Agilent Technologies InfiniiVision 3000 X- Series Advanced Training Manual page 41

3
Advanced Triggering, Search & Navigation, and Segmented Acquisition Labs
You should see on your scope's display what may appear to be an
un- triggered display of a series of digital pulses similar to Figure 22. The
scope is actually triggering on random rising edge crossings of this
complex digital data stream, which is actually a "burst" of pulses.
Unfortunately we can't "see" the burst activity because we haven't yet set
up the scope to establish a unique trigger point on this complex signal. So
let's now "stop" repetitive acquisitions so that we can see a single- shot
acquisition of the bursts, and then make some measurements. We will then
use these measurements to enter a specific trigger holdoff time in order to
synchronize triggering on the 1st pulse of each burst.
Press the [Run/Stop] front panel key to stop repetitive acquisitions.
9
Figure 23 Single-shot acquisition reveals digital burst activity.
With repetitive acquisitions stopped, you should now be able to see digital
burst activity as shown in Figure 23. In other words, there are a series of
negative pulses followed by a short idle- time (high level), and then it
repeats. If you press [Single] several times, you should observe that the
trigger event (rising edge closest to center- screen) for each acquisition is
almost always a different pulse within the burst.
Estimate or use the scope's timing cursors (X1 & X2) to measure the
width of one of the burst of pulses, and also measure the time from the
beginning of one burst of pulses to the beginning of the next burst of
pulses. You should find that the width of each burst is approximately
40 µs, and the time between bursts is approximately 50 µs.
3000 X-Series Oscilloscopes Advanced Training Guide 41