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[indigobanana]

Hi there,

I found your website a while back, and its really useful, thanks for all of the valuable information!
However lately, i've run into a problem with my ADSL connection, and im wondering if any of you would possibly know whats up with it?

Basically i've been experincing a lot of loss of Sync, and after looking at the router stats (Bt voyager 2100), the noise margin seems to hover on about 21db before shooting down to 6/7db or below, and often this causes a disconnection. It seems like noise spikes or something?!

I've made sure all the filters are corrected, and im pretty sure it isn't anything inside the building causing the problems. However after monitoring it for a few weeks, i noticed sometimes, when trains went past, the SNR would go crazy and the line would often disconnect. Just for the record - i live very close to the West Coast Main Line, and im pretty sure its some of the Virgin Pendilino trains that cause the disconnections. So i think it must be some kind of REIN interference caused by these superpowered trains?! I know - its bizzare  Just to clarify though - this is only sometimes, and other times it seems to disconnect with no passing trains (although this is rarer).

Also i forgot to mention im currently on a 1mb fixed speed broadband profile.... and i think i need to get this sorted out somehow before i upgrade to max, right?

Heres some graphs from routerstats, that i left running overnight and into the day...
http://www.indigobanana.com/storage/graph1.jpg
http://www.indigobanana.com/storage/graph2.jpg
http://www.indigobanana.com/storage/graph3.jpg

Please help!! I really hope this can be sorted, do you think an engineer would be able to fix it or something?

Many thanks, Jamie

[indigobanana]

Here are the current stats:
(the noise margin seems to be OK at the moment)

Line Rate    1152    288    
Noise Margin    20.8 dB     24.0 dB     
Line Attenuation    39.5 dB     24.5 dB     
Output Power    12.1 dBm     15.9 dBm

I'll try and post the stats again when a Virgin Train is passing 

edit:
Sure enough, minutes after i posted this one passed. And i was monitoring the router page... for about 3 minutes before it passed the noise margin got smaller and smaller, and when it passed i recorded this:

Statistics    Downstream    Upstream    
Line Rate    1152    288    
Noise Margin    8.3 dB     24.0 dB     
Line Attenuation    39.5 dB     24.5 dB     
Output Power    12.1 dBm     15.9 dBm     

So quite close to disconnecting...

Sure enough, its now jumped back to about 18db.... 

[jid]

Well, looking at those graphs it seems that there is as you expect serious REIN there.

Trains could possibly be the problem, or it may be that the copper connecting your home to the exchange runs under the line?

Ezzer, is the forum's resident BT engineer and REIN expert so perhaps he has seen the effects of trains on SNR?

Also, have you had a look at the radio trick further down this link:-
http://www.kitz.co.uk/adsl/rein.htm

Regards

Jamie

[Ezzer]

Havnt had a rail caused REIN so far however anything electrical can cause a problem.

snr  from 20.8 to 8.3 is a big downward jump and from what you describe does sound like a potential REIN fault. try the REIN faulting methods on this site to see if there is a connection to you problems to the enviroment you have and report it to your isp

[orainsear]

How close to the track are you?

Also can you have quick look at http://www.kitz.co.uk/adsl/adslchecker.php to see if your phone line has to cross the train line to reach the exchange?

[indigobanana]

Hey, thanks for your help and sorry for the late reply.

I decided to go and buy myself a cheap AM radio, and the results have been quite interesting.... I've been following the instructions for diagnosing REIN and some places in the house seem to have an interesting effect on that frequency. For example something that sounds like warbling aliens and water, on the landing. Its hard to explain.
Anyway, i left it by the window, facing the train track, and sure enough before a train went past it got louder with a high pitch buzz, which stayed the same pitch for a while and then went to a slightly lower pitch.
So basically, do you think this interupption is affecting the exposed telephone wires outside?

Thanks for your help!
Jamie

[indigobanana]

How close to the track are you?

Also can you have quick look at http://www.kitz.co.uk/adsl/adslchecker.php to see if your phone line has to cross the train line to reach the exchange?

I'm very close to the line, 30 metres. Looking at the map the phone line does not cross the track at all, however I know that map is an estimate and does not plot the actual phone line, just the quickest theoretical route from the postcode to the exchange. Looking out of the window, it appears my phone line goes onto a pole which is on the edge of the road, about 15 metres from the railway. Also, we're next to a "depot", and they seem to have some kind of massive transformers and additional electricity pylons, so this is a REIN nightmare, right?

Do you have any ideas Ezzer? I have reported the problem a week ago to Tiscali, however i have had no response yet. But even if the case got escalated -  Im not sure if any BT engineers would be able to do anything about this anyway? My big concern is that it would severely effect any attempts to get ADSL Max... and end up with an exteremely low profile.

Jamie

[waltergmw]

Hello Jamie,

30 metres from a high voltage, rapid-change high current installation is certainly not an ideal position from an electrical noise viewpoint.
Regarding the line routing it's probably more important to see if your BT line runs parallel to the railway and how much unscreened overhead cable is involved.

Your readings seem to show distinct drops at specific times which I expect you could correlate with certain train times.

Removing such problems is likely to be quite difficult and your ISP is probably not the most enthusiastic one to help their clients.
Higher cost ISPs tend to have better technical support and fault logging systems. They can usually afford to pay BT Openreach to examine your fault in BT's equipment. It will be important to show your diagrams via your ISP to BT to demonstrate the type of problem.
Curing such problems might involve using screened cable earthed at one end only or possibly getting Network Rail to look at their earthing arrangements.

From the self-help viewpoint have a look at my other comments this morning about connecting a router directly into the filtered master socket.

I hope this helps,
Walter

[Ezzer]

Without being on site its difficult to say what the cause is particualy with REIN. From what you describe with the nose with a passing train and the drops in sync/ loss of snrm quality at the same time it may well be linked to the trains.

Although what part of their electrical network is generating the noise and what aprt of your telephone network is picking the noise up is very difficult to pinpoint.

[waltergmw]

Ezzer and Jamie,

I suggest that once it is established that the railway system is involved there's very little to be gained by looking in detail as it will be so difficult to establish exactly what is transmitting the noise affecting the phone circuit and even more difficult, if not impossible, to stop or limit the actual transmitter(s).

My earlier suggestion to concentrate on making the phone and modem as noise-imune as possible tackles those items where there is some potential to improve matters. I.e. connect the modem into the filtered NTE5 master socket which hopefully is as close as possible to the phone cable entry point inside the house. This work need not involve the ISP or BT Openreach (unless there's no NTE5 or house cabling is connected in a star configuration). If this has no noticable effect then the ISP has to become involved.

Kind regards,
Walter

[indigobanana]

Thanks for the advice.

The modem is currently connected to the NTE5 Master Socket, at the entry to the property, so theres not much i can do on that front. During "normal" times of the day, where there is no noise, the noise margin is a steady 21db with a line attenuation of 40.0db, with the fixed line rate of 1152kbps, so I presume(?) that the line is in a fairly good condition under normal circumstances, when it comes to anything that could be affecting the line from inside the property. The ugly SNR spikes definately coincide with the trains, most of the time, and it starts slowly deteriorating a few minutes before the train passes. At this point the noise margin goes up to about 6db without disconnecting, however a lot of the time it causes a loss of sync to the exchange. After the train passes the noise margin shoots up to normal within 30 seconds. Although with some trains, there is no affect at all.

I'll try and get some pictures for you tomorrow, showing where the phone line goes and the equipment on the railway. Another theory i had (although one im doubting more now) is the actual noise/earth vibrations caused by the passing trains, adversly affecting the noise margins. However I dont think it can be this, because some trains have no effect on the noise margin at all - which is the really baffling thing. Hmm I guess i'll have to see what Tiscali's technical support team come up with...

[waltergmw]

Hi again Indigobanana,

You mentioned that there was a substation close by. If the "bad" trains start the deterioration a few minutes beforehand, and the trains are travelling quite fast, perhaps it's the substation that's causing the problem ? However against that idea is that all trains should produce similar results.

Another idea is that some trains might be coasting so would be "good" ones wheras other "bad" ones are, say, starting from a station or ascending an incline they would be drawing much more current.

Yet another idea - if it's only Pendolino trains - I think I read somewhere that they use regenerative braking. If so you're looking for a train slowing down for a station signal or descending an incline. They also have a lot of electronic services available for the passengers but that is a very long shot.

You might have to become a trainspotter again !

I mentioned substation earthing as many of them can have significant earth currents which will require a good low resistance earth.
Please note I'm not a railway expert so some of these thoughts could be off target. Trying to persuade Network Rail and / or Virgin to investigate could well be a long hard task. Similarly getting the remains of what used to be the Radiocommunications Agency to investigate unauthorised broadcast transmissions is likely to be difficult.

There can be little doubt that a move to a rate-adaptive service whilst you still have these "features" in your area is probably a bad idea.

Kind regards,
Walter

[Weaver]

Hi Indigobanana,

You could try some of the anti-noise, mains pollution and RFI measures I've implemented.

i) try filtering the mains into your router; I tried a Belkin PureAV Isolator unit

ii) put ferrite chokes on the DC power cable into your router from its power brick

iii) try twisted-pair RJ11-RJ11 phone line cables to your router; shorten phone line cables

iv) put your router onto a UPS in case the trains make the mains droop, (possibly worse for noise, so filter the mains output from it)

I think you said you've already tested direct into the master socket's, but just so I am clear on this, you did take the front off and plug straight in to the test input? So you will have disconnected all phones and disconnect extension wiring temporarily in case that wiring is picking up radiated interference.

[waltergmw]

Hi yet again Indigobanana,

Ezzer might be able to confirm what might be possible from BT Openreach re the following ideas.

As well as those ideas mentioned by Weaver you could ask BT O to move your master socket.
I wonder whether they would provide screened overhead cable? Perhaps they could be persuaded to install, say, a screened 10 pair catenary cable. BT O could install an external junction box where the line meets the side of the house. Then you could possibly give BT O some ftp ethernet cable** to run down to the NTE5. It's very important that all screens / drain wires are only earthed, to a good low impedance earth point, at one end to prevent circulating currents.

** FTP such as:-
http://www.cablemonkey.co.uk/cgi-bin/sh000002.pl?REFPAGE=http%3a%2f%2fwww%2ecablemonkey%2eco%2euk%2f&WD=ftp&SHOP=%20&PN=Cable_Monkey_Shop__Cat5e_FTP_Solid_148%2ehtml%23a001_2d004_2d010_2d10#a001_2d004_2d010_2d10



(Also re Weaver's notes, do check that the ring wire is not connected before you replace the NTE5 face plate.)

Kind regards,
Walter

[attachment deleted by admin]

[Ezzer]

The best option here is to have a REIN fault raised so a REIN engineer can try and do their best at locating the source or probable source. If this comes from a 3rd party then Bt cannot do anything directly but as I understand this the issue is passed over to a branch of Offcom which regulates emf problems.

As far as screened cable is concerned the problem with REIN is where on the network is the interference picked up so this is hit and miss without screening the entire pair from the exchange to the router. external cable isn't screened. and theres only one engineer I know of in this area who carries screened internal cable on their van 

Officialy before a dsl fault is raised as a REIN fault then the normal procedures are changing e-side pair, d-side pair fitting a new nte5 with ssfp and an rf3 and if required replacing the dropwire (in the case of drop wire3 the grey 2 core type definate replacement) Althoug if a REIN signal is definately identified then this needs to be sorted as other attempts to get orund the problem may only partialy improve service on what should be working much better an the reason REIN may exist may well mean the REIN gets worse at a later date affecting possible many people. 2 recent REIN faults I know of would not have been solved by any form of screening. the source needed to have identiifed and removed/repaired. Could be part of the rail cableing in you locality is faulty and generating the noise so needs to be loked at. may well help railtrack or who ever sort something that will become an issue for their service seperate to telecoms