RE: PAM-5 at 5 Gbaud
Ed:
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:
>Richard:
>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 ps,
>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, 200
>ps, then those extra transitions will cause the PLL being out of
>synchronization with the receiving data, or excessive clock-jitter to induce
>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
>date.
you betcha!
--
>J M Wincn
>Cielo Communications, Inc.
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