Agilent Technologies 3000 Series, User'S And Service Manual

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Capturing Data 3
Agilent 3000 Series Oscilloscopes User’s Guide 65
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
, Agilent Application Note
1587 ( http://cp.literature.agilent.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.
Figure 29 Sample Rate and Oscilloscope Bandwidth
f
S
f
N
f
S
/4
-3dB
Attenuation
Aliased frequency
components
Frequency
Limiting oscilloscope bandwidth (f
BW
) to 1/4 the sample rate (f
S
/4) reduces
frequency components above the Nyquist frequency (f
N
).
0dB