Frequency Bin

Definition

The frequency range and resolution on the frequency axis of a spectrum graph depends on the sampling rate and the size of the data record (the number of acquisition points). The number of frequency points or lines or bands in the power spectrum is N_RECORD/2, where N_RECORD is the number of signal points captured in the time domain.

The first frequency line in the power spectrum always represents DC (frequency=0). The last frequency line can be found at f_SAMPLE/2 - f_SAMPLE/N_RECORD. Frequency lines are spaced at even intervals of f_SAMPLE/N_RECORD. They are commonly referred to as frequency bins or FFT bins. Bins can also be computed with reference to a data converter's sampling period:

Bin = f_SAMPLE/N_RECORD = 1/(N_RECORD × Δt_SAMPLE)

Example: We apply a sampling frequency of 82MHz and take 8192 records. The frequency bin is 10kHz.