Re: [10GBT] Request for Cat6 Emissions Characteristics
Title:
Hi
Jose, All;
I
agree that EMI characteristics of UTP "as a general rule" increase with
frequency but I don't think its as easy as applying a simple 20log10(f) curve to
the PSD. Depending on cable geometries, ground plane and component balance, the
performance of a cable plant will most likely not have such a smooth
function.
Therefore, its not quite so easy to say that PAM12 is
better than PAM8 based strictly upon Jose's assertion. If you look at the figure
below, you will see that PAM12 is higher in the range from 100MHz to 180MHz and
both are above 1000BASE-T's spectrum in that region.
The
FCC/CISPR don't really care if you pass their specs at 600MHz if you are failing
at 180MHz.
Rather
than drive a conclusion from this data, one expects the rational approach would
be to determine this is an issue that requires attention/resolution prior to
making *any* selection. Maybe the problem is not which PAM to use, but which
cable to use? (FTP/STP?)
I will
be investigating whether my employer will support some research into this area.
I have access to a 10m chamber and think it would be a worthwhile
investigation.
Thanks
to Sailesh Rao and Vivek Telang for providing the data for this
graph.
Regards,
Dan
