We knew this, but iOS compass is quite inaccurate; but consistently?

robgendreau

Explorer
Most of us who have used compass and/or nav apps in iOS have seen warnings about the poor quality of the onboard compass. Just ran across some more testing of that, courtesy of TidBits and other web sites.

http://www.techhive.com/article/2055380/six-iphones-tested-and-they-cant-agree-on-true-north.html

http://gizmodo.com/the-iphone-5s-motion-sensors-are-totally-screwed-up-1440286727

In my own experience I often see headings off 10 degrees even after calibration (just tested a 3GS and 5 against a Brunton electronic compass and a good Suunto magnetic compass, both corrected for declination. The latter two agreed; the two iPhones were close to each other at about 8-10 degrees off. Outside on a wood surface.

Most GPS apps can also use your movement against GPS data to get accurate data for your heading, but the lameness of the internal compass makes it tough to sight a feature to use for navigation, even with augmented reality apps like Theodolite (which is very cool).

But aside from this reminder not to rely on it, I'm wondering if anyone has seen any data to indicate the error is consistent? In nautical nav you just assume everything has an error and then try to establish what it is and compensate for it, whether it be a compass or clock. I get the feeling the iOS is gonna be consistently inconsistent, but I'd love to hear different (makes me sound like Rumsfeld: I'm trying to see if it's an known unknown).

Rob
 

RobRed

Explorer
Magnetic north versus true north? Just thinking out loud. :D Software glitch I'm sure.
 
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