NorthStar 6000i, Quickstart Manual And Reference Manual

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Reference section 2 — Position coordinates
Using DGPS or WAAS
Northstar 6000i
sented by circles; WAAS satellites are
represented by hexagons. The center of the satellite map represents
the center of the sky, and the outermost
ring is the horizon. The view is looking
down from above, with east to your right
and west to your left.
HDOP (Horizontal Dilution of Precision) is
a technical measure of the quality of your
position fix. It is calculated from the satel-
lites’ current positions. You’ll usually see
an invalid HDOP value displayed immedi-
ately after the
6000i is turned on, before
it’s ready to navigate. HDOP can range
from an ideal value of slightly less than
one, up to poor values of 10 or more. Any
value less than two indicates an excellent
satellite configuration.
Using DGPS or WAAS
When using the 6000i with standard
WAAS or an external radiobeacon DGPS
receiver, 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 or DGPS corrections remove
most of the errors caused by atmospheric
variations.
When the
WAAS
or
DGPS
indicator is
displayed at the right edge of the screen,
the
6000i is using this higher level of accu-
racy. When you require this additional
accuracy, be sure to check often to verify
that either the WAAS or DGPS indicator is
present.
For most applications, the built-in WAAS
receiver automatically supplies highly
accurate navigation data. DGPS correc-
tions are available only from a user-sup-
plied external DGPS receiver using the
SC-104 data format. No DGPS signal sta-
tus is displayed.
Satellite status screen