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Line fault?

spock
Grafter
Posts: 29
Registered: 09-08-2007

Line fault?

I've been having trouble since being activated on MAX with roughly 1 to 3 daily connection drop outs at random times (usually between 5pm and 3am).
Have read loads of posts on thinkbroadband and dslzone forums and as a result relocated router onto Master socket and replaced NTE5 faceplate with ADSLNation XTE2005 filtered faceplate, but problem persists (in fact its worse!)
Lately have been using RouterStats and/or ADSLMonitor to try and get to the bottom of the problem and this reveals that the Noise Margin is usually variable between 9 and 5 during most of the day, then will suddenly drop down to between 3 to -2, sometimes router will hold on and about an hour to 2 later margin will recover to 6 - 9, other times sync gets lost and a resync 1mbps slower occurs.  During the "holding on" periods the FEC errors shoot up to over 0.5 million in a couple of hours.
It doesn't matter whether we are at home or not so I don't think there is a problem with electrical interference within our property.
I have attached a routerstats graph from yesterday morning showing what I describe.
Router: Netgear DG834G v3 Firmware 4.01.28
Line Stats when good
D/S Noise Margin 9db
D/S Sync  ~4600kbps
D/S Attenuation 47db
Line Stats when resyncing bad
D/S Noise Margin 9db
D/S Sync  ~3700kbps
D/S Attenuation 46db

Raised a ticket early Saturday Morning against intermittent sync but I don't hold much hope of being able to find the issue cause of the intermittent nature Sad
So at the end of all that does anyone here think this is a line fault, or it is what can be expected on dsl-MAX?
Secondly does anyone have any suggestions on what if anything I can do to improve stability?
Thanks in advance
Paul
12 REPLIES
jnwright
Grafter
Posts: 281
Thanks: 1
Registered: 05-04-2007

Re: Line fault?

I used to have a problem very similar to yours, with sudden temporary drops in the downstream SNR from 13dB to as low as 3dB.  The speed remained 8128/448kbps and the downstream attenuation was fairly steady at around 20dB.  I didn't hear any noise on the voice circuit (perhaps I should have listened more carefully) and the fault was not particularly weather related.  I ran ADSLMonitor regularly to see the effect and couldn't find any local cause. I don't have any internal wiring and like you have a faceplate splitter on the NTE5 master socket.  In fact the BT cable only has to come 6 inches into the house to the master socket.
Then, about 3 months ago, a very tall lorry broke the cable across the road from the pole to my house (and another one further up the road).  After about a fortnight, BT erected an extra pole on my side of the road to get a new cable to my house at over the current minimum height over the road.
So after a very annoying, isolated time with no phone or ADSL (mobiles are awful in the Pennines - I had to run outside the house every time it rang to get enough signal and usually lost the call!) I got back online.
Since then my downstream SNR margin has been consistently around 13dB with no temporary lows.  The only thing BT had to disturb was their junction box on the other side of the road.  I can only think that the original problem was a poor connection in this junction box.  ADSLMonitor no longer sees drops in the downstream SNR margin.
So sometimes a disaster can have beneficial results!  I think that your problem may be a poor connection somewhere between your house and the exchange.  My distance from the exchange must be much less than yours, so the problem, although worrying, didn't have as much effect as you are seeing.  Also a fault near the exchange would make the situation worse because the line would pick up more interference on the cable on the way, whereas both interference and signal would be reduced if the fault was close to the consumer.  Therefore I have to suggest that your problem lies somewhere between the master socket and the exchange and that BT need to pay particular attention to all the junctions on the way!
If you can hear any noise on the line, report it as a voice fault.  BT will have to fix it and you'll have less trouble getting them to do it.
Good luck!  I don't suppose you know any drivers of tall vehicles!
prichardson
Grafter
Posts: 1,503
Thanks: 1
Registered: 05-04-2007

Re: Line fault?

I did spot on that there is a sudden increase at exactly 10am. Can you account for anything electrical at this time going on or off?
I agree with the point that if you hear noise on the line, get BT to look into this for you (or whichever voice supplier your with).
Whilst this applies even more so in the case of an intermittant issue, voice faults have a better sucess rate in being resolved. There are either physical causes, or engineers simply cannot argue that they cannot hear noise for example.
Whilst ADSL faults are often very real, it can often be hard to prove that it simply isn't a perception issue. As a digital technology, it can often react very badly to a little noise that may not normally be detected.
spock
Grafter
Posts: 29
Registered: 09-08-2007

Re: Line fault?

Around 10 yesterday we would have been having breakfast which involved the microwave and then maybe we put on the washing machine.
So thats a couple of things to take a look at.
Thanks.
LiamM
Grafter
Posts: 5,636
Registered: 12-08-2007

Re: Line fault?

Microwave... that could do it.  Could do some testing by using the microwave and examining the graphs?
Washing Machine could also cause some interference, but are not as common a cause as Microwaves.
prichardson
Grafter
Posts: 1,503
Thanks: 1
Registered: 05-04-2007

Re: Line fault?

The brushes in the motor will indeed cause this type of problem.
Further review shows that it is bang on 10am when it goes up. Once up, it can clearly be seen that it maintains a pretty static level.
When it drops, it tends to be irratic.
A 3dB drop in SNR means that the signal has halved, so you can see it is a significant flux.
I suggest monitoring it for longer. Graph it and see if you can spot what enviromental changes occur when you see significant changes.
Trust me when I say, don't start thinking that somthing is not to blame until you confirm it. The silliest of things have shown to be at blame.
Unlikely here, but electric fences, TVs in other houses even right down the other end of the street.
LiamM
Grafter
Posts: 5,636
Registered: 12-08-2007

Re: Line fault?

... and at Christmas, the outside lights can cause interference in a big way :-)
prichardson
Grafter
Posts: 1,503
Thanks: 1
Registered: 05-04-2007

Re: Line fault?

Chrismas is a big myth, end of..
Says me who worked christmas eve, day and boxing day last year!
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Line fault?

Seem strange that users experience so much electrical noise considering electrical goods have to meet EMC requirements. Should the authorities get involved?
prichardson
Grafter
Posts: 1,503
Thanks: 1
Registered: 05-04-2007

Re: Line fault?

Potentially, yes.
Reality, you need to prove the equipment was at fault when it came from assembly. Not every device has to be tested, and items can become faulty after assembly, be this beyond testing, or long after the consumer has them.
Some devices can naturally give off more RF than others due to their very nature, some will give off more due to wear and tear. Motors for example will do this.
What doesn't help is that many people power devices longer than the makers recomendations, which is turn damages them and making problems worse.
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Line fault?

The EMC directive does not only cover emissions but also immunity. The immunity requirement is for both conductive and radiated. So are the routers that are dropping the connection meeting the immunity requirement?
mgwilliam
Grafter
Posts: 31
Registered: 18-04-2007

Re: Line fault?

Rather than raise a new topic I am reporting my problem here as it is very similar in nature. I am experiencing a loss of link in the evening just as the sun has gone down and the street lights come on. I am not saying it is the street lights as I just do not know. The SNR drops, line goes down and on reconnect the SNR is back up but line speed down. Then SNR drops again, line goes down and when reconnected the line speed is down further. Last night it held through and this morning the SNR was up to 9db so I rebooted which got the line speed back up. This has been happening for sometime and initially I was suspicious of a Belkin G+modem so I tested with an older modem which I know to be stable.
I have conducted many checks within house such as running from master socket, changing filters etc and nothing changes so I am as satisfied as I can be that problem is not within house. I should add that we have not added any new equipment either.
The previous night I left the Belkin modem on overnight and as it does not automatically reconnect my line speed dropped from around 4mb/s to below 1mb/s.
I have run the broadband fault checker and now await further guidance but if anyone within the forum can offer any useful help and can suggest best settings for the Belkin I would be most grateful.
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Line fault?

Hence the immunity requirements cover conductive noise, whether this is down the mains cable or other cabling.