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Compass Errors

Discussion in 'General Discussion' started by RVD98072, Dec 30, 2015.

  1. RVD98072

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    The last 2 days I got compass errors when I first established a connection between the controller and aircraft. It goes away if I reboot the aircraft. This is a P3A with the latest firmware.

    I do the compass calibration before each flight and I do it here too and it seems successful but still gives an error.

    I am not near any major power lines or anything like that and this was in 2 different locations.

    The only things that I can think of are:

    1) I am taking off from a picnic table because the grass is too wet. There is some metal to the structure of the picnic table.

    2) I have my tablet case nearby and it has a magnet in it but it's small.

    Just to be safe, when I reboot, I move the aircraft a bit away from all of my gear.

    Any thoughts?
     
  2. msinger

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    What happens when you do not take off from the picnic table? If you don't see an error, then the metal in the table is probably the cause.
     
  3. RVD98072

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    Well, I only have 2 data points as of today and the only thing I can think of that was in common the last 2 days were 2 different picnic tables. The tables are mostly wood but there is some metal in the framing, etc.

    In the past, I did not get errors when I just took off from the grass or cement. I'll try taking off from the cement tomorrow.
     
  4. msinger

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    Cement is not a good idea either since it probably has rebar in it.
     
  5. Meta4

    Meta4 Moderator
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    A compass error doesn't mean that you have a problem with your compass - it means the compass has detected a problem with the magnetic field it is exposed to not matching what it expects.
    That means that you have put the Phantom down somewhere that some iron or steel is close to the compass in the bottom of one of the legs.
    Most likely you have some bolts or framework right under the Phantom.
    The problem with the "calibrate every flight" method is that it introduces the possibility of calibrating in a bad location and screwing up your compass calibration.
    If you calibrate in a distorted magnetic field, when your Phantom ascends beyond the magnetic distortion into the earth's normal magnetic field - what it thinks is north, isn't.
    You might get away with it or in a bad case the Phantom will have a real problem between the inputs from GPS and the screwy compass - and that can end up badly.

    Understand your compass and when calibration is necessary and you'll fly safer.
    Compass Calibration, A Complete Primer | DJI Phantom Forum