Kitz Forum
Broadband Related => ADSL Issues => Topic started by: sheepfarmer on April 03, 2016, 03:25:44 AM
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Hi, I was hoping if some of you could help me out with a problem I seem to be having.
About a month ago, I signed up for the co-op phone & broadband's ADSL2+ service. Prior to this I was on Plusnet VDSL2 (40/20) and just before that Plusnet ADSL - this was from a property transfer where I had Plusnet there; in the previous property I was on a Market 2 exchange and had an ADSL2+ service with them, while in my current property the standard BT Wholesale ADSL is ADSL1 only (though Plusnet did hold my Market 2 price rate until I did switch to VDSL2 with them).
When I initially moved in to my current home, the Plusnet ADSL download speed was "only" 6.5 to 7 Mbps. Not criminal or a bog standard ADSL Max service but I suspected more could have been done. The previous occupants I suspect had a VDSL service before they left as the master socket had a BT Openreach VDSL interstitial plate. I had taken with me an ADSL Nation faceplate that I used at my previous residence but I didn't fit it in with the VDSL plate already in place, instead I hardwired using a krone punch down tool a cheap telephone extension cable to the landline phone at connections 2 & 5 and used a roughly 3 metre long cw1308 cable to connect B & A to the modem I was using. Phone line was clear, and ADSL speed was no different from the test socket, so was was seemingly fine with pretty consistent performance.
When in mid-2014 Plusnet raised their prices I was able to haggle a deal of them for VDSL broadband for an 18 month contract at a reduced rate. There really wasn't any need much for a BT technician to come around to my house other than to deliver the (ECI) VDSL2 modem, but he insisted in providing an extension of the master socket to where the previous ADSL modem was (Plusnet sent out a new router compatible with the service, their TG582n) where he cheekily reused the cw1308 cable I had as a xDSL extension! Speed tests never led up any higher much more than 33Mbps down and 8Mbps up despite BT's checker stating that up to 60Mbps down and 12.5Mbps up was possible but I wasn't too fussed as it was more than adequate for my needs.
So with my contract up with Plusnet and the VDSL service cost now at the standard Market 1 rate, I decided to look around considering I don't live too far from my local exchange and that despite it still being a 20CN exchange, Talk Talk had unbundled it (no other LLU operator though) I settled on the Co-op phone & broadband service as they were a Talk Talk network reseller. In saying that, the speeds being returned for my line were being given as low as 3.1Mbps down which seemed strange given the prior ADSL service on the line, but as long as an upload of roughly 1Mbps was obtained I didn't plan to be too worried.
So on the day of the changeover the Plusnet connection went down at 12:01 AM. In the morning I took out the VDSL ECI modem and Plusnet router and in its place a TP-Link TD-W8968 ADSL2+ modem whose user details were filled in from a letter the co-op sent me. The ADSL2+ service went live at around 11:30AM but from checking the router stats things looked slightly disappointing - the downstream attenuation was only 28db but the corresponding SNR margin was 12db and the speed was only 7.5Mbps. I though OK, the line likely needs trained anyway, and the upload speed connected at 950kbps. However in the early evening I noticed that the SNR fell down to just 3.1db, recovering shortly after midnight. Some brief testing with different modems showed that when the SNR fell, attempting to reconnect with the DSLAM meant reconnecting at a download speed of 5Mbps or even less though with an SNR of 12db - the exception was the TD-W8968 where if it was forced to reconnect it was able to hold on to speeds of around 6Mbps. I decided to leave in the previous Plusnet supplied router for their VDSL service which I'd now reconfigured for ADSL2+ and left it alone for a week. The following patterns were noticed...
* The sudden drop in the SNR occurs around 4.30pm to 5.30pm on weekdays until around midnight to 1.00am. At weekends the interference can come in much earlier in the day, usually around lunch time. I've done tests where I've had no other mains electric equipment in my home running other than the modem/router & the fridge with the former connected to the BT test socket, and there was no difference in the presence of the different SNR peaks so I can pretty much rule out anything in my home being responsible, including my heating and hot water timers.
* I've used the Plusnet TG582n in ADSL mode, the TP-Link TD-W8968 and an old Cable & Wireless ADSL2+ modem/router - of the three the TG582n gives the highest download sync speed at 8.2Mbps marginally ahead of the C&W, but was dropping the connection during the evening when the SNR ratio fell to 3-4db and was resyncing at around 4.8Mbps down with a 12db SNR. When the cause of the SNR drop disappears in the early hours of the morning, the SNR then rises up to over 19db! A manual resync at this time brings the download speed back to >8Mbps with a 12db SNR, until the interfering source comes again. During the period when the interference is present, the FEC errors for both download and upload skyrocket.
* Interestingly, during the times the download SNR drops, the upload SNR and speed is barely affected.
* I got my hands on an old BT Business Hub (2wire 2700hgv, came with the latest firmware so I couldn't really do much about that) and managed to get it set up for my line despite it being a little hassle when it comes to the MTU settings. It's upload speed connection is consistently 1Mbps, but even it has struggled to hold on to an 8Mbps download speed when the interference hits the download SNR margin when it falls to 4db or lower and a couple of times this week it has lost sync, resyncing at just over 5Mbps when it does.
I've came to the conclusion that I have a REIN problem. Where I live is a village in County Tyrone in a small housing estate next to a small Primary school. The times this interference comes on suggests that the source is from someone who works during the day on weekdays and possibly also has children at school. AM radio interference I think can be ruled out - the nearest transmitter site (BBC Enniskillen) is about 15 miles away LOS with an ERP no greater than 1kW, though there is another transmitter in a different direction slightly further away across the border in Co. Monaghan used by Spirit Radio which is on 549kHz with an ERP of 25kW.
I've attached screenshots below from the 2700hgv settings showing as many details as possible from it. With regards to the bitloading, when it resyncs in the presence of the interference there is no bitloading above bin no. 290, and those bins in the 200s are not as high as they are when it is synced without the interference present.
But even allowing for the interference, when it isn't there the maximum download sync rate looks rather low - according to my downstream attenuation figures which tend to hover at either 28 or 29db I should be able to get close to double the download speed potentially than what I am currently getting at the best of times! Something just doesn't seem quite right, yet Talk Talk's checkers tend to give rough figures of anything between 3-12Mbps depending on the day I check and I was only "guaranteed" a 3.1Mbps download speed. I'd rather try and sort the problem out myself if I can before contacting my ISP or getting Openreach involved - I have been looking at constructing an additional filter mentioned on the Wireless Waffle (http://www.wirelesswaffle.com/comments.php?y=12&m=02&entry=entry120211-055210) blog consisting of a choke and a low-pass filter to attenuate out-of-band signals where wideband interference could be causing my SNR drops, I'm just waiting on getting the appropriate inductors to build it as I have everything else. The drop line comes into the house via an underground duct though it's path out of here I'm not that sure of except to know which roadside cabinet it connects to.
I hope I've said plenty, I might have said too much! All help on this is appreciated. :cool:
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Additional attachments...
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Welcome to the Kitz forum.
Thank you for that comprehensive record of events. I am currently digesting the finer details but it does appear, from an initial read, that your assessment of the problem is correct.
The Openreach approach would be to install a BT80-RF3 before the NTE5 and to ensure that the latter is fitted with a Mk 3 SSFP.
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Welcome to the Kitz forum.
Thank you for that comprehensive record of events. I am currently digesting the finer details but it does appear, from an initial read, that your assessment of the problem is correct.
The Openreach approach would be to install a BT80-RF3 before the NTE5 and to ensure that the latter is fitted with a Mk 3 SSFP.
Thanks bcat!
I've decided to put back in the old Plusnet branded Technicolor TG582n this afternoon with the interference in place, currently syncing with stats of (for down) 5.258Mbps with an SNR of 12.1db and an attenuation of 27.5db, and also (for up) 1.02Mbps with an SNR of 13.4db and attenuation of 12.7db - I've attached a screen shot.
I'm not sure if it would be practical in my case for a BT80-RF3 to be fitted before the NTE5 - the master socket has a set of wires of orange & white and green & black with the orange and white connected to he NTE5. The back place is recessed into the wall of the living room with no other outlets (AC power, TV aerial point etc.) next to it. These network wires then disappear down a conduit for which I'm not 100% sure where it leads to - however my suspicion is that in then goes underground to a telegraph pole about 30 metres away - I'll have to check on this. However many of the other telephone lines going to this pole are overhead rather than underground, the ones overhead going to houses that were among the first built there in the 1950s whereas the home I'm in was constructed in the early 1980's to the best of my knowledge. It probably does not help that the estate is on a high elevation overlooking most of the rest of the village. The cabinet I'm connected to if following by road is nearly 500 metres away - slightly ironic as the straight line distance from the exchange to my home is 540 metres where my line length from the exchange is reckoned to be about 1.9km.
I actually have Mk2 SSFP that was originally in place when I moved in and that I used for the initial ADSL service which was then stupidly moved by the Openreach engineer (I think he was a contractor rather than actually from OR) for VDSL2 which on going to ADSL2+ I removed and replaced with the ADSLnation faceplace. From what I can see there is no significant difference in connection speed and reliability between the SSFP and the ADSLnation plate though the latter looks neater IMO.
Before I go out tomorrow morning I'll fire up DSLstats on the modem to leave running for at least 24 hours - that's the main reason I've changed the modem back to the Technicolor for now.
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I'm not sure if it would be practical in my case for a BT80-RF3 to be fitted before the NTE5 - the master socket has a set of wires of orange & white and green & black with the orange and white connected to he NTE5. The back place is recessed into the wall of the living room with no other outlets (AC power, TV aerial point etc.) next to it.
An ex-Openreach guy told me he used to just fit the circuit board from the BT80-RF3 housing, and could fit that inside the back box behind the NTE5.
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Before I go out tomorrow morning I'll fire up DSLstats on the modem to leave running for at least 24 hours - that's the main reason I've changed the modem back to the Technicolor for now.
That is an excellent decision. A collection of plots from 24 hours of monitoring may give us a clue as to "what's what".
Looking at the screen-scrape, the only information I can glean is that the remote device (MSAN or DSLAM) has line cards which make use of an Infineon chip set. (Not particularly relevant to your current problem.)
An ex-Openreach guy told me he used to just fit the circuit board from the BT80-RF3 housing, and could fit that inside the back box behind the NTE5.
I recall that either Black Sheep or Ezzer also suggested that trick . . . but I can't put my paws on the correct thread at the moment.
Just carefully pop the PCB out of the case and once it has been connected into the circuit, cut an appropriately sized rectangle from, say, an old margarine tub to use as an insulating layer between the PCB & the metal backing box.
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That was myself, B*Cat.
I have to agree it is aesthetically more pleasing than fixing the full housing next to the NTE. However, many, and I do mean many, an engineer have become a slight-cropper when using their test adaptors in the test socket to perform a PQT test. The RF80 throws the readings out somewhat, giving the false implication there's a fault on the circuit.
I myself was somewhat bemused when I first came across this practice, when the results shown on my PQT were strange to say the least (can't remember which parameters unfortunately ???). As a result of this, I nearly always remove the back-plate now to test. :)
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That was myself, B*Cat.
:thumbs:
I have to agree it is aesthetically more pleasing than fixing the full housing next to the NTE. However, many, and I do mean many, an engineer have become a slight-cropper when using their test adaptors in the test socket to perform a PQT test. The RF80 throws the readings out somewhat, giving the false implication there's a fault on the circuit.
I myself was somewhat bemused when I first came across this practice, when the results shown on my PQT were strange to say the least (can't remember which parameters unfortunately ???). As a result of this, I nearly always remove the back-plate now to test. :)
Crocodile clips onto the naked wires, I presume. :)
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Got it in one, sir. ;D
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I am not a big fan when having a BT80 RF3 connected before the NTE5 with a SSFP MK2 or MK3 installed as the attenuation will increase by 1.0dB it did for my 3 meters of internal wiring, so removed the BT80 RF3 and replaced it with a standard BT80 and just use the SSFP MK3 for RF filitering
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Before I go out tomorrow morning I'll fire up DSLstats on the modem to leave running for at least 24 hours - that's the main reason I've changed the modem back to the Technicolor for now.
That is an excellent decision. A collection of plots from 24 hours of monitoring may give us a clue as to "what's what".
AAARRGHH!!! There was a power cut at some point this afternoon which meant all the loggins from about 8am this morning were lost! >:(
I'll try the same again tomorrow. :fingers:
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Anyway, current connection stats are...
Downstream: 5341 kbps - SNRM 12.1db - attenuation 27.5db - interleave depth 32 - INP 1.08
Upstream: 1012 kbps - SNRM 13.2db - attenuation 12.7db - interleave depth 0 - INP 0.0
Current REIN (assumed) interference is active right now, as the downstream would be in the 8000+ kbps range otherwise
Bitloading graph attached. Now I didn't save a snapshot at the time, but I noticed that at around 8.30am this morning the bitloading graph was looking far healthier, with tones even active up to around number 470. Hopefully I remember to take one tomorrow morning.
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Could you also attach your Hlog and QLN?
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I can't seem to find it among the options. IIRC they aren't available on the TG582n through DSLstats but I could be wrong.
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I can't seem to find it among the options. IIRC they aren't available on the TG582n through DSLstats but I could be wrong.
That's correct. The Technicolor modems don't provide access to the QLN and HLog data.
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Just resynched a few minutes ago - current stats...
Downstream: 8190 kbps - SNRM 12.1db - attenuation 28.0db - interleave depth 128 - INP 2.70 - delay 14.6 ms
Upstream: 1020 kbps - SNRM 13.7db - attenuation 12.8db - interleave depth 0 - INP 0.0 - delay 1.13 ms
And the bitloading snapshot is attached.
I noticed that the interference came back between 7.30 am and 8.04am - someone using the offending device before going to work maybe? :-\
Also on the bitloading graph, tone 127 has zero bits - this likely corresponds to the 549kHz radio transmission I referenced earlier which is the strongest MW radio signal locally. However none of the other gaps seem obvious against AM radio transmissions.
Edit: speedtest.net result
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fwww.speedtest.net%2Fresult%2F5225755648.png&hash=5392a4f7a0d476ae0b9e58850bde73eba01b33ea)
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If you would please consider creating a MyDSLWebStats (https://www.mydslwebstats.co.uk/Container.htm) account, you can then automatically upload your circuit's data for us all to view.
As for tone number 127, the frequency is approximately 547 - 548 kHz. Looking at the usual reference (http://www.mediumwaveradio.com/uk.php), I do not find a match amongst the licensed broadcast transmitting stations . . .
(Assuming I've done the arithmetic correctly, a signal of approximately 547 - 548 kHz has a wavelength of approximately 547 - 548 metres! :D )
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I'll try and get an account at the website you mentioned later, possibly tomorrow. In the meantime I've still my stats running from this morning.
Re: Tone 127 - the station & transmitter in question isn't based in the UK - It comes from Spirit Radio in the Republic of Ireland. They have a network of low-ish power FM transmission in key towns and cities there plus they have a MW transmitter on 549kHz...
http://www.spiritradio.ie/on-air/where-can-i-listen/
Claimed coverage... https://www.google.com/maps/d/viewer?ll=53.173119%2C-6.020508&spn=5.631679%2C16.907959&msa=0&mid=zuFY3LoJqI6w.k5ATZ8FmA8l0
...the transmitter location is listed as Carrickroe (http://www.maplandia.com/ireland/north-east/monaghan/carrickroe/), which is in north Co. Monaghan less than 3 miles from the border with Northern Ireland & Co. Tyrone. Using Google Maps, the LOS distance is approx. 15 miles for me and Spirit Radio are apparently using an ERP of 25kW on that frequency. There's an unlicenced station in the same area also on MW called Radio Star County on 981kHz with a 1kW ERP, but it doesn't appear to be affecting the bitloading on tones 227 & 228 unlike the way Spirit does on 127.
Anyway I've taken an SNR snapshot of the last 12 hours. The drop in downstream SNR is pretty abrupt.
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That is a spectacular 8 dB decrease in the DS SNRM . . . a perfectly vertical, cliff-face of a drop, whereas the drop for the US SNRM appears to be a little under 1 dB. :o
Thank you for the details of those transmitters in the Republic. I was wondering if that might be the case, for radio waves do not respect any national boundary.
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Hi, I set up a MyDSLwebStats accounts in the wee hours this morning - my username is "sfarmer"
In the meantime I noticed that on the first abrupt dip in the downstream SNRM, the amount of FEC errors went from zero to, well I'm not sure how much is too much. :-\ However once the SNRM levels recovered, the FEC levels changed very little.
Interestingly while the mid-late afternoon SNRM dip happened again, it has now risen back up - whatever the offending device is it's stopped temporarily for now rather than being a constant interference plague until well after midnight. Might be time to try the 612kHz "REIN hunter" technique.
Attached is a graph showing the FEC just before the first SNRM drop yesterday afternoon, the last 24 hours of SNRM, and all snapshots taken a few minutes ago in a zip file.
:)
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Rather peculiar. ???
I wonder if WWWombat can spot anything untoward, please? :-\
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Hi - I had the TG582n disconnected for a short while this evening while I was testing a Huaewi HG612 I just got my hands on. Whilst I had some trouble configuring it for internet browsing it did connect to my ADSL service. This was during the period where the interference (which shows on my SNRM graph when synched at ~8Mbps download dropping from 12db to 4db), so I took advantage to grab a QLN, HLog & SNR per tone graph. Hopefully they might reveal more clues - it might be worth trying this again tomorrow when this source of interference gets turned off (from around 8am to 4pm)?
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Values with the 8db SNRM killing noise not present...
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Hmm . . . There does not seem to be anything obvious, to me. :-\
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On QLN I don't see any noise at the place of the bit-loading gap. However I see gaps on Hlog (lack of signal). It seems it is strange DSLAM operation (no interferences). DLSAM sometimes disables some tones. On the last tones you have crosstalk.
Best regards
konrado5
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From what I've been able to gather up to now...
* The DSLAM is setting the downstream SNRM at 12db regardless of the the speed it connects to at sync.
* The reason for the 12db setting appears to allow for a margin to compensate for a non-continuous source of interference that when present increases the noise level by approx 8db almost instantly. (Non-continuous in the sense of not being present 24/7 rather than having regular 'pulse' interference.) :'(
* The times this non-continuous interference source is present is during weekdays between roughly 7.15am to 8.15am and from some time starting between 4pm to 5pm until around 12am to 1am. There was one occasion this week when this interference was not present for several hours in the early evening, presumably because whatever is causing the interference was turned off at this time.
* If the modem syncs when this source of interference is not present, downstream sync is at approx. 8Mbps. When the interference is present downstream sync drops to around 5.1 to 5.4Mbps. In the case of the former when the non-continuous interference becomes present the SNRM drops to 4db. The the latter case when the non-continuous interference stops the SNRM increases to 19-20db.
* Other than the +/- 8db SNR jump, the downstream SNR remains very consistent with no real changes over a 24 hour period. :cool:
* The upstream SNRM is also fairly consistent - it is slightly affected by the non-continuous interference with a roughly 1db increase in noise. It is syncing continuously and reliably at 1Mbps. :cool:
* From observing my QLN graphs both with this non-continuous interference being present and not being present, and comparing them to other ADSL users on MDWS, two things stick out for me - first, my noise floor is fairly flat & consistent with no major "spikes" with it being roughly -110db up to around tone 250, then falling smoothly down to about -123db at tone 400 before rising again to about -113db at tone 500. Second, despite the noise floor being fairly smooth, it appears that my line is rather noisy in the sense that other MDWS ADSL stats indicate a general noise floor (excluding noise spikes) quieter than this, in many cases down to -140db. It appears that this noise is wideband - however what is noticeable is that this noise is at its highest in the downstream below 1.1MHz - while the ADSL service I have is an ADSL2+ LLU product, my exchange is otherwise a 20CN with a standard ADSL1 service through BT Wholesale. Possibly the case that I have significant cross-talk problems? :( :(
* Looking at the Hlog graphs, I may have came to the conclusion that the MW broadcast station on 549kHz is not significantly causing interference to tone 127 and that the reason for this tone having no bitload is a co-incidence. A MW broadcast normally has a sideband on each side of the carrier between 4.5kHz to 7kHz wide and would surely interfere with adjacent tones if the radio signal caused interference, but it's not the case here. I don't really know the reason why some bit tones missing while adjacent tones are perfectly fine, I can only think that something on the line is causing very narrow notches on specific frequencies. Again I don't see these narrow notches on other ADSL Hlog graphs on MDWS, or at least not to the same extent.
* My downstream attenuation is 28db. According to the maximum speed calculator on site here at www.kitz.co.uk/adsl/max_speed_calc.php it gives the following results...
* Downstream attenuation: 28db
* Approx line length: 2km
* dslMAX (20CN): 8128kbps - IP Profile: 7150 kbps
* BT 21CN WBC & adsl2+: 16512kbps - IP Profile: 14564 kbps
* adsl2+ (LLU): 16512 kbps - Throughput: 14613kbps
...and also another calculator for estimating ADSL line speed... http://coolwebhome.co.uk/calc/index.php?param=RG4gODE5MCBEbiAyOCBEbiAxMi4xIERuIDI=#res
It appears to me that my phone line is seriously hobbled for ADSL speeds where even at the best sync speeds it's achieving only about half the downstream throughput it is potentially capable of. :-\
* I've attached a screen grab of the Broadband Exchange & Line Checker - because I'm on an LLU it doesn't give back more accurate stats like estimated FTTC speeds but when my phone number was with Plusnet (and hence on BT's network) it was returning almost the same results for LOS & road distance from my exchange (Fintona, NIFIN).
Now I'm wondering what to do next as I've two separate issues to overcome, namely combating the non-continuous interference source, and IMO the generally noisy line levels. The former would seem to be slightly easier to deal with than the latter but would almost certainly need Openreach involved. :-\ :-\
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Looking on mdws I see you have no bitswaps....is this something you have checked your equipment for....If you have,I would suggest contacting your ISP and eventually getting a "lift and shift"
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Looking on mdws I see you have no bitswaps....is this something you have checked your equipment for....If you have,I would suggest contacting your ISP and eventually getting a "lift and shift"
Bitswaps do appear to be happening with me - for whatever reason they aren't showing up on mdws?
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Well I've tried using both the BT80A RF3 filter and the one I linked to in the wireless waffle blog in my opening post and neither have been effective in suppressing the non-continious noise source within the last 24 hours it has been present. >:(
I'd love to get a hold of this f**king device that is causing the noise floor to degrade as it's clearly impacting on my potential downstream sync speeds (not that they are amazing otherwise but they are at least quite usable) and I'd be pretty certain it would be the same for many close by as well though how many I don't know, could be less than a handful or a few hundred. Those on FTTC packages probably aren't likely to notice (like I had once done) as much as those with ADSL, many of whom probably don't realise or care that their speeds could be better.
Is it time to give up on what I can do myself and speak to my ISP to try and possibly get Openreach to investigate?
Edit: I was just off the phone to my ISP (Phone Co-op) and in the meantime they've rest the SNRM margin to 9db. I'll see how this works out.
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That will be the target SNRM which has been set to 9 dB.
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That will be the target SNRM which has been set to 9 dB.
Yes, you're correct. :-[
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I have your SNRM, CRC/min, FEC/min and ES/hour plots configured to view via MDWS.
In the immediate past 24 hours I see that there have been five resynchronisation events logged. The one at 1416 hours was due to your ISP/CP resetting the target SNRM. The most recent event at 2156 hours has resulted in a 1 dB increase in the US SNRM and no change to the DS SNRM.
Your circuit is behaving in a most peculiar fashion and, to be perfectly honest, I currently have no idea what is occurring. ???
It is unfortunate that your modem/router only provides a subset of the full data that can be viewed via MDWS.
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I think it is crosstalk issue, because I don't see any narrow dips on QLN. Single disabled tones are related to DSLAM settings because QLN doesn't show any dips on these toens and Hlog show nothing (no signal).
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Hi B*Cat.
I can explain two of the resynchs around this time last night as these were done by myself - the first one at around a quarter to midnight was fitting in a BT80A RF3 filter between the DSL wall socket & the DSL port on the TG582n, but it made no difference to any visible stats. The next resync at around 1:05am (by this time the non-continuous interference went to sleep for the night) was removing the BT80a RF3 and replacing it with the Wireless Waffle blog suggestion for the low-pass filter & common-mode choke, evidence that this wasn't doing the trick came at 12:46pm when the SNR fell again to 4db.
However the resync that took place at just before 10pm this evening wasn't done by me.
At this point I decided to go outdoors with a MW radio on 612kHz (and a few kilohertz either side) to see if I could track the source of interference if it was nearby me - the only time this was noticed was when I held the radio next to the plastic ducting on the telegraph pole that takes my line underground to my house and could simply be put down to proximity, nothing really out of the ordinary - there did seem to be a very faint rise in background noise when going between the houses that are fed overhead rather than underground, but that again IMO could be just residual noise from DSL along the lines and/or faint electrical noise. Certainly I've seen far worse destructive interference to MW & LW radio signals from EMI particularly about 0.5 miles away where even the stronger signals get lost into mush or are heavily affected. Among the houses where the phone lines are fed underground to the premises' there was no sign of raised noise levels at all.
My theory at the moment is that the interference from a device (probably a television or set-top box or their respective power supplies) is managing to couple its way into the telephone line on the offending premises which is feeding back into the junction box on the telegraph pole or possibly beyond which in turn is degrading the noise levels on lines in close proximity to it.
What I'll try and do within the next 24 hours is to get the HG612 I have set up properly where if I can't use it in router mode I'll try bridge mode so I can keep it on the line to enable more detailed stats to be present.
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Thank you for that explanation. :)
Your postulation, as to a defective device radiating spurious RF noise, which then couples into its local telephone pair and, eventually, your own circuit, is certainly a possibility. Also, as Konrado5 has suggested, the possibility of cross-talk should also be considered.
The details on how to use an Huawei HG612 as a two port modem/router is available in the Kitz Wiki (http://wiki.kitz.co.uk/index.php/Huawei_HG612). It was some years ago, when I last used one in that fashion. (It is possible to configure a HG612 to operate, in ADSL mode, as either a modem/router or as a pure bridge.)
Once you have finished making adjustments to the circuit, I would then like to see how it behaves over a complete uninterrupted 24 hours period.
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HG612 now all set up and running, feeding to MDWS. Stats from the past three hours were me just fiddling around a bit. Can't promise that I'll have it up for the next 24 hours straight as some other work might lead to having plugs switched off/exchanged, but I'll keep it in mind. :angel:
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Thank you. :)
We now have the full set of ADSL2+ circuit graphs to consider and I'm still scratching my head! :-\
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I had the connection down just after 10am today for a few minutes as I was changing a few wires including moving the WAP upstairs (linked by Cat5e cable from HG612) and adding a 10/100 8 port TP-Link hub for the entertainment element of the living room.
Regardless of anything else, would it be safe to say I have a REIN problem? Yesterday seen the target SNRM margin of 9db go from an ongoing SNR of 9.4-9.6db go right down to 0.9-1.0db while the non-continuous interference was present - despite the poor SNR level, the HG612 held on without too much apparent difficulty - only an Android tablet game reported "slow connection" a couple of times and that was it.
Now noticeable is the attainable speed levels on the downstream - without the non-continuous interference at the ~9db SNR level it's hitting 11.1 to 11.4Mbps, but when the interference hits to take the SNR down to ~1db the attainable speed drops down to about 7.0-7.1Mbps, i.e. a drop of more than a third & 4Mbps. :no: OTOH Upstream attainable speed only changes a few kilobits here and there.
I suspect that regardless of any continuous noise (from the likes of crosstalk etc.) from looking at the noise floor of the QLN graphs, getting this non-continuous interference eliminated would allow me to sync with a lower target SNRM and bring my downstream speed to a more expected level. :cool:
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Yes, I agree with your conclusion.
On checking the status of your circuit (at 1644 hours) I see that the interferer has just become active, once again, at 1641 hours.
The drops in SNRM are mirrored by massive increases in FECs. However the number of CRC are trivial (one, one and thirteen, i.e. fifteen over the last 24 hour period) as are the number of Errored Seconds (four recorded, one each in four separate hours over the last 24 hour period).
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The irony is that the amount of FEC corrections at present is now significantly lower than when the target SNRM was set at 12db.
Looking at the times on Thursday 7th & Saturday 9th before the 9db target SNRM was set, the downstream FEC figures were hitting over half a million. After the change however at worst this figure is now at four figures and since the return of the interference this afternoon, it's been no higher than 620 a minute.
On early Saturday afternoon before I got my ISP to change the target SNRM, I managed to manually change the target SNRM through DSLstats to 6db just as a test and I was able to get a downstream attainable data rate of over 13Mbps, which starts looking a lot better for the line attenuation rate.
Now to look at how to get this REIN sorted. The technical person at the Co-op phone & broadband I spoke to sounded quite knowledgeable and friendly to talk to but given the trouble tracking the source of REIN in the first place I'm not sure wherever it would be even worth my while chasing it up on to Openreach and risk getting hit with a callout fee. What I'll probably do some day this week is to switch off all electric in my home and use the 2wire HGV2700v powered via a USB portable battery as the modem & router connected at the master socket and monitor the stats on the laptop from around 4pm until the interference becomes present - with the mains electric killed during that time that should absolutely rule out anything on my premises. :angel:
Thanks to yourself B*cat and also to konrado5 for your knowledge and time to help me understand the problem I'm having better. than before :)
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I would suggest that you try a different approach.
We can see, quite clearly, when the interferer is present and absent. So when the interference is absent, I would then use a suitable radio to go all over your own property and see what is normal. Switching power supplies, compact fluorescent lights, TFT displays, etc, all radiate some RF. So see what is normal. In particular see what can be heard adjacent to the cable that connects the modem to the filter, adjacent to the telephone line, etc.
Then wait until the interference re-appears. Quickly re-check around your property, remembering what you experienced when the interferer was absent. If you can detect the interference by the the modem - filter link cable, check adjacent to the incoming telephone line.
Analyse the above and if, as you have previously suggested, it might be something that is radiating into a telephone line elsewhere and then coupling into your telephone line in the vicinity of the DP. Think old television, think old Sky box . . .
What about your immediate environment? Are you miles away from anyone else, a sheep farm halfway up that hill over there? Is there a local enthusiast of arc-welding who repairs metal objects in the barn, down the lane? Are you so situated that there is a good line of sight between you and Grimbledon Down? Is there an RAF base, currently used by the USAF, nearby? An experimental radar installation? A 132 kV to 11 kV substation?
Accurate notes of your observations, coupled with your knowledge of your topography, is likely to be the only way that leads to an eventual successful conclusion.
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Hi B*cat. I'll try what you're suggesting within the next few days. One thing that has became clear is that although the interference is sort of predictable in terms of what times they appear on for the day of the week, it can't be timed to the exact minute on a predictable basis.
I'm 99% certain that the problem is not caused by something in my own premises. I occasionally indulge in AM radio DXing with indoor loops and I know that raised background noise levels are the bane of this hobby. There are two devices that I have which give off wideband hash interference, one is a SMPS that came with an Android "TV Box" and another is an old-ish Openbox S11 satellite receiver whose power supply looks dodgy anyway - I don't really use the former (I only need to get it set up again before giving it back to my brother) while the latter I only use now for helping align satellite dishes as I've now got a satellite receiver whose power supply behaves itself. It probably goes without saying, but in my experience a lot of cheap Chinese electronics & power supplies are poor at EMI suppression, if not outright dodgy at times.
When I was outside last Saturday when the noise was present on the line, I did have a portable radio which when I went to the telegraph pole my line is on where I held the radio next to a drop line that was in a duct before it goes underground - on that occasion the noise became stronger and the signal meter on the radio was registering it - of course that can just be noise from the ADSL service itself so I'll need to check between the noise being present and not being there to see a change I guess.
At the master socket I have a filter faceplace that I bought around four years ago - I think it was made by ADSL nation, but it's the same fascia as the filter on the right of the image below. I originally bought it when I was living in a flat and had a ADSL2+ Sky LLU, where it gave nearly a 1Mb downstream improvement over the filter supplied with the Sagem F@st2504n. Between the filter and the modem is a length of Cat5e cable - overkill perhaps, but it was readily available at the time. Blue twisted pair is used for POTS and green twisted pair for xDSL on the IDC connectors on the filter, which go to respective BT431 & RJ45 sockets. From the RJ45 socket is a short (30cm) CW1308 lead with RJ45 and RJ11 plugs on each end.
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fwww.increasebroadbandspeed.co.uk%2Fwp-content%2Fuploads%2F2012%2F01%2Fi-plate-versus-ADSL-faceplate.jpg&hash=a30648d8764d064ab4a6efaf00e5614b2724106f)
My local environment is in a small housing estate in a village in the rural Co. Tyrone countryside. My home doesn't have a farm attached to it(!) though there is a field less than 100 metres away where some newborn lambs and ewes are prancing around at present. :angel: As I mentioned previously, there is a primary school just behind my back garden - though the time patterns of the interference would suggest that the offending interference is unlikely to come from there. There is a woodworks shop about 200 metres down the hill from myself, but again the timing of the interference would suggest it isn't from there. I can't think of anyone in the near vicinity that might use something like a welding torch. There isn't an electric substation right next to me, but it might be worth finding out where the nearest one is, I probably just haven't noticed it.
There are no armed forces camps in the local area (the nearest ones are about 35 miles away each, one a small RAF camp and another an Irish Army camp in Co. Donegal), the nearest radar installation - if it is currently in use - would be at an airport (St. Angelo) about 13 miles away. There are no broadcast transmitters in the local area, though I can see the Brougher Mountain TV & Radio transmitting station from an upstairs window. There is a 2G Vodafone mast approx 350 metres away in a straight line - the next nearest is a Vodafone 3G/4G & O2 2G/3G/4G mast at roughly 900 metres.
I'll report back in due course. :police:
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All read and understood. I'm sure we all will be interested in any discoveries that you make. :)
Whatever the source of the interference, it is clearly something that is turned on and off . . . :-\
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Haven't been able to run a thorough test yet, but one thing I have noticed is that if I fall back to ADSL1 or ADSL2 mode (i.e. not ADSL2+) the corresponding SNR drop is approx. 6db as opposed to 8-8.5db for ADSL2+
Also the interference wasn't present yesterday for much of the afternoon despite it being there the previous Saturdays - presumably the sunny weather at the time provided a good excuse for the offending item not to be on.
If I was to take a guess at the problem, I'm going to go for a domestic appliance in either a TV or a dodgy set-top box. But again I'll need to do my own investigating first.
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OK, this took a little longer than planned but I'm back to looking at the interference source.
I previously said that I as 99% certain that the source of interference was not in my house. I'm now raising that to 99.9% - I've just tested starting from switching everything electrical off in the house including the fridge, central heating & smoke alarms with only the HG612 router being powered (the laptop to monitor the stats being on its battery). The modem suddenly went gaga when I was switching off at the switch board that sent CRC rates briefly skyrocketing, it resynchronised on ADSL1 only for whatever reason. A further manual resync brought it back to ADSL2+.
After a couple of minutes of allowing the modem to settle, I started switching things back on one-by-one and observed the SNR margin when these devices were powered back on. The variation of SNR margin from the modem being the only electric powered device to everything that was powered back on previously was only 0.3db for upstream and 0.1db for downstream.
I'm heading away this afternoon so I'll leave the laptop (now plugged in) running to feed MDWS and when I come back, the interference should be there. I'll repeat the process then that I've done this morning switching devices off and bringing them back on - should it also give a negligible variation of SNR margin, then my confidence that the REIN interference is not coming from my home will be 99.99%.
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...and BOOM! The SNR margin has just dropped without me doing anything from 9.9db to 1db downstream and 14.2db to 13.2db upstream.
Will do the second test later, but I reckon that a call to my ISP for a suspected REIN problem is in order. I'll let the HG612 keep running to see if it can hold the 1db SNR margin.
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What's a little odd is that the change doesn't seem to have resulted in errors, unless your router/modem doesn't report errors. There's a sudden increase in FECs, otherwise I'm be starting to wonder if the change in NM was actually real.
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What's a little odd is that the change doesn't seem to have resulted in errors, unless your router/modem doesn't report errors. There's a sudden increase in FECs, otherwise I'm be starting to wonder if the change in NM was actually real.
Yeah, when the SNR margin destructing interference is present the FECs shoot right up into their thousands, though there are few or no CRC or HEC.
I didn't get a chance to test the SNR margin when the interference was on yesterday, hopefully I'll get a chance this evening.
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Is there any reason you are not uploading your stats 24/7....I can't seem to get a good handle on your stats without this; and by the way FEC's in the thousands is not really important, if they were in the 10's of thousands then there MAY be a problem.
Ian
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Would moving back to a VDSL connection be an easy fix?
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Is there any reason you are not uploading your stats 24/7....I can't seem to get a good handle on your stats without this; and by the way FEC's in the thousands is not really important, if they were in the 10's of thousands then there MAY be a problem.
Ian
Hi Ian. I don't leave my computer running 24/7 which is why the stats aren't up then. As for the FEC's, it is getting up to the tens of thousands if not hundreds of thousands IIRC, but I'll need to wait until the interference is back again before I demonstrate that.
Baa!
Would moving back to a VDSL connection be an easy fix?
Probably, but the interferer on the line would likely still be there? :-\
I'm quite happy with ADSL2+ provided I could get something like 12Mb/s down and 1Mb/s up, 38Mb/s down is a bit wasted on me for the extra expense it would incur. If this proposed 18/2 VDSL2 trial is something I might get offered, I'd be interested though.
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Well this was interesting, earlier this morning I was doing a resync on the line and for whatever reason it went into VDSL2 mode! I didn't think this was possible unless you were specifically connected at the cabinet D-side?
Anyway, it threw up the following stats...
Stats recorded 11 May 2016 11:21:23
DSLAM/MSAN type: BDCM:0xa48c / v0xa48c
Modem/router firmware: AnnexA version - A2pv6C038m.d24j
DSL mode: VDSL2 Profile 17a
Status: Showtime
Uptime: 7 min 35 sec
Resyncs: 0 (since 11 May 2016 11:17:57)
Downstream Upstream
Line attenuation (dB): 50.9 0.0
Signal attenuation (dB): Not available on VDSL2
Connection speed (kbps): 8065 8519
SNR margin (dB): 7.1 6.0
Power (dBm): 12.1 7.6
Interleave depth: 4 4
INP: 46.00 50.00
G.INP: Enabled Enabled
Vectoring status: 5 (VECT_UNCONFIGURED)
RSCorr/RS (%): 0.0004 0.0000
RSUnCorr/RS (%): 0.0000 0.0000
ES/hour: 0 0
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 8652 Kbps, Downstream rate = 6188 Kbps
Bearer: 0, Upstream rate = 8519 Kbps, Downstream rate = 8065 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 7.1 6.0
Attn(dB): 50.9 0.0
Pwr(dBm): 12.1 7.6
VDSL2 framing
Bearer 0
MSGc: -6 -6
B: 146 146
M: 1 1
T: 0 0
R: 16 16
S: 0.5780 0.5472
L: 2256 2383
D: 4 4
I: 163 163
N: 163 163
Q: 4 4
V: 1 1
RxQueue: 28 32
TxQueue: 7 8
G.INP Framing: 18 18
G.INP lookback: 7 8
RRC bits: 24 24
Bearer 1
MSGc: 90 58
B: 0 0
M: 2 2
T: 2 2
R: 16 16
S: 10.6667 16.0000
L: 24 16
D: 1 1
I: 32 32
N: 32 32
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 0
OHFErr: 0 0
RS: 3136460 3325923
RSCorr: 11 1
RSUnCorr: 0 0
Bearer 1
OHF: 28389 28440
OHFErr: 0 0
RS: 169961 113761
RSCorr: 0 0
RSUnCorr: 0 0
Retransmit Counters
rtx_tx: 13309 0
rtx_c: 8 0
rtx_uc: 0 0
G.INP Counters
LEFTRS: 0 0
minEFTR: 8063 8521
errFreeBits: 56083 58851
Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 6671061 0
Data Cells: 969 0
Drop Cells: 0
Bit Errors: 0 0
Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0
ES: 82 94
SES: 55 0
UAS: 1087 1032
AS: 456
Bearer 0
INP: 46.00 50.00
INPRein: 1.00 1.00
delay: 0 0
PER: 0.00 0.00
OR: 0.01 0.01
AgR: 8106.54 8562.89
Bearer 1
INP: 2.50 4.00
INPRein: 2.50 4.00
delay: 0 0
PER: 16.06 16.06
OR: 47.81 31.87
AgR: 47.81 31.87
Bitswap: 20/20 19/19
Total time = 1 days 19 hours 56 min 6 sec
FEC: 5881921 1
CRC: 2447 129
ES: 82 94
SES: 55 0
UAS: 1087 1032
LOS: 5 0
LOF: 45 0
LOM: 0 0
Latest 15 minutes time = 11 min 6 sec
FEC: 168 1
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 126 126
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 60 60
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 19 hours 56 min 6 sec
FEC: 1643629 1
CRC: 445 15
ES: 10 8
SES: 10 0
UAS: 253 243
LOS: 1 0
LOF: 9 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 2337462 0
CRC: 1 5
ES: 1 5
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 7 min 35 sec
FEC: 11 1
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 8645 Kbps, Downstream rate = 6188 Kbps
Bearer: 0, Upstream rate = 8519 Kbps, Downstream rate = 8065 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)
Medley Phase (Final) Band Plan
US: (871,1205) (1972,2706)
DS: (33,859) (1216,1961) (2793,3597)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 8645 kbps 6188 kbps
Actual Aggregate Tx Power: 7.6 dBm 12.1 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 46.2 47.7 52.7 N/A N/A 47.1 51.7 62.8
Signal Attenuation(dB): N/A 47.4 53.4 N/A N/A 47.1 51.5 63.0
SNR Margin(dB): N/A 6.1 6.0 N/A N/A 7.1 7.1 7.1
TX Power(dBm): N/A 2.7 5.9 N/A N/A 8.9 7.7 4.4
# xdslcmd info --vectoring
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 8652 Kbps, Downstream rate = 6188 Kbps
Bearer: 0, Upstream rate = 8519 Kbps, Downstream rate = 8065 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Vectoring state: 5
VCE MAC Address: 0:0:0:0:0:0
Total error samples Ethernet pkts sent: 0
Total error samples Ethernet pkts discarded: 0
Total error samples statuses sent: 0
Total error samples statuses discarded: 0
# Line attenuation (dB) U0 U1 U2 U3 U4 D1 D2 D3
11 May 2016 11:18:24 46.2 47.7 52.7 N/A N/A 47.1 51.7 62.8
Signal attenuation (dB) U0 U1 U2 U3 U4 D1 D2 D3
11 May 2016 11:18:24 N/A 47.3 53.2 N/A N/A 47.1 51.5 63.0
11 May 2016 11:19:24 N/A 47.2 53.4 N/A N/A 47.1 51.5 63.0
11 May 2016 11:20:23 N/A 47.3 53.2 N/A N/A 47.1 51.5 63.0
11 May 2016 11:21:23 N/A 47.3 53.3 N/A N/A 47.1 51.5 63.0
11 May 2016 11:22:23 N/A 47.1 53.3 N/A N/A 47.1 51.5 63.0
11 May 2016 11:23:23 N/A 47.4 53.4 N/A N/A 47.1 51.5 63.0
11 May 2016 11:24:23 N/A 47.3 53.3 N/A N/A 47.1 51.5 63.0
11 May 2016 11:26:23 N/A 47.3 53.4 N/A N/A 47.1 51.5 63.0
11 May 2016 11:27:23 N/A 47.2 53.3 N/A N/A 47.1 51.5 63.0
11 May 2016 11:28:23 N/A 47.2 53.4 N/A N/A 47.1 51.5 63.0
...It couldn't possibly be that Openreach are experimenting with VDSL2 from the exchange, or that I caught a crossed wire somewhere, perhaps both? Feel free to make use of those stats what you will.
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Openreach are not allowed to run FTTC from the exchange- doing so would breach the UK Network Access Frequency Plan.
If you put your number in https://www.dslchecker.bt.com/ what does it say - specifically the text about jumpers under the main table?
If you had fibre before, I am guessing your cabinet is not very busy so Openreach switched off the FTTC service but left the hardware attached (i.e. if you were moving home and the new owners wanted fibre) - either that or they now plan to reallocate the port.
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Hi, I had a VDSL2 service from Plusnet before I migrated to the Phone Co-op ADSL2+ service. Putting my phone number into the BT checker won't work as it's now on an LLU circuit (MFP?), and using the address checker gave no clues to jumpers on the line.
Edit: Thing about the DP point seems to be irrelevant.
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DP = Distribution Point (for instance a telegraph pole)
Some places such as flats may have DP's inside the buildings.
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The VDSL2 signal appearing on the circuit will have to be the a result of a fault -- probably contact with another VDSL2 enabled circuit.
When a G.Dmt/ADSL2/ADSL2+ circuit is converted to VDSL2, a low-pass filter will then be present between the DLSAM & the E-side cable to stop the high frequency xDSL signals travelling back towards the exchange and, more importantly, to prevent the E-side cable acting as a bridging tap across the pair.
When a VDSL2 circuit is converted to G.Dmt/ADSL2/ADSL2+ the tie-pairs to the fibre cabinet are disconnected in the PCP and a plain D-side to E-side jumper is reinstated. That step has to be performed, otherwise the G.Dmt/ADSL2/ADSL2+ signal from the exchange will be blocked by the low-pass filter in the fibre cabinet and not reach the EU.
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Thanks for the explanation burakkucat. :cool:
BTW I'll leave the laptop running overnight for uploading stats to MWDS for anyone looking to have a peek - my current FEC error rate is around 1200-1400 per minute.
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I'm going to have to retire the MDWS uploads for now unfortunately, however I did the same appliance test with the interference present that I did on Sunday when there was no interference and again there was no shift in the downstream (1.3db) or upstream (13.8-14db) SNR margins. I reckon a call to my ISP to suggest a REIN problem is in due course as I can pretty much rule out something in my home causing this problem.
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It's six months since I last posted here, and in the end I've kind of given up on it as whatever is causing the SNR to drop would seem like an impossible task to trace. I did over the summer hold out that when the neighbours were on holiday that the interference would stop but alas it didn't. Also the RF environment is quite a noisy one so the 612 kHz test doesn't be that useful :(
Thanks to everyone who helped me on this thread, sadly I don't know how many people are suffering from this interference as it could be just myself and a few others on the DP or in the worst case scenario it could be everyone connected to the same cabinet as me! I'll settle with 8Mb down & 1Mb up that I currently have which is adequate.