Airmar LB150 - Manual (Page 21)

LB150 WeatherStation Technical Manual revision 0.013
Proprietary and Confidential
PRELIMINARY - DRAFT 18
NMEA 0183 TRANSMITTED SENTENCE
$WI
MWV
Summary
NMEA 0183 standard Wind Speed and Angle, in relation to the centerline of the
front of the vehicle.
Syntax
$WIMWV,<1>,<2>,<3>,<4>,<5>*hh<CR><LF>
Fields
<1> Wind angle, 0.0 to 359.9 degrees, in relation to the centerline of the
front of the vehicle, to the nearest 0.1 degree. If the data for this field
is not valid, the field will be blank.
<2> Reference:
R = Relative (apparent wind, as felt when standing on the
moving vehicle)
T = Theoretical (calculated actual wind, as though the vehicle
were stationary)
<3> Wind speed, to the nearest tenth of a unit. If the data for this field is
not valid, the field will be blank.
<4> Wind speed units:
K = km/hr
M = m/s
N = knots
S = statute miles/hr
In the LB150 WeatherStation, this field always contains "N" (knots).
<5> Status:
A = data valid; V = data invalid
Default State
MWV(R): Enabled. Transmitted twice per second.
MWV(T): Disabled. Transmitted once per second when enabled.
Notes
Depending on the contents of the Reference field (field <2>), this sentence
provides either relative (apparent) wind or theoretical (true) wind data, both in
relation to the front of the vehicle. Although it is conceivable that both of these
forms could be useful simultaneously, the LB150 WeatherStation by default only
outputs this sentence once in the MWV(R) form.