Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!apple!bionet!sdsu!crash!pnet01!scotto
From: scotto@pnet01.cts.com (Scott O'Connell)
Newsgroups: comp.dcom.modems
Subject: Re: Help - trailblazer not connecting in "fast" mode
Message-ID: <441@crash.cts.com>
Date: 26 Sep 89 23:16:08 GMT
Sender: root@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 32

> re: modem won't connect in fast mode but does at 2400 etc.

I had the same problem here in San Diego.  Worse yet it was while I was
evaluating v.32 modems.  I tried them on a couple o
f lines and still the
best I could do was 2400.  After many weeks of firmware changes, modem
paramaters and hours of frustration Telebit (one of the modems I was
evalMY}uating) set up a Spectrum Analyzer and found the problem.  It
was easy to spot because the PEP sends out a narrow pilot tone.  If there
is a loss on the line in that area the modem doesn't hear the other modem.
This was complicated by my V.32 testing which uses a much wider pilot tone.

Anyway, the phone company didn't understand the problem, said that the
line was within specs and left.  I found a line that worked, had them do
a comparison and they said "No difference".  Then they started swapping
pairs and discovered the problem followed a short strech of underground
cable about 5 miles from my office and 2 miles from the CO.  They swapped
that section for another pair and everything is working fine.

If it hadn't been for Telebit tech support I'd have been completely 
frustrated and settled for staying at 2400.  I'm glad they took the time
to help out.

If anyone is interested, I have prints of the spectrum analyzer results
that Telebit did.  I also would recommend talking to Lisa Masnaghetti at
Telebit and reminding her of my problem. 

-- Scott O'Connell

Scott O'Connell - Datagram Corp.   UUCP: {hplabs!hp-sdd sdcsvax nosc}...
3297 Sweetwater Springs Blvd #8          ...!crash!pnet01!scotto
San Diego, CA 92078-1477           ARPA: crash!pnet01!scotto@nosc.mil
800/235-5030                       INET: scotto@pnet01.cts.com