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During today’s XLAUI/CAUI Ad Hoc
call I picked up some action items to E-mail out some items. Here
are these items. 1 There
was significant debate as to whether the XLAUI/CAUI IEEE specification should
be just for chip to chip, or whether additional test point specifications
should be included for host/module. Ie whether the host/module
specs for the retimed interface are included in 802.3 or left for development by
other groups such as MSA’s or SFF committee. Jeff volunteered to
ask CFP members their views, however I think it is an appropriate topic for the
complete group. (FYI The non-retimed PPI host/module interface
specs are being developed in IEEE in Clause 86). 2 Detailed
specification discussion. Proposals have been made to define rise/fall
times and De-emphasis. To define rise/fall times in a
reproducible manner, particularly for waveforms with de-emphasis the 0 and 100%
levels have to be defined in an un-ambiguous manner. Clause 86 is
using the stable levels on the square wave pattern (the same levels as used for
OMA/VMA measurement). I think this is the best method, as I think
this probably best predicts system performance. Alternatives
are however the peak levels as defined for De-emphasis (see later), or the
average value of the center 20% of the eye diagram (as used to define zero and
one values in the eye diagram). A proposal has been made to define
De-emphasis as the ratio between peak-peak values and the stable one/zero
levels. Again un-ambiguous definitions are required for peak-peak and
stable one/zero. The proposal suggested that the square wave
pattern is used. The stable one/zero levels could be defined
identically to VMA (average value over center 20% of the one and zero levels of
the square wave). Other definitions are possible, but I see no
advantage in creating a different definition. For the peak values
it was suggested that it should be the value at 0.5UI, however on the call zero
time had not been defined. One definition that I think is reasonable is
the zero crossing time of the square wave. Another definition for the
zero time would be the zero crossing time of the 101010 pattern. (however
this has the disadvantage of requiring a 101010 test pattern that is not
presently defined.). Yet another definition could be to use
the mean crossing point as used to align an eye mask. There are
also other possible definitions that do not require establishing an exact zero
time reference. Peak could be defined as the peak value at any time
within an averaged square wave. Peak-Peak could be defined as the
amplitude of a 101010 averaged signal (again however this has the disadvantage
of requiring the 101010 test pattern). Personally I think the peak
value at any time within the averaged square wave is probably the easiest
definition and recommend it’s use unless there are reasons not to do
this. My second choice would be 0.5UI after the zero crossing of
the square wave. Mike Dudek PMTS Standards & Technology JDS Uniphase CO 80027 Tel 303 530 3189 x7533. mike.dudek@xxxxxxxx From: Dear 802.3ba Colleagues, I'd like to schedule the next meeting for the XLAUI / CAUI Ad Hoc as
follows: Friday December 19th 8:30am - 10:30am Dial-in Number (Canada & USA) :1 877 234
4610 Participant Conference Access code: 4405734 # (see below for additional
phone numbers) Presentations should focus on technical details / values related to the
nAUI specification. In particular, I would like to focus on the channel
specification & de-emphasis proposals. Anyone wishing to present, please follow the guidelines described on
the Procedure for Presenters web page: http://www.ieee802.org/3/hssg/public/presentproc.html If you are planning to participate please take a moment to read the
IEEE patent policy available here:
http://standards.ieee.org/board/pat/pat-slideset.ppt.
* Participant Conference
Access code: 4405734 # * Dial-in Number:416 883
8981 * Dial-in Number:1 877 234
4610 Best Regards, Ryan Market Manager Analog & Mixed-Signal Products Gennum Corporation Phone: 905 632 2999 x 1610 |