GPS RECEIVER OPERATING INSTRUCTIONS
[These instructions are for use mainly with the Magellan Meridian Series of GPS receivers. Instructions in parenthesis are intended to aid in the use of other types of receivers that may be available during the demonstration.]
How the receiver works for you and how to control it.
The way the receiver interface works is by displaying different screens.
You can go from screen to screen by pressing the ESC key on the Magellan receivers (the PAGE key on the Garmin receivers.)
Waypoints
A very important use of the GPS receiver is to guide you back to places you have previously visited, or to places with known coordinates. Such points, whether you mark them as they are visited or enter them into the receiver with coordinate values or map locations, are known as waypoints.
TODAY’S ACTIVITY
In order to become familiar with the basic operation of the receiver we can play a little game. One member of the group will save a waypoint (the location of some prominent object) in the receiver. This is done out of sight of the other group members. Then someone else in the group will use the receiver to navigate in the attempt to discover the object.
Turn the receiver on: Press the PWR button with the red icon on it (or just the red button.)
You will be prompted to push some button(s) in order to acknowledge the disclaimers on the view screen. If you agree to the terms, press the required key(s).
Allow the receiver to acquire the satellites and fix your initial position. This may take a minute or two. The receiver requires an unobstructed view of a minimum number of satellites.
It is very easy enter a waypoint. All you have to do is hold down the GOTO key for a second or two (if there is no GOTO key, hold down the ENTER key.) After a second or two a screen will come up asking you to name the point. You use the ROCKER key (the big black key in the center) to scroll move around on this screen. To choose letters or numbers use the ROCKER key and the ENTER key When you are done naming the point scroll to the area that says save and push the ENTER key.
Now, when you give the receiver to the other group members they will try to find the point that you marked. To do this they use the same keys (GOTO or NAV) but this time don't hold the key down, just press it and let go. You then scroll to the point name and push the ENTER key. There are several screens you can use while trying to find the point again. The main one has the compass face on it along with an arrow pointing in the direction of the destination point. There are also some small areas that tell you things like your speed and the distance to the destination point. You will be shown more about how to operate the receivers when we are all outside. Refer to the information given below for further instructions regarding the use of the receiver to navigate.
NOTE: The GPS receiver does not work like a compass. Even though one of the screens shows a compass face, the GPS receiver cannot perform as a regular compass does. This means that you cannot rotate in place and use the GPS receiver’s compass face to determine your orientation. Of course with a regular compass you are able to do this. A compass uses a magnetized needle and the Earth’s magnetic field to indicate direction. It so happens that the Earth’s north magnetic pole lies close to the geographic North Pole. The difference between the two poles is known as declination. Declination can be fairly large (over 20 degrees at the edges of the continental U.S.) and changes with time. Therefore, precise navigation with a compass can be tricky.
A GPS receiver determines direction by using the coordinate values of different positions. A GPS receiver can indicate direction only if it has more than one position to work with. Therefore, it cannot indicate direction if you stand in place and rotate. If you wish to know in what direction an object lies, simply walk towards the object and soon the GPS receiver will indicate the correct direction. Furthermore, this direction does not suffer from the troubles associated with declination, as does the regular compass.