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7.3. Pre Measurement Diagnostics
Pre Measurement Diagnostics is an essential step in the measurement process to
ensure accurate and consistent measurement results. The functions evaluated in pre-
measurement diagnostics are the same as discussed in Office Diagnostics.
a) The functions that are evaluated during diagnostic test process are located under
the
Utilities
menu.
b) The functions that are of key importance during the pre-measurement diagnostic
tests are System Clock, Velocity Data, SNR Data and Beam Check functions.
c) It is recommended that Pre Measurement Diagnostics should be performed
before each measurement is started.
d) To verify the Internal System, Raw Data and Beam Check functions place the
FlowTracker2 probe in moving water well away from any underwater obstacles in
the region of the measurement section.
e) The variables that are evaluated during the diagnostic tests are listed in
Function
• Verify if the internal system clock date and time is correctly set and adjust if
required.
• All data sets recorded during a FlowTracker2 measurement receive a date
System
and time stamp,
Clock
• Date and Time is essential Metadata in the processing and application of
measurement results.
• Verify if the available memory is sufficient for performing a measurement,
• Insufficient memory on the recorder could affect the measurement operation
Recorder
and or recording of measurement file.
• Evaluate the battery voltage and capacity based on the battery type selected,
Battery Data
• Insufficient power supply could affect the measurement operation.
• Evaluate the GPS information received, with the focus on number of satellites,
GPS Data
and HDOP values. This will indicate the level of accuracy of the GPS
measurement.
• The raw data displayed of all variables is updated once per second.
• Velocity, data should appear reasonable for the environment (short term
variations are expected and are most likely real).
• SNR, data should ideally be above 10 (units are dB), but measurements can
Raw Data
be made as low as 3-4 dB.
Display
• Temperature, data should reasonable to the environment. Temperature data
is used for sound speed calculations and can affect velocity data
Principle of
• Place the probe in moving water well away from any underwater obstacles;
Automated
follow the on screen instructions for the test. Perform Beam Check
Beam Check
measurement as described in
• Automated Beam Check, review of Automated Beam Check results see
Beam Check
Automated Beam Check
• Beam Check, review of Beam Check results see
FlowTracker2 User's Manual (January 2019)
Table 7-4 - Pre Measurement Diagnostics
Operations).
,
111
Verification
Beam Check
Operation.
Beam Check
SonTek – a Xylem brand
Table 7:4.
(see
.
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