Displaying Position, Cog, And Speed; Using Gps - NorthStar 972 Quickstart Manual And Reference Manual

Displaying position, COG, and speed

Using GPS

When you're using
WAAS signals, your
position coordinates,
as calculated by the
972, may actually
exceed the accuracy
of some charts.
Reference section 3 — Position coordinates
46

Displaying position, COG, and speed

The 972 uses a high-performance GPS
receiver as its source of position data, with
accuracy enhanced by the WAAS satellite
system. The 972 can display position as
Position, Course Over Ground (COG),
Speed Over Ground (SOG) as well as time
and date are all calculated from the
received satellite data. To display this
position information numerically, press the
key.
POSITION
GPS position screen
You'll see your lat/lon coordinates on the
screen.
GPS Position
latitude/longitude coordinates, or as
loran-C coordinates calculated from the
GPS data.
If GPS data isn't available, you'll see dashes
instead of numbers.
The time of day, and today's day and date
are displayed at the bottom of the screen.
The name of the datum currently in use is
displayed in the center of the screen. Each
marine chart uses a coordinate system
described by its datum. Most new charts
use the WGS-84 datum.
When using the 972 with WAAS correc-
tions, you'll usually see position
measurements accurate to about one to
three meters, speed measurements
accurate to about 0.1 knot, and COG
measurements accurate to about 0.5
degree. WAAS corrections remove most of
the errors caused by atmospheric
variations.
When the WAAS indicator is displayed at
the right edge of the screen, the 972 is
using this higher level of accuracy. When
you require this additional accuracy, be
Northstar 972