Magnetic Interference

[snarkangel]

Airdata Link

Hello,

Ever since I moved from WA to AK, I've noticed many more "Magnetic Interference" errors and "Compass Error. Exited GPS Mode."

It's killing me, and I can't figure out why or how to fix it. I've tried calibrating the IMU and the Compass. At this point, I'm wondering if there is a problem with my location (ACTUAL magnetic interference?)

Dan

 

[sar104]

The log file is suggestive of magnetic interference at the takeoff location. The DAT file (FLY066.DAT) should shed more light on that.

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[snarkangel]

Here it is.

Thanks!

 

[sar104]

The explanation here isn't completely obvious, but it doesn't appear to be a magnetically distorted takeoff location. There is significant disagreement between the compass and IMU during the flight, but the offset is not consistent:



Looking at the magnetic modulus, there is a clear dependence on yaw, which shouldn't be the case - the modulus should be constant:



That suggests to me that the compass needs to be calibrated. If you have already done that and it hasn't fixed the issue (although I'd expect it to with those modulus variations) then it's possible that something on the aircraft is sufficiently magnetized that it is outside the range that can be calibrated, requiring demagnetization.

 

[BudWalker]

The explanation here isn't completely obvious, but it doesn't appear to be a magnetically distorted takeoff location. There is significant disagreement between the compass and IMU during the flight, but the offset is not consistent:

View attachment 82492

Looking at the magnetic modulus, there is a clear dependence on yaw, which shouldn't be the case - the modulus should be constant:

View attachment 82493

That suggests to me that the compass needs to be calibrated. If you have already done that and it hasn't fixed the issue (although I'd expect it to with those modulus variations) then it's possible that something on the aircraft is sufficiently magnetized that it is outside the range that can be calibrated, requiring demagnetization.

@snarkangel it does seem that the compass has a problem in the Yaw range [10-80] and really pronounced in [45-70]. gpsVelE-VelE (black trace) should be 0.0. The colored background is where there is an IMU error (pink - GPS_YAW_ERROR, light green - SPEED_LARGE_ERROR).



You might want to try an experiment. Do a flight facing only west. Shouldn't see any problems.

Does your MP have a tracker that isn't attached when you do the compass calibration?

 

[snarkangel]

That suggests to me that the compass needs to be calibrated. If you have already done that and it hasn't fixed the issue (although I'd expect it to with those modulus variations) then it's possible that something on the aircraft is sufficiently magnetized that it is outside the range that can be calibrated, requiring demagnetization.

I'll try again. Maybe I'm calibrating it wrong, or not well enough?

You might want to try an experiment. Do a flight facing only west. Shouldn't see any problems.

Does your MP have a tracker that isn't attached when you do the compass calibration?

No. It's completely naked and using only OEM parts (rotors, batteries, etc)

I'll try flying facing west at some point.

 

[berisen]

I had similar issues with exactly the same errors and in my case it appears to be caused by a magnetically interfered calibration site. As soon as I took it to another place which was further away from any possible objects that could interfere and re-calibrated, the errors was gone. Have been flying quite a lot since then and all the flights since then has been all "error free".

Not saying that it's the same issue at all but it might be a good idea to try and re-calibrate in another place.

 

[Flycaster]

Make sure your not wearing anything that could influence/effect the compasses...