Manual – Starflow QSD Model 6527B and 6537A
Unidata Manual - 6527B and 6537A Starflow QSD User Manual 08 05 2023.docx
Page 108
Legitimate velocity - some noise
Velocity too slow - only noise remaining.
17.14.
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 comes out of the water. A configuration setting can be used to switch off
the velocity operation of the Starflow QSD when the measured depth is so shallow that the
eyes are exposed. The Velocity Trace display will be similar to that for very slow velocities.
The ultrasonic depth transducer will only measure depths that are 40mm above the
ultrasonic eye, and the pressure transducer will measure down to 0mm. If it is important that
these very low flows be measured, then the Starflow QSD can be fitted into a narrow
channel or recessed into the bed such that all the Starflow QSD is underwater whenever
flow occurs.
17.15.
Interference to the Transducers
It is inevitable that bed-mounted instruments will become layered with silt or algae. They
may sometimes be affected by siltation or debris. The following effects have been noticed.
17.15.1.
Silt, Algae and Other Soft, Saturated Materials
When covering the transducers with a 1-2mm thick layer, they appear to have little effect on
the signals logged. Provided the material is flexible and saturated, the ultrasonic signals can
be transmitted and received through it.
