BK Precision 2194, User Manual

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Sample Control
5.1 Run Control
Press the Run/Stop or the Single key to stop the sampling system of the scope.
• Running : When the Run/Stop key is green, the oscilloscope is continuously acquiring data.
– To stop acquiring data, press the Run/Stop key.
– When the Run/Stop button is red, data acquisition is stopped.
– Red "Stop" text is displayed next to the trademark logo in the status line at the top of the display.
– To start acquiring data, press Run/Stop.
• Single : Clears the display, the trigger mode is temporarily set to Normal (to keep the oscilloscope from auto- triggering
immediately), the trigger circuitry is armed, the Single key is illuminated, and the oscilloscope waits until a user defined
trigger condition occurs before it displays a waveform.
– When the oscilloscope triggers, the single acquisition is displayed and the oscilloscope is stopped (the Run/Stop
button is illuminated in red).
– Press the Single key again to clear the current waveform and acquire a new one.
Note:
The Single run control lets you view a single shot events without subsequent waveform data overwriting the display. Use
Single when you want maximum memory depth for pan and zoom.
5.2 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
= 𝑁 𝑦𝑞𝑢𝑖𝑠𝑡 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦(𝑓
𝑁
) = 𝑓𝑜𝑙𝑑𝑖𝑛𝑔 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦
5.3 Sample Rate
The maximum sample rate of the oscilloscope is 1G Sa/s. The actual sample rate of the oscilloscope is determined by
the horizontal scale. See section Horizontal Scale
The actual sample rate is displayed in the information area at the upper- right corner of the screen.
Figure 5.1 Actual Sample Rate