ESC telemetry based notch filter setting

nerakai · October 5, 2025, 3:53pm

Hi guys,

I’m trying to set up notch filter for my 15inch quad copter.

FC is micoair743v2

ESCs are bidirectional Bluejay dshot so I decided to go with ESC telemetry notch filtering for the first time.

Motors : Tarot MT4008 kv330

Props : 15inch foldable

Battery : 6s Liion 8000mah (960g)

Flight log

I tried to find out what value should go in the INS_HNTCH_FREQ, BW but am not really sure whether 50 and 30 are right values for them.

Is INS_HNTCH_FREQ possible to be found out in the graph or do I need to somehow calculate it utilizing ESC RPM average? If it were throttle based notch, I would confidently put 55 in there but is it same when it is ESC telemetry based notch?

Also, why do I see that many harmonics in the graph? Does it indicate any vibration on frame or arms? Do I need set up 2nd/3rd harmonics or use second notch filter in this case?

I’d appreciate if anyone can give me an example notch setting for my copter based on the log file. I’m planning to apply mutisource and update at loop rate option later if it is OK and practical to do so.

Thank you for taking the time to read and explain this. Also, any suggestion to improve the system is welcomed.

dkemxr · October 5, 2025, 10:05pm

Use Estimated Post Filter. Check the Show Notch 1 box. Does the notch band align with the peaks? No? Why not? Perhaps the default Pole number for those motors is not correct?

nerakai · October 7, 2025, 9:26am

Thanks for your advice.

I found pole number was 18 so I adjusted the param and flied it once again after reseting notch params into default.

Flight LOG

After changing pole number into 18, it still didn’t show much different graph. I can’t tell notch band align with peaks for sure.

Is there any part I missed?

nerakai · October 7, 2025, 9:49am

or Is this better than the previous setting? The graph seems almost same.

dkemxr · October 7, 2025, 12:23pm

That’s not what I found.
Motor pole number: 24P

nerakai · October 7, 2025, 12:31pm

Sorry, It seems I got it completely wrong. I counted something right next to the coil not the magnets on motor cap. Yes, there were 24 poles when I just counted.

Thanks for pointing it out. I will give it a try again.

dkemxr · October 7, 2025, 12:37pm

Instead of batch logging use Raw Log for that flight controller. It has an Sd card right? If not keep it configured as you have it.

set these:
INS_LOG_BAT_MASK,0
INS_LOG_BAT_OPT,0
INS_RAW_LOG_OPT,9

nerakai · October 7, 2025, 12:40pm

Thank you. I will fly it again after reseting notch params and those 3 params tomorrow.

Yes, there is a SD card.

nerakai · October 8, 2025, 12:11pm

I had a test flight with those params set as you asked to.

Flight log

Thanks for your time.

dkemxr · October 9, 2025, 12:34am

This looks effective with estimated post-filter. Give it a fly and check it out.

nerakai · October 9, 2025, 12:16pm

Hi dkemxr,

Here is the Flight log with the notch setting you adviced.

To me, the graph seems great with all peaks lower than -60.

What do you think of the result?

I wasn’t even aware of the parameter ins_raw_log_opt until now. Learning everyday!

amilcarlucas · October 9, 2025, 12:54pm

If you would have used ArduPilot methodic configurator software that and 80 more parameters would have been automatically set to their optimal values. And you would have been guided step by step in configuring just the other 200 required for safe flight while never seeing the remaining 1000 parameters that are irrelevant for you.

nerakai · October 9, 2025, 1:17pm

I actually tried few days ago with the configurator software and had to stop not long after beginning as I was not sure about my hardware specs and afraid of putting wrong information in there.

This parameter is going to be saved for future reference and I’m thinking of restarting from the scratch using the configurator tool. Copter is throwing a couple of errors now. It settles down in about a minute or two but it needs compass calibration after replacing battery, Need position error for a while after reboot until it changes IMU. Even after settling down and gets ready to arm in loiter, now it won’t allow quik-tune which was loaded in script initially. I can only guess it might be interference issue and it is finally the time for me to try Magfit which I always have been avoiding last few years.

dkemxr · October 9, 2025, 3:45pm

Looks good! Disable Raw Logging once the filter parameters are set or you will have some huge log files.

And BTW-That is only useful on higher performance processors (H743, etc) with a Sd card. Slow dog’s like F405’s, all SpeedyBee’s for example, will choke.