NOVA SCOTIA GROUND SEARCH AND RESCUE ASSOCIATION

SEARCHER MODULE 5

GPS COURSEGPS COURSE

FULL DAY FULL DAY

NOTE ON GPS USE

GPS GPS enhancesenhances, not , not replacesreplaces traditional map andtraditional map and comcom--pass navigation.pass navigation.

NOTE ON CLASS EXAMPLES

Some classroom examples are based on the Garmin Some classroom examples are based on the Garmin GPSMAP60. GPSMAP60.

As this course cannot cover all GPS units, members As this course cannot cover all GPS units, members should consult their GPS owner’s manuals for the class should consult their GPS owner’s manuals for the class exercises or ask one of the instructors for assistance.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 travelsAssist in navigating to specified locationsData 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 4942592NThe 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 thefollowing:

A) SCHOOL.B) COMMAND.C) CAMP.D) 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 EXERCISETurn 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.

Example of a GPS showing current location

Satellite Page Trip Computer Page

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. Turn your unit off then on again and try to get a signal.2. Once the unit gets a satellite signal, it has determined your location. Find the location display on your GPS unit. 3. 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”.

Example of saving current position as a waypoint

1. 2.

4.

3.Press the Mark button.

Select way-point name.

Edit way-point name.

Click OK to save the way-point.

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.

Example of saving a coordinate as a waypoint

1. 2.

4.

3.

5. 6.

Press mark button.

Select coord-inate.

Edit coord-inate.

Select way-point name.

Editway-pointname.

Click OK tosaveway-point.

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.

Example of projecting a waypoint

1. 2.

4.

3.

5.

Select or mark way-point. Press Menu, choose Project Way-

point.

Enter distance.

Enter mag-netic bearing.

Name pro-jected way-point.

Click OK to save original waypoint if Mark pressed in #1.

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.

Example of navigating to a waypoint

1. 2.

4.

3.Select waypoint and press ENTR.

Select Go To and press ENTR.

Select Off Road and press ENTR.

Press FIND, select Way-points, press ENTR.

Note the navigation information displayed by the Compass and Map pages on the left.

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 andPLS.

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!!