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Re: [802.3_100GCU] measuring odd-even jitter



Charles:

Do you have a reference to "phase noise amplification"?

Ed

Dr. Edward P. Sayre, P. E.
North East Systems Asscoiates, Inc.
9 Maple Lane
PO Box 807
Marshfield, MA  02050  USA
[T]: +1-781-837-9088
[C]: +1-978-314-4940
[E]: esayre@xxxxxxxx

-----Original Message-----
From: Charles Moore [mailto:charles.moore@xxxxxxxxxxxxx] 
Sent: Wednesday, August 08, 2012 4:18 PM
To: STDS-802-3-100GCU@xxxxxxxxxxxxxxxxx
Subject: [802.3_100GCU] measuring odd-even jitter

guys,

   All of the standard PRBS patterns have odd lengths.  If the pattern 
twice, every possible transition will occur twice, once as an even 
numbered transition once as an odd numbered transition.  If you measure 
the average jitter (deviation from some ideal, equally spaced transition

time) on all even numbered transitions and the average jitter on all odd

numbered transitions the difference, divided by 2, will be the odd-even 
jitter.  On average the odd and even transitions will suffer the same 
ISI shift and error due to improperly chosen threshold so the difference

will be free from these effects.  This gives a very clean way of 
measuring odd-even jitter.

   One error will occur if there is substantial loss at Nyquist due to 
the mystically named "phase noise amplification", which will expand 
(amplify) odd-even jitter but it will not create it.

                               charles

-- 
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|       Charles Moore 
|       Avago Technologies
|       APD
|       charles.moore@xxxxxxxxxxxxx
|       (970) 288-4561
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