Teledyne LeCroy SDA II - Manual (Page 27)

Operator's Manual
Eye Patterns
SDAIImeasures eye patterns without using a trigger. This is done using the software clock recovery (dis-
cussed in
Set Up Clock Recovery ) to divide the data record into segments along the time values of the
clock. For the purpose of dividing the time line into segments, the time resolution is essentially infinite.
The samples occur at fixed intervals of 25 or 50 ps/pt (for 40 or 20 GS/s sampling rate). The samples are
positioned relative to the recovered clock edge times, and the segments delimited by the clock (the unit
intervals or bits) are overlayed by aligning the clock delimited boundaries.. A monochrome or color per-
sistence display is used to show the distribution of the eye pattern data. Since the unit inteval are deter-
mined from the recovered clock and not from the oscilloscope's trigger position, this method does not
include jitter from any trigger circuit.
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