Keysight InfiniiVision DSOX1204A - Page 58

58 Keysight InfiniiVision DSOX1204A/G Oscilloscopes User's Guide
2 Quick Reference
So, in practice, an oscilloscope's sample rate should be four or more times its
bandwidth: f
S
= 4f
BW
. This way, there is less aliasing, and aliased frequency
components have a greater amount of attenuation.
See Also Evaluating Oscilloscope Sample Rates vs. Sampling Fidelity: How to Make the
Most Accurate Digital Measurements, Keysight Application Note 1587
(http://literature.cdn.keysight.com/litweb/pdf/5989-5732EN.pdf)
Oscilloscope Rise Time
Closely related to an oscilloscope's bandwidth specification is its rise time
specification. Oscilloscopes with a Gaussian-type frequency response have an
approximate rise time of 0.35/f
BW
based on a 10% to 90% criterion.
An oscilloscope's rise time is not the fastest edge speed that the oscilloscope can
accurately measure. It is the fastest edge speed the oscilloscope can possibly
produce.
Figure 5 Sample Rate and Oscilloscope Bandwidth
Limiting oscilloscope bandwidth (f
BW
) to 1/4 the sample rate (f
S
/4)
reduces frequency components above the Nyquist frequency (f
N).
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