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Re: [10GMMF] Agenda TP3 Meeting Tuesday 7th September

Title: Message
Tom, few comments regarding RIN questions:
  • Every light source exhibits intensity fluctuation due spontaneous emission. In a laser, the cavity makes a selection of wave vector achieving the proper coherence in the emitted spectrum. The cavity does not filter any intensity fluctuation.
  • It is common to model intensity fluctuation as filtered white noise according to the low frequency response of the laser. As a consequence, the intensity noise power spectrum resembles the laser frequency response.
  • The RIN is defined as the ratio of the intensity noise electrical spectral power density to the square of the corresponding photocurrent equivalent (CW condition), therefore the RIN spectrum takes close relationship with the frequency response of the laser module, including relaxation oscillation frequency peaking and package response.
  • RIN power spectrum can be easily measured on MW spectrum analyzer and its probability density is fairly Gaussian.
I am sure this is not a complete answer but at least should fix the modeling background.
Best regards
-----Original Message-----
From: owner-stds-802-3-10gmmf@IEEE.ORG [mailto:owner-stds-802-3-10gmmf@IEEE.ORG] On Behalf Of Tom Lindsay
Sent: Dienstag, 7. September 2004 18:12
Subject: Re: [10GMMF] Agenda TP3 Meeting Tuesday 7th September

All -
Here are 2 thoughts that may be of interest for TP3.
1. For jitter, the current proposal is a single frequency well above the cutoff (supposedly in the 4 MHz range) above the tested CDR's tracking window. The single frequency has been proposed to be somewhere in the 40-80 MHz range.
My only real concern is that a frequency in this range does essentially nothing to ensure tracking of low frequencies. Recall that all outputs are to be tested with a 4 MHz high-pass jitter filter. This requirement runs throughout 802.3ae and XFI. This allows, and indeed was originally motivated by, outputs with significant low frequency jitter.
So, I propose another frequency that assures tracking. I propose 5 UI at 40 kHz. These values are per 802.3ae. I would support a note that suggests such a test could be done at the module or even IC level.
2. For RIN and modal noise, it is not completely clear to (at least) me, what the spectrum and probability density functions are, but we can expect they are not single frequency sinusoidal.
Single frequency sinusoidal has been proposed for its simplicity and history with 802.3ae. These are good reasons. Another fairly simple option to consider would be to replace the sinusoidal term with a PRBS pattern (rate and length TBD, if there is any interest). The PRBS pattern would have a wide(r) spectrum. Unfiltered, this would produce a bi-modal density function, much like the sinusoidal signal. Filtered, either at the low or high end can affect not only the spectrum, but also the density function. For example, filtering the upper end to 1/20 of its rate results a rather "normal" (but truncated) appearing pdf.
Is there any interest in pursuing this further?
Tom Lindsay
ClariPhy Communications
phone: (425) 775-7013
cell: (206) 790-3240
----- Original Message -----
Sent: Friday, September 03, 2004 8:55 AM
Subject: [10GMMF] Agenda TP3 Meeting Tuesday 7th September

Hi Folks,

Here is the Agenda for Tuesday's Meeting

I am travelling, so Piers has kindly agreed to step in and manage the agenda.

Best Regards


Dial in Details
Meeting Time: Tuesday Sept 7th. 9am CA, 12 NY, 5pm UK, 6pm Germany

International Direct Dial (650) 599-0374
Meeting ID:                     801803

1. Attendee list
2. Review Notes from Last Meeting (Aug 31)
3. Update on Experimental Results Regarding Non-Idealities in E-O-E (Abhijit)
4. Discussion on Parameter Fitting for the ISI Generator (Petre)
        Petre's on-going work is to do the following:-
        o show PIE-L for the Cambridge vs the approximated channels (validate that the channel metric is not significanlty altered)
        o present thinking on how many impulses are requiered and which should be used for testing
                - early thinking from Petre is suggesting that 3 different responses make sense:-
                        a. quasi symmetric
                        b. post-cursor
                        c. pre-cursor
        o present thinking on the relative merits of BT filters, 2 and 3 peak impulse response models

5. Review work list of addtional items
Review progress on the the following stressors:-
        a. Fiber loss/dispersion
        b. Connector loss/dispersion
        c. Time varying factors
        d. Modal Noise
        e. RIN
        f. Jitter
        g. Optical signal conditioning

a., b. and c. could potentially be covered through a combination of the adhoc and Petre's work - is this true?

For d. and e. Lew is going to talk with Infineon folks regarding some analysis on noise powers to represent modal noise and RIN. Abhijit is going to do some thinking on an EDC chips performance with respect to different noise sources and their nature. In particular is it acceptable to emulate the noise source with a single sinusoid?

For f. Ali Ghiasi and Tom Lindsay are both going to review Lew's proposal of testing with jitter applied at a single frequency and propose if this should be changed and what frequencies should be tested.

No discussion on g.

6. Discuss goals for what we can achieve by the September Interim meeting.