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input signals to an digital- to- analog converter (DAC), while the stair- step
sine wave is the output of the DAC. At this point, you may be wondering
where these digital signals are coming from. Are they real or just
simulated? They are real signals generated by an internal pattern
generator inside the scope. They are then internally routed directly to
eight digital/logic acquisition channels of the scope (D7- D0); bypassing the
parallel logic probe. In a real measurement application such as this, you
would use the logic probe that is supplied with the scope to probe signals
such as these.
The scope is currently triggering on the output of the DAC (channel- 1)
using the scope's default Edge triggering mode. We can also set up the
scope to trigger on Boolean pattern conditions based on the input of the
DAC (D7- D0), which might be necessary if the output signal were more
complex than a repetitive sine wave. Let's now set up the scope to trigger
on an input pattern condition = 1110 0110 (binary D7 – D0), which is
equivalent to E6 (HEX). Note that this input logic pattern condition will be
coincident with the highest output level of the DAC (positive peak of the
stair- step sine wave).
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2000 X-Series Oscilloscopes Advanced Training Guide
Advanced Triggering, Search & Navigation, and Segmented Acquisition Labs
Press the [Trigger] front panel key; then select Pattern using the Entry
knob.
Press the Channel softkey; then select D7 using the Entry knob.
Press the Pattern softkey; then select 1 as the pattern condition for D7.
Press the Channel softkey two times to select D6.
Press the Pattern softkey; then select 1 as the pattern condition for D6.
Repeat the above process until:
Pattern = 1 XX 2 D
1110 0110 D
7
0
3
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