SIGLENT SDS1104X-E - Overview; Sampling Theory; Sample Rate

SDS1000X-E&SDS1000X-U User Manual
42
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Overview
To understand the oscilloscope's sampling and acquisition modes, it is helpful to
understand sampling theory, sample rate and oscilloscope bandwidth and sample
rate.
Sampling Theory
The Nyquist sampling theorem states that for a limited bandwidth (band- limited)
signal with maximum frequency f
MAX
, the equally spaced sampling frequency f
S
must be greater than twice the maximum frequency f
MAX
, in order to have the signal
be uniquely reconstructed without aliasing.
f
MAX
= f
S/2
= Nyquist frequency (f
N
) = folding frequency
Sample Rate
The maximum sample rate of the oscilloscope is 2GSa/s. The actual sample rate of
the oscilloscope is determined by the horizontal scale. Turn the Horizontal Scale
Knob to adjust the sample rate.
The actual sample rate is displayed in the information area at the upper- right
corner of the screen.
The influence on the waveform when the sample rate is too low:
1. Waveform Distortion: when the sample rate is too low, some waveform details
are lost and the waveform displayed is rather different from the actual signal.