Another mangetic interference question

[Sprocket]

Is it possible to use the compass app in my Iphone to detect any magnetic interference at my takeoff point? Imagine the compass as sort of a "metal detector" to sweep the area at and around the launch point. Is there an app that does that and gives a readout in clear, easily understood results? Thanks in advance.

 

[msinger]

No external compass or app is needed to check for magnetic interference. Do this instead:

1) Find a takeoff spot that you know is not near any magnetic metal objects (e.g. rebar in concrete sidewalks).

2) Make sure your drone is never near magnetic metal objects after it has been powered on. It’s best to power on your drone in the exact location where you plan to take off.

3) Check the status message at the top of DJI GO and make sure it’s not reporting a magnetic interference error (like in the screenshot below). If you see this error, that’s a sign that your drone is near some type of magnetic metal object. Move your drone to a different location.



4) When your drone is on the ground at the takeoff spot, look at the map in DJI GO and verify that the red aircraft symbol is pointing in the same direction as the drone. If the drone and arrow are not both pointing in the same direction, that’s a sign that your drone is near some type of magnetic metal object.

5) Make sure the red aircraft symbol in DJI GO is not slowly rotating as your drone is sitting on the ground. If the red aircraft symbol is rotating, that’s a sign that your drone is near some type of magnetic metal object.

 

[sar104]

The procedure described by @msinger is the simplest and most reliable, because it directly ensures that the IMU yaw value has been correctly initialized.

But, to answer your specific question, yes - you could use your iPhone compass, or one of the iPhone magnetometer apps, to look for distortion of the earth's magnetic field. I used to do exactly that until @BudWalker proposed that simply checking orientation was more robust.