In the schematic the "NMEA device" is any other device you may have that reads NMEA
, like maybe an autopilot
, multiplexer, etc. It's optional.
The AIS receiver parses the AIS data into NMEA "sentences" . . . these can be read by any "NMEA device" which would include a software package that speaks NMEA and runs on a laptop. There are many of 'em. OpenCPN displays AIS data beautifully as ships with tracks and their Closest Point of Approach to you marked clearly. Of course this assumes you are also feeding GPS
data about your own ship to the software. This can mean that you need an NMEA "mulitplexer" to combine the NMEA streams, or sometimes not, like if you have a USB GPS antenna
and a USB AIS receiver and two USB ports
on your laptop.
Hope this helps