User Manual

44
4 Sample System Configuration
This chapter shows how to use the run control and set the sampling system of the oscilloscope.
4.1 Run Control
Press the Run/Stop or Single button on the front panel to run or stop the sampling system of the scope.
 When the Run/Stop button is green, the oscilloscope is running (acquiring and storing data
when the trigger conditions are met). To stop acquiring data, press the Run/Stop button.
When stopped, the last acquired waveform is displayed.
 When the Run/Stop button is red, data acquisition is stopped. A red "Stop" is displayed next
to the B&K logo in the status line at the top of the display. To start acquiring data, press
Run/Stop.
 To capture and display a single acquisition (whether the oscilloscope is running or stopped),
press Single. The Single run control lets you capture single-shot events without subsequent
waveform data overwriting the display. Use Single when you want maximum memory depth
for pan and zoom.
When Single is pressed, the display is cleared and the trigger mode is temporarily set to Normal
to keep the oscilloscope from auto-triggering immediately. The trigger circuitry is armed and the
Single key is illuminated. The oscilloscope will wait until a user-defined trigger condition occurs.
After triggering, the captured waveform is displayed and the oscilloscope is stopped (the
Run/Stop button will be red).
Press Single again to acquire another waveform. You can save the stored waveform to a flash
disk if you wish.
4.2 Overview of Sampling
To understand the sampling and acquisition modes of the oscilloscope, it is helpful to understand
sampling theory, sample rate, and oscilloscope bandwidth.
Sampling Theory
The Nyquist sampling theorem states that for a band-limited signal with a maximum frequency
compliment f
MAX
, the equally-spaced sampling frequency f
S
must be greater than twice the
maximum frequency f
MAX
for the signal to be accurately reconstructed without aliasing.
f
MAX
= f
S
/2 = Nyquist frequency (f
N
) = folding frequency
The other requirement of the theorem is that the samples be taken at equal intervals.
Sampling Rate
The maximum sampling rate of the oscilloscope is 2 GSa/s. The actual sampling rate of the
oscilloscope is determined by the horizontal scale. Turn the Horizontal Scale knob to adjust the
sampling rate.