Hello Everyone,
I would like to type you my experience and solution with Bad AHRS and Error Compass Variance. For almost 2 weeks i was trying to find solution on this for our X8 Aerial Mapping Quad and i had zero to no success, so this is what i did and stopped having any issue since then.
Our Pixhawk is not 3DR but its a version of it designed and manufactured in the Balkans, with a size approximatly 2/3 of the 3DR version.
a) Reformat and uploaded again the X8 configuration
b) sealed the pixhawk underside and sides with Kyosho Receiver Seal film also almost half the top side
c) Changed the Kyosho Silicone double sided tape with 3M 3mm Foam
d) made sure my telemetry was 10cm away from pixhawk and also sealed with Kyosho receiver tape.
e) Turned on radio and X8 and programmed correct compass orientation as also for the X8 to use only external compass
f) before all the above i programmed my M8N (i used the Walkera BN330 M8N of the Voyager) with the 3DR configuration file.
g) Radio Calibration/Speedo Calibration
h) Speedo/Compass calibration with correct rotation props, from zero to full throttle for more than 30 seconds and full AMP load.
i)NOW i run compass calibration with autosave
As soon as i did the above, my bad AHRS was gone and also the compass varience problem.
Since them we have done tests with up to 50Km winds and the X8 being at a steady 45amp draw and as solid as a rock. We have had telemetry with mission planner on and open window for EKF and all levels are pretty low and Green, we have not even had orange. With M8N we have average 17sats.
Last but not least is that on Vibe window with see all Green on all 3 axis and maximum values have been 1/3 up from zero to first red line.
Hope this post helps some of you.