RE: [10GBASE-T] channel model
Pirooz,
The data I sent out was based upon measurement to 500 MHz. The model was extrapolated from 500 MHz to 1.0 GHz. Because of limitations in my current measurement setup, I cannot validate the proposed model beyond 600 MHz. The attached graph compares the measured data beyond 500 MHz to the proposed model. I have a very high degree of confidence in the model below 500 MHz.
Because of the low signal levels and test fixture imperfections, it becomes significantly more difficult to make accurate insertion loss measurements on a 100 meter channel above 500 MHz. These measurement difficulties also exist for crosstalk measurements, especially the FEXT measurement.
Regards,
Larry
-----Original Message-----
From: Pirooz Hojabri [mailto:pirooz@platolabs.com]
Sent: Wednesday, January 29, 2003 3:40 PM
To: Larry Cohen; William Jones; stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] channel model
Larry,
Thanks, for the plot and data. Using your data and Class D&E equations, we
have ploted the channel up to 1GHz{see attached(channel1G.doc)}.Please
compare this plot with your measurement data beyond 500 MHz. Do you have
measurement data from DC to 1 GHz?
If this is a reasonable representation of the channel from DC to 1GHz, then
it can be used for feasibility study simulations.
regards,pirooz
Plato Labs,Inc
Pirooz Hojabri
V.P Mixed Signal
408-379-4900
> Attached is a proposed 100 meter Cat 5e channel model for 10GBaseT
> study (CHANMOD.TXT). This model is defined by complex-valued (X +
> jY format) insertion gain in the at 500 kHz intervals from DC to 1
> GHz.
>
> The proposed model is derived from measurement (at 20 C) of a 100
> meter channel (with Cat 5e patch cords and 4 Cat 5e RJ45 connector
> interfaces). The baseline 100 meter channel model was temperature
> corrected to 50 C. (122 F.) using the procedure defined in ASTM
> D4566 Section 26.4. The above mentioned temperature correction
> method modifies the magnitude but not the phase of the insertion
> loss. Experimental measurements confirm that temperature effects on
> the phase are minimal so the approximation is sufficiently accurate.
>
> The most recent proposed model is an extrapolation of the ISO 11801
> Class D channel loss limit. The ISO 11801 Class D limit is designed
> to accommodate expected worst-case measurements below 100 MHz and
> consequently includes some additional margin to meet this
> requirement. Since this limit is only specified below 100 MHz,
> extrapolation of the limit through smooth curve fitting becomes
> less accurate as it is extended farther beyond its defined
> boundaries. The new proposed model is based upon measurements
> beyond 500 MHz and thus validated to at least 500 MHz (and somewhat
> beyond 500 MHz). As shown in the attached graphs (CHANMOD.DOC), the
> insertion loss for the proposed model differs from the ISO 11801
> Class D 2002 channel limit by less than 0.2 dB from DC to 50 MHz and
> less than 0.5 dB from 50 to 100 MHz. While it does not represent an
> absolute worst-case channel, it represents a reasonable model for a
> feasibility study simulating a maximum length channel under worst-
> case temperature conditions.
>
> -Larry
>
> -----Original Message-----
> From: William Jones
> Sent: Wednesday, January 22, 2003 11:19 PM
> To: stds-802-3-10gbt@ieee.org
> Subject: RE: [10GBASE-T] channel model
>
> Xiaopeng
>
> How are the calculations coming? Are you using the models Chris
> sent out last week?
>
> regards
> Bill
>
> -----Original Message-----
> From: William Jones
> Sent: Wednesday, January 15, 2003 4:08 PM
> To: stds-802-3-10gbt@ieee.org
> Subject: [10GBASE-T] channel model(part 2)
>
> Bill,
>
> Sure. Once the common channel model (I only need the frequency
> domain characteristics) is available, I can begin to work on it.
>
> Regards,
> Xiaopeng
> ----------
>
> Xiaopeng
>
> Would you be willing to sign up for technical feasibility based on an
> optimal DFE calculation?
>
> regards
> Bill
> -----------
>
> Bill,
>
> I has no problem to use TIA or ISO based channel and noise model
> once it is standardized. My point is that even using the frequency-
> domain model we can still give a quite good estimation of the
> practically achievable distance at a throughtput of 10Gbps over CAT-
> 5E or CAT-6 cables.
>
> Regards,
>
> Xiaopeng
> -------------
>
> Xiaopeng
>
> We believe, as George discussed in his part of the tutorial in Kauai,
> that with an adequate amount of crosstalk cancellation, the
> throughput is achievable. The question then becomes can this level
> of cancellation be practically achieved, hence, my interest in time
> domain models.
>
> Until we get the models from the channel modeling Ad Hoc, we could argue
> this point endlessly. Until then, I still believe we should not use
> DSL models, but, rather something from TIA 568b or ISO 11801.
>
> regards
>
> Bill
ildata.doc