This project contains a collection of tools for analyzing infra-sound. It was born when experiencing noise from a distant infra-sound-source.
This project is inspired by the work of many other people (see credits below).
There is a lot of theory about infra-sound and the involved issues, caused by the sound and the vivbrations. Actually infra-sound is in most cases a surface acoustic wave (https://en.wikipedia.org/wiki/Surface_acoustic_wave). Therefore measuring it requires measurement of structure-borne and airborne noise. From these measurements one can estimate the intensity, distance, and direction of the noise.
The ariborne noise is measured with a difference-pressure-sensor, see ...
The strucutre-borne noise is measured with a geophon, see ...
Both sensors (difference-pressure and geophon) are assembled with Peapberry-PIs. For assembly-instructions check the sub-pages.
When this project evolved, it became especially important to get a near-realtime, portable sensor-kit, which allows to measure frequencies and their intensity. Also it became important to derive law-consistent sum-ups for third-octave-frequency-bands.
So the largest effort in this project is the mathemetical analyzation and realtime-recording-code.
Work is still in progress, i hope to extend this project over time, i am currently thinking about:
You need for each sensor a Rasperry-PI. It makes sense to set up Bluetooth in PAN-Mode, which allows you to connect to the sensor from your mobile phone and check real-time-data. Some hints for bluethooth-connectivity.
You also need to setup PAN to be able to access network services like ssh or http from your bluetooth-connected phone.
use Bluetoothctl
Especially when running without network connectivity the Raspi looses its time quite fast. There are RTC-I2C-Devices avail, which can be connected to the second I2C-Interface of the Raspi.
It also makes sense to setup Wifi, you know better probably.
After setting up the system, just wire up the devices and perform the following installation steps.
# not sure it this is required to pull
sudo apt install gh
gh auth login
git clone ...sudo apt install i2c-toolscc i2c_read_test.c -li2c
cc i2c_read_test.c -lwiringPi -li2c
rsync -v --remove-source-files -r -d pi@raspberrypi:/home/pi/i2c/data/ . cd sensor-control
autoconf
autoreconf --installThis is the recording-service, responsible for communicating with te device and recording the data.
python3 -m pip install numpy matplotlibcd geophon/infra-sound-recoder/service
sudo cp infra-service.service /etc/systemd/system
sudo systemctl daemon-reload
sudo systemctl enable infra-service
sudo systemctl start infra-servicecd geophon/infra-sound-recoder/service
sudo cp infrasound-recording-service.service /etc/systemd/system
sudo systemctl daemon-reload
sudo systemctl enable infrasound-recording-service
sudo systemctl start infrasound-recording-serviceThis is the web-service, responsible for providing the web-interface to access the statistics data.
sudo apt-get install libopenblas-dev
python3 -m pip numpy matplotlib httpservercd geophon/infra-sound-recoder/web-service
sudo cp web-service.service /etc/systemd/system
sudo systemctl daemon-reload
sudo systemctl enable web-service
sudo systemctl start web-service