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Author Topic: Very high noise margin drop in afternoon  (Read 64063 times)

MikeS

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Re: Very high noise margin drop in afternoon
« Reply #15 on: January 11, 2008, 01:11:17 PM »

Hi Azzaka

It is encouraging that you may be getting to the stage of updating AR7 code to resolve the current issues.  Is this likely to be able to be applied to all AR7 routers or only to the Netgear ones ?.  - for instance the SAR 600EH that I have.

I've got an engineer coming this afternoon to have a look at my line.  Hopefully he will be able to find something to fix.  If not then I'm stuck with buying another router, which I'm reluctant to do having only recently bought the SAR which has the advantage of hanging on down to -3dB or so.  Also I feel that my line is flaky and is a contributory factor to my problem, if that is not fixed then another router may not fix the issue.   However I may have no choice. 
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kitz

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Re: Very high noise margin drop in afternoon
« Reply #16 on: January 11, 2008, 01:22:31 PM »

Hi Ezzer and welcome to the forums.

Excellent post.  In actual fact I did start something on this a few months back but never got around to completing the page. :/
(Anyone who knows me, knows there is tons of stuff I want to put up and its always an ongoing task).
Rather than re-invent the wheel, Ive "slotted" your post in the middle of something else and given you credit for the applicable bits,
that way at least it gets published today - rather than being sat in my "to dos" :D

REIN faults
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kitz

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Re: Very high noise margin drop in afternoon
« Reply #17 on: January 11, 2008, 01:37:58 PM »

>> however what i was suggesting is not a REIN issue.

Possibly this thread has got confused with 2 lines of thoughts. I think Ezzer was responding to Mikes orginal post which could well suggest a possible REIN fault.

>> i am sure there is a lot of people who read these forums that do and will appreciate your good and accurate explanation with regards to REIN and DSL connections. This is something we seldom receive in a lot of cases.

It is something that does crop on on occasions therefore my reasoning that it does deserve a mention on the main site.
Most zen users by nature are more adept at tracking down their own faults, therefore may pick this sort of thing up before even approaching the ISP.
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kitz

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Re: Very high noise margin drop in afternoon
« Reply #18 on: January 11, 2008, 01:39:57 PM »

>> I've got an engineer coming this afternoon to have a look at my line. 

Good luck mike - remember to show him the logs showing what happens, and also ensure that you mention you have tried a couple of different routers which also display the same symptoms.

Let us know how it goes.
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Azzaka

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Re: Very high noise margin drop in afternoon
« Reply #19 on: January 11, 2008, 02:36:44 PM »

Unfortunately it is only the Netgears at this stage, however I will be contacting another company next week as one of their customers was told that a certain firmware would fix the fault, which it hasn't.

I will let you all know how it goes. And we all ask that you do the same.
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #20 on: January 11, 2008, 06:54:51 PM »

Well the engineer has been and gone.  Showed him the routerstat graphs with the three o'clock drop off.  Said he hadn't seen anything like that before, but the lines locally were crap.  He felt that as the line appeared OK until 3 ish that it wasn't a cabling issue.  So he thought it worth trying a lift and shift, which he went away and did.  He came back and checked sync/errors with his modem (non AR7 I assume) and sync'd at 2600 with virtually no errors.  We then connected through my (AR7) SAR600EH and sync'd at 4100 at a 6dB noise margin.  I have never seen a sync this high, normally I sync at 2200-2400 with a 15 dB noise margin. However I read somewhere that you loose about 600-700k of sync speed for every 3dB of noise margin increase, so I guess that the two situations are equivalent. When lift and shift occurs does this reset the target noise margin to the 6dB standard, or am I in a retraining mode ?.  Currently at -4dB, so it hasn't cured the noise margin movement time will tell if it any more stable in practice.  Sync has just dropped to 3700, noise up to a giddy 2dB.

What surprised me talking to the guy was that they don't have a list of what previous engineers have done in trying to fix the issue.  He was asking me what the others had done.  They do have a list when its a telephone fault.  Seems an odd way of going about it, bearing in mind that broadband faults seem to be a bit of a black art, with a lot of suck it and see, also leaves the possibility of engineers swopping pairs backwards and forwards.  He also said they have two hours to fix the issue, then essentially they walk away.

He mentioned REIN but said this was a specialist issue and was not something that they could deal with.  The other option he suggested was to switch to a 2Meg fixed line, which he felt would be more stable. 

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kitz

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Re: Very high noise margin drop in afternoon
« Reply #21 on: January 12, 2008, 02:26:08 AM »

>> He felt that as the line appeared OK until 3 ish that it wasn't a cabling issue.

I think I'd agree with that.


>> I have never seen a sync this high, normally I sync at 2200-2400 with a 15 dB noise margin.

Although Im not 100% certain, it does indeed seem like the lift and shift has probably put you back in "retraining".
Like you say the sync speed and SNR figures are relevant and will affect each other.

>> Currently at -4dB, so it hasn't cured the noise margin movement time will tell if it any more stable in practice.

:/
Possibly on a bit better line, but the huge variation in your SNR Margins would seem to indicate that something is still there which is causing interference. 

The DLM will need time to adjust and increase your target SNR ..  which will decrease the maximum speed which you can sync at.  Its possibly too early to tell, but from your observations so far.. whilst I hate to say it, it doesnt seem to have cleared the fault.  Did your graph dip in the same manner as previous days?

>> Seems an odd way of going about it,

Indeed - I would have thought they must have notes somewhere?

>> He mentioned REIN but said this was a specialist issue and was not something that they could deal with.

They being BT? or within his particular job description?   Sometimes issues are passed on to SFI who may attempt to do something.  It all seems to depend on the engineer pressing this further based on where he feels the fault may be coming from. If they feel its in the home then this is certainly outside their remit.

>> The other option he suggested was to switch to a 2Meg fixed line, which he felt would be more stable. 

It probably would be...  but it could also be considered an easy cop out for BT if they dont know what to try next. :(
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mr_chris

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Re: Very high noise margin drop in afternoon
« Reply #22 on: January 12, 2008, 03:24:12 AM »

>> The other option he suggested was to switch to a 2Meg fixed line, which he felt would be more stable. 

It probably would be...  but it could also be considered an easy cop out for BT if they dont know what to try next. :(

Don't forget you'd lose your additional upstream too if you got switched to a 2Mb fixed line. Whilst it may keep your SNR high enough to prevent disconnections, it wouldn't really solve the issue, just mask it.

Have you ever managed to try another router on the line? Perhaps it might be worth a shot.

Also, do you switch the router off at night? If so, leaving it on would keep the line synced at its lowest speed, so it wouldn't keep resyncing every day. Forgive me if this has already been suggested.

As regards REIN, I think it's only in the remit of SFI to investigate REIN issues.

Actually, having not heard the term in widespread use before very recently, it seems like REIN is set to be the buzzword of 2008, doesn't it! ;)
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Chris

b4dger

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Re: Very high noise margin drop in afternoon
« Reply #23 on: January 12, 2008, 09:36:02 AM »

Well the engineer has been and gone.  Showed him the routerstat graphs with the three o'clock drop off.  Said he hadn't seen anything like that before...

Hi MikeS thanks for the update, sorry to hear you didn't get a fix.

Your SNRM dropping off at dusk is fairly common - especially for those of us on longish lines. As I mentioned earlier my situation is very similar to yours.

Not surprised about the BT comments etc. - my experience has shown that ALL the OpenReach engineers I've spoken to haven't got a grasp of things!  I'm not saying they are all like this, but the dozen or so I've spoken to in the last two years (mostly doing work for my neighbours not me) don't seem to have a clue. I've asked a few if they know about IP Profile (BRAS) etc. when they've been playing with peoples connections (we're rural/overhead) up a ladder, and quite often get the plug pulled with no warning. They all just shrug their shoulders and say "that's the other lot...". Not one has known what line attenuation is, I could go on.

Try a Thomson Speedtouch 585v6 for around 30 and see if it improves things for you as well  8)
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roseway

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Re: Very high noise margin drop in afternoon
« Reply #24 on: January 12, 2008, 10:04:35 AM »

The regular OpenReach engineers are employed as telephone installers and repairers. They're not trained in ADSL, or expected to know anything about it. So it's no surprise that they don't understand the specialist ADSL terms. They do have some engineers who are ADSL trained, but you won't encounter these so often.
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  Eric

b4dger

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Re: Very high noise margin drop in afternoon
« Reply #25 on: January 12, 2008, 10:40:07 AM »

The regular OpenReach engineers are employed as telephone installers and repairers. They're not trained in ADSL, or expected to know anything about it. So it's no surprise that they don't understand the specialist ADSL terms. They do have some engineers who are ADSL trained, but you won't encounter these so often.


We're going OT but,
On one occasion the one's in my lane were all wearing OpenReach logos on their clothing etc. I asked them if they were broadband trained engineers, they 'puffed their chests out' pointed to the logo and said they were trained broadband people not 'wire monkeys'. Then I asked if they knew about BRAS/IP Profile, attenuation, etc. - they went all sheepish and said "arh, that's the other lot"!   

As I said, I'm sure it's not all the OpenReach people but my experience (talking to at least a dozen engineers) has been poor.
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shape

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Re: Very high noise margin drop in afternoon
« Reply #26 on: January 12, 2008, 06:39:02 PM »

Hope you don't mind me adding my tuppence worth.
After my lift and shift my target noise was reset to 6db.
I've just had a final SFI adsl engineer visit, who looked rather perplexed when i showed him my router logs, He kept saying it syncs at good speeds apart from the evening where it has poor sync's, so not that bad he thought.
I agreed yes, but what of my bras, ip throughput will never rise.
He looked confused, I added it would be fine if I was with talktalk as there is no 3day period.
When he visited he told me everything had been done, and phoned somewhere to check if a d-side swop had been done.
Was quite funny as apperantly loads of lines had been moved onto the new telegraph pole, but HQ knew nothing about it as there system had not been updated.
They where arguing with him that he had the wrong telegraph pole, as there was only one line on it, he almost lost it saying i'm looking at the bloody pole now and it has a half a dozen lines on it, lol.
Shows they don't keep the system updated.
He had no ideas what to try next, suggested fixed rate speed, i refused saying i'd lose out on upstream for my gaming.
He wanted to refer it to a REIN trained engineer, but said he hasn't a code to do that.
I suggested ringing my ISP rep for him, which I did.
He explained to my rep he had no code for REIN investigations, and this bit got me, he actually said we normally just con the EU (end user) off!
My rep told him he would call him back after he spoke to his boss.
He did stay for an hour plus chatting and drinking tea, lol.
He confused me, as although he said he wasn't REIN trained, he told me a tale where he was out in a area suffering disconnects on many user lines.
They found it by accident, well away from reported affected homes, was a guys dodgy sky box, blurting noise down the phone line, affecting loads of homes.
Sorry to waffle on.
:-)


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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #27 on: January 12, 2008, 06:53:22 PM »

I think I'm definitely in re-training mode.  Started up this morning sync at 4300 and 6dB, then noticed interleaving was off (it has been on for the last 6 months). Held 4300 until 3.30 then dropped to 4000 then to 3800, currently bouncing around 2dB, will see what the rest of the evening will bring.  currently I feel that the line is a better - previously I would have been at 2300 and 2dB.  Need a bit more connected time to see if this is consistent.  I'm still puzzled why the BT modem sync'd at 2500-2600 (3 different tests) and I sync'd two minutes later at 4000 on my router.

In answer to some of the queries

Kitz
Yes the line dropped off at the same time though not so severely
Engineers notes - they do write them but they are difficult to access, requires a few phone calls I'm told. This is crap Openreach procedures, they should be provided automatically with the visit list.
REIN beyond the competence of the engineer, he said they had been told about it but just as a phenomenon - could sometimes be picked up on medium wave radio sort of thing.   

Mr Chris
Normally I switch the router off at night, I will leave it on as I seem to be in training mode.
I have tried two other router and a couple of modems, unfortunately they were all AR7 chip jobs and showed the same pattern.  The SAR 600EH I'm currently using is by far the most stable in the sense that sync drops are less frequent.  I think this a 600E with a built in homeplug.  The homeplug issue caused consternation with the engineers.  They  asked whether I was wired or wireless, wired I said.  Can't be they said you have only one ethernet cable.  So I had to explain about homeplugs, they had never heard of them.

General comment on the engineers I've had 6 now.  All have been polite, helpful, listened to me and tried to fix the issue within their limited palette of options.  None of them seemed to have much knowledge on broadband max.  I was getting comments like 'SNR and DLM, sorry that's a bit over my head',  'once the line goes into the exchange we don't know what happens'.  The general feeling I got was that they were shifted from voice line work on to broadband with very little additional training.  I think it's a massive increase in technical content going from voice to broadband max. Consequently I think this is a BT/OpenReach lack of training issue rather than an engineer issue.   A couple gave me the impression that they disliked maxbroadband work because all they could do was 'a suck it and see approach' - switch pairs, lift/shift, redo junction box connections etc and see if it made any difference, whereas on voice lines they could actually find and fix issues.

Another general comment on routers.  I have trawled the net for info on my problem and consistantly came across many comments like Router X cured all my problems, wonderful piece of kit,  then another comment saying Router X was total rubbish don't waste your money. I've come to the conclusion that similar spec routers may well perform very differently under specific line conditions - noisy lines, long lines, fast noise margin swings etc.  If that is the case how the hell do you go about choosing a router - aside from assuming you'll probably have to buy two or three before you get the right one.  I think I am going to have to buy a Speedtouch.  I guess BT are the only people who can test routers under different line conditions - would be a nightmare for them commercially.  Just resync'd to 3680 - time to go

Sorry for going on and thanks for all your help and advice



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kitz

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Re: Very high noise margin drop in afternoon
« Reply #28 on: January 12, 2008, 08:22:37 PM »

I had a rather long and interesting convo with Azzaka from Zen yesterday about the AR7 chipset issue.  It could be a possible cause and we did discuss quite a few different scenarios and situations when this could occur.  It is kinda random and yes sometimes a change of router will remedy the situation, but the gist is that the AR7 is a good chipset, theres just something else going on... hopefully more info will come out soon and netgear are working with them on this and hopefully different firmware will be released soon.

I'd hate for you to have to fork out for a new router and then find the problem is still the same..  it there anyone you know locally that could perhaps lend you their router for a short while for testing purposes?  Even if you cant get hold of a speedtouch, try one of the other broadcom chipsets such as a Voyager 2091/2100/2110
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #29 on: January 12, 2008, 11:13:07 PM »

Hi Kitz

Saw some new speedtouch 510v6 speedtouch for 11 quid including P&P on ebay - do these have the broadcom chipset, if so may take a punt on one out of curiosity as much as anything else.
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