Basic GPS Navigation

What is GPS?

How to use GPS:
GPS Navigation

Overview of GPS devices from handhelds to watches:
GPS Comparison

GPS Products
Earthmate GPS
Garmin GPS
Magellan GPS
Navman GPS
Delorme Mapping
Garmin MapSource
Garmin Charting
Magellan MapSend

Using GPS to locate something or someone:
GPS Tracking

Increase the usefulness of your device with:
GPS Accessories
GPS Maps
GPS Software

GPS navigation involves a combination of technology and traditional location techniques. There are a variety of GPS receivers designed for use in the air, on the land, or on water. And how you navigate depends on your experience, the kind of trip you take, and the capabilities of your GPS unit.

How to Use GPS
Unless you're solely an gadget addict, you want a GPS unit as an aid to finding your way when making a trip. And if you want to use a specific GPS model, the owner's manual will tell you how. But there's a difference in knowing how to use GPS and how to make GPS useful.

If the only traveling we did was on highways, there would be little need for GPS. But if you're off road, flying, or on the water, a GPS device can provide directional information similar to road signs. In addition to a receiver, GPS navigation requires a map and probably a compass. GPS can provide your direction, but only when you're moving. Most GPS units are capable of displaying an electronic map and some also come with an electronic compass built in. If you need to know your altitude with precision, either get a separate altimeter or a barometric sensor as part of the GPS receiver. An advantage to having a separate map and compass is that they're still usable if the batteries in your GPS receiver die.

GPS Waypoints
Even GPS units that can't store regular electronic maps, let you create your own simple map by storing reference locations called, "waypoints". Each waypoint is identified by its location, along with a name and usually a symbol. For instance, you might be hiking and find a cave you'd like to explore at later time. The GPS receiver would determine your position and save the location with either a name you chose, or an automatically generated one, as a waypoint. Then later at a different location, the GPS unit could calculate the distance and direction from your present position to the cave waypoint. Most GPS receivers have enough memory to store anywhere from 100 to 1000 waypoints.

Just as a map isn't made of a single point, any GPS path you want to take probably needs more than one waypoint. A "route" is a group of waypoints that show a path you plan to take. And a "track" is the path of waypoints that you actually followed. Routes and tracks are stored by the GPS receiver with the waypoints and called a "track log".

How to Use a GPS Receiver
Each GPS device is operated somewhat differently, depending on the make and its functions. But GPS units do have certain operations in common. You need to set the receiver for the coordinate system and datum of the map you're using. You also need to "initialize" the receiver. Initialization is the GPS unit finding the local satellites and gathering location information. Since you could be starting anywhere in the world, it takes longer to acquire and process the satellite data than for subsequent position readings. Some receivers speed up the initialization process by having you input your approximate location and time. The receiver may also have to be initialized if it was moved several hundred miles since its last use.

Once a GPS receiver is initialized, it can display data about the satellites its tracking. The information includes which satellites are supplying signals, where they are and some estimate of position accuracy. Modern GPS units have 12 parallel channels which means they can simultaneously track up to 12 satellites. The more satellites used, the more accurate the positioning can be, but it's rare to have access to more than 10 at one time. The receiver will indicate your position and after you move to a new location, it can show your distance, direction and speed from your last position. After initialization you're ready to follow a map or your own route of waypoints to your destination.