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Tips and Troubleshooting
In this section, some of the problems that could arise with the use
of the instrument are mentioned as well as recommendations for
solving each of them are described.
Sampling Frequency and frequency resolution
The sampling frequency and the number of collected points will
affect the accuracy and precision of your results.
The sampling frequency will determine the maximum frequency that
will be useful in the frequency spectrum, which is known as the
Nyquist frequency. This value is one half of the sampling frequency
and data from the frequency spectrum higher than that are useless.
In order to be able to obtain the resonance of the specimen, you
need to select a higher sampling frequency than the expected
resonance frequency (for concrete usually less than 10 kHz, so
sampling frequencies of 20 kHz or higher are recommended).
Contact accelerometer
It is important to place the accelerometer in contact with the
specimen. Checking accelerometer contact before impact the
specimen with the hardened steel ball is recommended. Coupling
between accelerometer and specimen assures proper testing
results. For more information, please refer to the recommendations
presented in the Operating Instructions chapter.
Trigger level
The trigger level should be adjusted to the particular testing
conditions. The level should allow you start recording the vibration
of the specimen right after the specimen is hit with the hardened
steel ball. A very low trigger level would trigger the system with a
different event than the impact of the steel ball. On the other hand,
a very high trigger level will not trigger the system even after it is
impacted with the steel ball. So, the user shall decide which trigger
level is more convenient for the particular testing conditions.
Gain
The gain allows you to control the amplitude of the received signal.
