USER'S GUIDE ____________________________________________________________________
98 __________________________________________________________________ M210543EN-F
PWD22/52 Reports Precipitation When
There Is None
In temperatures under 0 °C, only the optical measurement is used in
detecting precipitation. In temperatures above 0 °C, the RAINCAP
®
detection is used to cross-check the optical detection -- false detection
can only be caused by problems in both measurements.
1. Check that there are no flashing lights close to PWD22/52.
Flashing lights may cause PWD22/52 to detect peaks in the optical
signal.
2. Check that there are no foreign objects in the sample volume. Tree
branches or other moving objects may cause sudden changes in the
scatter signal.
3. Check that receiver is not facing cars passing by. If the sun beams
reflect from passing cars towards the receiver, this could cause
false precipitation reports, especially in winter. These short sun
beam reflections can cause short spikes to the PWD22/52 optical
signal and they are interpreted as light snow.
This might happen if there are sharp changes of the lighting
condition of the ground where the receiver is looking. If the area
where the receiver is looking at is bright and shiny and passing cars
cause shadows to that area, this can cause similar short spikes to
the receiver signal.
4. If the false detection has occurred in temperatures above 0 °C,
RAINCAP
®
does not function correctly. Clean the RAINCAP
®
sensing surfaces.
PWD22/52 Reports Frozen Precipitation
during Rain
The ratio of optical intensity measurement to the RAINCAP
®
measurement is too high.
1. Check the optical calibration and RAINCAP
®
operation.
2. If everything else seems to be functioning correctly, change the
parameter settings.
- If possible, check the accumulated water sum against a reference
rain gauge. This will indicate how close the Rain intensity scale
is to the optimal value. Decrease the scaling factor if the
PWD22/52 rain amount is too high.
- Otherwise, increase DRD scale (the WSET command).
To Next Page
Loading...
