User`s guide

USER'S GUIDE____________________________________________________________________
30 __________________________________________________________________ M211095EN-C
Scalar Averaging
When scalar averaging has been selected, WMT700 calculates wind
speed and direction averages by adding up each wind measurement from
the averaging time and then dividing the sum by the number of
measurements. The time between each consecutive wind speed and wind
direction measurement is 0.25 seconds.
Wind direction is a circular function with a discontinuity at the north,
where 360 degrees is equal to zero degrees. For instance:
359 ° + 5 ° = + 4 °
0 ° - 5 ° = 355 °
WMT700 translates wind direction to a linear function to determine the
wind direction average. For instance:
359 ° + 5 ° is translated to 364 °, which is then further converted to +4 °
for output.
0 ° - 5 ° is translated to 355 °.
This ensures that the wind direction average stays representative of the
true situation even if individual samples occur on both sides of the zero
direction.
If the data acquisition system requests data before the initial averaging
time completes, the sensor returns the most recent complete measurement
data.
Figure 9 on page 31 shows an example of averaging wind direction when
the m
easured wind values are 355 ° and 10 °. The resulting average is 2.5
°.