Geolux RSS-2-300W, User Manual

RSS-2-300W User Manual

7

RSS-2-300W Non-Contact Surface Velocity Radar

Water surface directly below the sensor should be clean of vegetation, rocks, sand deposition 

or other obstacles that could affect measurement.

Surface velocity radar beam will cover an elliptical area on the water surface. The radar 

reports average surface velocity of the covered area and instrument uses complex Kalman 

filters with physical modelling of the water flow to give stable measurements even under 

turbulent conditions. However even the moderate waviness of the water surface will improve 

the measurement, if the water flow is strongly turbulent, fluctuations in measured data could 

be expected as well as somewhat reduced measurement accuracy. If strongly turbulent flow 

can be expected at monitoring site, then the filter length of the radar should be configured to 

120 or more.

4.2. Measurement Quality Indicator

Geolux RSS-2-300W instrument is constantly calculating various parameters of the signal in 

the signal processing algorithms and will continuously, along with measurement data, report 

the measurement quality. Quality indicator value is in range from 0 (the best quality) to 3 

(the worst quality) and can be used to interpret data in the analysis software with better 

understanding and confidence.

For example, when the radar is mounted on the railway bridge, one of common applications, 

measurements will be very good quality most of the time except when train is passing the 

bridge due to the extensive vibrations. In this case radar will still report measurements but 

values could be quite wrong, but also the measurement quality indicator value will go up 

to the higher value. It is up to every user to interpret the quality indicator value for their 

application, but 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.

4.3.  Rain and Wind

Geolux RSS-2-300W instrument has integrated internal software filters to filter out effects 

of rain, fog or wind both for surface velocity. These filters however have some limitations. 

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 it 

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.

Influence of the wind on the accuracy of measured data is, in most cases small and can be 

neglected. The only exception is strong wind as it will create surface waves that are traveling 

in different direction from the water flow. This can affect surface measurement accuracy.