How to read a Betaflight blackbox log
A blackbox log is your quad's flight recorder. Understanding the key traces lets you judge a tune objectively — instead of going purely by feel.
What's in the log
A log records, per axis, the gyro (filtered and, in debug mode, unfiltered), the setpoint (your commanded target), the individual PID terms, the motor outputs and the RC inputs. Every tuning problem can be reconstructed from this raw data.
Setpoint vs. gyro: the tracking view
The single most useful view is how well the gyro (actual) follows the setpoint (commanded). Overlay the two and any lag, overshoot or ringing tells you whether P, D and feedforward are right. This is exactly what the step response is computed from.
The FFT: where the noise lives
The gyro's frequency spectrum (FFT) reveals noise peaks — usually motor harmonics that move with throttle. Overlay the filter cutoffs and you can see whether the filters actually cut where the noise sits.
Let PIDoctor read it for you
Instead of interpreting everything by hand, PIDoctor computes the step response, FFT and a tune score automatically and turns the findings into concrete CLI commands. Upload your log and you get the diagnosis in seconds.