"RayD" wrote in :

This looks like a useful accessory, especially on those long offshore
night watches. Anyone have any experience using it w/Nobeltec?
http://www.milltechmarine.com/SR161.htm




We've just upgraded Lionheart's AIS receiving from the self-contained
little LCD display with no chart to using the SR161 to The Cap'n, our nav
software of choice. As the SR161 only outputs 38,800 baud serial data,
incompatible with the NMEA 0183 network's 4800 baud data, you have two
choices in how to hook it up to your system.

Choice one is to send Meindert a few hundred dollars for his NMEA
multiplexer that has a 38,800 baud input. The multiplexer buffers the
data and feeds it into the data stream as AIS statements (which, by the
way, are NOT NMEA statements) for your various AIS-compatible units to
dissolve. This may become a problem in areas of intense shipping where
there may be too many ships transmitting high speed data for the measily
NMEA 4800 baud data stream to process.

Choice two is $8 at Radio Shack! Radio Shack (or any computer store) has
a RS-232C serial to USB converter cable whos electronics powers itself
from the computer's USB port. The cable comes with a software driver CD
that self-installs before connecting the cable. Once installed, each
time you plug in the cable, a new COM4 serial port shows up that your nav
software can access. So, I have the NMEA network coming in at 4800 baud
to COM1, the only 9-pin serial port on the boat's laptop. The SR161's
serial output plugs directly into the Radio Shack's $8 Serial-to-USB
adapter cable, which its driver fools the computer OS into thinking is
another RS-232C serial port running at 38,800 8-N-1 no flow control
serial port that intense shipping will not overrun with AIS data. The
Captain's latest version 8.3 digests the AIS higher speed data stream and
sends it out over the 4800 baud NMEA data network to the other chart
plotters....but only those plotters who have firmware upgrades that
include support for AIS data plotting....the new ones. We only need it
on the main computer at the nav station easily seen from the helm.

Sorry I don't know if Nobeltec's software handles it like this, but I
suspect it would. The Captain easily reads both ports.

From a Metz Manta 6, 1/2 wave VHF whip, atop our 42' mizzen in the middle
of all those masts at Charleston City Marina, I'm seeing ship
transmissions with the SR161 out about 20-25 miles. I suspect it will go
further away from the intense paging system interference, once we get it
to seaward. The receiver in it is very sensitive to these little 12 watt
transmitters, even in this noise.

Yes, AIS is very useful for navigation, indeed. Just having that ship's
MMSI, name and callsign over there on the horizon, when your boat starts
flooding, could save lives.....

I want us to have a transponder....I'm working on that goal. Lionheart
should be on all those displays by next year....(c;

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.