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 walk through. Review these instructions
prior to going out in the field. Please take readings for annual populations, new populations, and populations
that have dramatically changed in size. We suggest taking 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 quickly. POC uses rechargeable batteries.)
•
You will get a message,
“Wait…tracking satellites”
(A good signal needs 4 satellites—takes 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 track satellites in a nearby open area first, then
bring unit (with the power still on) back 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, keep the unit
on and wait a few minutes for the error to reduce as you walk 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 º
W 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 know 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.
