iPhone app that helps with large rover (mower) Compass calibration debugging

On my large rover, compass calibration is impossible when the GPS puck and the PX4 are close to the vehicle. If I unplug them and move them a few meters away, everything is fine. In trying to determine where to put the GPS puck and/or Pixhawk (i.e. the compass or compasses), I wanted to know where around the vehicle the magnetic field is distorted by motors, batteries, steel tube framing, etc., I found this app Sensor Kinetics: https://itunes.apple.com/us/app/sensor-kinetics/id579040333?mt=8 It displays on my iPhone the magnetic fields in a real-time chart. Very cool. So it became a no-brainer to measure the mag fields around my rover and determine where (seems like 4-5’ away, vertically) the mag fields are not distorted and hence a safe place to mount the magnetic compass.

@ktrussell you should check it out!

Hopefully this lesson will be useful to someone else. Without that app, after all, it’s quite difficult to see the magnetic fields…

Happy tinkering,



This is awesome, Chris! I will definitely try this.

Edit: I just searched for this for my Android and found I already had it installed! Must have been long ago. I know I have not used it with my mower…but I will!

I think I am done with compass once I test the RM3100. Its currently back ordered from Drotek. But this is what I think will solve our mower heading problems for good. Dual GPS RTK with Heading


I like that idea! I may do the same eventually.