Bicephale
join:2005-09-24
 ·TekSavvy Solutions..
| A wire is a wire is a wire
Man-made noise | 
Probable cause | |
This post is special, it demonstrates how wrong it
may be to think that a wire is a wire is a wire...
Guess what happened on the 7th day of a test which
i started a week ago: no noisy peak at congestion
hours contrary to six previous records! Our house
was empty so i immediately became suspicious about
the kitchen phone but it didn't seem involved so i
started to light up appliances as when somebody is
preparing a meal and voilà!!! A nice peak finally
showed up (A), my timing was correct but how could
this wireless phone pick up so much noise from the
micro-wave oven, the fluorescent lamp or even some
power-hungry unit like the stove, etc? Mystery...
At the begining of each hour i powered everything,
it turned out that the room for coïncidence shrank
gradually after each test (B-H), noise peaks being
added in a reproducible way! No doubt was allowed
in my mind: the peaks still occured even with the
phone completely disconnected so i concluded there
was something quite wrong about the whole kitchen!
It was quite puzzling but one possibility remained
which i thought was purely theoretical: there had
to be some pretty strong 60 Hz noise involved so i
walked into the room where the electrical panel is
located and then i discovered some probable cause:
despite the utmost disbelief i couldn't but notice
all of the phone wiring including Bell's main were
tightly packed against a trunk of electrical wires
by three stiff #10 gauge stitches spaced from each
other by nearly eighteen inches, my father's doing
unless an electrician did it during his visit many
months ago! Once i understood what was going on i
disconnected all of the phone lines but that which
goes to my MoDem, forgetting that Bell's main also
coupled to 60 Hz noise... Instead of a faint peak
i got one which was still strong, maybe because of
improper loading, i wonder. Anyway, the next test
was done with every line connected (just as usual)
but with a twist: i took away the stitches to let
all of this wiring loose. The peak didn't go away
but my seven days test was over and it was late so
i decided to sleep on it. My next move will be to
redo the wiring so that no phone line is too close
to high capacity 60 Hz electrical cabling. I hope
that's all i must fix - More tests are required...
 |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
1 edit | reply to Bicephale
Re: A wire is a wire is a wire
Yikes! What a mess! I hate to see the rest of the wiring!
A few points:
1. This is clearly an electrical code violation. Low voltage wiring (CATV, telephone, data) must be kept separate from high voltage (120 VAC) wiring!
2. Distance is your friend. For every doubling of distance, you noise goes down an order of magnitude (inverse square law here). I would try 6 inches separation at the very least, especially close to any significant current carrying conductors.
3. Be careful how you bundle/route your wires, particularly your data cables. Interference rejection is dependent on the consistency of the twist in the wire pairs. Using zip ties wrapped tightly around cable, routing cable around sharp corners, snagging wire into knots disturbs this twist pattern, making another point of entry for noise.
Let us know how you do!
Edit: I advise caution when dealing with a rat's nest of wire so close to AC power wiring! I would turn off AC power at the breaker panel before messing around there as a safety precaution! Under the right conditions, 120 VAC can kill! |
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Angelo_
The Network Guy
Premium
join:2002-06-18 | reply to Bicephale
last visit the tech spliced the cable and made a huge mess (why my line can't sustain speeds at the new snr's |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| reply to ArthurS
Hi,
I increased the distance between the AC wiring and
Bell's main (including its ground wire) but i left
the internal phone lines in place. This is only a
temporary configuration because it must go back in
the wall somehow, eventually... The sampling rate
being fifteen minutes these tests are very slow so
i need to be very patient before i can evaluate my
error rate reliably. I tought of using galvanized
steel tubing because it would shield my DSL signal
against electric and magnetic fields, i guess, but
i prefer to evaluate simpler remedies for a while:
maybe displacing the demarcation box would suffice
to fix this issue permanently (i once had a 6 Mbps
profile without much trouble, after all!) but then
i'd probably need to displace the MoDem as well so
i'm considering my alternatives. In the meantime,
the possibility that a pair of stacked filters may
not have enough punch at low frequencies to reject
60 Hz noise is a big concern, i might have to move
the other phone lines for the duration of the next
few tests to the very least! I wish i could do my
little experiments using the SpeedTouch so i asked
about Linux Live CDs (in the TekSavvy forum) but i
doubt this will be sucesssful as it wasn't before.
After six months of wondering, my nightmare may be
over, finally. I can now turn my frustration into
a renewed motivation to improve the situation. It
seems i got no choice but to grasp the opportunity
to reduce the negative effects of cross-talk which
are bound to grow while DSL gains more popularity!
 |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| said by Bicephale  :I tought of using galvanized steel tubing because it would shield my DSL signal against electric and magnetic fields, i guess, but i prefer to evaluate simpler remedies for a while: maybe displacing the demarcation box would suffice to fix this issue permanently (i once had a 6 Mbps profile without much trouble, after all!) but then i'd probably need to displace the MoDem as well so i'm considering my alternatives. In the meantime, the possibility that a pair of stacked filters may not have enough punch at low frequencies to reject 60 Hz noise is a big concern, i might have to move the other phone lines for the duration of the next few tests to the very least! I wish i could do my little experiments using the SpeedTouch so i asked about Linux Live CDs (in the TekSavvy forum) but i doubt this will be sucesssful as it wasn't before. After six months of wondering, my nightmare may be over, finally. I can now turn my frustration into a renewed motivation to improve the situation. It seems i got no choice but to grasp the opportunity to reduce the negative effects of cross-talk which are bound to grow while DSL gains more popularity! Even galvanized steel pipe is limited in its shielding from low frequency (60 Hz) electromagnetic fields. For best results, use rigid galvanized conduit (yes it's the most expensive kind of conduit and a pain to work with), and maintain a separation of at least 6 inches between high voltage and low voltage (which is required by code). In my specifications for high end commercial applications, I insist on one foot minimum, with both AC power and low voltage wiring being in separate conduits. In your situation, maximizing separation distance between the two is the cheapest and most cost effective solution for home use.
There is a lot to be gained from a neat installation. Starting over and doing it right sometimes is the best option. |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| 
60 Hz Noise - The AC coupling is actually revealed! |
Hi Angelo168,
My numbers ain't as accurate over a few hours than
they can be over a week so i better hold judgement
based on them until enough records collect but the
graphic shown above should speak for itself! This
looks like some threefold improvement to me and it
also suggests i only need to shield Bell's main as
it turns out there was only a single phone instead
of the whole wiring when the 18 h peak occured: i
put back the original circuit for the 19 h peak so
that's a strong indication that the stacked double
filter setup does work at 60 Hz, after all... The
single phone provided some loading and i put it at
a good distance from the electrical panel in order
to control noise pickup; there should have been a
difference in the peak's amplitudes if the filters
couldn't keep the 60 Hz noise away compared to the
reference load. Great, i was quite concerned that
having Bell's main besides of the home wiring in a
close shielded space might actually couple them to
a point that noise from the house wiring would end
up being injected on the main line anyway - i just
hope the impedance won't be affected too much once
i'm done inserting the wires into the 1" sq. steel
tube i've found! Well, at least there's no splice
to deal with and the shielding tube just needs the
length to be cut then i must get screw-pads added.
Piece of cake!
 |
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TakeTheFifth
join:2004-04-20
Anjou, QC
·ELECTRONICBOX
1 edit | I would be more concerned about interference riding the power lines than the 60Hz signal itself: hi-frequency junk (from electric motors, arc welders, amateur radio, etc). If have seldom seen nice and clean sine wave house power; If you live near any kind of garage, industry, machine shop (or are on the same power grid), and you suspect your problems are related to power line interference, they would be the culprit. At any rate, keeping phone lines away from power lines is a good idea (and if you can avoid having them run parallel, even better).
Some other sources of RFI: »cable-dsl.home.att.net/#RFI
Phil |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
1 edit | Hi Phil,
I'd like to use a more descriptive expression than
just the term "60 Hz noise", which is quite vague,
but my GNet only provides a simple diagnostic tool
through 'DMT' and my SpeedTouch even less. In any
case, i did suspect there was a wider problem this
winter and i still do so the next step would be to
put the MoDem on battery since that's all i can do
about such external nuisance; when it comes to AM
radio stations and storms i'm short of imagination
but it wouldn't matter with these numbers, though:
Source: GNet BB0060B
Date: 2007-Sep-8
Time: 11:27:52
Bits-per-Bin: 13
UpStream Bins: 6 to 31 inclusively
DownStream Bins: 33 to 254 (idem)
Tx Power Attm.: -1 dB
Coding Gain: 7 dB
Up Time: 12:12:37 (43957 sec)
Local CRC: 142/day (72/43957 sec)
Remote CRC: 16/day (8/43957 sec)
Local HEC: 90/day (46/43957 sec)
Remote HEC: 4/day (2/43957 sec)
Local Tx Power: 10.95 dB
Remote Tx Power: 19.40 dB
Local Line Atten.: 31.5 dB
Remote Line Atten.: 29.0 dB
Local SNR Margin: 18.5 dB
Remote SNR Margin: 8.0 dB
Even a twelve hours record has little meaning here
and i don't believe this is the end of peak rushes
but that's nowhere near a thousand errors per day,
(around four thousand until recently to be exact)!
As i wrote, the wires got to go back into the wall
so there's no other way to manage with the limited
space than by shielding Bell's main while the rest
of the phone lines are moved by a few inches only.
Thanks for your link, i already feel apprehensive!
 |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| reply to Bicephale
%20.JPG "116981 bytes")
Bell's Main #1 (with tape) |  .JPG/thumb.jpg "124084 bytes")
Bell's Main #2 (with tape) | 
Bell's Main Outdoor Path | | | 
Bell's Main Entry Point | 
Iron Tubing - Arrival | 
Iron Tubing - Corner | 
Iron Tubing - Exit | 
Demarcation Point | 
Direct Connection Cable with Alligator Clips |
I'm done shielding Bell's main line with a pair of
1" sq. tubes made of iron steel. Today was a nice
sunny day so i also used the opportunity to gather
images of the whole thing, starting from the roof!
It seems only two items might go wrong about this:
1)
the tape around Bell's main on the roof because
someone might have put it there for a reason...
2)
the possibility that long tubes made of ferror-
magnetic material such as these might happen to
modify the characteristic impedance at the high
DSL frequencies enough to disrupt the signal...
Euh... Oh, i almost forgot to mention that a part
Hydro's main tubing appears to be made of plastic!
|
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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs: | Hmmmm. Bell would also not like you piggybacking on their ground. I believe it is supposed to be exclusive. |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| said by DKS :Hmmmm. Bell would also not like you piggybacking on their ground. I believe it is supposed to be exclusive. Although this situation seems unique, any form of metallic "conduit" should be bonded to ground, this is a code requirement. All grounds must be all bonded together at the service entrance--this includes the main ground electrode for the building's power, along with the grounding conductor from the lighting arrestors for any telephone or cable TV/antenna that's penetrating to inside the building. |
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Bicephale
join:2005-09-24 | reply to DKS
No problem, i can move the tubing ground to a 2nd block in order to stick to the book. |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
2 edits | reply to ArthurS
Bell's Main with Tape - Front View | | 
Bell's Main with Tape - Bottom View |
Yeah, that's tape all right! Tissue tape i'd say.
A technician working for Bell explained to me that
he could see a high-impedance short (my own words)
across the line this winter. The problem resolved
by itself and didn't show up until recently when i
noticed, once again, that pulse hammer-dialing "9"
temporarily fixed my DSL connection which remained
dead for hours otherwise... I suspected that some
chemical reaction was involved, it seemed like the
successive 40 volts pulses caused a faulty section
of the telephone line to depolarize but none of us
had the least clue where it was taking place. The
more i look at this tissue tape the more i wonder:
after years of exposition to the elements it could
be collecting moist, a disaster waiting to happen.
I wonder if it's standard procedure at Bell to use
tissue tape in this manner since i'd have expected
to find a completely different type of protection!
 |
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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs: | Is it paper tape or cotton-based hockey tape? |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Hi DKS,
I haven't got a chance to reach it so far, meaning
this may be nothing more than a form of protection
against abrasion - which makes me somewhat worried
nonetheless: was it preventive or curative when a
guy decided to put it there years ago?... I don't
like how it appears to change shape and direction,
if that's a splice i wouldn't bet on the odds that
whoever did this he had a soldering iron handy and
a helper down below, to disconnect the power right
before he got ready to touch one of the wires. My
photographs are inconclusive but my instinct tells
me someone will have to look under the tissue tape
because, from the looks of it, there's very little
silicone-based sealant covering that joint if any.
Well, the situation could be worst: one of Bell's
employees might actually have showed up while this
detail was still remaining unnoticed. Lucky me...
Anyway, i can't afford not to be curious about it!
 |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| reply to Bicephale
With the way things were wired inside your house, I'd say this tape is very suspect. If it is simply being used to prevent abrasion, I don't see any harm done, though surely there's a better way to secure the wiring to the house without having abrasion problems. Looking back at earlier pictures, I don't like seeing the use of plastic tie wraps to secure the wire to the utility conduit, UV rays will deteriorate the plastic within a few years.
If it's being used to hide a splice, I would insist on getting the entire cable replaced by the telephone company. |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Hi,
You're quite right to mention the nylon tie wraps,
thanks for bringing this detail to my attention!!!
Now i know for sure that someone must have climbed
up there much later than thirty-some years ago! I
wonder if Bell would agree to insert an NID before
the nuisances take place: e.g. on the roof, using
only the wealthy section which remains once all of
questionable items (like exposure to AC noise thru
PVC tubing or the possible moisture-related shunt)
have been excluded... This is called day dreaming
but should i happen to be around the next time one
of Bell's employees gets here i'll insist that all
this trash got to be fixed before i let him enter:
there's no point taking measures in hope he can go
away with it while predenting that the rest is OK! |
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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs:
·Bell Sympatico
| reply to ArthurS
said by ArthurS :Looking back at earlier pictures, I don't like seeing the use of plastic tie wraps to secure the wire to the utility conduit, UV rays will deteriorate the plastic within a few years. Interesting. The Ilsco brand ties I have aree UV resistant. The ties were installed in direct sunlight five years ago on my satellite dish and they are still strong and flexible. |
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