Q&D Magnetometer Calibrations

Magnetometer, Turntable, Wireless, Plot Circle, Calibrate

The hardware

A magnetically agnostic turntable is used to spin a three axis magnetometer. The magnetometer readings are read by a Pico (or equivalent) and transmitted wirelessly to a web page (served by the Pico). Puck?

The webpage has the following elements:

• A slider bar that controls the radius of a circle drawn on the page.
  
• Radio buttons to select the magnetometer axis pair to plot X-Y, X-Z, Y-Z.
  
• Three slider bars for the axis offset values and boxes that display the values.
  
• Three slider bars for the axis gain values and boxes that display the values.
  
• A control to limit the size of the data buffer
  
  

As the data from the magnetometer are acquired the selected axis pair are plotted as an asteroid belt around the origin of the graph. The offset sliders are adjusted to center the asteroids. The cursor circle and the gain sliders are adjusted to visually best fit the data to a circle. The values in the gain and offset boxes are then used for the magnetometer calibration values. It is conceivable that local distortions in the magnetic field could be detected and visualized with such a system.