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Avoid Crash due to Compass Interference
29743 380 2017-7-11
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A J
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AntDX316 Posted at 5-30 23:45
If I'm asking, I'm seeking some sort of verification like how our GPS systems work in the drones.

It's all in the manual. You'll do well reading it
5-30 23:47
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AntDX316
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A J Posted at 5-30 23:47
It's all in the manual. You'll do well reading it

You're right.  Atti mode is pretty much the failsafe method probably installed after the mass Wookong DJI A2 S800 crash study.
5-30 23:56
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A J
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AntDX316 Posted at 5-30 23:56
You're right.  Atti mode is pretty much the failsafe method probably installed after the mass Wookong DJI A2 S800 crash study.
[view_image]

There you go - now keep reading and hopefully the need to post rhetorical questions will stop...
5-30 23:58
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AntDX316
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A J Posted at 5-30 23:58
There you go - now keep reading and hopefully the need to post rhetorical questions will stop...

I mean, I thought it would only not work when it's dark but being too bright and angled surfaces is interesting.. though I should look into how terrain follow mode works in detail.  I never really trust the systems like that as it doesn't always work as it should.
5-31 00:04
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hallmark007
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Labroides Posted at 5-30 20:08
there are a lot less compass problems with these aircraft, so hopefully for whatever reasons dji has managed to tweak problems with compass for the better
Actually the compass has always been trouble free.
The problems have always come from operators not understanding the compass or compass calibration.

While i agree with all you say, there is a notable decrease with compass problems in fact almost none in MavAir and M2, or at least extremely rare, whether it’s down to something as simple as better sealing or position of compass in these craft I’m not sure, but I would not think it’s down to better educated users, so while everything you say is correct, it doesn’t explain why we see so few problems with compass in new craft .
5-31 01:06
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hallmark007
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AntDX316 Posted at 5-30 21:15
"1/ Never calibrate Compass unless prompted to."

This is wrong.  The compass interference rises at times, no idea why.  I get interference in the hundreds.  It gets reset back to a low single or 2 digits green number After calibrating.  The weirdest thing is when you calibrate when it has interference that the numbers are really low.  Now, I'm wondering if you calibrate in an open field, is that better than calibrating in a hard interference area because if you can get low numbers in a hard interference area then the open field calibration should be even lower.  If you calibrate in an open low interference area the interference tolerances would be A lot word when being in a high interference area.  It would be easier if we had a compass engineer tell us what is truly going on so we can make an optimal decision on when and where to calibrate.  Right now, we are all pretty much guessing and those unfortunate ones who do it wrong, lose their drone and worse.

I’m afraid none of what you say makes any sense, so it leads me to believe your comments are not genuine, they are so far off the mark, they could have been written by someone in preschool.
I think most people like commenting back and forth when there is something to Be learnt from one or other.
What your saying is tantamount to pure drivel .
5-31 01:19
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AntDX316
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hallmark007 Posted at 5-31 01:19
I’m afraid none of what you say makes any sense, so it leads me to believe your comments are not genuine, they are so far off the mark, they could have been written by someone in preschool.
I think most people like commenting back and forth when there is something to Be learnt one or other.
What your saying is tantamount to pure drivel .

Don't calibrate your compass then.  I don't even calibrate mine with the Mavic 2 Zoom even when it says calibrate it but I do w/ my P4P V2.0 as I'm worried the system design of 2016, I can get away with cheating the system as the Compass 2 on the Mavic 2 is VPS.  I think it could be ok though.  All the sense I have is from real-world information and engineering.  The people are talking from a level above that (surface wise not the deep core essence) which is flawed.  It involves rapport and sometimes extreme rapport to learn and trust who to believe.

I look at the numbers after calibration and they drop significantly.
5-31 01:28
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Labroides
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hallmark007 Posted at 5-31 01:06
While i agree with all you say, there is a notable decrease with compass problems in fact almost none in MavAir and M2, or at least extremely rare, whether it’s down to something as simple as better sealing or position of compass in these craft I’m not sure, but I would not think it’s down to better educated users, so while everything you say is correct, it doesn’t explain why we see so few problems with compass in new craft .

Compass problems?
We don't see any compass problems, we see operator problems.
A compass error is not something wrong with the compass that needs to be fixed.
It's a properly working compass that's warning that it's detected a magnetic problem in the local environment.
Calibrating the compass doesn't "fix" anything and will never fix the issue the compass is warning about.
Better sealing?  The compass has to be sensitive to small magnetic fields or it's not useful as a compass.
I suspect there is no change in what you are perceiving as compass problems.
I still see plenty of users having troubles and blaming their compass.
There's certainly no significant improvement in user education and no shortage of people totally ignorant of how the compass works.



5-31 17:51
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Labroides
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AntDX316 Posted at 5-30 21:15
"1/ Never calibrate Compass unless prompted to."

This is wrong.  The compass interference rises at times, no idea why.  I get interference in the hundreds.  It gets reset back to a low single or 2 digits green number After calibrating.  The weirdest thing is when you calibrate when it has interference that the numbers are really low.  Now, I'm wondering if you calibrate in an open field, is that better than calibrating in a hard interference area because if you can get low numbers in a hard interference area then the open field calibration should be even lower.  If you calibrate in an open low interference area the interference tolerances would be A lot word when being in a high interference area.  It would be easier if we had a compass engineer tell us what is truly going on so we can make an optimal decision on when and where to calibrate.  Right now, we are all pretty much guessing and those unfortunate ones who do it wrong, lose their drone and worse.
This is wrong.
What's wrong is almost every stupid word you type.
You have very little knowledge of anything related to your drone or how it operates and even less understanding of how little you know.
No-one should pay any attention to the garbage you post.

You'd do well to stop posting for a month and just read.

It would be easier if we had a compass engineer tell us what is truly  going on so we can make an optimal decision on when and where to  calibrate.  Right now, we are all pretty much guessing and those  unfortunate ones who do it wrong, lose their drone and worse.
I'll tell you but you probably won't pay any attention and won't learn anything.
Calibrating your compass has nothing to do with where you are as long as there's no spurious magnetic fields very close by).
Once your compass is calibrated (and it probably was before you opened the box), there's no need to do it again.
Unless you :
1.  Modify your drone  .. or
2.  You bought one of those Mavic 2 drones that DJI forces you to unnecessarily recalibrate from time to time.

Understanding what compass calibration actually does is the key ... and you have no idea of that.

5-31 17:55
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AntDX316
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Labroides Posted at 5-31 17:55
This is wrong.
What's wrong is almost every stupid word you type.
You have very little knowledge of anything related to your drone or how it operates and even less understanding of how little you know.

I understand your issues but even the Note 9 and other Samsung phones ask to calibrate for some reason even after calibrating.  You can get away w/o calibrating at all, it being off and still being ok.  We all can.  People probably crash because of something not compass related.
5-31 19:32
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Labroides
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AntDX316 Posted at 5-31 19:32
I understand your issues but even the Note 9 and other Samsung phones ask to calibrate for some reason even after calibrating.  You can get away w/o calibrating at all, it being off and still being ok.  We all can.  People probably crash because of something not compass related.

Like I said, once your compass is calibrated, it's not necessary to ever calibrate it again.
It's done and that's all there is to it.
Your compass doesn't go out of calibration, it doesn't go off.
It's always OK.

But you'd have to understand what calibrating the compass really does and how it doesn't "fix" anything.
But you don't.
6-1 00:04
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AntDX316
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Labroides Posted at 6-1 00:04
Like I said, once your compass is calibrated, it's not necessary to ever calibrate it again.
It's done and that's all there is to it.
Your compass doesn't go out of calibration, it doesn't go off.

I will calibrate in a super open field and leave it but the only way to tell if you are not near anything interfering is to have some sort of magnetic interference sensor.  If you calibrate over an open field that is over a fault line like some people did, they would lose their drone but I'm not sure how the compass even matters.  There is no such thing as a compass on some DIY multi-rotors.

Would this work as I assume you portray yourself as the compass expert here?
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6-1 00:28
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Labroides Posted at 6-1 00:04
Like I said, once your compass is calibrated, it's not necessary to ever calibrate it again.
It's done and that's all there is to it.
Your compass doesn't go out of calibration, it doesn't go off.

I agree!
Calibration is unnecessary until DJIGO4 requests.
The real problem with Spark is that there is only one compass, so it is not possible to determine whether the disturbance is real or just the malfunction of the cheap compass ...
If you have 2 compasses (eg mavic, phantom, inspire) then the firmware is simple:
- 1 compass error, 2 compass fine = internal fault, no action
- 1 compass error, 2 compass error = interference, ATTI mode
6-1 00:46
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AntDX316 Posted at 3-25 15:13
If you don't calibrate the compass you can get drift and a tilted quadcopter when doing nothing.  I didn't calibrate out of the box for a while but was noticing how the horizon is Always tilted and it drifting.  After calibrating it fixed it.

It was "normal" all the time unless it's on something metal like a hood or on the ground

The inclination of the horizon is not caused by the compass. IMU is responsible for controlling the drone movement.
In this situation, the IMU should be calibrated and not the compass.
6-1 00:52
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hallmark007
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Labroides Posted at 5-31 17:51
Compass problems?
We don't see any compass problems, we see operator problems.
A compass error is not something wrong with the compass that needs to be fixed.

What your talking about is more to do with the semantics of the whole thing, most users are well aware if they put their drone on a ton of steel the compass will have problems, and if the take it off compass problems will be gone, so I’m certain most users can figure out what’s causing the problem, not the compass but the steel, maybe give users some credit.
I’m not to sure where you seen I said calibrating compass will fix anything , but if you own a MavAir or a Mavic 2 you won’t fly unless you calibrate.

While you still see users having problems with their drones as I do, I still say there is a marked improvement in those who own M2 and MavAir, you can go through the forum and you will see this for yourself , and I don’t think it’s just a coincidence, but more likely improvements in building newer craft, if you know something to the contrary then maybe show us .

6-1 01:27
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Labroides
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AntDX316 Posted at 6-1 00:28
I will calibrate in a super open field and leave it but the only way to tell if you are not near anything interfering is to have some sort of magnetic interference sensor.  If you calibrate over an open field that is over a fault line like some people did, they would lose their drone but I'm not sure how the compass even matters.  There is no such thing as a compass on some DIY multi-rotors.

Would this work as I assume you portray yourself as the compass expert here?

but the only way to tell if you are not near anything interfering is to  have some sort of magnetic interference sensor.
If only the drone had some sort of magnetic sensor built-in.
Something that could detect magnetic fields and the identify the direction of their force lines.

but I'm not sure how the compass even matters.  
Of course .. there's so much you aren't at all knowledgeable about.
But that doesn't stop you trying to lecture everyone with half-baked theories.

Would this work as I assume you portray yourself as the compass expert here?
Do you know what a compass is and what it does?


6-1 05:48
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Labroides
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hallmark007 Posted at 6-1 01:27
What your talking about is more to do with the semantics of the whole thing, most users are well aware if they put their drone on a ton of steel the compass will have problems, and if the take it off compass problems will be gone, so I’m certain most users can figure out what’s causing the problem, not the compass but the steel, maybe give users some credit.
I’m not to sure where you seen I said calibrating compass will fix anything , but if you own a MavAir or a Mavic 2 you won’t fly unless you calibrate.

What your talking about is more to do with the semantics of the whole thing, most users are well aware if they put their drone on a ton of steel the compass will have problems, and if the take it off compass problems will be gone
Except in the rare situation where the magnetic field associated with the steel is aligned exactly the same way as the earth's magnetic field, that's a very good way to come to grief with a yaw error.
The greater the difference between the directions of the magnetic fields, the bigger the problem and the more likely the drone is to crash seriously when the drone departs the mag field of the steel object and turns to face another direction.
I see this sort of mistake every week and the result is usually quite bad.
Never powerup or launch from close to steel objects or reinforced concrete, it's about the worst thing you can do with your drone.

you can go through the forum and you will see this for yourself, and I  don’t think it’s just a coincidence, but more likely improvements in  building newer craft, if you know something to the contrary then maybe  show us
I haven't carried out any kind of survey but from the forums I read, my perception is the opposite.
My guess has been that it's due to the large number of new users coming in since the M2 series was released.
I don't believe there's any fundamental improvement in the compass technology.
It's hard to imagine how there could be, but I'm not aware of any inherrent problems with compasses, old or new.

6-1 06:02
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hallmark007
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Labroides Posted at 6-1 06:02
What your talking about is more to do with the semantics of the whole thing, most users are well aware if they put their drone on a ton of steel the compass will have problems, and if the take it off compass problems will be gone
Except in the rare situation where the magnetic field associated with the steel is aligned exactly the same way as the earth's magnetic field, that's a very good way to come to grief with a yaw error.
The greater the difference between the directions of the magnetic fields, the bigger the problem and the more likely the drone is to crash seriously when the drone departs the mag field of the steel object and turns to face another direction.

I’m not sure how you manage your perception, but I’m telling you if you compare for instance Mavic Pro to M2 , you will find that fall in craft crashing because of “compass” related problems is vast , and one thing we do know is there was a change in compass system from Mavic Pro to M2, change consisting of two compass in Mavic Pro one in M2 and Only a blind man couldn’t see the clear difference in compass associated problems between these two craft, I would hazard a guess that Mavic Pro with compass problems would have been almost 1/2 a week showing up here, M2 I would say that since it’s release less than a handful showing up here. So yes I would say something changed .
6-1 08:45
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Labroides Posted at 6-1 05:48
but the only way to tell if you are not near anything interfering is to  have some sort of magnetic interference sensor.  
If only the drone had some sort of magnetic sensor built-in.
Something that could detect magnetic fields and the identify the direction of their force lines.

but the only way to tell if you are not near anything interfering is to  have some sort of magnetic interference sensor.
If only the drone had some sort of magnetic sensor built-in.
Something that could detect magnetic fields and the identify the direction of their force lines.


As has been mentioned before, you can download free (or nearly free) Android and iOS Apps that will show magnetic force lines of a SmartDevice's compass.  Compass is composed of three magnetic field sensors for X, Y, Z axis.  Apps will show deviations from Earth's normal magnetic field.  Which can be an increase (source of magnetic field) or decrease (source acting as shield) in magnitude.  Some of Apps have ability to show individual XYZ sensors strength vs. simple combine value for XYZ sensors.



Mavic Pro uses two electronic compasses (primary & backup) for total of six magnetic field sensors (Xp/Xb, Yp/Yb, Zp/Zb).  You can use drone's magnetic field sensors to detect sources of magnetic field interference.  Raising drone or moving drone should not result in significant change to GO-4 App's magnetic interference bar.  Bar(s) should be green and short in length.  Mavic Pro with two electronic compasses has advantage in that a source of magnetic interference is generally closer to one of it's two compasses, unless drone is directly over or under source of magnetic field interfernce.  By rotating drone, you can get idea of where source is.  Understanding moving drone as little as several inches can result in Good-to-Go or Warning of Magnetic field interference.


** Assuming SmartDevice's compass or drone's internal compass(es) have been properly calibrated.











6-1 21:36
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hallmark007
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Labroides Posted at 6-1 00:04
Like I said, once your compass is calibrated, it's not necessary to ever calibrate it again.
It's done and that's all there is to it.
Your compass doesn't go out of calibration, it doesn't go off.

I do fully agree with you once compass is calibrated correctly it never needs to be calibrated again including when moving large distances, as someone who owns P4Pro Mavic Pro , I have calibrated P4Pro once since I got it and Mavic Pro twice, and have had only one warning to calibrate Mavic Pro, I don’t have any need or urge to calibrate either again.

With MavAir and Mavic 2 compass calibration is forced on these two craft and yes unnecessarily, but there is no way around it .

We have also seen change in the Mavic pro manual where it now advises calibration every 50km which I have and will completely ignore .
6-3 03:35
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hallmark007 Posted at 2017-7-11 13:40
Tip To Help Avoid compass interference and crash.

I read this before my first flight and I have done it every time without exception.  Also, I follow the rule also suggested (I believe) by @Hallmark007, to lock no less than 11 sats before take-off.

And (knock wood) so far I haven't had any issues.

Thank you, sir.

6-3 09:26
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