NOVA SCOTIA GROUND SEARCH
AND RESCUE ASSOCIATION
SEARCHER MODULE 5
GPS COURSE
FULL DAY
NOTE ON GPS USE
GPS enhances, not replaces
traditional map and compass navigation.
NOTE ON CLASS
EXAMPLES
Some classroom examples are based on the Garmin
GPSMAP60.
As this course cannot cover all GPS units, members
should consult their GPS owner’s manuals for the class
exercises or ask one of the instructors for assistance.
HOW GSAR USES GPS
Determining a team’s location in the
field
Creating a record of a team’s travels
Assist in navigating to specified
locations
Data recorded is used during a search
by the Overhead Team and for
debriefing, training, etc
GPS INTRODUCTION
The Global Positioning System or GPS was
originally developed by the US Department of
Defense as a 24 hr a day, 365 days a year global
navigation system for the military. The system
utilizes 24 satellites that orbit the Earth in a
configuration that virtually guarantees that at
least four satellites are in view of any place on
Earth at any time.
The system requires a minimum of 3 satellites
to calculate a position (2D Fix).
4 satellites are required to calculate both
position and elevation (3D Fix)
In order to receive signals, the unit must have
an unobstructed view of the satellites.
Signals can be blocked by trees, buildings and
even your body, however, they can travel
through glass/plastic.
Always ensure that the antennae has a clear
view.
GPS is the most accurate method of electronic
navigation available to the general public.
However, the GPS is only a navigational aid. It
is meant to enhance, not replace, traditional
map and compass navigation.
You should always carry a map and compass
and spare batteries.
GRID REFERENCE
SYSTEMS
Topographic maps have two types of grid
reference systems:
Geographic (Latitude and Longitude)
Universal Transverse Mercator (UTM)
GSAR in Nova Scotia uses UTM
UTM
The UTM grid is a ground based system.
The grid consists of a system lines forming squares
over the entire map.
The area of a square depends on the map’s scale.
The entire UTM grid system is comprised of 100 x 100
kilometre blocks. The grid lines are numbered and
printed along the borders of the map and at intervals on
the map area.
Using the UTM system, any point can be designated to
an increment of 1 metre.
A grid map reference is given by a zone and
pair of numbers (an Easting and a Northing).
The zone for mainland Nova Scotia is 20 and
does not have to be given.
A UTM map reference looks like: 476659E
4942592N
The Easting has 6 digits and the Northing has 7.
The Easting is always read first. Using a metric
ruler and a 1:10000 map, you can determine the
location of an object within 10 meters or better.
Example of a 1:10000 scale map
UTM GRID REFERENCE
EXERCISE
Using the provided map, determine the grid references for the
following:
A)
B)
C)
D)
SCHOOL.
COMMAND.
CAMP.
PLS.
UTM GRID REFERENCE
EXERCISE
ANSWERS
A) SCHOOL:
000000 E 0000000 N
B) COMMAND:
000000 E 0000000 N
C) CAMP:
000000 E 0000000 N
D) PLS:
000000 E 0000000 N
DATUMS
Map grids are based on a series of accurately surveyed
points called datums to ensure that the grids are
consistent on all maps.
Newer Nova Scotia maps use the NAD83 datum.
Using the wrong datum can result in grid references
being off by hundreds of meters.
When entering grid references into a GPS, the user
must ensure the datum of the GPS is set to the datum
of the map.
A map’s datum is located on its margin.
Nova Scotia GSAR teams use the NAD83 datum.
BASIC GPS FEATURES
Most GPS receivers have similar graphic
displays, including:
Satellite/status page that displays signal strength
and location
Navigation page that displays a compass face and
navigation information
Map/plotter page that displays position,
waypoints, tracks and maybe maps
Menu page for adjusting various GPS settings
Most GPS receivers have similar function
buttons, including:
Light, zoom, power, page, menu, set waypoint,
find waypoint, enter and select.
Some units like the Garmin eTrex Legend have
a “thumb stick” that acts similar to the mouse
on a computer.
Example of a GPS’ features and controls
Example of a GPS’ display pages
VIEWING GPS PAGES EXERCISE
Turn on the GPS. Press its Page button repeatedly to cycle
through the available pages. Take specific note of the
Satellite, Navigation/Compass and Map pages.
NOTE: If needed, consult your GPS owner’s manual or
ask an instructor how to view your unit’s pages.
GPS SETUP
To ensure accurate data and uniform use, all
GPS receivers used on a search must be
configured to the team standard.
Members who demonstrate that they can
configure their personal GPS receiver to the
NSGSARA standard are welcome to use the
unit on a search.
NSGSARA GPS STANDARD
GPS units must be configured to the standard
prior to a search. The basic standard is as
follows:
If power < 50%, replace batteries. Issue spare set.
Clear all waypoints and tracks.
Set datum to “NAD83”.
Set position format to: “UTM”
Ensure bearing and heading are displayed and are
in degrees magnetic.
It is beyond the scope of this course to go over
the detailed configuration of these units. It is a
searcher’s responsibility to know how to
configure their GPS unit to the NSGSARA
standard.
When on a search the standard settings are not
to be altered.
DETERMINING LOCATION
In order for the unit to determine your location,
it must receive signals from orbiting GPS
satellites.
To get these signals, the unit has to have a good
view of the sky. Getting a signal can take a
minute or so.
Most GPS units will display a message similiar
to “Acquiring satellites” until a signal is
obtained.
Satellite Page
Trip Computer Page
Example of a GPS showing current location
REPORTING LOCATION
EXERCISE
If your classroom is equipped with a re-radiating antenna your GPS
can receive signals without going outside. To get a signal, ensure
your unit’s antenna faces the re-radiating internal antenna.
If you must go outside for this example, give the antenna a clear
view of the sky.
1.
2.
3.
Turn your unit off then on again and try to get a signal.
Once the unit gets a satellite signal, it has determined your
location. Find the location display on your GPS unit.
When asked, report your location.
REPORTING LOCATION
EXERCISE
ANSWER
PRESENT LOCATION: 000000 E 0000000 N
WAYPOINTS
A GPS has the ability to create a database of
locations called “waypoints”.
A main function of a GPS is navigating to a
stored waypoint.
A GPS tends to name waypoints with numbers.
The user can re-name waypoints. For example,
the waypoint “002” can be re-named to
“Camp”.
1.
Press
the
Mark
button.
2.
3.
Select
waypoint
name.
Edit
waypoint
name.
4.
Click
OK to
save the
waypoint.
Example of saving current position as a waypoint
SAVING YOUR POSITION
EXERCISE
Save the location of the classroom as a waypoint. Name
the waypoint “CLASS”.
What are the coordinates of the classroom?
NOTE: If needed, consult your GPS owner’s manual or
ask an instructor how to complete this exercise.
SAVING YOUR POSITION
EXERCISE
ANSWER
CLASS: 000000 E 000000 N
SAVING A GIVEN
COORDINATE
A waypoint can be created from a set of UTM
coordinates.
The datum set on the GPS must match the
datum of the given coordinates.
This feature has many uses during a search
including:
Ensuring a team is dropped off at the right
location.
Marking location of a clue.
Determining the location of a team in the field.
1.
2.
3.
Press
mark
button.
Select
coordinate.
Edit
coordinate.
4.
5.
6.
Select
waypoint
name.
Edit
waypoint
name.
Click
OK to
save
waypoint.
Example of saving a coordinate as a waypoint
SAVING COORDINATES
EXERCISE
Using the coordinates you determined for the CAMP,
SCHOOL, COMMAND and PLS from the previous
mapping exercise, save them as waypoints. Name them
appropriately.
NOTE: If needed, consult your GPS owner’s manual or
ask an instructor how to complete this exercise.
PROJECTING A WAYPOINT
Another method of saving a waypoint is
“projecting”. A projected waypoint is one that is
created based on the distance and bearing from
another waypoint.
Projecting waypoints can be very useful during
a search. For example:
A team tasked to go to a clearing 800 meters
away on a bearing of 250 degrees magnetic,can
use a GPS to create (project) a waypoint for the
clearing based on the given distance and bearing.
1.
Select or
mark
waypoint.
Press
Menu,
choose
Project
Waypoint.
4.
Name
projected
waypoint.
2.
3.
Enter
distance.
Enter
magnetic
bearing.
5.
Click OK
to save
original
waypoint
if Mark
pressed
in #1.
Example of projecting a waypoint
PROJECTING A WAYPOINT
EXERCISE
Project a waypoint for a location that is 2.12 km away from
the classroom on a bearing of 300 degrees magnetic.
What is the grid reference for the projected waypoint?
NOTE: If needed, consult your GPS owner’s manual or
ask an instructor how to complete this exercise.
PROJECTING A WAYPOINT
EXERCISE
ANSWER
PROJECTED WAYPOINT: 000000 E 0000000 N
WAYPOINT NAVIGATION
One of the most important functions of a GPS is
its ability to guide a user to a stored waypoint.
GPS receivers have several pages that are useful
for waypoint navigation including:
The map/plotter page allows the user to see where
they are in relation to their destination waypoint.
The navigation page uses a compass face to
display bearing, heading and distance to the
waypoint.
The direction page displays driving directions (if
GPS has an “autorouting” capability).
A GPS can generate a variety of useful
navigational information including:
Distance and bearing to a waypoint
ETA to waypoint
User’s heading
Distance traveled
Map of the area (if equipped)
Distance user has drifted off original bearing
GPS margin of error
Rate of travel
RECOMMENDED NAVIGATION
METHOD
NSGSARA recommends using a GPS in conjunction
with a magnetic compass to navigate to a waypoint:
Read the bearing to the waypoint from the GPS and set it
on the compass.
Note the distance to the waypoint and set off following
the compass bearing.
Occasionally check the bearing and distance to the
waypoint on the GPS. If you have drifted, dial the new
bearing into the compass and set off again.
Continue in this manner until arriving at the waypoint.
1.
Press
FIND,
select
Waypoints,
press
ENTR.
4.
Select
Off
Road
and
press
ENTR.
2.
Select
waypoint
and press
ENTR.
3.
Select
Go To
and
press
ENTR.
Note the
navigation
information
displayed by the
Compass and
Map pages on the
left.
Example of navigating to a waypoint
GPS HEADINGS
Most GPS receivers only give accurate heading
data when the user is moving.
When moving slowly, or stopped, unless
equipped with an electronic compass, a GPS
doesn’t know in which direction the user is
facing.
It’s for this reason that NSGSARA strongly
recommends the use of a magnetic compass in
conjunction with a GPS.
MARGINS OF ERROR
It is important to note that GPS data includes a
margin of error.
A reported position may be off by 5, 10 or more
meters.
Most GPS units will indicate the margin of
error. The margin of error usually is displayed
on the same page as the current location.
ELECTRONIC COMPASSES
Some GPS units include an electronic compass.
An electronic compass displays accurate
heading information regardless of whether user
is moving or stopped.
Great care has to be taken using an electronic
compass. Note the following:
Compass only works if held level.
Compass must be frequently calibrated.
Compass is useless without batteries.
WAYPOINT NAVIGATION EXERCISE
Select the SCHOOL waypoint and instruct the GPS to navigate to it.
From the navigation data generated, determine how far the
SCHOOL is from the classroom. What is the bearing from the
classroom to the SCHOOL? What is the margin of error?
If time allows, try navigating to COMMAND, the CAMP and
PLS.
NOTE: If needed, consult your GPS owner’s manual or ask an
instructor how to complete this exercise.
WAYPOINT NAVIGATION
EXERCISE
ANSWERS
A) CLASS to SCHOOL :
0.0 km, 000° mag.
B) HALL to COMMAND:
0.0 km, 000° mag.
C) CLASS to CAMP:
0.0 km, 000° mag.
D) CLASS to PLS:
0.0 km, 000° mag.
MAPPING SOFTWARE
Mapping software is often used in conjunction
with a GPS receiver.
With mapping software, one can:
Plan routes
View/edit GPS tracks
Measure distances and bearings
Load maps onto a GPS
Create/edit waypoints
Up and download from a GPS
Search data displayed using Ozi Explorer
UPDATING GPS FIRMWARE
A GPS receiver has an operating system
(firmware) just like a desktop computer.
GPS manufacturers from time to time update
the fireware to fix problems and add new
features.
Check your GPS owner’s manual to see if your
unit supports firmware updating.
END OF
CLASSROOM SESSION
It’s time to get outside and practice!!