For an inexpensive introduction to GPS navigation, the Garmin eTrex is a good first choice. Its simple five-button design makes operation easy and despite it's small size and weight, it contains the same GPS receiver as more costly models. While the eTrex isn't made for navigating city streets, this 5.3 ounce unit is at home off road or on water.

There are two types of GPS receivers, those with electronic maps and those without. Those without maps are useful for undeveloped areas where instead of street signs and stores, you have natural reference points such as rivers and rock outcroppings. The only maps the Garmin eTrex has are those you create by entering groups of your own reference points, called "waypoints".

To enter your waypoints, you use the Map Page screen display of the eTrex. And each waypoint is identified with a name and symbol of your choosing. The scale of your map is displayed and is adjustable from 200 feet to 800 miles. Once you've created a destination, an overhead view of the route from your present location is shown, and you can start your trip. An animated figure represents you on the screen and walks as you move along the route. And as you progress, your actual path, your track, is shown instead of the route and is saved in memory. The receiver can store 10 of these tracks which you can use later for traveling in either direction.

A second type of display the Garmin eTrex has, is the Navigation Page. It shows an image of a compass with your direction and speed. If you've entered a destination, the direction, distance and time to it will also be shown. GPS receivers determine your direction by calculating the difference of locations as you move from one point to another. So the compass can only show what way you're headed when moving, not what way you're facing when standing still.

You can keep an eye on the GPS satellites the eTrex is tracking with the Satellite Page. It shows each satellite's position, signal strength, and an estimate of the position calculation accuracy. The 12-channel receiver has a error of less than 15 meters (about 49 feet) 95% of the time. It's also Differential GPS (DGPS) ready for even greater accuracy, but DGPS requires another receiver for getting the signals from a DGPS beacon transmitter.

The fourth main screen display of the Garmin eTrex, is the Menu Page. It directs you to the various functions for making and viewing waypoints, creating routes, saving and viewing track logs, and setting feature options.