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Re: [802.3_4PPOE] Your proposal for Single-signature definition in

Hi Yair,

But it does work...

If a voltage is applied to the corrupting pairset, a single-signature
PD will "not show a valid detection signature" because Rdetect will be
outside the limits of Table 145-21.

If a current is applied to the corrupting pairset, a single-signature
PD will "not show a valid detection signature" because Voffset will be
outside of the limits of Table 145-21.

Both corrupting methods are viable.

Kind regards,


On Mon, 2017-11-06 at 15:02 +0000, Yair Darshan wrote:
> Hi David,
> I have reviewed your proposal and I see that the current injection
> method may not work if you are looking for invalid signature i.e.
> 25K.
> The reason is that when you inject two current levels in mode A (I1,
> I2 and e.g. I1>I2) and find valid signature (25K) on that mode while
> the current on mode B is 0, and then you inject new current level I3
> on mode B while you keep I2 in mode A, you will get valid slope of
> 25K (I am ignoring the offset voltage for now) which means it shows a
> valid signature (25k) while I supposed to get invalid signature (in
> terms of resistance and no other parameters that defines invalid
> signature).
> In general, any current you inject on mode B when mode A is
> conducting will just generate offset voltage across Rsig but will not
> change the slope of Rsig=25K. The reason for it is that detection is
> done always in differential way (two values of current or voltage)
> which cancel offsets.
> The best approach to define single-signature PD is to use the voltage
> concept. It will always work. Please remember that the way we define
> the PD is it single-signature or not should not imply and doesn’t not
> imply how we implement connection check. Moreover, I am also
> suggesting adding a text that say it explicitly.
> To summarize:
> I prefer the following definition:
> A single-signature PD shall present a valid detection signature, as
> defined in Table 145-21, on a given Mode when no voltage or current
> is applied on the other Mode, and shall present an invalid not
> present a valid detection signature on that Mode when any voltage
> between 10.1V and 57V at least one voltage between 3.7V and 57V is
> applied to the other Mode or any current greater than 124μA is
> applied to the other Mode. These requirements apply to both Mode A
> and Mode B.
> This definition doesn’t imply on the way how connection check is
> implemented weather using voltage or injecting current.”
> NOTE—A valid detection signature meets every requirement in Table
> 145-21 across all specified conditions. A failure under any allowed
> conditions of Table 145-21 is considered “not a valid signature while
> “invalid signature” is when the requirements of Table 145-22 are
> met. 
> Darshan Yair
> Chief R&D Engineer
> Analog Mixed Signal Group
> Microsemi Corporation
> 1 Hanagar St., P.O. Box 7220
> Neve Ne'eman Industrial Zone
> Hod Hasharon 45421, Israel
> Tel:  +972-9-775-5100, EXT 210.
> Cell: +972-54-4893019
> Fax: +972-9-775-5111
> E-mail: <mailto:ydarshan@xxxxxxxxxxxxx>.