User`s guide

Known Pattern with Marker
Applications of Known Pattern with Marker tool
• Show Jitter and its components on a pattern relative to its ideal position
• Analyze a data pattern and decompose or separate the various jitter components so the designer can
better understand and improve system performance
• Measure the deterministic components: Duty-Cycle Distortion and Intersymbol Interference
(DCD+ISI), Periodic Jitter (PJ), Bounded Uncorrelated Jitter (BUJ), Deterministic Jitter (DJ)
• Measure the Gaussian—or Random Jitter (RJ) component
• View DCD+ISI relative to pattern transition density
• Compliance testing Fibre Channel and Gigabit Ethernet devices
• Advanced (not covered in this guide): view jitter data and model the signal as seen by the receiver,
filtering RJ and PJ or altering acquisition configuration
This tool provides the fastest, most complete measurements for compliance testing. Histograms of every
edge in the pattern are made in order to determine DCD+ISI. Spectral content is measured to determine
PJ contribution and in the presence of significant PJ, TailFit can be enabled to determine a more accurate
RJ. TJ is based on the convolution of DJ and RJ values.
To use this tool, you will need:
(1) A known repeating pattern (k28.5, PRBS2^7-1, CJTPAT, custom user pattern, etc)
(2) A pattern marker, which is a separate signal that has one edge per pattern repeat. This signal
does not need to be at a particular part of the pattern (like start of pattern) but it must always
maintain the same relative position to a particular point in the pattern (it is synced or not moving
with respect to the pattern. Many Data Pattern generators can create this signal as a "trigger").
Measurments KPwM Can Make
DCD + DDJ PJ DJ RJ TJ Views (Plots)
X X X X X DCD+ISI Histogram
DCD+ISI vs Span
1 Sigma
FFT Bathtub
UI Distribution
Summary
Signal Requirements (1)Repeating, known data pattern (2)Pattern Marker signal
Benefits • Compliance Testing
• Measure Data Jitter relative to ideal data pattern (not to a reference signal)
• Shows the most components of jitter
• Spectral content of jitter
• DCD+ISI (DDJ)
• RJ (accumulated effects)
• Speed
Disadvantages • Need to provide a marker
• Need a repeating pattern
Section 4 - GigaView © WAVECREST Corporation 2005
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