Teledyne LeCroy SDA III-CompleteLinQ - Manual (Page 39)

Operator's Manual
Pattern Analysis
A progress bar and helper information is displayed under the Pattern Analysis button, and an LED above
to inform the user the status of the pattern analysis.
1. First the data pattern is found.
2. Then, a DDj analysis is performed on the TIE trend. The average TIE is calculated for each DDj class.
The DDj classes can be defined either by where the edge occurs in a repetitive pattern or by the N-bit
sequence occurring prior to the edge.
3. From this analysis, a list of DDj values and populations is created for each classification made from
step 1.
4. From this analysis, the following are calculated:
l
DDj histogram
l
DDj plot
l
DDj parameter
l
DCD (Duty Cycle Distortion ) parameter
l
ISI parameters
5. The DDj is removed from each edge in the TIE Trend (according to their classification from step 1) to
create an RjBUj TIE Trend (RjBUjTrend), a TIE sequence (in which the DDj is removed, but still con-
tains all the (Rj) Random jitter, and the (BUj) Bounded-Uncorrelated jitter). The most common case
of BUj is periodic jitter, where the period is unrelated to the data rate.
Jitter Track
1. In this step, the RjBUjTrend is converted to a track (RjBUjTrack) by inserting interpolated samples
into the RjBUj Trend for each UI where there was no edge, thereby yielding a uniformly sampled TIE
waveform with a sample for every UI and a time axis.
2. This function provides the capability to show/hide the RjBUjTrack, the TIETrack, and the PLLTrack.
The PLLTrack shows the jitter tracked out by the PLL compared to an ideal clock of frequency (found
by the Find Bit Rate function).
Jitter Spectrum
1. The spectral analysis step takes the FFT of the RjBUjTrack (DDj removed). Notice how the Jitter Spec-
trum is showing magnitude. Therefore, to get peak-to-peak jitter you must multiply by 2.
2. The background of the spectrum is estimated and integrated to get a spectrally derived Random
jitter, Rj(sp). If the jitter model selected in the Jitter Params dialog is Dual-Dirac Spectral, then this is
the Rj used in the jitter breakdown.
3. The peaks in the spectrum are identified and used for further periodic jitter analysis.
4. A version of the spectrum is created which only keeps the peaks above the threshold.
5. The inverse FFT (PjInvFFT) of the peaks only spectrum is created. The peak-to-peak Pj is measured
from this waveform.
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