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From: siegman@sierra.stanford.edu (Anthony E. Siegman)
Newsgroups: comp.dcom.telecom
Subject: Crosstalk Problem
Message-ID: 
Date: 11 Aug 89 01:03:27 GMT
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Reply-To: "Anthony E. Siegman" 
Organization: Stanford University
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Approved: telecom-request@vector.dallas.tx.us
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X-TELECOM-Digest: volume 9, issue 289, message 1 of 8

I have a crosstalk problem between my two residential lines, and would
appreciate suggestions for alleviating same.

Situation: Two residential lines coming into my house -- an old
installation, no conduit, the incoming service is just a lead-sheathed
bundle of 4 wires coming under the street and up out of the ground at
my outside utility box (can't add a 3rd line for my modem!).  Large
house, several additional rooms added to original structure.  All four
wires run all around the outside of the house (two twisted pairs of
weather proof wires under eaves), and also as a four-wire cable (NOT
two twisted pairs, at least I don't believe so, just 4 colored wires)
inside the walls in some of the more recent additions.  One line
serves the main part of the house (half a dozen phone sets), the other
serves a wing used as a rental unit (2 or 3 phones).

Problem: Big crosstalk between the two lines.  When I dial out on line
A, I have no problem in hearing, clearly if faintly, a concurrent
conversation on line B; and vice versa.  (But the person I'm calling
hears none of this, which seems odd?)  Audibility of crosstalk seems
to be quite different in different rooms, however, though the phones
are also different models, which might account for this.

Question:  How can I alleviate this?
I can go around and try to separate the wires under the eaves;
the cabling inside the walls is unfortunately inaccessible.  But would
it help to add some impedance, e.g., where lines A and B come out in
the same wall box but only A is used, would it help to load down B
with a termination of some sort, so the electrostatic coupling would
be looking into a lower impedance?

Any advice appreciated...