[SI-LIST] Re: Estimate ISI with S parameters -- Using TDR to do SDD21 correlation?
- From: steve weir <weirsi@xxxxxxxxxx>
- To: "Zhiping Yang (zhiping)" <zhiping@xxxxxxxxx>, <scott@xxxxxxxxxxxxx>
- Date: Mon, 16 May 2005 23:31:55 -0700
Zhiping, I doubt Scott meant that one can get the whole matrix with just
S11 with just a single far end measurement configuration. If he did and
has a way to do that, he has me beat.
I assume that Scott meant given S11 measurements for all conditions: far
end shorted, far end open, and far end terminated, with decent resolution
above the measurement noise floor that the full matrix can be derived. I
guess we will find out when he wakes up in a few hours.
Regards,
Steve.
At 11:01 PM 5/16/2005 -0700, Zhiping Yang \(zhiping\) wrote:
>
>Hi Scott and others,
>
>Sorry that MS Outlook messed up my previous e-mail. Here I resend it
>again.
>
>I can not agree with your statement that S11 contains all the
>information that you need to characterize a channel. In order to
>completely characterize a two-port channel, the complete S2P matrix is
>required. In the real application, it is OK to use TDR (S11) to
>construct a channel model, but this model may not be unique and it may
>have different S21/S12 and S22 for different models. It is not
>difficult to find a simple example to prove it. Thanks.
>
>Best regards,
>
>Zhiping
>
>*******************************************
>
>John
>
>In theory, S11 contains all the information that you need to
>characterize a channel, as does a TDR waveform. In practice, S11 is an
>extremely sensitive to all discontinuities and losses in the channel.
>Since it is a round trip measurement, every feature in the channel has
>twice the impact on the returned waveform. If the reflected waveform
>that you measure has a reasonable match to your simulated waveform, then
>you're in the right "ballpark." But there's nothing like a good TDT or
>insertion loss measurement to know exactly how well the system will
>perform.
>
>regards,
>
>Scott
>
>Scott McMorrow
>Teraspeed Consulting Group LLC
>121 North River Drive
>Narragansett, RI 02882
>(401) 284-1827 Business
>(401) 284-1840 Fax
>
>http://www.teraspeed.com
>
>Teraspeed(r) is the registered service mark of Teraspeed Consulting
>Group LLC
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