how does my iphone compass know true north without internet access?

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Level 1

5 points

how does my iphone compass know true north without internet access?

Hello,

I am getting more interested in outdoor navigation and a question came to my mind... will the compass on my iphone work without internet access?

To elaborate, I know that the gps will work even in airplane mode, i know my phone will know my geographic coordinates, however, i think that the iphone compass by default knows and points to magnetic north even without internet acess.

My guess is that when you choose in settings for your phone to show "true north" it has to access from somewhere in the internet the information about the magnetic declination of the location where i am in order to then calculate the true north.

If my guess is correct, how does the compass in my iphone remain accurate even without internet connection? does it even? how does it know the magnetic declination of a place if there is no cell signal available?

Thanks.

iPhone SE, iOS 10.3.3

Posted on Sep 17, 2017 9:23 PM

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Answer 1

Best reply

ckuan

Level 10

120,673 points

Sep 17, 2017 9:28 PM in response to staypuft001

It uses a Magnetometer

A magnetometer is built-in since the iPhone 3GS generation, which is used to measure the strength and/or direction of the magnetic field in the vicinity of the device. Sometimes certain devices or radio signals can interfere with the magnetometer requiring users to either move away from the interference or re-calibrate by moving the device in a figure 8 motion. Since the iPhone 3GS, the iPhone also features a Compass app which was unique at time of release, showing a compass that points in the direction of the magnetic field.

Important: The accuracy of the compass can be affected by magnetic or environmental interference; even the magnets in the iPhone earbuds can cause a deviation. Use the digital compass only for basic navigation assistance. Don’t rely on it to determine precise location, proximity, distance, or direction.

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Answer 2

Kappy

Level 10

361,707 points

Sep 17, 2017 9:28 PM in response to staypuft001

It can work via GPS which does not require the Internet or by cellular if it has cellular.

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