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SDA Operator’s Manual

3. Note the change in the DDj measured value.

4. Touch the ISI Edge-Edge tab.

A. Touch the Detect Pattern button to find the pattern and length. Normally this is

done automatically when the signal is set up in the SDA main menu. The Patt.

Length control in the SDA main dialog indicates the repetition length of the

pattern.

B. The pattern is indicated in Hexadecimal in the Pattern window. This window

allows you to view and edit the pattern. The Find Pattern Length button in the

SDA main dialog searches the pattern for specific hex values.

C. Check the Error Relative to First edge checkbox to display the plot of edge

position errors relative to the first transition in the data pattern.

D. Check the Show Graphic Bit Pattern checkbox to display a trace showing the

bit pattern in the grid with the synchronous n-cycle plot. The transitions of the

pattern line up with the measurement points in the plot.

DDj (ISI plot) – ASDA-J Option Only

A repeating data pattern is not always present in cases where there is no ability to program the

PHY under test. The ASDA-J option includes an alternate method of measuring data dependent

jitter that does not rely on a repeating pattern. This plot shows an eye pattern consisting of the

averaged waveform trace from each pattern in the data stream of a specified length, which can

be adjusted from 3 to 10 bits. The value of DDj is the width of the zero crossing at the right side of

the ISI eye at the threshold level set by the DDj threshold value.

SDA-OM-E Rev H 339

LeCroy SDA User Manual

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