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Hi all, I have some comments to Piers’s presentation dawe_062718_02_3cd_adhoc provided at yesterday’s cd ad hoc call. Piers stated on slide 4
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In D3.3, the implied unstressed sensitivity for 50GBASE-SR (100 m) is about -7.3 dBm
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After converting optical power to photocurrent, this is equivalent to 50GBASE-LR (10 km) and 1.5 dB harder for the receiver than 50GBASE-FR
(2 km)
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As well as much higher stress levels (higher TDECQ and residual penalty
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This is the wrong way round! The very short reach PMD should be easier and lower power I would like to refresh everybody’s mind on a presentation I gave at the July 2017 meeting in Berlin: http://www.ieee802.org/3/cd/public/July17/stassar_3cd_01_0717.pdf It demonstrated how much margin we have for the 50G FR/LR Rx and that we had the luxury to choose someone in the middle between reasonable Tx and
Rx levels. We demonstrated Rx sensitivities (probably SECQ non zero) of better than -12 dBm, whereas the requirement for SECQ < 1.4 dB would be -6.9 dBm for
50GBASE-FR and -8.4 dBm for 50GBASE-LR. If you compare this with -6.5 dBm for 50GBASE-SR then there really is no issue and one would probably just make another optimization because of VCSEL
Tx power levels being at another optimum point than for SMF Tx. Furthermore the requirements in Clauses 138 – 140 are: 50GBASE-SR: RS = max(–6.5, SECQ – 7.9) (dB) 50GBASE-FR: RS = max(–6.9, SECQ – 8.3) (dB) 50GBASE-LR: RS = max(–8.4, SECQ – 9.8) (dB) I still read that SR has most relaxed Rx sensitivity, then FR 0.4 dB better and LR again 1.5 dB better. Kind regards, Peter Peter Stassar,
施笪安
Technical Director,
技术总监
Huawei Technologies Ltd,
华为技术有限公司 European Research Center,
欧洲研究所 Herikerbergweg 36, 1101 CM Amsterdam The Netherlands Tel: +31 20 4300 832 Mob: +31 6 21146286 To unsubscribe from the STDS-802-3-50G list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-50G&A=1 |