FFT (Fast Fourier Transform) is a useful tool to analyze the frequencies present in the sound. The figure shows frequency on the x-axis and amplitude on the y-axis.
You can change the scale of the x-axis to logarithmic, linear, or to display note names just by highlight the LOG, LIN or ST buttons. The curve can be locked by tapping the “Spectrum(FFT)”.
MF button is highlighted by default, which means that the display shows frequency from 100Hz-1KHz (medium frequency area). You can switch FFT Tuning Unit to show frequencies between 10Hz-10KHz by tapping the MF button again.
For example, the detected note is F#3 showing on the screen, while F# means the note and 3 means the octave. The detected frequency is 184.8 Hz, and the cent value is 2.2 cent. The vertical line on the screen indicates the position of the detected note on the spectrum.