38
DATUM
Maps and charts are based on a survey of the area that’s covered by the
map or chart. These surveys are called “Datums”. Maps that are created
using different datums will show the same latitude/longitude in slightly
different locations.
All datums are named. The GPS system is based on the WGS-84 datum,
which covers the entire world. Other datums may also cover the entire
world, or just a small portion. By default, the Eagle Expedition shows your
position on the map using the WGS-84 datum. However, it can show your
position using one of 191 different datums.
To change the datum, first press the MENU key,
then highlight the “GPS Setup” label and press
the right arrow key. Now highlight the “Select Da-
tum” label. Finally, press the right arrow key again.
A screen similar to the one at right appears.
The WGS-84 label is highlighted. To change it, sim-
ply press the up or down arrow keys to highlight
the desired datum, then press the ENT key. This
selects the datum and erases the select datum
menu. To erase the menu without changing the
datum, simply press the EXIT key.
A list of the datums used by the Expedition is in the back of this manual.
The Expedition can use the military grid refer-
ence system (MGRS). It uses two grid lettering
schemes, which are referred to as standard and
alternate MGRS on the Expedition. Your posi-
tion and datum in use determines which one to
use. If you use the standard, and your position
is off significantly, then try using the alternate.
Press the up or down arrow keys to highlight the
desired position format. Press the EXIT key to
both select the format and erase the position for-
mat menu.
Содержание Expedition
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