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From: enger@SEKA.SCC.COM (Robert M. Enger)
Newsgroups: comp.sys.proteon
Subject: Re:  4-into-6 coding, and the "clasic" pronet-80 problem
Message-ID: <9003200023.AA04178@seka.scc.com>
Date: 20 Mar 90 00:23:28 GMT
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Organization: The Internet
Lines: 33

Cliff:

Thanks for the info.  Yes, it is helpfull.

Do you have the mapping table for the 4-> coding used by proteon?
Can I get a copy?
Do any of the allowed codes result in strings of four zeros, four ones?

Are any of the pronet-80 interface statistics of any real use in
locating the culprit?  Given the frequency and magnitude of the
problem, I would hope that some parameter they report is usefull.

I do not have any fiber equipment here to blame the problem on.
I have 8 P4200s, sitting in the same room, connected to a 
ganged wire-center.  Intuition would lead one to believe
that this would be a "piece of cake" installation.  
Since all boxes are subject to the same environmental conditions
all the clocks and chips should suffer temperature drift in the
same direction, if not the same amount.  The AC power supplied
to all the units should be closely matched.  Even the pronet-80
cables are short, so capacitive effects should be small.

I guess I should express an overdue thanks.  We have been using
the special ping program from jade for quite some time.
That is how we have been poking at the ring!

>From you description of the problem, is it correct to sum up that
the problem is not one of wave-form deformation, but rather
receiver time-base instability?  (ie, receiver can't be trusted
to sample signal near the middle of the bit-time?)

thanks,
Bob