FFT Amp Spectrum (dB)
The amplitude spectrum is calculated using a split-radix real FFT. If the number of acquired points is not a power of two, zeros are padded at the end of the waveform so it is the next higher power of two. The FFT is scaled to decibels:
dB[i] = 20.0 × log10 (Amplitude[i] / Peak Amplitude)
Units
Decibels relative to peak
X Units
hertz
Resulting Array Size
Next higher power of two than the inputSize divided by two.