Datum - Lowrance GlobalNav 200 Installation And Operation Instructions Manual

The GlobalNav 200 can use the military grid ref-
erence system (MGRS). It uses two grid letter-
ing schemes, which are referred to as standard
and alternate MGRS on the GlobalNav 200. Your
position and datum in use determines which one
to use. If you use the standard, and your posi-
tion is off significantly, then try using the alter-
nate.
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.

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 GlobalNav 200 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 GlobalNav 200 is in the back of this
manual.
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