Garmin GPSMAP 168 Sounder - Manual (Page 85)

74
Reference
Main Menu:
Units Tab
The Units tab settings will affect how navigation information
is displayed on the GPSMAP 168 Sounder. When in doubt,
seek assistance.
If you are using a map or chart in conjunction with your
GPS, make sure the settings under the ‘Units’ tab of the
GPSMAP 168 Sounder match that of the map or chart. This
information should be displayed somewhere on the map or
chart. If the information is not present, contact the map
or chart maker to determine what position format, datum,
heading and units of measure are being used for the map
or chart.
,
Units Tab
Units Tab— defi nes the settings for Position Format, Map Datum, Heading, and the units of measure
for Distance, Speed, Elevation, Depth and Temperature.
The following settings are available:
• Position Format— is used to change the coordinate system in which a given position reading is
displayed. You should only change the position format if you are using a map or chart that specifi es a
different position format or wish to use a format you are familiar with. The default format is latitude
and longitude in degrees, minutes, and thousandths of a minute (hddd°mm.mmm’). The following
additional formats are available:
• hddd.ddddd°— latitude/longitude in decimal degrees only
• hddd°mm’ss.s”— latitude/longitude in degrees, minutes, seconds
• UTM/UPS— Universal Transverse Mercator / Universal Polar Stereographic grids
• British Grid • Dutch Grid • Finnish KKJ27 • German Grid
• Irish Grid • Maidenhead • MGRS • New Zealand
• Qatar Grid • RT 90 • Swedish Grid • Swiss Grid
• Taiwan Grid • Loran TD • User Grid • W Malayan RSO
For additional information on Loran TD setup, see pages 83-84.
• Map Datum— allows you to select the datum reference used to determine a given position. The
default setting is ‘WGS 84’. Datums are used to describe geographic positions for surveying,
mapping, and navigation and are not actual maps built in the unit. Although over 100 datums are
available (as listed on pages 88-89), you should only change the datum if you are using a map or
chart that specifi es a different datum.
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. ,
168 Manual Part 2.indd 74 11/18/2002, 3:37:59 PM