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Mike and Marek, Sounds like the 1577 is the exception, not the 1590. -Victor From: Marek Hajduczenia
[mailto:marek_haj@xxxxxxx] Hi Mike, thanks for sharing Your point of view with us. Please confirm whether I understand You right. You say that we
should go with a wider window and carriers may require vendors to actually
build equipment which complies to a certain part of this sub-band. In our case,
we could hypothetically specify a downstream band between 1574 and 1600 nm
while e.g. a narrow band option between 1574 and 1580 nm could be required by
some carriers to remain compliant with their ODN. Is this what You're trying to
relay in Your email ? Please confirm Thank You Marek From: Mike Dudek [mailto:Mike.Dudek@xxxxxxxx] As an outsider to 10GEPON, but member of IEEE 802.3 working group
I’d like to suggest that the IEEE standard should be working to provide the
best solution for the new future installs of the IEEE standard while paying
attention to the existing infrastructure. When you come
to a point that you are having to drive the cost of the new standard higher in
order to be compatible with existing infrastructure that may or may not exist
in many applications I’d suggest that the IEEE standard should work for the
long term low cost solution, while making it technically feasible for people
with the existing infrastructure to add additional requirements to make it
compatible with their existing infrastructure. That way you do not
burden the long term cost of new installs. EG if the
low cost solution needs a Tx window of xnm to x+30nm but for compatibility with
a non-IEEE standard can only be xnm +10nm, then the IEEE spec should be xnm to
x+30nm and individual vendors that are using the non-IEEE standard can impose
the tighter (subset spec) of xnm to xnm +10nm. (This obviously only
applies if the PAR and objectives have not made compatibility with the non-IEEE
standard a requirement.). Please note my example is for
illustration only the numbers in it are not meant to apply to this specific
question. From: Jim Farmer
[mailto:Jim.Farmer@xxxxxxxxxxxxx] My primary concern is that the 1577 nm downstream wavelength is
inconsistent with use of the 1550 nm broadcast (auxiliary) wavelength.
The problem is that the two wavelengths are too close together to allow us to
build economical filters at the ONU to separate the two wavelengths. It
is a little easier with the 1590 nm wavelength, though it is still difficult.
Originally I wanted to specify the wavelength band as 1580 - 1600 nm as it was
originally. But I found that when I put in real filter characteristics, I
still had an extremely narrow transition region for the filter. So I
accepted that we would have to narrow the transmit window. I chose +/-3
nm (1587 - 1593 nm) following the reasoning for PR(X)30. We are adding
cost to the laser, but at the OLT, which is not as cost sensitive as is the
ONU. I also had to accept that the auxiliary wavelength was limited to
1550 - 1555 nm, even though commercial practice is to use wavelengths up to
almost 1560 nm. People may complain about this restriction, but I think
in the end they will live with it. Unfortunately I have not been able to get quantitative information
on the filter complexity - I would like to see filter vendors jump in with
comparative numbers. Some vendors I spoke with gave me more pessimistic
numbers than I used in preparing the slides. So the application is for anyone who wants to use the 1550 nm
broadcast wavelength. This is the only way I see to possibly make use of
1550 nm overlay practical. And it still demands a more difficult filter
than we demand currently. But presumably advances in the state-of-the-art
will made the filter practical at some point. Thanks, jim Jim Farmer,
K4BSE From: Frank Chang [mailto:ychang@xxxxxxxxxxx] I just reviewed this thread, and my interpretation to Jim’s slides
is that- 1) The
argument is not for PR(X)30 as cooled TX is assumed because of tight power
budget, so narrower 1577nm band considered feasible for PR(X)30. 2) For
PR10/20, possibly uncooled optical sources are assumed, so bring about the
argument that larger wavelength band, such as wider 1590nm band, is only
feasible. To satisfy this argument, basically call for the group to switch
back to the wavelength plan originally specified in D2.0. So actually we are
re-visiting the argument the group made during the baseline stage a year ago. Jim- Can you confirm this is what you are looking for? As it is clear the PR(X)30 will be assumed mainstream deployment
which requires co-existence with installed 1G version, can anybody elaborate
the scenarios on how PR10/20 going to be deployed? My question is weather
PR10/20 scenarios has to use cooled or semi-cooled optical source?
] thanks Frank C. From: Frank Effenberger
[mailto:feffenberger@xxxxxxxxxx] To pile onto this thread, I have a question regarding Jim Farmer’s
most recent presentation and Maurice’s support of it: Did you notice that Jim’s presentation is asking to change the
PR10/20 OLT transmitter wavelength range to 1587 to 1593nm? (At least, that is how I read it, but I should say that the exact
numbers are not clear.) Perhaps Jim can clarify exactly what he is asking for… that would
be helpful. Sincerely, Frank E> From: Marek Hajduczenia
[mailto:marek_haj@xxxxxxx] Hi Maurice, Just following the arguments You used in Your email: does that mean
that You see PR(X)20 OLT transmitters as uncooled devices? Are the power levels
we are targeting achievable using uncooled optics? As far as I understand,
cooling is necessary not only to keep the central wavelength within the
predefined range but also assure higher output power level. Can You comment on
this? Regards Marek From: Maurice Reintjes
[mailto:maurice.reintjes@xxxxxxxxxxxxx]
We
request to make the attached presentation during the 10GEPON meeting in Dallas.
We remain concerned over the decision to drop the 1590 nm downstream band
from the plan, for reasons shown in the attached. Note that there are
notes that go with most of the slides. You can see them by going to
View|Notes Page Thanks, Jim
Farmer, K4BSE |