NorthStar 972, Installation Manual

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SECTION SIX: Interfacing the 972 system
972 Installation Manual, Rev. B Page 27
2. At the
Port 1 Setup
or
Port 2 Setup
screen, press the cursor pad to highlight the
NMEA
0183 talker id
option, then press
EDIT
.
3. Scroll through the choices using the cursor pad to make your selection, and press
ENTER
. The interfaced equipment will now receive the 0183 data in the correct
nav-source format.
Choosing the lat/lon precision
For more flexibility when communicating with a variety of other devices, you can set the precision
level of the 0183 position information output by the 972. The choice you make depends on the
equipment to which you’re outputting the NMEA data (for the number of digits of precision required
for that particular device, see the manufacturer’s instructions). You have three choices:
•
XX.XX’
(lat/lon precision to two decimal places (hundredths of minutes) or 60 feet)
•
XX.XXX ’
(lat/lon precision to three decimal places (thousandths of minutes) or 6 feet; this is
the factory setting)
•
XX.XXXx’
(lat/lon precision to four decimal places (ten-thousandths of minutes) or roughly
foot)
The 972 conforms to the NMEA version 2.00 standard, and is also compatible with version 1.50.
Electronic and pen plotting devices typically benefit the most from three and four decimal places of
precision. However, many older devices (and some current autopilots) designed to operate with the
original 0183 and other formats can only function with two-place precision.
Choosing the output rate
The default rate for standard NMEA 0183 output is two seconds. The 972 lets you use a one-second
update interval, a rate of 1 Hz, under limited circumstances, for NMEA and diagnostic data output.
Using the 1-Hz output option requires some thought when specifying NMEA 0183 (NMEA version
2.0). Because there isn’t enough time to transmit a large number of sentences within one second, you
must select for output only those that are needed. If you select more sentences than can be output in
one second, the 972 displays the following error message:
Sorry, can’t do that. too many sentences for 1 sec
interval
In this case, you must select fewer sentences.
If your application requires a longer update period, you can increase the span up to 999 seconds.
Choosing the waypoint identification (ID)
Many marine devices can display waypoint names if they’re output by the 972. At the
Port 1 Setup
or
Port 2 Setup
screen, highlight the
NMEA 0183 waypt id as
option, then press
EDIT
. Change the option
NOTE: Position information can be output and displayed to four
decimal places, but the ability to actually navigate with such
accuracy is limited by the accuracy of the Loran and GPS
systems. Therefore, choosing more decimal places doesn’t
necessarily increase navigating accuracy.