1835 GPS and AIS seem mutually exclusive

wayne hoath

New member
I have an 1835 radar. The radar already has the heading provided to it from the autopilot. I am bring in AIS and GPS from my vesper watchmate 2.0 AIS transceiver. By default this out puts the NMEA 0183 data at 138400 baud rate. If I leave this baud rate at default then the AIS targets appear on the radar screen but no GPS is displayed. If I set the baud rate to 4800 then I get the GPS on the radar screen but not the AIS targets.

Thinking that it must need the GPS at this lower baud rate I bought a Quark-Elec A033 multiplexer which allows me to take in the NMEA data from the vesper at one rate and put it out at 138400 for the AIS on NMEA port 1 and 4800 for the GPS to NMEA port 2 on the Radar. I'm not at this point filtering the sentences so both ports will be getting all of the data at different rates. So this doesn't work. I still get the AIS targets but no GPS.

Do I need to filter the data from the multiplexer so that it only gives out the GPS sentences at 4800 to NMEA port 2 on the radar? I am guessing so but would be good to know before I go down that rabbit hole.

Last edited:
The 1835's display has two data connections. You could leave the heading connection alone and use the 2nd connection for the Vesper at 38400.
No multiplexer involved.
It would seem like you'd need AIS and heading for AIS targets to show up in the right spots on your screen.

Maybe there is something in the vmAIS vesper software to configure the AIS tranceiver which data it sends on 0183?