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AW: [802.3ae_Serial] Jitter experiments




Hi Piers ,
Unfortunately I may be miss the call today, at least it is likely I am late.
I do not have measurements about actual penalties yet, however we confirmed
the resulting SJ tolerance values for other transponders.
As soon as I have the penalties (sensitivities under different amount of
jitter I will communicate them)
Regards Juergen

	----------
	Von:  piers_dawe@xxxxxxxxxxx [SMTP:piers_dawe@xxxxxxxxxxx]
	Gesendet:  Dienstag, 11. Dezember 2001 17:10
	An:  Rahn, Juergen (Juergen)
	Cc:  stds-802-3-hssg-serialpmd@xxxxxxxx
	Betreff:  RE: [802.3ae_Serial] Jitter experiments


	Juergen,

	Thank you, that's valuable information.

	Was the optical power near to the receiver sensitivity (with the
sinusoidal
	jitter turned off) or well above it?

	Piers

	> -----Original Message-----
	> From: Rahn, Juergen (Juergen) [mailto:krahn@xxxxxxxxxx]
	> Sent: 11 December 2001 15:47
	> To: 802. 3ae Serial PMD (E-mail)
	> Subject: AW: [802.3ae_Serial] Jitter experiments
	> 
	> Hi,
	> we have continued the measurements measuring the tolerance 
	> for other error
	> rates. What we found under the conditions already used was 
	> that the limits
	> where nearly identical as for 10 to -10- This confirms the errors
we
	> measured were related nearly complete to the SJ of a bit 
	> above 0.4 UI (there
	> was no significant random component visible) . This confirms 
	> for me that
	> looking purely on the  horizontal component this determines 
	> the limits of
	> the CDR under nominal conditions.
	> It should be noted that this is a typical Lab environment 
	> test with few
	> different modules, BOL room temperature typical. I am sure 
	> some margin is
	> required to account for extreme temp drift, aging drift, and 
	> supply voltage
	> tolerance. This all is not specified by the third party 
	> modules we used in
	> this particular measurements. 
	>  We are now trying to measure what this would mean in terms 
	> of penalty to
	> estimate what would be possible under real conditions. 
	> Regards Juergen. 
	> 
	> 	----------
	> 	Von:  Rahn, Juergen (Juergen)
	> 	Gesendet:  Montag, 3. Dezember 2001 18:18
	> 	An:  802. 3ae Serial PMD (E-mail)
	> 	Betreff:  AW: [802.3ae_Serial] Jitter experiments
	> 
	> 
	> 	Hi all,
	> 	Sorry for not being able to participate on the last 
	> call (I have a conflict
	> 	tomorrow too). However I want to give some interim info 
	> about tests on
	> 	jitter we did. We used a SDH test set for jitter based 
	> on the ITU
	> 	definitions. So we measured the  broadband jitter 
	> generation and tolerance
	> 	in the frequency domain between 4 and 80Mhz. However as 
	> concerning the
	> 	tolerance it is not likely that a system is more 
	> tolerant to jitter at
	> 	frequencies even higher above the PLL border the 
	> results may give some
	> 	understanding of the underlying principles.
	> 	We used commercial transponders as available on the 
	> market. We measured the
	> 	generation and tolerance w/o fiber to be free of 
	> influences of fiber effects
	> 	(Which may be traded off in the future) (TP2=TP3). The 
	> Jitter generation of
	> 	random jitter of the Transponder was at the measurement 
	> limit and smaller
	> 	than the jitter comming out of the Test set. (Which gives me
the
	> 	understanding that all this was clock jitter that will 
	> be further reduced by
	> 	the PLL an the parallel stream. There was no visible DJ 
	> on the scope of the
	> 	transmitted signal. Under these conditions we observed 
	> a tolerance for a BER
	> 	of about 10 to -10 of a bit above 0.4 UI P-P sinus 
	> jitter, which was nearly
	> 	equal to total jitter as stated before, nearly constant 
	> for frequencies
	> 	above PLL border frequency. We will repeat those tests 
	> for other error rates
	> 	to get an understanding how the theoretical bathtub may 
	> look like (as we
	> 	used commercial modules we have no way to shift the 
	> sampling point through
	> 	the eye) and get an understanding about the penalty 
	> induced by which jitter
	> 	amplitude. It should be noted that the penalty in the 
	> measurement we did was
	> 	real big, and so I do not believe at al that if we have 
	> at 0.4 UI P-P (of
	> 	whatever waveform the jitter follows) a penalty that 
	> eats up a big part of
	> 	the budget we see the nominal sensitivity at 0.35 UI. 
	> (So this somewhat
	> 	confirms the measurements from Intel) I will come up 
	> with more dedicated
	> 	results.
	> 	Regards Juergen
	> 
	> 
	> 
	> 
	> 		----------
	> 		Von:  Lindsay, Tom
[SMTP:tlindsay@xxxxxxxxxxxxxxxxxxxx]
	> 		Gesendet:  Samstag, 1. Dezember 2001 01:21
	> 		An:  802. 3ae Serial PMD (E-mail)
	> 		Betreff:  [802.3ae_Serial] Jitter experiments
	> 
	> 		This email is in response to my committment on 
	> the 11/27/01 serial
	> 	PMD con-call. This is still very crude, and I apologize 
	> for lack of
	> 	appropriate thought, but hopefully it can stimulate 
	> more discussion.
	> 		****
	> 		 
	> 		A major concern for 10G serial is 
	> instrumentation error for doing
	> 	jitter measurements. Steve's Buchheit's work clearly 
	> demonstrates this.
	> 	Ideally, instrumentation will improve sufficiently to 
	> allay this concern,
	> 	but none of us expect that to occur sufficiently in 
	> advance of deployment.
	> 	So if we are to keep the basic definition and method 
	> for jitter measurement,
	> 	then we require agreed upon means to compensate the 
	> instrumentation.
	> 		 
	> 		With this in mind, I simply brainstormed 5 
	> categories of test
	> 	settings and measurements, with the hopes (dreams?) 
	> that differences in
	> 	their results can provide insight into how compensation 
	> can be achieved.
	> 		 
	> 		1. Measuring instruments
	> 		  Scope - eye patterns w/ crossing histograms
	> 		  Error detector - jitter bathtub
	> 		 
	> 		2. Configurations (essentially the same used by
Steve)
	> 		  Pattern generator to measuring instrument
	> 		  Pattern generator through E/O and O/E to 
	> measuring instrument
	> 		  Pattern generator through stress conditioning 
	> and E/O and O/E to
	> 	measuring instrument
	> 		  Pattern generator through DUT and O/E to 
	> measuring instrument
	> 		 
	> 		3. Test patterns
	> 		  Pattern 1
	> 		  Pattern 2
	> 		  PRBS31
	> 		  00 00 00 00 00 00 00 03 FF FF FF FF FF FF FF 
	> FD (isolated 1,
	> 	isolated 0)
	> 		  Repeating CC (square wave with 50% transition 
	> density, same as
	> 	average PRBS)
	> 		 
	> 		4. Signal variations
	> 		  rise/fall time (at least 2 levels of slow/fast)
	> 		  amplitude (at least 2 levels of low/high)
	> 		 
	> 		5. Stress conditioning mechanisms
	> 		  high frequency ISI/DDJ
	> 		  low frequency BLW/DDJ
	> 		 
	> 		At this point, I do not know if there is a path 
	> through this that
	> 	will lead anywhere (this is the apology again...). I 
	> hope someone else can
	> 	determine if there is really any value in here. The 
	> 5-dimensional matrix
	> 	results in a large number of test combinations - too 
	> many. A Design of
	> 	Experiments may be required to reduce the set. 
	> Obviously more directed
	> 	experiments can be defined with some risk of missing 
	> key information.
	> 		 
	> 		Tom Lindsay 
	> 		Stratos Lightwave, NW design center
	> 		425/672-8035 x105
	>