Sample Rate - Rigol DHO900 Series User Manual

7.3

Sample Rate

Sampling is the process of converting an analog signal into digital data at a specified
time interval and then storing them sequentially in acquisition memory. The sample
rate is the reciprocal of the time interval.
In Horizontal menu, the "SaRate" item shows the current sample rate. The current
sample rate is also indicated in the acquisition label ("A" icon) at the top of the
screen, as shown in the figure below.
Sample Rate
The sample rate of the analog channel is related to the current channel mode. This
series oscilloscope provides up to 1.25 GSa/s real-time sample rate in single channel
mode, 625 MSa/s real-time sample rate in half channels mode, and 312.5 Msa/s real-
time sample rate in all channels mode.
• Single channel mode: If any one of the channels is enabled, it is called single
channel mode.
• Half channels mode: If two of the channels are enabled, it is called half channels
mode.
• All channels mode: If any three channels or all four channels are enabled, it is
called all channels mode.
A sample rate that is too low might have the following effects on the waveform:
• Waveform Distortion: When the sample rate is too low, some waveform details
are lost, and the sample waveform displayed is rather different from the actual
waveform of the signal.
• Waveform Aliasing: Aliasing occurs when the sample rate is twice lower than
the actual signal frequency (Nyquist Frequency). The frequency of the waveform
reconstructed from the sample data is smaller than the actual signal frequency.
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Acquisition System
Sample Interval
DHO900 User Guide
55