LeCroy DDA 7 Zi series, Operator'S Manual

Page: 319 / 544

Operator's Manual
WP700Zi-OM-E-RevA
318
In normal trigger mode, multiple waveforms are acquired and processed. The histogram will typically have data
that is not well centered or is off screen. Touch the
FIND CENTER AND WIDTH button to see the pit width
distributions as they accumulate. After enough measurements have been taken, stop the triggering. After the
histogram has been centered, the screen will look as follows:
The optical data waveform is on the top and the histogram is on the
bottom. Notice the clustering of width distributions.
By enabling cursor tracking, the difference cursors are swept across
the histogram. As expected, the space between the 3T and 4T
distributions is the shortest, because of inter-symbol interference and
the many 3T widths. The spacing is 138 ns.
To measure the spread of widths for the distributions, set the measure mode to My Measure and configure the
parameters:
1. P2: average of F2
2. P3: high of F2
3. P4: low of F2
4. P5: range of F2
Because parameter measurements are performed only on those portions of the waveform between the parameter
cursors, activate tracking so that they can be swept across the histogram. Set the difference between the cursors
so that they encompass one clock period. In this case, the histogram is shown at 0.2
P
s per division. Set the
difference between the parameter cursors to:
This screen shows the histogram statistics taken on the 5T
distribution. The distribution has the largest spread of values:
102.5 ns. The mean is 1.1659
P
s, which is 3.6% higher than the
ideal of 1.1575
P
s.