Re: [10GMMF] Dynamic test (was: TP3 3-impulse test proposa)l
Sorry, I have no background on GR-63-CORE.
jonathan
> -----Original Message-----
> From: owner-stds-802-3-10gmmf@IEEE.ORG
> [mailto:owner-stds-802-3-10gmmf@IEEE.ORG]On Behalf Of Jonathan King
> Sent: Tuesday, September 21, 2004 6:55 PM
> To: STDS-802-3-10GMMF@listserv.ieee.org
> Subject: Re: [10GMMF] Dynamic test (was: TP3 3-impulse test proposa)l
>
>
> Hi Jonathan
> thanks for the very interesting observations
> I guess that this is the kind of environment that GR-63-CORE seeks to
> describe and test for... what do you think ?
> best wishes
>
> Jonathan
>
> tel: 1 408 524 5110
> e-mail: jking@bigbearnetworks.com
> fax: 1 408 739 0568
>
> Jonathan King
> Director, Optical Systems
> BigBear Networks
> 345 Potrero Avenue
> Sunnyvale, CA 94085
>
>
> -----Original Message-----
> From: Jonathan Thatcher [mailto:jonathan.thatcher@IEEE.ORG]
> Sent: Tuesday, September 21, 2004 10:45 AM
> To: STDS-802-3-10GMMF@listserv.ieee.org
> Subject: Re: [10GMMF] Dynamic test (was: TP3 3-impulse test proposa)l
>
> As I walked through a data center this morning with thousands
> of cables
> (very many MMF), it was obvious to me that the major case for movement
> of
> the fiber is the vibration caused by -- literally -- the 10's of
> thousands
> of fans (yes, it is the case that a relatively small number of these
> affect
> a specific fiber. I would guess this to be related to those that are
> most
> closely coupled. There may be as many as 100 of these).
>
> Based on the grab the cable or cable bundle test and become
> one with the
> fiber, it seems that the majority of the vibration occurs at the
> connector
> and within the first 10's of centimeters from the connector.
> This is not
> what I first expected. It does make intuitive sense.
>
> This vibration, of course, is continuous during the operation of the
> equipment.
>
> Presuming the vibration I can detect is sub 10KHz (more likely sub 1
> KHz),
> it represents a whole lot of bits per vibration period.
>
> I have no way to validate this. But, I presume that since there is no
> attempt to design it out there may well be a sampling of
> these that are
> actually vibrating at a harmonic with respect to the cable/connector
> assembly.
>
> Ain't life fun.
>
> jonathan
>
> > -----Original Message-----
> > From: owner-stds-802-3-10gmmf@IEEE.ORG
> > [mailto:owner-stds-802-3-10gmmf@IEEE.ORG]On Behalf Of Lobel, Martin
> > Sent: Tuesday, September 21, 2004 1:57 AM
> > To: STDS-802-3-10GMMF@listserv.ieee.org
> > Subject: Re: [10GMMF] Dynamic test (was: TP3 3-impulse test
> proposa)l
> >
> >
> > Jonathan,
> >
> > I fully agree with your observations from the lab (moving the fiber
> > several centimeters etc.) and the fact that building vibrations will
> > only lead to minor movements of fiber.
> >
> > My comments are, however, a reflection of slide 11 of the TP3
> > presentation sent out on the reflector on Sep. 17th by Ben Willcocks
> > which suggests that we should use a dynamic test that shifts from
> > post-cursor to pre-cursor at 1 KHz. I believe that this is not
> > reproducing any real-life scenario and could be too stressful
> > to the EDC
> > solution.
> >
> > For a given installed fiber, I believe that two things can
> > happen to the
> > fiber/connector in a link:
> >
> > 1) The fiber undergoes vibrations due to building movements.
> > 2) The fiber is moved (bend or twisted) by personnel during
> > installation
> > of other hardware, daily cleaning etc.
> >
> > My comment is related to 2) which can cause (in line with your
> > observations in the lab) large changes in the channel impulse
> > response.
> > I don't know the nature of such changes but believe they
> can be large
> > but with a longer time scale than vibrations (how fast can
> you move a
> > fiber by hand). I believe that it is vital to study these
> > nature of such
> > large changes and ensure that any dynamic test covers the 2) case.
> >
> > I'm looking forward to the report out from the Task 2 to
> > understand more
> > about the physical behavior of the channel.
> >
> > Thanks,
> > Martin
> >
> >
> > **************************************************************
> > *********
> > Martin Lobel, M.Sc.E.E., Ph.D.
> > Standards and Advanced Technology
> > Intel Copenhagen ApS
> > Mileparken 22
> > DK-2740 Skovlunde
> > Denmark
> > Phone (direct): +45 44 54 61 33
> > Cell phone +45 27 22 62 37
> > i-net: 8-2966 133
> > Phone (switch board): + 45 70 10 10 62
> > Fax: +45 70 10 10 63
> > email: martin.lobel@intel.com
> > **************************************************************
> > *********
> >
> > -----Original Message-----
> > From: owner-stds-802-3-10gmmf@IEEE.ORG
> > [mailto:owner-stds-802-3-10gmmf@IEEE.ORG] On Behalf Of Jonathan King
> > Sent: 21. september 2004 01:48
> > To: STDS-802-3-10GMMF@listserv.ieee.org
> > Subject: Re: [10GMMF] TP3 3-impulse test proposal
> >
> > Hi Martin
> >
> > I have a comment on the TP3 dynamic response test.
> >
> > I expect that the TP3 dynamic test will need to be
> significantly below
> > 1kHz rate if it is to be realistic.
> >
> > Task 2 is actively studying time variation effects, and is
> > basing tests
> > on GR-63-CORE which is an existing standard describing appropriate
> > operational testing for in building environments. It describes
> > vibration testing from 5Hz to 100Hz, with constant
> > acceleration stimulus
> > (0.1g and 1g accelerations). For constant acceleration, the
> > amplitude of
> > vibration decreases with the square of the frequency, for example:
> >
> > At 5Hz and 1g acceleration, vibration amplitude is 2 cm
> peak to peak,
> > comparable to a rather fast fibre shaker as described in
> > TIA/EIA-455-203;
> > At 50Hz and 1g acceleration, vibration amplitude is 0.2
> > millimetres peak
> > to peak;
> > At 500Hz and 1g acceleration, vibration amplitude is 2
> microns peak to
> > peak;
> >
> > I think its common experience in the laboratory that large
> changes in
> > IPR occur only when a fibre coil is distorted by several
> centimetres,
> > with relatively insignificant changes in IPR at displacements
> > much below
> > 1mm.
> > I expect this will place an upper bound on the test frequency in the
> > ~10Hz range
> >
> > best wishes
> >
> > Jonathan
> >
> > tel: 1 408 524 5110
> > e-mail: jking@bigbearnetworks.com
> > fax: 1 408 739 0568
> >
> > Jonathan King
> > Director, Optical Systems
> > BigBear Networks
> > 345 Potrero Avenue
> > Sunnyvale, CA 94085
> >
> >
> > -----Original Message-----
> > From: Lobel, Martin [mailto:martin.lobel@INTEL.COM]
> > Sent: Monday, September 20, 2004 3:47 AM
> > To: STDS-802-3-10GMMF@listserv.ieee.org
> > Subject: Re: [10GMMF] TP3 3-impulse test proposal
> >
> > All,
> >
> >
> >
> > A)
> > From a practical implementation point of view, it makes a
> lot of sense
> > to limit the number of 'taps' to a minimum (three so far).
> As pointed
> > out by Lew, I'm also concerned that the limited time span of the
> > stressor (2xdT=200 ps) will not be a good emulation of real
> > life channel
> > impulse responses even that the PIE are alike.
> >
> > Many we should consider to have two tests with different dT(?). It
> > could, e.g., be implemented with 5 taps total.
> >
> > B) Comments on the dynamic test: The biggest problem for real EDC
> > solutions may not be to handle the ~KHz variation (1 KHz has been
> > suggested) but more the problem of been able to handle the
> variety of
> > channel responses and make the transition from one response 'A' to
> > another channel response 'B' without causing errors.
> >
> > The question is if we can imagine that any given Cambridge channel
> > response may be followed by any other arbitrary Cambridge Channel
> > response due to vibration of the fiber and/or connectors. If
> > the answer
> > is 'no' then the suggested dynamic test of going from a state with
> > completely pre-cursor only to a new state with completely
> post-cursor
> > only may be a too stressful test that may lead to a non-desirable
> > trade-offs for the implementation.
> >
> > Regards,
> > Martin
> >
> >
> >
> > -----Original Message-----
> > From: owner-stds-802-3-10gmmf@IEEE.ORG
> > [mailto:owner-stds-802-3-10gmmf@IEEE.ORG] On Behalf Of Lew Aronson
> > Sent: 17. september 2004 21:02
> > To: STDS-802-3-10GMMF@listserv.ieee.org
> > Subject: Re: [10GMMF] TP3 3-impulse test proposal
> >
> > I think this is very close to where we want to be for the dynamic
> > penalty test, and I see no reason why the three impulse response
> > functions can't be aligned with those used for the static test. A
> > number of different comments:
> >
> > 1) We should do this calculation (and all similar
> > calculations) for 300m
> > as well as 220m.
> >
> > 2) It is interesting to come up with 1.0 UI for the dT. In
> a way that
> > is good in that I know that many consider that a pretty
> > demanding case,
> > so if it makes sense with the fiber model and EDC makers consider it
> > realistic to pass, than on that basis it might be a good choice.
> >
> > 3) I am concerned about deriving the details of the impulse response
> > parameters solely from PIE metrics. The reason is that PIE
> is for an
> > infinite ideal equalizer. As such, it's sensitivity to the
> total time
> > span of the impulse response is presumably a lot flatter (and more
> > non-monotonic) than is the performance of a real finite
> equalizer. I
> > think we see this in that the final choice in the values was not
> > terribly sensitivie to dT and was chosen to get a close fit
> on the PIE
> > value for the -D and -L cases simulataneously.
> >
> > Thus, we risk coming up with a choice which is too short
> (compared to
> > actual fiber response) to adequately stress a real
> implementation, or
> > vice versa. Even worse, our choice is likely to drive the design
> > tradeoffs of the EDC's used and thus should really match
> the dT spands
> > from the fiber models.
> >
> > I would suggest that, at least in the case of the dT
> choice, that the
> > fiber models and Petre's work be used to determine the approximate
> > choice, and that we live with a larger difference in PIE-L and PIE-D
> > that results.
> >
> > 4) With that said, I think the idea of having the same dT and the
> > pre-cursor and post cursor symmetric to each other is
> probably a great
> > goal for the static test as well and would then naturally align the
> > static and dynamic tests. [This would not change my thinking
> > on the fact
> > that the static and dynamic tests should be seperate, I would
> > still have
> > many reasons to want that]. Petre's work so far has emphasized the
> > goodness of fit to particular fiber examples. In the end,
> I think we
> > just want to have something of the same general shape chosen to
> > represent the 99% point by a combination of PIE value and
> > represnetative
> > dT values, and to use that extra freedom to have equal dT's between
> > pulses and cases if at all possible.
> >
> > Thus, I would say that we want to wind up with something of
> > the form Ben
> > has given us, but with the dT and perhaps a value motivated more by
> > Petre's work than by the most exact fit to PIE numbers.
> >
> > Lew
> >
> > Lew Aronson (lew.aronson@finisar.com)
> > Finisar Corporation
> > 1308 Moffett Park Drive
> > Sunnyvale, CA 94089-1133
> > 408-542-4215 (PH)
> > 408-543-0083 (FAX)
> >
> >
> > -----Original Message-----
> > From: Ben Willcocks [mailto:ben.willcocks@PHYWORKS-IC.COM]
> > Sent: Friday, September 17, 2004 8:13 AM
> > To: STDS-802-3-10GMMF@listserv.ieee.org
> > Subject: [10GMMF] TP3 3-impulse test proposal
> >
> >
> > Further to the preliminary data I presented in the phone
> > conference of 7
> > September, I have attached slides showing our TP3 3-impulse test
> > proposal & simulation results. Many thanks to Sudeep Bhoja for his
> > assistance regarding the PIE calculations.
> >
> > With Mike's permission, I would like to talk through this
> during next
> > Tuesday's TP3 conference call.
> >
> > Regards,
> >
> > Ben
> >
>