Using a Velocimeter 45
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2.3.3 Initial preparation
Communication
Check that you have installed the software correctly according to the procedure in the previous
chapter, Instrument Software, and then follow this procedure to test the communication:
1. Using the enclosed cables, plug in the AC adapter, and connect the Vectrino Profiler cable and
USB converter to the USB port on your computer.
2. Start the Vectrino Profiler software.
3. Select Connect:Vectrino Profiler, and specify which port number to use, and communication
speed
4. Click on Apply to initiate communication with the instrument
Check the transducers
1. Fill a bucket with water and a little sound-scattering material.
2. Click the Start Collecting Data button. While the transducers are in the air, the velocity
measurement will look like random noise.
3. Immerse the transducers in the water, and observe the velocity, the standard deviation, and the
amplitude in counts. Note the change in the graphical view of the velocity when the probe is
lowered into the water. In the air the graphs are noisy; in water they should be smooth. Noisy
velocity graphs: If the velocity graphs remain noisy when the probe is immersed in water, try
varying the position of the probe, or add some seeding like dirt or small particles to the water.
4. Designed to act as a measurement quality assurance tool, the Probe Check function in the
software lets you inspect the region where the sensor makes its measurements by showing how
the signal varies with range. You can use it to diagnose and correct problems and to optimize
data collection.
2.3.4 Configuring a Vectrino Profiler
The Doppler tab in the software is used when configuring the velocity profiling parameters.
The Sampling rate determines how often velocity records are collected. Individual velocity samples
are collected at a rate related to the ping interval (related to the velocity range) and averaged over the
sampling rate period to produce a final velocity estimate. The Data rate bar shows the transmit
bandwidth being consumed for the given configuration. If the bandwidth exceeds that of the serial port
speed, the data will be buffered internally within the instrument before being transferred to the host
computer.
The Velocity range, combined with the Ping algorithm determines the appropriate ping timing
parameters to achieve the desired velocity. The Extended Velocity Active field indicates whether or
not the selected velocity range corresponds to dual PRF operation.
Three algorithm choices are available for the ping algorithm:
Max interval: Produces the longest possible ping interval to achieve desired ambiguity velocity and
sampling range. This is best used for smooth flow conditions.
Min interval: Produces the smallest possible ping interval to achieve the sampling range and, at
minimum, the desired ambiguity velocity. This is best used for turbulent measurements
Adaptive: Collects a long profile and examines the return echoes to determine where acoustic
interference is occurring. The ping rate is then calculated to achieve the desired ambiguity velocity
and sampling range while minimizing / removing acoustic interference. The adaptive ping interval
selection is carried out with every configuration performed so the ping intervals selected may vary
when the beam return signals change. This is the best general choice. The adaptive check allows
the ping intervals to be adjusted dynamically during data collection to account for changing
conditions within the environment. Options range from Once (perform adaptive check only during
the configuration phase at the start of acquisition; static checking) to 1/sec (dynamic checking).
The corresponding horizontal and vertical ambiguity velocities are displayed (assuming the probe is
facing down). The vertical ambiguity velocity corresponds quite closely to the beam velocity.
For point measurement instruments, the measured region starts at Range to first cell mm and is of
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