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From: dya@unc-c.UUCP
Newsgroups: net.dcom
Subject: UDS 9600 bps dial-through modems
Message-ID: <1279@unc-c.UUCP>
Date: Fri, 23-Mar-84 16:03:17 EST
Article-I.D.: unc-c.1279
Posted: Fri Mar 23 16:03:17 1984
Date-Received: Sun, 25-Mar-84 10:25:48 EST
Lines: 37


<Here's the beef....>

     Well, it seems that the problem with the UDS modems in Orchard Park
was that there seems to be some extremely long time constant AGC/Compandor/
Noise Gate/something with a delta-G function... that was chopping off the
front of the training burst. Thus, the adaptive equaliser inside was getting
the wrong idea.

     If we pulsed the lines with a short burst, then went back and repeated
it (before the AGC/whatever returned to a quiescent state) with sending real
data, the constellation from the modem is darn nearly PERFECT over these
extremely long loops.

     NOW the question ois:

     1) On local loops and ESS 2B, what kind of funny amplifiers are there
        such as noise gates/AGC/analog companders with extremely slow attack
        times ?
        ( This effect wasn't noticed on long distance loop through UDS's
          own loop-through facilities )

     2) How do we get RID of them ?

     3) It doesn't seem to be in every ESS 2B, as they do work fine here
        in Charlotte ESS office ( 535, 568 ), just Buffalo <Orchard Park> 662-
        and Hamburg, NY..

     Please !!. We aren't going to lose your job for you, we just want these
darn modems to work everywhere ( after all, 9600 bps Compuserve isn't bad ?)
for a research project. They * HAVE * to work in New York, and they seem to
work anywhere else. No one at New York Tel has a definitive answer, so we have
ESS 2B is either all digital or analog within the C.O. ).

David "they're companders, but it sure ain't DBX" Anthony

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