Kitz Forum
Broadband Related => ADSL Issues => Topic started by: Bigmac77 on June 15, 2012, 08:37:22 PM
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Hi, this is my first post here please be gentle with me. I'm having ongoing problems with my broadband, I won't go into a huge amount of detail or this will be a huge post but some detail is necessary so here goes.
I started with download speed problems (speed went down to 0.13Mbps) a few months ago, since then I have used the BT forum to contact the moderators and have had three engineers visit. The first fixed a HR fault, (things temporarily improved) the second replaced the line from the local distribution point to my house (again things temporarily improved) and the third put me onto a different pair all the way from the distribution point to the exchange. The last engineer has improved my broadband but it's still not 100%. My problem now is that my router will not hold sync for more than a day and everytime it re-syncs it keeps my profile lower than it should be. I've tried 2 BT Homehub 2's these performed the worst, dropping the connection many times a day. I've tried a 2Wire 2701, it performed quite well but the sync speed was the lowest and eventually it started loosing sync like the Homehub's. I am now trying a Netgear DG834G v3, it syncs well at nearly 4800 Kbps (my line has an attenuation of 52 dB) but looses sync around midnight. I also have a DG834G v4 but have not tried it yet.
Around 10pm everyday the noise margin drops to around zero.
Here is a graph from router stats, do I have a fault or is it something else?
I also have a shilded RJ45 cable running from a NTE-2005 faceplate from ADSL nation. Any ideas?
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Here is a graph up to 2230 hrs, the router resyncs after 2220.
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Hello BigM and welcome to the Kitz forum. :)
Ideally we would like to see at least a full 24 hours Routerstats graph to be able to see how your line's performance varies. The fact that the modem renegotiates sync when the SNRM has dropped to zero comes as no surprise.
What would be useful, if you could arrange to do it, would be to initiate a modem re-sync between 1000 - 1400 hours (i.e. in daylight) and as soon as the connection is established, take note of both of the DS & US SNRM, Sync speed and Attenuation values. Please do this as soon as the modem has resynchronised with the DSLAM/MSAN as that will be the only way we can deduce your current target SNRM.
As you probably appreciate, the SNRM can vary over the 24 hour period. During the hours of darkness, there can be significant RFI induced into the xDSL pair and, thus, the SNRM is depressed.
Finally, a few simple questions. To which exchange is your line connected? To what broadband service are you subscribed?
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Are those graphs more or less the same every day? - the following assumptions are made on the fact that they are:-
4800 is a good sync for 52db
Theres a lot of SNRM fluctuation but its still within what would be classed as normal variation by BT on a 52db line.
It looks like it could be EMI and therefore needs a higher SNRM that 6dB to keep the line stable.
.. or you could try some investigative work to see if you can spot any sign of EMI/REIN (http://www.kitz.co.uk/adsl/rein.htm).
Asking your ISP to increase your target SNRM will keep the line stable but you will loose a bit of sync speed.
.. or you could keep it sync'd as is it now.. and hopefully the SNR will increase tomorrow but if you ever sync that line before 9pm then it will likely drop again come later in the evenings.. at some point the DLM should kick in and auto increase the target SNRM anyhow.
>>> Around 10pm everyday the noise margin drops to around zero.... but looses sync around midnight.
What happened @ around 9.15?
Does your street lights come on?
>>> Warning - while you were typing a new reply has been posted. You may wish to review your post.
B*cat beat me to it.. but still posting this anyhow.
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Thanks for the replies. Yes the graphs are pretty much the same every day. Everyday now for the last three weeks with all the routers I've tried the same pattern occurs. Between 8am and 11am the router will resync with the exchange at 4500 Kbps +/- 300 Kbps then it will hold stable until around 9:30 - 11:30 the router will resync again at lower speed and hold this over night until the process starts over again. I'm surprised I've not had my SNR increased to 9 dB but I'm sure my current target remains at 6 dB.
I live in a very rural area there are no street lights within a mile but there are some lights nearer to the exchange as its in the middle of the Amlwch which is a small town.
My exchange is Amlwch code WNAML and I'm on BT option 2.
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>> Between 8am and 11am the router will resync with the exchange at 4500 Kbps
Can we see the graph at that time please...
Is this resync automatic or manual.. if auto I find that a bit strange, normally with REIN, the additional noise will cease and the line will hold just showing an increase in SNRM.
>> no street lights within a mile
Streetlights was the first thing that came into my head because of the time.. but it could be anything in your home (or neighbours) that comes on at around that time each day.
>> I'm surprised I've not had my SNR increased to 9 dB but I'm sure my current target remains at 6 dB.
According from the info in the graph at around 22.25, it certainly looks like your Target SNR is 6dB atm, although how long that will last for Im not sure:(
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Once the routers are plugged in I don't touch them any resync is automatic, nothing in my house comes on around 9-10pm to make sure I turned everything off in my home at the switchboard (except the sockets that the router is plugged into) and it makes no difference. Where I live there are five other houses the nearest is currently being renovated/rebuilt and they've not got any power into the property yet, the others are a distance away form the phone line over 50 metres could they be emitting some set of REIN from that distance?
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>> resync is automatic,
Thank you - would like to see what is happening to the SNRM at these times from the graph.
>> others are a distance away form the phone line over 50 metres could they be emitting some set of REIN from that distance
Its not impossible, we have seen cases where faulty tvs/sterios have knocked out a whole street.
Really do need to see a whole days graph now please to get a bigger picture.
(b*cat has already asked for those, so perhaps I shouldnt have jumped in too quick :blush:)
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I'm currently gathering data will post back soon.
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I'm currently gathering data will post back soon.
Thank you. We look forward to examining any graphs. :)
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I switched over to the DG834g v4 that I had on Saturday just too see how it performed. I am amazed by the performance now, over a 24 hr period it has produced the graph below far more stable than anything I had seen before.
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Here is another graph from router stats. Any opinions on the condition of my line greatfully received.
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I switched over to the DG834g v4 that I had on Saturday just too see how it performed. I am amazed by the performance now, over a 24 hr period it has produced the graph below far more stable than anything I had seen before.
Looking at that graph in isolation, I can see nothing to be concerned about. When using the DG834Gv4, it appears to be a very well behaved line. With regards to "hours of darkness" RFI and its effect on your SNRM, a swing of 2 dB is really quite good! :)
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Here is another graph from router stats. Any opinions on the condition of my line greatfully received.
Graphs of that type get me well confused, so I shall refrain from commenting. I have every confidence that A.N.Other will shortly be passing by and will offer up an analysis for our edification. ;)
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Thanks, I think it looks ok but as you say it is in isolation. What other graphs from routerstats are helpful in checking the quality of a line?
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>> Here is another graph from router stats. Any opinions on the condition of my line greatfully received.
At first glance looks like theres a wee bit of noise around tone 60 (radio transmitter?/ is internal wiring ok?).. tone 64 is the pilot tone so thats not in use any how. SNR is okish in comparison, so whatever caused the blip, line has recovered. Later tones show some bins with few bits, rather than smooth drop off, but thats not too unusual on longer lines.
The bit loading is a bit juttery from that graph, but if its been taken after the router has been up a while, then bitswapping can cause that effect.
Bit loading in the earlier tones more ot less follows the (real) SNR but again showing signs of bitswapping probably having occured.
The real SNR is a bit bumpy but nothing of too major concern (check internal wiring)- again wondering if that line has been up for a while and bitswapping has caused increased power output.
I dont know what the actual line stats are from that graph, but I cant see anything major - comparing it with the SNRM fluctuations in the first graph.. it doesnt look too bad overall. Line definitely seems in much better condition when using the DG834gv4.
When looking at bitloading graphs its always nice to have a graph after first boot up, then compare with one a day later, as its hard to say for sure with just the one as bit swapping can distort things a bit.
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Thanks Kitz, the bits & attenuation plot is the first 24 hours since the router was plugged in.
Bear with me on this, you refer to internal wiring in your reply, when the last BT engineer was here after he had finished he plugged in a black box which which carried out a number of test on my line and ADSL connection I watched as the device declared that the line had passed all the tests. The BT line comes into my utility room extension loft space and connects to a length of phone cable the electrician fitted (house was renovated including a rewire 2 years ago) the phone cable then runs through a duct into the main part of the house to the NTE5 BT socket. The duct carries all the twin and earth feeds from my consumer unit plus the central heating control wires. Could this be the cause of my problems?
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The internal wiring was just a standard suggestion to see if any improvements could be made.. It wasn't a definite diagnosis as i couldn't see anything glaringly wrong from the graphs provided.
Thanks for confirming that the bit loading graph was after 24 hrs. After comparing with a graph showing a shift of snrm then it is likey/possible that the spikes are due to bitswapping that could/would have occurred over the past day.... And you have to look at a larger picture.
For example if u just look at the tones in region 60 in the graph you could say something wrong there... But then look at the real snr which is fine. So it probably means at some point there was a burst type noise at those tones and bit swapping has done its job to keep the line stable. The noise burst could have been for a fraction of a second, or could have been longer.. its impossible to say from just the one graph.
I'm accessing via mobile device so its harder to put inline links, but theres a section on the main site which explains bit loading and bit swapping if u want to know more
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Edited to add link
http://www.kitz.co.uk/adsl/adsl_technology.htm#bit_loading
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My main concern is do I have a fault on my line? Yes I have found a router that works, will hold sync and produce a decent SNR graph but it's a router no longer available if something happens to this one unless I stock up on v4 DG834g's from ebay I'll be back to square one.
With regard to my previous post about the proximity of my house wiring to the phone line the only way to tell will probably be to move the NTE5 faceplate to the end of BT's incoming line and see if it makes a difference. I hate loft insulation.
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The DG834Gv4 uses a Broadcom BCM6348 chipset, and it's most probable that other routers with the same chipset will have similar ADSL performance, so I don't think you need worry about stocking up with routers. There's a list of several routers with Broadcom chipsets here. (http://wiki.kitz.co.uk/index.php?title=Broadcom_CLI)
The performance you're getting with the DG834Gv4 is quite reasonable for your rather long line, so there's no indication of any line fault (unless it's an intermittent one). I wouldn't change anything more now, but continue to monitor the noise margin, etc. as you are doing.
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With regard to my previous post about the proximity of my house wiring to the phone line the only way to tell will probably be to move the NTE5 faceplate to the end of BT's incoming line and see if it makes a difference.
Ideally, I would prefer that the xDSL line runs via a separate route and has a significant spacing from any parallel mains wiring. If you had a suitable length of 2-, 4- or 6-core CW1308 specification cable, you could perhaps leave the NTE5/A in situ and just run it from a temporary feed, bypassing the current cable that is in close proximity to the mains wiring?
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I can't run a cable via another route because of the layout of the house but I can move the NTE5 box. Where can I buy cw1308 cable from?
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. . . Where can I buy cw1308 cable from?
Any of the usual suspects! ::)
Amazon market place (https://www.amazon.co.uk), eBay shops (http://my.ebay.co.uk), ADSL Nation (http://www.adslnation.com/phpapps/catalog/product_info.php?products_id=96), Clarity (http://www.clarity.it), run-IT-direct (http://www.run-it-direct.co.uk/searchresults.php) and Solwise (http://www.solwise.co.uk/telesun-telephone-cable.htm), to name a few.
I have a reel of three-pair CW13008 specification cable (green, blue and orange pairs), 150 m length, that I recall buying from a small supplier in the Amazon Market Place.
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umm this has to be said.. and to make sure Im understanding properly... the nte5 is BT's demarcation point and therefore any wiring/cabling before that point is bts responsibility.
When I said internal wiring I meant the usual stuff such as plugging the router into the master socket, checking extension sockets, filters and removal of the bell wire. These simple things can ofter improve line stability.
It looked like you had a problem:- your earlier routerstats graph certainly showed something weird was happening later on in the evening. But since using the netgear, the graphs that have come back so far show that although there is some slight SNRM fluctuations and bitswapping, these would appear to be within normal parameters for a line of your length.
Unless Ive missed it, we havent seen any actual line stats since the netgear has been on the line.. Is the line syncing at a better rate? Have their been any other changes in the line stats and it would also be helpful if we could see the error counts. (eg RS/CRC and errored seconds)
Since using the netgear have the evening dropouts stopped?
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I'm 100% sure there is no problem with my wiring, there is no bell wire or extension sockets, I've tried 5 different filters all plugged into the test socket on the NTE5, I have changed the RJ11 - RJ11 cable from the filter to the router, I've tried it with and without my Panasonic DECT phone all made no difference to the previous four routers. The DG834g v4 has performed better but last night it did what all the others had done and lowered the sync speed at around 10.30. I'll post up some error counts later.
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Ok I have some stats and graphs.
Downstream
Noise Margin: 7.5 dB
Connection Rate: 3776 Kbps
Line Attenuation: 54.0 dB
Power: 18.7 dBm
Max Rate: 4064 Kbps
SuperFrames: 4490961
SF (CRC) Errors: 359
Reed Solomon: 152692686
RS Corrected: 128479
RS Un-Corrected: 7580
HEC: 216
Errored Seconds: 656
Severe ES: 108
Interleave Depth: 16
Bitswaps: 0
Upstream
Noise Margin: 20.0 dB
Connection Rate: 448 Kbps
Line Attenuation: 31.5 dB
Power: 11.8 dBm
Max Rate: 1084 Kbps
SuperFrames: 4491025
SF (CRC) Errors: 0
Reed Solomon: 38173712
RS Corrected: 0
RS Un-Corrected: 0
HEC: 0
Errored Seconds: 0
Severe ES: 0
Interleave Depth: 4
Bitswaps: 0
This represents 21 hours of data since the netgear did a resync last night.
The resync can be clearly seen on the graphs. Please can you help me interperate these graphs.
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Immediately after I reset the router yesterday the noise margin was 6dB. The sync was 4138 Kbps and last night after it lost connection it re-synced at 3776Kbps at an SNR of 6dB again.
Are there any other graphs which would be of benefit to post up?
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>>> Please can you help me interperate these graphs.
Sometime at around 13.30 you line picked up an additional bit of noise but only about 0.5dB and this can easily be tollerated.
At about 9.30pm the line started to became increasingly noisy until the SRNM got so low, and the build up of errors so high, that the line eventually dropped out.
Unfortunately despite having a respite for a few days, those graphs are back to indicating some sort of EMI. :(
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RS Corrected (FEC type errors (http://www.kitz.co.uk/adsl/error_correction.htm#FEC)) are when theres some noise on the line, but the its coping fine due to interleaving and error correction working as it should.
RS Uncorrected (CRC type errors (http://www.kitz.co.uk/adsl/error_correction.htm#CRC)) is when data hasnt been recovered from interleaving and data has had to be re-transmitted.
Too many CRCs in a short time span can trigger more serious errors such as Errored Seconds (http://www.kitz.co.uk/adsl/linestats_errors.htm#ES) and SES.. and too many of those cause the line to drop.
On graph 2 you can see a build up of FECs till about 3pm when all goes quiet. But then just after 10pm it starts again. The steep drop is because the line has lost sync and obviously the counters have reset.
On graph 3 you can see that things were fine up until about 10pm, when the line is producing lots of CRCs - its when the line gets too noisy and equivalent of the router saying "sorry didnt hear that- can you say it again" due to lots of background noise.
Looking at the overall picture something happens at about 9.30ish and the line starts to get increasingly noisy, at first the line copes due to FEC, then CRCs start happening, but then it gets to the point where it looks like there a sharp noise burst and it cant cope anymore and drops out.
After resync theres still some background noise but it no longer increases and has reached a plateau.
At about 8am the next morning we see a sharp increase in CRCs indicating something similar with noise but not quite as bad or for as long.
Im trying to thing of something that would trgger that type of EMI - increasing buzz over 1/2 hr then a quick burst and back to a background but more stable buzz. Perhaps the other guys can suggest something, but nothing immediately comes to mind for me what this could be.
Is there anything electrical in your house which follows this type of daily pattern.. um water heaters, something that uses overnight power-saving etc... I think you said you have no street lights nearby which would normally be my first guess, but what about external/motion sensor lighting.
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Having tried my best, I cannot come up with anything to account for that RFI. (I assume that the antique milking machine in Farmer Giles' cow-shed is not used at those times?)
I just cannot feel "happy" knowing that the internal feed to the NTE5/A travels through ducting with cables carrying relatively high current mains supply . . . I would probably make a temporary disconnection at the point where the CW1308 cable (which disappears into the ducting) is joined to the external feed cable, attach a modem/router (powered by a battery pack -- as sheddyian (http://forum.kitz.co.uk/index.php/topic,11326.msg219183.html)'s experiment) and connect it to my laptop computer, running on its battery. Switch off the electricity at the main switch and monitor the line during the crucial time period(s). That should provide some crucial information.
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>>> I just cannot feel "happy" knowing that the internal feed to the NTE5/A travels through ducting with cables carrying relatively high current mains supply
Oh I fully understand where you are coming from B*cat and if the EU does some tinkering then its on their own heads.. as long as we have warned about the demarcation point and how anything before that point belongs to BT and shouldnt be touched, then we have done our job too ;)
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Thanks for looking at the graphs and interpreting them for me. Re the NTE5 faceplate I am aware that I should not fiddle with it but it's in my house and I'm competent when it comes to wiring so I would hopefully not cause myself any problems if I were to try moving it and I understand that on my head be it.
I have nothing in my house that comes on at the time the problems really start to kick in, but they do occur when daylight is starting to fade and if I were just looking at the graphs I would say it must be some sort of lighting but as I said there are no such lights in my area. The heating is not currently on in my house and we have nothing that comes on over night. Outside the house there are two lights which operate on PIR's but I can and have isolated them. I have a CCTV system which switches to IR overnight but I have tried with this turned off and it made no difference.
I have tuned a radio to 612khz after 10pm and I get very good reception of a foreign language radio station.
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I went and did some investigative work with my radio last night conditions were not the best (strong wind) but I was definitely when I was stood next to the pole from which all the phone cables run. When the weather is better I'll try again.
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Been out again tonight if anybody saw me they would think I was nuts. Presumably if I'm right next to the local DP I should be able here here the signal coming down the phone lines? Apart from this I could detect nothing but how far should I be checking? To the cabinet serving me? To the exchange?
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Ezzer used to be our resident expert when it came to getting out the radio.. but hes now on the other side of the pond.
Unfortunately this is not an area where I have much knowledge, but Im sure one of the other guys will be able to help.
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Maybe I could not pick up anything because there was nothing to pick up. Last nights graph does not look too bad.
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Agreed. That looks quite normal. :)