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RE: PAM-5 at 5 Gbaud


The presentation I am referring is page 8 (sorry not pager 7), of "10
Gb/sPMD Using PAM-5 Modulation" by Oscar in January.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: jmw [mailto:mwincn@xxxxxxxxxxxx]
Sent: Monday, February 28, 2000 4:43 PM
To: Edward Chang; rtaborek@xxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
Subject: RE: PAM-5 at 5 Gbaud


Perhaps i can help with this, Rich and i were at the same place when
the early MAS tutorials were presented:

At 02:20 PM 28-02-2000 -0500, Edward Chang wrote:
>The 5 GBaud, PAM-5 waveform at page 7 makes me very uncomfortable.  For
>example, the one in the middle has three transitions, of which the
>peak-to-peak amplitudes are 2250 unit(mv?), 1300 unit (mv?), and 1000
>unit(mv?) with estimated transition times, (0%-100%)65 ps, 60 ps, and 60
>respectively. For a five level coding, they seems to match with the +2, +1,
>0, -1, -2 level definition with equally spaced timing interval.
>If they are not part of the coding, but a ringing or some other noise, they
>will confuse the level and timing detecting circuits to cause undesirable
>results.  If it is supposed to have only one transition per a cell time,
>ps, then those extra transitions will cause the PLL being out of
>synchronization with the receiving data, or excessive clock-jitter to
>high BER.  With the near equal magnitude of amplitudes, and timing
>intervals, no way a ordinary filter can differentiate the needed transition
>from the unwanted transitions.

which presentation do you have?  i looked at the links posted earlier
("mastut.pdf"), but "page 7" in those that i saw was text, not wave forms.
is there some other one that i missed?

>One way or the other, these issues should be resolved before July decision

you betcha!
>J M Wincn
>Cielo Communications, Inc.
>325 Interlocken Pkwy, Bldg A
>Broomfield, CO 80021-3497
>Voice: 303-464-2264
>Cell:    408-394-5283