Magnetic interference & obstacle avoidance issues

Chamanea · Jul 26, 2019

Hi there, I had an issue yesterday flying nearby a photovoltaic solar farm.

On turning on the Mavic, I very quickly got the message "Magnetic interference" (or something close) displayed on the remote. I thought this would be fixed by calibrating the compass - although not 100% sure that these 2 are linked and that it could fix my issue. But I'm used to calibrating the compass on each location change, so that's what I did.
After 1st calibration, still some interference shown, so I did a second one, and then not more interference message (if I remember well)

I then started flying around the farm, photos, video, all good. But then quite suddently, I started to get some obstacle avoidance messages and braking, while being in open air without any obstacle nor birds nor anything. This actually became worse to the point of having to fly sideways to be able to move back.
I then disabled the sensors in the DJI GO menu and the bird flew ok. However, I couldn't use any of the smart functions, such as point of interest, nor dronedeploy, as all do seem to re-activate the sensors...
I ended up in a situation where the Mavic wouldn't move at all, even after pressing go home, which I can understand if it detected (fake) obstacles all around....

Anyway, to cut a long story short, I'd like to know if potential magnetic interference could be creating these obstacle avoidance issues? have anyone experience similar issues?
I would like to (try to) understand with logs, can anyone point me on how to retreive logs for this flight?

Thanks

Mossiback · Jul 26, 2019

Chamanea said:
...Anyway, to cut a long story short, I'd like to know if potential magnetic interference could be creating these obstacle avoidance issues?

Most likely, it was the sun reflecting off of all those surfaces on the solar farm that caused the OA problems. A low sun or sun reflected off water will do the same thing. I would be careful calibrating the compass to an area that was causing the magnetic interference message. The problem comes from calibrating to the launch area that caused the error and then flying up away from the cause of the interference where the compass will read differently than at launch. It is better to launch away from the cause of the interference.

Chamanea · Jul 26, 2019

Mossiback said:
Most likely, it was the sun reflecting off of all those surfaces on the solar farm that caused the OA problems. A low sun or sun reflected off water will do the same thing. I would be careful calibrating the compass to an area that was causing the magnetic interference message. The problem comes from calibrating to the launch area that caused the error and then flying up away from the cause of the interference where the compass will read differently than at launch. It is better to launch away from the cause of the interference.

Yes it was a very sunny day and it's true that these OA issues were located more on the side where the sun would possibly reflect on the panels... Although the last problem I had was at 70m quite far away from the panels, so I suspect they wouldn't have much incidence in that case.

Chamanea · Jul 30, 2019

Does anyone know whether it's possible to deactivate the OA in smart shots such as POI, or in third party apps such as DroneDeploy ? It seems like they automatically re-activate OA sensors even though I had turned them off in DJI GO 4...

Edit: there seems to be some settings within Dronedeploy to enbale/disable OA... but the question remains for DJI GO 4 POI

Meta4 · Jul 30, 2019

Chamanea said:
On turning on the Mavic, I very quickly got the message "Magnetic interference" (or something close) displayed on the remote. I thought this would be fixed by calibrating the compass - although not 100% sure that these 2 are linked and that it could fix my issue. But I'm used to calibrating the compass on each location change, so that's what I did.
After 1st calibration, still some interference shown, so I did a second one, and then not more interference message (if I remember well)

The magnetic interference warning was your compass telling you that you chose a bad launch spot, too close to steel objects.
Recalibrating the compass does nothing at all to fix the issue your compass was warning you about.
Moving away from the problem is the correct action.

Chamanea said:
Does anyone know whether it's possible to deactivate the OA in smart shots such as POI, or in third party apps such as DroneDeploy ? It seems like they automatically re-activate OA sensors even though I had turned them off in DJI GO 4...

Edit: there seems to be some settings within Dronedeploy to enbale/disable OA... but the question remains for DJI GO 4 POI

You can disable OA in DJI Go4

Thomas B · Jul 30, 2019

Meta4 said:
The magnetic interference warning was your compass telling you that you chose a bad launch spot, too close to steel objects.
Recalibrating the compass does nothing at all to fix the issue your compass was warning you about.
Moving away from the problem is the correct action.

You can disable OA in DJI Go4

@Meta4 is spot on!
I’d add that all the electricity generation also created a huge local electromagnetic disturbance.

Chamanea · Jul 30, 2019

Meta4 said:
The magnetic interference warning was your compass telling you that you chose a bad launch spot, too close to steel objects.
Recalibrating the compass does nothing at all to fix the issue your compass was warning you about.
Moving away from the problem is the correct action.

You can disable OA in DJI Go4

Thanks for your reply. Yes I now understand that the magnetic interference had nothing to do with my OA problems, and will calibrate my Mavic further away next time I'm close to a solar farm (generating high electricity, thus magnetic field)

On the possibility to disable OA, I'm pretty sure I had this setting off (OA disabled) when I did the POI, but it seems to me that the POI will anyway use OA sensors independently from this setting. Please correct me if I'm wrong.

Chamanea · Jul 30, 2019

Thomas B said:
@Meta4 is spot on!
I’d add that all the electricity generation also created a huge local electromagnetic disturbance.

Yes, understood, thanks

Meta4 · Jul 30, 2019

Chamanea said:
Thanks for your reply. Yes I now understand that the magnetic interference had nothing to do with my OA problems, and will calibrate my Mavic further away next time I'm close to a solar farm (generating high electricity, thus magnetic field)

You are wasting your time recalibrating the compass.
It's much better to understand what it actually does rather than just doing it as a superstitious ritual.

Chamanea said:
On the possibility to disable OA, I'm pretty sure I had this setting off (OA disabled) when I did the POI, but it seems to me that the POI will anyway use OA sensors independently from this setting. Please correct me if I'm wrong.

If you turn the sensors off, they are off.

Mossiback · Jul 30, 2019

Meta4 said:
...If you turn the sensors off, they are off.

I found that Spotlight mode turns them back on on my MP.

Chamanea · Jul 30, 2019

Meta4 said:
You are wasting your time recalibrating the compass.
It's much better to understand what it actually does rather than just doing it as a superstitious ritual.

Thanks for the tips. I only recalibrate the compass when I change of spot, although I do it for every new spot not really knowing, it's true, how much distance difference between 2 spots would require that to be done. But I sware that the spiritual dance I'm doing around my Mavic has nothing to do with the compass dance - just talking to Gods