Set up the RPM filter (bidirectional DShot)
The RPM filter is the most effective motor-noise filter — but only if the RPM telemetry runs cleanly. Here's how to enable it correctly and check that it actually works.
01Enable bidirectional DShot
The RPM filter needs the actual motor RPM from the ESCs. In the motors tab, enable bidirectional DShot (requires DShot-capable ESCs with suitable firmware). Without this telemetry there is no RPM filter.
02Set the motor pole count correctly
Enter the correct number of motor poles (14 for most FPV motors). A wrong value makes the RPM telemetry — and therefore the notch frequencies — land in the wrong place.
03Enable the RPM filter and check eRPM
With bidirectional DShot active, Betaflight enables the RPM filter automatically. In the motors tab, check that all four motors report a plausible RPM/eRPM value — if one drops to 0 or jitters, the telemetry is faulty.
04Confirm the effect in the log
Whether the RPM filter actually removes the motor harmonics is only shown by the FFT. PIDoctor overlays the motor harmonics on the spectrum and checks whether the RPM filter and dynamic notch really attenuate them — or whether some get through.