Vaisala WS425 - Manual (Page 49)

Chapter 4 ________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 49
Wind Direction Coast Threshold
At very low wind speeds, the measured wind direction is meaningless.
Therefore, you can specify a direction coast speed. When the measured
wind speed drops below the direction coast speed, the calculations use
the last wind direction that occurred while the wind speed WS at or
above the direction coast speed to average wind direction. You can
specify a direction coast speed between 0.0 and 9.9 units of
measurement. Use 0.0 if coasting is not required.
For example, the direction coast speed = 2.0. Consecutive measurements
are as presented in Table 12 below.
Table 12 Consecutive Measurements of Wind Direction
Measured Wind
Speed Measured Wind
Direction Wind Direction Used for
Averaging
3.5 350 350
2.5 340 340
2.2 340 340
1.9 175 340
(coasting)
1.2 045 340 (coasting)
2.1 345 345
NOTE The wind direction coast threshold can be set to a non-zero value only
when the averaging method (configuration parameter 4) is set to scalar.
Head Orientation
The sensor can be installed either transducers up or transducers down.
The wind direction calculation requires that the installation position is
configured correctly to the sensor. The installation of the sensor upside
down should be constructed in a way that prevents water from entering
the sensor connector.
Bit Rate
The following options are available:
- 1200b
- 2400b
- 4800b
- 9600b
- 19200b