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Dear Colleagues, As recently announced, I would like to start a thread on the reflector that will facilitate further ad hoc work on comments received against Annex 113A as needed in advance of next week’s P802.3bq Task Force meeting. As a starting point, interested participants are asked to please refer to materials from the September 2nd Rx CMNR ad hoc meeting, posted in the P802.3bq public area.
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Comment summary as of September 2nd - “P802.3bq D2.2 Comments – Annex 113A”.
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Comments against Annex113A from Larry Cohen (Thank you for your work, Larry!) “Annex 113A Comments for P802.3bq.”
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September 2nd
Meeting minutes Discussion from last week’s meeting are copied here as a starting point for ongoing discussion as needed.
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Comment #135:
(1)
Participants agreed with the proposed response to this Editorial comment.
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Comment #136:
(1)
The intent of the comment is allow test practitioners some flexibility in the hardware and techniques used to measure induced common-mode and differential-mode signals during the validation phase of the cable clamp test setup. Participants
agreed that providing this flexibility is helpful and that the proposed text is an excellent starting point and needs only relatively small changes (formatting/identification of “Note 1” and “Note 2”).
(2)
During discussion, it was noted changing the lower specification limit to 30MHz, while aligned with P802.3bz ENUCA ad hoc discussions related to Clause 126.5.4.3, has the potential to obviate a more general application of Annex 113A
to other cable clamp tests. Participants were reminded that the intent of defining a 1MHz to 2GHz range for equipment used in the cable clamp test setup is allow the “calling” specification to use such bandwidth as needed for a particular specification.
Participants agreed to review the text in “Annex 113A.1 Overview” and to develop appropriate text to include in the overview to clarify and/or emphasize that the equipment bandwidth defined in Annex 113A intentionally may exceed the range defined in any normative
text that references Annex 113A.
(a)
Assuming that the lower frequency range of Annex 113A will remain at 1MHz, the lower frequency ranges of proposed updates to the balun specifications will be updated to align with the 1MHz limit or lower range of the target baluns, whichever
is greater.
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Comments related to modifying the text to reflect the test frequency sweep range, which in general suggested increasing the lower frequency range from 1MHz up to 30MHz, should be addressed by clarifying that the “calling” normative
specification defines the limits to be used for a specific PHY rate.
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Comment #140:
(1)
The comment proposes modifying the measurement setup used in 113A.3 Cable Clamp Validation to allow better characterization of the signal injected at the clamp input. Inserting a directional coupler between the signal generator and
the clamp input, and replacing the “Signal Sensor” with a 50 ohm termination would allow better characterization of the injected signal power level, harmonic distortion, and envelope rise/fall time.
(2)
Participants asked to see a comparison between signal measurements made using the existing configuration and the proposed modification to better understand the advantages of the proposed change.
(3)
Details of the proposed modification to the test setup may be found on Page 3 of “Annex 113A Comments for P802.3bq.”
(Note – this document provides additional background information on several other comments discussed in these minutes.)
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Comment #189:
(1)
The comment proposes removing the suggested compensation for unloaded clamp losses. During discussion, participants noted that the intent of this were alerted to the fact that there are several instances where normative language has
been used in the Annex, and these should be reviewed and updated with text that is more appropriated for an informative portion of the specification.
(a)
As an example, the text for Note 1 currently reads as “NOTE 1 —Prior to making validation measurements or performing the test described in 113A.4, the cable clamp should be tested without the cable inserted to determine the variation of the signal generator
voltage with frequency at the output of the clamp. The signal generator output should be adjusted to the specified signal power (for example 6 dBm for 40GBASE-T) at 20 MHz on the signal sensor. When the frequency is varied from 1 MHz to 2000 MHz, the measured
power should not vary more than ±10 %. If the measured power varies more than ±10%, then a correction factor
must be applied at each measurement frequency.”
Participants were reminded that the intent of this calibration process is to parallel the “field calibration with no EUT in place” procedure defined in IEC 61000-4-3, 6.2 “Calibration of field” so that a constant
source power reference is established over the test frequency range before validating the setup and performing the test. Participants were asked to consider if an alternate remedy that removes the restrictive language would be an acceptable alternative. In this case the text “…then a correction factor
must be applied at each measurement frequency.” would be changed to “…then a correction factor
may be applied at each measurement frequency.”
Thank you in advance for your participation as we work to address these comments in a constructive and productive manner! Best regards, Pete Cibula |