Searching \ for '[EE]: finding underground cables' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=finding+underground
Search entire site for: 'finding underground cables'.

Exact match. Not showing close matches.
PICList Thread
'[EE]: finding underground cables'
2003\08\07@064410 by Reelf Monsees

flavicon
face
Hi,
I've got the 'nice' task of finding some underground communication-
cables in an area that is now overgrown with trees, shrubbs etc. Some
of the connection-boxes that connected the different cables are
missing / destroyed. The area measures about 100 square-kilometers,
so starting to dig in order to search for the cables is pointless.
There are devices that transmit signals into these cables and receivers
that detect the signal spreading out along these cables.
Does anybody have some ideas or even schematics for a transmitter
and receiver ?

regards,
   Reelf

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@073716 by Vasile Surducan

flavicon
face
There is a standard scheme if the line is not broken.
At one side of the cable a 50 to 100W audio power amplifier is sending
on line 1kHz low frequency modulated signal. The other end of the line is
short scurtcircuited. The receiver is a coil, an audio preamplifier and
a pair of headphones on your ears.
The biggest problem is if you have an iron pipe near  your
undergrown line, the effect is you go on pipe and not on cable...
because of parasytic inductions.
From my experience, founding lost cables is a nasty job.

top 10 wishes,
Vasile
http://surducan.netfirms.com


On Thu, 7 Aug 2003, Reelf Monsees wrote:

{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@080451 by Reelf Monsees

flavicon
face
That's something to start with. The problem is, that most of the cables
are broken or the connection-boxes have been destroyed and the end of
the cables are somewhere in the ground underneath earth, gravel, bits
of stone and concrete where houses have been before.
So inducing a signal into one end (we know where the cables begin)
would be the best idea.
regards,
   Reelf

Vasile Surducan schrieb:
{Quote hidden}

-- SyWiTec *  Systeme für Wissenschaft und Technik
            Bamberg & Monsees GbR
        Steindamm 22 * D-28719 Bremen
  Fon +49-421-646775 * Fax +49-421-646785
            http://www.sywitec.de/

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@082148 by Bob Axtell

face picon face
You might have good results with a simple metal detector. As you pick up
the metal in the wire, walk down in each direction to plot its extent. Most
cables, even power cables, are only buried a foot or two down.  All
Electronics has an eddy-current type "treasure" detector, for $37 USD,
http://www.allelectronics.com  , I think.

--Bob


At 12:41 PM 8/7/2003 +0200, you wrote:
{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@083619 by Reelf Monsees

flavicon
face
Hm, also thought about that. Maybe I could induce a signal into the cable anyway and use a search-coil to pick up the signal.
Building a search-coil with an amplifier (filtered input of course,
so only the frequency of the induced signal is amplified) is not a
problem. Any idea how to induce a signal into the cable ?  Could be
done inductive or direct as all cables are switched off.

regards,
   Reelf

Bob Axtell schrieb:
{Quote hidden}

-- SyWiTec *  Systeme für Wissenschaft und Technik
            Bamberg & Monsees GbR
        Steindamm 22 * D-28719 Bremen
  Fon +49-421-646775 * Fax +49-421-646785
            http://www.sywitec.de/

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@085109 by Bob Axtell

face picon face
Well, that MIGHT work, actually. I'd induce a very powerful signal at about 60khz. Several sites on the web indicate that 50khz-75Khz seems to propagate through rock and earth pretty well (search for CAVE RADIO links).

--Bob


At 02:35 PM 8/7/2003 +0200, you wrote:
{Quote hidden}

---------------
NOTICE

1. This account can accept email & attachments up to 10M in size.
2. Federal Monitors: At request of client, some attachments are encrypted. Please DO NOT delay traffic; please reply with credentials for password.
--------------

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@090121 by Reelf Monsees
flavicon
face
okay, also found some hints that indicate that 33 kHz to 133 kHz is
a good range. No problem in generating the signal. But now it comes
to coupling it to the cable. What would be best, using two cores of
the cable (up to 140 of them in one cable) or the cores and ground ?
And how would the coupling be done ?  As the state of the other end
of the cable is unknown, it can't be assumed that we get a current
flowing.

regards,
    Reelf


Bob Axtell schrieb:
{Quote hidden}

-- SyWiTec *  Systeme für Wissenschaft und Technik
            Bamberg & Monsees GbR
        Steindamm 22 * D-28719 Bremen
  Fon +49-421-646775 * Fax +49-421-646785
            http://www.sywitec.de/

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@091248 by Vasile Surducan

flavicon
face
There is a methode called "burning a cable". Is often used in
10KV and 30KV underground cables. When a cable have a bad isolation
between a phase wire and the iron mantle, it's applied a short high
voltage/energy pulse which is making a shortcircuit in the defective
place. Then a higher current flows through the cable till that place.
But if the cable haven't an iron mantle ?  maybe a pulse between two
wires?

On Thu, 7 Aug 2003, Reelf Monsees wrote:

{Quote hidden}

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@091912 by Denny Esterline

picon face
This probably isn't helpfull at all, but:
I'm curious as to what you plan to do with them after you find them?
My thinking is that if they were lost / abandoned long enough ago for the
area to be overgrown, I don't think I would trust using them for anything
'misson critical'. Unless there's somthing I don't understand (there always
is), I'd just run fresh where you need them, and move one.

BTW, I don't know where this is all located, but here in the states we have
a service called Miss Dig. I don't have a phone number handy, but the're
listed. It's a free, coordinated service to have all the utility companies
locate and mark underground services, before you dig. Call them first, even
if you know there isn't any utilities where your going to dig.

In a nutshell, it's a liability transfer. If you play by thier rules, and
break somthing they didn't mark, your not liable.

Denny

{Original Message removed}

2003\08\07@092120 by Reelf Monsees

flavicon
face
Yes, we have done that on other locations with energy-cables. The
'sparks' are audible with microphones touching the ground. Already though of that, but we can't do this here. Too dangerous as the
sparks might cause not only damage to the cable but as some of the
cables might end in a forrest or grass, we might cause serious fires.
No rain for a long time, everything is dryed out. I'm just looking up the links for 'Cave Radio', maybe I can get some
idea how to induce a strong enough signal into the cables.

regards,
    Reelf

Vasile Surducan schrieb:
{Quote hidden}

-- SyWiTec *  Systeme für Wissenschaft und Technik
            Bamberg & Monsees GbR
        Steindamm 22 * D-28719 Bremen
  Fon +49-421-646775 * Fax +49-421-646785
            http://www.sywitec.de/

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@094156 by ubrey McIntosh

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 02:35 PM 8/7/2003 +0200, you wrote:
>Hm, also thought about that. Maybe I could induce a signal into
>the cable anyway and use a search-coil to pick up the signal.
>Building a search-coil with an amplifier (filtered input of course,
>so only the frequency of the induced signal is amplified) is not a
>problem. Any idea how to induce a signal into the cable ?  Could be
>done inductive or direct as all cables are switched off.
>
>regards,
>     Reelf

A toroidal Rogowski coil come to mind, but I have no experience with them.

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com>

iQA/AwUBPzJUYwKlSw8yssF7EQK8jwCgya36V5O5Ss+C/NYckY12x5CJIxMAoMay
yuBjSFmsapWzWMvJxRT3P8NX
=H41r
-----END PGP SIGNATURE-----

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\07@111350 by Tim ODriscoll

flavicon
face
On Thu, 7 Aug 2003, Reelf Monsees wrote:
> I'm just looking up the links for 'Cave Radio', maybe I can get some
> idea how to induce a strong enough signal into the cables.
>
We used to have something called a 'Tone Tracer' at work. We used it for
finding which cat5 cable we wanted from a bunch of them going between
buildings. You clamped two wires in the cat5 cable to the tone generator
and went over the other end of the buliding with the receptor which would
resonate with the tone generators' frequency and start to squeal loudly
when it got near it. There was a sensitivity adjuster on the receptor so
you could identify which cable you wanted out of a bunch of 20 or so.

Not sure how much help that is, as I 'spose you need something with
a bit more grunt to it to get through the ground :/

Good luck anyway,

Tim

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2003\08\09@094002 by Peter L. Peres

picon face
It this had been for your garden I'd have said build one or use ham radio
equipment to do it (vlf transmitter connected to cables + receiver used as
sniffer).

However for 100km^2 I will definitely tell you to talk to a local building
contractor, gas company, etc and *rent* a perfectly working set for a
month or so.

Peter

--
http://www.piclist.com hint: To leave the PICList
spam_OUTpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu

2003\08\09@094004 by Peter L. Peres

picon face
> Several sites on the web indicate that 50khz-75Khz seems to propagate
> through rock and earth pretty well (search for CAVE RADIO links).

Actually you want a frequency that is attenuated rapidly by the earth so
the cables are found, not the parts of the earth that are dry (concrete,
sand) or hollow (buried basement) (I used to work in geophysics
prospection gear). 1-1.8MHz is good for this although some lines may
resonate at 100km^2. Too bad, tune the transmitter ;-)

Peter

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestKILLspamspam@spam@mitvma.mit.edu

2003\08\09@094008 by Peter L. Peres

picon face
> okay, also found some hints that indicate that 33 kHz to 133 kHz is
> a good range. No problem in generating the signal. But now it comes
> to coupling it to the cable.

You couple it single-endedly. The other end needs a ground plane of some
sort. An earth point or a large metal structure will help. Check that it
is not connected to the cable ... None of this will work if the cable runs
in metal conduit. Then only metal detectors will work right. I recommend
the proton precession gradiometer kind. If the metal was in the ground for
a long time then this should work perfectly (gets nicely megnetised by the
earth field). You will also find all the water and gas pipes, sewers
(manholes etc) and rebars in the concrete ...

Peter

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestspamKILLspammitvma.mit.edu

More... (looser matching)
- Last day of these posts
- In 2003 , 2004 only
- Today
- New search...