (or ‘North Up’) and press ENTER.
AutoLocate— forces the GPS III to search for any available satellite(s) to determine 
its position. This option is useful if you’ve relocated a long distance (>500 mi.) 
from the last location the GPS III was used.
To select AutoLocate, highlight ‘AutoLocate’ and press ENTER.
Initialize Position— allows you to designate your approximate position in order 
to speed up satellite acquisition. This option may be used in lieu of ‘AutoLocate’, 
above.
To initialize your starting position:
1. Highlight ‘Initialize Position’ and press ENTER.
2. Designate your approximate position on the map using the rocker keypad and press 
ENTER. (You may wish to use the IN/OUT zoom keys to adjust the level of detail
displayed, as you determine your approximate position.)
‘AutoLocate’ forces the receiv-
er to search for all satellites
(twelve at a time) until
enough satellites are found to
determine a position.
‘Initialize Position’ is used to
designate your approximate
position directly on the map
display. The receiver uses this
information to determine
which satellites should be in
view.
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REFERENCE
Satellite Status Page Options
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							With 2D coverage, you will
need to enter your approxi-
mate altitude. Without an
approximate altitude, your
position error can be substan-
tial.
The Position Page shows you
where you are, what direction
you’re heading and how fast
you’re going.
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REFERENCE
Set 2D Altitude— allows you to designate your approximate altitude, when the 
GPS III is acquiring satellites or navigating in 2D mode. By default, 2D naviga-
tion will attempt to use the last known altitude. If the altitude shown is off by 
several hundred feet (or more), manually entering your approximate altitude will 
enable the receiver to more accurately determine a position fix. 
To enter an altitude:
1. Highlight ‘Set 2D Altitude’ and press ENTER.
2. Enter your approximate altitude using the rocker keypad, and press ENTER.
Position Page
The second page in the GPS III’s main page sequence is the Position Page. This
page shows you where you are, what direction you’re heading, and how fast you’re
going, and it’s most useful when you are traveling without an active destination way-
point. The graphic heading display at the top of the page indicates the direction
you’re heading, or track, only while you’re moving.
Directly below this display are the speed, average speed, trip timer, trip odome-
ter and sunrise/sunset fields (default). The sunrise/sunset times indicated are for your
present position. These times, and the current time display in the lower-right corner,
can be displayed in local or UTC (universal) time. The lower left-hand corner of the
page shows your current latitude and longitude in degrees and minutes (default). The
GPS III uses this basic information to mark exact positions as waypoints, which help
guide you from one place to another. Average speed, sunrise and sunset times (at
your present position) also appear on the Position Page (as default selections). Units
of measure and the position readout are selectable from the Main Menu, as outlined
on page 63. ‘Trip Computer’ functions—such as average speed, max speed, trip
odometer and trip timer—can each be reset from the Main Menu, as described on
page 64.
Satellite Status Page Options
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							Many features of the GPS III are menu driven. Each of the main pages has an
options menu, allowing you to custom tailor the corresponding page to your prefer-
ences and/or select special features which specifically relate to that page.
To display the Position Page Options, press MENU (with the Position
Page displayed).
The following options are available:
Average Position— allows you to average position samples over time and save the 
averaged result as a waypoint. Averaging reduces the effects of selective availabili-
ty on position error and results in a more accurate position reading.
To average position samples and save the result as a waypoint:
1. Highlight ‘Average Position’ and press ENTER. The Average Position Page will appear. 
Observe the ‘Estimated Accuracy’ and ‘Measurement Time’ fields.
2. When the ‘Estimated Accuracy’ and/or ‘Measurement Time’ figures reach the desired 
value(s), highlight ‘Save’ and press ENTER. (To cancel the averaging function, highlight
‘Discard’ and press ENTER.) 
3. The New Waypoint Page appears with a three-digit number assigned as a name
for the new waypoint. To save the waypoint with this name, highlight ‘Done’ and 
press ENTER. Or,
4. To change the waypoint name, highlight the waypoint name field and press ENTER. 
Use the rocker keypad to enter a new name for this waypoint and press ENTER when
finished. Highlight ‘Done’ and press ENTER to save the waypoint. 
The Position Page Options
allow you to average position
samples and save the result as
a waypoint, change data fields
or restore factory defaults.
When averaging positions to
create a waypoint, observe the
‘Estimated Accuracy’ and
‘Measurement Time’ figures.
When they reach the desired
value(s), highlight ‘Save’ and
press ENTER.
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REFERENCE
Position Page Options
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							Change Fields— allows you to choose the data displayed on the six user-selec-
table data fields. Available data types are: Altitude, Average (Avg) Speed, Battery 
(Bat) Timer, Max Speed, Odometer, Speed, Sunrise (at present position), Sunset 
(at present position), Track, Trip Odometer, Trip Timer, User Timer and Voltage. 
See page 85 for descriptions of navigation terms.
To change a data field:
1. Highlight ‘Change Fields’ and press ENTER.
2. Highlight the data field you wish to change (using the rocker keypad) and press ENTER.
3. Select the type of data you want to appear on this field and press ENTER.
Restore Defaults— resets all data fields to the factory default settings.
To restore the factory default settings, highlight ‘Restore Defaults’ and
press ENTER.
‘Change Fields’ allows you to
custom tailor the information
that appears on the Position
Page. Select the desired data
type from the list.
‘Restore Defaults’ will over-
ride any data field changes
you’ve made to the Position
Page, reverting back to the
factory default settings.
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REFERENCE
Position Page Options
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