[SI-LIST] Re: XAUI - How to understand the "Compliance interconnect definition"
- From: Edison Green <edisonluckforever@xxxxxxxxx>
- To: Joseph.Schachner@xxxxxxxxxx
- Date: Wed, 9 May 2012 10:50:20 +0800
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"?
>
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