Garmin Etrex User manual

Tristan Darwin Project
GPS Training
AGuide to Using the Garmin Etrex GPS

Tristan Darwin ProjectGPS Training - Garmin Etrex
Introduction
What is GPS and how does it work?
GPS stands for Global Positioning System.
AGPS device receives radio signals from
orbiting satellites which are owned and con-
trolled by the US military. Each satellite
‘knows’ its position to a very high degree of
accuracy and the receiver calcuates its posi-
tion on the ground by measuring the time dif-
ference it takes to receive the signal from
each satellite. It follows from this that in
order to work the receiver’s aerial needs a
clear view of the sky. With a handheld
device such as the Garmin Etrex the posi-
tion can’t be determined if its view of the sky
is obscured by obstacles such as cliffs or
dense tree cover, although clouds appear to
make little difference and it will usually work
on a car dashboard or inside the wheel-
house of a boat.
ENTER
Press this button
when you want to
choose an option or
to say ‘YES’
Pressing and holding
it down will tell the
unit to mark a way-
point at your present
position.
POWER button
ON/OFF
LIGHT ON/OFF
PAGE button.
Press to go back or
move to the next
screen,
or press when you want
to say ‘NO’
Using the Garmin Etrex GPS Receiver.
The Garmin Etrex is a 12 channel receiver
which means it can receive signals from 12
satellites at once. It runs on two AA batteries
which are said to last 22 hours; recharge-
able batteries are more economical but don’t
last as long, though you should get 10 to 12
hours from a newly charged set. The device
keeps all its data (waypoints and track logs)
even if it is switched off or the batteries are
removed. This unit is waterproof and has a
data connection port which greatly extends
its usefulness when used with a PC.
Button Layout
UP/DOWN
Press these
buttons to
move up and
down a menu
or to zoom in
and out

Tristan Darwin ProjectGPS Training - Garmin Etrex
SCREEN DISPLAYS
This GPS receiver has 4 different screens
which can be changed by using the PAGE
button.
1. SIGNAL STRENGTH SCREEN
This appears when you first switch the
device on. It takes a while to get a ‘fix’ on
each satellite. As more satellites are locked
on, the accuracy improves. (An ‘Advanced
Skyview’ can be seen as an alternative view
by pressing the ENTER button and choosing
this option - the display will show you exact-
ly where the satellites are in the sky.)
This is the screen you will see when you first switch on. The GPS
is ready to use when the signal display bar is full and the satellites
stop flashing and a link is shown to each of them.

Tristan Darwin ProjectGPS Training - Garmin Etrex
2. MAP SCREEN
While the Garmin Etrex GPS cannot display
maps of terrain or roads it does has a useful
map screen which shows the position of
waypoints and tracks you have made or
saved. The scale of the map is shown at the
bottom left; this can be changed using the
UP/DOWN buttons.
There are 2 different modes for this screen -
North Up or Head Up.
In North Up mode your position is shown as
an arrow head which points in the direction
you are going. This screen is most useful
when you are making a new track. North is
towards the top of the screen (whether this
is True or Magnetic depends on how you’ve
set it up - details of this are given later).
In Head Up mode your position is shown as
a little man who walks as you move. Your
position is where his head is and the map
always shows what’s ahead. of you; An
arrow shows where North is.. This screen is
most useful when you are retracing your
steps, following a recorded track or aim-
ing for a waypoint.
If there aren’t enough satellites in view
and the unit isn’t ‘ready to navigate’ your
postion marker is replaced by a flashing
question mark.
Waypoints in range are displayed on the
screen with their name. As you move
along, the position marker leaves a trail
behind it on the screen (a bit like a snail
leaving a silvery trail) and this can be
very useful for retracing your steps or fol-
lowing a route or track you’ve recorded
before.
NOTE - This GPS unit can only tell which
way is North when it is moving, once you
stop it can’t determine which direction
you’re facing. More sophisticated units
have a built-in compass which works
even when stationary.
Map Screen - North Up Map Screen - Head Up

Tristan Darwin ProjectGPS Training - Garmin Etrex
3. COMPASS SCREEN
The main part of this screen shows a repre-
sentation of a compass. In normal use this
will act like a compass showing your direc-
tion of travel (see note on previous page
about its limitations). When used to navigate
to a particular waypoint or to follow a route
or track, an arrow will show you which way
you should be going. When used like this it
will also tell you how far it is to go and how
long it will take to get there at your current
speed.
There is a lot of additional information avail-
able at the foot of this screen. This includes:
Location, Current Speed, Max Speed,
Heading, Trip Time, Distance Covered,
Sunrise, Sunset etc. You can cycle through
these using the UP/DOWN buttons.
The ENTER button shows a menu
where you can reset the trip time
and max speed as well as stop
navigating to a waypoint or route
(STOP NAVIGATION).
Pressing the UP/DOWN but -
tons will change which informa -
tion is shown at the foot of the
screen eg Location and Speed
as shown here
Here the arrow shows that you
need to travel South to get to
waypoint ‘G1330A’ which is
currently 4.88 miles away as
the crow flies.
No time is shown for how long
it will take to get there ( ‘--.-- TO
GO’) because the unit isn’t
moving, ie our current speed is
0 mph.
Press the ENTER button to
reset max speed or to stop nav -
igating to Waypoint ‘G1330A’.

Tristan Darwin ProjectGPS Training - Garmin Etrex
4. MENU SCREEN
This is where you can edit or delete the stored data.
The options are as follows:
MARK
Use to mark a waypoint. You’ll probably use this
when you want to mark a point you want to go to -
if you’re already there its much easier just to press
and hold down the ENTER button.
Screen showing list of stored
waypoints
If you select a
waypoint from
the list you get
this screen
where you can
see details of the
waypoint and
edit it.
WAYPOINTS
Here you will find all the stored waypoints listed in
alphabetical order.This unit will store up to 500
waypoints. Here you can view or delete them, or
edit their name, position or symbol. To put in the
position of a waypoint that you’ve determined from
a map or chart, use the UP/DOWN buttons to high-
light the position shown at the bottom of the screen
and press ENTER to change it (this sort of thing is
much easier to do on a computer). Note that while
it does show altitude this is not always accurate -
there is no altimeter built into this model.

Tristan Darwin ProjectGPS Training - Garmin Etrex
ROUTE This unit will store one route
which is simply a list of waypoints in the
order in which you want to visit them. This is
where you choose which waypoints to
include in your route.
TRACKS This is where you can see
details of the track you have recorded as
you move along, called a Track Log. The
track currently being made will slowly fill up
the unit’s memory; once the memory is full it
will continue to record the track but will begin
to delete the track recorded right at the start.
You can check how full the memory is at the
top of the screen.
You can save up to 10 track logs you have
made. The unit will ask what time you want
the track record to start; if you cleared the
active track at the start of the trip you can
just tell it to save the entire log. It will save it
with a name using today’s date, but you can
edit this at any time. Asaved track can be
used to TRACBACK ie follow your track
back to the start.
Select the waypoint name and you
get the option to edit its name using
the UP/DOWN keys. Confirm with
the ENTER key. (you can’t use the
same name for two different way -
points)

Tristan Darwin ProjectGPS Training - Garmin Etrex
SETUP
This is where you set up the unit. Here you can choose
which position format to use eg degrees.decimal degrees or
degrees minutes seconds etc.; the units to use eg statute
miles / nautical miles / metric; local timezone; display con-
trast; interface and system. You can easily swap between
settings eg a waypoint recorded in ddd.ddddd can also be
shown in ddd.mm.ss,etc.
The Darwin Project in Tristan
uses GMT timezone, WGS84
map projection, ddd.ddddd
position format (not really the
most convenient but its
required for a software pack-
age we use called MAPINFO)
and True North. T h e
‘Interface’ is set to ‘GARMIN’
(required for computer con-
nection) and the ‘System’ set-
ting is set to ‘Battery Save’
which seems to put the unit on
hold when its not moving thus
saving the batteries. Whether
you use miles or Km is a mat-
ter of personal preference.
The DISPLAY screen
lets you adjust the
screen contrast and
set how long the light
will stay on after the
POWER button is
pressed
This is also where you
can check the battery
status