CRVW3 3-Channel Vibrating-Wire Datalogger
28
used (baseline values), a
CalHist
table will also appear showing calibration
values captured during the latest calibration event.
To ensure proper operation of the CRVW3, you should confirm that the
RecordNo
field of the
VW_Data
table is incrementing at the proper
measurement interval, and that the measurement data (frequency, temperature)
is correct. The
Time Stamp
field should also get updated as each measurement
is made. By confirming this operation in the lab, you have the opportunity to
resolve any problems as early as possible and in an environment more
favorable for troubleshooting.
The
Troubleshoot
tab is provided so you can see detailed information about
the vibrating-wire sensor measurements made by the CRVW3. You can
manually trigger a measurement test and see diagnostic results within a few
seconds. Select your channel of interest in the
Channel
selection box. Use the
Options
button to set the sweep excitation and frequency filtering window, and
also to set the excitation voltage level to be used during the test. Press the
Poll
button to initiate the test. Within a few seconds the results will be displayed on
the screen.
The
Spectrum
window shows the frequency domain response of the vibrating-
wire sensor. Peaks in the spectrum indicate the main frequencies at which the
sensor’s wire vibrated during the measurement. The strength of the peaks are
shown in the millivolt scale. Drag a rectangle on the viewing area to zoom in.
Press the
Undo Zoom
button to return to the initial scale.
The
Time Series
window shows the motion of the sensor’s wire (in millivolts)
during the measurement period as given by the changing magnetic field sensed
by the coil circuitry. Drag a rectangle on the viewing area to zoom in. Press the
Undo Zoom
button to return to the initial scale.
The main frequency reading is given in the
Peak Frequency
box in units of
Hertz (Hz). Other diagnostic readings are given to help assess the quality of the
reading:
•
Signal-to-Noise Ratio
: The amplitude (mV) of the strongest
frequency peak in the spectrum divided by the amplitude (mV) of the
2
nd
strongest frequency peak.
•
Decay
(Decay Ratio): The amplitude (mV) of the time-series motion
of the wire at the beginning of the measurement divided by the
amplitude (mV) of the wire motion at the end of the measurement.
This can also be approximately discerned by a study of the results in
the
Time Series
window.
•
Peak Amplitude
: The amplitude in millivolts (mV) of the strongest
frequency peak in the spectrum.
•
Noise Frequency
: The frequency (Hz) of the 2
nd
strongest frequency
peak in the spectrum.
•
Thermistor
: The measurement of the thermistor’s electrical resistance
in units of Ohms.
Summary of Contents for CRVW3
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