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From: pkl@daisy.UUCP (Peter K. Lee)
Newsgroups: comp.dcom.modems
Subject: Re: TB+ Performance [Was: Trouble with TB Plus (Please Help!!)]
Message-ID: <3655@daisy.UUCP>
Date: 25 Sep 89 18:04:30 GMT
References: <132@clleth.UUCP> <235@tabbs.UUCP>
Reply-To: pkl@daisy.UUCP (Peter K. Lee)
Organization: Daisy/Cadnetix Corp., Mtn. View, CA
Lines: 28

I posted the original request on TB+ performance over trans-atlantic 
phone lines.  

I finally decided to call up Telebit technical support to get help.
I called up Telebit technical support to get help.  The guy was real
helpful in trying to decipher the S registers.  The few useful ones
are S70 and S72.  They contain the instantaneous send and receive line
speeds.  My S70/S72 registers are 8000+ which should give me at most
800 cps.  I tip to the other site, +++ back to my local modem and then 
dump S70/S72 to see what line speed I have.  I get this without setting
either S120 or J6S36 registers.  Setting these registers don't seem to
make much of a difference, so I may as well use the modems in a "standard"
configuration.

One other possibility is retraining.  When the noise level changes too
much, the modem will retrain itself.  You will see the RD/SD lights
went off for 8-10 seconds, it means that the modem is retraining.
That will kill the performance.  I don't see much retraining on mine,
but it does pauses for 2-3 seconds quite frequently.  Telebit says
that it is not retraining, but waiting for buffers to get flushed out.
My transfer speed also varies a lot.  The fastest that I've ever got
is 700+ cps for a 60K file.

Thanks to all those who have responded (by mail or followup).


-- 
-- Peter K. Lee (...!uunet!daisy!pkl), Daisy/Cadnetix Inc.