Global Positioning Global Positioning Systems Systems

in the Classroomin the Classroom

Today we use a constellation of artificial stars

provided by the

Global Positioning System.

3 clear signals will provide you with accurate 2 dimensional position.

A 4th will give reasonably accurate elevation information.

Sources of GPS ErrorsSources of GPS Errors Number of satellites visibleNumber of satellites visible — — The The

more satellites a GPS receiver can "see," the more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage interference, or sometimes even dense foliage can block signal reception, causing position errors can block signal reception, causing position errors or possibly no position reading at all. or possibly no position reading at all.

GPS units typically will not work indoors, GPS units typically will not work indoors, underwater or underground. underwater or underground.

Sources of GPS ErrorsSources of GPS Errors Satellite geometrySatellite geometry— This — This

refers to the relative position of the refers to the relative position of the satellites at any given time. satellites at any given time.

Poor geometry results when the Poor geometry results when the satellites are located in a line or in a satellites are located in a line or in a tight grouping.tight grouping.

Ideal satellite geometry exists when Ideal satellite geometry exists when the satellites are located at wide the satellites are located at wide angles relative to each other. angles relative to each other.

Three things to keep in mind….Three things to keep in mind….

Avoid buildings and trees…

They will weaken or block your signals

When trying to navigate…you must be moving to get accurate information…

?

Always remember that the GPS does not replace common sense.

It will ALWAYS SHOW YOU THE STRAIGHT LINE ALWAYS SHOW YOU THE STRAIGHT LINE ROUTEROUTE…

not the BEST ROUTEBEST ROUTE or the SAFEST ROUTESAFEST ROUTE!A

B

The Main PagesThe Main Pages

Every GPS displays its information on a Every GPS displays its information on a set of main pages. These pages set of main pages. These pages include:include:

Main Menu Page Main Menu Page Satellite PageSatellite Page

Map PageMap PageCompass PageCompass PagePosition PagePosition Page

MAIN MENU PAGESMAIN MENU PAGES

Garminetrex

Garmin12

Garminetrex Vista

GarminEtrex LEGEND

SATELLITE PAGESSATELLITE PAGES

GarminEtrex

Garmin12

Garminetrex Vista

Garmin60

•This is where we check if we have an adequate signal to use the GPS•The outer circle is the horizon, the inner circle is a 45o angle in the sky, and the dot in the centre is straight up.•The numbers in the circle correspond to the numbers in the bar diagram

GarminEtrex LEGEND

MAP PAGESMAP PAGES

Garminetrex

Garmin72

Garmin60

TRAKMAPS

•Some GPS units come with maps, others require a map to be uploaded to the unit.•Use the zoom option to change the scale of your map•Use the pan option to look at the off-screen parts of the map *quit or esc gets you back•Set your map to North Up or Track Up

GarminEtrex LEGEND

COMPASS PAGESCOMPASS PAGES

Garminetrex

Garmin12

Garmin60

Garmin60c

•This is the screen we use to navigate to a given waypoint•On newer units, (including the LEGEND) you can manipulate the

data fields to show what’s important to you•The arrow will show you the direction to travel (straight line)•The arrow is usually wrong if you are standing still –

you have to be moving!

GarminEtrex LEGEND

POSITION PAGESPOSITION PAGES

•On newer units, including the LEGEND your position is given right on the Satellite Page•The accuracy of these coordinates will depend on satellite reception•Position will likely be wrong if your map datum isn’t set properly

Garminetrex

Garmin12

Garminetrex Vista

Garmin60

GarminEtrex LEGEND

And finally….And finally….

Pick up your GPS!!Pick up your GPS!!

GARMIN ETREX LEGEND

GARMIN ETREX LEGEND

POWER BUTTON…press and hold to turn on.

GARMIN ETREX LEGEND

PAGE BUTTON…press to move through 5 screens.

GARMIN ETREX LEGEND

SCROLL BUTTONS…move up or down menus

GARMIN ETREX LEGEND

ENTER BUTTON…press to select an item.

GARMIN ETREX LEGEND

THUMB STICK….press to enter, scroll, hold to mark.

Press and hold the Press and hold the power button until power button until your GPS turns on…your GPS turns on…

then press the PAGE then press the PAGE button to get to the button to get to the

MAIN MENU.MAIN MENU.

Setup MenusSetup MenusThe Setup Menu can usually be found The Setup Menu can usually be found

on the Main Menu page.on the Main Menu page.

The setup menu is where you accessall the various settings which you needto know about to properly operate your

GPS.

Newer units have more options.

Lets Set our units…..(next slide)

GarminEtrex LEGEND

Setting your GPSSetting your GPS

Be sure to set the map datum to WGS Be sure to set the map datum to WGS 84 or 84 or the specific datum shown on the specific datum shown on the map you are usingthe map you are using

Set your Position Format (UTM or Set your Position Format (UTM or Lat/Long)Lat/Long)

Set the Units (metric or imperial)Set the Units (metric or imperial)

See the next slide for an example….See the next slide for an example….

Navigation SetupNavigation Setup

Legend

Position format:

Set to

UTM/UPS

Navigation SetupNavigation Setup

Legend

Units:

Set to

Metric

Navigate to the Navigate to the MAIN MENUMAIN MENU

LEGEND:

Go to FIND,Then WAYPOINTSThen NEAREST…

Navigate to the Navigate to the MAIN MENUMAIN MENU

LEGEND:

Go to MARK,

Then press the thumb stick.

Take both GPS units….Take both GPS units….

lets go outside and try lets go outside and try this…this…