Which part tells GPS which way phone is pointing?

Question

iPhone 6s

Lanciato il 25 settembre 2015. Modello A1688/A1633. Si ripara in modo simile alle generazioni precedenti, richiede cacciaviti e strumenti di apertura. Versioni GSM o CDMA /16, 32, 64, 128 GB / Oro rosa, Oro, Argento, Grigio siderale.

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Jason @jasonthefirst

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Postato: 17 feb 2017

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Which part tells GPS which way phone is pointing?

The GPS locates me fine, but when I'm in motion, the arrow indicating my direction of travel is ALWAYS off, usually by about 30 degrees counterclockwise.

I've tried recalibrating the compass and turning location services on and off over and over again... no dice.

So I figure perhaps there's a part I can replace that would solve this problem, but I don't know which part!

Thanks!

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Just saw this and had to laugh a bit: Astonishing geomagnetic spike hit the ancient kingdom of Judah. So you can see our dependance on even the simplest mechanical compass may not even work!

17 feb 2017 da Dan

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Dan @danj

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Postato: 17 feb 2017

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Its possible the chip it bad but thats beyond what you can fix as a DIY. More likely you may have something magnetic on you or near you thats influencing the compass.

To understand whats happening here lets review how your location is known:

The GPS only shows your location longitude and latitude, it's not that precise due to the way its designed.
Your compass tells you direction but its based on magnetic north, not true north (in the northern hemisphere). So again it's not that precise.

Both have additional computations to aid them in their precision.

In the case of location, cellular towers are used as well as WiFi AP's which are static and have been identified by multiple GPS systems in their travels.
In the case of the compass, it leverages GPS to know the distance variation of magnetic north and true north so depending on your area a fudge value is modified. One of the problems we have is magnetic north is moving! Here's a bit more on this: Wandering of the Geomagnetic poles. So the fudge factor used can be off and as you get closer to the equator the factor error can be off by quite a lot.

If you are sure by using a second iPhone or other electronic GPS/Compass as a reference I would visit an Apple Store to have the phone serviced.

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Thank you for the thorough reply!

To be clear, then, it's the compass functionality that is likely causing maps apps to think I'm driving sideways?

And if this is the case, my compass app should be off compared to a real compass (or working one on another phone)?

And if my compass is misaligned, that's something to bring to Apple for a fix?

Thanks again!

17 feb 2017 da Jason

Since you are moving the ring of the area the GPS system thinks you are within can be off a bit. Here's a bit more on it: How accurate is GPS?

The position you are in relation to the map app may not be correct, hence you see your self tracking in parallel of the road not on the road!

So to be clear here running in parallel is a GPS processing error within the phone not a compass issue. Often this is do to a moisture issue messing up the timing circuit within the phone.

It will need to be serviced by Apple or Apple authorized service center.

17 feb 2017 da Dan

Ok I fear I've not been clear... the gps positioning is great. Spot on.

The issue is instead that the directional arrow--the little thing attached to the blue dot that's supposed to tell you which way you're facing--points off the side of the road.

GPS knows exactly where I am on the road, it just seems to think I'm moving down that road sideways.

So it seems the GPS chip and whatever is used to locate me is working great, it's *just* the directional arrow that's always wrong.

Does that change your calculus of what might be wrong?

17 feb 2017 da Jason

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Just saw this and had to laugh a bit: Astonishing geomagnetic spike hit the ancient kingdom of Judah. So you can see our dependance on even the simplest mechanical compass may not even work! — Dan
Thank you for the thorough reply!

To be clear, then, it's the compass functionality that is likely causing maps apps to think I'm driving sideways?

And if this is the case, my compass app should be off compared to a real compass (or working one on another phone)?

And if my compass is misaligned, that's something to bring to Apple for a fix?

Thanks again! — Jason
Since you are moving the ring of the area the GPS system thinks you are within can be off a bit. Here's a bit more on it: How accurate is GPS?

The position you are in relation to the map app may not be correct, hence you see your self tracking in parallel of the road not on the road!

So to be clear here running in parallel is a GPS processing error within the phone not a compass issue. Often this is do to a moisture issue messing up the timing circuit within the phone.

It will need to be serviced by Apple or Apple authorized service center. — Dan
Ok I fear I've not been clear... the gps positioning is great. Spot on.

The issue is instead that the directional arrow--the little thing attached to the blue dot that's supposed to tell you which way you're facing--points off the side of the road.

GPS knows exactly where I am on the road, it just seems to think I'm moving down that road sideways.

So it seems the GPS chip and whatever is used to locate me is working great, it's *just* the directional arrow that's always wrong.

Does that change your calculus of what might be wrong? — Jason

iPhone 6s

Which part tells GPS which way phone is pointing?

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