siegman@sierra.stanford.edu (Anthony E. Siegman) (08/11/89)
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...
dave@uunet.uu.net (Dave Levenson) (08/13/89)
In article <telecom-v09i0289m01@vector.dallas.tx.us>, siegman@sierra.stanford. edu (Anthony E. Siegman) writes: > 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!). ... > 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) The problem is that the two lines run parallel in a non-twisted cable. Twisted pairs are used to reduce electromagnetic coupling between the circuits. Four-wire station quad is not intended for use in carying two lines, though it's often done without problems for short runs. Perhaps you can use the existing quad as a drag line to help pull through the twisted pair that will replace it! -- Dave Levenson Voice: (201) 647 0900 Westmark, Inc. Internet: dave@westmark.uu.net Warren, NJ, USA UUCP: {uunet | rutgers | att}!westmark!dave [The Man in the Mooney] AT&T Mail: !westmark!dave