Using Gps To Determine Position - NorthStar 961 Reference Manual

Chapter 5 - Understanding Position Coordinates

Using GPS to determine position

Lat/lon coordinates
SOG and COG
Loran-C TDs
GPS receiver status
summary
Page 5-2
The 961/962 uses a high-performance GPS receiver as its
primary source of position data. Calculated directly from the
received satellite data are your present position in lat/lon
coordinates, time of day and date, speed-over-ground (SOG)
and course-over-ground (COG), and an estimate of the
accuracy.
On the CHART screen INFO BARs, lat/lon is displayed as
degrees, minutes, and thousandths of minutes. To display this
data, press the INFO key several times. After pressing the first
INFO key, a second INFO key is displayed, letting you display
additional data on the second INFO BAR.
You can display SOG and COG in the INFO BAR on the CHART
screen, or on the 3-D STEER screen or numeric STEER screen.
To display SOG and COG on either the STEER or 3-D STEER
screens, press the STEER key once or twice.
SOG and COG readings result from ongoing measurements
derived from the satellite signals; GPS speed is updated every
second. You can set the 961/962 to display its SOG and COG
readings more smoothly by setting the GPS speed averaging
value up to 10 seconds. Increasing this averaging time,
however, may reduce overall reaction time. For details about
GPS speed averaging value, see "Changing GPS speed
averaging value" starting on page 14-5.
Loran-C TDs are also calculated from the GPS coordinates and
displayed on the CHART-screen INFO BARs. For details, see
"Viewing loran TDs" starting on page 5-9.
To display information about the GPS satellites, press the
STAR key until you reach the SERVICE MENU screen, then
press the GPS STATUS key. The GPS SATELLITE STATUS
screen appears, showing the status of the GPS receiver. This
screen also displays the status of the DPGS receiver, if
installed.
961/962 Operations and Reference Manual, Rev. A