Any way to cut telephone crosstalk?

[petrus bitbyter]

"Don Taylor" <dont@agora.rdrop.com> schreef in bericht
news:7dudnWPkMsozWZTfRVn-1g@scnresearch.com...

"petrus bitbyter" <p.kralt@reducespamforchello.nl> writes:
"Don Taylor" <dont@agora.rdrop.com> schreef in bericht
news:xf2dnQ2gQqbRxJXfRVn-tQ@scnresearch.com...
Wall jack, 4 foot cord, internal modem, 4 foot cord, telephone.

If it is a "newer" phone, the 6 ounce plastic pushbutton kind,
I pick up the handset, dial 1 and listen there is LOUD crosstalk.

If I unplug that and go dig out my ancient old ITT bell rotary 3 pound
desk phone from decades ago and try the same there is NO crosstalk.

Crosstalk is about unwanted signal transfer between two (telephone)lines,
so
two sets of wires. So what other line do you hear after dialing that 1?
Can't imagine crosstalk in the last 4 foot cord where you are the only
user.
So what do you hear? Yourself? Then most likely the antilocalcircuit in
your
phone is broken. The old machines used transformers that are almost
undestructable but the new electronic circuits are more sensitive. Other
possibilties are wrong wiring and bad contacts.

Conversation from somewhere else, that was why I called it crosstalk
rather than echo. And as I said, identical results if I take the pair
of phones outside to the terminal block and repeat the experiment there
with no inside wiring, no modem, no computer.

Do you achieve the same result if you keep the modemcard out? Then the
above
stands. If not, you have to look for more precisely for bad contacts
between
phone and modem. That RJxx jackets sometimes get lame contacts. The plug
also can be damaged. I met both cases several times.

I've looked at jack and plug, both appear to be clean, not corroded,
not badly bent, pretty good looking to me.

If you really hear another line, it's almost sure the impedance matching
between line and phone is very bad. Most likely some circuit in the phone
became defective although wrong wiring and bad contacts are also a
possible
cause (as always).

By eliminating all the inside wiring and the computer and everything
to the outside jack, and the problem persists, it seems like we are
getting closer to the problem. But I'm still not seeing any solution
other than going back to the 1970's Bell rotary desk phone, yet.

thanks

Well,

That third party conversation is picked up somewhere along the line. Most
likely on a place the lines are running parallel over some distance. Your
line looks like an antenna that picks up the radiation from the other line.
Most likely the cause is lack of correct termination on the phones side if
there is some termination at all. Maybe the internal state of the phone
changes after pressing the 1, maybe the exchange makes some connection when
you do. Nevertheless, your phone is either defective or suffers from a
design flaw. You can open it and look for broken contacts or bad solder
joints but with low chance for succes. You could try to put a resistor in
the phone to correct termination but I can't be sure to tell where and how
even if I have the phone in my own hands. (If you knew you should not have
to put the question in the first place.) You can buy or borrow another phone
just to check your findings. Think you have to buy another one anyway if you
want to get rid of that crosstalk. They are not that expensive after all.

petrus bitbyter

 

[Don Taylor]

Allan Adler <ara@nestle.csail.mit.edu> writes:

How do you know it is cross talk and not some other signal,
such as a radio station's talk show?

From the conversation going on it is going to be one personal
talk show!

A few years ago, I had a phone which seemed also to pick up a radio
station. It was so bad that when I tried to use it to dial up my ISP,
the computer said it couldn't find the dial tone. The problem was solved
by using a filter from Radio Shack. I only used the filter with the computer,
so I don't know whether it would have improved the sound quality if I had
used it with the phone.

The elderly friend of mine who kept telling me he had this problem,
and I kept dismissing it as just one more example of elderly
crankiness.. until I happened to drive the 40 miles to go see him,
tried to make a call and the conversation on the phone line was
louder than usual phone conversations! And that was after dialing
a single digit to just silence the dial tone. And his hearing/
tinnitus is worse than mine. No wonder he had complained.

Usually I consider it an act of desperation to buy anything from Radio Shack,
and it was certainly one in this case, but they actually had a solution when
no one else did.

Now a filter sounds like a possibility. Have you got more details
about what I'm supposed to look for? The last time I went in looking
for parts at Radio Shack the minute they realized I wasn't going
to make them a cell phone contract commission they went back to
talking among themselves.

And, I have an honest suggestion, for the folks who discussed
"certified" phones. Choose a phone supplier, you get to pick the
one that you think has the best chance. The next time you might
be there, ask the salesman if the phone is really "certified" and
see if they can tell you something to make you believe they actually
know what they are talking about. To be honest I would be REALLY
surprised if they know what you are talking about and even more
surprised if they can actually show anything that confirms this.
Please report back, I would love to hear what the outcome was.

Someone suggested the phone company would sell "certified" phones
and I should buy one of those. I honestly wouldn't think that Qwest
or Verizon even sells non-cell phones any more, I'll call them up
and tell them I want to buy one of the certified ones and see what
happens. But before I started this I did call and they offered to
come check the inside wiring ($50 plus hourly I think)

I worked for Tek decades ago and we had our own EMI cert lab, but
I never did any cert work. I wonder if they dumped that long ago,
along with the 80% of the workforce.

Thanks

 

[Ken Taylor]

"Ken Taylor" <ken123@xtra.co.nz> wrote in message
news:36vf2tF57dfgdU1@individual.net...

"Don Taylor" <dont@agora.rdrop.com> wrote in message
news:y7mdneeqQPFgI5TfRVn-hw@scnresearch.com...
"Ken Taylor" <ken123@xtra.co.nz> writes:
"Don Taylor" <dont@agora.rdrop.com> wrote in message
news:xf2dnQ2gQqbRxJXfRVn-tQ@scnresearch.com...
Wall jack, 4 foot cord, internal modem, 4 foot cord, telephone.

If it is a "newer" phone, the 6 ounce plastic pushbutton kind,
I pick up the handset, dial 1 and listen there is LOUD crosstalk.

If I unplug that and go dig out my ancient old ITT bell rotary 3 pound
desk phone from decades ago and try the same there is NO crosstalk.
...
When you say 'cross-talk', is it other people's conversations or echoes?

Conversations

Does it happen with handset plugged straight into the wall jack?

Yes, and even when I try it outside at the terminal block.

Are there any other extension sockets on your line in your house?

No

Okay, your problem is in the telco wiring, most likely a high-resistance
joint (or water in a cable pit somewhere). Call them and get it fixed.

Ken


Incidentally, FWIW, if you tell the telco that you hear other conversations

they generally react faster than if you just say it's noisy or your modem
doesn't train up nicely. Privacy, and all that.

Cheers.

Ken

 

[Allan Adler]

dont@agora.rdrop.com (Don Taylor) writes:

Allan Adler <ara@nestle.csail.mit.edu> writes:
Usually I consider it an act of desperation to buy anything from Radio Shack,
and it was certainly one in this case, but they actually had a solution when
no one else did.

Now a filter sounds like a possibility. Have you got more details
about what I'm supposed to look for?

I don't think I can describe it adequately without running a serious
risk of misleading you. It's a few inches long with phone cables coming
out of both ends, as I recall. I haven't needed it in a few years, so it
isn't too fresh in my mind.

I suggest you just call them up and describe the problem and ask if they
have any ideas for a phone filter. They'll probably want to know whether
it is a regular phone line or a DSL or whatever. I think they do call it
a phone filter. I've never had trouble getting them to answer questions
over the phone. It just cost a few bucks.
--
Ignorantly,
Allan Adler <ara@zurich.csail.mit.edu>
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

 

When you say 'cross-talk', is it other people's conversations or
echoes?

Conversations

Does it happen with handset plugged straight into the wall jack?

Yes, and even when I try it outside at the terminal block.

Since it seems like other conversations(and not a radio station or CB)
it looks like a exterior (telephone company ) problem. Using the old
phone would change the load on the line. I had this problem on my phone
lines every time it would rain. I thought it was only me until I heard
the other party mention the crosstalk and the 2nd person said "Oh just
ignore them, they're screwing up my line!" and I said "Uhh actually
it's you screwing up mine." Anyway the phone company finally fixed the
problem.
Richard