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[802.3_SPEP2P] AW: S parameter for 500m channel



Dear François

 

I fully agree, ELTCTL is more relevant. It would be good to have all parameters measured at different lengths, in our case 500 m and 100 m, which are not linearly scaled with IL. For RL, I cannot give you typical link configurations, normally we use up to 4 connectors for 100 m, the maximum length of 500 m may consist of 5 connectors if I remember our goals correctly. The input should come from PHY manufacturers on which link configurations they see as most critical to run simulations.

 

Best regards

 

Peter Fischer

Head Business Solution & Innovation

 

www.bks.ch

 

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Automatisch generierte Beschreibung

 

signature_297452691

 

Von: Francois Beauregard <Francois.Beauregard@xxxxxxxxxx>
Gesendet: Donnerstag, 7. März 2024 17:16
An: Peter Fischer <p.fischer@xxxxxx>; STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Betreff: RE: S parameter for 500m channel

 

Hello Peter,

 

TCTL vs. ELTCTL

We published TCTL earlier in 2023 because the Insertion Loss of the cable prototype was not smooth above 60 Mhz.  I am sorry that we didn’t update the plot with the new 500m test datas.  But ELTCTL is more relevant.

TCTL = Scd21(dB)

ELTCTL = Scd21 (dB) – Sdd21 (dB)

Did you mean that it should be valuable to measure S-parameters at different lengths?  In order to assess parameters that cannot be assumed linearly scaled with IL?

 

RL

The measurements were done on a single piece of 500m cable, no connectors.  For simulation purpose, we could define typical link configurations and add connectivity impairements.

 

 

Francois Beauregard 

 

 

 

From: Peter Fischer <p.fischer@xxxxxx>
Sent: Thursday, March 7, 2024 8:54 AM
To: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] [802.3_SPEP2P] AW: S parameter for 500m channel

 

External Message:Use caution before opening links or attachments

Dear François and all

 

I have few questions:

  • Why do you use TCTL instead of ELTCTL? For me scaling is not only related to IL, therefore a 100m measurement for the short link case would be more accurate.
  • RL looks for me too good, at least after installation we cannot expect such values.

 

Best regards

 

Peter Fischer

Head Business Solution & Innovation

 

www.bks.ch

 

Ein Bild, das Zeichnung enthält.

Automatisch generierte Beschreibung

 

signature_297452691

 

Von: Francois Beauregard <00002cfd85cd2c3d-dmarc-request@xxxxxxxxxxxxxxxxx>
Gesendet: Dienstag, 5. März 2024 17:37
An: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Betreff: Re: [802.3_SPEP2P] S parameter for 500m channel

 

Hello Georges,

 

These are a new set of S-parameters for 18AWG-500m cable;  the phase issue has been corrected by doing interpolation above 32Mhz.

 

 

Sdd, Scd, Sdc : S2p touchtone formatted, 125kHz to 100 MHz, step 125kHz

SPE100 : excel format Sdd11, Sdd22, Sdd21, Scd11, Scd22, Scd21, 125kHz to 100MHz, step 125kHz

 

Regards

 

Francois Beauregard

 

From: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, February 27, 2024 5:22 PM
To: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] Re: [802.3_SPEP2P] S parameter for 500m channel

 

External Message:Use caution before opening links or attachments

Francios – did you compare the phase response?  That was what tingting mentioned in her email.  Sometimes phase responses (particularly at low frequencies) get messed up due to various processing techniques.  These are important for extracting time-domain simulations.  They also are a bit tricky to scale properly with length.

 

From: stds-802-3-spep2p@xxxxxxxxxxxxxxxxx <stds-802-3-spep2p@xxxxxxxxxxxxxxxxx> On Behalf Of Francois Beauregard
Sent: Tuesday, February 27, 2024 2:06 PM
To: zhangtingting (O) <zhangtingting59@xxxxxxxxxx>; STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: RE: S parameter for 500m channel

 

Hello Tingting,

 

I scaled down the 500m measurements to 100m.  The IL was found to be in good agreement with the model proposed by Voss/Wachtel

 

 

Regards

 

Francois Beauregard

 

From: zhangtingting (O) <00001e92abc91102-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Monday, February 19, 2024 8:46 PM
To: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] [802.3_SPEP2P] S parameter for 500m channel

 

External Message:Use caution before opening links or attachments

Hi,

 

I found that the phase calculated from the real and imag of S21 in the online Excel seems to weird. Besides, the frequency step is 0.125MHz for frequencies less than 32MHz, and increases to 0.25MHz after 32MHz. If the correct measurement data of 500m channel is not available, LT Spice model has to be used to get S parameters for time domain simulation.

 

The online presentation associated with the LT Spice model is wrong (incorrect link). Do the inline connectors need to be included for the 500m channel, or just cascade five 100m segments?

 

Thanks

 

 

 

Best wishes,

Tingting


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