Observing Aliases; Figure 2-2: Aliasing - Tektronix 2212 User Manual

Digital Storage Displays
Observing Aliases
in
Store MODE
2- 20
Aliasing
Aliasing occurs when the highest frequency component of the
input signal is greater than half the current sample rate. The
oscillocope cannot acquire the signal fast enough to construct an
accurate waveform record. Figure
2-2
illustrates this by showing a
slower aliased waveform on top of the actual input waveform.
Actual High-Frequency Waveform
Sampled Points
Apparent Low-Frequency Waveform
Due to Aliasing
Figure 2-2: Aliasing
In digital sampling, a more accurate reproduction of a signal is
possible when more samples of the signal are obtained. The instru-
ment samples 4000 times across the 10 horizontal divisions of the
graticule. This means that a sine wave spread across the full
screen will be sampled 4000 times.
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