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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 | 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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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Re: A wire is a wire is a wire 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
| Re: A wire is a wire is a wire 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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TakeTheFifth
join:2004-04-20
Anjou, QC
1 edit | Re: A wire is a wire is a wire 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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Angelo_
The Network Guy
Premium
join:2002-06-18 | 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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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs: | Re: A wire is a wire is a wire 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
| Re: A wire is a wire is a wire 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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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs: | Re: A wire is a wire is a wire Is it paper tape or cotton-based hockey tape? | |
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Bicephale
join:2005-09-24 | No problem, i can move the tubing ground to a 2nd block in order to stick to the book. | |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| 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..
| Re: A wire is a wire is a wire 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
| Re: A wire is a wire is a wire said by Bicephale :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. Not likely. The NID is probably required to be accessible without a ladder.
--
Need-based health care not greed-based health care. | |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Re: A wire is a wire is a wire
Bell's Main with Tape - Abrasion |
Hi ArthurS,
What's most interesting about the tie wraps is the
likelyhood that these were not part of the initial
installation when the house was built thirty years
ago. As i wrote before, this raises a fundamental
question relatively to the tape's purpose: was it
curative or simply preventive? In any case, there
is nothing left on our side of the demarcation box
which will require further attention! My expenses
reached a point where DSL isn't attractive anymore
if i consider that it made me buy two 25' rolls of
EtherNet cabling and two switches, one spare MoDem
because GNet bashers made me doubt without showing
the numbers, two RJ-11 phone connector boxes, iron
tubing (plus craftwork as a supplement), alligator
clips and an RJ-11 cord to match, one ground block
(to stick to the book), not to mention many months
of my own time spent over trouble-shooting... For
all i know, very few customers would even consider
going through all this extravaganza. Anyway, it's
impossible to set an NID over the entry point so i
suppose right above Hydro's counter should be good
enough - once the tape issue has been addressed...
By the way, maybe the tape was installed solely as
a protective ribbon but the image from above shows
that Bell may be better not to use tape like this!
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| The NID normally should be located where the wire enters into the building. You might find it a bit tough to convince the tech to replace everything, most have the attitude "that if it ain't broke, don't fix it"! Careful testing is the best way to show that there is a problem here, much of it can be attributed to sloppy workmanship inside and perhaps outside the house. Their responsibility ends at the NID, beyond that is on YOUR dime and responsibility! | |
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ArthurS
Watch Those Blinking Lights
Premium
join:2000-10-28
Hamilton, ON
| Re: A wire is a wire is a wire said by DKS :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. Not saying that they aren't UV resistant tie wraps, but judging from the nature of the rest of the installation, all bets are off that such UV-resistant tie wraps have been used!  | |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| I guess I should explain a little about that graph. I have two DSL lines and have had CRC errors on both at times. I wanted to quantify how much various error rates affected the download throughput. I have several kitchen appliances, an ancient food blender, that I knew caused errors on both lines and another appliance, an electric oven/range that only affects the faster line.
I would run a large (16-64 MB) FTP download using an FTP program that times the download to the hundredth of a second. While the download was in progress, I then used the appliances to generate CRC errors. The modem's CRC counter was checked before and after the end of the FTP download. The throughput speeds of the error-impaired tests were normalized to the throughput of an error-free download.
CRC errors cause TCP/IP packet loss. So the download throughput speed during a burst of CRC errors is contingent on the recovery of the TCP/IP re-transmission which is in turn affected by the size of the TCP/IP window (I used a 63888 RWIN), the upload sync speed, etc.
Another factor affecting the download throughput speeds is the "clustering" of the CRC errors. A cluster of errors over a small fraction of a second may not cause as much slow down as the same number of errors evenly spaced over seconds time. I think my stove puts out more evenly spaced errors while the food processor's errors were more clustered. On the chart above, the stove was used to error the 6016 line and the food processor was only used on the 1536 line.
As they say, "your mileage may vary" from that in the graph. | |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| I've tested my DSL on back up battery power before and it didn't reduce my error rate when I intentionally tried to generate CRC errors. The impulse noise in my electrical lines from those noisy devices is transferred to the wiring in my phone drop by inductive coupling and not through the modem's power supply.
I would recommend that you try to find exactly which electrical devices are causing your errors if you can by powering up individual devices and checking the error counts in the modem. Once you know which devices (I'm assuming that not all devices will cause problems) are causing the errors, then you can jump to testing how much they might affect your download speeds using the method I explained above. When you know how much various error/rates affect your download speeds, then you can target a necessary reduction of the error rates that you can live with and/or afford to have what you consider acceptable download speeds.
You may find that the error rates you are currently seeing hardly affect your download speeds in which case you might be able to live with them. | |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Re: A wire is a wire is a wire Hi again d_l,
DSL devices are so sensitive i bet this technology
could be used to send messages to Mars, euh... It
wouldn't surprize me that parasitic capacitance is
enough to couple the MoDem to the 60 Hz AC circuit
through its EtherNet cabling, even if an isolation
transformer stands in the path. I wonder, does it
really suffice to run it on battery power or would
i not also need to unplug everything but the line?
This is wild speculation, all i can tell right now
is that the stove is most definitely involved. My
preliminary attempts to shield Bell's main outdoor
weren't conclusive - it's thinner, slotted and the
missing ground lead means that the metal sleeve is
"floating", after all, and requires a revision!...
Trying to measure the error rate simultaneously to
the transfer rate sounds like quite a challenge at
the moment. I'd need to make sure it's CRC errors
which cause lower speeds and i could identify only
one peak per hour so far. You see, i'm not facing
one but two issues; sometimes the phone line will
keep steadily quiet for days with the exception of
kitchen activity but there are days when the noise
is most likely external to our home... During bad
days it doesn't help to measure noise because this
disturbance coming from nowhere will mask reality,
no matter if the stove is being used or not. I've
considered buying a new MoDem, the 4th one i'd try
so far, but my experience with the SpeedTouch left
me with the opinion that newer products just carry
economically-based design optimisations if any!...
You mentioned the SpeedStream 4100B because it has
better rejection of the noise induced electrically
by household appliances. Doesn't this device sell
as a "decomissioned" (customized) refurbished unit
from Bell, etc., or are there suppliers who happen
to have some SS4100B with generic FirmWare? 'DMT'
is a precious tool for me, would it work on it?...
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Angelo_
The Network Guy
Premium
join:2002-06-18 | map the wire :P | |
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Angelo_
The Network Guy
Premium
join:2002-06-18 | what do you got against the 516 its so great much better then my 3com i bought... and let me tell you what a waste taht was! | |
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See 6 replies to this post | |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Re: A wire is a wire is a wire Note.:
I've concatenated the present thread as a one-time
post which became my conclusion for this other one
because together they cover the wiring part fully:
The customer's own wiring, Bicephale, 2007-Oct-30
I also addressed configuration aspects thru a link
to my "tweaks" thread, which completes the picture
as far as an average customer will be concerned... | |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Bonjour Old Computer,
I want you to see this, the ferrite trick works so
well i find it hard to believe. See for yourself:
Tweaks, Bicephale, 2008-Jan-14
It seems i'm accumulating paradoxal static records
here! Sometimes what your see isn't what you get:
%20.PNG)
SpeedTouch 516 Tweaking :), Bicephale, 2007-Dec-11
J'ai beau informer les gens de cette situation, il
semble que même les usagers réguliers du forums ne
remarquent pas les avis en grosses lettres rouges:
SpeedTouch 516 Tweaking :), Bicephale, 2008-Jan-11
Peut-être aurez vous des arguments convainquants à
formuler, moi j'ai eu beau essayer on m'ignore!...
Perhaps you have better teaching skills than i do,
your input on these contradictory readings is more
than welcome. Your experience with radio HardWare
might be usefull, can you shead some light for us?
For example, how come do i worsen attenuation just
by removing toroidal chokes on the DSL phone input
considering we could expect the signal to be a bit
stronger once it's been taken off? Is it possible
that what i've got here is acting like a "loading"
coil but for DSL frequencies? Lets not forget the
SNR Margin numbers and Spectral Response curves...
Am i right to think it's ironic to obtain mediocre
noise performance with an SNR Margin of almost ten
more dB, not to mention the nicer spectral curve?!
I thought this was an interesting riddle you might
want to know of. What's on your tongue? Tell me!
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