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Interpreting ADXL325 Data Results

Question asked by groger on May 23, 2015
Latest reply on May 25, 2015 by groger

Hello:

 

I'm hoping someone could set me on the path of understanding on the best way to interpret the accelerometer data I've gathered. I used the evaluation board EVAL-ADXL325Z to log data.

 

For the power supply, I used a 12V battery pack, and fed into a 3.3V linear regulator. This fed 2 boards, the EVAL-ADXL325Z, and the AD8244-EVALZ buffer. The output from the accelerometer went to the buffer, then to a Measurement Computing USB DAQ module. There, I sampled at a 200Hz rate in single-ended mode, and logged all 3 axis.

 

The machinery that the unit was attached to for the test had a high vibration component in it, as evidenced from the data file output. I can see the maximum and minimum magnitudes.

The question is, how can I use this data to determine what the vibration component is from the engine?

As the engine is revved up, the magnitude of the vibration increases, as expected. While the unit is moving, there is a shock component occurring, and it appears the vibration is still logged in conjunction with the shock. How should this be separated as to correctly evaluate the shock from vibration?

 

Also - should the data file be put through some filtering, as it went directly to the DAQ, logging at 200Hz? I realize the ADXL board has a filter cutoff of 80Hz (left it stock) but what about aliasing?

 

I have a program that can do some post-processing (Scope DSP) but..."the tool in the hands of a fool....is just bad news"  8-)

 

Thanks for any (and all) help.

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