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Compass Calibrate

Discussion in 'Pro/Adv Discussion' started by Slow Polk, Feb 27, 2016.

  1. Slow Polk

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    I went to a different site to fly today. The site is about 1 mile as the crow flies from my home. I got a compass calibration err. So I did the Calibration and it did not take. I tried it about 10 more times and still no calibration. I walked about 50 feet away from my car and went in 4 different directions and no calibration. When I look at the NFZ map I was close but didn't think that was the problem. So I packed up and drove about 3 miles to the high school. Same problem. But this time it was almost locking in. So up I go again to the Jr. High School. Turned everything on and no calibration required at all. The high school is also close to the NFZ. So my question is is this the way DJI is keeps us from flying in a NFZ? As a side note I drove about 10 miles away from the NFZ and again no problem. I thought from what I have read is that you could not start your motors. Not so with me. Would like to know if anyone else has had this happen to them.
     
  2. Oso

    Oso

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    To answer your question, no this is not at all the way DJI keeps us from flying in a NFZ.

    A compass error usually means that the compass is detecting a magnetic field that is too different from where it was last successfully calibrated.

    Only one mile away from the last calibration would not normally be enough to need a new calibration. Perhaps 100 or more miles away yes, but not one mile. As such, my guess is that you were just in a tough magnetic area. You didn't say if you were in an open field or not, so perhaps you were on steel reinforced concrete the first couple of tries? Something similar? If not, maybe something else was influencing the magnetic field. Underground pipes? You know, that sort of stuff.

    As you saw, once you were clear of whatever was causing the issue your Phantom then detected the magnetic field was close to prior and it did not give you an error.
     
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  3. Slow Polk

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    Thank you for getting back to me so fast. The first site was a parking lot of a wine vineyard. It was black top with no other cars for 200 yards. Not a wide open area (some trees and hills) but I have been up in areas like this before. The second site is a parking lot of our local high school. Was about 300 yards from the school and again black top pavement. The 3rd site was again another school parking lot with black top also. Of corse the 4th side was way out in the country. It is a pioneer cemetery and that was the best site of all. The dead don't use wifi.
     
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  4. Meta4

    Meta4 Moderator
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    You may have had buried pipes or cables under the asphalt - the compass was telling you it detected a magnetic influence.
    Oso is correct. The compass error is misleading.
    It doesn't mean that there is anything wrong with your compass or it's calibration and if anything, it's almost certainly not a good spot to recalibrate.
    The compass error is telling you that the compass is detecting a magnetic field significantly different from what it knows it should detect.
    You can go for months and not worry about distances 100 miles from home (possibly much more) without recalibrating the compass.

    Test for yourself to get an understanding.
    Power up your controller and Phantom without props - on the ground in a clear area - no compass error.
    Pick up the Phantom and put it on your car's roof <<Compass Error>>
    The car is a big lump of steel with a magnetic field of its own.
    Take it away and put it back on the ground away from your car and every thing's back to normal.
     
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  5. Slow Polk

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    Very interesting. So I should be able to go back to the wine vineyard and try a different spot and hopefully find a area that will work. I do thank you both so much for helping me figure this out. Thanks and enjoy the rest of your weekend.
     
  6. eaglegoaltender

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    Not saying this is your issue - however, the aggregates used as a base under asphalt (and in some cases the asphalt itself) contains gravel and waste slag from the manufacturing process of iron and steel. Even asphalt itself has recycled glass and traces of metal.

    I found this out on a job myself one day years ago now, where there was a lot of resistance when I tried to pick up one of my rare earth magnets that I had sitting on the top of an asphalt parking area. Out of curiosity I walked around with the magnet and found quite a few spots where the magnet was attracted to the asphalt surface and in some areas grabbed it pretty good, other areas there was no resistance or attraction via the magnet.

    I think dependent on how thick and/or porous the asphalt is, the metal slag which is used in the aggregate along with gravel for the base could very well impose an issue when calibrating on those surfaces.

    Ever notice the "sparkles" on the asphalt surface of a road when driving - most of the reflective surface is from the recycled glass, but some also from traces of metal slag (which is not part of the mix but some does slip through the screening process. Same thing goes for concrete slabs where you can see rust stains on the surface - metal in the mix in some areas also.
     
  7. Slow Polk

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    Interesting. I am amazed at the wealth of info one can glean from this site. I think I will try the wine vineyard again but put the drone off into the weeds. Thanks for your input.
     
  8. AMC724

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    Hold the Ac above your head when calibrating, and takeoff from your hand?

    I've never ran into a calibration problem that moving off the concrete or away from the cars didn't fix..so I don't know if this method will work,just a suggestion...

    I have taken off from hand on days with high wind gust to prevent another tip over on takeoff.


    Sent from my iPad using PhantomPilots mobile app
     
  9. Stroker

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    Try Removing your watch and any other metal that your wearing......it might help
     
  10. Slow Polk

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    Mac724 and Stroker, both good advice. Thanks for helping.