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Re: [BP] ATCA Test Channels / FEXT



john,

     Does this mean that you are planning on recommending a change to
the ICR spec?

                      charles

DAmbrosia, John F wrote:
> All,
> 
> Rich Mellitz and I were reviewing the channels being discussed, and were 
> reviewing the crosstalk aggressors.  We discovered a potential issue 
> with the FEXT data submitted for the ATCA channels.  In Tyco’s data it 
> is assumed that the two FEXT aggressors are equivalent, while in the 
> Intel data the FEXT data was generated where all aggressors came from 
> the same line card.  For a real ATCA system the two above scenarios are 
> incorrect.  In the ATCA system channels are based on the 8 differential 
> pair from a single line card to the fabric.  Thus, if you look at the 
> fabric a single Rx pair would be hit on one side from an aggressor 
> originating from the same line card and another aggressor originating 
> from a different line card.  From initial simulations Rich has done, the 
> value of FEXT in a net where a single connector is shared is 
> significantly lower than a case where two connectors are shared.  
> Therefore, one of the FEXT aggressors is probably less than what was 
> originally anticipated.  Tyco is currently modifying line cards to 
> provide test data that shows this effect.  Hence, we should gain some 
> further margin for ATCA applications by reducing one of the 3 
> contributors. 
> 
> Cheers!
> 
> John D'Ambrosia
> 
> 


-- 
|--------------------------------------------------------------------|
|       Charles Moore
|       Avago Technologies
|       ISD
|       charles.moore@avagotech.com
|       (970) 288-4561
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