Interfacing The 941X - NorthStar 941X Reference Manual

DGPS antenna
mounting
Interfacing the
941X
Page 112
The Northstar 8410 differential beacon receiver antenna should be
mounted as high as conveniently possible (but not at the highest point)
and as far away as possible from other antennas. If you have several pos-
sible antenna locations, you may evaluate each by operating the 941X
with the DGPS antenna temporarily mounted in each location. The best
location is one providing the lowest "NOISE" count (atmospheric im-
pulse noise generated by thunderstorms and other conditions) and high-
est Signal-to-Noise Ratio (SNR). Both values may be viewed using the
DGPS STATUS information screen accessed from the main GPS
POSITION screen, as seen on page 26.)
Another major concern, precipitation static (called "P-static"), must be
addressed when installing the antenna. P-static generally appears only
during rain or snow; consequently, it can be easily overlooked during in-
stallation.
Much like a loran antenna, the effects of P-static are minimized if the
beacon antenna is mounted so that it is not the highest metallic object on
the vessel. The highest metal object acts much like a lightning rod, at-
tracting tiny static discharges in the atmosphere. If the beacon receiver
antenna is the highest object, these discharges can totally override the
beacon signals and cause poor operation in bad weather. The optimum
antenna location is high and clear for fair-weather operation, but below
the top of a metal mast or other antenna for best foul-weather operation.
On sailing vessels, the ACU might be mounted on top of a low mast, or
on the stern rail if no other suitable location is available.
The 8410 beacon ACU can be mounted on a standard marine antenna
mount (one inch diameter, 14 threads per inch).
The 941X is easily interfaced to other equipment as described below.
NMEA 0183 is the most common interface data format used with 941X
installations. It is a widely-accepted standard of data transfer between
most all types of marine electronics today, enabling completely different
instruments to "speak" a common language.
9 — Installation and Interfacing 9 — Installation and Interfacing 9 — Installation and Interfacing 9 — Installation and Interfacing Rev. D