Dear Joseph: Thanks for your reply. The equation is from section 47.4.1 Compliance interconnect definition, not 47.41, it's my mistake. I entirely agree to your idea. The compliance interconnects' performance is not a goal, it is a limit. My confusion is at the equation, I thinks it should be that: |S21|>=|S21|limit, ISI loss<4dB, this channel may be within the "compliance interconnect" or the "confidence region", but my ideal is just opposite with the XAUI Compliance interconnect definition which is |S21|?|S21|limit=-20log(e)*[a1*f^2+a2*f+a3*f^2] ISI loss>4dB 2012/5/8 <Joseph.Schachner@xxxxxxxxxx> > The equation you gave is from section *47.4.1 Compliance interconnect > definition.* > There is no section 47.41. > > The way to understand this is to understand what the Compliance > interconnect is used for. It is used for "compliance testing" of a XAUI > signal from a PHY. It is meant to be about as bad as an interconnect is > allowed to be. It is used for making measurements on the transmitted > signal. In the next section, 47.4.2. it says far end Eye Diagram template > tests are measured "at the end of the compliance interconnect specified > in 47.4.1." (It also defines the load to be used at the far end for > this test, separately). > > The intent is to show that the transmitted signal can pass the far end > template after an interconnect at least this bad. Any system that you > make is expected to have BETTER (or equal, at worst) s21 than the > compliance interconnect. Your short channel, with much less s21, is > great! > > A compliant PHY's transmitted signal can pass the far end eye after going > through the "compliance interconnect". This means: > If a channel is worse than the compliance interconnect, then the testing > defined in 802.3 doesn't guarantee that the system with that channel will > work. > If a channel is better than the compliance interconnect - like your short > channel - then the testing defined in 802.3 is supposed to guarantee that > the system will work. > > In short: the compliance interconnects' performance is not a goal, it is > a limit. > > That is my understanding. > > --- Joe S. > [image: Inactive hide details for Edison Green ---05/08/2012 08:56:08 > AM---I am confused when I study XAUI SPEC which in the Cause 47.4]Edison > Green ---05/08/2012 08:56:08 AM---I am confused when I study XAUI SPEC > which in the Cause 47.41 of IEEE standard 802.3 > > > > From: > > > Edison Green <edisonluckforever@xxxxxxxxx> > > To: > > > si-list@xxxxxxxxxxxxx > > Date: > > > 05/08/2012 08:56 AM > > Subject: > > > [SI-LIST] XAUI - How to understand the "Compliance interconnect definition" > > Sent by: > > > si-list-bounce@xxxxxxxxxxxxx > ------------------------------ > > > > I am confused when I study XAUI SPEC which in the Cause 47.41 of IEEE > standard 802.3 > > > The Compliance interconnect definition describe as follow: > > > > |S21|~|S21|limit=-20log(e)*[a1*f^2+a2*f+a3*f^2] > > This limit applies from DC to 3.125 GHz. The magnitude response above 3.125 > GHz does not exceed -11.4 dB > > > > ISI loss>4dB > > The ISI loss,defined as the difference in magnitude response between two > frequencies, is greater than 4.0 dB between 312.5 MHz and 1.5625 GHz. > > > > > > My question is that: > > If my interconnect is shorter and the insertion losses(S21) is small also, > it maybe can't satisfy the "Compliance interconnect definition". > > My interconnect charactar S21 will be > >|S21|limit=-20log(e)*[a1*f^2+a2*f+a3*f^2] > > ISI loss will be <4db according to the definition(because abs(S21) may > <4db) > > > > In my mind, the shorter , the better, is it wrong? > > How to understand the "Compliance interconnect definition"? > > ------------------------------------------------------------------ > 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: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List forum is accessible at: > http://tech.groups.yahoo.com/group/si-list > > List archives are viewable at: > //www.freelists.org/archives/si-list > > 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: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu