No stable ground course possible?

what is the reason that the black course line ( ground course ) is changing its direction frequently ?
i have made a setup with pixhawk and Neo M8p Module ( Drotek RTK XL ). Calibration went well,
only external Compass is on, GPS 3D Fix, HDOP 0.98… any advice please ?


I’m seeing the exact same thing.
Is it a problem?
What can it effect?

The Black GPS track line keeps changing.

I’ve been studying arducopter 3.4.4 for months
and also wondering what IYAW in KNF3 is?
I see edges as if it’s processed it’s changed heading…
but it wasn’t!