User Manual

94
UTD1000L
User Manual
FFT Spectrum Analysis
FFT Operation Tips
Select FFT Window
.
FFT (Fast Fourier Transform algorithm) mode can
convert time domain (YT) into Frequency domain
for signal waveform graph, which helps to easily
observe signals of following kinds:
Harmonic component and distortion in the
measurement system
Characterize noises in DC source
Analyze the virbration
Signals with DC components or bias may cause
error or deviation to FFT waveform components. In
order to reduce DC component, you can set
coupling to AC mode. And you can set ACQUIRE
type to AVG to lower down random noise or mixed
overlapped frequency component in repetitive or
single pulse event.
S
uppose YT waveforms repeats constantly and the
Oscilloscope then performs FFT on limited length
record. When the period numers are integer, YT
waveform at the start and finish points share same
amplitude values and will not cause any
interruption to the waveform. If it is non-integral,
the start and finish amplitude are different, and
high-frequency transient interruption will happen at
joint points, which is called leakage in frequency
domain. To avoid the leakage, FFT mode will
multiply original waveform with one window
function to force the start and finish values all go to
0. Refer to
following windows for details:
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