Compass Interference

Discussion in 'iPhone Tips, Help and Troubleshooting' started by dagomike, Jun 22, 2009.

  1. dagomike macrumors 65816

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    #1
    Is there a list of things that mess with the compass? If I point my iPhone at the Apple logo in my iMac, it flips out. Something in my car dashboard makes it nuts too.
     
  2. Muncher macrumors 65816

    Muncher

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    #2
    Well, if it operates using magnets, then it stands to reason that anything that produces a magnetic field would affect it...
     
  3. PNutts macrumors 601

    PNutts

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    #3
    Yes and yes. :D
     
  4. dmk1974 macrumors 68000

    dmk1974

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    #4
    I'll tell you, I wasn't impressed driving today while tracking on the map. That thing must be picking up a ton of interference in the car or something. The map was just randomly spinning all over the place while never locking into my direction. I was on I-290/I-355 headed south. Maybe from other cars and trucks? Nice to see where all the traffic hot spots were at least, but man, the compass part really made the map unusable!

    Tests in my office here or taking a long walk yielded perfect compass results though.
     
  5. Switz213 macrumors 6502

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    #5
    Take a REAL compass and check around. See if it's actually your iPhone or if it is just a magnetic field.
     
  6. dmk1974 macrumors 68000

    dmk1974

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    #6
    I'll try to test it again tomorrow and see. I'm just concerned how a TomTom app in the future would work (or maybe it doesn't care about the compass).
     
  7. Switz213 macrumors 6502

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    #7
    TomTom shouldn't use the compass. It should just run on GPS.
     
  8. Muncher macrumors 65816

    Muncher

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    #8
    Magnetic interference decreases with the square of the distance. Unless the sensor is lab grade equipment, the interference is coming from something close by.
     
  9. dmk1974 macrumors 68000

    dmk1974

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    #9
    Like car stereo speakers perhaps?
     
  10. Muncher macrumors 65816

    Muncher

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    #10
    That's a really good guess. I can't think of any other car parts that contain powerful magnets.

    But, the speakers are usually hidden, on the bottom of doors and such. I find it unlikely that there would be a speaker located at the same place as someone would put their phone. And, if they're using the phone, they're probably holding it, so it would be far enough from the magnets not to affect it.:confused:
     
  11. dmk1974 macrumors 68000

    dmk1974

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    #11
    The phone was probably a good 2 feet from the closest speaker, maybe 5 feet from the furthest?
     
  12. firewood macrumors 604

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    #12
    So the phone is a few feet away from the speaker magnet... and maybe a thousand miles away from the North pole. Which do you think will win?
     
  13. The General macrumors 601

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    #13
    Anything that would affect an iPhone's compass would affect a real compass, no?
     
  14. Haephestos macrumors regular

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    #14
    Check to see if it is magnetic interferance or a software bug.
     
  15. TMar macrumors 68000

    TMar

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    #15
    That was kind of the point, no?
     
  16. lovelost macrumors newbie

    lovelost

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    #16
    Welcome to the ancient world of compasses :) Compasses need regular calibration to take interference in to account, and exhibit indication errors and lag due to turning and acceleration, etc. Even Apple's own knowledge base says

    The digital compass should only be used for basic navigation assistance and should not be solely relied on to determine precise locations, proximity, distance, or direction.

    I think it's more suitable for handheld use on the street. When in the car your GPS app will provide a more useful and consistent reading.
     
  17. The General macrumors 601

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    #17
    Ah, the way I read it was "verify the iPhone's compass using a real one" ... but yeah if the real compass is also off then you know its magnetic interference and not a software problem.
     
  18. zacheryjensen macrumors 6502a

    zacheryjensen

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    May 11, 2009
    #18
    Exactly, the compass is barely useful at all and I'm really surprised they bothered adding it. In ideal conditions it can be a cool toy. Ultimately however, the GPS alone is far better for navigation purposes.

    The trick with orienting the map, when it actually works, is pretty cool though.

    In my experience, I have interference almost everywhere I go. Everywhere there is any notable amount of metal, magnetized or otherwise. I'm at a metal desk, I'm near a metal filing cabinet, I'm in the car, I'm by my wifi base station, etc. etc.

    Outside though? Works fine. And that's what counts.
     
  19. dagomike thread starter macrumors 65816

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    #19
    You would have to think someone is pretty stupid to point out a compass will be drawn to a magnetic source. A little more helpful I would think would be a discussion of where the compass isn't useful and perhaps what could be done with that.

    Holding it near anything electronic seems to mess with it. Particularly while driving it doesn't seem to work well. It doesn't seem to be the radio that's causing the problem, more the instrument cluster. Not sure how far away it needs to be, maybe a foot or two.
     
  20. Muncher macrumors 65816

    Muncher

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    #20
    Sorry :eek:. I don't have an iPhone 3GS so I can't do any field testing, but if the 3GS's compass actually has a small spinning metal piece, then it might be affected by the acceleration/deceleration of the car.

    So that's what it must be for. :D
     
  21. jazz1 macrumors 65816

    jazz1

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    #21
    I can't agree more. Today for the first time I used it with GoogleMap and I kept getting errors with some dialog box. As I was driving I really couldn't read the dialog box, but the dialog box was blocking my view of the map. Very annoying. I won't make the mistake again of using GoogleMap with the Compass feature while driving. Probably really isn't needed when your moving as you can generally see where your "dot' is headed.

    Oddly, I also kept getting the legal disclaimer coming up while this compass interference was happening. Geez! "While your reading this your likely to crash, but that is your fault not ours in any way shape or form. Just keep reading while your driving and die a horrible death" ;)

    This will certainly make me use my TomTom One Third Edition and probably drive me to the TomTom iPhone software and hardware. I guess I really didn't expect it to work that well out of the box.
     

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