Chapter 5 - Understanding Position Coordinates
Page 5-4
961/962 Operations and Reference Manual, Rev. A
which affect accuracy. HDOP can range from an ideal value of
slightly less than one up to a poor value of 10 or more; any
value less than two indicates excellent performance.
Using DGPS to determine position
Using DGPS to
increase repeatable
accuracy
For a higher level of repeatable accuracy than basic GPS, you’ll
want to use differential GPS, or DGPS.
The 961XD/962XD includes an internal differential receiver,
and uses DGPS whenever signals are available. To use DGPS
with a 961X/962X, you must add an internal differential
receiver (call your authorized Northstar dealer for details).
With good DGPS corrections, your 961/962 should provide
better than four-meter accuracy (repeatable and absolute) 95
percent of the time, SOG readings accurate to 0.1 knot, and
COG measurements accurate to about 0.5 degree. For more
information about GPS, see “Using GPS to determine position”
starting on page 5-2.
NOTE:
When using DGPS as your navigation source, your position
coordinates may actually exceed the accuracy of some charts.
DGPS-in-use
indicator
The DGPS indicator appears as the word
DGPS
in the upper
left-hand corner of the
CHART
screen. When this indicator is
displayed, it means you’re using DGPS’s higher level of
accuracy for received data. When you require this additional
accuracy, check for the presence of this indicator, since its
absence means DGPS isn’t in use.
DGPS status screen
To display more information about received DGPS corrections,
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 DGPS differential
transmitter now in use. The lower half of the screen shows the
beacon’s name, and the transmitter’s frequency and baud rate.
The beacon name may sometimes be unknown, but the
system will work properly without it.
Summary of Contents for 961
Page 6: ...Page viii 961 962 Operations and Reference Manual Rev A ...
Page 8: ...Page x 961 962 Operations and Reference Manual Rev A ...
Page 14: ...Page xvi 961 962 Operations and Reference Manual Rev A ...
Page 92: ...Chapter 3 Using the Controls Page 3 34 961 962 Operations and Reference Manual Rev A ...
Page 160: ...Chapter 6 Creating Waypoints Page 6 18 961 962 Operations and Reference Manual Rev A ...
Page 176: ...Chapter 7 Creating Avoidance Points Page 7 16 961 962 Operations and Reference Manual Rev A ...
Page 202: ...Chapter 8 Creating Routes Page 8 26 961 962 Operations and Reference Manual Rev A ...
Page 380: ...Glossary Page G 8 961 962 Operations and Reference Manual Rev A ...
