Been having some strange issues with my month old Spark. Among them, the DJI Go app saying I'm pointing in a direction other than then one I am, and having to often calibrate iPhone compass. Or having my heading show correctly, but then locking/unlocking the screen or momentarily switching apps (such as settings), and coming back to the the DJI app to see that my apparent heading has changed by about 20-25 degrees. Yesterday and today I started having compass/yaw errors and thought maybe my AC compass needed calibration.

So I bought an analog compass to see if the Spark knows which way North is. And as far as I can see it does. I point the compass towards 'north', I point the Spark in the same direction, and from what I can see, it consistently knows were north is. Sidenote: I'm in Nashville where the difference between True North and Magnetic North is only a 3 degree deviation.

What is often wrong is the direction the DJI Go app says that I am pointing in, and on the app it will show that myself and my AC are not pointing in the same direction when in fact they are.


So I began to experiment and I discovered that I wouldn't have any issues until I placed the phone into the remote control. The remote could be complete off and my iPhone compass and the DJI Go compass would now say that north was somewhere it wasn't, usually off by about 20-30%. I could replicate this each of the times I tried it.

In this video you can see that before the test, everything is pointing north. I slowly move the compass over and near the RC and you can see the needle move all around. I showed the same thing with and iPhone 5. Same results with my iPhone 6 but I used it to film. This happens with with or without the AC being connected and with or without the RC even being powered on, let alone connected.

I'm also going to do the test outside in a wide open area to rule out any indoor interferance.

Some work-arounds that seem to help: 1) Calibrating the phone compass, while it's inside the RC.  and 2) Placing the phone as far away from the RC as possible while still being securely attached.

Correct me if I'm wrong but this can't be good. Could this be a cause of compass errors and flyaways?

like poles repel and unlike poles attract....same is the case when you bring two compass together....i guess !!

S.J Posted at 2017-12-10 21:39
like poles repel and unlike poles attract....same is the case when you bring two compass together....i guess !!

There's no internal compass in the RC though.

ernie_halter Posted at 2017-12-10 21:43
There's no internal compass in the RC though.

Hi, Ernie. Please note that RC has magnetic components inside it. I would recommend you test the compass of spark outdoor. Thanks for your hard work.

quote: Calibrating the phone compass, while it's inside the RC.

I calibrate the Phone compass like you have described here and all goes well after that. Only moving throttle up stick or down let the app compass moves east and comes back after letting the stick go.

The rc sticks use hall effect sensors instead of potentiometers, so there are magnets in the sticks.
A big question is which role the phone compass plays for the spark.

What do you think dji this can't be good ?

heliman Posted at 2017-12-11 06:02
The rc sticks use hall effect sensors instead of potentiometers, so there are magnets in the sticks.
A big question is which role the phone compass plays for the spark.

You can check this by going to RC calibration and waving a magnet over sticks you will see the little dot on screen moving as you move the magnet, because RC has magnets although small it is not recommended to use inside a vehicle where interference is likely.

See video below.

Watch this video it will show you magnets in RC.

hallmark007 Posted at 2017-12-11 07:43
Watch this video it will show you magnets in RC.

https://youtu.be/0h_lVR_gKMU

WOW!

!

This is very enlightening! Something that should be included in manuals in my opinion.

The big question:
Is it possible that magnetic disturbances around the RC (including one caused by a mobile device) could induce compass errors, yaw errors, IMU exceptions, fly aways, etc, etc.

ernie_halter Posted at 2017-12-11 09:18
This is very enlightening! Something that should be included in manuals in my opinion.

The big question:

No they can’t but if you look at the video they can cause involuntary stick movements causing aircraft to veer to a different direction than controller is commanding.

Ahmed Hussain Posted at 2017-12-11 08:52
WOW!

!

This was a fairly big magnet used, but it shows that interference can happen with RC if your standing or sitting in the wrong location, I don’t imagine it will be fatal but can cause slight unpredictable movement in aircraft.

Big lesson, thank you, i think every drone owner has to see this simple prove of magnetism on his equipment!

hallmark007 Posted at 2017-12-11 09:23
No they can’t but if you look at the video they can cause involuntary stick movements causing aircraft to veer to a different direction than controller is commanding.

So if I understand, to your knowledge having the DJI Go App display an incorrect heading of the RC / Pilot isn't as much a hazard as an annoyance, and isn't communicated with the Spark?

ernie_halter Posted at 2017-12-11 09:44
So if I understand, to your knowledge having the DJI Go App display an incorrect heading of the RC / Pilot isn't as much a hazard as an annoyance, and isn't communicated with the Spark?

Yes, you can always if triangle is off just lift aircraft up turn it and watch to see if App triangle is moving the same amount but when up in the air if you check triangle on little radar it should be on same heading as aircraft. I’ve been having same problem with one of my Crystalsky units driving me crazy trying to get it squared up.

Flying like yoda with two magnets...wow

What do you do if it's in the air and spark is straight and triangle is slightly off ? This is happening to me

fans209e8746 Posted at 2017-12-11 14:39
What do you do if it's in the air and spark is straight and triangle is slightly off ? This is happening to me

I think slightly off, like 5 degrees, may not be a big deal. If it's more I suggest calibrating the compass of your phone (waving it in a figure 8 pattern away from any metal, buildings, etc. while the remote is attached.

I just tried moving my iPhone around on top of the Spark RC, and moving Spark RC around on top of the iPhone with compass app opened. The compass on my iPhone does not seem to get interfered at all~~

hallmark007 Posted at 2017-12-11 09:26
This was a fairly big magnet used, but it shows that interference can happen with RC if your standing or sitting in the wrong location, I don’t imagine it will be fatal but can cause slight unpredictable movement in aircraft.

Before these amazing information, I was underestimating the low magnetic effects. Just because ignoring the RC magnet piece.

No more underestimating!

Interesting.  I had a scary disconnect (RC to the AC), thankfully GPS was not lost and return to home worked.  But i was in the middle of the field with ZERO issues and nothing nearby that had any magnets.  

Yea, from this point on, as an extra step on my checklist, I'll use an analog compass and orient the AC and myself toward magnetic north. Double check the info the GO app as well as the phone Compass app. I don't think the compass readings within the app can be trusted entirely since magnetic interference can be present without any warnings from the GO app.