Re: [10GBT] More on the PAM12 emissions
Are you proposing that we drop power backoff for short cables ? I believe
both proposals on the table recognize the importance of backing off the Tx
power in short reach applications. Also, as Dr. Ungerboeck pointed out
quite well in ungerboeck_1_0704.pdf, there is really no need to "zero out"
the THP coefficients.
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf
Of sailesh rao
Sent: Monday, July 26, 2004 11:18 AM
Subject: [10GBT] More on the PAM12 emissions
I'm attaching the corrected glenn.m code with the proper repetition rate
(4224 symbols). For those of you who don't have access to matlab, I'm also
attaching the output of this code with 4224 (5us) and 422224 (0.5ms) as pdf
plots. This illustrates the actual energy buildup we can expect in the PAM12
framing scheme, as depicted on slide 22 of powell_1_0704.pdf.
Another issue with the PAM12 proposal is that the bit-to-symbol mapping on
slide 24 of powell_1_0704.pdf will cause a 0.47dB increase in the transmit
PSD power when the THP coefficients are zero'ed out (e.g., at short line
lengths). In contrast, in the PAM8 proposal, if the THP coefficients are
zero, the transmit PSD power will decrease by 0.03dB.
Therefore, I would like to officially raise the PAM12 emissions penalty to
1.3dB from the 0.8dB I had been quoting. In this case, the total EMI penalty
of PAM12 is between 4.5dB and 5.1dB over the existing cabling
infrastructure. It is between 3.1dB and 4.5dB for new cabling.
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