For an introduction to GPS navigation, the Garmin GPS 12 is a simple, low-cost
answer. The slim handheld makes one-hand operation practical and the rugged
waterproof case is designed to put up with abuse. It even has a simulator
mode so you can develop you navigating skills without leaving home.
The guts of the Garmin GPS 12 is a 12 parallel-channel GPS receiver. It can
receive the signals from 12 GPS satellites at once, with at least 3 needed
to find your position and 4 or more, for elevation. The receiver lets you view the
navigation information with use of a simple menu system. If you select the
satellite page, you'll see three graphical images. One shows the location of GPS
satellites in your area. Another shows the battery power level. And the third
image is a bar chart of the signal strength for each satellite. There's also an
estimate of the overall error in the current position reading.
The position page of the GPS 12 gives you a snapshot of your current trip.
It shows the direction you're heading, your speed, altitude, latitude and
longitude, and the distance you've traveled. The compass page has a compass
image pointing to the next waypoint. The numerical bearing and distance along
with your current heading and speed, are also shown. The map page displays your
current position in relation to the waypoints in image and numbers. You control the
image scale and view with zoom and pan function keys.
Although the Garmin GPS 12 may be a basic model, it's still designed for
anywhere and anytime use. The 2.2" H x 1.5" W, adjustable-contrast LCD screen
is sharp when read in bright light. And with its built-in backlighting,
readings are just as easy in the dark.
You can store 500 waypoints with the GPS 12 and give them unique
names and symbols, plus adding comments. A group of waypoints forms a route and the
receiver has space for up to 20 routes with a maximum of 30 waypoints per route. Each of
the routes is capable of being followed starting from either end. There's also space to
save up to 9 proximity waypoints. These are usually hazardous areas you want to avoid.
You can select an alert distance and whenever you're within that distance from a
proximity waypoint, a warning message is displayed.
For those times when you don't plot your trip, the Garmin GPS 12 can do it
for you. The track log automatically records your path and stores the result.
So if you ever want to repeat the trip or backtrack the same way, you can simply
follow the track log route.
The normal error for the position calculated by the GPS 12 is less than 15
meters. To improve that to less than 5 meters, you can add a Differential GPS
(DGPS) receiver such as Garmin's GBR 21. The DGPS receiver gets unique GPS
correction data and transmits it to the GPS 12 to achieve the greater accuracy.
The Garmin GPS 12 has its power supplied by 4 AA batteries which will last up
to 24 hours of use. There's also an internal rechargeable lithium battery for
backup. For traveling in the car, an optional cigarette lighter adapter can be used
to supply power. For transferring navigation data to, or from a PC, there's an optional
serial interface cable available.