Vaisala WMT52 - Manual (Page 27)

Chapter 3 ______________________________________________________ Functional Description
VAISALA_______________________________________________________________________ 25
Depending on user selection the wind speed extreme values can be
computed in two alternative ways; either with the traditional minimum/
maximum calculation or with the 3-second gust & lull calculation
recommended by the WMO (World Meteorological Organization). In
the latter case the highest and lowest 3-second average values (updated
once a second) replace the maximum and minimum values in reporting
of wind speed, while the wind direction variance is returned in the
traditional way.
The WMT52 constantly monitors the wind measurement signal quality.
If poor quality is detected, the wind values are marked as invalid. If over
half of the measurement values can be considered as invalid, the last
valid wind values are returned as missing data. However, in the SDI-12
protocol the invalid values will be marked as zeroes.
Heating (Optional)
Heating elements located inside the wind transducers keep the wind
sensors clean from snow and ice. A heating temperature sensor (Th)
controls the heating. Th is measured inside the sensor, where
temperature is much higher than the ambient temperature (Ta).
Three fixed temperature limits, namely +10 °C, +4 °C, and -50 °C
(+50 °F, +39 °F, -58 °F) control the heating as follows:
0806-010 Figure 8 Heating Control