2021-07-18, 04:58 PM
NMEA0183 is not up to the task of decoding fishfinder information. That's not it's intent. With a fishfinder or other sounder device, there is usually a sonar module involved. I'm not familiar with your fishfinder, but when there is a sonar module involved (yours may be inside your unit, so I'll guess your transducer connects directly to the GPSMap?), there is usually some high bandwidth ethernet connection or video-type connection directly to or in the display. NMEA0183 is an ASCII text-based language that will never be able to decode that info. It's real purpose is to send the GPS & similar data it receives out to a VHF radio, laptop, or even SignalK. It operates at a very slow 4800 baud (0183HS is 38400 baud for AIS data).
Even DeviceNet (NMEA2000 at 250,000 baud) isn't up to the task of handling that big of data load. Fishfinders, like radars, require high-speed (ethernet or directly connected) interfaces with a device that understands how to decode that info.
Even DeviceNet (NMEA2000 at 250,000 baud) isn't up to the task of handling that big of data load. Fishfinders, like radars, require high-speed (ethernet or directly connected) interfaces with a device that understands how to decode that info.