Understanding sync speed, SNR margin and Errors

[#1]

On another note - my exchange is planned to be upgraded to 21cn at the end of the month. Is that likely to make any difference?

[#2]

Your exchange being converted does not mean that your line will be changed across to the new hardware immediately. You may have the option of going to 21CN or staying with 20CN for a while and if you go to 21CN then you may have a choice of going to ADSL2 or ADSL2+ or sticking on ADSL1.
Which you choose should perhaps depend on how regularly the noise occurs. If the interference occurs say once per day then the DLMs on both ADSL1 and 2 will chop your speed and never get around to improving it. However my experience suggests that the ADSL2 DLM goes on making things worse and worse as each burst of interference happens while the ADSL1 DLM does so much less. On the other hand, if the interference is only say once a week, then the ADSL2 DLM will improve things again and do so more quickly and more thoroughly than the ADSL1 DLM will. The timescales are just an indication. So far, I have not managed to get a definitive answer - perhaps there isn't one - on whether its hours, days, weeks or several weeks in each case but it slows down much faster than it speeds up again.
There may be options to limit the effect of the DLMs but that has its good side and its bad side too. So you pays your money and takes your choice. I am trying to decide what choice to make at the moment but there is little doubt that the best solution is to get rid of the interference.

[#3]

I've now managed to borrow an old AM radio from a friend. I know to tune it to 612kHz (but it's an old one with a dial so hopefully I don't have to be that accurate). I tried it a bit last night, but wasn't really sure what I was looking for. Putting it next to my TFT monitors gives a sharp whine, but not really sure what else I should be listening for - does AM get picked up through the metal extendable aerial or through a 'ferrite rod' in the main part of the radio. I tried to find website that had a recording of REIN so that I could know what to listen for, but all I found was a broken link on http://forums.thinkbroadband.com/general/t/3812920-rein-afflicted-line-chances-of-getting-it-investi....
So if you handy people could answer me a few questions then hopefully it will help me in my search:
1) How accurate do I need to tune the radio?
2) What exactly am I listening for? I tried last night (when there wasn't REIN) and only really heard a buzz when I put the radio within about 10cm of the ADSL router
3) How do I use this to direction-find? I think that the direction of the REIN source is directly out the back of the radio (perpendicular to the front/back) - is this correct?
4) Does the low SNR in routerstats correspond exactly to the time/strength of the REIN? Or could a short pulse of REIN that only actually lasts a few seconds show a SNR reduction for an hour or so?
5) Should I raise this as a fault with plusnet and then ask that this gets investigated by BT (after providing a week's worth of graphs from routerstats)?
Thanks. Off home now to wander about with a radio (though the graphs show there is no REIN at the moment as I'm at 13dB SNR 😞
Steve

[#4]

1. It doesn't have to accurate, just off-tune i.e. in between stations.
2. The noise will vary depending on the frequency of the interference.  Basically it's a noise that gets louder when you approach the source and comes and goes as you point the receiver in different directions.  In my case it was like an outboard motor.
3. Stand a bit further away from your equipment and see which way the radio points when the noise is loudest.
4. Initially Yes; if you hold sync speed the SNR will go back to normal as soon as the REIN stops. However, if the REIN causes you to resync at a lower speed the SNR (r  = ratio) will increase (lower sync = stronger signal), hold steady at a higher value and then increase more when the REIN stops.
5. No harm trying it.   It will probably take ages to get a BT REIN engineer on your case because they are scarce as hen's teeth.  See my history here:
http://community.xilo.net/topic/1001-noise-burst/#entry6268

[#5]

REIN:
Recorded a month ago from a 1970's era transister radio, onto a Samsung laptop.
Location: along a rural roadside verge adjacent to a BT pole feeding a certain few houses which I believe to the be source of my difficulties
Radio frequency tuned to around 612KHz.

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[#6]

Thank you both for the reply. I had a bit more time to wander around with the radio this evening, but (as these things happen!) I haven't had any REIN all afternoon apart from a 3-minute burst before I got back from work. So I couldn't make any progress tracking it down, but at least I've got a slightly higher (3Mbps instead of 2!) broadband this evening due to the higher sync rate. I'll keep an eye out for it over the weekend and have set the alarm on Routerstats to alert me when the noise happens so that I can go prowling with the radio (now that I know what to look for!).
Many thanks to you both - hopefully it is a neighbour's house and something I can find - in which case we can sort it out between us (on good terms with immediate neighbours). If not (or I can't find it) then at least I'm creating lots of graphs and I know that I can get PN/BT to try and get a REIN engineer out here in the next few months.
😄

[#7]

You guys are amazing! Thank you so much. The REIN started happening today part-way through the last set in the Murray match, so I turned the radio on. As it happens, I needn't have asked for what REIN sounded like as there was no mistaking it - really REALLY loud buzz compared to any radio station. So I went wandering around. First turned my house off at the main intake (nothing more embarassing than pestering neighbours to find out it's your problem!!!) and that didn't stop it, so wandered around the neighbourhood.
Using the radio to try and find the direction of the REIN was not easy at all - but as I wandered away from my house, it got quieter, so I started wandering back and it was loudest around my house and my neighbours. Fortunately we get on well so I knocked on his door and it turns out it was the power supply to his monitor unplugged monitor and it went silent, then plugged it back in and waved the radio over the monitor itself and the power supply - louder at the power supply. Strangely, he says that their internet connection is terrible (wonder why!!!).
Anyway, there may be another source locally but that one's definitely the closest. We're going to try and buy a new power supply (I offered to pay but he's quite happy to pay) and so hopefully once this has been done, I'll let the graphs roll and just keep an eye on them and if all is flat for a few days I'll notify PN to have them (and BT) up my IP profile (and probably check what my default SNR margin is and drop it to 6db - I think it's 9 as I always connect at about 8.5) and then hopefully I can move from about 2Mbps to around 5! 150% increase due to (hopefully!!!!) replacing a neighbour's power supply.
Thank you to all you who offered advice - without you I'd have just sat here grumbling about being in the countryside and accepting a noisy and unneccessarily slow connection!

[#8]

... anyone know a good source to get replacement power supplies? Amazon would be my first call.
I assume that I need to check:
Input voltage is AC 230V (All should be if they are mains powered)
output voltage matches
polarity matches
size matches
output amperes of new power supply is at least that of the old one (I assume that I don't have to match the output current - just make sure that I get one that can handle at least as much as the old one??)
Thanks

[#9]

Google came up with this site:
http://www.powersuppliesonline.co.uk/power-adapters.html

[#10]

Ace result!

Quote from: agentgonzo

Strangely, he says that their internet connection is terrible (wonder why!!!).

Sadly this is the usual scenario.
The offender in REIN cases is probably affecting the broadband of all the surrounding houses, 99% of whom do not notice, and probably don't care anyway.
Meanwhile the purpetrator is wondering why their broadband is almost totally non functional.
In today' environment of gadgets everywhere there is always going to be electrical noise picked up by the phone line, so there will certainly be other sources affecting your phone line, most indeed will be working normally when they do.  Hopefully any other malfunctioning ones will be far enough away not to affect you.
If your computer/router is on a Uninteruptable power supply(UPS) and you are lucky enough for it to be all fully powered fully on, with RouterSats running when there is a power cut affecting your local area then you will get an interesting surprise.
All those local electrical/RFI noises will vanish so too will all the cross talk from other people's broadband within the BT cables back to the exchange. Also ceasing will the general buzz from the electric cables in the road etc.  Only homes likewise on UPS's will be working.  All the DECT/mains powered phones will not be operating.
The effect on my line of a power cut is to raise the SNR margin from just over 3 to not far off 8 and when I was on 20CN from 6 up to 12.
Last time it happened I was thinking of doing a re-sync during the cut to see what sync I could really get in the absense of all this 'noise'  This would have enabled me to get a reading of the Quiet Line Noise under these circumstances which is only done/available at re-sync - but I thought it might not be too good an idea......

[#11]

Also, it's a shame I never listen to 5live. Tunes the radio just to see what I could pick up. Nothing. Nothing at all. The entirety of medium wave and half of long wave is just a buzz. No radio stations at all!!

[#12]

@agentgonzo
As you've discovered any frequnecy may do, it just depends on the frequency at which you detect the interference strongest. I have for example, one coming up my mains that is pulsing at about every ½sec. which I get strongest on 531kHz. I believe it's a digital clock, possibly the one on next door's cooker but they also have a sky box, so I'm not to sure at the moment. However none of it is causing me a specific problem, just a minor inconvenience sometimes. Glad you found your (hopefully) major problem.
Yes and you are quite right about replacement power supply - voltage match and at least the same current.
@x47c
That's a real interesting noise. Does it get any louder if you are right outside any of the houses?

[#13]

I can't really get any closer - this is a rural area with 25yard+ house drive lengths and houses set back from the road.
The recording was taken about 1m away from the BT pole and underground joint box that feeds the phone supply to the three property's from where I think the source is emitting and it's where the sound is the loudest on the radio when walking back/fro along the road.  In fact you'd end up convinced the BT pole was the source!
One property's entrance is next to the pole and the other two are across the road from it.
I have established that when there is a power cut locally the REIN/noise ceases.
I'm waiting for when there is a long gap without any interference and then try and see which one of the three are away on holiday....

[#14]

It's amazing how much background noise (and cross-talk from adjacent circuits) there can be, in addition to any RFI. When we had a cut not so long ago only affecting a portion of the local properties (167 went off), without looking back for the detail, I was synced around 75xx, SNRM was approaching 8dB which went to around 14dB when the cut occurred. No doubt if I'd tried a resync I could have achieved 8096, not bad for a 3km line!

[#15]

Hopefully that's the problem sorted. As it turns out, I had a spare power supply for a small TV kicking around so he's borrowing that for the time being until he buys a new one. Just done a resync and I'm at 5.18M sync speed as opposed to somewhere between 2.5 and 3.5 I've been getting recenctly.
PLUSNET STAFF: Can you please reset my IP profile (and get BT to do the same) so that I can get super-juicy speeds now? Also, can you let me know what my target SNR margin is? I've just resynced and it's reconnected at 8.1 - if the target SNR margin is set to 9db, can I have it dropped to 6db now that I've (touch wood!!!) sorted out the REIN problem? Thanks!