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Re: Re: PAM-5 at 1.25 Gbaud

In a message dated 2/5/00 9:37:41 AM, rtaborek@xxxxxxxxxxxxx wrote:

>I apologize and retract my statement about the PAM5 loss vs. PAM2 being 4.1 
>optical. The actual figure is much closer to 4.2 db. Assuming white Gaussian
>noise, for M-level PAM the multilevel optical power penalty is given by the
>following equation: Penalty = 10 log10((M-1)/sqrt(log2M)). For M = 2, 4, 5, 
>the penalty is 0, 3.3, 4.2, 6.1, ... dB.
>Optical link modeling is not my area of expertise. However, I have consulted
>with multiple optics experts to validate this result. You may be well served 
>do the same. 


I think you are wrong and I explained to you in great detail in a private 
email a week ago why I consider that the PAM-5 signal power penalty is 6 dB 
optical and 12 dB electrical. I discussed this issue with David Cunningham 
more than half a year ago and with Del Hanson a few days ago, and they agree 
with this assessment. In fact, David was the first to point out what these 
penalties are.

I would suggest you that in your next presentation in March in the 10 GbE 
Task Force meeting you explain to everyone in great detail the right way to 
calculate the optical and electrical power penalties of PAM-5 modulation and 
the correct numbers for these penalties.

You know that I have some sympathy towards PAM-5 ... You already have my 
emotional support to your position.

Jaime E. Kardontchik
Micro Linear
San Jose, CA 95131