I'm using an inexpensive seismometer to try and measure the effects of local HGV traffic on buildings. The device is connected to a Raspberry PI that has a Cirrus Logic Audio Card. The signal is fed through the Line In. I am saving the readings from the device as a WAV audio file via arecord:

arecord -c 1 -f S16_LE -r 11025 --max-file-time 86400 --use-strftime %Y-%m-%d_%H:%M:%S.wav

It works, I can normalize the WAV file in Audacity and see the waveform change as a HGV drives past. After reading a few articles about other experiments doing the same I see that I need to convert the readings from the device into peak particle velocity (PPV) and VDV (Vibration Dose Value) for any of it to make sense in terms of ISO/BS standards (BS7385 & BS5228-2 for example) and assessing the likely effect on a structure of local traffic vibrations.

That's where I get unstuck, how to convert the data I have into PPV / VDV? I don't know about a few things, like whether the the arecord sampling frequency and depth are correct, I probably shouldn't be normalizing waveforms in Audacity (i'm only doing that so I can see if it's working).

I do know that I am looking for frequencies between 15 and 150Hz and that my experiment isn't exactly scientific from the Lego Seismometer, a starting point for possible future more detailed data collection and analysis is all that I need.


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