Prearm: RC not calibrated


I just got all parts to build my first quadcopter (so of course I am a newbie :slight_smile:). I have a DJI F450 kit (with motors and ESCs), a pixhawk, 3DR GPS+compass and 3DR PPM sum encoder (v3). Radio is a Spektrum DX6i with a AR6210 receiver incl. satellite (that is why I am using the PPM sum encoder).

In the meantime the frame is ready, motors and ESCs mounted. So I connected the Pixhawk, flashed the firmware with MissionPlanner (v3.1.2) and also completed the wizard for first time setup.

But I cannot arm the quad, if prearm checks are enabled. It says RC not calibrated, despite the fact that I calibrated it several times. From another post I learned that min/max values could be the problem, but I do not know how to fix it.

Here are the calibration values:
Ch1: 1600-3007
Ch2: 1000-1403
Ch3: 991-1412
Ch4: 1600-2006
Ch5: 991-1413
Ch6: 1592-2014

The ranges seem a bit strange? In addition - if I deactivate prearm check RC - and arm the device, 2 motors do not spin even if I set throttle to max. Should not spin all motors even at low throttle?

I would appreciate any help!


In the meantime I did some experiments and found out that the problem arises from the PPM encoder. If I connect the satellite directly to the pixhawk everything is fine. I am able to calibrate the RC and also the motors spin as expected :slight_smile:

However, I like to use the main receiver (increased range). But I’ll move that question to the appropriate section.