Bad Ahrs problem

I have a Pixhawk 2 with externel Radiolink GPS/compass running Arduplane 3.8.5 now.
Everything works fine and all calibrations were successful…
After a while however the ahrs starts drifting and jumping an I am getting bad ahrs all the time but it still seems to work.
Sometimes also the compass starts drifting.
I have reloaded firmware a number of times (also older versions) and re-calibrated several times successfully but the drifting returns.
Also the Pixhawk sometimes will not start at all and have to disconnect power (sometimes 2-3 times) to get it going.

It feels like bad hardware to me.

Any ideas ?


Usually, that is a bad calibration. Did you calibrate outdoors, on a level surface with no magnetic interference ?

I disabled the internal ahrs and recalibrated outside.
Stable now.

One more question.
Mavlink is working great but I cannot find what the HUD shows.
There are little green vertical bars and I assume this is signal strength ?
Then there is a percentage which is supposed to be % of bad packets. Most of the time it reads 99% and may sometimes vary to 90.
The link is perfect at 99 % errors ???
It does seem the inverse to me : % correct packets.
Is this correct?


AHRS is bad indoors when you have a lot of jumping of the GPS. The percentage is of good packets – not bad. Think of it kind of like a signal quality.