Overview Of Sampling; Sampling Theory; Aliasing - Agilent Technologies 4000 X-Series User Manual

Overview of Sampling

To understand the oscilloscope's sampling and acquisition modes, it is
helpful to understand sampling theory, aliasing, oscilloscope bandwidth
and sample rate, oscilloscope rise time, oscilloscope bandwidth required,
and how memory depth affects sample rate.

Sampling Theory

The Nyquist sampling theorem states that for a limited bandwidth
(band- limited) signal with maximum frequency f
sampling frequency f
f

aliasing.

Aliasing
Aliasing occurs when signals are under- sampled (f
the signal distortion caused by low frequencies falsely reconstructed from
an insufficient number of sample points.
Figure 34
Agilent InfiniiVision 4000 X-Series Oscilloscopes User's Guide
, in order to have the signal be uniquely reconstructed without
MAX
f = f /2 = Nyquist frequency (f
MAX S
Aliasing
must be greater than twice the maximum frequency
S
) = folding frequency
N
Acquisition Control
, the equally spaced
MAX
< 2f ). Aliasing is
S MAX
12
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