Basic Operation
DSO1000B Series HandHeld Oscilloscope User Manual 22
The Math FFT function has three FFT Window options. There is a trade-off between frequency
resolution and amplitude accuracy for each type of window. You shall determine which one to
choose according to the object you want to measure and the source signal characteristics.
Special-purpose window applicable to discontinuous
waveforms. This is actually the same as no windows.
5.3.1.4 FFT Aliasing
Problems occur when the time-domain waveform acquired by the oscilloscope contains frequency
components higher than the Nyquist frequency. The frequency components above the Nyquist
frequency will be undersampled and displayed as lower frequency components that ‘fold back’
from the Nyquist frequency. These erroneous components are called aliases.
5.3.1.5 Eliminating Aliases
To eliminate aliases, use the following methods.
Click the TIME/DIV key to set a faster sample rate. Because the Nyquist frequency increases
as you increase the sample rate, the aliased frequency components will be displayed correct.
If too many frequency components appear on the screen, you may use the FFT Zoom option
to magnify the FFT spectrum.
If there is no need to observe the frequency components above 20MHz, set the Bandwidth
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