Thread Links | Date Links | ||||
---|---|---|---|---|---|
Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
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 thatthephase is not linear. This causes a lot of ringing in the impulse response. Every backplane that I have delt with over the last fewyearsalways has linear phase. The model that was labeld thru6 and dated early July had linear phase. Howard Baumer |