RE: [EFM] Minutes of FEC Conf Call, 10/23/02
Larry,
I was actually attending the meeting also, but I got there late (about 15
min) and left early. I was in the lab making measurements and time got away
from me, as happens when one is having fun.
One of the things I did was to charactize a FP laser as the temperature
changes. Going from -40C to + 80C the center WL changes, as we know, but the
power also drops significantly and the mode structure changes. I think one
should not compensate for falling power-out in making BER measurements, as
this will happen in practice.
I was not able to get reliable BER figures as the BERT tester was giving
results that I do not trust. I was getting bursts of about 500,000 errors
every 20 or 30 seconds. It was also very difficult to get consistent BER
readings as the slope of the BER curve seemed very steep.
Another potential "problem" was that (if I ignore the above-mentioned
bursts) even with 40Km of fiber I was getting almost error-free performance
over the whole temperature range except for the -40C value. (This was with
an average power out of the laser of about .7 dbm and no added attenuation
other than the fiber. Afterall, I wanted to be in the MPN dominated region
of operation).
Unfortunately it may be a while before I get back in the lab.
John
-----Original Message-----
From: owner-stds-802-3-efm@majordomo.ieee.org
[mailto:owner-stds-802-3-efm@majordomo.ieee.org]On Behalf Of larry
rennie
Sent: Thursday, October 24, 2002 5:13 PM
To: EFM TF
Subject: [EFM] Minutes of FEC Conf Call, 10/23/02
Attendees:
Meir Bartur, Zonu
Jonathan Thatcher, Worldwide Packets
Eric Lynskey, UNH IOL
Bob Noseworthy, UNH IOL
Lior Khermosh, Passave
Masoud Khansari, Centillium
Larry Rennie, National Semiconductor and FEC Chair
1. Discussed CDR test methodology being implemented by UNH IOL.
Revised previous scheme proposed by UHH. The scheme now will measure
the time it takes an off-the-shelf 1G SERDES to lock and output correct
data when its input is electrically switched from a loopback mode to an
input from a GBIC receiving data at various BER's.
2. As Meir pointed out, the lock time in point 1 will have a statistical
distribution over the number of trials so the experiment, for each BER,
will have to be done over enough trials to determine the distribution
(say 10 to 100 times) and its sigma value.
3. Ideally, it would be best if the input BER on the fiber is a mainly a
result of MPN generated noise. Right now UNH is generating the BER
using an optical attenuator which should provide some useful initial
results.
4. MPN testing to start at Zonu within the next week or so.
5. Presentations at the November meeting tentatively cover:
a) Results of work done by UNH and Passave on optimizing the FEC framing
format.
b) FEC Test Status.
c) Additional FEC details from Passave
6. It was suggested that it would be nice if we could have a draft of
the FEC Clause ready for a vote by the TF at the November meeting. It
is understood that producing such a Clause in the remaining time will
have a lot of holes but can draw upon applicable FEC work contained in
other standards (for example, code description, etc.).
Action Items:
1. UNH IOL to provide a block diagram and description of the new CDR
test scheme.
Larry
larry rennie wrote:
> Date: Wednesday, October 23, 2002
> Time: 1:00 p.m. (EST) = 10:00a.m (PST)
> Duration: 1 hour
> Chair: Larry Rennie, National Semiconductor
> Dial in: 1-800-331-8016 (toll free), 1-816-650-0666 (direct)
> Participant code: 744004
>
> Hosted by EFMA.
>
> Proposed Agenda/Discussion:
>
> 1. CDR low BER Testting. Status.
>
> 2. MPN low BER testing. Status.
>
> 3. Presentations for November EFM meeting..
>
> Larry