Manual – Starflow Ultrasonic Doppler Instrument
Model 6526
Unidata Manual - 6526 Starflow User Manual Issue 17 01 2020.docx
Page 56
12.2.8
Velocities Too Slow to Measure
When velocities fall below the minimum level the Doppler can measure (21mm/sec) signals are not
processed. However, under certain conditions signal noise is processed, a messy signal
interpreted and a higher velocity results. Usually the processed quartile is too large. Using the
filter will prevent most of these signals.
Legitimate velocity - some noise
Velocity too slow - only noise remaining
12.2.9
Measuring Velocities in Very Shallow Water
Poor quality velocity data will result if the water becomes so shallow that the top of the eyes of the
transducer come out of the water. A configuration setting can be used to switch off the velocity
operation of the Starflow when measured depth is so shallow that the eyes are exposed. The
Velocity Trace display will be similar to that for very slow velocities.
The depth transducer will measure depths down to about 5mm. If it is important that these very
low flows be measured, then the Starflow can be fitted into a narrow channel or recessed into the
bed such that all the Starflow is underwater whenever flow occurs.
