I think it is reasonable to specify this. However I think the intent is that no SJ is deliberately injected. (It is deliberately injected for the Jitter Tolerance test).
If SJ isn’t being adjusted then adjusting BUJ and RJ will have a unique solution to achieve the J4U03 and RJrms.
The clause you point to in 802.3ck was for C2M where jitter tolerance and interference tolerance equivalents were combined into one test, and specifying how much Sj (and it’s
frequency) is included in the test and is very important. The equivalent copper cable clause in 802.3ck (162.9.5.3) does not specify more than 802.3dj does.
Some clarification would probably help however.
From: Hadrien Louchet <000048266f3548a2-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Friday, July 11, 2025 9:36 AM
To: STDS-802-3-B400G-ELEC@xxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] [802.3_B400G_ELEC] Jitter profile for input test
Dear colleagues, I missed the deadline to submit a comment against Draft 2. 0, but this allows me to get your opinion on a specific aspect of the receiver input
test procedure. In several places—such as clause 179. 9. 5. 3. 3 (Test channel calibration,
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Dear colleagues,
I missed the deadline to submit a comment against Draft 2.0, but this allows me to get your opinion on a specific aspect of the receiver input test procedure.
In several places—such as clause 179.9.5.3.3 (Test channel calibration, CR) and annexes 176C (C2C) and 176D (C2M)—there is a recommendation to adjust the pattern generator jitter to approach practical limits
(23mUI Jrms, 120muI J4u03) before injecting broadband noise. Please see the screenshot below for reference.
However, unlike the CK standard (see 120G.3.3.5.1 Host stressed input test setup), these clauses do not specify the jitter mix.
My concern is that this could lead to receivers being tested with overly simplistic jitter profiles—e.g., using only sinusoidal jitter (SJ)—which may not reflect realistic stress conditions. For example, it
is possible to approach the 23 mUI Jrms target using only 50 mUI SJ.
Do you think we should clarify or tighten the guidance to ensure more representative jitter conditions?
Looking forward to your thoughts.
Best regards,
Hadrien
Best regards,
Dr. Hadrien Louchet,
Vertical Lead, Datacenter Networking
Keysight Technologies
Herrenberger Str. 130, D 71034 Boeblingen Germany
+49 7031 464 ext. 4089 T | +49 173 631 621 3 M |
email: hadrien.louchet@xxxxxxxxxxxx
Keysight Technologies Deutschland GmbH, Herrenberger Straße 130, 71034 Böblingen
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Geschäftsführer: Dr. Joachim Peerlings (Vorsitzender), Thomas Götzl
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