XScopes
User’s Manual
DS-XScopes-3.5
– December, 2014
Page | 17
2.3.3
Trigger Hold
The trigger hold specifies a time to wait before detecting the next trigger. It is useful when the signal can have multiple
trigger events occurring close to each other, but you only want to trigger on the first one.
2.3.4
Post Trigger
The oscilloscope is continuously acquiring samples in a circular buffer. Once the trigger event occurs, the oscilloscope
will acquire more samples, specified by the Post Trigger value. The ability to show samples before or after the trigger is
one of the most powerful features of a digital sampling oscilloscope. The post trigger is only available on the fast sampling
rates.
Depending on the post trigger settings, different parts of a signal can be displayed. Consider the signal on figure 28:
Figure 28: Sample signal
Even though the buffer sample is relatively small, any section of the shown figure can be analyzed by varying the post
trigger value. Examples:
-
Post trigger = 0 (don’t acquire more signals after the trigger).
Only the signals that occurred before the trigger event are shown.
Figure 29: Post trigger value equal zero
-
Post trigger = 50% of the sample buffer (default setting).
Half of the buffer contains samples before the trigger,
and half contains the samples after the trigger.
Figure 30: Post trigger = 50% of sample buffer
-
Post trigger = 100% of the sample buffer
Only signals immediately after the trigger event are shown.
Figure 31: Post trigger = 100% of buffer
The actual post trigger value can vary between 0 and 32768 samples, so you can explore the signal after a very long
time after the trigger event has occurred, but with a high post trigger value, the refresh rate of the scope will be reduced.
2.3.5
Trigger Source
Any analog or digital channel can be the trigger source. If selecting a digital channel as trigger source, the slope and
window modes are not applicable; the device will use edge triggering. The external trigger input is an additional digital
trigger source which tolerates voltages up to 5.5V.
Summary of Contents for XScopes
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