The NMEA DBT datagram provides the current depth under the transducer.In new designs, this datagram is frequently used to replace the DBK and DBS datagrams.
Format
$--DBT,x.x,f,y.y,M,z.z,F*hh<CR><LF>
Description
All depths are measured from below the transducer face.
1
$—: Talker identifier
2
DBT: Datagram identifier
3
x.x,f: Depth in feet
4
y.y,M: Depth in metres
5
z.z,F: Depth in fathoms
6
*hh: Checksum
Tip
If you need the depth below the keel, use the NMEA DBK datagram.If you need the depth below the surface, use the NMEA DBS datagram.