For those not familiar with SH plotters: SH got away from actual GPS antennas, the kind with coax and a TNC connector, and got onto “smart antennas”. This is a GPS unit that is self-contained in the mushroom case and sends NMEA data down the wire. These are nice because you can splice the cable like any other wire and also use it for other things. Right now I have mine spliced to send NMEA data to other places besides the plotter and get power directly so it works if the plotter is on or off or not even there. I am not sure if I am going to keep this or do something else, but FYI if you see an old plotter with a “smart antenna” for cheap, you can use it as a nice GPS with or without the plotter. Also if the plotter is cheap because the GPS is missing, you can get a cable and splice it in to your existing GPS data ;)
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Della Barba, Joe via CnC-List Sent: Monday, October 30, 2017 11:03 AM To: cnc-list@cnc-list.com Cc: Della Barba, Joe <joe.della.ba...@ssa.gov> Subject: Stus-List AIS improvement + general rewiring The old AIS was tested on my Sunday afternoon sail and got about 15 targets. It is now off the boat to be shipped to its new owner. The new one is on the way, a Digital Yacht AIT1500. So now I need to redo the various NMEA connections and the first thing I am trying to figure is the DSC-in signals. The VHF has a DSC-out and apparently the new AIS does too, but it does not seem to be documented. The manual mentions once receiver switches back and forth between DSC and AIS, but does not mention what sentences it sends out or on what outputs. My initial plan is to have the VHF DSC out go to the AIS NMEA in and then it can combine DSC messages it hears with whatever the AIS picks up. I am planning for now for the AIS to provide data for the nav computer and VHF, the cockpit plotter will get the AIS info from the AIS and GPS data either from its own receiver or the AIS unit, and the APRS will have its own low power GPS so I can turn everything off but APRS when I am not on the boat. More to follow, but that is plan so far. One frustration is for some reason the CP180 plotter will NOT take a GPS fix on any input but 4800 baud port 3, so even though the AIS will send all the GPS data along with AIS on 38K baud, the plotter won’t read the GPS sentences at that speed on ports 1 or 2. OpenCPN has no such restriction, so one connection will do for that. Joe Coquina C&C 35 MK I
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