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[802.3_SPEP2P] AWGN crosstalk models for PHY Evaluation - was RE: mixed 10BASE-T1L/100BASE-T1L Crosstalk



All – attached is my homework item, with a few things for us to discuss.  I have included both a proposed evaluation noise model for equal-length long-line 100BASE-T1L.  I have also included a proposed evaluation model for mixed crosstalk with 10BASE-T1L.  The first uses a single AWGN source, the second, a sum of 2 sources.

 

The presentation also highlights the importance of dealing with the near-far problem in 100BASE-T1L.  For those unfamiliar, disturbing signals coupling in as FEXT sources on short links can create substantially greater crosstalk.  This is especially important when PSAACR-F coupling is strong, as it is here.  I recall from the excellent contributions we have seen that PSAACR-F couples at the marshalled connectors in process automation plants.  While I generally agree with Peter, and want to handle all conditions without management, this is a particular situation where it may be that a little configuration management (or use of modular connectors rather than screw terminals) could save some significant trouble in the PHY and also improve the impulse resistance of all links.  I’m counting on the experience of our participants familiar with the operating environment.  Note – we all know we can solve this with cabling, but here it is especailly important to hear from those who are familiar with the operators and installers of systems.

 

Feel free to email me if you have questions.

-george

 

From: Peter Jones (petejone) <petejone@xxxxxxxxx>
Sent: Monday, January 29, 2024 4:26 PM
To: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>; STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: RE: mixed 10BASE-T1L/100BASE-T1L Crosstalk

 

George,

 

I strongly agree with you.

 

We should be striving to recreate the success of the BASE-T ecosystem, and that means accepting a mix of multiple speeds in the environment.

 

Regards

Peter

 

_______________________________________________________________

Peter Jones               Distinguished Engineer,

                          Cisco Networking Hardware

                          Chair, Ethernet Alliance

Mobile:                   +1 408 315 8024

Email:                    petejone@xxxxxxxxx

Web:                      https://about.me/petergjones

Webex:                    https://cisco.webex.com/meet/petejone

Book a call:              Peter's booking page

_______________________________________________________________

 

 

From: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Sent: Monday, January 29, 2024 10:40 AM
To: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: [802.3_SPEP2P] mixed 10BASE-T1L/100BASE-T1L Crosstalk

 

All – in generating a noise environment, it occurs to me that the low frequency noise might be substantially different if we consider an environment with some 10BASE-T1L and some 100BASE-T1L disturbers. (I have substantial experience in mixed crosstalk environments from prior work, both in Ethernet and DSL systems).  This tends to increase the noise at low frequencies and could be important.

 

My own experience tells me such installations would likely be commonplace; however, I would like to ask other practitioners their experience, particularly whether they would likely see the inline connector distributions of the two technologies mixed in an operational process automation scenario.

It isn’t a huge effect, but if this happens, including it can be a useful way to avoid putting too little low frequency noise.

 

George Zimmerman, Ph.D.

President & Principal

CME Consulting, Inc.

Experts in Advanced PHYsical Communications

george@xxxxxxxxxxxxxxxxxxxx

310-920-3860

 


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