Hi everyone,

My copter has the habit of pulsing the motors in loiter (and sometimes even in althold?), it seems like it wants to adjust its position but not very smooth, I really want a copter that can utilize the GPS properly because otherwise i don't really see a point behind the APM (although the MP is really cool). I am debugging this problem for a while now and still haven't found the problem,

I bought a new GPS + Compass combo and thought it would fix it but no, Exactly the same problem.

(first i had a compassmot around the 40%ish)

Tomorrow i will do another compassmot run and see if it has increased.

The things i still think that could be the problem:

1. old compassmot

2. Vibrations

3. processor power shortage? (read something about it somewhere, i am logging default + imu)

I also included a log of the flight today, tomorrow i will do another proper flight and record it)

I'd really like to hear your thoughts, I don't really know what to do anymore :)


Sorry for the bad English, I'm from The Netherlands

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Having a quick  look at your log, I can see that your vibration levels are well outside acceptable limits.  You should investigate how you can reduce them as a first step.

The Wiki has some useful hints here.  

There is also something very strange going on with your compass.  I'd recommend recalibrating it.

Whilst it's unlikely to be causing the issues you're having now, you should also investigate your GPS issue.  You had several issues with GPS lock during your flight.

As you've recently acquired the GPS+Compass, you should look at moving it well away from other electronics, ESC's and motors.  Placing it on a mast and recalibrating would help immensely, IMO.

Hi Matt,

Thanks for your really useful information,

I suspecten that the vibration could be the problem, I ordered an anti vibration platform off ebay and maybe that will do the trick.

Do you have any tips on re-calibrating my compass? I have watched the video from Randy mckay and did that but always ended up with more data needed. Then i was just on a quest to almost fully fill the sphere in MP and takes like 10 minutes but dont even know if its the right way,

The GPS problem is for another day, first i Will look at vibrations.

I did move the GPS+Compass 10cm above the mainframe so maybe it still needed to go higher?
(I'm flying a h-frame btw so the whole midsection is filled with esc's and wires.

I Will recalibrate it tomorrow and do something about the vibrations and then make another post.

Thanks a lot for your response!

Do you have any tips on re-calibrating my compass?

The only tip I have is to make sure you're facing North when you do the calibration.  I had the same challenges you did until I realised that I wasn't oriented correctly.

I did move the GPS+Compass 10cm above the mainframe so maybe it still needed to go higher?

Is the GPS in the shadow of large props?  You'll want to get it higher than the props which will probably interfere with the signal.

Good luck and let us know how you go!

Hi Matt,

I re calibrated my compass, did compass-mot again and went flying.

Also i updated to the latest 3.2 rc4 but don't know if that was a wise decision.

I forgot to read the compass interference number so i will do another compass-mot tonight.

The GPS is located above the props so I think that that should not be the problem.

I thought I had dealt with the vibration problem but I think I only made it worse. so i will do another attempt to reduce vibrations tonight.

I included 2 logs. in one log I test the loiter and the new poshold modes. but in that log the vibration values didn't get included so the other one is just flying in stabilize measuring the vibrations.

And i shot a video of the behavior in loiter. I would really appreciate if you could take a look at that.

Last question is, do i need to turn compass learn on or off? I have it off now but don't know if that is the best way to go

I really appreciate you help because I don't know it anymore :)


Video Link : http://youtu.be/0c2R9wzKcfM(I am running Hobbyking 30-amp ESC's flashed with simonk, don't know if it has anything to do with it but maybe could be sync issues? I don't know)


Hi Matt,

I just re-did compass calibration and here are the results.

I think i got 6%?

But i do have another question for which i should maybe slap myself in the head....

I have a brushless gimbal mounted on top of the quad. brusless motors = many magnets... duh -_-

maybe thats throwing off the whole compass situation. i'm not sure. I did compass calibration with the gimball powered.

First i will take another look at the vibration and then remove the gimbal and do another test flight.



Hi, I installed the vibration dampening mount and had another testflight.

In stabilize it flew amazing! it was really steady and flew a lot better than before.

But loiter though...

The pulsing part is kind of gone. the thing that its doing now is just toiletbowl for like half a circle and then just go left in a 30 degree angle orso.

Any idea's how to tackle this problem?


I attached a log, i can see that the GPS had some problems and thought its position was miiiles away. how can i fix that?

EDIT: I think that the new beta firmware wasn't a great idea, i will go back to 3.1.5 do the calibrations again and test again.


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