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Re: [BP] EoBP Thru model Rev 5

Title:
Mike, Stephen,
    Here is a plot of s31 after reading thru_rev5.s4p into matlab.  The nonlinear phase I'm talking about are the three big slope changes in the phase starting around 3.125GHz.  From looking at the file the frequency is in MHz, and the data is in amplitude (magnitude) / phase (in degrees) pairs.  I'm also assuming that the s4p file format is standard :
line 1: f, s11, s12, s13,s14
line 2: s21,s22,s23,s24
line 3: s31,s32,s33,s34
line 4: s41,s42,s43,s44

are these assuptions all correct?

Howard Baumer


Altmann, Michael W wrote:
Stephen, Howard,

In general, phase non-linearity is the source of pulse dispersion and
asymmetry.  In fact any real, causal, lossy and dispersive channel (i.e.
copper) always has some non-linearity in the phase response (however
small).

Subtracting the linear term of the phase is equal to reducing the bulk
delay of the channel to zero (retains the pulse shape intact, though).
Considered another way, the linear component (of phase) is the baseline
for the group-delay variation plot we have been debating.

.../Mike

-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of Stephen
D. Anderson
Sent: Thursday, August 26, 2004 6:51 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] EoBP Thru model Rev 5



    Howard:

    I think what you are seeing is related to the non-causal effects
that
I described in a previous e-mail to the reflector.  This is being fixed.
I'll send out a new revision when it's done.

    Thanks.

    Regards,

    Steve A.


"Howard A. Baumer" wrote:

  
Steve Anderson,
    I noticed in the model that is posted on the EoBP web site that
    
the
  
phase is not linear.  This causes a lot of ringing in the impulse
response.  Every backplane that I have delt with over the last few
    
years
  
always has linear phase.  The model that was labeld thru6 and dated
early July had linear phase.

Howard Baumer

JPEG image