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I am wondering how compass calibration works / why e.g. drawing an 8 or rotating the phone to all 3 axis works (or at least shall work) - I mean I would understand the calibration process, if an application would say me: Point to north, then press that button down there, but you can start at basically zero knowledge for the app, just by rotating your phone! How is that done? Also, do I need to enter a special calibration mode or can I draw these figures (like the 8) directly in Google Maps? How does Google Maps know that I am not just really moving the phone but want to calibrate the compass? Thanks for any hint!

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Flagged as dupe, please don't post two separate questions for the same problem. Edit your existing question with new information; android.stackexchange.com/questions/30328/… – bigbadonk420 Oct 3 '12 at 21:59
Moving an object through a magnetic field can induce an electric current, which I'm guessing is being measured in this case. The figure 8 ensures that the phone is moving along every possible vector in a 2D plane, which ought to allow it to distinguish north from south. I think. As for Maps sensing it, that one's easy -- what other time do you make such an absurd motion with your phone? It's quite different from normal movements and ought to be simple to detect. – Matthew Read♦ Oct 3 '12 at 22:00
@bigbadonk420 This is not a duplicate, it's a completely different question. – Matthew Read♦ Oct 3 '12 at 22:01

1 Answer

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Compass calibration works by detecting the magnetic field intensity of earth. But sometimes due to strong interference from other electronic devices like transformers compass sensor may get wrong idea about the magnetic poles of earth and can point in wrong direction. So to ensure that it asks users to recalibrate compass by rotating in figure 8 direction so that it can judge the magnetic intensity in all directions and then from that data it deduces the actual poles of earth.

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