RE: AW: [802.3ae_Serial] Issue with 1500 Power
Juergen,
You are less confused than you say! I have compared my understanding with
yours: see below. There are some editorial/clarity issues and one
outstanding point which is: is the 802.3ae D3.1 ER/EW receive sensitivity
very demanding or expensive?
Piers
> -----Original Message-----
> From: Rahn, Juergen (Juergen) [mailto:krahn@xxxxxxxxxx]
> Sent: 03 July 2001 09:01
> To: 'Mike Dudek'
> Cc: stds-802-3-hssg-serialpmd@xxxxxxxx; 'Ron Miller'
> Subject: AW: AW: [802.3ae_Serial] Issue with 1500 Power
>
>
> Sorry,
> I am still confused.
> You talk about ISI penalty now but this is stated at transmitter power
> anyway and not quantified.
> In the table it reads:
> Launch power (min) in OMA minus TDP * -1.39 dBm
> with a note:
> * TDP is transmitter and dispersion penalty
> up to now I interpreted that we have to consider the
> penalties and than
> compensate the penalties by increasing the power (Whatever
> the penalties
> are) First question is this a correct understanding?
Yes
> If yes you will not have any advantage at the receiver when
> increasing the
> power by the amount of penalty as a penalty represents the decrease in
> sensitivity, so this should add up to zero.
Yes
> (It comes to my mind that the - in this parameter suggests
> that the power
> may be decreased by the penalties which would give trouble
> but this may be a
> short editorial discussion)
Juergen please make a comment. Editor please note!
> If this understanding is correct let me make the calculation:
> Simple case ideal transmitter no penalties :
> Launch power (min) in OMA minus TDP * -1.39 dBm
>
> Stressed receive sensitivity (max) in OMA ?, ? , §
> (-11.40)
> (dBm)
>
> I calculate an attenuation budget of about 10 dB out of this not 13db.
No, you have it right below.
> However there is a term in the receiver table .
> ( I interpret max sensitivity here also as a minimum
> requirement, I don not
> hope that this means the sensitivity should not be better
> than this value,
> but this may be an editorial problem)
Maximum is more dBm, representing worst case for a receiver sensitivity, so
I think this one is the right way round. Please make a comment if any doubt
remains.
> Vertical eye closure penalty ** (max) 3.0 dB
> with a note
> **Vertical eye closure penalty is a test condition for
> measuring stressed
> receive sensitivity. It is not a required charac-teristic
> of the receiver.
> This note is a bit misleading for me, however I interpret
> this note in the
> way that when measuring stressed sensitivity there has to be
> used a signal
> that has 3 dB penalty, what means that for a signal that does
> not show this
> penalty ( as assumed at the transmitter in this
> consideration) we can add
> this to the sensitivity. Is this the ISI penalty you mention?
> In this case
> we really at the end coming out with 13 dB budget.
> Calculation would look like:
> _________________________________________________________
> transmitter OMA min -1.39 dBm
> _________________________________________________________
> receiver sensitivity (OMA) -11.40 dBm
> + receiver test signal penalty 3.0 dB
> _____________________________________________
> Total )penalty free signal) sensitivity in OMA
> -14.4 dBm
> __________________________________________________________
> attenuation budget
> 13.01 dB
>
> So can you confirm this understanding ?
Yes.
> If not would it be possible to set up a similar calculation
> like this and
> clarify.
>
> If this understanding is correct than we have 14.4 dBm sensitivity
> requirement in OMA and this for instance get it comparable to
> transponders
> you can by translates (being optimistic into average power
> sensitivity of :
> - 14.4 dBm OMA will give -17.4 dBm ideal ER sensitivity or
> -16 dBm (average
> power sensitivity) at ER of 8.2 dB as used in ITU. This is 2
> dB harder as
> ITU and represents the BOL typical value that you get for
> such components.
> For an interface spec we however require EOL worst case!
> For my understanding this is not realistic today and if done will be
> expensive.
Is it relevant to point out that SONET receiver sensitivities are
standardised for a "worst" Tx eye which has the same 3 dB penalty? Not sure
if you have already taken that into account.
> Regards Juergen Rahn
>
>
> > ----------
> > Von: Mike Dudek[SMTP:mdudek@xxxxxxxxxxxx]
> > Gesendet: Dienstag, 3. Juli 2001 03:02
> > An: Rahn, Juergen (Juergen)
> > Cc: stds-802-3-hssg-serialpmd@xxxxxxxx; 'Ron Miller'
> > Betreff: Re: AW: [802.3ae_Serial] Issue with 1500 Power
> >
> >
> > A further attempt to clarify this.
> > The 3dB difference is the ISI penalty that is imposed when
> performing the
> > stressed receiver sensitivity test which corresponds to the
> maximum value
> > of the
> > Transmitter and Dispersion Penalty of the Transmitter. If one has a
> > transmitter
> > that produces this amount of penalty then one has to
> increase the output
> > power
> > by 3dB. Hence the 13dB is attained.
> > Regards Mike
> >
> > "Rahn, Juergen (Juergen)" wrote:
> >
> > > Hi
> > > The difference between current defined sensitivity and
> what would be
> > > required (straightforward without any additional margin
> penalty....) is
> > 3
> > > dB, what means the attenuation budget would be 10 dB.
> > > Does this clarify?
> > > Regards Juergen
> > >
> > > > ----------
> > > > Von: Ron Miller[SMTP:rmiller@xxxxxxxxxxx]
> > > > Gesendet: Mittwoch, 27. Juni 2001 18:10
> > > > An: Rahn, Juergen (Juergen);
> stds-802-3-hssg-serialpmd@xxxxxxxx
> > > > Betreff: RE: [802.3ae_Serial] Issue with 1500 Power
> > > >
> > > >
> > > > juergen
> > > >
> > > > Please check your numbers below. Thanks
> > > >
> > > > Ron Miller
> > > >
> > > > -----Original Message-----
> > > > From: Rahn, Juergen (Juergen) [mailto:krahn@xxxxxxxxxx]
> > > > Sent: Wednesday, June 27, 2001 3:30 AM
> > > > To: stds-802-3-hssg-serialpmd@xxxxxxxx
> > > > Subject: AW: [802.3ae_Serial] Issue with 1500 Power
> > > >
> > > >
> > > >
> > > > Hi,
> > > > as discussed in the PMD call I understand there is a
> mismatch in the
> > > > values
> > > > defined for the 1550 case. The minimum transmitter OMA
> is -1.39dBm +
> > > > penalties. Link attenuation is set to 13 dB , so this
> would give a
> > > > sensitivity requirement of -14,39 dBm OMA ,. however
> the stressed
> > > > sensitivity (In OMA) is defined to be -11.4 dBm.
> > > >
> > > > so there are 10 dB
> > > > difference between those two values.
> > > >
> > > > LOOKS MORE LIKE ABUT 3 DB TO ME.
> > > >
> > > > The trade off that has been introduced
> > > > (that I do not like, but this is a different
> discussion) will shift
> > this
> > > > complete link power level. When comparing this with powers and
> > > > sensitivities
> > > > as defined in ITU the following appears: ITU defines 2
> dB path penalty
> > > > with
> > > > this OMA we would end at a minimum transmitter power average of
> > about -
> > > > 1
> > > > dBm which is in line to ITU. with 109 dB attenuation
> there is margin
> > in
> > > > the
> > > > ITU numbers, with 11 dB and ITU sensitivity (Which has
> been confirmed
> > by
> > > > measurements) we add up to 0. ( -14 dBm average power
> sensitivity and
> > 2 dB
> > > > penalty gives us the G.691 application). When simply taking this
> > > > transmitter
> > > > power and 13 dB attenuation we end up with 2 dB better
> sensitivity
> > > > requirement as currently experienced by measurements
> (worst case EOL).
> > > > This may start this conversation.
> > > > Regards Juergen
> > > >
> > > >
> >
>