Unresolved support ticket open for more than six months - is this a record?

[#1]

I'm feeling a bit overwhelmed with all the replies - it'll take me a while to catch up. But do I appreciate all the suggestions that have been made as well as all the time and effort people are devoting to helping resolve this problem.
OK, I've spent some time trying a slightly different tack i.e. switch off all the power at the mains and then use the AM radio to see if the interference noted last night changes. Well, the interference diminished or disappeared altogether for all frequencies except that at around 600 kHz. I tried wandering around the house and immediately outside and it was pretty much the same. The power was off for about 45 minutes whilst I did various checks. When I powered up the system and checked Routerstats and DMT I found that the sync rate had increased to 2912kbps with a noise margin of about 20Db. Actual download speed was still pretty poor (at around 100kbps) but that's probably because the IP profile took a hit after yesterday's trip into the abyss. Latest graphs are attached.
I also rechecked the interference with the AM radio and found that this was pretty much the same as last night, with most of it localised around the pc equipment. The signal strength of the interference is not great i.e. by comparison with a radio broadcast it's pretty low. For example, if I tune into a strong UK radio signal and then turn the volume down until it's just strong enough for me to make out all the words being spoken, and then tune into one of the interference frequencies then I can barely hear any pattern at all. Also, most of the interference frequencies I mentioned last night are fairly localised around the pc equipment and I suspect that the pc, LCD monitor, router etc are all emitting noise at different frequencies - does anyone know what these might be or is it likely to vary by manufacturer, model etc? The "morse code" signal (around 790kHz) is mainly "dots" with a few "dashes" and, somewhat bizarrely, is louder in the bathroom (which is next to the study where I have my pc)....
But, the question that keeps coming back to me is why do I have noise margin variations and line disconnections when all this pc equipment (apart from the router) is switched off? e.g. when I'm at work. This is what happened on Friday when the DMT graph was shot to pieces. I'm no expert in anything electronic or electrical, but I'm inclined to discount everything except the router as this is the only thing that's switched on when problems arise during the working day. A few people have suggested changing the router, but I've done this several times in the past (alternating the Netgear DG834 with the Draytek 2600G), but I'd prefer to leave the Netgear in place for now as it is giving me additional diagnostic info. These two routers, by the way, use different PSUs and both have suffered similar disconnections and noise margin variations so I'm inclined to discount these as the culprits as well. Another suggestion was to try a USB modem and I did try a Zoom USB modem before Christmas but that made no difference to the line performance either.
And a few specific answers:-

Quote from: Axis

Have you tried fitting an i-plate or disconnecting the bell wire?

Yes, BT have fitted a new master socket (twice!) and fitted a new filtered faceplate (aka SSFP - Service Specific Face Plate). The bell wire is not connected.

Quote from: xpcomputers

Did the earth problem get fully sorted yet? Or is that still waiting the electrician to do the next phase?

An electrician is coming on Wednesday to fit a new consumer unit, so that should eliminate any possibility of poor earthing being the culprit. But the elecrician seemed confident that the existing earthing was ok.

Quote from: xpcomputers

What if there is someone trapped in the exchange and sending morse code in an attempt to be rescued?

They're probably BT engineers locked in by unhappy customers 

Quote from: xpcomputers

Could you even record the sound from the radio onto the computer,

Unfortunately not - I don't have any means of recording this.

[#2]

That noise margin graph is amazing, given the steady sync speed! 
I guess you just have to keep plugging away at BT via PlusNet, presumably waiting until at least Monday.

[#3]

Yes, it looks as if I'll have to wait until Monday as PN support haven't been in touch since yesterday morning. Might need @orbrey to give 'em another nudge...

[#4]

Quote from: Catweazle

I'm feeling a bit overwhelmed with all the replies - it'll take me a while to catch up. But do I appreciate all the suggestions that have been made as well as all the time and effort people are devoting to helping resolve this problem.

I can understand that - but some of us like a challange  - sorry if we drift slightly off topic occasionally.

Quote

OK, I've spent some time trying a slightly different tack i.e. switch off all the power at the mains and then use the AM radio to see if the interference noted last night changes.

I'm just wondering if there is a poor connection in the ring main that you use for the router. Sorry I forget how old the property and more importantly the electrical installation is - have we suggested getting an electrical inspection done ?. maybe worth it if wiring is not that new ?.
PC's are very noisy - if you put a receiver anywhere near them they can block all Medium wave/short wave signals. But of course with the wired routers, this isn't normally a problem.

[#5]

Quote from: mal0z

I'm just wondering if there is a poor connection in the ring main that you use for the router. Sorry I forget how old the property and more importantly the electrical installation is - have we suggested getting an electrical inspection done ?. maybe worth it if wiring is not that new ?.

I'll see if the electrician can provide an opinion on Wednesday when he fits the new consumer unit. The wiring seems to be c. late '70s or early '80s, but I'll check this with Sparky as well.

[#6]

Oh well - that's great - He will probably have to do insulation / continuity checks on all the rings and light circuits anyway then as he will have to disconnect the old box and put on new .
Maybe best we wait until after that...........
Fingers crossed 

[#7]

If I read it right, the interference was not present when the power was off - I would be interested to know if you could isolate which item was generating the interference by unplugging each item, one at a time, from the wall.
Do you have an LCD monitor that has an external power supply, for example?  Turning product like this off will usually leave a live circuit inside the PSU (same for a PC) so if there is a faulty component this might be causing RF bleed.  This would also explain why it happens when your equipment is powered off (unless you do power everything off at the wall socket ofc)
B.

[#8]

All the pc equipment except the router is plugged into a Belkin trailing socket and I power this off at the mains overnight or when I'm at work during the week. The ADSL and LAN cables aren't routed through the Belkin board, though i.e. it's a clean connection from router to master socket and router to pc.
The router is plugged into a separate mains socket and is switched on 24x7.

[#9]

Had another blip at 15:13 today - Rx noise margin went from 3.8Db to 17.3 and then back down to 9.4. Sync rate dropped from 2912 to 1472. Even line attenuation changed - from 26Db to 44Db. Tx noise also dropped from 17 to 7, and sync changed from 448 to 320 - this is unusual as Tx noise/sync stays pretty constant normally. A side-effect was that I couldn't connect to any websites at all, so I rebooted the router at 15:33. Rx sync went up to 2848 and noise started at 14.9, went up to around 20Db for 10 minutes, before dropping to about 10Db. Tx sync is back to normal i.e. 448kbps. Actual download speed is still crawling along at around 130kbps. Here are the latest BT speed test results (as at 16:01 today):-
Test1 comprises of Best Effort Test:  -provides background information.
    Your DSL connection rate: 2848 kbps(DOWN-STREAM),  448 kbps(UP-STREAM)
    IP profile for your line is - 135 kbps
    Actual IP throughput achieved during the test was - 82 kbps
Didn't notice anything odd going on at the time (15:13), so another one to add to the X-file for PN support (whom I'm now referring to this discussion as I can't add any more docs to the support ticket!). Routerstats and DMT graphs are attached - three DMT graphs show the line performance before the blip, after the blip, and after the reboot.

[#10]

Quote from: Catweazle

somewhat bizarrely, is louder in the bathroom (which is next to the study where I have my pc)....

That to me is the oddest bit. It would suggest that the noise might nit be round the PC at all... do you have heating in the bathroom? Hot Water Cylinder? Electric Toothbrush Charger?  I'd want to find the culprit in the bathroom, by trying the radio in every corner and nook of the bathroom, in case your source in is there!
Does you phone line pass through the bathroom?

Quote from: Catweazle

why do I have noise margin variations and line disconnections when all this pc equipment (apart from the router) is switched off?

When you say it is turned off, do you mean unplugged/switched off from the wall, or just turned off on the unit? Most power supplies are still working until they are switched off at the wall, and I've known them to become "noisier" when not turned on... (of course some get quieter, so no fixed rules!). If you don't unplug/switch off from the wall, then I would try doing that... but equally, I wonder if your problem might be in the bathroom... and the PC just a red herring....
Mike

[#11]

Quote from: Catweazle

Had another blip at 15:13 today - Routerstats and DMT graphs are attached.

My interpretaion of that is:
1. Running along quietly with little noise....
2. Noise starts, pushing your marging down (to about 4?) a level which is a bit dangerous
3. After a while the link finally gives up and resyncs at a lower speed (due to noise) - looks like 9dN target SNRM
4. The noise stops BUT at the "switch-off" there must have been another brief burst of noise as it resyncs and not at an ideal rate.

[#12]

Quote from: HPsauce

My interpretation of that is: 1. Running along quietly with little noise.... 2. Noise starts, pushing your marging down (to about 4?) a level which is a bit dangerous 3. After a while the link finally gives up and resyncs at a lower speed (due to noise) - looks like 9dN target SNRM 4. The noise stops BUT at the "switch-off" there must have been another brief burst of noise as it resyncs and not at an ideal rate.

I would concur with that, except I'd also say that at step 1 the modem was running along with little noise, but a high SNRM because of previous noise.
At 14:11, where the noise starts, the drop from 20 dB to 4dB says that the modem can kinda cope at that level. However, the DMT image of 14:24 shows a block of 120 CRC errors in the preceding 15 minutes, alongside 2 errored seconds - so there was sufficient noise to throw things very temporarily.
The DMT graph of 15:24 shows nearly 1000 CRC errors in the preceding 15 minutes, alongside 10 errored seconds - presumably at the point the signal was dropped at 15:13. However, it also shows no CRC errors in the 45 minutes before that - indicating that the modem coped well at that 4dB level for the majority of the time.
I think the noise & sync graphs show that the noise continued after the resync at 15:13 (the decreased sync rate and the partial increase in SNRM countering each other). And if I'm right about that, then the noise would seem to disappear at around 15:33 (as we're almost back to the same SNRM and Sync speeds as we started with). But Catweazle indicated that the router was rebooted at 15:33, so I'd then have to ask whether the 2 events of the router reboot and the noise stopping were linked. However, I know we've tried with a different router.
If I'm wrong with that last bit, and the noise actually stopped around 15:13, then the noise profile would seem to show that the overall noise lasted from 14:11 to 15:13; it has a sharp turn-on, and sharp-turn off, but the modem copes with the noise for almost all this time. However, there are bursts of CRC errors at the turn-on and turn-off points. That kind of profile would make me suspect something *else* being turned on, and perhaps with an inductive load like a motor (more like a central heating pump or valve, rather than fridge or freezer) or fluorescent lights.
If you got noise in the bathroom, is that also near any of the heating control system?
I should say that I get similar step changes in my noise levels, but not to a degree that affects throughput. I haven't worked out what causes them either.
One thing on the graphs that I am confused over though: The yellow bars on the 1st and 3rd DMT graphs. The 2 graphs are taken with roughly the same sync rate (and the blue bars look roughly similar), but the the SNRM is vastly different at these 2 times. I'd expect there to be a difference in the height of more of the yellow bars. I think...
Mike

[#13]

And another blip at 20:43 last night - looked like a disconnection but the IP address didn't change (I wasn't using the pc at the time, so didn't see whether the connection stalled). Routerstats has been running 24x7 since Friday night, so there's loads of evidence in the log files should anyone in PN support or BT be interested. Sync rate is now 224kbps and noise margin is 31.8Db. Line attenuation is 26Db. Actual download speed is still around 130kbps.
There was also quite a bit of noise margin variation between 16:36 and 17:50, but this didn't affect the sync rate (it stayed constant at 2848kbps until 20:43, so I didn't attach the sync rate graph for this period.
I'm hoping that PN support can now get back to BT and get them ticking more items from their list...

Quote from: xpcomputers

... do you have heating in the bathroom? Hot Water Cylinder? Electric Toothbrush Charger?  I'd want to find the culprit in the bathroom, by trying the radio in every corner and nook of the bathroom, in case your source in is there!

No, nothing in there apart from electric towel rail (switched off at the mains) and electric shower - neither showed any signs of being the source of interference when checked with the AM radio. The phone line doesn't pass over the bathroom either - it runs through the outside wall of the study and then back through the roof over the study. When I said "bizarrely", that was quite accurate - the "morse code" noise at 790kHz gets louder near the WC. 

Quote from: xpcomputers

When you say it is turned off, do you mean unplugged/switched off from the wall, or just turned off on the unit?

Quote from: Catweazle

All the pc equipment except the router is plugged into a Belkin trailing socket and I power this off at the mains overnight or when I'm at work during the week. The ADSL and LAN cables aren't routed through the Belkin board, though i.e. it's a clean connection from router to master socket and router to pc. The router is plugged into a separate mains socket and is switched on 24x7.

Quote from: WWWombat

That kind of profile would make me suspect something *else* being turned on, and perhaps with an inductive load like a motor (more like a central heating pump or valve, rather than fridge or freezer) or fluorescent lights.

The only electrical equipment that switches on and off regularly is the gas central heating (combi boiler, so no hot water cylinder), fridge, and freezer. I've tried leaving the fridge and freezer off for about 30-40 minutes and that makes no difference - no blips when I switch them back on either. The central heating is on a timer, but I can hear it coming on and that doesn't correspond to any of the info on the graphs. I've also monitored Routerstats when the hot water is switched on as the boiler will kick in at that time but, again, no problems that I can see.
I still suspect the BT infrastructure, so let's hope PN support can get BT to take further action.

[#14]

One final recommendation from me, to keep you "ticking over" while the wheels grinds slowly into motion....
Unless advised otherwise by PN/BT if you see a situation where the speed is stupidly low (below 1 meg say) but the SNRM is high (over 15 say) and has been that way for a while (5 mins maybe) I'd resync to get a better speed.
If that DOESN'T get a better speed it points very strongly at your modem/router or the exchange port.

[#15]

Quote from: Catweazle

When I said "bizarrely", that was quite accurate - the "morse code" noise at 790kHz gets louder near the WC.

You mean as it gets closer to the copper cold water pipe which fills the cistern. Would this be because the pipe is acting as an aerial and amplifying the signal?