4.Advanced User Guidebook
24
Rectangle
Best solution for frequency, worst for magnitude.
Best type for measuring the frequency spectrum of
nonrepetitive signals and measuring frequency
components near DC.
Recommend to use for:
Transients or bursts, the signal level before and
after the event are nearly equal.
Equal-amplitude sine waves with frequencies
those are very close.
Broadband random noise with a relatively slow
varying spectrum.
Blackman
Best solution for magnitude, worst for frequency.
Recommend to use for:
Single frequency waveforms, to find higher
order harmonics.
Hanning
Good for magnitude, but poorer frequency
resolution than Hamming.
Recommend to use for:
Sine, periodic and narrow band random noise.
Transients or bursts where the signal levels
before and after the event are significantly
different.
Kaiser
The frequency resolution when using the Kaiser
window is fair; the spectral leakage and amplitude
accuracy are both good.
The Kaiser window is best used when frequencies
are very close to the same value but have widely
differing amplitudes (the side lobe level and shape
factor are closest to the traditional Gaussian RBW).
This window is also good for random signals.
Bartlett
The Bartlett window is a slightly narrower variant
of the triangular window, with zero weight at both
ends.
Notes for using FFT
Use the default
dB
scale for details of multiple frequencies, even if they have very
different amplitudes. Use the
Vrms
scale to compare frequencies.
