Triggering
TDS5000 Series User Manual
3-53
Horizontal position is an adjustable feature that defines where the trigger occurs
on the waveform record. It lets you choose how much the oscilloscope acquires
before and after the trigger event. The part of the record that occurs before the
trigger is the pretrigger portion. The part that occurs after the trigger is the
posttrigger portion.
Pretrigger data can be valuable when troubleshooting. For example, if you are
trying to find the cause of an unwanted glitch in your test circuit, you can trigger
on the glitch and make the pretrigger period large enough to capture data before
the glitch. By analyzing what happens before the glitch, you may uncover
information that helps you find the source of the glitch.
The slope control determines whether the oscilloscope finds the trigger point on
the rising or the falling edge of a signal (see Figure 3--22). Set the trigger slope
by pushing the SLOPE button on the front panel to toggle between the positive-
going and negative-going edge.
The level control determines where on that edge the trigger point occurs. (see
Figure 3--22.) You can set the trigger level with the LEVEL knob on the front
panel. Push the LEVEL knob to automatically set the trigger level to the 50%
amplitude point of the signal.
Positive-going edge Negative-going edge
Trigger slope can be positive or negative.
Trigger level
can be adjusted
vertically.
Figure 3- 22: Slope and level controls help define the trigger
You can trigger with the A (Main) trigger system alone or you can combine the
A (Main) trigger with the B (Delayed) trigger to trigger on sequential events.
When using sequential triggering, the A trigger event arms the trigger system,
and the B trigger event triggers the oscilloscope when the B trigger conditions
are met. A and B triggers can (and typically do) have separate sources. The B
trigger condition can be based on a time delay or a specified number of counted
events. See Sequential Triggering on page 3 --91 to learn how to use the delayed
trigger system.
Horizontal Position
Slope and Level
Delayed Trigger System
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