Tuesday, March 1, 2011

What a great question about how WatchMate’s multiplex NMEA data!

Question: I am considering the WatchMate 850 transponder and have a question regarding the NMEA183 data to a chart plotter. Does the heading data on the 4800baud input get combined with the 38400 baud AIS output data so that the heading data can be used by the MARPA radar function on the chart plotter? I am using a Raymarine C80 plotter and if the heading data is combined with AIS data it will eliminate the need for a NMEA data multiplexer. If so this will make the WatchMate 850 Transponder / C80 combination very cost effective and versatile.

Answer: Yes. The input NMEA data is multiplexed into the output stream. You can feed any NMEA-0183 instrument data you wish, such as heading, and it will appear in the output data stream along with the internally generated AIS and GPS data. We have many customers using this with Raymarine C-series displays since they only have a single NMEA input. In the same way, you can also use the WatchMate as a source of GPS data for your C80 and/or as a backup GPS receiver for your C80. The USB port receives this data as well, so the WatchMate can also be used as a source of GPS, AIS and instrument data for computers.

1 comment:

  1. Worth mentioning is that in installations like ours on s/v RED where there is already a NEMA multiplexer, you can choose *not* to multiplex the NMEA data to the output thus providing a "clean" AIS-only output to the multiplexer.