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  1. George Race

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    [Moderator Edit: This is information is not accurate.]

    Forgive me if I am covering material that has already been covered many times, but I have searched and can't seem to find the information that I am going to place here. DJI has stated many times that you only need to calibrate your compass if you move a good distance from where it was calibrated the last time, and it flew just great. There are other ways that have been reported, that could possibly effect compass calibration, like having it exposed to a strong magnetic field, or stored in a vehicle next to the door mounted speaker. But in reality, even those type of events should not influence the stored calibration from the last successful calibration. The Compass Calibration is stored numerically in the firmware when you do the calibration. So, if that is indeed true, the calibration location, stored in firmware, should not have any way of being changed, short of your doing a Compass Calibration and storing new variables that replace the existing ones from the last calibration.

    So if all the above is really the way it works, and I am not claiming that it is, then the simple way to know when to calibrate your compass, after the first successful calibration, is to only consider calibration when moving, as DJI has stated, to some distance from the last calibration place. In order to know where to do that, you need a Magnetic Compass Calibration Zone Map. Attached below is a Magnetic Declination Map that covers our Hemisphere.

    As long as you stay within your "numbered" area, where you did the last calibration, you should always be good to go without doing a Compass Calibration before that next flight.

    Compass_Zones.jpg
     
    #1 George Race, Apr 7, 2016
    Last edited by a moderator: Apr 9, 2016
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  2. Kman

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    DJI has always stated you only need to calibrate the compass if you fly 100 or more miles from the last location you did a compass calibration.

    This is nothing new.
     
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  3. msinger

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    While I agree this is good advice and I do this (and these things), I don't recall ever seeing DJI state a number. In their latest manuals, they are advising to calibrate "before each flight". Then again, just a few months ago, they were advising people that you can fly on at least a 50% charged battery. I guess we sometimes need to pick and choose which advice is best to follow.
     
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  4. CaptainDrone798

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    Using the map above, I have calibrated my compass once, in January 2016, in zone 11. I've never had to recalibrate as it flies perfect. Recently I went to zone 13 on the map. Didn't calibrate and the drone still flew perfectly straight.

    All of the above to say. Only calibrate if you believe it needs it.
     
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  5. snowghost

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    Yes DJI is schizophrenic in that regard. Is there a more granular map so you can see actual cities? I'd want to know if I were on a "line".

    I'm in Los Angeles and can't tell if it's 4 or 5.
     
  6. ringolong

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    Do not recalibrate before every flight!! You will increase the risk of errors.

    Only calibrate the compass when the DJI GO app or the status indicator prompt you to do so.

    When to Recalibrate

    1.When compass data is abnormal and the Aircraft Status Indicator is blinking green and yellow. 2.When ying in a new location or in a location that is different from the most recent ight. 3.When the mechanical or physical structure of the Phantom 4 has been changed.
    4.When severe drifting occurs in ight, i.e. Phantom 4 does not y in straight line.

    I would recommend reading the manual.
    https://dl.djicdn.com/downloads/phantom_4/en/Phantom_4_User_Manual_en_v1.2_160328.pdf
     
  7. msinger

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  8. ringolong

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    Wow. Now that is bad. Guess you are on your own OP lol.

    Screen Shot 2016-04-07 at 10.31.42 PM.png

    I think I would calibrate on a need to do so basis.
     
  9. msinger

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    Wow... I totally missed the above gem. It blows my mind how they could pack so much conflicting information into such a small section of the manual.
     
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  10. snowghost

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    Dude, so I move 12 feet and have to recalibrate? Nonsense. I calibrated my compass 1 year ago and never have done an IMU. However, always check the Go app for the values.
     
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  11. George Race

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    I would bet that you are good to go in BOTH 4 & 5, if you do it there!
     
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  12. Jussaguy

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    I HAVE ABSOLUTELY NO OPINION ON THIS MATTER. ;)
     
  13. Jussaguy

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    This is taken out of context, this is the method to actually calibrate not when you should.

    It clearly states WHEN it thinks you should. I am not stating anything about it though but the manual is pretty clear about when you should.
     
  14. ringolong

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    The manual states to do it every time, and it also states to not do it every time. I guess you could flip a coin to decide.

    I will just continue to do it on an as needed basis.
     
  15. Fat City

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    Local effects can cause the magnetic declination to differ from the chart. Within the same numbered region, the vector's vertical component (or inclination) depends on your distance from the pole. Bottom line is that you should re-calibrate if you want to fly far enough away from the previous calibration.

    From the Wikipedia article on magnetic declination:

    A rough estimate of the local declination (within a few degrees) can be determined from a general isogonic chart of the world or a continent, such as those illustrated above. Isogonic are also shown on aeronautical and nautical charts.

    Larger-scale local maps may indicate current local declination, often with the aid of a schematic diagram. Unless the area depicted is very small, declination may vary measurably over the extent of the map, so the data may be referred to a specific location on the map. The current rate and direction of change may also be shown, for example in arc minutes per year. The same diagram may show the angle of grid north (the direction of the map's north-south grid lines), which may differ from true north.​
     
    #15 Fat City, Apr 8, 2016
    Last edited: Apr 8, 2016
  16. John Locke

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    I don't know how the OP can arbitrarily state a magnetic map he found somewhere on the internet automatically applies to DJI drones. I'm calling BS.
     
  17. ianwood

    ianwood Taco Wrangler
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    This is incorrect information. You do not calibrate to adjust for magnetic declination. You calibrate to adjust for magnetic deviation and inclination. Please read this: Compass Calibration, A Complete Primer
     
  18. George Race

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    Ianwood" Nowhere in my comment did I say that you calibrate to adjust for Magnetic Declination!

    I did say "Attached below is a Magnetic Declination Map that covers our Hemisphere."

    Swinging the compass on any Quad-copter, is no different than swinging the compass on a ship or an airplane.
    In the case of a digital compass, you are attempting to find a compromise between finding and recording numerically, the difference between "True North" and "Magnetic North" at your current location.

    Showing the declination map for our hemisphere was simply a way of demonstrating what you are referring to when you say that you should calibrate your compass when you move a 100 miles or so. The current declination map simply shows an approximate view of when the orientation changes plus or minus 5 degrees, depending if you are moving East or West of your current location.

    The current Agonic Line, where True North and Magnetic North are about the same, is the line on the chart that is from the Eastern tip of Louisiana up past the far western tip of Wisconsin.

    So, please tell me where we are in disagreement, and why my information is not accurate.
     
  19. ianwood

    ianwood Taco Wrangler
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    Here:

    That is not good advice. Depending on your direction of travel, you can go for thousands of miles without crossing a declination boundary. Should you calibrate in that scenario. Absolutely. Why? Because magnetic deviation and inclination could be entirely different.

    If you fly in a mountainous area and then drive 20 miles to a prairie, should you recalibrate? Yes. Why? Because it is probable that the magnetic deviation has significantly changed from semi-ferrous geological mountain rock to a much more neutral area with very different deviation properties. The so called soft iron effect.
     
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  20. George Race

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    As this whole posting, according to you, is misrepresenting of DJI compass calibration techniques, who do I talk to to have the complete posting removed from this forum? Sure don't want others using bad information!