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
>