UK Phone line question...

[Mike Coon]

In article <ridodv$rnl$1@dont-email.me>, kraken.sankey@gmail.com says...

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

It used to be the case that when your phone rang the exchange supplied
enough power to operate a loud bell. I don\'t know the specification. I
presume they are still capable of doing that even though most phones are
locally powered now and use efficient sounders. So if you can find an
old mechanical phone and ring your own number maybe that would put
enough current through your cable to detect with a coil and audio
amplifier even if it\'s a twisted pair...

Mike.

 

[Jasen Betts]

On 2020-08-29, Mike Coon <gravity@mjcoon.plus.com> wrote:

In article <ridodv$rnl$1@dont-email.me>, kraken.sankey@gmail.com says...

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

It used to be the case that when your phone rang the exchange supplied
enough power to operate a loud bell. I don\'t know the specification. I
presume they are still capable of doing that even though most phones are
locally powered now and use efficient sounders. So if you can find an
old mechanical phone and ring your own number maybe that would put
enough current through your cable to detect with a coil and audio
amplifier even if it\'s a twisted pair...

Mike.

The POTS ring frequency is 16-2/3 Hz (in UK), so it may be hard to detect.

Downstream ADSL traffic is upto 1104 Khz so you may be able to detect
that with an AM radio. (just leave you-tube on auto-play or something
like that.)


--
Jasen.

 

[server]

On Saturday, 29 August 2020 16:35:04 UTC+1, TTman wrote:

On 29/08/2020 15:54, jlarkin@highlandsniptechnology.com wrote:
On Sat, 29 Aug 2020 15:23:59 +0100, TTman <kraken.sankey@gmail.com
wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

If it\'s a coax, you can force an audio-frequency current into the
shield (it\'s probably grounded somewhere out there) and snoop for the
magnetic field. I\'ve found wires inside walls, by listening for the 60
Hz field when there was current in the wires.

It would probably work with an unshielded pair, too.



UK uses 2 twisted pairs( 1 is spare for residential use) in plastic
outer. No shield.

Except when it is shielded. I have an underground BT phone line (with
VDSL internet) which uses steel wire armoured twisted pair cable.
Two pairs I think. Such cable is very robust. It is also possible to
attach a signal generator to the shield which might help with tracing.

John

 

[Les Cargill]

TTman wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

Inject a signal in the AM radio band and use a small AM radio like you\'d
use a metal detector. Dunno if it\'d be better to use the shield, fly the
shield from ground or what.

--
Les Cargill

 

[TTman]

If you are anywhere near Bath, get in touch with me (contact details on
website), I may be able to help.

Isle of wight.


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[TTman]

It used to be the case that when your phone rang the exchange supplied
enough power to operate a loud bell. I don\'t know the specification. I
presume they are still capable of doing that even though most phones are
locally powered now and use efficient sounders. So if you can find an
old mechanical phone and ring your own number maybe that would put
enough current through your cable to detect with a coil and audio
amplifier even if it\'s a twisted pair...

Mike.

Worth a try... with my metal detector with the phone ringing...

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[Adrian Tuddenham]

TTman <kraken.sankey@gmail.com> wrote:

If you are anywhere near Bath, get in touch with me (contact details on
website), I may be able to help.



Isle of wight.

Pity, I have the kit you need but the IOW is a long way to go.

You won\'t pick up anything from loop currents in the \'phone line, you
need to inject longitudinal current in all the conductors in the same
direction (\'common mode\'). Then connect a multi-turn coil to a
sensitive amplifier and listen on headphones (a loudspeaker might create
a strong enough field to give feedback). Frequencies around 1 to 2 Kc/s
generally give the best results and pulsing them can help to make them
more audible if there is a lot of noise.

The coil could be something like the mains primary of an old transformer
with the laminations removed or the energising coil off an old
loudspeaker. If you can fix it on the end of a broom handle and swing
it to-and-fro like a pendulum, you will hear a sharp null in the signal
when it is pointing directly at the cable.

Make sure your signal earth return path doesn\'t run anywhere near the
cable you are trying to trace or you may find you are following the
wrong one. Ideally you should hammer in an earth stake some distance in
the opposite direction from the cable run and make your earth connection
to that.


--
~ Adrian Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[Michael_A_Terrell]

TTman wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

I was asked to locate a break in buried wires to an electric
security gate on a 1000+ acre nursery. I used a modulated signal in the
AM Broadcast band, and a transistor radio to follow the signal. One of
their Gardners had cut it with a shovel in three places. I found one,
repaired it and the gate still didn\'t work. I found the other two breaks
and repaired them, before it worked. The intercom part hadn\'t worked in
years. I repaired that as well. I was tere to repair a C-band TV system.
Before I l left that day I had also repaired a front end loader\'s
damaged wiring harness. I always hated multiple jobs on one ticket!


--
Never piss off an Engineer!

They don\'t get mad.

They don\'t get even.

They go for over unity! ;-)

 

[Adrian Tuddenham]

Adrian Tuddenham <adrian@poppyrecords.invalid.invalid> wrote:

TTman <kraken.sankey@gmail.com> wrote:


If you are anywhere near Bath, get in touch with me (contact details on
website), I may be able to help.



Isle of wight.

Pity, I have the kit you need but the IOW is a long way to go.

You won\'t pick up anything from loop currents in the \'phone line, you
need to inject longitudinal current in all the conductors in the same
direction (\'common mode\'). Then connect a multi-turn coil to a
sensitive amplifier and listen on headphones (a loudspeaker might create
a strong enough field to give feedback). Frequencies around 1 to 2 Kc/s
generally give the best results and pulsing them can help to make them
more audible if there is a lot of noise.

The coil could be something like the mains primary of an old transformer
with the laminations removed or the energising coil off an old
loudspeaker. If you can fix it on the end of a broom handle and swing
it to-and-fro like a pendulum, you will hear a sharp null in the signal
when it is pointing directly at the cable.

Make sure your signal earth return path doesn\'t run anywhere near the
cable you are trying to trace or you may find you are following the
wrong one. Ideally you should hammer in an earth stake some distance in
the opposite direction from the cable run and make your earth connection
to that.

Just to follow this up, I\'ve been making some measurements:

For the detector coil I used 2,000 turns of wire on a small plastic reel
that had been used for solder, the winding space was 2\" long, 2\" outside
diameter on a 1\" dia core. I screened it against unwanted capacitive
pickup with cooking foil, overlapped but insulated to avoid a shorted
turn.

The amplifier was a NE5534 arranged for an input impedance of 47K,
followed by a TL072; full gain was about 94 dbU into a pair of 30-ohm
stereo headphones with the capsules wired in series mono and driven in
\'bridge\'. I have uploaded the circuit to:
http://www.poppyrecords.co.uk/other/DualImpedanceAmplifier.gif


A piece of wire lying on the surface of the lawn, carrying 1mA rms
sinewave at 1.5 Kc/s was very easily detected at a distance of well over
a metre. As this is magnetic induction, there will be very little
attenuation from passing through the soil, so you could expect similar
results with a buried cable.


--
~ Adrian Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[David Lesher]

TTman <kraken.sankey@gmail.com> writes:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?

Call 811 first... oops that must be 118 Over There.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that\'s close..........................
Unless the host (that isn\'t close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

In the US, the locator companies typically inject 38KHz from a conductor to
ground, and use a loop antenna and receiver to mark the route.


--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that\'s close..........................
Unless the host (that isn\'t close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Martin Brown]

On 29/08/2020 17:57, jlarkin@highlandsniptechnology.com wrote:

On Sat, 29 Aug 2020 16:34:57 +0100, TTman <kraken.sankey@gmail.com
wrote:

On 29/08/2020 15:54, jlarkin@highlandsniptechnology.com wrote:
On Sat, 29 Aug 2020 15:23:59 +0100, TTman <kraken.sankey@gmail.com
wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

If it\'s a coax, you can force an audio-frequency current into the
shield (it\'s probably grounded somewhere out there) and snoop for the
magnetic field. I\'ve found wires inside walls, by listening for the 60
Hz field when there was current in the wires.

It would probably work with an unshielded pair, too.

UK uses 2 twisted pairs( 1 is spare for residential use) in plastic
outer. No shield.

What sorts of data rates do you get over an unshielded buried twisted
pair?

ADSL is good for up to 8Mbps down and 448kbps up back to the exchange.
ADSL2+ (current offering) will do 22M/1M on a good day but not for me.

Speed is intimately related to line attenuation and distance. I get
about 5Mbps/1Mbps on a 5km 1960\'s copper line back to the exchange. Less
if it is windy or the beck is in spate and the cable ducts flooded with
water. Combination of overhead lines and buried so worst of both worlds.

Fibre to cabinet will get you closer to 80Mbps down 20Mbps up. That
typically leaves only the last 500m on copper twisted pairs.

The graph at the bottom of this page shows the distribution of speeds
and technologies in the UK at present (well in 2014).

https://kitz.co.uk/adsl/fibre-optic-broadband.htm

FTTrN sank without trace some while ago. Some diurnal variation in SNR
as continental radio broadcasts interfere a bit after sunset.

I\'m getting 120/40 Mbits at home from the cable TV provider, which is
shockingly better than what we got over old soggy twisted pairs from
AT&T.

Cable TV is only available in cities.
My brother in law gets 350M down/35M up on that with a cable TV feed.

--
Regards,
Martin Brown

 

[John Larkin]

On Mon, 31 Aug 2020 20:17:11 +0100, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 29/08/2020 17:57, jlarkin@highlandsniptechnology.com wrote:
On Sat, 29 Aug 2020 16:34:57 +0100, TTman <kraken.sankey@gmail.com
wrote:

On 29/08/2020 15:54, jlarkin@highlandsniptechnology.com wrote:
On Sat, 29 Aug 2020 15:23:59 +0100, TTman <kraken.sankey@gmail.com
wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

If it\'s a coax, you can force an audio-frequency current into the
shield (it\'s probably grounded somewhere out there) and snoop for the
magnetic field. I\'ve found wires inside walls, by listening for the 60
Hz field when there was current in the wires.

It would probably work with an unshielded pair, too.

UK uses 2 twisted pairs( 1 is spare for residential use) in plastic
outer. No shield.

What sorts of data rates do you get over an unshielded buried twisted
pair?

ADSL is good for up to 8Mbps down and 448kbps up back to the exchange.
ADSL2+ (current offering) will do 22M/1M on a good day but not for me.

Speed is intimately related to line attenuation and distance. I get
about 5Mbps/1Mbps on a 5km 1960\'s copper line back to the exchange. Less
if it is windy or the beck is in spate and the cable ducts flooded with
water. Combination of overhead lines and buried so worst of both worlds.

Fibre to cabinet will get you closer to 80Mbps down 20Mbps up. That
typically leaves only the last 500m on copper twisted pairs.

The graph at the bottom of this page shows the distribution of speeds
and technologies in the UK at present (well in 2014).

https://kitz.co.uk/adsl/fibre-optic-broadband.htm

FTTrN sank without trace some while ago. Some diurnal variation in SNR
as continental radio broadcasts interfere a bit after sunset.

I\'m getting 120/40 Mbits at home from the cable TV provider, which is
shockingly better than what we got over old soggy twisted pairs from
AT&T.

Cable TV is only available in cities.
My brother in law gets 350M down/35M up on that with a cable TV feed.

We have some friends in a small town with horrible internet, so one of
their neighbors bought a microwave dish pair (amazingly cheap) and
shoot across Tomales Bay to connect their neighborhood. At work we
have a dish on the roof for internet and IP phones. It would have been
a big deal to jackhammer the sidewalks to run fiber to our place.

 

[Clive Arthur]

On 29/08/2020 15:23, TTman wrote:

I\'m planning digging up my concrete drive and lawn. A BT cable to the
house runs under both. I tried finding where it went using a metal
detector to no avail. Any other way to trace where the cable runs ?
I know BT engineers inject a signal into a pair to do a trace that way...
Any one any practical solutions ?
I\'d hate to chop the cable and be without B/band for ages

Any way you can warm it up so you can use a thermal imaging camera?

--
Cheers
Clive

 

[AIOE]

UK ???

Never heard of Fox and Hound signal tracer ?
Harbor Freight or other places .

 

[Martin Brown]

On 31/08/2020 21:13, John Larkin wrote:

On Mon, 31 Aug 2020 20:17:11 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 29/08/2020 17:57, jlarkin@highlandsniptechnology.com wrote:

I\'m getting 120/40 Mbits at home from the cable TV provider, which is
shockingly better than what we got over old soggy twisted pairs from
AT&T.

Cable TV is only available in cities.
My brother in law gets 350M down/35M up on that with a cable TV feed.

We have some friends in a small town with horrible internet, so one of
their neighbors bought a microwave dish pair (amazingly cheap) and
shoot across Tomales Bay to connect their neighborhood. At work we
have a dish on the roof for internet and IP phones. It would have been
a big deal to jackhammer the sidewalks to run fiber to our place.

The rural fast solution in the UK is a peer to peer (actually there are
supernodes) microwave network. From the antenna size and available data
rates I\'d guess up in the 30GHz band somewhere. Particularly since there
is a very strict line of sight requirement and no trees in the way.

It is popular with farmers since you get reliable 20M symmetric links or
30/10 and they are typically on unreliable <1Mbps long copper circuits.
farmers also have nice tall farm buildings to get decent line of sight!

The local Superfast Yorkshire \"initiative\" is strong on branding but
weak on technical support as their webpage so clearly demonstrates!

http://superfastnorthyorkshire.com/wherewhen#page-content

The people running the actual services on the ground are much better and
offer an effective alternative to the poxy copper fixed lines. eg.
(the mixed aluminium and copper circuits are the worst by far)

http://signa-uk.com/moorsweb/hosting-packages-agreements/

I would have it myself but I don\'t have line of sight on a node.

--
Regards,
Martin Brown

 

[Martin Brown]

On 29/08/2020 17:00, Tim Williams wrote:

They don\'t have commercials for the equivalent of \"call before your dig\"
on the TV all the time over there..?!  Hard to avoid over here.  Please
check the web, or the phone book, before planning something so reckless!

Seems to be something like this over there,
https://www.national-one-call.co.uk/

There are a few places where there are strictly enforced \"no dig\" zones
typically around very high pressure gas pipelines. The one near me has a
50ft exclusion zone either side and a helicopter patrol once a week with
a leak detector. Apparently if it did rupture it would be 180dB at 100m.

There was a spectacular failure several decades ago, but most people
have now forgotten about it. The expected mode of failure if it ruptured
is exciting since the cold ethylene gas is heavier than air and will run
down the hill to the sewage pumping station which may well ignite it.

https://www.hse.gov.uk/pipelines/ukopa.htm

However, most street digging is pretty hit and miss. Especially with the
plastic gas pipes buried in the 1970\'s with no foil tape on to find them
again. We were involved in an early ground penetrating radar to try and
locate them. The official maps tend to be quite inaccurate so it is
always wise to dig with the utmost caution in city streets.

--
Regards,
Martin Brown

 

[server]

On Wednesday, 2 September 2020 10:38:40 UTC+1, Martin Brown wrote:

There are a few places where there are strictly enforced \"no dig\" zones
typically around very high pressure gas pipelines. The one near me has a
50ft exclusion zone either side and a helicopter patrol once a week with
a leak detector. Apparently if it did rupture it would be 180dB at 100m.
...
However, most street digging is pretty hit and miss. Especially with the
plastic gas pipes buried in the 1970\'s with no foil tape on to find them
again. We were involved in an early ground penetrating radar to try and
locate them. The official maps tend to be quite inaccurate so it is
always wise to dig with the utmost caution in city streets.

Many years ago a high pressure natural gas main was ruptured by digging
close to the boundary of Guy\'s Hospital and Snowsfields in London.
I think it took an hour or so for the gas company to find the appropriate
shutoff valve. According to a colleague who was there at the time the
noise was extremely loud even on the other side of a multi-storey
building. Fortunately the gas did not ignite.

Later in the same area I saw an excavator that had fallen into a forgotten
tunnel while it was digging on the site of a new building. That part
of London is very cluttered underground and many records were lost and
underground structures forgotten as a result of WW2 bombing damage.

John

 

[Don Y]

On 9/2/2020 2:38 AM, Martin Brown wrote:

However, most street digging is pretty hit and miss. Especially with the
plastic gas pipes buried in the 1970\'s with no foil tape on to find them again.
We were involved in an early ground penetrating radar to try and locate them.
The official maps tend to be quite inaccurate so it is always wise to dig with
the utmost caution in city streets.

Utilities in (under) the street -- or sidewalks -- are fairly well documented,
here. But, once you leave the main feeders and move onto \"private property\",
there are no real records that can be consulted.

And, the folks who come out (free of charge) from EACH of the utilities
when you indicate that you\'ll be digging on your property are pretty
cavalier about their work. They often \"detect\" the line (gas, electric,
phone, water, etc.) in a few places and then INFER that it continues
in a straight line \"between the dots\". (different color spray paint
used to mark the ground for each utility\'s lines when you request this
service).

And, they only guarantee their work to ~36 inches (i.e., if you dig more than
36 inches from their marks and hit a buried service, THEY are on the hook for
the repair, else YOU!)

Local gas company sent a guy out to mark our service. When the work crew
came out a few days later (servicing the electric), I looked at the markings
and told them that the gas company guy had made an error in marking where
the gas lines ran.

Of course, they ignore \"silly homeowner\".

Then I told them that I had watched them excavate and install the gas main
a few decades ago and could tell them EXACTLY where it was routed.

(\"Hmmm... maybe we\'d better humor this guy?\")

Amusing to see their reactions when they realize that if they\'d ignored
my warning and assumed the markings were correct, we\'d have likely had a
gas leak when they INTENTIONALLY tore into the space that the markings
claimed was free of services!

 

[Martin Brown]

On 29/08/2020 17:03, Ricketty C wrote:

On Saturday, August 29, 2020 at 11:35:57 AM UTC-4, TTman wrote:


Silly questions first. Will the utility company do it?

They may do, at a \'silly\' price...

Around here it\'s free, Miss Utility. They don\'t want you mucking up
their wiring either. Are you sure they charge for that?

Hell yes. And they will charge you even more if you dig up their
services and break them.

Most spectacular one we had was a decade or more ago when a farmers
hedge flailer took out an entire telecoms cabinet. Lots of coloured wire
spaghetti and no phone service at all for a fortnight!

--
Regards,
Martin Brown