If you want to create your own paths instead of following someone else's map, you should
like the Garmin eTrex Summit. In a rugged waterproof case weighing a mere 5.3 ounces,
it combines a GPS receiver, altimeter, and electronic compass. Whether your trips are
vertical or horizontal, on land or on the water, the Summit can guide you to your destination.
As good as GPS navigation is for calculating your position, it does have a
drawback when it comes to determining your direction. Only when you're moving from
one point to another, can GPS calculate your direction. Unlike a compass, it can't
tell you which way you're facing when standing still. But by including an electronic
compass, the Garmin eTrex Summit overcomes this problem.
When you want to find your direction, moving or still, you can check the Pointer
Page display of the eTrex Summit. It has an image of a compass showing your heading.
If you have a destination entered, the page also displays the time and distance to reach
it, its name, and the direction you need to go. The Pointer Page includes a data
field with optional navigation information you select, such as speed or elevation.
It's more difficult for GPS to accurately determine you're altitude compared to
calculating your horizontal position. Typical GPS elevation readings can have about twice
as much error as a position reading. To eliminate this problem, the Garmin eTrex Summit uses a
built-in altimeter to provide elevation readings within three meters, which is as
good or better than GPS position readings.
To check your altitude, you go to the Elevation Page display of the eTrex Summit.
It has your current elevation, your rate of ascent or descent, and a graph showing
the elevation changes over time or distance. A data field for information of your
choice can show such things as the air pressure, vertical speed, or maximum elevation.
The other main pages are the SkyView, Map, and Menu. The SkyView Page of
the Garmin eTrex Summit shows the GPS satellites being tracked, their overall signal strength,
and an accuracy estimate for position readings. The Map Page is the display for planning your routes.
The page has an animated figure that moves, as you do, along a route line. Also, as you and the figure move,
the route line is replaced by another line showing the actual path you took.
Your path is saved (with memory for 10) by the track log, so you can follow the same trail
again going in either direction. Also shown on the page is your destination's name and
symbol, and the direction you're headed. You create routes, calibrate the altimeter and
barometer, and set user options from the Menu Page. This page also has a image showing
the battery strength.
At the heart of the eTrex Summit is its 12-channel GPS receiver. Its position
calculations are accurate to within 15 meters and it provides updates every second.
The receiver is Differential GPS (DGPS) ready and if you have a DGPS beacon receiver,
you can reduce the position error to no more than 5 meters. Navigation data can
be transmitted by the receiver to marine instruments or other navigation equipment
which uses the National Marine Electronics Association (NMEA) protocol.
The display for the Garmin eTrex Summit is a high-contrast grayscale LCD measuring
1.1" W x 2.1" H. The contrast is adjustable and it's backlit with an adjustable shutoff
timer to conserve the batteries. Two AA batteries power the receiver for up to 16 hours.