UTD1000 User Manual
Select the FFT Window
Assuming the YT waveform is constantly repeating
itself, the Oscilloscope will carry out FFT conversion
of time record of a limited length. When this cycle is a
whole number, the YT waveform will have the same
amplitude at the start and finish. There is no waveform
interruption. However, if the YT waveform cycle is not a
whole number, there will be different amplitudes at the
start and finish, resulting in transient interruption of high
frequency at the connection point. In frequency domain,
this is known as leakage. To avoid leakage, multiply
the original waveform by one window function to set
the value at 0 for start and finish compulsively. For
application of the window function, please see the table
below :
FFT spectrum analysis
By using the FFT (Fast Fourier Transform) algorithm,
you can convert time domain signals (YT) into frequency
domain signals. With FFT, you can conveniently observe
the following types of signals :
● Measure the harmonic wave composition and
distortion of the system
● Demonstrate the noise characteristics of the DC
power
● Analyse oscillation
How to operate FFT functions
Signals with DC quantities or offset signals will cause
error or offset of FFT waveform quantities. To reduce
DC quantities, select “AC” coupling. To reduce random
noise and frequency aliasing resulted by repeated
or single pulse event, set the acquiring mode of your
Oscilloscope to “Average” acquisition.
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