PeakTech 1280 Bedienungsanleitung Seite 94

15.1. To select the FFT window
There are four FFT windows. Each one has trade-offs between frequency resolution and magnitude
accuracy.
Type
Hamming
Rectangle
Blackman
Hanning
Characteristics
Better solution for
Rectangle, and good for frequency as well. It
has slightly better frequency resolution than
Hanning.
Recommend to use for:
Hamming
 Sine, periodic and narrow band random
noise.
 Transients or bursts where the signal
levels before and after the event are
significantly different
Best solution for frequency, worst for
magnitude.
Best type for measuring the frequency
spectrum of non repetitive 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
frequencies those are very close.
 Broadband random noise with a relatively
slow varying spectrum
Best solution for magnitude, worst for
frequency.
Recommend to use for:
Blackman
 Single frequency waveforms, to find higher
order harmonics.
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.
magnitude than
sine waves with
-94-
Window