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Check App Interf Mag Message!

Arthuar

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It's appeared the "famous" wrong error.
The story.
It has been more than one month I didn't fly with my MP2.
Started it with samsung s8 Pie as usual ( never errors before) and the message appeared immediately after started the rc, and DJI GO 4.
Taken more tests more just to get a chance to solve it but neither its' been good...
The aircraft is always able to connect in opti atti etc without prob, and states Ready To Fly even!
Then I tried the same with an iPad air.And I got away with it, in a very small fly around my garden.
So, was guessing it was software it would be a good idea go for an update with dji Assistant 2 with april firmware.
Updated correctly, installed from scratch the DJIGO 4 again..nothing, same issue.
This time, the problem has got with the ipad even.

Any suggestion? recompass..change location..change connecting wires..I dont' know
I have any intention to send this to the store, right now.
 
There are lots of threads on this board that discuss magnetic interference. Invariably, it seems to me that the best recommended course of action is to change location (do not calibrate) and make sure it is an area that is far from metallic objects, including any concrete that may be reinforced with steel re-bar. And also be sure that aren't transmission towers around or high-voltage power lines.

If you go a couple of miles away to a field that is clear of all objects and potential sources of interference, and you find that the errors do NOT pop up, then you know there is something about your first location (mentioned above). If you still get the error when you have gone to a location known to be free and clear of magnetic influence / interference, then you need to worry about getting your craft looked at by service.

Chris
 
It's appeared the "famous" wrong error.
The story.
It has been more than one month I didn't fly with my MP2.
Started it with samsung s8 Pie as usual ( never errors before) and the message appeared immediately after started the rc, and DJI GO 4.
Taken more tests more just to get a chance to solve it but neither its' been good...
The aircraft is always able to connect in opti atti etc without prob, and states Ready To Fly even!
Then I tried the same with an iPad air.And I got away with it, in a very small fly around my garden.
So, was guessing it was software it would be a good idea go for an update with dji Assistant 2 with april firmware.
Updated correctly, installed from scratch the DJIGO 4 again..nothing, same issue.
This time, the problem has got with the ipad even.

Any suggestion? recompass..change location..change connecting wires..I dont' know
I have any intention to send this to the store, right now.

The Mavic 2 firmware will request compass calibration every 30 days or if the aircraft is more than 50 km from its last flight. It doesn't mean that there is anything wrong, or that there is any magnetic interference, but it won't let you fly until you recalibrate.
 
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The Mavic 2 firmware will request compass calibration every 30 days or if the aircraft is more than 50 km from its last flight. It doesn't mean that there is anything wrong, or that there is any magnetic interference, but it won't let you fly until you recalibrate.

I was under the impression, from reading various posts, that the newer DJI drones (Mavic 2 included) now have lookup tables to account for changes in significant distance and ultimately magnetic variation?

OP - I’ve dealt with this issue in the past and still do see it at random. I’ve gotten mag interference even when flying from a baseball field but oddly enough, restarting the M2P solves it. I’ve calibrated once and haven’t calibrated again and have flown just fine from random places +/- 50-75 miles in distance.

I’ve also checked my real-time sensor values for the compass to see the level of magnetic interference (green, yellow, red, with an actual visual indicator) and even though I’ve seen the magnetic interference warning on the controller, the sensor data shows 2-4% interference and all green. Weird issue at times for sure.
 
There are lots of threads on this board that discuss magnetic interference. Invariably, it seems to me that the best recommended course of action is to change location (do not calibrate) and make sure it is an area that is far from metallic objects, including any concrete that may be reinforced with steel re-bar. And also be sure that aren't transmission towers around or high-voltage power lines.

If you go a couple of miles away to a field that is clear of all objects and potential sources of interference, and you find that the errors do NOT pop up, then you know there is something about your first location (mentioned above). If you still get the error when you have gone to a location known to be free and clear of magnetic influence / interference, then you need to worry about getting your craft looked at by service.

Chris
I've also found if you are shooting near a car that is running, especially big SUVs, you really need to turn the engine off!
 
First of all thanks to all replies.
Never been close a carpet, cars, just on the sand, in the middle of a field.
Nevertheless, I will move to test few miles away, recalibrate and start again.
I can't say more, sorry :rolleyes:
 
I was under the impression, from reading various posts, that the newer DJI drones (Mavic 2 included) now have lookup tables to account for changes in significant distance and ultimately magnetic variation?

All DJI drones since the Phantom 2 have had global magnetic field models to calculate inclination and declination as a function of location. That's essential, since while inclination (angle between the magnetic field vector and horizontal - an absolute direction) can be measured, declination (angle between magnetic field vector and true north - an arbitrary direction) can never be measured.

OP - I’ve dealt with this issue in the past and still do see it at random. I’ve gotten mag interference even when flying from a baseball field but oddly enough, restarting the M2P solves it. I’ve calibrated once and haven’t calibrated again and have flown just fine from random places +/- 50-75 miles in distance.

I’ve also checked my real-time sensor values for the compass to see the level of magnetic interference (green, yellow, red, with an actual visual indicator) and even though I’ve seen the magnetic interference warning on the controller, the sensor data shows 2-4% interference and all green. Weird issue at times for sure.

That interference message is the time/distance recalibration request, which is why there is no actual interference being measured. It's not supposed to go away just because you restart the aircraft. It would be interesting to see the DAT file event stream to see why that is happening.
 
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All DJI drones since the Phantom 2 have had global magnetic field models to calculate inclination and declination as a function of location. That's essential, since while inclination (angle between the magnetic field vector and horizontal - an absolute direction) can be measured, declination (angle between magnetic field vector and true north - and arbitrary direction) can never be measured.



That interference message is the time/distance recalibration request, which is why there is no actual interference being measured. It's not supposed to go away just because you restart the aircraft. It would be interesting to see the DAT file event stream to see why that is happening.
Well, if it was easy, it would be a interesting way about learning something new.
Can you show me, How I can get that kind of file..or maybe I can' t handle that?
 
The Mavic 2 firmware will request compass calibration every 30 days or if the aircraft is more than 50 km from its last flight. It doesn't mean that there is anything wrong, or that there is any magnetic interference, but it won't let you fly until you recalibrate.

I've got a couple of spots over 50 km from home where I often fly. Every time I get there, I usually have to re-calibrate... When I get back home I have to re-calibrate again.

It's a pain, but I guess DJI knows what they're doing.
 
I've got a couple of spots over 50 km from home where I often fly. Every time I get there, I usually have to re-calibrate... When I get back home I have to re-calibrate again.

It's a pain, but I guess DJI knows what they're doing.

They may or may not know what they are doing - there is no good technical reason to recalibrate just because you change location. Calibrating every 30 days might be useful in case the magnetic field of the aircraft has changed. Either way the implementation is poor because the message states "Magnetic interference - move or calibrate". Two elements of that message are wrong and confusing if it is the time/distance recalibration: firstly there typically is no magnetic interference and, secondly, moving makes no difference. It should give a clear message that it is a firmware periodic recalibration request.
 
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Updated

here we are.
First I gave it a try with Assistant 2, the calibration hasn't been easy as supposed even though.I did it well only the first steps, then multiple error stated.
Then, with the aircraft and controller both of them updated to the same firmware I restarted again.
First controller, then mobile device, later the MP2.
With my S8, no way; the aircraft send "ready to Go" at the controller, event though the Go4 response, remains the same: Disconnected.
Meanwhile, the unfamous message, " Check App..Mag.." it's disappeared.
Then, I connected the iPad air 2 ( the old one with 9,7 dispaly, I mean..). Started the controller, started the app, and the connection established firmly.
No error message.Everithing was working as supposed.Didn't fly anywhere, just played with camera, and menu, calibrated the compass ( which one gave error to calibrate..) and all was good.
Then, reused the samsung S8, opened controller, opened the app, no connection established at all.Started the aircraft ready to go still, and no error message.
I dont' know what could I do to search a solution, but it's frustrating at least; in general I got used the S8 just for the smarter portability, I used the ipad only few for the bigger display look , but it's not my tool.

I thought it could be the wire even, but the connection is working seen the battery is charging with the controller attached.
:mad:
 
Arthuar: Cables are not all the same. Some can only provide power, some can only provide data, and finally, some can provide both. Be sure you have one that is at least for data and if you're not using the lower USB-A port on the bottom, you might wanna try it as it has a much better track record for reliability and function than the Micro-USB port on the top left of the RC. Additionally, there are good and bad quality cables so be sure you're using one of the latter. I'm a big fan of Anker gear and they make some great cables.
 
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They may or may not know what they are doing - there is no good technical reason to recalibrate just because you change location. Calibrating every 30 days might be useful in case the magnetic field of the aircraft has changed. Either way the implementation is poor because the message states "Magnetic interference - move or calibrate". Two elements of that message are wrong and confusing if it is the time/distance recalibration: firstly there typically is no magnetic interference and, secondly, moving makes no difference. It should give a clear message that it is a firmware periodic recalibration request.

Agreed. The implementation is quite poor and needs to be improved.

- If there’s actual magnetic interference, the drone should not be allowed to fly. A pop up should alert the user of said interference.

- If a compass calibration is needed because x-days have passed or location change, an on-screen popup notification should be displayed.
 
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Arthuar: Cables are not all the same. Some can only provide power, some can only provide data, and finally, some can provide both. Be sure you have one that is at least for data and if you're not using the lower USB-A port on the bottom, you might wanna try it as it has a much better track record for reliability and function than the Micro-USB port on the top left of the RC. Additionally, there are good and bad quality cables so be sure you're using one of the latter. I'm a big fan of Anker gear and they make some great cables.
Sure, even though I was informed about that, and I use only the best I can provide, appreciated you kind.

Thanks.

p.s. Tomorrow I am going to take a flight.We See.
 
The drone can't know whether it's magnetic interference or lack of calibration, since its only tools that could tell you (the magnetometers) are unreliable in that situation. So it makes sense for it to tell you to move first and then calibrate. In fact, it should also tell you to verify magnetic heading after calibration... I wish they added a 3D preview of magnetic heading to the app (since the magnetometers measure in 3D), it would be really helpful in solving the "reinforced concrete/underground cables" issue.
 
........ I wish they added a 3D preview of magnetic heading to the app (since the magnetometers measure in 3D), it would be really helpful in solving the "reinforced concrete/underground cables" issue.
That's an interesting idea. You would have to know the expected geoInclination in order to know if that seen in the 3D mag display isn't correct. That's not so hard but you do have to know it before launch.

I've often wondered what exactly the magnetic interference display is measuring. The term "inteference" is misleading as it suggests a noisy signal. AFAIK there are only two possibilities; field strength and field inclination.

1. The difference between measured and expected field strength. This makes a lot of sense to me since a distorted geoMagnetic field has to have some locations where field strength is either more or less than the uniform field strength of a non-distorted field. At the same time the AC could be sitting in one of those locations where the field strength is normal. That's why we see compass related incidents where the magnetic interference display is still in the green.

2. The difference between measured and expected geoInclination. The AC already computes the geoDeclination and the algorithms that do this also provide the geoInclination. Similar to the field strength above there will be locations where the measured inclination is OK making this also a less than sufficient measure.

If both of these are being used then I would like to see the magnetic interference display split; a strength deviation display, and an inclination deviation display.

There have been many incidents caused by launching in a distorted geomagnetic field but there was no indication of magnetic interference. In each of these incidents the heading indicator on the map would have been different than the actual AC heading.
 
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That's an interesting idea. You would have to know the expected geoInclination in order to know if that seen in the 3D mag display isn't correct. That's not so hard but you do have to know it before launch.

I've often wondered what exactly the magnetic interference display is measuring. The term "inteference" is misleading as it suggests a noisy signal. AFAIK there are only two possibilities; field strength and field inclination.

1. The difference between measured and expected field strength. This makes a lot of sense to me since a distorted geoMagnetic field has to have some locations where field strength is either more or less than the uniform field strength of a non-distorted field. At the same time the AC could be sitting in one of those locations where the field strength is normal. That's why we see compass related incidents where the magnetic interference display is still in the green.

2. The difference between measured and expected geoInclination. The AC already computes the geoDeclination and the algorithms that do this also provide the geoInclination. Similar to the field strength above there will be locations where the measured inclination is OK making this also a less than sufficient measure.

If both of these are being used then I would like to see the magnetic interference display split; a strength deviation display, and an inclination deviation display.

There have been many incidents caused by launching in a distorted geomagnetic field but there was no indication of magnetic interference. In each of these incidents the heading indicator on the map would have been different than the actual AC heading.

I made an attempt to correlate the interference level to field strength over in the other thread:

#104
 
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My 2 cents....

Having a background in Electrical/Electronic Engineering/digital circuit design and working with INS on Navy ships and aircraft like the F15 Eagle and F18 Hornet systems at McDonnel Douglas, I am still dumbfounded that it even works. From the Navy’s SINS gyro rack that weighs hundreds of pounds to today's quartz rate sensors using microscopic tuning fork gyros that weigh fractions of an ounce just makes your head hurt. (there are now in development nano gyros making the latter look gigantic)

I am also a private pilot and as any student pilot soon learns about that floating compass hanging off the windscreen, magnetic north ain’t north! The Earth’s geomagnetic field changes continually, the poles shift and even altitude distorts the dipolar nature of the field. You learn to use marked charts, the compass placard showing how your specific aircraft affects you compass and even your altitude, to correct you compass heading. And, once you do all that, 100 miles from here you get to correct it again because it’s changed.

Looking at some of the comments made, there are many angles presented on why this error happens. Some a technically advanced but there is an easier explanation.
  • Bad cables; doubt it. if everything else is working, the very nature of how data is transmitted on that connector precludes that. There isn’t any wire dedicate for compass.
  • Buried cables; doubt that. They would be low power lines (220 vac); doesn’t generate enough field and most of these tiny circuits is shielded just for that. No High-Power lines underground.
The “mag interference” is PLANET EARTH. As a pilot must re compensate for magnetic progression, so does your bird. Most of these devices can store information over some period of time on the chip using capacitive charges (like mini batteries). If the last flight remembered north and it now senses too much progression, it’s mag interference (you moved it). I’m sure the programmers were just looking to save a few bytes on what they thought were useless characters in memory, so we get a generic error.

The F15E Eagle introduced Ring Laser gyro design to come up immediately so they could scramble an alert. But if the ground crew moved that bird to the other side of the tarmac, you will wait for it to re-calibrate, including external device stimulus to help it “find itself”.

Holding your Mavic flat and turning 360 then rolling it on its side and turning it another 360 is a massive recalculation helping that lost compass re-find its way to the North Pole … (Occam get's it).
 
My 2 cents....

Having a background in Electrical/Electronic Engineering/digital circuit design and working with INS on Navy ships and aircraft like the F15 Eagle and F18 Hornet systems at McDonnel Douglas, I am still dumbfounded that it even works. From the Navy’s SINS gyro rack that weighs hundreds of pounds to today's quartz rate sensors using microscopic tuning fork gyros that weigh fractions of an ounce just makes your head hurt. (there are now in development nano gyros making the latter look gigantic)

I am also a private pilot and as any student pilot soon learns about that floating compass hanging off the windscreen, magnetic north ain’t north! The Earth’s geomagnetic field changes continually, the poles shift and even altitude distorts the dipolar nature of the field. You learn to use marked charts, the compass placard showing how your specific aircraft affects you compass and even your altitude, to correct you compass heading. And, once you do all that, 100 miles from here you get to correct it again because it’s changed.

Looking at some of the comments made, there are many angles presented on why this error happens. Some a technically advanced but there is an easier explanation.
  • Bad cables; doubt it. if everything else is working, the very nature of how data is transmitted on that connector precludes that. There isn’t any wire dedicate for compass.
  • Buried cables; doubt that. They would be low power lines (220 vac); doesn’t generate enough field and most of these tiny circuits is shielded just for that. No High-Power lines underground.
The “mag interference” is PLANET EARTH. As a pilot must re compensate for magnetic progression, so does your bird. Most of these devices can store information over some period of time on the chip using capacitive charges (like mini batteries). If the last flight remembered north and it now senses too much progression, it’s mag interference (you moved it). I’m sure the programmers were just looking to save a few bytes on what they thought were useless characters in memory, so we get a generic error.

The F15E Eagle introduced Ring Laser gyro design to come up immediately so they could scramble an alert. But if the ground crew moved that bird to the other side of the tarmac, you will wait for it to re-calibrate, including external device stimulus to help it “find itself”.

Holding your Mavic flat and turning 360 then rolling it on its side and turning it another 360 is a massive recalculation helping that lost compass re-find its way to the North Pole … (Occam get's it).

That's an interesting perspective, but it's wrong. The one thing that is not responsible for the magnetic interference message is the earth's magnetic field. There are two possible causes of that message:

Firstly, the measured magnetic field strength may be outside normal range or have an inclination that is inconsistent with the expected earth magnetic field at that location. That may be due to external interference, generally due to nearby ferromagnetic material, or it may be due to components on the aircraft that have become magnetized inadvertently. These issues are easily identified by looking at the magnetic interference level in the sensors section of the GO 4 app.

Secondly, especially for the Mavic 2 aircraft, it may be misleadingly generated when the aircraft has moved more than 50 km since its last flight, or it is more than 30 days since its last calibration. Neither of those imply any kind of magnetic interference - it's just using the generic message to request recalibration. The sensors interference display will not show interference in this case. The message can be ignored and the aircraft will still fly just fine.

As for the variations in the earth's magnetic field - the only one that matters for navigation is the local declination. That is not measured by the aircraft (it cannot be measured) and instead is determined from a global magnetic field model in the aircraft firmware. As soon as the aircraft has a GNSS position lock it sets the appropriate declination from the model, and records it in the DAT event stream in the following form:

-79.686 : 2254 [L-NS][AHRS] wmm dec: 11.687672​
-79.686 : 2254 [L-NS][AHRS] wmm inc: 59.062424​

Note that it also records the expected inclination, which it then appears to compare with the measured inclination.
 
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