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[EFM] Minutes from PON Optics Telephone Conference - 12th December


Dayton Gadkari
Frank Effenberger
Gerry Pasavento
Glen Kramer
Lior Khermosh
Meir Bartur
Piers Dawe
Tom Murphy
Tremmont Mial


The discussion of the timing parameters for the PON PMD has been narrowed
down to a selection between Option B and Option C.
The laser values for Option C were in place from the original presentation
from Frank Effenberger, i.e. 16 ns. The current values for Option B are
600 ns for laser on/off and 400 ns receiver recovery times. The same
receiver recovery time is also used in Option C. 

The language enveloping the two options needs to be refined so that it is
clear which parameters are negotiable and so on.

Regarding Option B laser times, it was remarked that an off-the-shelf GBE
component will have laser on/off times of the 
order of milli-secs. Adaptation is required to reduce these times to the
requires 600 ns.  The question then goes out to
PMD vendors: What is the difference between manufacturing a PMD with 16 ns
times compared to one with 600 ns?
It would be very useful to have a reply to this question before the
Vancouver meeting.


In the upstream the consensus is, if possible, to have a PMD level signal
detect level. The timing requirements of this signal would be such that
a valid signal is generated a reasonable period before the end of the
shortest possible burst length (e.g. 10%, depends on the timing 
values adopted.) The statement of the protocol people on the call was that
this SD line would not be required for further functions at 
higher layers, i.e. it is there to assist implementers and need not have
stringent timing specifications.

Values for the downstream and upstream SD will be generated in the next
weeks. The value adopted should reflect the
maximum sensitivity, minimum attenuation in the link and Tx off powers.

There was also the following question: Are Tx_On and Tx_OFf field for the
downstream laser and if not, is a laser off 
power spec valid?

Next Steps

Try generate consensus on either Option B or Option C
Feedback from PMD vendors regarding laser on/off times (see above)
Work on text for Options B and C
Generate signal detect values for upstream and downstream and the
corresponding text which
relates the SD timing requirements to the shortest possible burst.
I will distribute some OH's summarising the PMD values and a first draft of
required text

Next Meeting

Thursday 19th Dec with the same details as last weeks call.

All the best