Advanced Triggering, Search & Navigation, and Segmented Acquisition Labs
3
4000 X-Series Oscilloscopes Advanced Training Guide
49
You should now see on your scope’s display a digital burst waveform consisting of
six pulses of various widths, followed by an infrequent glitch similar to
.
Using the scope’s default Edge triggering mode, the scope usually triggers on the
1st pulse of this burst. But if you increase the scope’s waveform intensity to 100%,
you will see that the scope sometimes triggers on later pulses within this burst.
We could further stabilize triggering on the 1st pulse in this burst if we used the
scope’s trigger holdoff capability. But what if we wanted to trigger on a specific
pulse (other than the 1st pulse)? We could accomplish this by using the “Nth Edge
Burst” triggering mode, assuming that the input signal is a repetitive burst. We will
show how to use the “Nth Edge Burst” triggering mode in the next lab (Lab #9).
Another option would be to use the scope’s “Pulse Width” triggering mode, which
can be used on a continuous data stream of digital pulses; the data stream does
not need to come in bursts. But the pulses must have a unique pulse width for this
triggering mode to be effective. Note that the 5th pulse within this burst has a
positive pulse width of approximately 300 ns. This is a unique pulse width within
this burst of pulses. Let’s now set up the scope to trigger specifically on this pulse.
9
Press the
[Trigger]
front panel key; then tap the
Pulse Wid th
trigger type from
the
Trigger Type
menu.
10
Tap the “
< > ><
” softkey until the “
><
” time qualifier has a check below it.
11
Tap the “
< 30 ns
” softkey; then set the time to
< 350 ns
using the keypad.
12
Tap the “
> 20 ns
” softkey; then set the time to
> 250 ns
using the keypad.
13
Set the scope’s timebase to
500.0 ns/div
.