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Professional Raw Compass Numbers Out of Range?

Discussion in 'Phantom 3 Help' started by DroneTone, Jan 10, 2016.

  1. DroneTone

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    I'm concerned that my raw Compass Calibration numbers may be out of whack.
    Specifically the X and Z numbers, the Y and Mod values seem within range.
    I'm assuming normal number ranges for X, Y and Z are: + or - 300
    Compass Mod range: 1400-1800
    I know that Mod = square root of (X*X+Y*Y+Z*Z).

    First a bit of preface: Phantom 3 Professional, Firmware v1.6.0040, using an Pad Air DJI GO app v2.4.3.
    I have successfully done several cold IMU re-calibrations and gimbal re-calibrations on level surfaces, indoors.
    I have successfully done numerous compass calibrations outdoors in grassy open fields or baseball diamonds in different locations on different days.
    During compass calibrations I do stay away from concrete rebar, buildings, any other metal and take all metal objects off my person such as keys, cellphone and spare change.

    I do not get any messages from the Phantom saying anything is wrong with the compass or any other problem.
    I usually fly in P-GPS mode with no issues, it holds a selected altitude well with only small wind corrections.
    My longest distance has been about 3/4 mile away and 390 ft. altitude.
    I can easily get the phantom into a stable hover slightly above me for hand-catching or hover into a soft landing.
    The Phantom does not exhibit any "TBE" or toilet bowl effect or wavering during a hover.

    X Y Z Mod
    Initial Compass -516.00 275.00 1401.00 1518.12
    Calibration #1 -516.00 272.00 1387.00 1504.66
    Calibration #2 -512.00 313.00 1367.00 1492.92
    Calibration #3 -518.00 316.00 1363.00 1491.96
    Calibration #4 -526.00 322.00 1359.00 1492.39
    Calibration #5 -523.00 250.00 1375.00 1492.20
    Calibration #6 -534.00 154.00 1383.00 1490.49

    So basically the P3P seems to fly okay, but I'm concerned these compass numbers could be the sign of
    a more serious compass error and the potential for a fly-away in the future.

    Doing numerous compass calibrations does not seem to be able to bring these numbers back into range.
    The only reason I can think of that would cause the abnormal readings is that during several initial flights I did use my Apple case for the iPad as a launch pad for protection from some tall or wet grass.
    I had forgotten the Apple case has two segments on the top cover which are magnetic.
    I am wondering if the case cover lying underneath the Phantom could have magnetized the compass in the legs.

    How can these raw compass numbers be brought back into range?
    Continue to repeatedly do compass calibrations?
    Is a degaussing needed? Should a Phantom 3 be degaussed?
    If so, is the procedure the same as the one in the YouTube video for degaussing the Phantom 2?

    In addition, it may be related or not, in the GO app, lower left screen Flight Telemetry, the red arrow pointer does not exactly agree with where the Phantom is pointed. Sometimes the red arrow points about 20-30° to the left of where the Phantom is pointed (on the ground and in the air). Calibrations have seemed to gotten it more accurate, the red arrow now points about 5° too far to the left, which is acceptable for the moment.

    Any help is appreciated-
    Thanks
     

    Attached Files:

  2. BudWalker

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    These numbers are fine. In fact they look great. There is no constraint about X, Y, and Z being [-300, 300]
     
  3. DroneTone

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    Thanks BudWalker- Nice to know.
    Any thoughts on keeping the GO app telemetry red arrow in agreement with how the Phantom is actually pointed?
     
  4. BudWalker

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    I think I've seen @msinger answer this one. Maybe he has a ready answer.
     
  5. Meta4

    Meta4 Moderator
    Staff Member

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    Two compasses are involved ... One shows which way your Phantom is pointing and another tells your tablet which way it is pointing.
    Have you ever calibrated your tablet's compass?
    Google will show you how to.
     
  6. msinger

    Approved Vendor

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    This usually means the compass needs to be calibrated on your mobile device. Try this:

     
  7. Liamus27

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    Bumping on old (ish) thread but want to understand more about these raw compass values - what they mean and how I can use them. Please can someone help or point me in the right direction?