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post #1 of Old 01-25-2011 Thread Starter
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Sending GX2150 AIS NMEA data to chart plotter over Bluetooth

I thought I would put in an update on my instrumentation plan from what I had posted on another thread. I have a much smaller and simpler boat than many of you, but nevertheless maybe someone else can benefit from seeing what I'm doing, and/or offer advice on what I can do better. As you can see, I have relatively little instrumentation, but I am interested in doing as much with what I have as possible without taking out a second mortgage to finance it. Most of this is driven by the new GX2150 VHF/AIS radio that I have on order, and since many others may be adopting AIS in the future, this might help someone.

I tested most of the components shown on the other thread over the past week. The Seatalk-NMEA bridge from Raymarine worked fine, but it has a defect that will require it to be returned (glad I got it from WM, and not from an ebay seller). Since its only purpose was to get Depth data into NMEA for display on the Netbook, I've decided it's not worth the cost or hassle. Part of this is because I learned from the Standard Horizon tech support guy that the GX2150 will not pass through the depth sentences over NMEA as I had previously hoped - it will just ignore them. So the only way to get depth and AIS into NMEA is to add a multiplexer. And a mux/SeaTalk translator is more than I was willing to pay at this time. Maybe I'll do that next year if I add an electronic wind gauge.

Also, my prior design was too dependent on having the Netbook turned on all the time to pass the GPS data to the radio. DSC and AIS are important enough that they deserve a dedicated GPS, so I've ordered a Garmin 18x LVC. I plan to configure this so that the other GPS in the cockpit can be tethered to the Netbook and passed by Bluetooth to the AutoPilot if I want to run in track mode. The Netbook would have to be on for that, but I will do this only rarely. I've left the Baud converter in the design because it allows me to run the AIS input at 38400 baud. According to the GX2150 manual, doing this causes both the AIS and DSC targets to multiplex onto a single port at 38400 baud. Alternatively, I could eliminate the baud converter by running the 18x GPS data into the radio at 4800 baud, but then the AIS and DSC targets would come out from the GX2150 via two separate ports at two different baud rates according to the GX2150 manual. (Note that the GX2100 is limited to operating in this mode, which is why I am waiting for the GX2150.)

So here is my schematic - comments welcome:

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2001 Catalina 34MkII Breakin' Away (at Rock Hall Landing Marina)
PO of 1998 Catalina 250WK Take Five (new owners relocated to Baltimore's Inner Harbor)
1991 17' Trophy (Lake Wallenpaupack)
1985 14' Phantom (Lake Wallenpaupack)

Last edited by TakeFive; 01-25-2011 at 08:50 PM.
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