THEORY OF OPERATION
The vibration system operates by setting an analog trigger and window in the hardware DAQ device. This provides the basis
of the trigger detection. To provide the phase delay, the measured period is multiplied by the selected phase to establish
the delay. For example, if the frequency is measured at 1000Hz, and the requested phase is 180º, the trigger delay will be
set at
(1/1000Hz)*(180º/360º) = 0.001s * .5 = 500µs.
This is important because it means that the phase delay has a slight lag. If the frequency of a cycle varies greatly from that
of the previous cycle, the calculated delay in µs will no longer correspond to the requested phase in degrees. Very noisy
signals will be subject to the same problem as the trigger will be found at slightly different points in each cycle.
Because of this effect, it’s important to work with motion – and signals - that are very close to steady-state cyclical. For
assistance optimizing your test, please contact Technical Support.
SUPPORT
If you have any questions about this Application Note or any other questions, comments, or concerns about your CSI
system, please feel free to contact us at support@correlatedSolutions.com
or visit our web site at
www.correlatedsolutions.com.
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