Sound and Vibration Measurement: First Demo of the test jig

26 Apr 2022

Sound and Vibration Measurement: First Demo of the test jig

For the Sound and Vibration Measurement Hat for Raspberry Pi road test, I'm reviewing Measurement Computing's IEPE Measurement DAQ HAT for Raspberry Pi.
Time to demonstrate the first setup of the Automated Vibration Test Jig.
In this video, the flow lets the vibration table shake from 20 to 40 Hz, with 2 Hz increment.
At each step, the MCC172 takes 32.768 samples, then calculates the RMS value of that result.
This gets written to a data file.

The video is real time. You will not hear the lowest frequency because my microphone (and your speaker) don't capture that. You can see the sample speed of the DAQ by looking at the LED blink time.
Excel output attached:

daqhatmcc172_0.xlsx

Link to all posts.

Jan Cumps over 3 years ago in reply to Jan Cumps

... and with a few harmonics in view:
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Jan Cumps over 3 years ago in reply to Jan Cumps

With 512 samples / sec, 2048 samples taken
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Jan Cumps over 3 years ago in reply to michaelkellett

FFT is working now:

90 Hz sent to the vibration table. Top is a realtime waveform, bottom is a non-real-time FFT over 10k samples, 50k sample rate.
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Jan Cumps over 3 years ago in reply to michaelkellett

going by using my hands to feel the resonance, I'd say the cabinet resonates around 50 Hz, 100 for the plate we mounted on top of it with the sensor attached to it.
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michaelkellett over 3 years ago in reply to Jan Cumps

That's showing the distortion at very roughly 3% (on the good curve).

Not bad for an open loop system - do you know the mechanical resonant frequency of the set up ?

MK
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