External Compass Calibration

I have an issue with my external compass.
I have cut the internal compass of the apm 2.5 and connected an external compass.
The calibration process worked but I do have a strange behaviour of the compass.



a) if I move the compass it is moving towards the wrong direction, the reason for this can be that I have to flip it around I do not understand how to configure the compass orientation - any ideas?
b) the reaction of the compass is very slow, it reacts with a very strange delay
c) if I move the apm and not the external compass, the compass in mission planner moves - btw very fast. But it should not move because I have disconned the internal compass. Is this normal?
d) the north is not correct - how can I setup this,

Could it be that this is an issue because I do not have a GPS signal? The reason for that is that I was inside of my house.

Many thanks

I have found a solution - even without understanding how APM works internally.
I have installed the GPS together with the APM in the plane. Than I have done the calibration process outside with working GPS connection.
It took me a while to adjust the Compass Orientation but after same attemps I ended up with ROTATION_PITCH and everything was fine.

The plane reacts immediate on any changes in the right order.
I am still interested in the logic behind, but for the moment I am happy. :smiley: