[TowerTalk] How accurate are iPhone Compass apps?

[Kevin Normoyle]

Iphone uses AKM AK8975 chip to sense the earth's magnetic field (four Hall 
effect sensors on a chip)
so GPS isn't providing compass. I would think it's pretty accurate. Sure there's 
software and calibration, and the possibility for error, but I would imagine 
it's really good. I have a Garmin gps/compass that senses magnetic field for 
it's compass similarly.

-kevin
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