Magnetometers are devices that employ diverse methods to determine specific aspects of magnetism like strength, direction or changes in relative. Combining these techniques and applying certain mathematical principles, underground structures and other structures that are hidden can be identified without risking damage to any object that is below the sensor. This is the reason Markus Opitz decided to create a large-scale magnetometer made of simple parts to help map the structures within his property.
The fundamental design of the device is made up of a frame that is constructed out of several planks of wood with the wheels on its bottom as well as a long aluminum tube to house the sensors. To collect raw data, Opitz started by integrating seven Hall effect sensors along with the digital compass as well as the Arduino Mega.
Coordinates are calculated through the built-in GPS module. They are then recorded on an SD card, along with readings from the connected sensors. In addition, the current location is determined by digital compass, and then displayed along with other information on a OLED screen that measures 128x64px.
After moving the device about an outdoor area for a few minutes and collecting plenty of information, Opitz loaded the logs into qGIS, which combines the headings and magnetic value and coordinates as well as an image of a satellite map to create one image.
To read more about this project, you can view Opitz’s write-up on Instructables.