FreeLists / si-list / [SI-LIST] Re: Definition of "crosstalk loss" ??

[wolfgang.maichen@xxxxxxxxxxxx]

I have to admit I haven't heard that term myself before. But from the text 
it looks like they mean the signal loss in the agressor - keep in mind 
that the crosstalk signal (energy) in the victim has to come from 
somewhere, so if there is to be a crosstalk signal on the victim, then the 
agressor must experience signal loss. Loss in aggressor signal voltage is 
often not as easily visible, for two reasons. Since power is proportional 
to the square of the voltage, a 1% energy loss due to crosstalk amounts to 
only an approx. 0.5% reduction in aggressor signal. In addition, it's 
easier to observe the crosstalk on the victim going from e.g. 0 to 10mV - 
a large relative change - than it is to observe the aggressor signal going 
from 1000mV to 995mV - a very small relative change -, which can hide the 
effect in practical scope measurements and lead to the false belief that 
crosstalk only affects the victim but not the aggressor.
Wolfgang






agathon <hreidmarkailen@xxxxxxxxx> 
Sent by: si-list-bounce@xxxxxxxxxxxxx
12/04/2007 05:01 PM
Please respond to
hreidmarkailen@xxxxxxxxx


To
si-list <si-list@xxxxxxxxxxxxx>
cc

Subject
[SI-LIST] Definition of "crosstalk loss" ??






Hello all,
I'm trying to make clearer the following statement from 802.3ap:

"...FEXTn is the crosstalk loss, in dB, of aggressor n."

What the heck is "crosstalk loss"????


The full paragraph is:

69B.4.6.2 Power sum differential far-end crosstalk (PSFEXT)
The differential far-end crosstalk at TP4 is calculated as the power sum 
of
the individual FEXT aggressors
(PSFEXT). PSFEXT is computed as shown in Equation (69B?16), where FEXTn is
the crosstalk loss, in dB,
of aggressor n. Note that for the case of a single aggressor, PSFEXT will 
be
the crosstalk loss for that single
aggressor.


Thanks,
Agathon

 ------------

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at: 
                                 http://www.freelists.org/archives/si-list
or at our remote archives:
                                 
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                                 http://www.qsl.net/wb6tpu
 



------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu