Compass Errors

Discussion in 'Electronics' started by Ashley Fairfield, Nov 9, 2014.

  1. Ashley Fairfield

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    I was hoping someone might have some advice on what is causing these compass errors. I have a spare compass and recently began using it due to errors on the first one. Now I am having intermittent errors on both. I can't find any loose or damaged wires but it's still possible. gpx800-803 is the old compass. 703 the new one. In .703 I can see the compass value drops to -1 just before the error appears but not on the other flights. Cheers
     

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  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Ash:
    The fact that both compasses are showing intermittent errors, given that it's a bit unlikely that both will have failed, suggests that there is some other common factor.

    Could you post some images of the copter's electronic stack, both of the central hub and the NC/GPS arrangement please?

    Are these the external compasses? Or are you having to replace the Navigation Control board in order to swap out the compass?

    Have you made any recent changes to any heavy current wiring (e.g. the Flight LiPo's), or the motor wires -- anything that might be exerting a magnetic field on the compass?

    Andy.
     
  3. Ashley Fairfield

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    Thanks for having a look Andy. I've recently had a second battery cable added for redundancy but there was a problem with the first board before that. The errors with second board only showed up since the second cable was added. P1060048.jpg P1060062.jpg P1060063.jpg P1060064.jpg
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Ash: If you use the compass on the NC board (which I presume is under the GPS), do you still get compass errors?

    Also, if you position the external compass to a different location, still errors?

    Andy
     
  5. Ashley Fairfield

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    Thanks Andy. I'll try both of those when I head out for a fly tomorrow. Cheers
     
  6. Gary Haynes

    Gary Haynes Administrator
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    Ashley most of the external compasses I have seen mounted, both MK and other brands, have the ext compass mounted on a stick sitting on a boom or the battery deck, up about 6 inches or so. Getting it away from all other sources of interference.
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Gary makes a good point -- I should have been more clear in my "different location" suggestion. I've not seen the external compass mounted on the GPS.

    Andy.
     
  8. Ashley Fairfield

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    Thanks Gary and Andy. I flew this morning without any problems with the newest of the two compass. But the fact that it is an intermittent problem means it only shows up when on a job. I'll try to get it further away from interference. Are most people using the external compass?
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    G'day Ash:

    I don't know the answer to "Are most people using the external compass?" You might want to start a Poll on this forum to ask!

    Andy.
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    I am using the external compass.
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Well, there you have it, Ash.

    The smart set are using the external compass....
    OK, the sample is somewhat limited, but work with me here.... :)

    Andy.
     

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