The Letus Helix iOS app (available on the App Store) now comes with a Set Notch Filters tool to get rid of buzzing. This tool can be accessed by going to the Set PID and Power Values screen and then to the Filters screen of the app. Many times this tool is sufficient to get rid of minor buzzing by itself, although sometimes more significant measures (PID changes) must be taken. Start by setting notch filters.
Using the Set Notch Filters Tool
Turn on the Helix and connect to the Helix using the wifi. The password is 77777777.
Press the Connect button in the app to connect to the Helix.
Make sure the motors are on. If they aren’t on, press the menu button once to turn them on.
Go to the Set PID and Power Values screen.
Go to the Filters screen.
Press the Set Notch Filters button.
Grab the tilt handle with your right hand and steady it.
Press the Okay button with your left hand.
Pick up the Helix and put it into a position that causes it to buzz. You have 6 seconds to get it to buzz audibly and it must buzz for at least 2 of those 6 seconds for the app to detect and filter out that buzzing.
If you still have buzzing, you can repeat steps 6-9. The app can set up to 3 notch filters.
If, after setting 3 notch filters, you still have buzzing, then you will need to fine tune the PID settings on the axis that is buzzing. See below for instructions
Using PID settings to eliminate buzzing
Determine the axis that is buzzing. If this is not obvious (sometimes it is not), then
Go to the Set Power screen.
Write down the Power settings for each axis.
Turn the power on the tilt axis to 0. Press the Write button.
See if it is still buzzing. If not, then the buzzing axis is the tilt axis. Skip step 5 and go to step 6.
If it is still buzzing, then set the pan axis power to 0 and press the Write button. If the buzzing stops, then the buzzing is on the pan axis. If it does not stop, then the buzzing is on the roll axis.
Return the power settings for each axis to the original settings and press the Write button.
Go to the Manual Adjustment Screen (It is an option on the Set PID and Power screen).
Select the axis that is buzzing.
Lower the D value by 10 for non-encoded Helixes or by 20 for encoded Helixes (use 10 if not sure). Press the Write button.
Go back to the Set Filters screen and Press the Clear Notch Filters button.
Use the Set Notch Filters tool again.
You may repeat this cycle a few times as necessary, but do not lower your D value any more than is necessary, as you may develop wobbly or shaky footage.