HP 54710A User's Reference Manual page 30

How the Oscilloscope Works
Sampling Overview
Figure 1-4 shows the same 489-ps pulse sampled at 2 GSa/s. Notice that ten
acquisitions were taken again. This time you have a better sense of what the
signal looks like. However, there are still enough differences among each of
the ten waveforms that you can say the signal is undersampled. Notice that
figure 1-4 gives you more information about the signal than figure 1-3. The
oscilloscope has enough data to make the measurements, but the statistics
results show that there is a wide variation in the measurement results.
Figure 1-4
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