Question on Taking FFT log for notch filter frequency

ArduCopter
1

While reading about taking the FFT log to determine the vibration frequency, I ran across this paragraph:

To get a notch filter setup you need to hover your vehicle for at least 30 seconds with no pilot input and with [INS_LOG_BAT_MASK]set to 1. This will enable FFT logging which will guide the correct setup of the notch filters.

I am assuming this 30 second hovering can’t be done with loiter mode? I don’t think my little 3" quad will stay reasonably still for 30 seconds without me trying to pull it back. Is there a way to keep it still for 30 seconds?

2

You can set:
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4
and hover in AltHold or Loiter.
Stabilise is a useful mode to practice in too since it could be needed in emergencies

1 Like
3

Appreciate the response! I will give that a try!
I can fly in stabilized without issues (been flying in Betaflight for a while). But it’s just near impossible to keep a 3" quadcopter still without touching any controls. They seem to want to drift no matter what!

Thanks again!

4

It’s not critical to ONLY hover, some amount of movements are fine.
If you go ballistic then the FFT graphs will be poluted with a mess of frequencies.