Tektronix CSA7404B, User Manual

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Measuring Waveforms
3- 142
CSA7000B Series & TDS7000B Series Instruments User Manual
Take Measurements on a Frame. In FastFrame, measurements are taken only on
the displayed frame.
Read the following topics; they provide the details that can help you set up
automatic measurements so that they best support your data-analysis tasks.
Measurement Selection.
The instrument takes automatic measurements of the
following categories: Amplitude, Timing, More, Histogram, and Comm
(optional on TDS7000B Series). Check
Appendix B: Automatic Measurements
Supported for a listing of the measurements that you can choose.
Number of Measurements.
The instrument can take and update up to eight
measurements at one time. You can apply measurements to any combination of
sources (described below). You can take all eight measurements on Ch1, for
example or you can take measurements on Ch1 -- Ch4, Math1 -- Math4, Ref1 --
Ref4, or a histogram.
Measurement Sources.
All channel, reference, and math waveforms can serve as
sources for automatic measurements.
Some measurements, such as delay and phase, require two sources. For example,
delay would be used to measure an input from one measurement source (for
example, C1) with respect to an output in another source (C2).
High/Low Method.
The levels that the automatic measurement system derives as
the High (Top) or Low (Bottom) for a waveform influence the fidelity of
amplitude and aberration measurements. You can select among the modes the
instrument provides for determining these levels. You can set the modes
differently for each measurement:
H
Histogram
.
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 so on.), Histogram is the best
setting for examining pulses. See Figure 3--36.
Using Automatic
Measurements