Garmin ETREX Installation guide

Figure 1: The buttons as they appear
on the GPS unit.
PAGE
POWER
UP
ENTER
DOWN
BASIC INSTRUCTIONS FOR TAKING A GPS READING WITH A
GARMIN ETREX UNIT
See below (ADVANCED INSTRUCTIONS) for a more in-depth wal through. Review these instructions
prior to going out in the field. Please ta e readings for annual populations, new populations, and populations
that have dramatically changed in size. We suggest ta ing new GPS readings of even stable, perennial plant
populations every 2-3 years to correct for possible past errors and to provide a comparison with past
readings.
Buttons:
•
••
• POWER allows you to turn the unit on or off.
•
••
• PAGE allows you to move through the four
different GPS screens
•
••
• UP/DOWN allows you to move thru menus,
increase or decrease settings, flip through options
•
••
• ENTER allows you to select an option or open a
menu
To Turn the GPS Unit On Off:
• Press the POWER button. (Please do not forget
to turn the unit off whenever it is not in use as the batteries
run down quic ly. POC uses rechargeable batteries.)
• You will get a message, “Wait…tracking satellites”(A good signal needs 4 satellites—ta es up to 5
minutes)
• Getting a good signal:
o Moving around, especially in a straight line, helps the satellites locate you faster
o If you are under a dense canopy, it helps to trac satellites in a nearby open area first, then
bring unit (with the power still on) bac to the plant population
• Accuracy: GPS unit will show accuracy at the top of the screen when you first turn on the unit
• Try to get about 3-8m accuracy in open areas (if the error is a very large number at first, eep the unit
on and wait a few minutes for the error to reduce as you wal around)
To Take a Reading (see diagram in Monitoring Guidelines for where to take readings):
• Press PAGE button again until you return to the MENU screen
• Highlight MARK using the UP DOWN buttons
• Hold GPS unit at a place you want to take a reading, press ENTER
• Record the reading on the Monitoring Form—ºN is the top line (7 digit number) and ºW is the
bottom line (7 digit number). The northerly reading corresponds to latitude and the westerly reading
corresponds to longitude. The POC Units are set up to read in the Decimal Degrees format with datum
NAD27 CONUS (see p. 3 if you don’t now the current settings on your unit).
• If you press ENTER when “OK” is selected, the GPS unit will automatically create a Waypoint and
give it a title such as 001, 002, 003, etc. It may be helpful to write down this waypoint title, in order to
be able to access it later on. This way, you can see the coordinates again if you didn’t record them
immediately.

Menu screen
Compass
Waypoints
Map screen
ADVANCED INSTRUCTIONS FOR USING A GARMIN ETREX
Things to Know about the Garmin eTrex Unit:
•
••
• Screens
o The GPS unit has 4 main screens and you can flip between them with the
PAGE button.
o First Screen – Main screen


 Shows signal accuracy, the number of satellites to which the receiver
is connected, and the signal strength of each satellite connection
o Second Screen – Map


 Shows your current position on a map with an arrow pointing north


 Trac s your movements with a trail


 Can view the location of waypoints and see the direction you need to
travel to reach a point


 Options:
• UP button will allow you to zoom out
• DOWN button will allow you to zoom in
o Third Screen – Compass


 Top of the compass shows your direction of travel


 Can show the direction of a waypoint and the distance to that point


 UP/DOWN buttons will allow you to flip through display options
• Location
• Sunrise
• Sunset
• Trip time
• Trip odometer
• Speed
• Average speed
• Max speed
• Heading
• Bearing
• Elevation
o Fourth Screen – Menu


 Scroll through the menu with UP/DOWN buttons and push ENTER
to open an option


 Mark
• Mar a waypoint
• See current fixed location for recording purposes
• Enter a GPS coordinate to find


 Waypoints
• View, delete or navigate to a waypoint
• Thin of waypoints as you would a visual mar er on a
landscape; you can navigate to them or use them as a
position reference


 Route
• Ma e a route of travel with waypoints


 Tracks
• Clear, save, or open previous paths of travel
• Trac s are continually logged while a GPS unit is on and has
an accurate reading


 Setup
• Change the Time format
• Change the Display contrast to ma e the screen easier to
view
• Change the GPS Units of measurements (see below in “Types of data”)
o Position format
o Map datum
o Units
o North reference
• Interface allows you to change the GPS data exchange formats if you are using
cables to connect your GPS with another unit (e.g. computer)

• System allows you to see the unit’s software
•
••
• Types of data
o Coordinate systems are different formats used for recording a location (*** denotes POC’s
preferred system)


 Degree Decimal (e.g. dd.ddddd N) ***


 Degree Minute Second (e.g. dd°dd'dd.dd" N)


 UTM (e.g. dddddd)


 Minute Decimal (e.g. dd°dd.ddd)
o Datum is the way the data are projected onto the earth, sort of li e a grid system used as a
reference point for measurements (*** denotes POC’s preferred system)


 NAD 27 ***


 WGS-84 (NAD-83)
•
••
• Batteries
o GPS units use a great deal of power and can drain batteries very quic ly
o Turn off the unit when you no longer need it
o POC uses rechargeable batteries, so don’t throw batteries away
o POC provides an extra set in each case
To Check Adjust Settings before Taking a Reading (crucial before recording coordinates):
• Press PAGE button three times—you are now in the MENU screen
• Highlight “SETUP” using the UP DOWN buttons and then press ENTER; repeat this process for the
next screen when highlighting “UNITS”
• There are three settings: “POSITION FRMT,” “MAP DATUM,” “UNITS” and “NORTH REF”
• Select “POSITION FRMT,” and using the UP DOWN buttons highlight “hddd.ddddd*,”
• Press ENTER to select this option (the default format for POC is Decimal Degrees)
• Select “MAP DATUM”, and using the UP DOWN buttons highlight “NAD27 CONUS,” press
ENTER
• Select “UNITS,” and using the UP DOWN buttons highlight “METRIC,” press ENTER
• Select “NORTH REF,” and using the UP DOWN buttons highlight “TRUE,” press ENTER
To Insert a Previous Location or Create a Waypoint:
In order to relocate your population, you will need to enter the coordinates from a previous monitoring form into
the GPS unit. We can provide you with coordinates from previous years. Please see contact information
below if you have questions.
To enter coordinates written on the monitoring form into the GPS unit, first you need to chec the unit’s
settings and adjust them appropriately so they reflect the datum and format of the coordinates.
Make sure that you enter the reading according to the format of the coordinates that you want to find. The
three most common formats used are Decimal Degrees, Minutes/Seconds/Degrees, and UTM.
To enter the reading in the correct format, follow the instructions listed above under “Chec /Adjust Settings.” The
position format called Decimal Degrees is listed as “hddd.ddddd*” and uses the map datum called “NAD27
CONUS.” This means that when you set the position format to “hddd.ddddd*” you also need to make
sure that the map datum is “NAD27 CONUS.” The Minutes/Seconds/Degrees format is listed as
“hddd*mm’ss.s” and also uses the map datum “NAD27 CONUS,” and the UTM format is listed as
“UTM UPS” and uses the “NAD83” map datum.

EXAMPLE 1: The coordinates on the form are in UTM format; you need to make the settings in the unit
reflect the “UTM UPS” position format before you enter the coordinates. Go to MENU SETUP
UNITS according to the “Check Adjust Settings” instructions above. Highlight the “POSITION
FRMT” box and select “UTM UPS” as described in these instructions. The UTM format usually
requires a unique datum called “NAD83,” so highlight the “MAP DATUM” box and select “NAD83.”
• From the MENU screen choose “MARK.”
• Scroll down until the reading at the bottom is highlighted, press ENTER
• Highlight each digit in the coordinate number by scrolling with the UP DOWN button
• Press ENTER at the number you wish to change.
• Scroll up or down to the number you want to replace it with.
• Press ENTER to change the number.
• Scroll to the next number you want to change, repeat. Go through all the numbers, changing those you
wish to change.
• Once finished, scroll down to OK.
• Press ENTER when OK is highlighted. This will be your waypoint. Write down the title of the
waypoint you created (the number next to the flag), so you can go bac to it.
• When you are finished, simply get out of the Edit Location screen by pressing PAGE. You’ve created a
waypoint for your coordinates! Go onto the next section.
PLEASE NOTE: When entering UTM/UPS coordinates, the first two digits are “1” and “6”. Do not change this as
this represents “16”, the standard UTM zone for Illinois. The actual coordinates starts after the “ T ”.
Tracking Back to an Existing Waypoint (i.e. a waypoint you created):
• Press PAGE button to bring up MENU page
• Highlight WAYPOINTS and press ENTER (you are now in Waypoint Page)
• Select a tab (using UP DOWN) containing the number (or first letter) of the waypoint you are loo ing
for and press ENTER
• Select the waypoint that you are loo ing for and press ENTER
• Press UP DOWN button to select “GOTO” and press ENTER
• The Compass Page appears and you are now ready to be guided bac to your starting location. The # of
meters shown above is the distance to your waypoint.
The GPS Compass will start moving as you start moving toward your waypoint, but it does not function in the
same way as a conventional compass. It is not sensitive enough to detect which direction you are facing
initially so the arrow points in the appropriate cardinal direction but doesn’t change with respect to the direction
you are facing. For this reason, use an actual compass to tell you which direction is which before you begin.
EXAMPLE 2: Looking at the compass screen on the GPS unit, I can see that the arrow is pointing straight at
the “ ” on the screen with a distance of 6.66 m, indicating that I need to walk 6.66 m due orth to find
my plant. However, when I look at my own compass, I realize that I am facing South. Therefore, first I
adjust my direction by referring to my actual compass and turn to face orth. Then I refer to the GPS
compass screen.
Please do not change the setting of the GPS unit without following the directions above. If you are creating a
waypoint to be used to locate a population and the last reading is in UTM (used in 2003) we can help you
convert this into LAT/LONG so that you can enter a waypoint. Don’t fret, it’s not hard. With any questions
please contact the POC Research Assistant: call 847-835-6856 wee days during business hours.