# Re: [802.3_10SPE] Follow up on presentation from 11.Apr.2018 - DM Noise Level

Hello Mr. Ivanov,

To follow-up to your question on the call,  With nodes floating 5cm above ground plane NodeA measured 105mV at 16.67MHz.   Mode conversion for harness was measured at -51dB at 16.67MHz, limit is -43dB.  See page 9 of presentation.  Scale measured CW noise from 105mVpk-pk by 8dB.  That's where I got 263mVpk-pk.  Assuming linearity, for 355mA test level, scale 263*(355/200) = 467mVpk-pk.  In band.   Let's call it 500mVpk-pk or 178mVrms.  Hope this helps.

regards,
Jay Cordaro

On Wed, May 9, 2018 at 3:51 AM, Galin Ivanov wrote:

Dear Mr. Cordaro,

in your presentation, named “Follow-up to 10BASE-T1S Immunity Measurements” from April 11, 2018 you refer to differential noise levels measured – e.g. on pages 7 and 8.

The frequency ranges for those measurements and the evaluation of the results from those span to frequencies much greater than what is defined by the PSD masks found in the current draft of the specification.

Most notably - your worst case is derived at 33 MHz, which according to the above mentioned PSD distribution shall not carry any significant signal power and can be effectively suppressed when evaluating the RX signal quality!

If you re-evaluate your diagram with the PSD distribution of the target signal in mind, then you will see that, according to your measurement results, the significant maximum peak is found at 16 MHz and has not more than 110 mV, according to the diagram found on page 8.

In this relation, the table on page 10 list a value of 126 mV (!?!) as a base for the calculation. Can you please explain the discrepancy?

Even if we accept the table value to be correct, and take into account other possible sources of mode conversion and Xtalk, based on our current data, we don’t see a justified reason to anticipate more than 300 mVp-p of DM noise in the relevant signal band!

Best regards,

Galin Ivanov

Microchip Technology Germany II GmbH & Co. KG

Galin Ivanov

Principal Engineer, AIS Applications Engineering

Tel: +49 (0)721 625 37 335 Fax: +49 (0)721 625 37 119

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