The new Lego seismometer arrived last week, I’m really impressed by it compared to the first slinky version I got two years ago.
It’s much more sturdy and takes up much less space than a slinky seismometer I tried previously. It would make a great educational experiment in the classroom.
You can see it plugged into a Raspberry PI computer (the thing with lights). The Rpi has a sound card added so that it can record the analog input and convert it into a digital file WAV file. Think of it like a microphone that only records low frequencies/vibrations. It works, I sat there and watched a HGV go past then looked at the waveform. I have it recording continuously.
The advantage of this device is that it’s easier to see traffic over time and manipulate the data. The disadvatage is that it’s only one axis (z), whereas the EnviroPhat I tried could do all three (xyz).
I’m at the stage now where I need to be able to relate the data into a value that has some real world meaning. 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 Vibration Dose Value (VDV) for any of it to make sense in terms of ISO/BS standards (BS7385 & BS5228-2 for example – yes there are standards for what i’m trying to measure) in assessing the likely effect on a structure of local traffic vibrations. I’ve asked the question on various forums online.
I know the device isn’t exactly scientifically accurate (as it’s made from lego) but all I want is a sense of what might be occurring from local traffic and to maybe spark further more detailed analysis by other groups.
