Changing the Location Settings
To open the Location tab, press
MENU
twice to open the Main
Menu. Select
Setup
from the vertical tab list. Then select
Location
from the row of tabs along the top of the page.
Refer to page 117 of the “Appendix” for more information
about location formats and map datums. Also visit the National
Geospatial-Intelligence Agency (NGA) at http://www.nima.mil.
Changing the Location Format
When you change the
Location Format
, you change the coordinate
system in which a given position reading is displayed. The default
format is latitude and longitude in degrees, minutes, and thousandths
of a minute (hddd°mm.mmm).
You should only change the position format if you are using a map
or chart that specifies a different position format.
Selecting a Different Map Datum
Datums are used to describe geographic positions for surveying,
mapping, and navigation and are not actual maps built in the unit.
You should only change the datum if you are using a map or chart
that specifies a different datum. Changing the Map Datum causes
a status message to appear when you turn on the unit. The default
setting is WGS 84. The unit automatically chooses the best datum
depending upon your chosen position format.
WARNING:
Selecting the wrong map datum can result in
substantial position errors. When in doubt, use the default WGS
84 datum for best overall performance.
Selecting a Different Heading Reference
You can select from
Auto Mag Var
,
True
,
Grid,
and
User Mag
Var
.
Auto Mag Var
provides magnetic north heading references
that are automatically determined from your current position.
Changing the Heading causes a status message to appear when you
turn on the unit.
True
provides headings based upon a true north reference.
Grid
provides headings based on a grid north reference (and is used in
conjunction with the grid position formats).
User Mag Var
allows you to specify the magnetic variation at your
current position and provides magnetic north heading references
based upon the variation you enter. Enter the magnetic variation of
your current position in the
Magnetic Variation
field if you have
selected
User Mag Var
for the heading.
WARNING:
If
User Mag Var
is selected, the unit does not
automatically calculate and update the magnetic variation at
your present position. You must update the magnetic variation as
your position changes. Failure to update this setting may result
in substantial differences between the information displayed on
your unit and external references, such as a magnetic compass.
90
276C Plus Owner’s Manual
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