LeCroy DDA 7 Zi series, Руководство оператора

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Operator's Manual
WP700Zi-OM-E-RevA
380
The diagram on the previous page shows a data stream in relation to its clock signal. It illustrates how data pulses
contain, within themselves, multiples of their clock-signal pulse widths. Analyzing the positive pulses in the data
stream, we observe a great variance between each sample in, for instance, the range
7
to 3
7
. In fact, it is the
small variations (the jitter) that are important. And they could be normalized if clock frequency, and clock
frequency over pulse width, were known. This normalization, provided by JitterTrack, reduces pulse variations
and increases timing resolution so that errors (
H
) can be clearly observed. It does this by reducing the jitter range,
dividing each measurement equal to n
u 7
by n.
Modes CLOCK DATA
Jitter Range 3
7
+
H H
<< 3
7
Resolution coarse fine
Table 5-1.Comparing a Random Data Stream Analyzed Using Clock and Data Modes.
Setting Up Jitter Measurements
Jitter Math Setup
1. Touch Math in the menu bar, then Math Setup... in the drop-down menu.
2. In the "Math" dialog, touch an unused Fx button to simply make a selection from the Select Math Operator
menu. Or, touch an Fx tab for more setup options.
Note: By default, unused Fx positions are designated as zooms of C1. However, the traces are disabled, as
indicated by an unchecked On box alongside the Fx button .
3. Touch the Jitter Functions button in the Select Math
Operator menu for a list of
persistence functions.
4. Touch a persistence function. The Select Math Operator menu closes, and the trace is automatically
enabled.