Oscilloscope Reference Automatic measurements
can take measurements on a combination of channel waveforms, math waveforms, reference waveforms,
and/or histograms.
High/Low method
The levels th
at the automatic measurement system derives as the High (top) or Low (bottom) for a
waveform influence the fidelity of amplitude and aberration measurements. Select among the modes the
instrument provides for determining these levels:
Histogram mode sets the values statistically. It selects the most common value either above or below
the midpoint (depending on whether it is defining the High or Low reference level). Since this
statistical approach ignores short term aberrations (overshoot, ringing, and s o on), Histogram is the
best setting for examining pulses. See the next figure.
Min-Max mode uses the highest and lowest values of the waveform record. This setting is best for
examining wav eforms that have no large, flat portions at a common value, such as sine waves and
triangle waves (almost any waveform except for pulses). See the next figure.
Refe
rence levels method
A second set of levels affect the fidelity of time-related measurements. For example, the measurement
sys
tem calculates rise time from the waveform edge that transitions from the Low to the High reference
levels.
Th
e instrument provides the following calculation methods (see the next figure):
Relative Reference is calculated as a percentage of the H igh/Low range.
Absolute Reference is set by absolute values in user units.
DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series 725
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