Actually OkMap is able to understand only a subset of NMEA sentences using one serial connection. These sentences are the most used in GPS communication. A dept sounder, connected via a serial port, uses other sentences. Does the dept sounder return the geografic position also? (otherwise OkMap should use two serial connections). Where is possible to find the thecnical specifications of serial connection and the NMEA sentences format? In every case it would be difficult for me to test this.
OkMap should receive data via two serial communication ports. One port (already managed) receives NMEA sentences from a GPS device. The second port (to be implemented) should receive depth data. The first port receives data every 2-3 seconds. I don't know the frequency of depth data. OkMap can associate the last position data received from GPS and the last depth data received from second serial port. I know that there are NMEA standard for depth data also. The only problem is to have all hardware necessary for implementation and tests. If some depth sounder manifacturer is interested in this.... Do you know someones?