Keysight 4000 X-Series, Руководство по продвинутой подготовке

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30 4000 X-Series Oscilloscopes Advanced Training Guide
2
Oscilloscope Familiarization Labs
At this point, you should see a sine wave similar to Figure 13 . But if you look
closely you should also see some glitches (narrow pulses) near the peaks of this
sine wave. And the amplitude of these glitches may appear to vary (bouncing up
and down). The amplitude of these glitches is actually very stable. The problem is
that the scope has reduced its sample rate (note the sample rate shown under the
Keysight logo on the scope’s display) and the scope is now intermittently
capturing the narrow glitches. The scope is under-sampling the narrow glitches.
Sometimes the scope captures a single point on the peak of a glitch. Sometimes it
captures a point on a transition of the glitch. And sometimes it captures nothing at
all on the glitch (the glitch width is narrower than the sample interval). This scope
has a special acquisition mode called “Peak Detect” that will resolve this problem.
Let’s turn it on.
8
Press the
[Acquire]
front panel key (below the Cursors knob).
9
Press the Acq Mode softkey and select Peak Detect .
Figure 13 The scope’s automatically-reduced sample rate under-samples the repetitive
glitch.