700-SDI-RADAR-300WL-Man Rev 2 11 Apr Mar 2022
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Part# 21371
2.2
MEASUREMENT QUALITY INDICATOR
The 300WL constantly calculates signal parameters in the signal processing algorithms and will
report measurement quality (signal quality) with the measurement data report. The quality indicator
value can be used to better interpret data in the analysis software.
The Measurement Quality Indicator (signal quality) values are:
3->unacceptable,
2 ->low,
1->good,
0->excellent
It is up to every user to interpret the quality indicator value for their application based on their
knowledge of the site. The general recommendation is that measurements with quality indicator 3
cannot be trusted, value 2 could be questionable and values 1 and 0 are very good and accurate.
For example:
A radar is mounted on a railway bridge (a common application).
Measurements will be of high quality most of the time except when a train is passing due to
the extensive vibrations. The radar will still report measurements, but the values could be
skewed. However, the measurement quality indicator value for measurements during that
time frame will be higher, indicating the data should be questioned.
2.3
RAIN AND WIND
The 300WL has integrated internal software filters to filter out effects of rain, fog or wind. However,
these filters have some limitations imposed by environmental conditions (i.e. precipitation). The
majority of measurement inaccuracies caused by environmental factors can be solved by proper
sensor installation.
For rain and snow suppression, the most effective solution is to mount the radar so that the flow
meter points upstream and the water flows towards the radar. As rain falls down and the radar is
tilted downwards, rain droplets will move away from the radar, while the water flows towards the
radar. The radar can then easily distinguish the water movement from rain movement. To further
improve rain filtering, the radar should be configured to report only incoming direction of water
flow. In this case, the radar will completely ignore all movement with direction going away from the
sensor. However, for sites that has water flow in both directions, the radar sensor should be
configured to report both incoming and outgoing flow by selecting the “both direction” setting in the
radar sensor.
Additional rain suppression can be implemented by mounting the radar below a structure so that
the first 1 to 2 meters in front of the radar are free of rain. As the energy of the radar beam drops
exponentially with distance, the radar is most sensitive to the rain directly in front of the radar. If the
radar instrument is being mounted on a bridge, if possible, it should be mounted below the bridge
instead of on the side of the bridge, so that the bridge provides cover from the rain directly in front
of the instrument.
