User Manual

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Trigger Level Knob: Sets the voltage or current level that the oscilloscope will
trigger at. This trigger level is displayed in the upper right portion of the
display. Press the knob to set the trigger level to 50% of waveform's
amplitude.
5.1 Overview of triggering
The trigger determines when the oscilloscope starts to acquire data and display a waveform.
When a trigger is set up properly, the oscilloscope converts unstable displays or blank screens
into meaningful waveforms
Note: the 2540C Series oscilloscopes allow the use of either voltage or current units for waveform
measurements. The remainder of this chapter will refer to just voltages, but it applies to current
levels, too.
5.2 Auto Setup
The oscilloscope automatically identifies the waveform type, trigger level, and scales to produce
a usable display of the input signal.
Press the Auto Setup button to perform the function and the following softkeys will be available.
Softkey
Description
Multiple cycles
Shows multiple cycles. This is the default behavior.
One cycle
Shows one cycle of the waveform.
Rising edge
Puts a rising edge at the center of the screen by changing the
trigger slope to positive.
Falling edge
Puts a falling edge at the center of the screen by changing the
trigger slope to negative.
Restore previous settings
Go back to your previous settings. This acts like an undo button.
Noisy sine wave
Changes to averaging mode with a sample size of 16 to reduce
noise.
If the waveform is out of the Auto Setup's range, a dialog window will is displayed explaining that
Auto Setup did not work.
5.3 Setting the Trigger
Digital oscilloscopes capture the waveform continuously, but will not display the captured
waveform unless the oscilloscope is triggered. A stable display needs a stable trigger. The
triggering circuitry generates a trigger event when the logical trigger conditions are satisfied by
the waveform.