Chapter 5 - Determining Your Position
957 Operator’s Manual, Rev. B Page 53
You’ll see your lat/lon on the GPS POSITION screen. If GPS
data isn’t available, you’ll see dashes instead of numbers.
You can display lat/lon as either degrees, minutes, and
seconds, or as degrees, minutes, and thousandths of minutes.
For instructions, see ”Changing your display settings” starting
on page 138.
The time of day, and today’s day and date are displayed at the
bottom of the screen. You can display time in a 12- or 24-hour
format, and you can designate a specific time zone. For
instructions, see ”Changing the time zone” starting on page
155.
SOG and COG readings are the result of instantaneous
measurements from the satellite signals. GPS speed is updated
every second. You can average these readings over a short
period of time, however, by changing the GPS speed averaging
value (see ”Changing your receiver settings” starting on page
146).
The 957 displays the name of the datum currently in use in
the center of the screen. The datum describes the reference of
the chart you’re currently using. Most new charts use the
NAD83 or WGS84 datum, which are nearly identical. Make
sure the datum that the 957 uses matches the datum shown
on the chart cartridge label. Using the wrong datum can
significantly reduce accuracy. For more information on
selecting the datum for your area, contact your authorized
Northstar dealer.
A brief status summary of the GPS receiver is displayed at the
top of the screen. Table 2 describes these various GPS status
messages.
Table 2: GPS status messages
Message Meaning
COMM FAIL
communication link or the GPS receiver has a problem
3D NAV
navigating with 4 or more satellites in 3-D mode
2D NAV
navigating with 3 satellites in 2-D mode
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