Hi,

Today, after the takeoff of my SPARK with GPS e everything working fine,  GJI GO sent a message "Magnetic Field Interference. Exit P-GPS Mode", and "Weak GPS Signal.......", and went to ATTI mode. After that it starts drifting away with the wind. Luckily, It was about 37 meter height and 51 meters distance, and I could see it and bring back. After some seconds (looks like one hour for me) he recovered its GPS and I could land. I did calibrate the compass one week ago in this same place. Does anyone know how can I avoid this to happen again? I almost lost my drone......

if you place the drone on top of a concrete block, the mobile will indicate compass error...there is no need to calibrate...just move away far away from the interference and you will see the message gone...

There are ways to insure your compass is good before take off. One is to check when turned on that small red triangle bottom left hand corner it should be pointing on the same heading as your aircraft.

If your app asks you to calibrate or move spark, always move and start up procedure again.

Why would you calibrate ?
Your manual clearly tells not to calibrate unless prompted, you almost never will have to calibrate your compass, so if you have a perfectly good working compass how would calibration make it better? But there is a good chance you could make it worse.

Calibration gives the compass the information it needs to determine which magnetic influences are part of the Spark and what is the earth's normal magnetic field.
The compass doesn't lose calibration and doesn't ever need re-calibration unless you add or remove equipment to/from the Spark



Avoid Compass Crash.

Tip To Help Avoid compass interference and crash.
1/ Never calibrate Compass unless prompted to.

2/ start AC leave until you receive enough gps lock ,

3/ if you get Compass interference turn off AC and move to another location,
without interference.

4/ In bottom left hand corner on your map you will see small red triangle, check to make sure that this triangle is pointing in the same direction (heading) as your AC, this will show good compass on the ground.



Raise AC to height of 8ft
Hover for 20 seconds
Fly forward 2ft
Backward 2ft
Left 2ft
Right 2ft
Up 2ft
Down 2ft
Yaw left
Yaw right
Each time returning to hover position
If you have a good horizontal each time, you will then know you have good gps good IMU and good Compass, and your ready to fly.

This exercise takes less than 2 minutes and is worthwhile doing before every flight,

S.J Posted at 2017-12-9 10:37
if you place the drone on top of a concrete block, the mobile will indicate compass error...there is no need to calibrate...just move away far away from the interference and you will see the message gone...

Hi. The compass problem happened with the drone in the air. It was far away from any concrete block....

djiuser_7DCDCMv Posted at 2017-12-9 12:12
Hi. The compass problem happened with the drone in the air. It was far away from any concrete block....

You can often pick up compass problem on the ground it may not manifest itself until it’s in the air, that’s why I recommend doing a proper preflight checks.

hallmark007 Posted at 2017-12-9 10:56
There are ways to insure your compass is good before take off. One is to check when turned on that small red triangle bottom left hand corner it should be pointing on the same heading as your aircraft.

If your app asks you to calibrate or move spark, always move and start up procedure again.

Hi hallmark007.

I did check the positioning of the triangle before takeoff and it was according to the drone.  Another information is that, after landing the dji app prompted a message to calibrate the compass.

My understanding was that it would be good to calibrate before takeoff.

Another question, I never calibrated the IMU. Should I do that?

djiuser_7DCDCMv Posted at 2017-12-9 12:21
Hi hallmark007.

I did check the positioning of the triangle before takeoff and it was according to the drone.  Another information is that, after landing the dji app prompted a message to calibrate the compass.

Unless you have a problem no need to calibrate IMU again your app will tell you.

Usually when asked to calibrate compass it will come with message calibrate or move aircraft. Always move Aircraft , never calibrate in the area you get the message, this should be explained more in the manual but it’s not, don’t know why.

hallmark007 Posted at 2017-12-9 12:46
Unless you have a problem no need to calibrate IMU again your app will tell you.

Usually when asked to calibrate compass it will come with message calibrate or move aircraft. Always move Aircraft , never calibrate in the area you get the message, this should be explained more in the manual but it’s not, don’t know why.

Ok, thank you for the help!

Hmmm...  My backyard is about 100 yards from high voltage power lines. Never had a problem though I stay 100 yards away. But interference is everywhere. Fly close, and test areas around your fly zone. I picked up a OTG adapter today. I wanna check the difference between hardwired and wifi signal action. Cheers

Suggest you use OTG cable if you are on IOS mobile.. Dont try on an Android..

Regarding compass errors or IMU calibration  , it is better first  understand the instructions thoroughly to cablibrate the compass and IMU before practicing it on the drone !!

S.J Posted at 2017-12-9 21:14
Suggest you use OTG cable if you are on IOS mobile.. Dont try on an Android..

Hi, I'm using OTG cable and my mobile is running Android. By the way, my mobile doesn't have compass.

Hi, I just received the email instruction from DJI support:

Dear Luis,

Thank you for contacting DJI Technical Support. We understand that you suddenly received magnetic field interference and weak GPS signal error with your Spark. Don't worry as we will do our best to help you with this concern.

In this case, may we ask if you are using the latest firmware version for both your aircraft and remote controller? Before this issue happened, did you had an update on your drone or DJI Go App? We suggest that you do IMU and Compass Calibration again to make sure that everything is working fine before flying your drone.

Compass Calibration:
1. Choose an open area to conduct the compass calibration.        
2. Tap the Aircraft Status bar in the app and select "Calibrate", then follow the on-screen instructions.        
3. Hold the aircraft horizontally and rotate 360 degrees. The aircraft status indicators will go solid green.        
4. Hold the aircraft vertically with the nose pointing downward, and rotate it 360 degrees around the center axis.        
5. Recalibrate the aircraft if the status indicators blink red.        
If the status indicators blink red and yellow after the calibration procedure, move your aircraft to a different location and try again.        

IMU Calibration:
1. Make sure that the Aircraft and Remote Controller battery is more than 50%.  
2. Turn on Remote Controller and connect to the Mobile Device.  
3. Place the Aircraft on a level surface.  
4. Turn on the Aircraft.      
5. Launch DJI Go app and go to Main Controller settings > Advanced Settings> Sensors> IMU Calibration> Start Calibration.  
6. The calibration process will take about 5 minutes. Please wait for the confirmation on DJI Go app.  
7. IMU Calibration will fail if the aircraft is not positioned according to the instruction on DJI GO app.  
8. If calibration fails, restart the aircraft and calibrate the IMU again.  

Also, please do try to re-link your remote controller and your aircraft to make sure that they both have a fresh connection again. Please do follow the guide below.

Linking the Remote Controller:        
1. Power on the aircraft and the remote controller. Wait until the aircraft status indicators blink yellow. Ensure that the remote controller is within 20 cm of the aircraft during linking.        
2. Press and hold the power button of the Intelligent Flight Battery for three seconds. Release the button after hearing a single beep. The Front LEDs will blink red.        
3. Press and hold the Flight Pause button, the Function button, and the Customizable button simultaneously.        
Linking begins when the alarm becomes a quick single beep after an alternating single/double beep.        
4. Then the front LEDs turn solid red after blinking green. When the status LED on the remote controller turns solid green, linking is complete.        

We will be waiting for your response.
Thank you and may you have a nice day.
Thank you for supporting DJI.

Hi,

This is the Flight Record of when I had the problem. Can anyone analyze it?

http://phantomhelp.com/logviewer/8WMJ4PV538G93FFWO43N/