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[sqwim]

Good site, lots of useful info.

I'm with Tiscali (I pay line rental to Tiscali too, not BT) , have a Netgear DG834G v3 and a problem with noise.  I'm wanting to find out how much fluctuation in the downstream noise margin is acceptable and what might be considered a line fault.

I'm using the master socket, I've checked the filters, I've checked the cable, I've tried the latest (and the not so latest ) firmware for the router.  I've tried a different Netgear DG834G router.  None have fixed the issue.

My usual line stats are:

                                                Down                                       Up
Connection speed:                   5200 kbps - 6200kps ish         448 kbps
Line Attenuation:                     43 db                                       12 db
Noise margin:                          ?? db (see below)                    22 db

The ?? is the problem.  I've used RouterStats to log the stats over a number of weeks now and all the other stats remain resolutely static come what may but the downstream noise margin can fluctuate widely.  During the day (weekday or weekend) it will typically remain fairly consistent between about 12 + 6 db until usually around 7-9pm at which point it will fluctuate far more, eventually hitting 0 at which point the router will usually drop the connection and the the noise margin will stick at something like -214000000 (this seems to be a known problem with the Netgear DG834G routers - I don't think the issue is the router(s) though, I just think the noise margin should never get that low!).  It doesn't matter what connection speed I have, this happens even with the lower connection speeds.

I'm assuming this is a problem with noise on the line at these times of the day, pretty much always in the evening.  What I'd like to know is how much noise margin fluctuation is acceptable (I appreciate I have to expect some) before this is considered a line fault and I can reliably get an engineer out to fix without risking them charging me as they will come during the day when the problem doesn't happen?!  Is this something I should take up with my line provider, Tiscali?  How likely are they to actually fix it?  I assume there are some spare pairs available, but would this fix it?
I attach a few examples of the issue, showing a relatively consistent noise margin starting to fluctuate and cause problems.  I'd appreciate any advice.  

Thanks
Sqwim

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[roseway]

Hi and welcome

No, that's not normal. It looks like an intermittent line fault (high resistance fault) probably, although it could be electrical interference from some possibly malfunctioning equipment.

There's a lot of general advice on noise problems here but in the first instance there are a couple of simple things you can check:

1. When the noise margin graph is fluctuating wildly, can you hear any crackles or hiss on the phone? If so this would tend to confirm the theory that it's a line fault. You should report it to your phone provider as a voice fault. With BT you would dial 151 to do this, but I'm not sure if that number still applies when you pay the line rental to another company.

2. If you have a normal NTE5 master socket (see the link I mentioned above) you can connect your router and a phone via a microfilter to the test socket. This eliminates extension wiring from the connection, just to make sure that the problem isn't due to a fault in your internal wiring.

[jid]

but I'm not sure if that number still applies when you pay the line rental to another company.

Following on to Eric's post, you need to report this to Tiscali Talk on 0871 222 3311.

With previous experience of Telephone outages they tend to fix them within 24hours.

If you have any crackling on the line as Eric says report it immediately to the number above.

Let us know how you get on

[GunJack]

This is not normal.....I'm on Tiscali LLU and am having similar issues....posted here:-

http://www.dslzoneuk.net/forum/viewtopic.php?f=25&t=17306&sid=ed2f96253b9fea446f20ca55c27a8198&start=0

and 'coz it's intermittent, it's turning into a bit of a saga


p.s. that's nothing against the guys on this site, it was just I was on there when I felt like ranting.......

[sqwim]

Firstly, thanks for the replies folks.

I have been connected to nothing but the test socket behind the master telephone socket for the last 3 months whilst investigating this issue and have exactly the same problem as when I am not, so can rule out out the house wiring. 

I have not been able to discern any crackles or hisses on the phone line when the problem occurs.  It sounds, to my ears, just like it does when the problem is not occurring.  What's the best way to conduct a quiet line test?  Advice I have seen seems to indicate dialling 17070 and then option 2 but all I get is a computer confirming the line number and then hanging up.

I've tested absolutely every electrical device in the house that we might use during the evening (when the problem occurs) and not one has any effect on the noise stats.  If it's looking like the problem might REIN related and is out of my control (street lighting for example), what's my best bet moving forwards?  I assume Tiscali are unlikely to have any sway in getting the council to change their lights?!  Can they change the connection to see if I get exactly the same problem with a different pair, thus confirming REIN?  Would they charge me for that or do I stand a chance of them doing this to assist my investigations?

Is an NTE5 ADSL faceplate likely to deal with / filter the noise better than the micro filters I'm currently using which came with the various broadband installations I've had over the years (even though the problem does not appear to be with the house wiring)?  If it is, does anyone have any advice on which the best ADSL faceplate is?

Thanks again
Sqwim

[sqwim]

Having thought about this, and in addition to the questions in my last post, I'm after a point of clarification about REIN.

Does the interference affect my router, the line delivering ADSL to my house or both?  Some advice seems to indicate that it's my router it's affecting which means, I assume, that I should be able to shield it in some way (yes, that probably wouldn't help with my wireless connection!).  Is this the case?  Or is it just as (or more) likely to be affecting the phone line itself?

Sorry, questions, questions!

[jeffbb]

Hi
quote  (I pay line rental to Tiscali too, not BT) ,

That is probably the reason you don't manage to do quiet line test . Check with tiscali to see if they have a number .

Regards Jeff

[roseway]

Having thought about this, and in addition to the questions in my last post, I'm after a point of clarification about REIN.

Does the interference affect my router, the line delivering ADSL to my house or both?  Some advice seems to indicate that it's my router it's affecting which means, I assume, that I should be able to shield it in some way (yes, that probably wouldn't help with my wireless connection!).  Is this the case?  Or is it just as (or more) likely to be affecting the phone line itself?

Sorry, questions, questions!

REIN is electrical impulse noise which can be picked up anywhere between the exchange and you. It could be picked up directly by the router, but I would say that's the least likely possibility. Far more likely is that it's picked up by wiring, either your own extension wiring, or the incoming phone cable.

[sqwim]

Well, I've finally reported it to Tiscali so we'll see what they make of it (and how they handle it, I've got past the first 'follow the script' stage and they've escalated it to Tier 2).

Interestingly, today (Saturday) the noise margin was pretty steady betweeb 8-10 db from 10:00 till 16:34 when there was a sudden drop to 3db where it remained until 17:21 when it dropped to 0 and the router was restarted.  However, following the restart it has been steady at 8-10 db again.  Why would that happen?  Why would a router restart 'reset' the noise margin straight back to a steady 10 db when previously it was at 3 db (until it hit 0)?

So to today's noise margin summary:

10:00 - 16:34  - 8-10 db
16:34 - 17:21  - 3-4 db
17:21  - 0 db and router restarted
17:23 - 18:34  - 8-10 db
18:34 onwards  - started wildly fluctuating, will do so until the morning (7-8am ish) hitting 0 numerous times.

Cheers

Sqwim

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[jeffbb]

Hi

quote  Why would a router restart 'reset' the noise margin straight back to a steady 10 db when previously it was at 3 db (until it hit 0)?

If it lost synch then the router renegotiates with the DSLAM using your Target SNR .Usually with a loss of synch speed ,if the noise that caused the resynch is present . If the problem has cleared then it will resynch at similar speed .
Regards Jeff

[geep]

Hi,
Your examples are somewhat similar to my own experience with a DG834v2 which like your v3 has a TI chipset.
In June I changed to an ST546 with a Broadcom chipset, and this reduced the wildest excursions, although my SNR Margin is still pretty wild.

I've been logging SNR Margin since January here: http://pgg999.co.uk/stats/st546.html
If you take a look at June, the first half of the month with the TI chipset is a bit like your logs. The second half is quieter using the Broadcom chipset.

This comparison might also be of interest: http://www.vwlowen.co.uk/misc/routers/compare.htm

Cheers,
Peter

PS - In the last week discovered that some step changes of > 3dB in SNR Margin were due to my son's PC
being switched on or off. Installing a new PSU fixed the problem.

[sqwim]

Thanks for the replies, I may well have to investigate a more tolerant router.  It just seems a pity as that router on other lines I've tested it on definitely does not have a problem - the SNR would remain rock steady with 2-3 db variance over 3 days of continuous testing.

On my line however, it's a completely different matter.  I have been in contact with Tiscali support who eventually tried setting the SNR to 17 (and thus my bandwidth down to <2Mb!) to test - the fluctuations ranged from 26db down to 1db - a 25db range!  Again, the problem seems to be mainly between 7pm & 7am, although I do get severe SNR drops down to close to the problem 0db during the day from time to time also.

I explained that I'm not happy with 2Mb bandwidth and that even with that high SNR setting it will, soon enough, hit 0db and cause the problem (it had already got as low as 1db).  They've put me on an 'Adaptive1' profile to test for 48 hours but it's just as bad as the 'Standard' profile, the SNR varies wildly and eventually affects the router.

Tiscali have been pretty rubbish really, their support representatives speak heavily accented English over a pretty poor line (their end) and seem insistent on telling me that 'SNR doesn't matter, it can even go negative, as long as there is a connection'.   Should I really have to put up with a line that has a 25db variance in SNR?

Anyone have any tips on how to get Tiscali to actually investigate / fix this?

Thanks

[jeffbb]

Hi
quote Anyone have any tips on how to get Tiscali to actually investigate / fix this?



The only way is to escalate to their TOP guys .Tiscali have (had) a 3rd level of help UK based . They were clued up and helpful .

this was the guy in charge ,but may not be there now . Richard.Lawrence@uk.tiscali.com

[sqwim]

So it is reasonable to expect a line which does not have a 25db fluctuation and I should complain further on the grounds that the fluctuations mean 0db is reached on a regular basis which causes problems with the router?

What would an acceptable fluctuation range be?

Thanks

[jeffbb]

hi
quote  What would an acceptable fluctuation range be?

Its a bit like asking "how long is a piece of string".
In an ideal world no variation. In the real world then the norm MIGHT be that the SNR margin would gradually drop as more noise comes on line say during evenings during busy periods that change may be 3 to 4db . It should not be so large and rapid as to cause loss of synch. You would not expect large spikes  (REIN).The problem is how to find the cause .I have a similar pattern to yours the main thing is that the steps are about 3db max  . see below
the first one covers most of a day ,the second is the last 4HRS showing a gradual decline .

I have a target margin because of a problem a few months ago . So  a 3 to 4db drop does not affect me . Your steps are much more extreme . You seem to have 2 conditions  a definite step that drops your SNR margin that suggests something switching  and a very spiky trace that looks like some general noise REIN ?

Sorry can't be specific as to what is acceptable .
Regards Jeff



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