BERTScope Newsletter  June 2008
 

Welcome to the BERTScope Newsletter – the latest hints, tricks, and tutorials on signal integrity measurements from SyntheSys Research, Inc. We hope that you will enjoy this and future editions.


How-to Articles

Optical Tx Jitter Measurement Basics

Application Note: "Optical Transmitter Jitter Measurement Basics."   Understand the fundamentals of transmitter test methodologies, applying to many electrical standards also.

 
Combating Closed Eyes

Application Note: "Combating Closed Eyes: Pre-Emphasis and Equalization Basics." Comprehensive introduction to overcoming the dispersive effects of circuit boards and backplanes at high data rates.

 

Great Resources

Impact of Clock Recovery

Impact of Clock Recovery on Measurements by Steve Sekel, Webinar, Sponsored by EDN

 
Jitter generation correlation study

Product Note: DCRj and Omniber OTN 10 Gb/s Telecom Jitter Generation Correlation Study
Critical SONET, SDH, G.709, and OTU-2e/f measurements examined.

 

What's New at SyntheSys?

4-tap pre-emphasis

4 Tap Just Announced: New BERTScope DPP flexible pre-emphasis instrument for 10GBASE-KR is now optionally available with 4 tap control.   ...Read More

PCIe test results

Prepare for the September 2008 deadline for mandatory PCI Express® (PCIe) PLL testing with the BERTScope PLL Analyzer (PLA) Compliance Test Solution for PCIe components and add-in cards.   ...Read More

BERTScope standalone operation

Many BERTScope products are now available standalone for control with a computer, such as:

BERTScope DPP pre-emphasis processor

BERTScope DCRj optical receiver and telecom jitter analyzer

BERTScope LTS 850 nm optical stress source

Come and See us at...

PCIe Developers’ Conference
Santa Clara, June 11-12

Intel Developers' Forum
San Francisco, August 19-21

ECOC
Brussels, September 22-24


Question: Why does the deterministic jitter (DJ) seem to disappear when I measure longer patterns using a bathtub jitter method?

Answer: Bathtub jitter measurements (also known as BERTScan, and Jitter Peak on a BERTScope) are the most accurate way of measuring the total jitter (TJ) at deep BER levels, according to MJSQ[1]. Longer patterns such as PRBS-23 and PRBS-31 have jitter-inducing bit sequences that appear very infrequently, and so can look like random jitter (RJ) fooling the dual-Dirac math. If possible, an alternative is to measure a clock pattern (such as 1100) to get an accurate RJ/DJ separation. Then, using the TJ measured on the long pattern, subtract the RJ result from the clock pattern to arrive at the long pattern dual-Dirac DJ.

More information on Bathtub jitter measurements can be found here.

[1] MJSQ: Methodologies for Jitter and Signal Quality Specification is a document written as part of the INCITS project T11.2.


Science Puzzler

Q: If you wear polarized sunglasses while driving, you have probably noticed the large spots, usually arranged in patterns, on the rear windows of other cars. What are those spots, and why do polarized sunglasses reveal them?

Click for answer
 

Quote of Note

"It is amazing what you can accomplish if you do not care who gets the credit."

     — Harry S Truman
     (1884 - 1972), 33rd President
     of the United States

 

Guess What?


(Click for answer)


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