Mavic 2 wants a compass calibration 30 days after last one

This morning my Mavic 2 Pro said it wanted a compass calibration. It wasn’t preventing the motors from being started. I couldn’t imagine why a calibration was being requested. But, I went ahead and calibrated anyway.

After looking at the .DATs it would seem that the reason was that it had been 30 days since the initial calibration. There were several of these today from the eventLog stream

-47.676 : 3918 [L-COMPASS][mag_cali_pt] date_from_last 30|

But, none in the eventLog stream from yesterday.

Also, the results of the calibration didn’t change significantly. From 30 days (2018-08-29, August has 31 days) the calibration gains and offsets

-35.448 : 4531 [L-COMPASS][scale cali(0)] estimation error:[15.0]
-35.448 : 4531 [L-COMPASS][scale cali(0)] succeed! bias:238.9 -148.1 -1314.6 scal:3.239 3.169 3.356|

From today after the calibration

-106.155 : 11073 [L-COMPASS][scale cali(0)] estimation error:[16.8]
-106.155 : 11073 [L-COMPASS][scale cali(0)] succeed! bias:235.1 -137.2 -1277.7 scal:3.210 3.154 3.280|

I received my M2 Pro very early. It’ll be interesting to see if others start to see their Mavic 2 requesting a calibration after 30 days.

Did you launch from the same spot you’ve flown several times before, or did you launch from a place you’ve never been before?

I got my M2P the same day as you. It hasn’t prompted me to calibrate the compass yet.

I actually calibrated my M2P 30 days ago. Maybe this doesn’t apply if you haven’t calibrated yet.

I calibrate every session I fly even if I don’t move and that’s why I’ve never lost any drones or ever had a compass error and I own 5 drones.

Different spots. All within 20 meters though. But, that’s not relevant here. The calibration request was because 30 days had elapsed since the last calibration.

@BudWalker, which version of DatCon are you using to read your DAT files?

I’m using 3.6.1. If you’re having trouble you may need to specify Invalid DatHeader OK.

I see this even when selecting DAT files I know contain flight data:


Two things. First, the DJI Assistant 2 for the Mavic 2 is different. Getting it to retrieve the .DAT involves a couple of extra steps. Second, it doesn’t matter since the Mavic 2 .DAT is encrypted.

So, we’re stuck with the tablet .DAT which often requires setting Invalid DatHeader OK.

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Yes, that’s of course the problem. I was trying to read the aircraft DATs. Thanks for the reminder! And thank you for your other message too.

Mavic 2 Pro I’m sure was on the first load out of China. Not seen any request for compass calibration.

A little soon to tell but it may be the case that the 30 day clock starts after the user has done a calibration.

This also happened to me, however, I discovered I was the problem. I live in FL where it’s not only hot, but humid thru October. Prior to a flight, I decided to set my camera settings by using a poster board “shelf” above my desk so the Mavic2 could “look out of the window”, and I would set my adjustments. I noted I kept getting a “calibrate compass” warning, but thought that would resolve when I got outside for takeoff. It didn’t. Then I realized one side of the poster board “shelf” I had placed my Mavic2 on rested on the base of my active wireless router.

I’m assuming that you left the M2 powered up while transporting it from the shelf to the launch site? If so, the Yaw would likely have been compromised because the M2 was powered on in a geomagentically distorted environment. But, the ‘calibrate compass’ request shouldn’t be necessary once it was away from the distortion…

No. I shut it down, as those camera setting tweaks were coincident w/Litchi’s M2 release, and I wanted to see if the M2 would work w/preprogrammed P4P “Missions”. I have a pretty good multi-band router, and the radiated energy just overwhelmed the magnetic balance. When I got the “calibrate compass” on the M2 startup, it took two horizontal turns (usually 1) before I got the vertical notification. I’ve not had any calibration issue since - albeit 30 days has not yet passed.

I suspect that the router and being inside on the shelf is unrelated to the calibration request. Radiated RF energy won’t magnetize M2 components. Any magnetic field surrounding the router would have to be very strong to magnetize M2 components. You could retrieve the table .DAT and we could take a look.

@BudWalker, I thought I calibrated the compass before my first flight. Unfortunately, I cannot find the DAT for the first flight. It looks like the mobile device might only store the last 10 or so DATs.

Here are the results from the compass calibration I did today:

78.325 : 4500 [L-COMPASS][scale cali(0)] fill num:[172]
78.325 : 4500 [L-COMPASS][scale cali(0)] estimation error:[11.5]
78.325 : 4500 [L-COMPASS][scale cali(0)] succeed! bias:25.2 -485.0 -833.2 scal:3.018 2.864 3.009|

78.325 : 4500 [L-COMPASS]mag cali pos and time saved success!

78.325 : 4500 [L-COMPASS][mag_cali_pt]height:207.1, date:20320216

Did you get a 2018 or 2032 date when you recalibrated?