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.
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
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
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….
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