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Dear Colleagues – I have received a request from Piers to re-open comments #149 & #107 which we closed in yesterday’s meeting. He has provided his justification for each below. Per our procedure, I will ask in Tuesday’s meeting if anyone supports Piers’
request for re-opening these comments and take a straw poll, if necessary. IF, AND ONLY IF, the CRG decides to re-open the comment(s), will we then discuss the technical details of the comment. Please look over the justification given prior to the meeting. ~Beth ------------------------------------------------------------------------------------------------------------------------------- Comment #149 - Cl 162.9.3.5 Comment: Transition time is defined by the referenced 93A.5 which refers to 93A.2 which refers to 86A.5.3.3 which says "for electrical signals, the waveform is observed through a 12 GHz
low-pass filter response (such as a Bessel-Thomson response)", and it's dependent on state of emphasis. Suggested
Remedy: Change "Transition time" to "Rise time". Explain that that is 20-80%, unfiltered, as if at neutral emphasis. Coordinate with the maintenance project. Response: REJECT. The terminology is consistent with 93A.5 in both 802.3cd-2018 and the latest 802.3dc draft. Any related changes in the new revision (802.3dc) can be considered once they are incorporated in the next draft. Piers’ Justification to re-open 149 is technical, not just about names. 162.9.3.5 (ERL) refers to 93A.5, which refers to 93A.2, which gives an equation for a Gaussian filter Ht(f) = exp(–2(π f Tr / 1.6832)^2) (93A–46), and says "where Tr is the 20% to 80% transition time (see 86A.5.3.3) of the signal as
measured at TP0a." 86A.5.3.3, Transition time, says: In this annex, transition times (rise and fall times) are defined as the time between the 20% and 80% times, or 80% and 20% times, respectively, of isolated edges. If the test pattern is the square wave with eight ones and eight zeros, the 0% level and the 100% level are as defined by the OMA measurement procedure (see 68.6.2). If the test pattern is PRBS9, the transitions within sequences of five zeros and four ones, and nine ones and five zeros, respectively, are measured. These are bits 10 to 18 and 1 to 14, respectively, where bits 1 to
9 are the run of nine ones. In this case, the 0% level and the 100% level may be estimated as ZeroLevel and ZeroLevel + MeasuredOMA in the TWDP code (see 68.6.6.2), or by the average signal within windows from –3 UI to –2 UI and from 2 UI to 3 UI relative
to the edge. For electrical signals, the waveform is observed through a 12 GHz low-pass filter response (such as a Bessel-Thomson response). NOTE—This definition is not the same as the rise and fall times typically reported by an oscilloscope from an eye diagram, which take all the edges into account. As you see the transition time of a signal depends on its state of emphasis, and the observation filter. In 162.9.3.5 there is no time-domain signal and no definition of its state of emphasis. 1. There isn't a TP0a in Clause 162.
Rich, where is Tr defined at? My understanding is that there is no time-domain signal anyway, but there are S-parameters, and Tr is not defined at any particular place (although we could indicate
where it would be if we wanted to). 2. As 162 is electrical, "the waveform is observed through a 12 GHz low-pass filter response (such as a Bessel-Thomson response)". This is the
wrong bandwidth. Anyway, I believe
Tr doesn't involve a BT observation filter. Using a different name (we use Tr in this clause, and e.g. 85.10.7, Cable assembly integrated crosstalk noise (ICN), calls it "the 20% to 80% rise and fall times Tnt and Tft respectively" (off topic: they aren't rise
and fall times respectively, but NEXT and FEXT aggressor rise/fall times) could be a way out, but we can put that off because it would be best to have a complete solution that Maintenance can use. For this draft, we can say that this "transition time" by
exception doesn't involve an observation filter. ------------------------------------------------------------------------------------------------------------------------------- Comment #107 - Cl 162.9.4.3.3 Comment: Help the reader understand what is going on Suggested
Remedy: Please add the plot of Hhp to Figure 162-5, NSD(f) constraints Response: REJECT. The referenced equation is a simple first order high-pass filter with 6 GHz corner frequency. Plotting this simple, well understood response is unnecessary. Adding to the current plot would detract from the intent of
the plot. Piers’ Justification to re-open As to comment 107, please illustrate the RITT noise loading high-pass filter reference response in the context of the RITT noise loading spectral density mask: yes, we know what a simple first order high-pass filter looks
like. The readers will want to see its relation to the more complicated mask limits in Figure 162–5—NSD(f) constraints. If the editor doesn't do this very minor chore once, he forces each thorough reader to not only draw the simple first order high-pass
filter but also reproduce the two mask limits in Figure 162-5, NSD(f) constraints. ------------------------------------------------------------------------------------------------------------------------------- To unsubscribe from the STDS-802-3-100GEL list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-100GEL&A=1 |