NMEA MWV datagram format
The NMEA MWV datagram provides the direction from which the wind blows relative to the vessel's centre line.
Format
$--MWV,x.x,a,y.y,b*hh<CR><LF>
Description
1 $—Talker identifier
2 MWVDatagram identifier
3 x.xNMEA MWV (0 to 359 degrees)
4 aReference
•  R = Relative
•  T = Theoretical
5 y.yWind speed
6 bWind speed unit (K/M/N/S)
7 *hhChecksum