Sampling Theory; Aliasing; Oscilloscope Bandwidth And Sample Rate - Keysight Technologies InfiniiVision 2000 X Series User Manual

Sampling Theory

The Nyquist sampling theorem states that for a limited bandwidth (band-limited)
signal with maximum frequency f
must be greater than twice the maximum frequency f
signal be uniquely reconstructed without aliasing.

Aliasing

Aliasing occurs when signals are under-sampled (f
distortion caused by low frequencies falsely reconstructed from an insufficient
number of sample points.
Figure 33 Aliasing

Oscilloscope Bandwidth and Sample Rate

An oscilloscope's bandwidth is typically described as the lowest frequency at
which input signal sine waves are attenuated by 3 dB (-30% amplitude error).
Keysight InfiniiVision 2000 X-Series Oscilloscopes User's Guide
f = f /2 = Nyquist frequency (f
MAX S
, the equally spaced sampling frequency f
MAX
MAX
) = folding frequency
N
< 2f
S
Acquisition Control
, in order to have the
). Aliasing is the signal
MAX
12
S
179