User Manual

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Here is a schematic diagram of the acquisition memory. The position of the trigger event in time
is defined to be the zero-time location. Waveform samples before the trigger event are in the
pre-trigger buffer and samples after the trigger event are in the post-trigger buffer. By default,
the trigger event is shown at the center of the screen, but turning the horizontal position knob
lets you put other portions of the buffer in the center of the screen.
Choosing the right trigger mode and setting it up correctly can take some practice and it is best
done if you know something about the signal you are trying to capture. The oscilloscope provides
a variety of triggering types and logical conditions for generating a trigger event, such as Edge,
Slope, Pulse, Video, Window, Interval, Dropout, Runt, Pattern and Serial triggering. These
triggering types will be discussed in the following sections.
5.4 Trigger Source
The trigger source is the signal that will be compared to the logical conditions you set to generate
a trigger event. The most common trigger source is the signal on one of the analog input channels,
but the EXT BNC connector on the front panel can be used to trigger on an external signal. If you
are looking at waveforms that are derived from the AC line power, you'll probably want to use
the AC line as the trigger source. For example, to measure the 120 Hz ripple in a voltage regulator
circuit, you'd want to trigger on the 60 Hz AC line for a stable signal.
Press the Setup button in the Trigger section on the front panel to enter the TRIGGER menu.
Press the Source softkey and then turn the Universal Knob to select the desired trigger source.
The current trigger source is displayed at the upper right corner of the screen.
The edge trigger type allows triggering from the analog channels, an external signal on the EXT
input terminal, or the AC line. The remaining triggering types use only the analog channels as
their source.
If you select the Serial trigger type, the Source softkey changes to the Protocol softkey.
For the analog and external triggers, the trigger level can be set from about -4 to 4 screen
divisions.
5.5 Trigger Mode
The three trigger modes are Auto, Normal and Single.
Figure 43 - Acquisition Memory Schematic