15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 1 Teleconference notes, 15 Dec 2004 Jonathan King

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 2 Agenda 1)Attendees 2)Agree last meetings minutes 3)Task 2 a)no agenda items 4)Launch study, joint task 2 & task 4 a)Al Brunsting - Connector lateral offsets b)John Ewen - OM3 PIE Metrics with connectors c)Jonathan King - measured PIE-D vs launch for OM3 fibres d)Joerg Kropp - OM3 Fibre EFD PIE-D e)Discussion of draft launch recommendations 5)other business 6)next meeting date/time

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 3 1) Attendees Jonathan King, Big Bear Networks Yu Sun, Optium John Jaeger, Big Bear Networks Joerg Kropp, Infinion David Cunningham, Agilent Sudeep Bhoja, Big Bear Networks John Ewen, JDSU Jim Morris, DOC Al Brunsting, Panduit Andre van Schyndel, Bookham Lew Aronson, Finisar Gary Schaulov, Petre Popescu, Quake Petar Pepeljugoski, IBM Lisa Huff Paul Kolesar, Systimax

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 4 2) Last meetings minutes agreed No issues raised 3) Task 2 - no agenda items

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 5 4) Launch study, joint activity task 2 & a) Connector lateral offsets - Al Brunsting A comprehensive analysis of mechanisms contributing to connector offset was presented; measurements of 3050 MMF ferrules from 4 suppliers gave mean offsets of between 2.5 and 3 microns, and 95% cumulative frequency values of between 4.8 and 6.1 microns. Discussion following General consensus was that this work showed solid validation of the 7 micron worst case connection offset chosen for link modeling. b) OM3 PIE metrics with connectors - John Ewen (ewen Simulations showing 99 percentile PIE-D metrics vs single-mode launch offset on OM3 and FDDI fibres. For OM3 fibres, centre launch gave lowest PIE-D with (PIE-D=4.8dB) and without (PIE-D=3dB) 2 offset connections before the main link; For FDDI fibres, OSL was a slightly better launch with high offset connections, although centre launch could give lower PIE-D for no offset connections. Discussion following 10 mode groups were used in the 50micron fibre simulations, which was agreed to be reasonable when differential mode group attenuation was taken into account. An initial finite width single-mode launch was assumed, and the simulations take into account 47.1ps transmitter rise time and 7.5GHz Rx filter. Petar Pepeljugoski confirmed that the maximum offset launch permitted by modal noise considerations 18um for 50um core fibre. Petar also commented that faster transmitter risetimes could lower PIE-D values significantly.

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 6 4) Task 2 & 4: joint activity on launch study - 2 c) PIE-D measurements on OM3 fibres - Jonathan King PIE-D measured on TIA 2.2demo fibre reels (OM3), showing single mode centre launch launch gave significantly lower PIE-D than 13umOSL, both with and without 7um offset connection before the main link; PIE-D for a 'native' multimode centre launch was also shown, without connection offset. Discussion following Comments on the 'native' multimode launch measurements - a 'native' launch generally injects power into a wider spread of modes than a single-mode launch; an encircled flux test was suggested as a way to control higher order mode group excitation. Lew Aronson comment was made that measurements of PIE-D for native centre launch with connection offsets would be valuable. Paul Kolesar commented that a second high offset connection after the main link did not have a significant effect on the PIE-D, and a second high offset connection would makje the PIE-D as bad as a 13um offset launch; it was noted out that a high offset connection before and after the link was closer to a legacy link, and that two 7um offset connections before the link would look more like a single 9um offset connection.

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 7 4) Task 2 & 4: joint activity on launch study - 3 d) OM3 Fibre EFD PIE-D - Joerg Kropp Joerg compared impulse response and fibre bandwidths of an ideal model of OM3 with some measured OM3 fibres: an alpha-p value of 2.1 was a good fit to measurements. Centre launch gave better fibre bandwidths than offset launches. Encircled flux vs radius plots were also presented, which allowed provisional encircled flux values to be extracted for various launches. Group discussion following this presentation lead smoothly into the next agenda item : e) discussion of the draft launch recommendations Discussion following It was generally agreed that some form of centre launch gave best PIE-D for OM3 fibres. For OM1 and OM2 fibre it was felt there may be greater link coverage if both centre launch and OSL were permitted, which would be consistent with what happens in the field for 1GigE. However, several participants felt that formalizing this in a standard was not easy: LX was specified to be into a single-mode input fibre on a mode conditioning patchcord, whereas LRM would ideally be implementation non-specific. After some discussion, a way forward was agreed which included describing recommended primary launches by encircled flux definitions at TP2, with definitions consistent with single-mode centre launch and single-mode offset launches for OM1, OM2 and OM3. It was agreed to add footnotes which gave example implementations for each launch definition, and to avoid a coupled power ratio test which was felt to too inaccurate. Consequences for a 'universal' launch were also discussed; it may require the distance spec on one of the fibre types to be reduced, but could provide cost savings. Jim Morris offered to present some work on a universal launch at the next meeting; Lew Aronson offered OM3 and universal launch measurements with offset connections at the next meeting.

15 Dec 2004IEEE802.3aq Channel model ad hoc Task 2: Time-varying study & modal noise 8 5) Next meeting Wednesday 5th January am PCT 4) Other business - no issues raised