| Thread Links | Date Links | ||||
|---|---|---|---|---|---|
| Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
|
Gian Marco – I assume that when you said “Broad R Reach” below, you meant 100BASE-T1 (per IEEE 802.3bw), as reflected in Conrad’s email below. It is probably better for all to avoid trade names, especially if there is a relevant IEEE specification. -george From: Zerna, Conrad [mailto:conrad.zerna@xxxxxxxxxxxxxxxxx]
Hi Gian Marco, I noticed that discrepancy, too.
As far as I know, the 802.3bw has not considered the capacitive coupler, just the stripline.
The transfer function of the stripline is 9.54dB lower at 10MHz than at the plateau between 30MHz and 200MHz. If you keep your CM-termination at 25Ohm, your plateau is ca. -8dB. Therefore, you CM-Limit becomes 21dBµV/10kHz+8dB+9.54dB=38.54dBµV/10kHz. If you increase your CM-termination to 120Ohm, your plateau is ca. -14dB. Therefore, you CM-Limit becomes 21dBµV/10kHz+14dB+9.54dB=44.54dBµV/10kHz. Now, you have a limit, which your (calculated below) CM signal of the 802.3bw spec passes … I just read the spec document for emissions tests and applied the different sections to the system, because they both have limits for frequency bands, which the current 10SPE waveform occupies. The final statement, if both of these tests equally apply or how they must be satisfied, should come from an OEM … ! Regards, Conrad Von: Gian Marco Bo [mailto:gian_marco.bo@xxxxxxxxxxxxxx]
Good morning Conrad, I read the presentation related the comments 148, 149, and 155 (http://www.ieee802.org/3/cg/public/Mar2018/zerna_3cg_02a_0318.pdf). According stripline and capacitive coupler tests, you calculate what should be the maximum amount of common mode signal to fit both test limits. If I consider (for the sake of simplifity) 10MHz, the common mode limit signal is 33dBuV. Now if PSD@10MHz is -65dB/Hz (10MHz RBW) or -25dBm or 85dBuV, considering -43dB of mode conversion (always @ 10MHz), the resulting common mode signal is 42dBuV and this is higher than the limit you compute. In the same way, considering 33dBuV as common mode signal limit and 43dB mode conversion (always 10MHz), the resultinmg PSD limit is 76dBuV, or -34dBm, or -74dBm/Hz (10KHz RBW). PSD@10MHz must be smaller to fit the limit you consider. I am wondering if same consideration can be done for BroadR Reach. According specification, at 10MHz PSD must be between -24dBm and -33.2dBm, i.e., higher than the -34dBm limit previously defined. Should we miss something ? Best Regards. Gian Marco Bo To unsubscribe from the STDS-802-3-10SPE list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-10SPE&A=1
To unsubscribe from the STDS-802-3-10SPE list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-10SPE&A=1 To unsubscribe from the STDS-802-3-10SPE list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-10SPE&A=1 |