Compass error during flight

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Hi,

I lost my P4 tuesday, after a message of Compass error, exit GPS mode, and it switch to ATTI.

After that, the aircraft was disconnected, and nothing...

I need help to know what my drone did at this time, if it drift during the battery Life, or it just landed...

Thank you
 
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Hi,

I lost my P4 tuesday, after a message of Compass error, exit GPS mode, and it switch to ATTI.

After that, the aircraft was disconnected, and nothing...

I need help to know what my drone did at this time, if it drift during the battery Life, or it just landed...

Thank you
Bobby, the answers may be somewhere within your flight log. Go here DJI Flight Log Viewer | Phantom Help and follow the instructions for uploading the flight log from your mobile device. Post a link to the viewer back on this thread. There are several members who can decipher a lot of the information. DJI Flight Log Viewer | Phantom Help
 
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Compass errors are caused by taking off over metal or flying too close to metal objects. We need the flight records to know for sure.
 
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I had a P4P that gave me lots of compass errors and entered ATTI (fixed it with degaussing), but I never lost connection with the AC when that happened. Compass errors are not uncommon, but it rarely causes lost connection.
What did you do when you got the error message?
 
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I had a P4P that gave me lots of compass errors and entered ATTI (fixed it with degaussing), but I never lost connection with the AC when that happened. Compass errors are not uncommon, but it rarely causes lost connection.
What did you do when you got the error message?
I hit RTH and after I lost connection...
 

Fly Dawg

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After the switch to ATTI at ~29 seconds,you continued to give forward elevator flying the aircraft farther away from you. You lost signal ~20 seconds later. There is no way to know what occurred after that without the aircraft data file itself.
Capture.PNG
 

Fly Dawg

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@~99 seconds you issued go home. It appeared to be responding, but the compass error came back and the aircraft re-switched to ATTI and began drifting until the end of the data.

Capture2.PNG
 

sar104

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After the switch to ATTI at ~29 seconds,you continued to give forward elevator flying the aircraft farther away from you. You lost signal ~20 seconds later. There is no way to know what occurred after that without the aircraft data file itself.View attachment 110772
Actually we can do a lot better than that. The ATTI mode drift was pretty consistent at the end and so provided that it stayed in ATTI mode (that generally happens), we can extrapolate the battery level down to the SMART_BATTERY_landBattery level, and extrapolate distance and track to a predicted land point. The downside is that the connection was lost at 88% battery, and so there was a lot of battery left for the ATTI mode drift.

The result looks like this, with autoland starting at point C and finishing at point D. That gives a total distance from the launch point of around 4795 m on a bearing of 130°.

110775


110774


I'm reluctant to put much of an error estimate on that, but it could be several hundred meters in range and direction.
 

Fly Dawg

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@sar104 You quoted the first post #7 , prior to the remaining data in Post#8. You are correct however in your statements in Post #9. Just clarifying. The aircraft drifted quite a long way by calculations. Many distractions around here today, so probably not the best time for data analysis for me. ( Disclaimer for a few mistakes today of my own making )......
 

sar104

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@sar104 You quoted the first post #7 , prior to the remaining data in Post#8. You are correct however in your statements in Post #9. Just clarifying. The aircraft drifted quite a long way by calculations. Many distractions around here today, so probably not the best time for data analysis for me. ( Disclaimer for a few mistakes today of my own making )......
Sorry - I should have been clearer. When I said that we could do better I was referring to your comment that there was no way to know what occurred after the lost connection, not to your presentation of the data.
 

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there is the link of the Flight Log
Your Phantom was warning you of problems early in the flight at 12.8 seconds with compass error messages.
At 27.8 secs, while the drone was still only 70 feet away, that changed to yaw error which is more serious and should have been a warning to end the flight.
Continuing after those warnings was not safe.

You would have to look at your launch point for the cause.
You've launched from somewhere that had magnetic distortion that caused the drone to get a false indication of where north is.
The usual cause is launching from somewhere very close to something steel and reinforced concrete is the most common but also things like wooden decks with bolts just under the launch position.
 
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What did you use to degaussing your P4P and how did you do it?
Demagnetizing the whole drone sounds weird, there are motors with their magnets...
So?
I degaussed with a degaussing device called cfixer (specially made for dji drones) and followed the instructions. Only the compasses need degaussing, by holding the cfixer close to them, they are located inside the legs. It worked for me, no compass errors anymore, except when I try to take off close to metal objects.
 
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I degaussed with a degaussing device called cfixer (specially made for dji drones) and followed the instructions. Only the compasses need degaussing, by holding the cfixer close to them, they are located inside the legs. It worked for me, no compass errors anymore, except when I try to take off close to metal objects.
Thanks, is it this one?
 

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Thanks, is it this one?
I degaussed with a degaussing device called cfixer (specially made for dji drones) and followed the instructions. Only the compasses need degaussing, by holding the cfixer close to them, they are located inside the legs. It worked for me, no compass errors anymore, except when I try to take off close to metal objects.
Probably a lot cheaper chinese device, like this Demagnetizer, is able to do the same task, just without the possibility to do it in the field, if you do not have the Main AC power supply, without the battery supply.
Usually should be enough to do it one time, at home/office.

€ 11,07 31%OFF | Watch Demagnetizer Is Not Allowed To Adjust The Mechanical Watch Time and Speed Watch Degaussing Device
 
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Thanks, is it this one?
Yes, that's the one. I guess my P4P had been stored close to some magnets, it was purchased from a shop that also sell speakers and other electronic stuff. Speakers have very strong magnets. I got comapss errors from the first flight. Others have also reported that cfixer fixed the errors.
First I used cfixer as instructed, then I performed two calibrations on the aircraft - in a field with no metal underground, no metal objects on me (watch, cellphone etc.). Since then my P4P has flown perfect! :)
 
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Yes, that's the one. I guess my P4P had been stored close to some magnets, it was purchased from a shop that also sell speakers and other electronic stuff. Speakers have very strong magnets. I got comapss errors from the first flight. Others have also reported that cfixer fixed the errors.
First I used cfixer as instructed, then I performed two calibrations on the aircraft - in a field with no metal underground, no metal objects on me (watch, cellphone etc.). Since then my P4P has flown perfect! :)
yes, I have understood all, ok, but as I also commented in the video in Youtube to be 100% sure of having the drone in an open field far from any hidden metallic materials, we should test it first with a professional metal detector, otherwise you can just hope to be in a clean area.
 

sar104

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Probably a lot cheaper chinese device, like this Demagnetizer, is able to do the same task, just without the possibility to do it in the field, if you do not have the Main AC power supply, without the battery supply.
Usually should be enough to do it one time, at home/office.

€ 11,07 31%OFF | Watch Demagnetizer Is Not Allowed To Adjust The Mechanical Watch Time and Speed Watch Degaussing Device
You can get those on Amazon too - I have one and they work fine.

Watch Demagnetizer, Watch Repair Screwdriver Tweezers, Mechanical/Quartz…
 
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You can get those on Amazon too - I have one and they work fine.

Watch Demagnetizer, Watch Repair Screwdriver Tweezers, Mechanical/Quartz…
thanks, I have seen it, but it's not convenient for me in Italy, it would cost me twice as much with shipping and importing, no sense.
I already bought it in AliExpress, chose AliExpress standard shipping, and only paid 12.26 € with an additional compass, no other additional expense, I will probably receive it in 3 weeks, I am in no hurry to have it.
 

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