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Testing of magnetic interference with large metal vehcile
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HedgeTrimmer
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There has been much discussion about Magnetic Interference from cars, rebar, buried steel, etc to drone's internal compass system.
In Mavic manuals, DJI only mentions being away from Magnetic Interference during compass calibration of drone.

DJI does not mention checking for Magnetic Interference in terms of degress of deviation from actual compass heading by Mavics or Smartdevices being used.
DJI does not give advice on how to check for Magnetic Interference to drone prior to takeoff.

Following are results of field (aka not Science Laboratory) testing I did for Magnetic Interference and electronic compasses.
?* Variations in hand position and movement towards vehicle vary by this much - to do more would require a sliding platform on a track to hold various devices steadily aimed.

Handheld GPS with digital compass:
15 degrees deviation starting at 06" from front of vehicle
15 degrees deviation starting at 18" from port side of vehicle
15 degrees deviation starting at 20" from starboard side of vehicle
15 degrees deviation starting at 24" from rear of vehicle
05?* degrees deviation starting at 48" from starboard side of vehicle

iPhone
05?* degrees deviation starting at 48" from starboard side of vehcile

Dronve vs. CrystalSky compass & map
Any noticeable deviation between two started around 30" from starboard side of vehicle  (Compasses on CS do not show degrees, and are constantly jumping around)

Deviation how much / to much?
15 degrees of compass deviation is vary little in terms of what one would expect to cause a drone to go Kamikaze.
Sudden change from say 180 (South) to 90 degrees (East) a person could see causing a crash.  Maybe even 0 (North) to 45 degrees (North East).
Realizing it took getting within 0.61 meters to see 15 degree deviation.  And 1.2 meters to see possible 05?* degree deviation.

Bare in mind, calibrating compasses are different matter.  There are recommendations of being at least 30-feet away from large steel building.  With distance in feet declining as size and amount of steel nearby declines.
   

Test source of steel
The vehicle used for Magnetic Interefernce is primarily made of steel, with a weight of 6.3 tons.  Which does include windows, rubber of tracks, misc plastics of cab, gas tank, etc.
Safe to say a lot of steel (5-tons) of which to cause magnetic interference to sensitive electronic compasses.
Not sure it matters but Front of vehcile was pointed approximately North.
  
Three things are needed from DJI:
1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk.
2) DJI providing specification for number of degrees of compass varation from magnetic north their drones can handle before drone is at risk.
3) When a compass error happens, DJI should handled it better than disabling GPS and IMU data.  Drone should hover without spinning, and allow pilot to land or slowly turn and move foward to land in safe spot.

Till then, DJI should honor warranty claims they say were do to Magnetic Inteference of compass, unless it is clear drone pilot ignored GO / GO-4 Magentic Interference warnings long enough that pilot could have reacted to take corrective action.



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Aardvark
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"1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk."

The system already does this, it will bring up an error.

"2) DJI providing specification for number of degrees of compass varation from magnetic north their drones can handle before drone is at risk."


Same as before, the system will bring up a warning.

"3) When a compass error happens, DJI should handled it better than disabling GPS and IMU data.  Drone should hover without spinning, and allow pilot to land or slowly turn and move foward to land in safe spot."

Most compass errors I've read about involved a badly calibrated compass, once correctly calibrated the compass should not need calibrated unless advised by system. If the system is getting conflicting directional data how can it orientate itself to hover ?

Given that most will not be flying this close to any vehicle, are the above tests meaningful ?
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Aardvark Posted at 2018-5-11 15:10
"1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk."

The system already does this, it will bring up an error.

> If the system is getting conflicting directional data how can it orientate itself to hover ?
Just as an example. I know that VPS was working here, but, even without VPS,  you don't really need directional data (apart from the yaw rate) to simply hover in ATTI mode (not necessarily holding position):


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asaw Posted at 2018-5-11 15:34
> If the system is getting conflicting directional data how can it orientate itself to hover ?
Just as an example. I know that VPS was working here, but, even without VPS,  you don't really need directional data (apart from the yaw rate) to simply hover in ATTI mode (not necessarily holding position):


"to simply hover in ATTI mode (not necessarily holding position):"

To hover means to hold position, otherwise it is just drifting. The only thing that ATTI will do is hold altitude based on the barometer reading.

Edit:- as you say VPS is holding position in this 'test'.
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Aardvark Posted at 2018-5-11 15:10
"1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk."

The system already does this, it will bring up an error.

"1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk."
The system already does this, it will bring up an error.


Unfortunately we have seen a recent case where it failed to warn pilot.  Only message involving compass was found in Flight Log and message did not appear until after drone had already taken off.


"2) DJI providing specification for number of degrees of compass  varation from magnetic north their drones can handle before drone is at  risk."
Same as before, the system will bring up a warning.


A warning is not a specificication that Pilots can consider and watch for before hand.  (See above)   Along with complete vaguness by DJI on pre-flight and flight Magenetic Interference, with DJI only warning about magnetic interference during compass calibration.


"3) When a compass error happens, DJI should handled  it better than disabling GPS and IMU data.  Drone should hover without  spinning, and allow pilot to land or slowly turn and move foward to land  in safe spot."
Most compass errors I've read about involved a badly calibrated compass,  once correctly calibrated the compass should not need calibrated unless  advised by system. If the system is getting conflicting directional  data how can it orientate itself to hover ?


Compass is not need to maintain XYZ position (as in Latitude, Longitude, or Altitude).  Compass is only needed to determine which direction nose of drone is pointing.  Inertial motion sensors should be able to tell drone whether it is rotating around compass axis (Z or Yaw).  Drone may end up pointing South instead of West, but should not keep drone from hovering.


Given that most will not be flying this close to any vehicle, are the above tests meaningful ?

Definetly not suggesting somebody should fly this close to or from any vehicle.  Only that separation distances posted around Internet are all over the place, and with little to no basis; other than perhaps the old - Somebody said 1-Meter, so doubling should be even safer.  Read where a person said 2-Meters was safer, so 4-meters would definelty be safe.
What is needed is for DJI to provide a firm minimum distance recomendation based on actual testing.  Along with how pilots can know in advance, not after the fact logs and crashes.


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HedgeTrimmer Posted at 2018-5-11 16:07
"1) DJI telling drone pilots how to detect Magentic Interefernce that is strong enough to potentially put our drones at risk."
The system already does this, it will bring up an error.

"A warning is not a specificication that Pilots can consider and watch for before hand.  "

So do you suggest pilots ignore system warnings ?

"Compass is not need to maintain XYZ position (as in Latitude, Longitude, or Altitude).  Compass is only needed to determine which direction nose of drone is pointing.  Inertial motion sensors should be able to tell drone whether it is rotating around compass axis (Z or Yaw).  Drone may end up pointing South instead of West, but should not keep drone from hovering."

In theory I would agree with that, but as soon as there is any horizontal, movement (even caused by wind) then any directional, data calculated from change in GPS co-ordinates would conflict with compass data (if incorrect). Ultimately causing the toilet bowl effect as the aircraft automatically tries to correct itself. Any major compass errors in the P4 for example, generate a system message to switch to ATTI mode to preserve the aircraft. In the Mavic Pro the switch to ATTI would be automatic, as I've not seen it yet I've no idea how quickly this would happen.

"What is needed is for DJI to provide a firm minimum distance recomendation based on actual testing.  Along with how pilots can know in advance, not after the fact logs and crashes."

The manual already suggests flying in open areas and avoiding metallic structures, and areas where there might be electromagnetic interference.

In practice how many of your flights have suffered from compass errors, whatever the cause ?

For me it's zero.
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I can see it now.
2 metres from motor bike
3 metres from small car
5 metres from Jeep
15 metres from truck
25 metres from train etc etc etc
Don’t think this will work, but statement for preflight in manual will explain.

I have a P4Pro and every time I switch to Atti mode it moves yes even in a calm wind, and in wind of 15mph it will take all of 5 seconds to reach 25mph try it an you will understand hover is not an option in these drones, in Atti mode.

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hallmark007 Posted at 2018-5-11 16:39
I can see it now.
2 metres from motor bike
3 metres from small car

Notice that #2 makes no mention of things like motor bikes, cars, SUVs trucks, or trains.  Let alone rebar in concrete or metal pipes in ground.  Instead #2 talks about tall or large metal structures "may affect" compass and GPS.

Which goes to my point.  DJI has not provided specifications as to how much compass deviation their drones can contend with.  Nor had DJI mentioned need for pilots to check for Magnetic Interference prior to flight or how to check for.
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Aardvark Posted at 2018-5-11 16:29
"A warning is not a specificication that Pilots can consider and watch for before hand.  "

So do you suggest pilots ignore system warnings ?

"A warning is not a specificication that Pilots can consider and watch for before hand.  "
So do you suggest pilots ignore system warnings ?


Did I say that?  No.  
Warning means something is about to go wrong or already has.  Unless you have precognitive abilities you can not take into consideration a warning that has yet to occur.   
Where as a specification that should be or must be met can be taken into consideration before hand.  Granted DJI would have to provide the how to.


"Compass is not need to maintain XYZ position (as in  Latitude, Longitude, or Altitude).  Compass is only needed to determine  which direction nose of drone is pointing.  Inertial motion sensors  should be able to tell drone whether it is rotating around compass axis  (Z or Yaw).  Drone may end up pointing South instead of West, but should  not keep drone from hovering."
In theory I would agree with that, but as soon as there is any  horizontal, movement (even caused by wind) then any directional, data  calculated from change in GPS co-ordinates would conflict with compass  data (if incorrect). Ultimately causing the toilet bowl effect as the  aircraft automatically tries to correct itself. Any major compass errors  in the P4 for example, generate a system message to switch to ATTI mode  to preserve the aircraft. In the Mavic Pro the switch to ATTI would be  automatic, as I've not seen it yet I've no idea how quickly this would  happen.


Movement around XYZ axis (roll, pitch, yaw) should be detected, along with any acceleration changes along XYZ axis (surge, sway, heave) by IMU.  All of which should be taken into consideration when there is a Compass Error.  Horizontal movement due to say wind should not result in toilet bowl effect.  Let alone rapid acceleration.

Anyway, from reading about DJI's system, a Compass Error results in GPS and IMU data being ignored.  Which pretty much dooms a drone when pilot is not made aware.  Even worse when drone itself seems to not be aware of what mode it is flying in.


"What is needed is for DJI to provide a firm minimum  distance recomendation based on actual testing.  Along with how pilots  can know in advance, not after the fact logs and crashes."
The manual already suggests flying in open areas and avoiding metallic  structures, and areas where there might be electromagnetic interference
.

A mixing of terms and warnings.  
Eletromagnetic interfernce is alluding to interference caused by radio transmissions sources such as Cell towers, high voltage lines, Ham radios, etc.
As for open areas, there in lies a hidden issue.  You can be standing in open area, and still have Magnetic Interference - at least according to various statements about Rebar in cement pavement, metal pipes, man-hole covers (I believe that was mine when someone was asking about possible causes), etc.  Would be interesting to take a poll of what drone pilots here believe an ''Open Area'' is or means.

DJI makes no statement about avoiding things like cars or motorcycles or  how far away (feet or meters) those objects should be prior to takeoff.  

On matter of unknown / hidden Magentic Inteference.  Unless I already knew there was 5-tons of steel parked in open area, and was specifically looking for Magnetic Interference, I would never have known it based on tests I did.  The compass deviations were so subtle that you would write those deviations off as inconsquential.  Or a matter of how you held Smartdevice with electronic compass, coupled with walking (body movement / no path to follow).  
I did not see any warnings from MPP, CS / GO-4 app of magnetic interference during testing.  I did see magnetic interference warning when I took MPP and CS inside a large metal building.  So I know it wasn't a case of my MPP / CS having a compass warning turned off, during testing.


In practice how many of your flights have suffered from compass errors, whatever the cause ?
For me it's zero.

None for me yet.   
Still based on recent Compass Error / Magnetic Infererence topics - I decided some more extreme testing (aka lots of steel) needed to be done.  It is a matter that calls for a reality check, and really calls for DJI to weigh in.

There is an additional concern here about droners wrongly getting a bad reputation from Toliet Bowl effect / unknown Magnetic Inteference / No Warnings.  Press, public, and politicians would have a field day if a drone doing a Toilet Bowl effect, ever accelerating to near max speed, flew into a person badly injuring them.


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HedgeTrimmer Posted at 2018-5-11 18:09
Notice that #2 makes no mention of things like motor bikes, cars, SUVs trucks, or trains.  Let alone rebar in concrete or metal pipes in ground.  Instead #2 talks about tall or large metal structures "may affect" compass and GPS.

Which goes to my point.  DJI has not provided specifications as to how much compass deviation their drones can contend with.  Nor had DJI mentioned need for pilots to check for Magnetic Interference prior to flight or how to check for.


I think you will find a car is a metal structure, you must realize that dji cannot know how much metal is buried in the ground and users cannot travel with shovel and pick to check, there is a certain  amount of savvy that can be used by users and thank god we can see this as a minute , the amount of compass problems we have seen that have no pilot error is very small, recent cases here clearly show that flying close to metal structures (cars) were clearly against best advice by dji in your manual.

One thing that is always very important to take from your manual and that is to fly and take off in open areas, taking off beside your car is not an open area. Also open areas have nothing to do with not having magnetic interference or metal buried beneath the ground, you are asked to do this simply because if anything goes wrong you have a much better chance of taking care of it, your Aircraft has built in failsafe to not fly higher than 16 ft and simply landing in open spaces is a lot easier than around tall structures.

If you don’t adhere to above then you have to show some responsibility, it is a very simple exercise to check compass while on the ground and should be on everybody’s preflight plan as well as open area .

I think we have seen in the last two weeks 3 problems with compass and 2 cases taking off close to and in one case I think that take off was actually from the hood of a car, in the other case it was clear that the urban envoirment was indeed a factor in the crash.

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I for one thank HedgeTrimmer for the time and trouble he took to produce the data he has.

I have seen pontifications form people here about the magnetic effects on compasses and although I have not experienced such issues, I put it down to avoiding reinforced concrete, power lines and mass metal.
I use a P3P as well as Mavic and just follow the rules.

it is still interesting to know the effects, even if not dramatic. At least we have data now and can avoid speculation.
PS. power and phone  lines with a current in them will produce a magnetic flux.
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AlansDronePics Posted at 2018-5-12 03:01
I for one thank HedgeTrimmer for the time and trouble he took to produce the data he has.

I have seen pontifications form people here about the magnetic effects on compasses and although I have not experienced such issues, I put it down to avoiding reinforced concrete, power lines and mass metal.

I put it down to avoiding reinforced concrete, power lines and mass metal.

As you should.  As I try too.  And everybody should try too.

I still plan to do some more testing.  
I know where there is 12" (rough guess) steel pipe buried several feet deep to not being buried at all.
Be interesting, given its long legth, to see at what distances it effects compasses.
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HedgeTrimmer Posted at 2018-5-12 07:07
I put it down to avoiding reinforced concrete, power lines and mass metal.

As you should.  As I try too.  And everybody should try too.

We will have to see which way it swings, won't we.
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AlansDronePics Posted at 2018-5-12 03:01
I for one thank HedgeTrimmer for the time and trouble he took to produce the data he has.

I have seen pontifications form people here about the magnetic effects on compasses and although I have not experienced such issues, I put it down to avoiding reinforced concrete, power lines and mass metal.

While you may call it pontificating, those people are in the main giving good advice, I’m sure OP is not offering his test as a means to judge how far you should be from metal structures as he said himself that test is not scientific, it is always better to take off a minimum of 10 metres from metal structures and if this advice is adhered to then the chances of magnetic interference occurring will be greatly reduced. And it would be true to say that any magnetic interference is a potential problem for these drones whether small or large .
It is prudent to check compass before taking off there are two pretty good methods and if this is checked by pilot then chances are he won’t get into difficulties.

I don’t believe people are pontificating but trying to give best advice to help those looking for it. If you choose to use the above results as a gauge then that’s up to you but I wouldn’t recommend anyone to put their aircraft on the ground in such close proximity to a car or large metal structure.
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hallmark007 Posted at 2018-5-12 02:34
I think you will find a car is a metal structure, you must realize that dji cannot know how much metal is buried in the ground and users cannot travel with shovel and pick to check, there is a certain  amount of savvy that can be used by users and thank god we can see this as a minute , the amount of compass problems we have seen that have no pilot error is very small, recent cases here clearly show that flying close to metal structures (cars) were clearly against best advice by dji in your manual.

One thing that is always very important to take from your manual and that is to fly and take off in open areas, taking off beside your car is not an open area. Also open areas have nothing to do with not having magnetic interference or metal buried beneath the ground, you are asked to do this simply because if anything goes wrong you have a much better chance of taking care of it, your Aircraft has built in failsafe to not fly higher than 16 ft and simply landing in open spaces is a lot easier than around tall structures.

it is a very simple exercise to check compass while on the ground and should be on everybody’s preflight plan as well as open area  

I agree with idea of checking compass.  At same time, it begs question - how to and what amount is too much?

As for how, you could set drone down in planned take off spot, back away and compare to GO-4 app compasses.  But compass is merely a pointer and pretty jumpy.
Knowing which way is North and pointing drone that way would be another.  GO-4 shows something other than North, timne to move drone.
Or using a Smartdevice that has a detailed compass would be another way.  Walking through area should not cause your compass to deviate from your heading.

Now we are back to how much compass deviation in degress is an indication of potential for compass problems / Toilet Bowl Effect?

Even if all we heard about is one crash per week that was tied back to Magnetic Intereference / Compass Error that is a lot.  Keeping in mind, not all Compass Error crashes get reported or reported here.

DJI's Engineers need weigh in on Magentic Interference and DJI's drones.  
What DJI's drones can detect and warn about, how much deviation can be tolerated, where there are gaps in compass system, and what we should do to avoid those gaps.



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hallmark007 Posted at 2018-5-12 07:42
While you may call it pontificating, those people are in the main giving good advice, I’m sure OP is not offering his test as a means to judge how far you should be from metal structures as he said himself that test is not scientific, it is always better to take off a minimum of 10 metres from metal structures and if this advice is adhered to then the chances of magnetic interference occurring will be greatly reduced. And it would be true to say that any magnetic interference is a potential problem for these drones whether small or large .
It is prudent to check compass before taking off there are two pretty good methods and if this is checked by pilot then chances are he won’t get into difficulties.

but I wouldn’t recommend anyone to put their aircraft on the ground in such close proximity to a car or large metal structure.  

Neither am I making such a recommendation.  

I am trying to point out there is Internet Lore, Good meaning Advice, Experienced based Advice, my non-laboratory testing, and the results differ greatly.
Which leads back to what I have said numerous times.  DJI Engineers need to provide drone pilots with facts, values, knowledge on Magnetic Interfence.


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I think it is safe to say that ANY magnetic interference is bad with these aircraft and if this rule is applied then problems will be greatly reduced.
It would be both foolish and wrong for any DJI engineers to say 5 degrees or 15 or any other figure. It would indeed serve no safety purpose whatsoever. And best advice always should be if you have a compass problem Don’t take off from that location.
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To check your compass just go to app settings, you can clearly see from above video that interference will show up on the metre , you can also check your compass needle lower left hand corner, it should be on the same heading as aircraft, and although you say it jumps about this is unique to CS , so maybe a FW update is needed there, it was a lot worse but has improved and when flying is pretty accurate, other devices don’t seem to jump about as much.
But I would recommend checking compass in app, and one thing I know about this if doing commercial exam you would be expected always to go through this procedure.
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hallmark007 Posted at 2018-5-12 08:03
I think it is safe to say that ANY magnetic interference is bad with these aircraft and if this rule is applied then problems will be greatly reduced.
It would be both foolish and wrong for any DJI engineers to say 5 degrees or 15 or any other figure. It would indeed serve no safety purpose whatsoever. And best advice always should be if you have a compass problem Don’t take off from that location.

For an engineer it is always good to be aware of precision and tolerances. Besides, you can't tell if an instrument functions correctly if you don't know its accuracy.
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There has been repeated mention of positioning takeoff point for drone YX-feet or XY-meters away from large structures, metal buildings, etc.  Found side outcome of a test meant for a different purpose - to be of interest in regards to large metal structures, compass and satellite interference.

Friday, I was trying to find a way to limit number of Satellites to see what Bars next to Satellite symbol would do.  Then try to limit signal strength of Satellites to once again see what Bars next to Satellite symbol showed, accompanied by what Satellite menu of Handheld GPS showed.

In case of limiting number of Satellites, I positioned Mavic Pro P and Handheld GPS receiver using 40x60 Metal building as shield.  One of two 9.5-foot wide by 10-foot high doors was open.  At one point, GO-4 app was reporting Good to Go (Green) with 9-Sats, 2-Bars, and no Magnetic Interference warnings or Compass Errors.  At another position GO-4 showed 7-Sats, 2 bars and Good to Go (Green).

As one would expect, going inside steel building, a Compass  Error message did show up, GO-4 showed Red and switched to ATTI mode.  Closer to opening Go-4 showed Yellow with message of No  Positioning (Atti), but there was no Compass Error showing.  Unfortunately I didn't take photos that show any reference point on floor of building for these two positions.  

But I did have pictures for 9-Sat / 2-Bars position mentioned above.  Using those pictures, I was able to figure out distance of that position.  
For 9-Sats with 2-Bars, the Mavic Pro and Handheld GPS were positioned inside building by 28".

Does this mean one should fly from inside a large metal building or next to one?  No!    Only that whole issue of Magnetic Interference is anything but clear.  

Forgot to mention, the floor of building is 6" thick concrete with metal cattle panels in it.  So is concrete pad in front of building where door openings are.
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asaw Posted at 2018-5-12 09:58
For an engineer it is always good to be aware of precision and tolerances. Besides, you can't tell if an instrument functions correctly if you don't know its accuracy.

Yes for engineers, but can you imagine if they said no problem taking off at 15 degrees deviation, you would be then faced with all those who said it was only 14/13/12.
If you have magnetic interference with compass the best advice is not to take a chance, the information given in your manual is for safe flying and best practices, it would not be a good idea to make this more complicated.
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HedgeTrimmer Posted at 2018-5-12 10:05
There has been repeated mention of positioning takeoff point for drone YX-feet or XY-meters away from large structures, metal buildings, etc.  Found side outcome of a test meant for a different purpose - to be of interest in regards to large metal structures, compass and satellite interference.

Friday, I was trying to find a way to limit number of Satellites to see what Bars next to Satellite symbol would do.  Then try to limit signal strength of Satellites to once again see what Bars next to Satellite symbol showed, accompanied by what Satellite menu of Handheld GPS showed.

You are given clear warnings as to where to fly and where not to fly in your manual. If you choose to take this to your own level of non scientific testing which is sounding more bizarre as you are determined to show, then you are not only risking having problems but risking the terms of your warranty. This is of no help to anyone particularly to new users who if decide to use manual as a guide to safe flying to protect their warranty is much safer for them and others and will be a much better guide to flying these aircraft.

I think what you should do is show everything you are doing on video and let’s have the discussion.
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hallmark007 Posted at 2018-5-12 10:24
Yes for engineers, but can you imagine if they said no problem taking off at 15 degrees deviation, you would be then faced with all those who said it was only 14/13/12.
If you have magnetic interference with compass the best advice is not to take a chance, the information given in your manual is for safe flying and best practices, it would not be a good idea to make this more complicated.

As you well know, Magnetic Interference is not always being detected, and in those cases the Drone Pilots are not getting any warnings.  

As such when there is warnings, one needs to take steps to eliminate warnings.
Issue is assumption coming out of that.  No Magnetic Interference warnings or Compass Error means a drone pilot is safe to fly, which several cases are showing to be wrong.
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hallmark007 Posted at 2018-5-12 10:35
You are given clear warnings as to where to fly and where not to fly in your manual. If you choose to take this to your own level of non scientific testing which is sounding more bizarre as you are determined to show, then you are not only risking having problems but risking the terms of your warranty. This is of no help to anyone particularly to new users who if decide to use manual as a guide to safe flying to protect their warranty is much safer for them and others and will be a much better guide to flying these aircraft.

I think what you should do is show everything you are doing on video and let’s have the discussion.

You are given clear warnings as to where to fly and where not to fly in your manual.  

You have said that several times, and everytime it has been pointed out those warnings do not cover cases of hidden or unknown magnetic interference.  Nor is it least bit clear that a car or motorcycle in open area means open area is not.  DJI simply does not provide information as to what constitutes an Open Area.  There is also an issue of mixing of Magnetic Interference with Electronmagnetic Inferference - two different things.


sounding more bizarre as you are determined to show,

Why are you so dead set against getting DJI to present numbers, facts, guidiance?
Do you like idea of misinformation (aka Internet Fables / the old if 1 is good, 2 is better, 4 is better yet) being passed off as fact?



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hallmark007 Posted at 2018-5-12 10:24
Yes for engineers, but can you imagine if they said no problem taking off at 15 degrees deviation, you would be then faced with all those who said it was only 14/13/12.
If you have magnetic interference with compass the best advice is not to take a chance, the information given in your manual is for safe flying and best practices, it would not be a good idea to make this more complicated.

Yes for engineers, but can you imagine if they said no problem taking  off at 15 degrees deviation, you would be then faced with all those who  said it was only 14/13/12.   

I can imagine that.  DJI would have to start ensuring their Drones / RC / GO app gave pilot warnings prior to takeoff.  Along with writting their manuals to be clear and concise.  And DJI could not declare after a crash there was no warranty covreage because DJI says there was magnetic interference based on something that only appeared in BlackBox or Flight Log file, thus giving pilot no warning or chance to avoid.

There is to much Hyperbole floating around about safe distances involving Magentic Interference.  DJI needs to weigh in on topic of Magnetic Interference with facts, values, and ways to detect.   

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HedgeTrimmer Posted at 2018-5-12 12:06
Yes for engineers, but can you imagine if they said no problem taking  off at 15 degrees deviation, you would be then faced with all those who  said it was only 14/13/12.   

I can imagine that.  DJI would have to start ensuring their Drones / RC / GO app gave pilot warnings prior to takeoff.  Along with writting their manuals to be clear and concise.  And DJI could not declare after a crash there was no warranty covreage because DJI says there was magnetic interference based on something that only appeared in BlackBox or Flight Log file, thus giving pilot no warning or chance to avoid.


It’s hard to know how to answer some of this, but I will try.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

2/( what constitutes an open area) the fact that you have to ask, says a lot more about you than it does about users of these drones.
If you are in an open area without obstacles and metal structures and you bring a car/motorbike into this area you are no longer in an open area without obstacles or metal structures.

3/ there is nowhere in your manual that tells you that at all times you will get warnings regarding compass.

4/ if you are reading urban myths or taking your information from the internet then you are going to be in exactly the same place you are in now, much confusion, just as well dji doesn’t ask users to get their information from the same place as you.

( why am I so dead set against dji presenting facts)
I take a very pragmatic view on this, I fly drones from spark to matrice 600, and in all the drones I fly none of them offer the level of information you are looking for, and while I say this I would like you to point me to the drones in the price bracket of  ie MavAir and Mavic Pro that offer such detailed information.
I have been with these drones for a number of years now and have seen both safety features and telemetry improve no end with the continued improvements in technology, and I believe it will continue to improve safety as we see improvements in technology.
Dji have never been shy about safety features in their drones and anyone who thinks it’s not in their interest to make these drones as safe as possible for the price they are paying for them is not thinking straight.

We know now that 99% of users have no real problems with compass when they follow good practice, we also know that 99% of users who have problems with compass don’t follow good practice, so end up with problems.

This is not rocket science if you follow the manual you won’t go far wrong, these drones just like all tech your phone, computer, and all things tech, crash and have problems, if you think you can cure all the ails of your drone without paying for it you are delusional.

The very best advice around here by both dji and members is RTFM, you choose to deviate continually from this, that’s your choice but telling others is not going to help anyone.
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hallmark007 Posted at 2018-5-12 13:35
It’s hard to know how to answer some of this, but I will try.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

Two things:
1) There you go again with name calling.  
2) It did accomplish purpose, it got you to acknowlege that I asked you:
Why are you so dead set against getting DJI to present numbers, facts, guidiance?
Do you like idea of misinformation (aka Internet Fables / the old if 1  is good, 2 is better, 4 is better yet) being passed off as fact?

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hallmark007 Posted at 2018-5-12 13:35
It’s hard to know how to answer some of this, but I will try.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

2/( what constitutes an open area) the fact that you have to ask, says a lot more about you than it does about users of these drones.  

An ''open area'' is absolutely vague when you are dealing with people of different countries, cultures, or living area.
For example:
''open area'' to someone who lives in crowded city like Tokyo, with hotels that have tube chambers for beds - an open area could be 7-meter x 7-meter garden.
''open area'' to someone who lives in vast spaces of Wyoming, with no hotel for miles - an open area could be a section 1609-meters x 1609-meters.
''open area'' to others can be a city park with trees
''open area'' to some of peers who worked in hi-tech manufacturing - an open area was empty square spot between four buildings with pinic table and chairs.

Point being, ''open area'' means different things to people other than you.

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hallmark007 Posted at 2018-5-12 13:35
It’s hard to know how to answer some of this, but I will try.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

4/ if you are reading urban myths or taking your information from the internet then you are going to be in exactly the same place you are in now, much confusion, just as well dji doesn’t ask users to get their information from the same place as you.

How ironic coming from very person who can't back up his pontifications.  
If you are done SPINNING and Blowing Spoke; you take note that I am one who as repeatedly called for DJI to weigh in.   Whereas it is you who dismiss such a call with more blah, blah, blah, blah, blah.

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hallmark007 Posted at 2018-5-12 07:42
While you may call it pontificating, those people are in the main giving good advice, I’m sure OP is not offering his test as a means to judge how far you should be from metal structures as he said himself that test is not scientific, it is always better to take off a minimum of 10 metres from metal structures and if this advice is adhered to then the chances of magnetic interference occurring will be greatly reduced. And it would be true to say that any magnetic interference is a potential problem for these drones whether small or large .
It is prudent to check compass before taking off there are two pretty good methods and if this is checked by pilot then chances are he won’t get into difficulties.

I’m sure OP is not offering his test as a means to judge how far you should be from metal structures as he said himself that test is not scientific, it is always better to take off a minimum of 10 metres from metal structures and if this advice is adhered to then the chances of magnetic interference occurring will be greatly reduced.

Is that your opinion or fact that you can point too?

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HedgeTrimmer Posted at 2018-5-13 11:24
2/( what constitutes an open area) the fact that you have to ask, says a lot more about you than it does about users of these drones.  

An ''open area'' is absolutely vague when you are dealing with people of different countries, cultures, or living area.

You know you are just sounding silly here, we are talking about open areas without obstacles, if you can’t figure what an open area constitutes for flying drones then you have a real problem.

Next you will be demanding to know width/length/height/circumference of an open area from dji.
As I said in earlier post most people here have a bit of savvy, I have never heard such a silly question here on this forum.

Dji should set parameters for open areas in Tokyo Paris Milan the gobi desert the Grand Canyon, its time to knock this one on the head.
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HedgeTrimmer Posted at 2018-5-13 11:12
1/ blowing up the size of your font text to make your point just makes you look like an idiot.

Two things:

It accomplished nothing, you presume something about me put it up in your best large font, then I have to explain it’s not true. It’s childish.
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hallmark007 Posted at 2018-5-12 13:35
It’s hard to know how to answer some of this, but I will try.

1/ blowing up the size of your font text to make your point just makes you look like an idiot.

We know now that 99% of users have no real problems with compass when  they follow good practice, we also know that 99% of users who have  problems with compass don’t follow good practice, so end up with  problems.  

99% / 99% coming from what study on drone compasses, magnetic interference, and drone pilots?
Did study take into consideration:
Compass calibration issues
Faulty compasses
Poorly written software / firmware bugs
Drone Pilot errors vs. poorly written manuals or vauge writting
and lastly actual Magnetic Interference

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hallmark007 Posted at 2018-5-13 11:36
It accomplished nothing, you presume something about me put it up in your best large font, then I have to explain it’s not true. It’s childish.

Au Contraire!

You can't deny having read two questions.  Because you griped about font questions were written in.
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hallmark007 Posted at 2018-5-13 11:34
You know you are just sounding silly here, we are talking about open areas without obstacles, if you can’t figure what an open area constitutes for flying drones then you have a real problem.

Next you will be demanding to know width/length/height/circumference of an open area from dji.

So you are saying everybody, no matter where they live, how they grew up, knows that an open space is XY by YX meters with absolutely nothing in that area other than say bare ground?  
That everyone asked to define an open area or open space, would answer the same as ''hallmark007''?

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hallmark007 Posted at 2018-5-13 11:34
You know you are just sounding silly here, we are talking about open areas without obstacles, if you can’t figure what an open area constitutes for flying drones then you have a real problem.

Next you will be demanding to know width/length/height/circumference of an open area from dji.

Dji should set parameters for open areas in Tokyo Paris Milan the gobi desert the Grand Canyon, its time to knock this one on the head.  

Oh how you wish.  But there is more information I got coming.  Information that you will naturally try SPIN, TWIST, and Dismiss.

Along with a TIP, start of TIP, I believe can be developed into a way for Drone Pilots to minimize chances of unknown / hidden Magnetic Interference, thus minimizing chances of Crashes.


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HedgeTrimmer Posted at 2018-5-13 11:55
Dji should set parameters for open areas in Tokyo Paris Milan the gobi desert the Grand Canyon, its time to knock this one on the head.  

Oh how you wish.  But there is more information I got coming.  Information that you will naturally try SPIN, TWIST, and Dismiss.

Anyone who doesn’t know what an open area for flying drones is, should make sure if he is giving out tips that they are right and correct.
I hope this information is video based, tried and tested...

Judging by lack of replies on this thread, not to many veering away from best practice. And incidentally compass calibration is not an issue, it’s part and parcel of owning drones.
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One thing that needs a reality check is TBE or Toilet Bowl Effect.  
Toilet Bowl Effect is not simply a drone making a long sweeping 90 or 180-defgree arc, while accelerating along that arc.  TBE is swirling motion by drone is series ever expanding circles, starting out small in size to increasing larger circles.

As shown in this TBE video.


You will find other videos showing TBE, but most only show last large circle before crash, skipping initial small circles.  Along with Drone pilot interacting with drone, which masks TBE, with corrections or switching modes, during video.

From reading up on cause of TBE, primary cause is lack of or bad Compass Calibration.  In some cases Compass being mounted incorrectlly at factory (depends on drone maker / type).  Along with Compass that for whatever reason are problematic to calibrate.  Another is failure to compensate correctly for Earth's magnetic declinations.

Later of which brings up an interesting point.  Based on drone pilot reports of compass problems, somewhere near 15 degrees (or higher) of uncorrected magnetic declination is where Compass Calibration problems start to cause flight problems.  Usually first noticed when drone is commanded to fly straight forward, but as drone flys, the nose is aimed slightly off to left or right.

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HedgeTrimmer Posted at 2018-5-13 11:48
So you are saying everybody, no matter where they live, how they grew up, knows that an open space is XY by YX meters with absolutely nothing in that area other than say bare ground?  
That everyone asked to define an open area or open space, would answer the same as ''hallmark007''?

I was born and raised in a city of 1.5 million people, I know what an open area with no obstacles for flying drones is.
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hallmark007 Posted at 2018-5-13 12:18
Anyone who doesn’t know what an open area for flying drones is, should make sure if he is giving out tips that they are right and correct.
I hope this information is video based, tried and tested...

Lame remark at best.
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