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Old 08-28-2012, 08:02 PM   #1
ssiikmuz

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Default Noisy phone line
We have a new office, and our Draytek 2710 modem/router that worked in the old office is struggling.

It will chug along at 5 errors/min (incoming data CRC) until the shop next door arrive for the day, then it constantly comes up with 50-100 errors/sec. When they go home for the day, the errors drop way down again.

We have isolated the power, running the thing from batteries with no change.

The Telstra tech tested the lines and gave them a clean bill of health.

The neighbouring shop is retail, so have nothing fancy plugged in, and use dialup for their internet. (In fact, they seem to be having problems with their dialup since we moved here)

Any suggestions? (systematically shutting down the neighbour's equipment until the problem goes away would be a good start, but they are not fussed on that idea)
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Old 08-28-2012, 08:44 PM   #2
cigsstorenick

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Oops... That was supposed to go into tech talk
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Old 08-28-2012, 08:54 PM   #3
Adamanta

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Sothe problem is on the ADSL side?
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Old 08-28-2012, 09:29 PM   #4
Zarekylin75

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The Telstra tech tested the lines and gave them a clean bill of health.

This only puts it withing the error limits of Telstra. This does not mean that the line is not bugged.

Asked for another check and actual test of the line and then call the Ombudsman.
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Old 08-28-2012, 11:33 PM   #5
saerensenatljn

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The Telstra tech tested the lines and gave them a clean bill of health.

This only puts it withing the error limits of Telstra. This does not mean that the line is not bugged.

Asked for another check and actual test of the line and then call the Ombudsman.
It probably puts it in the internal wiring of the building, rats chewed distribution cable in the roof, or something similar. The Telstra fella is only obliged to test to the network termination point, in your case it will be the building MDF, in a house its the first socket. Get the internal cabling checked before you go running off to the ombudsman or you could end up looking silly. If it is the internal cabling the Telstra fella could actually have charged you for the callout.
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Old 08-28-2012, 11:35 PM   #6
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It probably puts it in the internal wiring of the building, rats chewed distribution cable in the roof, or something similar. The Telstra fella is only obliged to test to the network termination point, in your case it will be the building MDF, in a house its the first socket. Get the internal cabling checked before you go running off to the ombudsman or you could end up looking silly. If it is the internal cabling the Telstra fella could actually have charged you for the callout.
The tech came and plugged his equipment into the actual phone jack we have our modem connected to.
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Old 08-29-2012, 12:00 AM   #7
snova

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Do a check on the previous owners?
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Old 08-29-2012, 01:00 AM   #8
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Not sure what calling the ombudsman will do? The minimum specification, Telstra has to provide was designed for voice, not data. If your line is better than the minimum specifications there maybe nothing the ombudsman can do.

I used to be a contractor to Telstra and based on your description, the problem could be crosstalk between your line and the neighbours. When you are using the landline you might hear your neighbours dialup modem in the background. Crosstalk faults can be difficult ones to solve if the line test is OK. They can be solved by changing the cable pair, one of circuits is on. If there no spare pairs there maybe nothing that can done.
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Old 08-29-2012, 01:07 AM   #9
minowz

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Would a line filter be useful in this kind of circumstance?
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Old 08-30-2012, 05:00 AM   #10
GotActichwicy

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Sometimes I have wondered if Telstra get a dodgy twisted pair and being short of pairs they shuffle them around.

You can get intermittent impulse type crackling on dodgy pairs, which may not show up in their tests.
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Old 08-30-2012, 04:14 PM   #11
IoninnyHaro

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I worked for them for near 40 years.

Answering the last 3 posts.
yzb, crosstalk always has a reason, it may not show up as a fault that can be tested with an ohmmeter but there's always a reason. Its possibly not something that a contractor would be able to pick up given the severe time limits that are put on them.

Furious. A line filter will not help.

Transition. Shuffling pairs around, again because of time limits per job some of this happens.
Crackling on dodgy pairs will show up on DC tests if the reason is a contact fault, low insulation resistance type of thing. if the noise is caused by a high resistance joint DC tests are little use, a careful look at the line with a pulse echo tester will show it as a spike but there are lots of other reasons for spikes as well and it takes quite a bit of experience to interpret properly, and sometimes multiple faults can mask each other and throw distance measurements out. It can often take considerable time to clear multiple faults, Telstra contractors and lineys aren't allowed the time to do it.

CS keep reporting the line as faulty, Telstra has trigger points that allow higher level investigations to take place, these are allowed as much time as it takes. Also if you keep reporting the fault it also triggers alarm bells at the ombudsmans office. You will have a history if you eventually need to take it there.
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Old 08-30-2012, 04:15 PM   #12
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CS keep reporting the line as faulty, Telstra has trigger points that allow higher level investigations to take place, these are allowed as much time as it takes. Also if you keep reporting the fault it also triggers alarm bells at the ombudsmans office. You will have a history if you eventually need to take it there. i know this from first hand experience when the electric fences were making my internet drop out.
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Old 08-30-2012, 04:30 PM   #13
AlexanderPalamayr

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i know this from first hand experience when the electric fences were making my internet drop out.
Electric fences are the hardest faults to fix, Telstra has no control over the way they are installed and maintained but must attempt to minimise the trouble they are causing. Outskirts of town everyone has a horse and an electric fence and most fences are faulty.
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Old 08-30-2012, 05:28 PM   #14
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>>>Electric fences are the hardest faults to fix, Telstra has no control over the way they are installed and maintained but must attempt to minimise the trouble they are causing. Outskirts of town everyone has a horse and an electric fence and most fences are faulty.

Maybe with long lines parallel to electric fences the induced pulses exceed the CMR abilities [slew rate limitations inclusive] of the buffer into the exchange, which would be in all bunched pairs increasing crosstalk of this, amplifying the problem. Of course the continuous series R and L and parallel C over the full lengths, which is different for different parallel pairs, could make such pulses near impossible to eliminate. Such pulses could be seen as causing a transient DC offset also.

On the subject of line tests would have thought these are more a capacitance test really, possibly with distance from exchange factored.
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Old 08-31-2012, 01:08 AM   #15
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>>>Electric fences are the hardest faults to fix, Telstra has no control over the way they are installed and maintained but must attempt to minimise the trouble they are causing. Outskirts of town everyone has a horse and an electric fence and most fences are faulty.

Maybe with long lines parallel to electric fences the induced pulses exceed the CMR abilities [slew rate limitations inclusive] of the buffer into the exchange, which would be in all bunched pairs increasing crosstalk of this, amplifying the problem. Of course the continuous series R and L and parallel C over the full lengths, which is different for different parallel pairs, could make such pulses near impossible to eliminate. Such pulses could be seen as causing a transient DC offset also.

On the subject of line tests would have thought these are more a capacitance test really, possibly with distance from exchange factored.
You just about nailed the problem with electric fences, In most exchanges the circuitry is well balanced this makes it easier to eliminate longitudinal transient clicks by making sure pairs in the cable are well balanced, modern cables are also screened.
But, In any length of cable you can bet that there will be miles of old unscreened cable still in use. There are also quite a lot of RIM installations out there that are very poorly designed and actually unbalance lines, the only way to deal with the noise is to put quite large inductors with the windings counter wound in the line.

"On the subject of line tests would have thought these are more a capacitance test really, possibly with distance from exchange factored."
No, most simple tests are DC tests looking for Insulation resistance faults. LIR to ground and foreign battery and LIR between legs of the pair. Once the type of fault is ascertained then capacitance tests and pulse echo tests are used to try and pinpoint the fault. Difficult in real life with crappy cables with multiple faults, you can be sure that most of the copper in the ground is well past its use by date. Roll on fibre to the home.
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Old 08-31-2012, 03:37 PM   #16
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Some simple trouble shooting.

Do you have another jack closer to the entry point of the shop. Try that. It will eliminate so wiring.

Did the telstra guy check it when the problem was actually occurring?
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