Strange INS FFT behaviour in Mission Planner

ArduCopter Copter 4.2
, ,
1

Hello,

I am currently setting up the notch filters of a 25 kg Copter running witch ArduCopter 4.2.3. For this purpose, I want to use the FFT tracking to automatically adjust the center frequencies of the harmonic notch filters. To observe the behaviour of the FFT tracking, I am looking at the FFT in Mission Planner, but it sometimes shows strange results. Sometimes there are magnitudes of the gyro signals in the range of -300 dB to -1500 dB. Another log resulted in a spectrum with large spikes pointing downwards:
Log29

Log31

Here is the link to the log files: WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free

I am currently using Mission Planner 1.3.77.1 build 1.3.8278.21251.

Any idea what causes this behaviour of the FFT?

2

Looks like a mission planner issue to me

3

That’s not what I see.

Gyro 29
Gyro 291246×957 66.2 KB

Gyro 31
Gyro 311253×949 65.3 KB

4

@dkemxr which MP version are you using?

5

Always latest Beta. Check the Magnitude box to get a scale that’s actually useful.

1 Like
6

@dkemxr Checking the magnitude box actually did the trick. Loading the logs without the box being checked still gives me weird graphs though, although I have the latest Beta version of MP.