My NMEA configuration, updated with AIS

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Summer 2008 --

Last year I got everything integrated, but I had one HUGE problem.
According to the Fugawi software, my position would skip hemispheres every few minutes,
and I'd end up with a track that looks like this:

The Nexus NX2 Server is no longer the core for connections. The Brookhouse multiplexer has that function.
The NX2 is still critical, though, as it performs a lot of data manipulation on all the NMEA inputs and Nexus instruments, and controls all the displays in the cockpit, companionway and nav station.

The Brookhouse mux can accept 38400 baud AIS input from the Milltech reciever, but I decided not to integrate it. The only thing I have that can process AIS is the Fugawi software on the laptop, so there's no reason to clog the network with AIS information.


Because of the Fugawi / NX2 integration hassle, I've been constantly fussing around with NMEA configurations.
Here's what they were, but the next time I'm at the boat I need to update these spreadsheets:

A list of Generic NMEA Sentences, which cover everything I need.

Nexus NX2 Settings
Note: I am still fussing with NMEA outputs to get the best result.

Garmin GPS Settings

Furuno Radar/Plotter Settings

Simrad Autopilot Settings

Fugawi Settings

Brookhouse Mux Settings

Milltech AIS settings


This drove me nuts.

I tried SeaClear, and other packages, and it didn't happen. I spent many hours capturing NMEA log files, and it only happens when Fugawi is reading from the Nexus NX2 server.
The Fugawi log files said it was recieving bad position information with a valid checksum. Capturing directly from the NX2 using Hyperterminal never found a bad sentence, and plugging the GPS into Fugawi worked fine. I was convinced that Fugawi had a bug, but they didn't think so.
I was about ready to toss Fugawi
and get Nobeltec VNS.

However, I needed to add a Brookhouse multiplexer to integrate the Furuno into the system, and also to integrate the Milltech AIS if necessary. Doing this allowed me to hook the Fugawi software into the RS-232 port on the Brookhouse multiplexer instead of the Nexus NX2 server, and the problem disappeared. So I still don't know if Fugawi has a bug, or if my NX2 server is screwing up the output. The NX2 server was purchased when the product was first released, and might have "Revision 1.0" firmware. I wanted to talk with the Nexus folks at the annual west coast Strictly Sail boat show,
but they didn't have a booth in 2008. Perhaps over time I'll figure this out.

Anyway, everything is working now. This is how everthing is connected in 2008:

The Milltech SR161 has an RS-232 output only,
so the 38400 baud differential RS-422 port on the Brookhouse multiplexer doesn't have any value at this time.
But it can also be used as a normal 4800 baud NMEA port.

The Milltech SR161 can accept 4800 baud NMEA on the RS-232 port, and integrate it with the AIS data, outputting a single 38400 baud stream. It requires a custom cable, which you can make yourself or buy from Milltech.

Back in 2005, I had put a spare VHF antenna on the radar mast, just as a backup.
Now it is for AIS. This means that I don't need a splitter on my main VHF antenna. Cool.

It made the installation really easy.

Note: I tried this, and discovered that it will convert the 4800 baud from the Brookhouse mux, but does not convert in the other direction. So all the route information and output from the laptop gets dumped, making this setup worthless. I'm back to two cables, and still playing with it.