Intermittent Line Noise

Over the last couple of weeks, we've started getting intermittent crackling on the phone line, also causing DSL resync's.

I have a feeling that this is going to be a pain to troubleshoot as it's intermittent. Running an online line test kills the internet connection, so I never see the result, but weirdly seems to fix it for a bit.

Any ideas on how to approach this with BT, and not get a useless engineer visit that we have to pay for?

Here's an audio file of the crackling (sorry for the traffic noise in the background): http://www.filedropper.com/linenoise

Nothing changed internally etc.

Cheers,
AP

I had this once and reported it to BT as intermittent noise fault. The operator I spoke to could hear it at the time but when the engineer came it had gone. This was before the charge for no fault callouts was introduced. Engineers had to make several visits before they heard it and fixed the joint.

Not sure how you stand with the callout charges of today.

I had this on my line, every 30 mins or so the noise margin would drop to zero and cause a disconnect and resync. Turns out it was a dodgy filter

Tried another filter, phone etc. This started around the time our fibre cab (still not working) went up. I'm wondering if it's anything to do with the tie cables between the boxes?

It could be that the existing joints and wiring in the existing PCP were disturbed by it having to be opened up, to bring in the double link wires from the FTTC cabinet, although they apparently just "hang about" in the PCP until an individual subscribes to VDSL, when the PCP has to be opened again, and the necessary splitting and joining is carried out.

I have line crackles intermittently for over a year on the line I took over on moving house.

Had the BT/OR Engineer come to investigate, but sods-law intervened and he could find no problem on the day he came.

Now reluctant to try again in case I get billed £100+ for the trouble, so I live with it even though some calls are hard to hear over the crackles. Seems to be worse a day or so after heavy rain, but with no overhead wires in the area, I'm a loss for an explanation.

Fortunately, there seems to be no problem with my Infinity 2 connection.

Wish you luck...

A look in the Enta forum will show I have had exactly the same problem since my cab was wired to the adjacent fibre cab three months ago. Nightmare and can't wait for fibre switch on to get away from it. The same up here 400 miles north on our other line after fibre work. Others have suffered too.

Thanks for the replies. BT coming out today to look at it...but of course there won't be crackles when he/she turns up.

I recorded a noisy quiet line test in a bid to avoid the charge...!

Well he came, ran a bunch of tests that apparently showed there were no issues on the line.

He only heard the noise once, with the faceplate on, so started mentioning the extension wiring. Could that really be a cause, given that it's filtered with the faceplate? Would noise come back to a master socket from extension wiring?

I had unplugged all the extensions etc.

I had tried that test socket, but hadn't heard the noise to be honest - like I say, it is intermittent though.

He mentioned some AC voltage on the line, but apparently that's normal?!

Here comes the bill.....

I had an intermittent crackling on the phone line and also causing the router to reboot; this was back in October 2012 whilst still with O2. On the first engineer visit he could not find a fault as on that occasion there was no noise on the line. After O2 insisted that a second BT engineer visited, he checked all the various places such as the connection box outside the building, pole, cabinet and finally the exchange where he found a loose connection, the fault was rectified. So it is a matter of luck if the engineer you get does all the necessary diagnostics at all the places where the fault could occur! Best of luck.

I'll get shouted down by others, but in my book, the way to get this fixed is to report it as a broadband fault to your broadband ISP .... not so unreasonable considering that is what you've come here to report

An SFI engineer will understand what fault is causing the intermittent noise (an HR fault) and will have their tester in sync and be able to see the errors using the phone at the same time causes .... with this, they'll have something to chase fault wise.

Thanks for the insight Zarjaz, I think you're right, this may well be the route I need to take!

Could my extension wiring possibly be the fault? I'd disconnect it, but I have old sky multiroom boxes that need phone lines. (Grrrr) I'm trying to avoid any (further...) charges etc.

The noise comes and goes, I can hear it over the dial tone, and given the disconnects I also see, it seems quite random (middle of the night in some cases - maybe the sky boxes dialing out?).

Is it of any relevance that running a line test clears it for a while? And also, is it normal for a line test (the automated online one) to disconnect your broadband (so you never see the result!)?

Your test socket should isolate the extension wiring, give that a try.

Tried that, and didn't hear any noise, but given that it's intermittent, it's hard to say if this is eliminating the fault.

It's fine right now, so maybe they did something in the background. If it happens again I'll try without extension wiring, and if still a problem, try the BB fault route I guess.

Extension wiring is the stuff of nightmares, it basically acts as a massive aerial, pulling in interference.

The other thing you could try is an RF3 filtered faceplate, my understanding that negates the internal wiring acting as an aerial.

Next time you have the noise, how about turning off the Sky boxes and removing their power supplies from the mains sockets.

I've got the v2 faceplate, and disconnected the ring wire some time ago, so hopefully I'm as protected as I can be, whilst still having the extensions connected!

Is this known to help? I've disconnected them from the extension boxes, and no difference.

Would switching of a sky box upstairs affect a router downstairs? (The one upstairs is old, and probably close to failing!)

Just trying to get my head around how an electrical disconnection might help

A power supply should be "quiet" in an EMI (Electro-Magnetic Interference) sense. There will be noise albeit at a low level on a well designed and manufactured unit. However, it is often the case that ones designed and built cheaply or a failing PSU will create a lot of noise and that can be from Hertz right up to several MegaHertz in frequency - some will be radiated and other conducted along the attached cables. So, even if disconnected there could be transmitted EMI which a a phone line could pick up.

Thanks. Much better explained than I would have done. I just know that simply having them plugged into (live) mains can cause noise.

In reply to a post by MHC:

A power supply should be "quiet" in an EMI (Electro-Magnetic Interference) sense. There will be noise albeit at a low level on a well designed and manufactured unit. However, it is often the case that ones designed and built cheaply or a failing PSU will create a lot of noise and that can be from Hertz right up to several MegaHertz in frequency - some will be radiated and other conducted along the attached cables. So, even if disconnected there could be transmitted EMI which a a phone line could pick up.

I've heard that argument relating to other Sky boxes connected to the same LNB, but never to broadband/phone problems.

Thanks! I'll give it a try - can't hurt! Probably need to wait until the crackling is back, though may test to see if SNRM changes anyway.

Switched mode power supplies are well-known as sources of RFI noise problems.

In reply to a post by Stevenage_Neil:

In reply to a post by MHC:

A power supply should be "quiet" in an EMI (Electro-Magnetic Interference) sense. There will be noise albeit at a low level on a well designed and manufactured unit. However, it is often the case that ones designed and built cheaply or a failing PSU will create a lot of noise and that can be from Hertz right up to several MegaHertz in frequency - some will be radiated and other conducted along the attached cables. So, even if disconnected there could be transmitted EMI which a a phone line could pick up.

I've heard that argument relating to other Sky boxes connected to the same LNB, but never to broadband/phone problems.

Give me one good reason why it should not be the case with a VDSL line and modem?

We used to see a lot of it wrt ADSLx. Then Sky brought out newer/updated kit and it has largely gone away. PSUs can always gradually fail however, and the OP appears possibly to have earlier kit anyway.

It is unlikely to be the cause of his problem, but the possibility has to be eliminated .

In reply to a post by AndyPandy:

Would switching of a sky box upstairs affect a router downstairs? (The one upstairs is old, and probably close to failing!)

Possibly. There have been reports here before where a dodgy TV has effected a whole neighbourhood.

"Close to failing" - this is the type of kit that can produce lots of interference!

In reply to a post by MHC:

In reply to a post by Stevenage_Neil:

Give me one good reason why it should not be the case with a VDSL line and modem?

The Sky box transmits a 22Khz, (and if a dodgy PSU, other frequencies), signal up through a shielded cable

Edited by deleted (Wed 05-Nov-14 15:41:35)

In reply to a post by Stevenage_Neil:

In reply to a post by MHC:

In reply to a post by Stevenage_Neil:

Give me one good reason why it should not be the case with a VDSL line and modem?

The Sky box transmits a 22Khz, (and if a dodgy PSU, other frequencies), signal up through a shielded cable

And the power supply cable is shielded too? I would guess not. The PSU and Sky box are unlikely to be screened either.

In reply to a post by b4dger:

In reply to a post by AndyPandy:

Would switching of a sky box upstairs affect a router downstairs? (The one upstairs is old, and probably close to failing!)

Possibly. There have been reports here before where a dodgy TV has effected a whole neighbourhood.

"Close to failing" - this is the type of kit that can produce lots of interference!

A few years back I was seeing a company on a non-related issue and they mentioned problems with their ADSL modems resetting and rebooting "randomly". I gave them half an hour of my time ...they were in a comms room, on a shelf adjacent to a stud wall - foil backed board too. The company on the other side of the wall had a plasma TV mounted close by and when it was switched on or the channel changed it killed the ADSL signal and the modems had to resync.

In reply to a post by MHC:

I gave them half an hour of my time...

Very generous of you

In reply to a post by b4dger:

In reply to a post by MHC:

I gave them half an hour of my time...

Very generous of you

Yes it was? I normally charge them for my time in other areas.

Whilst the other guys are providing helpful info, as electrical interference can cause issues, but HIGHLY unlikely to be providing actual audible noise on the line.

Yes, you extension wiring might be causing and issue, the Sky kit will happily survive being disconnected for a while whilst you test.

Is it of any relevance that running a line test clears it for a while? And also, is it normal for a line test (the automated online one) to disconnect your broadband (so you never see the result!)?

Yes, well known for a line test to temporarily clear a minor line fault as you have. Also a line test WILL drop sync on your circuit.

Thanks Zarjaz.

If/when it comes back, I'll disconnect the extension wiring at the NTE5 and see how I fare.

Typically it's been fine all day long today! Can last weeks before it gets upset....

Looks like it's a really minor fault then. Tricky to locate.

Good luck.

To answer your specific question-

"Would noise come back to a master socket from extension wiring?"

Very definitely "Yes!"

So unfortunately, you have to remove all, then add them back one at a time, to see if you can identify the specific item - and as others have indicated, the source could be external to your phone wiring, both inside and outside your home, eg the plasma TV mentioned, etc etc etc ...

we've started getting intermittent crackling on the phone line,

eg the plasma TV mentioned,

Plasma TV's DO NOT cause audible noise on the line.

For once you have failed to champion the use of the quiet line test, whereas in this case it might prove useful.

Because the MAIN reason for my post was to answer the OP's question about how Noise etc gets propagated, which had been left unanswered:-

Tue 04-Nov-14 11:14:27

"Would noise come back to a master socket from extension wiring?"

------------

I did not "champion" or directly mention the Quiet Line Test, as the OP appears to be very aware of it, reading his postings; and I thus thought it implicit in the rest of my response:-

Tue 04-Nov-14 08:11:48

"I recorded a noisy quiet line test in a bid to avoid the charge...! "

You may consider going through your own responses in this thread, to see if you mention "QUIET line test" directly and unambiguously anywhere!

------------

I feel that the posting of comments such as yours, detracts from the best use of the site - certainly my intentions are to offer guidance to those who come on to request advice, assistance etc; and consciously strive to be constructive in my own responses.

Edited by deleted (Thu 06-Nov-14 07:42:57)

So the latest is that the line went "dead" today. I was at work, but regularly use my home PC to test "off-net" issues. The BB connection dropped, and I tried dialling home, but it just rang and rang (my answer phone didn't pick up). So, I assume dead.

I reported the fault to BT, and it was identified as a fault near the premise automatically, and the cogs started turning at BT.

A couple of hours later and it came back, according to BT, without their intervention.

Does this give any further clues on the issue? Are they likely to be linked?

Very interestingly there was a "working on behalf of openreach" van parked by my pole when I drove to work this morning....suspicious!

I had a similar problem quite a few years ago, when I was with Nildram on ADSL. The syc rate dropped right down, then took ages to recover. Sometimes got knocked back before it had fully recovered. Aften I ended up on dial-up rates of 50k or so. After 2 or 3 engineer visits the guy couldn't find a wiring fault. Even swapped me to another pair at the pole opposite. He departed saying he would have a look in the exchange. After an hour or two he phoned me back to say he wasn't too happy with the DSLAM and had swapped me to another (port?). He was a bit non-committal but it fixed the problem. I got billed by BT and it took a few indignant phone calls before they credited it back 'as a gesture of goodwill'. They never acknowledged that I should not have been billed when the fault was in a BT system.

Sorry to dig up my old thread, but the fault has been back, multiple times. They claimed they fixed it at the exchange last time, but it's back.

Any tips on getting BT to actually fix the fault?

The Indian chap I called today could hear the noise clearly, and was very helpful. I have an engineer scheduled for Tuesday, but sod's law says it'll be quiet when he/she comes!

I have a video of the noise when plugged into the test socket, with my BT phone!

Have you tried the automated line check? https://www.bt.com/consumerFaultTracking/public/faul...

Are you sure it's not the phone causing the noise?

I've done the line tests before, and they ran a couple this time.

Before the line test would clear up the noise for a bit, but not this time. The line has also gone dead for a couple of hours before.

So with that, and the fact that the BB is affected, I'm guessing that it's not the phone

As you are on "Zen Fibre 2 Unlimited"; and the fault has affected that High-Speed Broadband, suggests that the cause probably lies somewhere on your (extended) D-side line, from the FTTC via the new link to the PCP and/or from the PCP to your house and its NTE, assuming you have checked everything within the house.

What you have described sounds like a bad/high-resistance joint, occasionally going open-circuit.

If your D-side from the PCP to your house has an overhead section, it might be somewhere in that part; but of course even underground cables can suffer from bad joints.

Handy having the video.

If you have to report it again and there is noise during the reporting call, might be worth recording that.

I have an engineer scheduled for Tuesday, but sod's law says it'll be quiet when he/she comes!

When they do come, it is likely to be on a CDTA task (conscious decision to appoint) The very first thing they should do, apart from having a listen, is to make an end to end pair quality test from the NTE with all else unplugged. This will be done with their hand held tester, either a JDSU or an EXFO.

Show a little 'keenness' in what the are doing, "Do you mind if I watch ?" that kind of thing. Watch the results come in on the tester, you'd ideally be looking for 100 or 99% cap balance, and AC balance of 60db or above, and no more than 5 ohms difference (the less the difference the better) between the leg resistances. Ask the engineer to explain all the results as they come, especially if any of them come in with an exclamation mark beside them.

Good luck, hope you get a decent cove !

Thanks Zarjaz, I'll try and get a look at what's going on, if the engineer is friendly!

I haven't touched anything this time, in an attempt to keep the noise there ready for tomorrow.

I'd thought about taking the filter off an going into the test socket, but as I removed all extension wiring after the last time, I figured that it's not worthwhile.

It's worth mentioning that the BB stays connected (mainly) when it's noisy, but then using the phone will almost always cause it to cut out. Perhaps a clue in that?

Cheers,
AP

And would you believe it, a *very* good engineer turned up, and was ready and willing to climb poles and all sorts.

The noise was there, and in the test socket, but all the tests came back perfect....! Perhaps those test units should have microphones

Anyway, he then went on to test the bare wires coming into the house...and no noise! So a new NTE5 front fitted and it seems that all is now OK!

I was hoping my attainable on the fibre might go up to where it used to be, but it hasn't, so crosstalk must be causing that.

We talked about vectoring, and they're getting training on it now, as a vectored line can fail an insulation test apparently.

Happy puppy today!

Let us hope that's an end to it .........

as a vectored line can fail an insulation test apparently.

At present, the only cards with vectoring on them are (I believe) the third gen Huwawai ones, there is a known issue where an end to end pair quality test will show an earth contact on both legs/low insulation. Not a fault, just a PITA.

Not a fault, just a PITA.

That's how this chap explained it, it'll flag as a fault, when there isn't one )

Finger & toes crossed that this is the end to my woes!