Garmin 210 - Manual (Page 59)

The navigation setup submenu is also used to select map datums and adjust
the built-in position and velocity filters. The GPSMAP system’s default map
datum is WGS 84, a worldwide map datum that’s suitable for use with most
government charts. You should only change the map datum if the charts you
are currently using specify a different map datum in the legend.
Using an incorrect map datum can seriously effect the accuracy of your GPSMAP
navigator. The map datum used on the GPSMAP should always match the datum of
the chart you are using. If no datum information is indicated on the charts you are
using, contact the chart manufacturer. Selecting and defining a user datum is rec­
ommended only for navigators with experience in global models and datums.
Map Datum (GPSMAP 210 and 220 only) provides a list of the available
map datums for use with the GPSMAP system. For a list of the available
GPSMAP datums, see Appendix F A ‘user’ datum option is also available to
allow entry of your own datum corrections. To define a user map datum:
1. Select the 'User' option from the datum list
2. Enter the datum values in each field. The values you enter will be based on their
difference from the WGS 84 datum.
3. Highlight the OK prompt and press to confirm the user datum.
Position Filter and Velocity Filter let you select the GPSMAP’s response
time to changes in track or ground speed. Four settings are available:
automatic, fast (3 seconds), medium (20 seconds), and slow (120 seconds).
Selecting a slower filter may be desirable in slow speed applications with
frequent ground track changes (sailing vessels, etc.). The automatic setting
is highly recommended for most applications.
lUJXILimMEW SECIION
Nmigalion Setup in
& Map Datums
10
Nnvigotion Setup
Position Format
Navigation Units
Depth Units
Heading
Map Datum
Position Fitter
Veiocity Fiiter
[Glossary
Southeast lose |L
Southwest Bose ^
Timbdlai 194S
Tokyo
Tristan Astro 1968
Uiti Levu 1916
Hake-Eniwetok *60
H6S 72
HGS 84
Zonderij
User
I
Use cursor to highlight choice, ENT to accept
auxiliary Options
Navigation Setup
Position Format
Havigatifi^Jjpi;^
Depth Ur
|dx
dy
Map Dati{ dz
Position
Velocity
hddd^mm.mmm'
NraitienI
Define User Map Dutum
0^,
0^
0^
0.00^
0.OOOOOOOOe-4
OK
1 Press ENT to enter data I
1------- Jl. il II Cancel 1
49