Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

[10GMMF] More on Tx jitter options for TP3

A few more thoughts on the Tx jitter generator for TP3 -
I suggested that a filtered PRBS generator may make some sense for the higher jitter frequencies. By filtered, I mean that the PRBS output would be filtered to spread what would otherwise be a bimodal probability function into something more uniform or normal. This signal could be applied to a phase modulation input, much the same as SJ is applied now.
Advantages of this approach are that it generates a wider spectrum that should be more realistic and testing would be done with a single test (no sweeping or multiple tests).
As I mentioned on the call, it could be done with something like PRBS7 running at ~1Gbd. The fundamental frequency in this case would be ~8 MHz with harmonics spaced at ~8 MHz up to the bandwidth of the filter. A figure is attached that shows this with a single-pole filter corner frequency at 60 MHz. Note the shape of the pdf and that it is clearly bounded.
On the other hand, if SJ does not cause EDC to do something that it would not do in application (which I don't think would happen), then it is probably preferred because it is familiar and has a lot of history.
----- Original Message -----
Sent: Tuesday, October 26, 2004 7:03 AM
Subject: [10GMMF] TP3 meeting Agenda + dial in Oct 26

Dear all,
Please find attached the slides for jitter tolerance. I will include
the sinusoidal interferer next week.
Regarding the laser maximum/minimum rise and fall times, they may
be included in the TP2 specification (see comments from Tom Lindsay).
For TP3 stressed sensitivity test, we have to generate the worst case
pulse response, based on the TP2 spec, the channel models (108 fibers,
fiber length to be decided), and including worst case connectors impact.
There is a significant amount of work to solve these issues and we need
to agree on a time line.
Best regards, Petre

Petre Popescu
Quake Technologies
613.220.8982 (cell)

Filtered PRBS7 jitter example.png