Kitz Forum
Broadband Related => ADSL Issues => Topic started by: matthewcl375 on March 08, 2013, 04:00:57 PM
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Hey everyone :) This is my first post on Kitz ;D
I have an issue with my ADSL Max connection that I can't seem to get to the bottom of: my broadband from Tesco (advertised as up to 8Mbps) had been giving a throughput of up to 7Mbps (875KBps) until 26th January. On this date we started getting disconnections every few minutes, and later found that this was a line fault causing noise on the phone line. On the 27th an engineer came out and installed a new line to the street pole across the road, fixing the noise problem.
After he had gone, we got a sync of around 4.7Mbps, this was with a Target Noise Margin of 15db due to the previous line fault. Over time this Noise Margin has gone down and we are now on a Target of 9db, getting a sync of 6.8Mbps.
The problem is this: According to the Kitz ADSL Line Checker, we are only 0.2Km from the exchange by road, and I have been told by others that this should give a sync of 8128 or 7616 (depending on the presence of interleaving) even with a 9 or 12db Target Noise Margin. This seems to show that our connection is underperforming. I have included line stats below:
DSL Type: ITU-T G.992.1
Bandwidth (Up/Down) [kbps/kbps]: 448 / 6.880
Data Transferred (Sent/Received) [MB/MB]: 8,44 / 66,22
Output Power (Up/Down) [dBm]: 11,9 / 13,8
Line Attenuation (Up/Down) [dB]: 6,0 / 6,0
SN Margin (Up/Down) [dB]: 23,0 / 9,1
I would really appreciate any help with this. I and a few others are struggling to get to the bottom of why this line is not performing optimally :(
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Hi and welcome
Certainly, if those attenuation figures are correct, you should be connecting at the maximum speed for your service. The figures suggest that there is some constant level of interference which is causing the reduced performance.
I suggest that you install a monitoring program to see how the SNR margin varies over time. Depending on your router, you could install Routerstats (or Routerstats-Lite) (http://www.vwlowen.co.uk/internet/files.htm) (which works with most routers) or rs-ux /rs-w (http://rsux.plainroad.me.uk) if you have a compatible router. If you run it preferably for 24 hours and copy the SNR margin graph here, it may help to understand what the problem is.
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Thank you for the quick reply!
I forgot to mention I have already been running routerstats since this problem occurred, right now its showing a steady 9db to 9.1db all day and all night which is confusing to say the least...
I have also eliminated my cordless phone as a source of noise, there's nothing else in the house which I can think could cause it, we don't have any extensions plugged into the phone line, filter is plugged into test socket etc. etc.
In light of this I really don't see how noise could be causing a problem, unless its noise from neighbouring houses... Others have suggested I may be on a banded profile, a bad joint in the new line, or that there could be an issue exchange-end.
Do any of these sound likely?
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Others have suggested I may be on a banded profile, a bad joint in the new line, or that there could be an issue exchange-end.
If you were on a banded profile, the SNR margin would be higher, so it's not that. A bad joint in the line would cause the SNR margin to jump about far more, so it's not likely to be that.
It's difficult to imagine any other explanation than a constant level of interference. This would imply something electrical which runs continuously. It could be a malfunctioning or badly designed power supply for some kind of electronic equipment, or a local factory or pumping station, or something of that nature. It could also be some malfunctioning equipment at the exchange.
Perhaps the first thing to do is to switch off everything in your house except the computer and router, and see if the SNR margin increases. If it does, then it would appear that the problem is internal, and you would need to identify the culprit by a process of elimination. If not, then the problem is external, and that will be much harder to identify.
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@Roseway, I will certainly try that the next time I can (i.e. when no one else is in the house), another thing I am considering is plugging in my old extension wiring and then relocating the router to the upstairs phone socket, to eliminate any noise from the room the router is currently in. If that gives a higher sync/SNR Margin then that would show it is something in that room causing noise.
@Everyone What I didn't mention is that I am moving to BT Broadband over 21CN, on around the 25th March. They estimate speeds of between 16 and 19.5Mbps. Is there a good chance this will fix any issues at the exchange end of the line?
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The upgrade to 21CN-WBC involves switching your line over to new equipment (from a DSLAM to an MSAN) so if the DSLAM is the problem then the change would fix it, but I'm not sure how likely that is.
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So, if it's an exchange problem that could fix it, Openreach tested the new line after it was installed and it seemed good to them, so must either be noise or exchange issues...
Eliminating noise can be tricky :-\ Think it's worth trying the router in the upstairs extension socket?
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Something is weird with those stats.
Output power is only 13.8 dBm. If that line was running at its maximum, i'd expect it to be in the 18-19dBm region.
However such a short line will have the highest PSD mask which will cause some power cut back, but I would expect the router to try & give more because its not reaching any where near the full potential. Have you got another router to try? Because your output power is so low, this is stopping you from reaching maximum speeds.
Normally I would assume it was some sort of banded profile, but then you'd expect the SNRM to be much higher and not at a constant 9dB.
A constant 9dB SNRm from RStats would suggest there isnt an obvious noise issue. (unless it is constant noise as suggested by roseway)
Im wondering if the DLM has done something weird on that line during the period of the line fault. As the owner of a short line myself I know the 20CN DLM does strange things on very short lines... and I often found myself with some very weird profiles that were hard to get rid of without ISP & BTw intervention. The stuck profiles I got most often was 2Mb, but iirc I did have a couple there were around 4.5 Mb mark after occurrences such as power cuts.
If it were my line I would be requesting a full line reset from my ISP. However if that line is due to go 21CN next week... a line reset should occur then anyhow.
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Kitz, thank you for your very helpful reply :)
The only other router I have is a BT Home Hub (version 1), and that gave output power of 11.5db up, 9.5db down, giving a lower sync of 5664Kbps ???
I would agree with you about noise, also in the last few weeks the target SNR margin has been dropping steadily from 15db which points to there being no noise issues on the line, I also ran a quiet line test showing the same...
The only thing I can think of it being is something DLM has done, noise at the exchange end, or maybe a bad joint/fault in the new line that was installed, though from the quiet line test it sounds just like a normal line to me
I would add that before the line fault, going by the throughput I was seeing we were on a 7.15Mbps profile, which would show our line was getting the full speed, which would point to the current issue being DLM related, or maybe a fixed setting at the exchange.
Others have mentioned that the SN Margin should be a lot higher and that I don't have any 'spare SNR' to give higher speeds, does this sound right?
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I'm posting from a mobile device ATM so can't C&P or post links easily. excuse the formatting too.
As rebards to the higher SNR.. Normally I would say yes that is the case..... However like me I think you are suffering from one of the frequent problems that I also saw when on maxdsl that would affect my own line and only seems to affect the very shortest of lines. The DLM seems to seems to flip its lid and do very strange things.
I've just managed to find one of my old posts to show you what I mean. In such cases the DLM seems to set a fixed rate SNRM..... And cuts back the power instead.
As you can see, in my case after a power outage, what it did was set the SNRM at 6db... And reduce my output power. I'd copy the stats if I could, but for now youll have to look at the link to see what I mean.
http://forum.kitz.co.uk/index.php/topic,1637.0.html
I'm pretty sure you are experiencing the wonderful joys of being on a maxdsl short line.
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Had a read through your thread, there are some differences i.e. your router was reporting 8128 whilst DLM reported another value... with mine both are reporting the same sync and apparently I don't have spare SNR...
What was your output power supposed to be before it dropped?
I've got various questions going through my mind right now, like 'why would DLM reduce my output power' and 'how come the engineer didn't reset the line after he had fitted the new line from the pole'?
Sorry if I'm asking too many questions here, this thread seems to explain these kind of problems well for anyone else reading this:
http://www.skyuser.co.uk/forum/sky-dlm/47557-why-dlm-falls-short-mark.html (http://www.skyuser.co.uk/forum/sky-dlm/47557-why-dlm-falls-short-mark.html)
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Perhaps with only being able to link to the thread, you missed the stats in that particular thread which is what I was trying to show. All the stuff that happened afterwards was whilst trying to get the original problem sorted. I went through numerous 'stuck bRAS' problems during that period. The router reporting 8128, and the DLM another figure, didnt occur until later on
If you look closely at the first post stats, you will see I was experiencing the low Output power which is what you are displaying now:-
These were the stats taken from my router after the power outage.
Statistics Downstream Upstream
Line Rate 736 576
Noise Margin 6.8 dB 6.0 dB
Line Attenuation 7.0 dB 7.0 dB
Output Power 11.9 dBm 13.1 dBm
Someone looking at those stats without noticing the power output would think that line is syncing as fast as it possibly can because there is no spare SNRM above 6dB.
It seems that somehow the DLM was able to throttle back the power to 11.9 dBm... meaning that I didnt have any surplus SNRM at all. (default is 6dB)
For comparison, these are some stats showing what the line was usually like
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fwww.kitz.co.uk%2Frouters%2Fimages%2FDMT3.gif&hash=07191cadb97331bc680cc4af8b5244daf77ffe2c)
Notice full sync speed, normal tx power in the region of 18dBm, and surplus SNRM over the default 6dB.
Re the sky thread, Sky uses a totally different (new) DLM system. Im not aware that BT 20CN uses ASSIA for powercut back to control DLM.
What is beyond doubt though is that very short lines do and always have suffered badly when it comes to stuck profiles and odd things happening with the BT 20CN DLM system. Its the reason why I got off it asap and was glad to go LLU adsl2+ (about 2 weeks after that thread).
For some reason, something is holding back your output power, which is why your sync speed is now so low. The fact that there is no surplus SNRM doesnt hold relevance - nor follow the 'normal' rules - in your particular case.
Your line needs a total reset.
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Kitz thanks for the reply,
What I did find helpful about the Sky thread was that it shows how a reduced output power leads to a reduced amount of 'spare' SNR, which in turn leads to a sub-optimal sync, it was connecting those dots which was confusing me before ;)
Whilst I'm not moving to an LLU ISP (I'm moving to 21CN BT Broadband) I assume that the migration of ISP will trigger a line reset? I was also thinking isn't a slight reduction of output power sometimes necessary to reduce crosstalk in densely populated areas?
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>> how a reduced output power leads to a reduced amount of 'spare' SNR, which in turn leads to a sub-optimal sync,
Yes :)
>> I'm moving to 21CN BT Broadband)
Yes hopefully it should. Its a different DLM system so you should start afresh.
>> I was also thinking isn't a slight reduction of output power sometimes necessary to reduce crosstalk in densely populated areas?
Normally BT use PSD masks on adsl1/adsl2+ to help prevent cross-talk. iirc theres 4 different profiles in use depending upon the length of your line. Theres not much info out there (or at least wasnt last time I looked) on what these profiles are, but afaik the masks are applied on certain tones/frequencies... so that when those particular tones are fully loaded, it ensures that short lines dont drown out neighbouring long length lines.*
VDSL also use PSD masks but in a slightly different way.
*by neighbouring I dont mean as in the same are, but lines that may be on the same MSAN, or say cables bundled nearby from the exchange on the way to the cabs.
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Ah, that makes perfect sense, as you said I would be on the highest of those profiles...
Another difference between your problem and mine is that with mine, after the fault my target snr was put at 15db, as well as the possible (likely) reduction of output power that occurred :-\ Also yours recovered pretty quick whereas my output power has been like that since the fault at the end of January
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For completeness and the entire 'back story', I provide the links to Matt's four threads in the ThinkBroadband fora --
Slow internet/low IP profile/high noise margin on Tesco (http://forums.thinkbroadband.com/unhappiness/f/4204903-slow-internetlow-ip-profilehigh-noise-margin-on-tesco.html)
Slow internet/noise margin questions on Tesco Broadband (http://forums.thinkbroadband.com/unhappiness/f/4209886-slow-internetnoise-margin-questions-on-tesco-broadband.html)
Reduced sync speeds on Tesco Broadband (http://forums.thinkbroadband.com/unhappiness/t/4211761-reduced-sync-speeds-on-tesco-broadband.html)
Will switching ISP get me a better sync? (http://forums.thinkbroadband.com/btsupplier/t/4217717-will-switching-isp-get-me-a-better-sync.html)
I did read each and every post, more or less in 'real time', as they were made 'over there'. As to be expected, things did start to get a little bit confusing, what with certain people just wanting to 'have their say'. :-X
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>>> Another difference between your problem and mine is that with mine, after the fault my target snr was put at 15db,
Your fault had been present for a while, therefore during the fault period the DLM will have had chance to go through all the profiles - ending up with the highest - in an attempt to stabilise your line.
My problem occured after just one brief power outage, therefore it will recover quicker - my line wasnt unstable enough to go any further than interleaving and was still on the default 6dB SNRM profile.
The only point I was trying to make in this thread.. is that for some reason something seems to trigger a cut back of power to fit the SRNM ie leaving no surplus SNR margin like you would normally see. I'd only dug out that thread so that you could see my stats also showing SNRm at the same rate set on the DLM, with power cut restricting the speed.
Bear in mind the thread I pointed to you was just one of many instances over a 3 year period when my line would do silly things that the DLM is just not supposed to do. Its why I got so fed up of the BTw maxdsl profiling system and jumped off it as soon as I possibly could.
Switching to adsl2+ should hopefully start a new retrain on your line.
Why this didnt happen after your line fault was repaired is another matter, and one that I would be pushing my ISP for now, if it wasnt for the fact that you are moving over to a new product in a few days.
>>>> I provide the links to Matt's four threads in the ThinkBroadband fora
I hadnt realised that it had been topic of conversation over there too.. I chipped in purely because I noticed the power cut back which will without doubt be what is restricting your speed.
Unfort I just dont have time atm to read through those threads, but there are some very knowledgeable people over there who are also capable of providing correct information, it may be just that no-one noticed the power cut back. I only knew to look for it because Ive seen it happen before on very short lines.
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Kitz that is true, I am surprised that I and others didn't notice the output power stats earlier on, I think we were so busy looking at the SN Margin and Sync Speed to notice
Also, not to start a forum war here :-[ but a lot of people on TBB did just want to have their say and many times I didn't get concise answers, whereas here you have all been very helpful and straight to the point, I didn't have to keep asking for clarification or getting 3+ conflicting opinions every time I asked a question which only confused me more ::)
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TBH the thing that really should have been done is a full retrain of your line after the fault was fixed rather than you having to go through the long slow process of waiting for the DLM to slowly go back down through each profile. From the information provided its obvious that this hasn't been done.
Most of the 'decent' ISPs should have been able to have arranged this for you after a line fault fix.
I just had a very quick look at one of the TBB threads, and although I didn't get to the end - it's getting late and bedtime for me - I was surprised at how long this had been going on.
I'm not quite sure if it's worth perusing a retrain now since you are soon to go adsl2+ and by the time you get through to someone to action your request it may be too late anyhow. I'm not quite sure are you staying with tesco or going elsewhere?
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I'm not quite sure are you staying with tesco or going elsewhere?
I can quickly answer that before I, too, go and find my warm and sleepy spot! :sleep:
On the 25th of this month we are having BT Broadband activated . . .
From the very first line of the post by Matt, at the start of his fourth thread over at the TBB fora. ;)
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That's right! It's with BT and I have just phoned them now, order is all good and the MAC code was according to the CS staff 'not needed now' which I take to mean they have entered it/stored it on their system and it is valid :) However she also thought I was on cable, presumably because my ISP is Cable and Wireless :D
I have little doubt that the migration will fix a lot of the slow line problems we have been experiencing over the last month or so :)
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Good luck and I hope it all goes well for you :)
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Thanks Kitz, I was wondering if you would know what kind of speeds I should see on ADSL2+ in the unlikely event of my downstream output power not rising and staying near 13.8?
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>>> in the unlikely event of my downstream output power not rising and staying near 13.8?
no idea TBH, but obviously no where near the full 24Mbps you should be near getting.
Mine now runs at about 18/19dBm on a 3dB SNRM
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I have a niggling feeling it will improve ;) but we shall wait and see, as I say it's getting activated monday, will report back then ;)
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OK, BT Broadband was activated earlier this afternoon, my stats are below, output power has increased but not syncing at full speed YET:
Connection Information
Line state: Connected
Connection time: 0 days, 01:22:12
Downstream: 15.7 Mbps
Upstream: 888.9 Kbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 9.3 dB / 12.0 dB
Line attenuation (Down/Up): 6.2 dB / 3.3 dB
Output power (Down/Up): 20.0 dBm / 10.6 dBm
FEC Events (Down/Up): 14 / 0
CRC Events (Down/Up): 0 / 32
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 0 / 11
Error Seconds (Local/Remote): 4 / 0
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9.3 dB SNRM is taking away some of your sync speed (default is 6 dB)... and it also appears that the line is interleaved, which will also be costing you some sync speed.
Edited to add.
May be worth monitoring the line with Routerstats to check that the SNRM isnt fluctuating.
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Would the margin not be expected to be higher than that, given the very, very near proximity to the Exchange ?? I usually see them up at 18dB when they're so close ?? :-\
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I have no idea why the SNR Margin isn't higher, this is a problem I've seen before, Kitz suggested that my output power was too low to supply that extra SNRM, but now it's gone up to 20dbM I can't see what's causing it ???
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Would the margin not be expected to be higher than that, given the very, very near proximity to the Exchange ?? I usually see them up at 18dB when they're so close ?? :-\
The weird thing though BS, the line isn't syncing (yet) to full potential. It's only syncing at 15.7 Mbps, yet it's running at full 20dBm power. I'd expect the power to run at about 18dbm.
My attenuation is slightly higher, and I can sync higher than that. Iirc when I first went on adsl2 + my sync was around 18 / 19 mbps when interleaved on default 6db SNRM. Moving to FAST increased my sync quite a lot.. to 24 mbps with 3db SNRm. Harder to compare now cause I'm on annex m.
The line also seems to be displaying some errored seconds. But not many... But worth keeping an eye on.
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I do believe the errored secs are from where the Internet light on the Hub went out for about half a minute, this was right after it came online for the first time and haven't seen it do that since
It's really confusing, this underperformance :S But hey, this is the fastest home broadband I've ever used so..
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Okay, that is possible.
I think the best thing you can do for now is monitor that line... And hopefully get SNRm down and interleaving switched off. We need to ensure it's stable though first. Strictly speaking it should be capable of more... But we need to see what's gong on first and a period of time with RouterStats should help us in this respect.
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Unfortunately Router Stats isn't compatible with the Home Hub 3 :(
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Unfortunately Router Stats isn't compatible with the Home Hub 3 :(
Not even the Lite version? :o (How I detest that American spelling. >:( )
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Unfortunately it would appear it doesn't. May be worth trying this suggestion for the v2.
http://vwlowen.m3ezw.co.uk/phpBB3/viewtopic.php?f=1&t=301&p=1440&hilit=+Homehub+3#p1440
Alternatively, use a router that works with routerstats.?
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That doesn't seem to work :-\ Oh well...
Had a couple of re-syncs so far, these are my current stats, as can be seen upstream sync has improved quite a bit, but looks like some Downstream sync has been sacrificed in the process:
ADSL Line Status
Connection Information
Line state: Connected
Connection time: 0 days, 00:10:41
Downstream: 15.99 Mbps
Upstream: 1.13 Mbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 9.0 dB / 6.2 dB
Line attenuation (Down/Up): 6.2 dB / 3.3 dB
Output power (Down/Up): 20.1 dBm / 11.5 dBm
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these are my current stats, as can be seen upstream sync has improved quite a bit, but looks like some Downstream sync has been sacrificed in the process:
Upstream and downstream have completely separated frequencies (subchannels), so each channel ( ie up/down) dont encroach on each other and are independent. Its only when moving to annex_M that downstream is sacrificed for upstream.
Your upstream power has now slightly increased which is why you are possibly getting the higher upstream.
As regards to downstream, its normal for it to fluctuate during the course of the day... because SNR fluctuates. This is normal and to be expected. You could sync at say mid-day and then try a re-sync a few minutes later and it will be different. It is very seldom that your downstream sync will ever be exactly the same.
It may aid understanding to read How to interpret your adsl line stats (http://www.kitz.co.uk/adsl/linestats.htm). In particular:-
~ What is SNR? (http://www.kitz.co.uk/adsl/linestats.htm#SNR)
~ What is SNR Margin? (http://www.kitz.co.uk/adsl/linestats.htm#SNR_Margin)
~ What is Target SNR Margin? (http://www.kitz.co.uk/adsl/linestats.htm#target_SNR)
There does appear to be something a tad weird going on with that line because it doesnt appear to be performing to full potential yet... However its still within the training phase and could settle down... and you should give it time to do so.
If it was me, Id personally be swapping the router for one that works with Routerstats, RS-W, or DMT tool. ;)
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I also noted that the Target SNR Margin upstream has been pulled down to 6db now, no idea why the DLM can't do the same for downstream and give me a better sync
Yeah easier said than done in my case since I don't own the router or pay for the broadband :-\
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Yeah easier said than done in my case since I don't own the router or pay for the broadband :-\
I wasn't aware that you weren't the account holder. :-\
What about the router you used on tesco net, and iirc you did have another router too. I can't recall now what these were as this is a quick reply before bed. What were these and can they be used to get some decent monitoring.
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Nearly off to bed myself ::)
Errm I have the router from Tesco, the TG582n, which worked fine Broadband-wise, apart from the occassional reboot when things got a bit too hot to handle
The only other one is the BT Home Hub 1, which is pretty much useless broadband-wise, last time I plugged it in it gave a crappy sync and forced my IP Profile down to 4.5Mbps :(
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The tg582n should work fine on adsl2+. I use one myself as I find it stable with good sync rates for a short line. It also works fine with routerstats. I stand mine on its side and it keeps reasonably cool.
The 2wire home hubs on the other hand - whilst they seem to be very good on long lines - from my own experience are not so good for short lines :(
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Just thinking 'out loud', atm . . . an Huawei HG612, unlocked with the Asbo-firmware, connected to a Beattie HH3.0 should allow even the most obsessive Eagle to gather an over-abundance of line statistics. ::)
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I'd like to try the tg582n on this connection, but I think it would be best to leave it till the end of the 10 day training before plugging it in, you know just in case it makes the sync plummet or some other oddity :D
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Well, I've been put on fast path, let's see how it turns out:
ADSL Line Status
Connection Information
Line state: Connected
Connection time: 0 days, 03:03:48
Downstream: 16.06 Mbps
Upstream: 1.156 Mbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 9.0 dB / 6.5 dB
Line attenuation (Down/Up): 6.2 dB / 3.3 dB
Output power (Down/Up): 19.9 dBm / 11.7 dBm
FEC Events (Down/Up): 0 / 0
CRC Events (Down/Up): 0 / 6
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 0 / 6
Error Seconds (Local/Remote): 8 / 76
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Just to keep y'all posted, I believe my Target SN Margin has dropped to 6db:
Connection Information
Line state: Connected
Connection time: 0 days, 03:09:12
Downstream: 17.09 Mbps
Upstream: 1.125 Mbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 7.2 dB / 6.9 dB
Line attenuation (Down/Up): 6.2 dB / 3.3 dB
Output power (Down/Up): 20.0 dBm / 11.3 dBm
FEC Events (Down/Up): 0 / 0
CRC Events (Down/Up): 0 / 0
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 0 / 0
Error Seconds (Local/Remote): 53 / 121
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To know for sure you'd need to check immediately after a resync.
Im not saying that this is the case with your line, but its possible that
(a) Its still 9dB SNRM and youve lost 2dB of SNR. OR
(b) Its now 6db SNRM and youve gained 1.2 dB of SNR.
The lack of CRCs is good even though its only been up for 3 hrs.
It looks like the Err/Secs may be cumulative and not reset each sync.
Based on that one snapshot FAST mode is fine otherwise Id expect to see some CRCs... but would need to be monitored properly.
Still think the line is way under performing for a 6dB atten.... but we are still in the waiting period.
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Edited to add
Whilst on the subject of 6dB attenuation... I confess I dont know much about the HH3 , but I suspect it may well be that the HH3 is one of those routers that reports the down attenuation at 300 kHz, (due to the figure not having changed when moving between adsl1 and adsl2+) ~ See attenuation (http://www.kitz.co.uk/adsl/linestats.htm#attenuation)
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Well, I'm now on what seems to be a 4.5db Target NM, the hub's been up since the end of the training period:
ADSL Line Status
Connection Information
Line state: Connected
Connection time: 5 days, 13:38:33
Downstream: 18.56 Mbps
Upstream: 1.195 Mbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 4.8 dB / 5.7 dB
Line attenuation (Down/Up): 6.2 dB / 3.3 dB
Output power (Down/Up): 20.1 dBm / 12.3 dBm
FEC Events (Down/Up): 0 / 0
CRC Events (Down/Up): 53 / 149
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 126 / 192
Error Seconds (Local/Remote): 123 / 236
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Well, I'm now on what seems to be a 4.5db Target NM,
Eh? ??? I think not. The target SNRM would be set to one of the values in this range: 3, 6, 9, 12, 15, 18 . . . dB.
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>>> Well, I'm now on what seems to be a 4.5db Target NM,
Unlikely.. Target SNR Margin is set in 3dB increases for the plain and simple reason that it takes 3dB of 'real' SNR to load a bit into a frequency bin.
ADSL1 needs a minimum of 2 bits per subchannel - hence 6dB target SNRm.
ADSL2/2+ has better handling of Error Correction overheads and only needs to load one bit per bin and still be happy - hence min 3dB target SNRm
- Yes it should be noted that we can tweak our routers and over-ride Target SNR to specific figures but this is just making use of the fact that some bins may have a little bit more 'real SNR' and is able to load sufficient bits. The DLM set figures cant be messing with this and that and try tweaking to see what works and what doesnt.. hence it following the standards of 3,6,9,12,15 etc. Ive certainly never seen BT using 4.5dB before.
As mentioned in my post above, the only way you can find out for sure is taking some stats immediately after a reboot.
Your line has been up for >5 days, so the figure shown as Noise margin is just that... ie the current Noise Margin at that moment in time... and not the Target SNR
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This has me confused now ????. My SNR's are 5DS and 5.7US ?? I see these kind of variances day-to-day on my JDSU. What gives ??
Whoops, just seen the back end of the post ..... it's the current NM not the target. Gotcha. ;) :)
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Ah, most likely it's 3db then, and it has risen since being synced, my mistake :-[
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Ah, most likely it's 3db then, and it has risen since being synced, my mistake :-[
As mentioned in my previous posts... the only way you can tell is immediately after a resync.
Same as my post on the very top of the page ie the variance.
It can either be 3dB target SNRM and youve gained 1.5dB of SNR or
it could be 6dB target SNRM and youve lost 1.5dB of SNR
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Just a little update, my current stats:
Line state: Connected
Connection time: 3 days, 13:00:26
Downstream: 19.81 Mbps
Upstream: 1.105 Mbps
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 2.7 dB / 6.3 dB
Line attenuation (Down/Up): 6.4 dB / 3.3 dB
Output power (Down/Up): 20.1 dBm / 11.1 dBm
FEC Events (Down/Up): 0 / 0
CRC Events (Down/Up): 73 / 72
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 132 / 72
Error Seconds (Local/Remote): 68 / 62
I'm a bit worried about the noise margin, I had a PPPOA error and since I've restarted it the NM has stayed around 2.5db, I would've thought it should rise unless there's excessive noise
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Speeds are looking much better.
>>> I would've thought it should rise unless there's excessive noise.
The SNRm on a decent line will stay stable... mine often stays at 3dB for weeks on end without any variance.
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btw I know we keep nagging you, but have you tried your TG582n on that line yet?
You may well find that whilst certain routers perform well on long lines.. these often dont work so well for very short lines. In my own experience by using routers such as the TG582n and ST585 type, then I can get a much better sync speed than the routers recommended for long lines. Others on short lines also observe this too.
Your line attenuation is better than mine.. yet Im getting a higher downstream sync - regardless of the fact that Im on annex M, which should be lopping off my downstream to give to the upstream.