Crazy noise margin

[Rik]

My noise margin went a little loopy at 12:09, dropping to -5db, which forced a re-sync at 1480kbps. I promptly re-booted the router and got back to 3424 for 17 minutes before sync dropped again and I ended up at 3328. Finally, sync went again at 14:09, and I settled at 2752, but with a noise margin of 10db.

You can see the first drop below. This is not the first time when the line has been stable for days, even weeks, and has suddenly been hit by massive noise spikes, so I gave Miriam a buzz to see if she had any ideas. She's been seeing the same thing all over the country, but with no apparent pattern. It does seem to happen, though, at exchanges where there are LLU operators. Possibly, then, the cause is these guys going in to work on their equipment and not being terribly careful while they are there.

Curious, but if you see something like this, it would be interesting to know if your exchange has been unbundled.


[attachment deleted by admin]

[DorsetBoy]

Well there you have it Rik,that is the pattern I had for 12 days or more and BT say "not us,nothing wrong".

Suddenly after the engineer comes,it all stops and I get the best performance I have ever seen until today at ,yes ,12.10 whack I get a huge leap in SNR and my synch and profile are ruined again.

Still riding at 11+ db ,was 9>6 yesterday.

BT have some explaining to do,they can't keep fobbing everyone off like this.

[Rik]

Interesting that it was 12:09 for me, 12:10 for you Dorset. Those times are too close to be mere coincidence.

Shame we don't have a tame BT engineer here who might be prepared to say if there's anything scheduled for that time slot.

[DorsetBoy]

Rik ,they know darn well what is going on but will not say anything.

[jupiter]

I used at times to get that kind of pattern when I was on 1Mb fixed speed (long line at 57db attenuation), but it was a Netgear DG834 which does display odd SNR readings at times.  I did the usual wiring improvements (as described in the sticky  at the top of this board) and that helped but did not eliminate the behaviour.

I was therefore quite nervous of going to Max, fearing that I would get lots of profile hits through re-syncs.  In the event, over several months, this has not happened (currently on 10 days without a resync) and the profile has usually been either 2000 or 2500, a satisfying improvement on the previous fixed speed.

I am on a comparatively small exchange with no LLU operators, nor likely to have them.  In common with hosts of others the exchange status is red, as it has been for over 6 months.  But I suppose it may be that those on larger exchanges may suffer more unexplained hitches because there will be more going on at those exchanges in terms of various fingers in the pie.

[Rik]

I suppose it may be that those on larger exchanges may suffer more unexplained hitches because there will be more going on at those exchanges in terms of various fingers in the pie.

That's my growing suspicion, Jupiter. I'm used to the Netgear 'wobbles', but they usually don't cause the line to drop, just show odd figures. This was clearly a series of huge spikes, enough to halve my normal sync speed. Now, if a Be or Tiscali engineer is poking around in the exchange, say, he might not be too bothered about BT's equipment? I doubt we'll ever know for sure.

[Glenn]

No problems seen here, my connection has been up for 14 days without dropping a connection.

[Rik]

You're just trying to make me jealous, aren't you?

[Rik]

Rik ,they know darn well what is going on but will not say anything.

That's the problem, isn't it? We need inside information...

[DorsetBoy]

Well they will be getting an earbashing next week thats for sure.

36 hours of perfect stable line and its all gonre to pot again,SNR is leaping from 6db to 23db and back

[Rik]

For that to be happening, it has to be an exchange or line fault. Once you're 'inside' the system, nothing should be affecting your stats. I wonder whether it would be worth asking Miriam to move you to fixed rate and then back again. That 'shuffle' would mean that your exchange connection was changed around, and so eliminate that end of the line.

[DorsetBoy]

Well they insisted that there was no fault on Thursday,yet 25 minutes after the engineer is gone all the activity ceased and my synch is up to 448/8128.

No problems at all until 12.10 on friday 13th and since then the synch has gone down twice.
It is no coincidence that others are having the same thing happen and it is clear that BT/line/exchange are at fault.
This line has been stable and synched at 448/8096 for over 12 months and as the BTW guy said "There is nothing wrong with your equipment or installation".

[Rik]

"There is nothing wrong with your equipment or installation".

Be nice if he'd say what the problem is, rather than what it isn't.

[psp83]

BT is the problem!

Sorry but through out the years i've had nothing but trouble from BT and i hate them

[Rik]

I can understand that, we are effectively held to ransom by the company. It really requires a change of thinking from the Govt. There should be a national policy to create a telecomms infrastructure to the highest standard. It should not be based upon one company's financial ability and need for profit. If we ran the roads the way we run telecomms, can you imagine the mess?

[rireed3]

I have had three similar experiences.  My exchange has LLUs.

In January I got two weeks of horrific noise, so re-graded to 2 M.  After a week of charting these attacks, I sent in the charts and Miriam contacted BT.  "Nuthin' to do with us."  Noise went away completely within hours, I went back to 8 M the next week, no more noise for a month.

Noise came back one Saturday in early March (week-end of a VP upgrade).  Made a 151 call during the audible noise.  "Nuthin' to do with us".  Noise went away then and has not come back.

Had increasing trouble with "continuous dial tone" (can't dial because it doesn't stop).  Made a 151 call, "Line checks out", two different phones in the test socket, they insisted on scheduling a visit when I persisted with the fault.  I scheduled the visit 4 days away, so I could see if they fixed it.  They did!   

I cancelled the visit 36 hours before, after two days of no dialing troubles.  No trouble since.

This behaviour is designed to satisfy some sort of metrics their idiot management have instituted, so rather than reflecting what's actually happening, it looks like they are catching problems before they become apparent, or they can charge us if they fail to find the problem!

Richard

[Rik]

I know how you feel, Richard. I've had a strong sense of late that BT don't/won't admit to faults, but then quietly fix them. It seems to be happening too much to too many people for it to be coincidence.