Manual – Starflow Ultrasonic Doppler Instrument
Model 6526
Unidata Manual - 6526 Starflow User Manual Issue 17 01 2020.docx
Page 58
Debris on the Sensors
A similar effect to saltation can result from leaves and fine
debris covering the sensors.
If the sensors are partly clear the recording is not affected.
However one leaf lying across the two velocity sensors is
enough to corrupt the signals and produce the type of
histogram produced from a buried sensor.
Disruption of the Flow Pattern by Debris
Larger debris in the vicinity may affect the logged values by changing the velocity distribution in the
field of view of the sensor.
The flow distribution in the channel may no longer be laminar and the relationship between the
logged and mean channel velocity may be distorted. The histogram produced appears similar to
those described in 12.2.3 Measuring Unexpected Velocities on page 60 and 12.2.4 Measuring
Turbulent Velocities on page 61.
Blocking of the Signal Paths by Objects
One strategically placed solid object, such as a
rock, stick or other acoustically opaque material,
may block the path to either sensor blanketing
any signals. There will be a dominance of zero
signals however those below 20 mm/sec. are
discarded. The histogram will be distorted and
have a characteristic vertical face at 20 mm/sec.
