AW: [802.3ae_Serial] 1550 power budget
Hi,
There is one question I (and others) still have, and this is how to
interpret the 1550 nm interface power (OMA) levels and the attenuation. The
figures as written are not real transparent for me as the minimum
transmission signal and the receiver sensitivity together with the
attenuation do not add up to 0. can somebody help me there?
regards Juergen Rahn
> ----------
> Von: DAWE,PIERS (A-England,ex1)[SMTP:piers_dawe@xxxxxxxxxxx]
> Gesendet: Donnerstag, 21. Juni 2001 17:30
> An: '802.3ae Serial'
> Betreff: [802.3ae_Serial] From Serial PMD 19 June: 850nm eye mask,
> ORL spec, 1310serial ma x Tx power, ...
>
>
> Eye mask for 850 nm
> -------------------
> 850 nm proponents, please notice that the serial ad hoc is charged with
> producing a proposal for a 850-specific eye mask which would preserve the
> transmitter integrity requirements of the current draft standard but
> remove
> the need for rise time specification and measurement. This might be like
> a
> scaled OC-12 or 1GigE mask. Please email and join next week's call if
> interested.
>
> ORL
> ---
> We understand that ORL is total Optical Return Loss measured by
> disconnecting a transmitter from a link and measuring the link with a
> reflectometer. The far end receiver remains attached. Historically this
> has been a requirement of SONET but not of Ethernet. It seems that it
> guards against multiple reflection effects (parasitic etalons) in single
> mode links, where reflections that are individually within spec combine to
> create a problem.
>
> The following is a table (E&OE):
>
> | G.691 | 10GE |
> Discrete | 27 | 27 | 26 | 26 |
> Receiver | 14 | 24 | 12 | 26 |
> ORL | 14 | 24 | - | - |
> RIN test | - | - | 12 | 21 |
>
> If the ORL requirement is there to protect the transmitter from back
> reflection, 10G Ethernet could reasonably use the same numbers for ORL
> spec
> as it uses for RIN test. Input from the fibre and cabling community on
> the
> merit of an ORL spec at 1310 and/or 1550 nm is needed: please email or
> join
> next week's call!
>
> Receiver overload
> -----------------
> Suggested re-calculating the Tx max mean power from current likely Tx min.
> mean power + 5 dB for tolerances (keeping the 5 dB range we started with).
>
> How is stressed eye ISI value derived?
> --------------------------------------
> Thought to be calculated using a high receiver bandwidth rather than the
> usual 7.5 GHz, and with TP3 DCD (6 ps) rather than TP4 (8 ps). If this is
> right, to be recorded in "Notes" page of link model at next revision.
>
> Jitter
> ------
> 0.015 UI sigma_RJ thought to be too small. Obviously too much causes an
> error floor, but maybe 0.025 UI would be in the right ball park? But we
> don't know what would cause Tx RJ apart from RIN, because most oscillator
> phase noise is expected to be <4 MHz and tracked out by Rx PLL.
>
> We have accounted for some DJ in the model with the DCD factor. We are
> still thinking in the range 0.3 to 0.35 UI.
>
> Next meeting
> ------------
> Agenda items to include:
>
> 850 nm mask proposals
> ORL spec
> Receiver overload
> Refining jitter DJ and RJ spec numbers
>
> Usual coordinates:
>
> 15:15 GMT = 4:15 pm BST = 17:15 CET = 11:15 am EDT = 8:15 am PDT,
> Tuesday
> +1(816)650-0631 Access code 39209
>
> Piers
>