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8.12 MAP DATUM SELECTION
Select the desired map datum
reference from the Map Datum Page.
You may choose from 102 pre-defined
map datums, or you may define your
own. If the sectional/chart you are
using specifies a reference datum,
select that datum on your GPS 95. If
the sectional/chart does not specify a
reference datum, you may select each datum applicable to your region until
you find the datum that provides the best positioning at a known point. NOTE:
The GPS 95 is shipped from the factory with the WGS 84 datum selected.
To change the pre-defined datum...
· Highlight the “Change?” field and press ENT.
· With the arrow keys, find the desired datum and highlight it.
· Press ENT. The new datum is selected.
The user-defined datum option allows
you to custom-tailor a datum reference
from which all position coordinates are
calculated. All entries are defined as
differences from the WGS 84 standard
datum. (CAUTION: Selection and
use of the user datum function is for
individuals experienced in the use of
map datums. If the pre-defined map
datums do not correspond to the chart you are using and you are unsure of
the correct entries required to correspond to that chart, contact the chart
manufacturer. Incorrect entries for a user-defined datum may result in
substantial position errors.)
To define a user datum...
· Place the cursor over the cyclic field on line one.
· Press CLR to select “User-defined”.
· Enter the 5 parameters of the user map datum. The sign of the
parameters should follow the convention: WGS 84 - local geodetic
system.
