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Hi Matt, Thanks for your response. I made comments in-line. Kind regards, Peter From: Matthew Schmitt [mailto:m.schmitt@xxxxxxxxxxxxx]
Peter, WRT meeting the application of 80km without optical amplifiers, from a practical POV you’re probably correct, although depending on how you define meeting the application it might be possible. To show what I mean, I thought it might be
useful to go through some numbers. We’ve generally been using an assumption for loss in fiber (including loss due to splices and other imperfections) of 0.25 dB/km; that means that to reach 80km we would expect to experience 20 dB of attenuation. If you add in another dB
of loss for connectors, etc., you’re at 21 dB of attenuation. Our minimum requirement for tx output power is -8 dBm, and our minimum requirement for receive sensitivity when OSNR is high (when there’s no optical amplifier present) is -30 dBm, a difference of 22 dB. Therefore, technically you can
just marginally make 80km, albeit with no other sources of loss (not realistic) and no DWDM muxes (possible in some cases: even though we’re required to support working with DWDM muxes in a DWDM system, it won’t always be the case). Peter: well, this is a single channel application not meeting the objective of “operation on a single wavelength capable of at least 80 km over a DWDM system”. The fact that you may be able to do what you suggest is outside the scope of this clause. If you do want to do 80km over a DWDM system with 40 channels, then it would seem unavoidable to use optical amplifiers.
That’s how the specification is constructed, which is indeed also in a way to allow the applications you described. However, we also allow for tx output power levels of 0 dBm. That would now give us 30 dB to work with, or 9 dB remaining after accounting for distance loss and connectors. With a reasonable allotment for other impairments and a pair of
muxes with a relatively low attenuation (a 16 channel mux should result in 3dB of attenuation each, if memory serves), 80 km is achievable in that case without an optical amplifier. Peter: that is an engineered solution using higher powers than specified. In an interworking situation one cannot assume power levels higher than the minimum of -8 dBm. So for the application you described
you need tighter specifications than currently in Clause 154. Now, whether or not that qualifies as meeting our application of 80km without an optical amplifier I am not sure – I will defer to other experts on that – but as I said, I thought it would be worthwhile to go through the numbers. Peter: as I tried to imply, from my point of view it doesn’t. Thanks.
From: Peter Stassar <Peter.Stassar@xxxxxxxxxx> Hi John, Thanks. The specification is uni-directional from TP2 to TP3, not pre-cluding bi-directional operation. I would be surprised if you could meet our application of 80km without OAs. Kind regards, Peter From: John DeAndrea [mailto:John.DeAndrea@xxxxxxxxxxx]
Hi John, Steve and Peter, One comment on the proposed remedy, Page 2. Bullet 1.
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Term “”unidirectional” This term is technically valid for black links which include optical amplifiers. Typically, isolators are used within optical amplifiers, which creates the uni-directional behavior. Our use case for black link
also includes implementations without optical amplifiers. In those use cases, the passive mux and demux filters, and cable plant, would support bi-directional optical carriers. Therefore, you might consider dropping the term ‘unidirectional” as one option,
or clarification on this aspect in the text. Regards, John DeAndrea From: John D'Ambrosia <jdambrosia@xxxxxxxxx>
All, At last week’s meeting we did not finish comment #83, which discussed the black link methodology.
Please see the attached presentation that will be discussed on Thursday that seeks to close out Comment #83. Please use the reflector to discuss the presentation to assist in reaching consensus and closing comment. My thanks to my co-authors – Steve / Peter for helping to progress this. Regards John D’Ambrosia To unsubscribe from the STDS-802-3-DWDM list, click the following link:
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