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MAG INTERF.

vita55

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tried flying my pro for 1st time today. I was in field with plenty of space around. All we well until I tried to lift off and the controller indicated I had MAG interference issue. Any suggestions? I'm new to this and cannot find out much about this other than near metal objects which is not the case here. Any help is greatly appreciated.
 

Dronason

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Did you recalibrate the compass when you get your new drone?
In most case it can fly but it is highly recommended to recalibrate everything at your location.
 
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niki

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Did you checked the magnetic storm wheadercast for the location? Sometimes the storms are lasting only about 1 hour even less.

If you callibrate the compass at a time of magnettic storm you may have compass problems on the following flights.

Sometimes there are very short magnetic anomalies but this is very very rare.

If the wheathercast was clear of any storms when you got the error then first try flying on another place and see if there are any issues and if there are then try to calibrate compass.

Most of the fly aways are mainly caused by wrongly calibrated compass. At the wrong time when there was magnetic storm at the time of callibrating or the place having big metal objects (structures), electric poles or bridges, also they could be under the ground (not visible)

Personally I never ever have done compass callibration on our I1 RAW, flying with it from 3 years and we travel sometimes 700+ km (it is recomended when you travel more than 400km of initial callibration to make a fresh one)
tried flying my pro for 1st time today. I was in field with plenty of space around. All we well until I tried to lift off and the controller indicated I had MAG interference issue. Any suggestions? I'm new to this and cannot find out much about this other than near metal objects which is not the case here. Any help is greatly appreciated.
 
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sar104

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Neither of the replies above are correct.

Firstly, you should not need to recalibrate the compass unless the app instructs you to do so. Secondly, magnetic storms, despite the name, have no effect on the earth's magnetic field, and will not affect the compass performance.

You need to be a bit more specific about what happened. The controller reported magnetic interference - not the app? Then what happened? Did the aircraft fly okay, or were there control issues? I suggest that you retrieve the mobile device DAT file and post it here - that should definitively show what was happening.

How to retrieve a V3.DAT from the tablet
 

Dronason

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Neither of the replies above are correct.

Firstly, you should not need to recalibrate the compass unless the app instructs you to do so. Secondly, magnetic storms, despite the name, have no effect on the earth's magnetic field, and will not affect the compass performance.

You need to be a bit more specific about what happened. The controller reported magnetic interference - not the app? Then what happened? Did the aircraft fly okay, or were there control issues? I suggest that you retrieve the mobile device DAT file and post it here - that should definitively show what was happening.

How to retrieve a V3.DAT from the tablet
I don't mean to recalibrate before each flight but for a new drone it is better to make a good calibration (out of magnetic distortion) apart if you leave beside the DJI factory.
In my case I made the error to calibrate where there was metallic stuff in the ground. After calibration, app says all good but as soon I lift it up then it was free of magnetic interference and goes crazy. With Phantom3 and Go app, it was the magnetic field that was displayed and it was easier to interpret it. Now it is an indicator value, at least with the Mavic, there are 2 compas now and if they don't give the same indication, that's not a good sign at all.

Fully agree with you regarding the .DAT file.
 
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genesimmons

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i have got the mag interfiernce warning a few times, once when i launched off a cement picnic table and once when i launched off the tail gate of my truck and once when i launched at a boat launch, not sure what triggers the warning, the boat launch warning actually affected my flight
 

niki

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Neither of the replies above are correct.

..... Secondly, magnetic storms, despite the name, have no effect on the earth's magnetic field, and will not affect the compass performance. ...

Actually you are totally wrong :) Where did you learn that, do you have a pilot license?

Got this from wikipedia but that doesn't mean I know it from there :)

"Several space weather phenomena tend to be associated with or are caused by a geomagnetic storm. These include solar energetic particle (SEP) events, geomagnetically induced currents (GIC), ionospheric disturbances that cause radio and radar scintillation, disruption of navigation by magnetic compass and auroral displays at much lower latitudes than normal."

Geomagnetic storm - Wikipedia
 
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Thwyllo

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Apart from the obviously man-made infrastructure, what's naturally below the ground can have a big effect, often causing significant compass deviations or even rendering a compass unreadable. Iron ore deposits, dolerite and especially many kinds of volcanic rock are particularly disruptive.

Haven't looked at this in detail so don't know how localised it is..?

Magnetic anomaly map of North America with detailed aeromagnetic surveys
 
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rcaf

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Cell phones or other devices that transmit (like bluetooth fitness monitors, etc.) will cause this. Is your cell phone running a GPS app or other monitoring app like weather? Get rid of all electronics on your body and try again.
 

sar104

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Actually you are totally wrong :) Where did you learn that, do you have a pilot license?

Got this from wikipedia but that doesn't mean I know it from there :)

"Several space weather phenomena tend to be associated with or are caused by a geomagnetic storm. These include solar energetic particle (SEP) events, geomagnetically induced currents (GIC), ionospheric disturbances that cause radio and radar scintillation, disruption of navigation by magnetic compass and auroral displays at much lower latitudes than normal."

Geomagnetic storm - Wikipedia

The earth's magnetic field at the surface is of the order of 50 µT, with normal fluctuations measured in a few tens of nT. Extreme geomagnetic storms (Kp ≥ 9) produce variations of less than 500 nT, i.e. two orders of magnitude less than the field strength. Do you have any documented examples of geomagnetic storms affecting magnetic compasses?
 

Dronason

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Cell phones or other devices that transmit (like bluetooth fitness monitors, etc.) will cause this. Is your cell phone running a GPS app or other monitoring app like weather? Get rid of all electronics on your body and try again.
That don't sound like a transmission issue, the drone compass detect disturbance when going up in the air (goes away from the pilot).
 

niki

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The earth's magnetic field at the surface is of the order of 50 µT, with normal fluctuations measured in a few tens of nT. Extreme geomagnetic storms (Kp ≥ 9) produce variations of less than 500 nT, i.e. two orders of magnitude less than the field strength. Do you have any documented examples of geomagnetic storms affecting magnetic compasses?

INFLUENCE OF MAGNETIC STORMS ON COMPASS
http://www.viviss.si/download/viviss/ZBORNIK MGB/Sadovski_paper_11_20.pdf

In the conclusion you can read:
"During his everyday work a navigator must necessarily take into consideration the weather and climate conditions. Such conditions are under the direct influence of geomagnetic storms. Today it is possible to forecast the appearance of a geomagnetic storm. This means that errors in navigation devices caused by such storms may also be predicted and that they may be managed systematically..."

and

"... For Extreme Magnetic Storm the indicated K-index was 10+. This index is directly related to the maximum amount of fluctuation (relative to a quiet day) in the geomagnetic field over a three-hour interval. This index indicates also the error of compass in indication of direction..."

So the K index is actually showing the level of compass error :)
 

sar104

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INFLUENCE OF MAGNETIC STORMS ON COMPASS
http://www.viviss.si/download/viviss/ZBORNIK MGB/Sadovski_paper_11_20.pdf

In the conclusion you can read:
"During his everyday work a navigator must necessarily take into consideration the weather and climate conditions. Such conditions are under the direct influence of geomagnetic storms. Today it is possible to forecast the appearance of a geomagnetic storm. This means that errors in navigation devices caused by such storms may also be predicted and that they may be managed systematically..."

and

"... For Extreme Magnetic Storm the indicated K-index was 10+. This index is directly related to the maximum amount of fluctuation (relative to a quiet day) in the geomagnetic field over a three-hour interval. This index indicates also the error of compass in indication of direction..."

So the K index is actually showing the level of compass error :)

That's not what I asked. There is no estimate of compass effect magnitude in that paper, and the numerical values quoted for the field strengths are completely consistent with what I posted above. So, again, do you know of any documented examples of geomagnetic storms affecting compass navigation? Suppose we lower the bar even further - do you even know of any anecdotal reports of that happening?
 

niki

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That's not what I asked. There is no estimate of compass effect magnitude in that paper, and the numerical values quoted for the field strengths are completely consistent with what I posted above. So, again, do you know of any documented examples of geomagnetic storms affecting compass navigation? Suppose we lower the bar even further - do you even know of any anecdotal reports of that happening?

Did you read the whole 20 pages including all the references on the back for only 3 minutes including the time for writing the new post? I'm asking because you posted a reply only 3 minutes after my post? If you read the whole paper then you can estimate it on your own :) And actually you didn't posted any scientific data supporting your statement. There are many recorded history events with compass anomalies during solar storms, one can do a search on the net.

Also I have first hand experience in flying in magnetic storms and I know what can happen. Can you guess...? Compass error in mid flight and the drone switching to atti mode, and that was happening only when flying in magnetic storm, not always but it was happening a few times so a pilot must be aware of that while planning his flight.

And a few more records describing compass variations caused by geomagnetic storms:

BBC NEWS | Science/Nature | Earth buffeted by big solar flare
The compass variation at the Lerwick geomagnetic observatory in Scotland changed by 5.1 degrees in only 25 minutes at about 0630 GMT

Space Weather Newspaper Archives
November 18, 1882 - The Transit of Venus Storm - It produced a compass bearing deflection of nearly 2 degrees
 

BudWalker

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.....
In my case I made the error to calibrate where there was metallic stuff in the ground. After calibration, app says all good but as soon I lift it up then it was free of magnetic interference and goes crazy. With Phantom3 and Go app, it was the magnetic field that was displayed and it was easier to interpret it. Now it is an indicator value, at least with the Mavic, there are 2 compas now and if they don't give the same indication, that's not a good sign at all.
....
I suspect what actually happened here was the calibration was valid. If there were enough geomagnetic distortion to affect the calibration then the calibration attempt would have been rejected with a "move to a new location" message being issued. Generally speaking, geomagnetic distortions caused by pipes, rebar, etc in the ground only extend a meter at most above the ground.The calibration dance occurs above that geomagnetic distortion.

The incident was probably caused when the AC was placed on the ground where the geomagnetic distortion caused the Yaw to be initialized incorrectly due to the incorrect compass value.
 

sar104

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Did you read the whole 20 pages including all the references on the back for only 3 minutes including the time for writing the new post? I'm asking because you posted a reply only 3 minutes after my post? If you read the whole paper then you can estimate it on your own :) And actually you didn't posted any scientific data supporting your statement. There are many recorded history events with compass anomalies during solar storms, one can do a search on the net.

Also I have first hand experience in flying in magnetic storms and I know what can happen. Can you guess...? Compass error in mid flight and the drone switching to atti mode, and that was happening only when flying in magnetic storm, not always but it was happening a few times so a pilot must be aware of that while planning his flight.

And a few more records describing compass variations caused by geomagnetic storms:

BBC NEWS | Science/Nature | Earth buffeted by big solar flare
The compass variation at the Lerwick geomagnetic observatory in Scotland changed by 5.1 degrees in only 25 minutes at about 0630 GMT

Space Weather Newspaper Archives
November 18, 1882 - The Transit of Venus Storm - It produced a compass bearing deflection of nearly 2 degrees

Or, as you might have guessed, I was already familiar with that paper - which also accounts for why I knew that the magnetic field strength values that it quoted agreed with mine.

The Lerwick measurement of 5.1° in 2003 is interesting, although that was a massive disturbance and the observatory is pretty far north. 5.1° is not enough to upset the FC in a DJI aircraft though. The 1882 event is also interesting, but 2° is within the error bounds of most magnetic compasses. In any case, still no records of disturbance of navigational compasses? Do you not think that there would be records if such events actually happened? Your assertion that this affects compass navigation is not supported.

Your assertion that it can affect compass calibration completely misunderstands the purpose of the calibration, which has nothing at all to do with the external magnetic field - the calibration is to subtract out the magnetic field of the aircraft. It doesn't matter what the external field is as long as it is constant for the duration of the calibration. And even if it isn't constant, variations at least two orders of magnitude less than the earth's field will have no measurable effect on calibration.

As another way of looking at it quantitatively, and using the values from the Sadovski et al. paper that you quoted, if an externally-induced field of 500 nT were introduced, worst-case, i.e. orthogonal to the earth's existing field of around 50 µT, then the change in apparent magnetic north would be approximately 0.01 rad, or 0.6°. That's going to be completely undetectable with any kind of navigational magnetometer.
 

InvisibleName

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Or, as you might have guessed, I was already familiar with that paper - which also accounts for why I knew that the magnetic field strength values that it quoted agreed with mine.

The Lerwick measurement of 5.1° in 2003 is interesting, although that was a massive disturbance and the observatory is pretty far north. 5.1° is not enough to upset the FC in a DJI aircraft though. The 1882 event is also interesting, but 2° is within the error bounds of most magnetic compasses. In any case, still no records of disturbance of navigational compasses? Do you not think that there would be records if such events actually happened? Your assertion that this affects compass navigation is not supported.

Your assertion that it can affect compass calibration completely misunderstands the purpose of the calibration, which has nothing at all to do with the external magnetic field - the calibration is to subtract out the magnetic field of the aircraft. It doesn't matter what the external field is as long as it is constant for the duration of the calibration. And even if it isn't constant, variations at least two orders of magnitude less than the earth's field will have no measurable effect on calibration.

As another way of looking at it quantitatively, and using the values from the Sadovski et al. paper that you quoted, if an externally-induced field of 500 nT were introduced, worst-case, i.e. orthogonal to the earth's existing field of around 50 µT, then the change in apparent magnetic north would be approximately 0.01 rad, or 0.6°. That's going to be completely undetectable with any kind of navigational magnetometer.
Ouch! My head hurts! And I only read your words, not the posted paper!! Hope you guy’s can resolve your differences and then post a summary.... in English! :)
 

daasmangi

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I don't mean to recalibrate before each flight but for a new drone it is better to make a good calibration (out of magnetic distortion) apart if you leave beside the DJI factory.
In my case I made the error to calibrate where there was metallic stuff in the ground. After calibration, app says all good but as soon I lift it up then it was free of magnetic interference and goes crazy. With Phantom3 and Go app, it was the magnetic field that was displayed and it was easier to interpret it. Now it is an indicator value, at least with the Mavic, there are 2 compas now and if they don't give the same indication, that's not a good sign at all.

Fully agree with you regarding the .DAT file.

With my Mavic Pro I can take off from the hood of my car but my Phantom is way too sensitive around any metallic object even my car.. so I’m thinking it could be something metallic underground. Try moving 50 meters and try again
Cheers
Daasmangi
 

sar104

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Ouch! My head hurts! And I only read your words, not the posted paper!! Hope you guy’s can resolve your differences and then post a summary.... in English! :)

Sorry about that. I was trying to keep the discussion quantitative to illustrate that there is no evidence (that I have found) of anyone reporting severe enough geomagnetic storm effects to measurably affect navigational compasses. @niki has correctly noted that geomagnetic storms do, rather obviously, affect the earth's magnetic field but does not seem to have found any evidence of effects large enough to matter. I've never heard of such occurrences being reported, and I couldn't find any either when I searched.
 
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