Re: [802.3_SPMD] Mode conversion loss requirement
Dear George
Sorry for my late reply, maybe you got one already but I have not seen anything on the reflector. Unfortunately I have lost my passwords for IEEE. If you could send them to me I could check the draft.
Mode conversion loss is described in two parameters depending on the direction of the mode conversion. TCL is the reflected mode conversion, similar to RL, TCTL the mode conversion to the far end. Then EL TCTL is the normalisation to the near end by deducting the IL.
From this we see already that the two parameters have to be different. Interestingly they are already different for connectors where the effect of IL is neglectable, but this has mainly historical reasons.
As we talk about single pair, TCL is directly coupled with the requirement for coupling attenuation, as the difference is screening attenuation. This is 0dB for unscreened cabling and 20-30dB for screened cabling. For 100BASE-T1L we have defined that indirectly, I don't know if there is something similar in the SPMD document.
I can check later today or latest over the week end. I can make a proposal and some guys with a cabling network can verify.
Looking forward to figure out how we can fill this gap.
Best regards
Peter Fischer
SwissBES GmbH
On 04/07/2025 10:52 PM CEST George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx> wrote:
I need some help here from cabling/industrial guys… The way we wrote the mode conversion requirement in D2.2 looks like one requirement, “The mode conversion loss… shall meet the values of Equation…” but then levies it on 2 different cabling specifications – TCL and ELTCTL. Usually these are different, no? Should they be?
George Zimmerman, Ph.D.
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications
george@xxxxxxxxxxxxxxxxxxxx
310-920-3860
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