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[Chewi]

Hello all. I moved here to South Queensferry back in October. I wasn't able to stick with Virgin as they don't serve this area but I was looking forward to signing up with AAISP. After getting connected, I found that the connection would frequently drop out in the evening. I just shrugged it off to start with but when it didn't go away, I realised that something must be up.

Knowing that AAISP is like the Rolls Royce of ISPs in this country, I wasn't about to point the finger at them but I asked them on IRC about it and the frequent "Tx rate (adjusted)" messages I was seeing in their log. They initially wanted to rule the basics out. Admittedly I had put the router on a new extension from the master socket and it does sit next to a lot of other equipment but I was sure that the disconnections had occurred before putting it there. They still insisted that I plug it straight into the test socket, away from any other equipment. I wanted to be sure too so I did just that and left it that way for a week. Several disconnections happened in that time.

I contacted AAISP again and that's when I first heard about the perils of REIN. The guy said a street light was likely as the disconnections and log messages appeared almost exclusively when it was dark. I then went in search of an AM radio. I swear I had buckets of them when I was growing up but had none to hand any more, except in the car, so I grabbed a cheap one on eBay. I walked up the very first street light a few meters from my front door. I was still a couple of meters away when I heard BZZZZZZZZZ! Aha! I then checked all the other street lights around. None of them had any effect.

So I gave the council a call the next day. They were a little puzzled about my complaint but still managed to send engineers a couple of days later. I would have been impressed but they were equally clueless about the issue. I had hoped that they may at least have some idea. I didn't know what part they needed to replace and neither did they so they just replaced the head of the light. I asked them to let me check it before they left but they simply drove off before I had a chance to stop them. I would have stood there and waited if it hadn't been pouring with rain and my daughter hadn't been alone in the house. I hoped for the best but it wasn't long before it cut out again and the radio confirmed that the problem was still there.

I gave the council another call. I had since learned that it was most likely the ballast that was causing the problem so I relayed this information. I didn't know exactly what this was and neither did they but they said they'd send someone out again. The Christmas break was over though so I wasn't going to be around to see it. Several weeks went by with no improvement in the situation so I called yet again. They said something about it having passed an inspection, whatever that meant. I didn't entirely blame the council as they were simply stuck in the middle but I was getting a little fed up so I asked whether I could speak to the engineers directly. They weren't able to provide me with a number but said that they'd pass my number on. Both they and I were doubtful that I would get a call. That was January. I've heard nothing from either party since.

I let things lie for a while. In that time, the disconnections have become a little more random. Obviously it stays lighter for longer now but we're sometimes seeing disconnections in the middle of the day. Days will go by where it doesn't cut out at all and then we may see a whole string of disconnections in a row. Curiously, the neighbours moved out and that house lay empty for 2-3 weeks. I'm fairly sure it didn't cut out once during that time. I thought that perhaps it had gone away once and for all until the new neighbours moved in and the problems returned.

The neighbours on the other side have told me they haven't had any problems. I asked the new neighbours and they said they had noticed it cut out a few times; I probably notice it more because I get an e-mail notification each time. I also asked it they had any tube lights such as in the kitchen but they have regular bulbs throughout. Obviously new neighbours means a new set of appliances so if the problem is originating from their place, it must be something built in.

I used to see disconnections throughout the night though at times like 4am so the street light seemed far more likely than the neighbours. That period when the house was empty does make me wonder though. I had a disconnection just now so I rushed out to the street light immediately. Sure enough, it was buzzing away even though the light was off. Conversely, I have occasionally found it not to be buzzing when the light was on. What does that mean? In other REIN cases I've read about, I had got the impression that the light had to be on to cause problems. There's also an electrical substation on the other side of the neighbours, just to add further chaos to the situation.

I started running RouterStats against my TG582n the other day. Apart from a couple of brief downward blips where it didn't disconnect, it's stayed fairly steady around 7.1dB until the disconnection today, where it suddenly dropped to 6.0dB and it's stayed there since. I may check on the street light again after posting this to see if it's still buzzing and then see if the buzzing stops when the dB level goes back up. I want to be a little more sure that the street light is the culprit before wasting effort on the council again.

I gather FTTC has either just become available here or is about to be. I did plan to upgrade but I don't think it'll help the situation, if magicone's epic thread from a few years back is anything to go by. It may even make it worse. The exchange is a fair distance away but I've just learned that the cabinet is only about 200 meters away, which isn't so bad. There's no avoiding that damn street light though!

Apart from the issue about the light being on or off, I don't really have any questions as such. I just thought my experiences may be of interest. Any tips would be much appreciated though. Cheers!

Update: So I went back out as promised and noticed for the first time that the street light may not be the source of the buzzing after all. It's very close to another house (not the new neighbours) and if I put the radio up against their wall, it's much louder. Hrrmm. Looks like I'll have to knock on yet another door. As you've probably noticed, REIN does start driving you mental.

[JGO]

You don't say much about your precautions to avoid receiving interference.

Legally yes people shouldn't use accidental interference producing devices but the attitude has always been lackadaisical, so help yourself first !  (In the 1880s trams cause interference to telegraphs so  people used twisted pair to reject it) 

A filtered faceplate Mk1 decouples the bell wire and is usually set up to make all sockets, except the master,  phone-only. You can try out the effect by using the test socket.

Doing this has doubled my ADSL rate to nearly the theoretical max for this attenuation. It may be that if you do all this the rate may still be lowish because BT/ISP has  upped the S/N margin so you have to lean on the ISP to lean on BT to drop it down to 6 dB again.
 In addition you could use a RF3 common mode rejector, particularly with open wire connections.

Regarding FFTC I'm in a similar location but
1) don't need high speed and
2) FFTC = more bandwidth in Hz = more interference !

[Chewi]

Fair enough. I was under the impression that there wasn't much you could do about REIN except fix it or put up with it.

I am a technical guy, a software engineer by profession, but this stuff is a little outside my comfort zone. I did do a little research, mainly to get the extension connected. I have heard of these filtered faceplates but I didn't think it could make such a stark difference. The problem is my master socket is nowhere near where I need it to be, hence the extension. Most people would just rely on wireless but I have some equipment, including a server, that I really much prefer to have wired. I use VoIP primarily but my analogue line acts as a backup and feeds into a Siemens Gigaset box that can handle both. For this reason, the filter is located on the extension socket instead of on the master. If I filtered it at the master, I'd have to run two cables all that way. Now I know all this doesn't help you get the best out of your line. I did some casual tests with speedtest.net before and after and observed a small drop in performance. I can live with that but I believe the disconnections are a different issue. As I mentioned above, I plugged the router straight into the test socket with no other equipment around. I didn't even have an analogue phone connected at that time. Yet I still saw plenty of disconnections.

I did read about the bell wire causing problems so I only connected the white/blue and blue/white wires when connecting the extension. In fact, I peeked behind the master socket (carefully!) and saw that only those two are connected back there anyway.

The RF3 certainly sounds interesting. Is it better to wire it close to the master socket or the extension? I could see arguments for both.

[JGO]

RF3  -  aims is to reduce common mode pickup on the input cable to the modem so I would tend to put it as close as possible to the modem i/p.  I'm experimenting with one but it seems that in my setup the slight reduction of residual interference is just about balanced by it's insertion loss so no great gain ! It certainly sees off a dip in bits/tone at 198 kHz (I'm about 100 miles from Droitwich !) and pulls some 800 - 950 kHz signal out of the interference. (This is using DSLstats  monitoring bit/tone ).

I understand you can connect the filtered faceplate to filter ALL sockets, but that means all the extension wiring is available as an aerial for interference not just the lead in. Either way it eliminates dangling microfilters which can be damaged by children/animals/vacuum cleaners.

Interference can get into your router via the input cable and/or the Ethernet (or w.h.y. cable) and/or the power leads . Most probably you have high frequency REIN via input and lower frequency noise/spikes via the power line.
(I assume you have buried cables not open wires on poles which are a good aerial  -  someone with open wire gets trouble from a station in Lithuania !!)

Suggest you need to monitor and classify the type(s) of interference you are getting and then sort out a strategy.

South Queensferry ? MESL ?

[Chewi]

For the sake of a few quid, the RF3 sounds like it could be worth a shot. I may just order one.

Thanks for mentioning DSLstats. I didn't know about it so was running RouterStats through Wine on Linux. That worked fine but native is always nicer. I was going to compile DSLstats from source but I don't have a Pascal compiler handy.

I'm not sure how to interpret the bit/tones screen so I'll just upload a snapshot. The cables are buried so I can at least rule that out. I just checked outside that house again and it's still buzzing away much louder than anything else I've picked up so I'll probably call round there tomorrow for what it's worth. I've spoken to them before, mostly when our removal van accidentally knocked down their garden wall. Way to make a first impression.

I'd never heard of MESL but I guess you mean http://www.meslmicrowave.com? Not sure if you were serious but I doubt it would be that as it would surely effect everyone in this relatively populated area. Shouldn't I be looking closer to home?

[JGO]

Yes DSLstats is nice - Roseway had done a good job.

Your results look healthy - but you've cropped the S/N and Speed.
Program takes time to explore but I seem to remember the 4.50.1 has facility for logging breaks - could be very useful  to you.

What it means - suggest Wikepedia but briefly XDSL is divided into 4 kHz odd wide channels,( bit like  L & M wave radio) and each one is phase modulated so on a 2 bits/channel system (say) you have 0,90,180 or 270 degrees phase. The noise in that channel must be so low that signal + noise vectors can still be be identified to the correct phase eg max of +/- 45 degrees noise for 2 bits. Lower noise means more bits/channel is possible.  The  "S/N margin" and "Speed" is the average (?) of all channels. ( You have to be a 7th degree BT wizard to know this !)

Mesl - no, a redherring. I just wondered if you had any connection.

[Chewi]

Here's S/N and speed. The downstream S/N dropped a little to 5.6dB since the last disconnection. Curiously I noticed that the upstream S/N actually went up.

I more or less get that little bit of science. Maths and Physics were good for something.

[JGO]

Another bit of science to remember :- Vector addition.

If an interference component is entering by two routes, killing one CAN make the result bigger if the two components weren't close in phase so don't make a 1 bit decision "It doesn't work ! "

 

[Chewi]

Had a disconnection and rushed over to that house to check. No buzzing. Not sure if that rules it out. Could it knock the connection out when it goes off as well as when it goes on?

That may not matter though. I got the RF3 today. This page tells me it needs to go before the NTE5. I suspect that's not strictly true, especially since I don't actually have anything plugged into the master socket. I hope to give it a try before the weekend.

[Black Sheep]

It's just like the 17th Edition Electrical Regs, Chewi. You don't have to follow the guidance but should any issue arise, the guidance given will be taken as 'Law'.

I appreciate you sound like you are more than capable of installing an RF3, either before or after the NTE, just pointing out the facts. 

[JGO]

RF3  -  aims is to reduce common mode pickup on the input cable to the modem so I would tend to put it as close as possible to the modem i/p.


Interference can get into your router via the input cable and/or the Ethernet (or w.h.y. cable) and/or the power leads . Most probably you have high frequency REIN via input and lower frequency noise/spikes via the power line.

Suggest you need to monitor and classify the type(s) of interference you are getting and then sort out a strategy. 

Black Sheep  On wiring regs  agree with you BUT I have known sound designs spoiled by bone- headed sticking to power wiring practice at say 300 MHz,  sometimes you have to think !

The RF3  etc are aids to remove common mode interference PARTICULARLY where you have an aerial to pick up interference,  like open wire telephone lines, or extension phone wiring. If you can remove  the source of the CM problem with underground lines or a phone only extension they have less, zero or even a negative affect.  If you can't, then RF3 etc may be your best substitute.

[Black Sheep]

Sorry, I may not have put across what I intended to say, JGO.

I meant that Chewi has mentioned he will probably install an RF3 elsewhere other than before the NTE5. I was merely pointing out 'The rules' as laid out by BT. 

[burakkucat]

Just a comment as how the circuit is connected to the NTE5/A in The Cattery.

The aerial drop-cable is terminated at a plain BT80 in the roof-space. From there, a length of CW1308 cable leads to the NTE5/A. When I initially decided to test a BT80-RF3, it was installed by performing a straight swap -- BT80-RF3 for the BT80. 

Currently I do not have the BT80-RF3 in circuit but I feel I ought to check again, paying particular attention to a certain broadcast transmitter that radiates on 198 kHz. 

[JGO]

Sorry, I may not have put across what I intended to say, JGO.

I meant that Chewi has mentioned he will probably install an RF3 elsewhere other than before the NTE5. I was merely pointing out 'The rules' as laid out by BT. 

Fair enough, but when the rules were set up,  was the aim to protect phones or XDSL ?

There is a considerable difference in sensitivity, without considering that a phone needs to be driven hard into non-linearity to suffer from say Droitwich.  When you throw in ADSL2+ and VDSL,  the wavelengths for possible interference can be much less so the "aerial " needn't be anything like as long, say 30 metres as against 1500 so I  keep the unprotected cable short.

What I'm saying is that interference measures need to be focused.
   

[Chewi]

Well I fitted the RF3 today and it has almost certainly made things worse. I always knew that was a possibility but I am obviously disappointed nonetheless. I think there's been 6 disconnections since I hooked it up only 8 hours ago.

I noticed that there was no significant change in my SNR margins. I also read up on this subject a little more. My downstream seems to hover around 6dB and I gather that's pretty bad. Meanwhile the downstream line attenuation is 36.5dB and that's pretty good. I wondered whether REIN is likely to have this sort of constant affect on the SNR margin or whether that would show up in a more variable fashion. I also wondered whether it would be worth setting a different line profile. A&A allows me to do this myself.

I spoke to some guys on A&A's IRC channel. The impression I got was that setting a different line profile would be more of a last resort and may not help anyway. I'm currently on a 6dB profile and am considering a 9dB profile. I'm not sure what impact that will have on the speed. I don't mind compromising a little but if it's that bad, I'll probably pass on that option.

The guys asked me all sorts of questions about the usual culprits and then some but it all seemed to come back to the fact that it has been a good while since I tried isolating the router on the test socket and I really need to give it another try in case the nature of the problem has changed. There may even be more than one problem. It's a little awkward to move it but I'll give it a shot tomorrow. It'll be interesting to see if this has any effect on the SNR margins. I didn't know about any of this stuff the last time.