Velocity factor telephone cable

Hello guys...

Can anyone give me the correct name to look for? I'm trying to find the
specs for those last-100m-or-so outdoor phone cables, which are flat,
single pair, but with a center support wire.

They have a very tough (black) plastic (very difficult to make knots).

I'm particularly interested in velocity factor (my ADSL is failing, and
the phone techs can't seem to locate the fault - or they don't want to).

I seem to miss the correct terms to guide google. It doesn't help that
phone cables are used for everything nowadays.

John
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[hermanaa-2]

On Fri, 2009-11-06 at 19:05 -0300, John Coppens wrote:

> Hello guys...
>
> Can anyone give me the correct name to look for? I'm trying to find the
> specs for those last-100m-or-so outdoor phone cables, which are flat,
> single pair, but with a center support wire.
>
> They have a very tough (black) plastic (very difficult to make knots).
>
> I'm particularly interested in velocity factor (my ADSL is failing, and
> the phone techs can't seem to locate the fault - or they don't want to).
>
> I seem to miss the correct terms to guide google. It doesn't help that
> phone cables are used for everything nowadays.
>
> John

John .... I dont know much except that the tel.line is highly
UN-critical for ADSL.
When my tel.line was broken (one conductor open), ADSL was still
working. Against ground apparently.

My line is 2-conductor (no center-support wire) asfar the telco goes.
The last 200M (my responsibility) is flat cable (lampshade-wire) twisted
around GI (Galvanized Iron) wire for strength. I replace it every 4
years about.

Herman in Philippines.


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[Lee Jones]

> Can anyone give me the correct name to look for? I'm trying to
> find the specs for those last-100m-or-so outdoor phone cables,
> which are flat, single pair, but with a center support wire.

> They have a very tough (black) plastic (very difficult to make knots).

Assuming you are talking about overhead phone service --

I've always known them as "drop cable" (since they provide the
drop from the telephone pole to the premises).  It comes in both
1 pair and 2 pair versions with or without the carrier wire.
The conductors, particularly in the version without a carrier
wire, are steel.  About 20-22 gauge.

I tried "steel wire drop cable" in Google and got a number of
hits that seemed promising.

If underground service, I believe standard UTP is used.  It used
to be category 3 for phone service but it is likely to be cat 5
now (just due to economy of scale).


> I'm particularly interested in velocity factor (my ADSL is failing,
> and the phone techs can't seem to locate the fault - or they don't
> want to).

Could be both!  (Incompetant & lazy are not mutually exclusive.)

                                                Lee Jones

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[Richard Prosser]

Lee,

We call them drop cables but you may have a diiferet phrase in you area.

The velocity factor will depend on the type of cable it is. Your
description is not quite enough for me to identify it as we use
different cable types here in NZ.

If it's an overhead cable le with a soft plastic insulation (expanded
Pe) the velocity factor could be as high as 0.8. If it's harder
plastic - (expanded PP) the factor is likely to be a bit lower - 0.73
or so. If the cable is buried type Filled with grease it could be
lower still. If solid plastic insulation it is likely to be 0,67 or
thereabouts.

In the unlikey event it is PVC insulation, the velocity factor will be
lower again and also frequency dependent.

If you can get a sample of the cable to measure, then the capacitance
& velocity factor are closely related. Let me know the value & I'll
try & remember the equation..

RP

2009/11/7 Lee Jones <lee@...>:

>> Can anyone give me the correct name to look for? I'm trying to
>> find the specs for those last-100m-or-so outdoor phone cables,
>> which are flat, single pair, but with a center support wire.
>
>> They have a very tough (black) plastic (very difficult to make knots).
>
> Assuming you are talking about overhead phone service --
>
> I've always known them as "drop cable" (since they provide the
> drop from the telephone pole to the premises).  It comes in both
> 1 pair and 2 pair versions with or without the carrier wire.
> The conductors, particularly in the version without a carrier
> wire, are steel.  About 20-22 gauge.
>
> I tried "steel wire drop cable" in Google and got a number of
> hits that seemed promising.
>
> If underground service, I believe standard UTP is used.  It used
> to be category 3 for phone service but it is likely to be cat 5
> now (just due to economy of scale).
>
>
>> I'm particularly interested in velocity factor (my ADSL is failing,
>> and the phone techs can't seem to locate the fault - or they don't
>> want to).
>
> Could be both!  (Incompetant & lazy are not mutually exclusive.)
>
>                                                Lee Jones
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>

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[Enrico Schuerrer]

John Coppens schrieb:

> Hello guys...
>
> Can anyone give me the correct name to look for? I'm trying to find the
> specs for those last-100m-or-so outdoor phone cables, which are flat,
> single pair, but with a center support wire.
>
> They have a very tough (black) plastic (very difficult to make knots).
>
> I'm particularly interested in velocity factor (my ADSL is failing, and
> the phone techs can't seem to locate the fault - or they don't want to).
>
> I seem to miss the correct terms to guide google. It doesn't help that
> phone cables are used for everything nowadays.
>
> John

The velocity factor depends on the used material - if it is
PVC--insulated material, the speed is around 176 m/µs, if it is PE the
speed is around 204 m/µs. This speed depends mostly on the capacity of
the wires against each other and ground and the Epsilon-r of the used
isolating material.

In Europe the Telcos use mostly filled cables (isoparaffine) with PE
foam coated copper, this speed is around 196 m/µs.

Regards

Enrico

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[cdenk]

I'm not terribly technical in this thread, but:
I'm about 2.2 miles from the central office equipment, our speed is
high, neighbor 1/4 mile further down the road only can get low speed
DSL. About every 2 years the central office equipment for our line goes
out. Takes a call to tech. support to issue a work order, and by 11:00
A.M. the next morning we are back online. Has the technician changed out
your central office module? Has he tested for signal at the pole, or
interchange box, or some other places along the distance to the central
office. I tend to think unless the cable is damaged, the cable isn't the
issue. Our circuit starting at the central office is 2.2 miles of many
pair cable hanging on poles, 100' of 2 pair drop cable to the pole in
front our house, 100', and 50' multi pair underground direct burial
cable in plastic conduit, 15' cat-5, 3' cat-5. All these pieces of cable
are terminated, mostly with stud and nut, and some RJ-45. With this mix
of cable, and it works fine, can't be that fussy. :)
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[kenn]

Bugzilla from [e-mail] wrote:

my ADSL is failing, and
the phone techs can't seem to locate the fault - or they don't want to).

If the telephone on that line is working good (clean, loud, no crackles or noise), then the line should usually be OK for ASDL as well. In North America, there's usually a phone jack right on the terminating device where the phone line enters the house. This is called the demarcation point. If the phone tech can disconnect your house wiring and get a proper signal at the demarcation point, then the fault is in the house - a bad phone or a wiring fault, and it's usually fixed at your expense. You should try putting your DSL modem right at this entrance point, disconnect the rest of the house phone wiring if you can, and see if the ADSL works there.

In about 6 years, the only time my ADSL failed, the phone line was still clean and good. It took me a week to reach someone smart enough to check the ADSL modems at the CO, where they found that one side of the connection to their DSL modem had opened up.

[cdenk]

That's what I was saying, the CO DSL equipment fails about every 2
years, but the techies seem to be well aware, and it's fixed the next
morning in about the time it takes to send the person driving to the CO.
And yes the interchange box has an RJ-11, just unplub, and plug your
modem in. If you don't have an interchange box outside your hose request
the telephone company to install one. Most likely they will be very
happy to.

kenn wrote:

>
> Bugzilla from john@... wrote:
>  
>> my ADSL is failing, and
>> the phone techs can't seem to locate the fault - or they don't want to).
>>
>>    
>
> If the telephone on that line is working good (clean, loud, no crackles or
> noise), then the line should usually be OK for ASDL as well. In North
> America, there's usually a phone jack right on the terminating device where
> the phone line enters the house. This is called the demarcation point. If
> the phone tech can disconnect your house wiring and get a proper signal at
> the demarcation point, then the fault is in the house - a bad phone or a
> wiring fault, and it's usually fixed at your expense. You should try putting
> your DSL modem right at this entrance point, disconnect the rest of the
> house phone wiring if you can, and see if the ADSL works there.
>
> In about 6 years, the only time my ADSL failed, the phone line was still
> clean and good. It took me a week to reach someone smart enough to check the
> ADSL modems at the CO, where they found that one side of the connection to
> their DSL modem had opened up.
>
>  

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