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RE: From serial PMD call, 15 May




Tom,

At present the draft standard, and the link model, start with the unfiltered
rise time.  The link model converts this into 10-90% rise time in box P4,
"Ts(10-90)", which is used (box F14 and column F) to create filtered 10-90%
rise times in box G14, ("Tc" at 2 m) and column G.  These are used to
calculate ISI and other penalties.

I hope that this addresses your question,

Piers

> -----Original Message-----
> From: Lindsay, Tom [mailto:tlindsay@xxxxxxxxxxxxxxxxxxxx]
> Sent: 17 May 2001 23:50
> To: DAWE,PIERS (A-England,ex1); 802.3ae Serial
> Subject: RE: From serial PMD call, 15 May
> 
> 
> Piers - In FC, the present ristime spec is without a filter, however a
> filter may be used (not required) to pass the mask test.
> 
> The concern is about risetime being too slow (the low jitter case); I
> don't think anyone is worried about it being too fast. It may not have
> large effect, but testing against a mask with a filter will 
> require the
> source to have a faster risetime than if measured without a filter.
> Which scenario are you considering? Which case (of both) have been
> considered in the link model?
> 
> Thanks,
> Tom Lindsay
> Stratos Lightwave
> 425/672-8005
> 
> 
> -----Original Message-----
> From: DAWE,PIERS (A-England,ex1) [mailto:piers_dawe@xxxxxxxxxxx]
> Sent: Thursday, May 17, 2001 10:29 AM
> To: '802.3ae Serial'
> Subject: From serial PMD call, 15 May
> 
> 
> 
> Discussion of proposed deletion of risetime spec. line for 1310 serial
> ----------------------------------------------------------------------
> We inherited this from Fibre Channel.  SONET don't have it.  Fibre
> Channel
> have discussed removing it, without strong views either way.  
> Piers with
> help from Petar and support from others will present how we can live
> without
> it.
> 
> Chromatic dispersion penalty
> ----------------------------
> Our modelled number is unrealistic for two reasons:
> 	Spectral width is likely much less than the 0.4 nm model number
> 	Dispersion penalty is worked out for an incoherent source and
> ours
> is coherent.  In Petar's terms, we are using a power model 
> and we should
> be
> using a field model.
> Luckily these two effects would move the error in opposite directions
> and we
> are discussing a penalty of only ~0.5 dB.  This is thought to be
> pessimistic.
> 
> Comments on Draft 3.0
> ---------------------
> We had more reviewers than last time which is good.  Clause 52 has
> collected
> about 200 comments including 34 TRs.
> 
> Next meeting
> ------------
> There will be no meeting on 22 May.  Will likely restart at the usual
> time
> on 29 May:
> 	15:15 GMT = 4:15 pm BST = 17:15 CET = 11:15 am EDT = 8:15 am
> PDT,
> Tuesday (today)
> 	+1(816)650-0631  Access code 39209
> Piers
>