ADSL2+ with only 6dB of SNR

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kityuser

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ok people I need some help on this one.

I've been debugging adsl problems for a while but this one has me stumped, I think I've got a line problem but am struggling to convince open-reach.

I'm with BE internet adsl 2+ budget service limited to 8meg, I don't live a million miles from my exchange 1.7KM to be exact (as far as samknows is concerned) and an estimated speed of 5Meg is achievable.

I have 2 routers, the "bebox" and an older netgear adsl2+ router.
Both struggle to sync up, but do eventually at around 3Meg sync rate which stands at about 2 and a bit meg throughput (broadband speed test speeds)
When I check the router stats pages of either box (doesn;t really matter which one I use) they say I only have about 6dB of SNR up and downstream.

I'm
1) plugged straight into the master BT socket
2) no other phones or gizmos on the line
3) I AM using a filter
4) no ringer (bell) line is connected
5) no extentions or other phone connections on the line

sometimes we hear other people talking on our normal phone :-(

now when I took out the BE package I raised a ticket and open-reach changed my line to a "spare one" in the street, the bloke didn't have a clue "if my box says its ok mate then thats all I can do"...........

so I'm paying for 8meg, I'm sure I can get around 5 but only get just above 2.......


any ideas anyone.

6dB of SNR :oops:

Steve
 
I thought if the bell wire was diconnected you didn't need a filter?

I've just ordered one of these, as it happens:
 
Quite normal I would say, I think all these figures you hear banded about likely or possible speeds are just hype. Live less than 0.5km from the exchange and I get 1.7meg, my neighbour said I should switch my supplier to BT as he gets 6meg, so we ran a proper checker instead of the BT one they gave him and guess what, he was getting just under 2meg as well! :roll:

Beyond a certain point the numbers become accademic, fast enough is fast enough. Dial up was slow, 500k broadband was slow, 1meg was better, since it was upgraded to 8meg and I have been getting about 1.7 it is fast enough for what I want.
 
kasandrich":3kp8na0h said:
Quite normal I would say, I think all these figures you hear banded about likely or possible speeds are just hype. Live less than 0.5km from the exchange and I get 1.7meg, my neighbour said I should switch my supplier to BT as he gets 6meg, so we ran a proper checker instead of the BT one they gave him and guess what, he was getting just under 2meg as well! :roll:

Beyond a certain point the numbers become accademic, fast enough is fast enough. Dial up was slow, 500k broadband was slow, 1meg was better, since it was upgraded to 8meg and I have been getting about 1.7 it is fast enough for what I want.

6dB of SNR isn't "quite normal" infact its only just within the normal operating range of most of the ADSL2+ routers, and the fact that mine re-syncs quite often supports that.

I have just raised another ticket with BE, they have requested a line check, so I unplugged all my equipment, 5 mins later I get a mobile call to say that the line check has flagged and earth short problem. Open reach will attend in the morning........

the saga continues.

wizer, the filter isn't normally needed anyway, well it doesn't affect sync speed anyway, all it does is filter out folded back frequencies (that adsl use as carriers) so that you don't hear them in a phone handset.
Disconnecting the ring/bell line helps the SNR of your internal wiring as it can inject noise into the system, and hasn't been needed by modern phones for at least the last 30 years..........
filter and bell wire aren't related

Steve
 
Steve - crikey if you can hear other people talking that is pretty mad! It sounds like there is quite likely a cable fault or termination issue somewhere (moisture maybe tracking across some bad insulation or whatever).

My line is rubbish as we are far from the exchange. At the moment I'm getting:

Output Power (dBm) up/down = 12 / 16
Attenuation (dB) up/down = 31 / 60
Noise Margin (dB) up/down = 13 / 10
Reserved Bandwidth (kbit/s) up/down = 192 / 448

When ADSL2+ came in it improved my connection a lot as I was always re-syncing. Prior to that it was worse in the evenings. I figured there was more calls being made (giving crosstalk) as the noise margin went down.

Prior to that I was fortunate to have a thorough BT technician come along. He check each cable between the house/pole pole/field cab field cab/exchange. Sadly he found that the cable between the pole and field cab was causing all the problems. He changed the pair used on that cable which improved it a bit. Anyway my point with all this rambling is my dodgy connection achieves a much better SNR than yours!

I hope they manage to find the fault - a connection always dropping out is a pain.

Cheers
David
 
Hey Steve

I have a Master socket with built in backplate

I'm pretty far from the exchange and get 6.03+MB standard.

But its worth bearing in mind on all of these deals that whatever package you go for, the line to the exchange is contended (shared) with your neighbours.

I believe a standard user line is normally contended 50 - 1 (50 people sharing the line).

If you have many high users on the line, then your bandwidth may suffer.

Sounds liek your issue is physical though, but worth being aware of.

I have a BT business package which I seem to remember is contended 25 - 1. However, I do pay nigh on £50 per month for the privilage. Then again, I run my web business from home so it is business criitcal.

Hope you manage to get it solved.
 
mickthetree":v2odl5nv said:
Hey Steve

I have a Master socket with built in backplate

I'm pretty far from the exchange and get 6.03+MB standard.

But its worth bearing in mind on all of these deals that whatever package you go for, the line to the exchange is contended (shared) with your neighbours.

I believe a standard user line is normally contended 50 - 1 (50 people sharing the line).

If you have many high users on the line, then your bandwidth may suffer.

Sounds liek your issue is physical though, but worth being aware of.

I have a BT business package which I seem to remember is contended 25 - 1. However, I do pay nigh on £50 per month for the privilage. Then again, I run my web business from home so it is business criitcal.

Hope you manage to get it solved.

I think everyone has their own twisted pair to the exchange, the contention you mention is generally from the exchange to the backbone, i.e. contention for modem bandwidth at the exchange.
anyhow contention has nothing to do with a noisy line.

I seem to remember last time that the open reach guy said we had double redundancy down our road (for some reason) so he just switched me over to another twisted pair.

I know one thing, 6dB is bloody low, and just within the limits of ADSL2+ being able to sync a line at all! it would most certainly be explained by an earth fault/leak

I'm fully expecting the open reach guy to plug in his magically bpx which sends a few selcall/dtmf signalling tones (like the ones used for CLI) and claim that everything is ok. You only need a barley working line for voice to work, but ADSL and ADSL2 use the higher out-of-band (voice) frequencies the twisted pair spectrum supports, which needs alot better line quality. Lets hope the open reach guy has more than an ounce of understanding.

Steve
 
Steve

I'm knackered and need to go to bed but I will have another read of this in the morning and see what I can come up with. Also, my old fella is an Openreach engineer so I will ask him what his thoughts are.

Just so you know, I am on BE and using Bebox, am 3.7k's from the exchange (pretty much as far as you can get before it won't work at all!), SNR is 7.0down and 9.5up and I am currently getting just over 5Mb. On a good weather day I get up to 6.7Mb.

You defo have an issue, but sourcing it will be (as you know) the tricky one. Another thing to look for, is your line going through a DAX? It's a box usually fitted to either the top of the pole or between you and your neighbour and splits the signal when they are short of bellwires on a pole?

If you are then that will have a massive effect. We were on a DAX at our first house and my old fella managed to move us off it to take a line owned by a currently empty property ;) and this changed us from 300k at the time up to 2Mb.

HTH as a starting place to investigate. If you know a friendly OR engineer, or can bribe one with a few brews/£20, then it's worth getting them to check for you. My dad stuck his line tester on mine and found an issue in a box 2k away and tweaked that to get us a better line too.

It's good knowing people in the business :D
 
TrimTheKing":2ynk6d7k said:
Steve

I'm knackered and need to go to bed but I will have another read of this in the morning and see what I can come up with. Also, my old fella is an Openreach engineer so I will ask him what his thoughts are.

Just so you know, I am on BE and using Bebox, am 3.7k's from the exchange (pretty much as far as you can get before it won't work at all!), SNR is 7.0down and 9.5up and I am currently getting just over 5Mb. On a good weather day I get up to 6.7Mb.

You defo have an issue, but sourcing it will be (as you know) the tricky one. Another thing to look for, is your line going through a DAX? It's a box usually fitted to either the top of the pole or between you and your neighbour and splits the signal when they are short of bellwires on a pole?

If you are then that will have a massive effect. We were on a DAX at our first house and my old fella managed to move us off it to take a line owned by a currently empty property ;) and this changed us from 300k at the time up to 2Mb.

HTH as a starting place to investigate. If you know a friendly OR engineer, or can bribe one with a few brews/£20, then it's worth getting them to check for you. My dad stuck his line tester on mine and found an issue in a box 2k away and tweaked that to get us a better line too.

It's good knowing people in the business :D


don't think we go through a dax, no poles at all in our road (suburb), just a green junction box in the middle of the estate.

the fact we can sometimes hear other people talking but not quite quite make out what they are saying is a big hint :)
a few weeks ago Mrs KU was also having problems where she would dial a number and the line would go quiet then back to a dialling tone again :cry:

anyhow lets see what the engineer says, its cold and snowy at present, not sure he'll want to sit on a stall at the junction box in this weather , or on his hands and knees on the path.........
i'm pretty 100% sure its not a wiring problem in my house...

Steve
 
You seem to have a good understanding of line requirements but the things that stand out to me are the reluctance to sync up and the cross talk. A earth or contact fault would explain this.To listen for noise dial 17070 and option 2 phone plugged in with face plate removed. BT run large cables then distribute with smaller or overhead to the subscriber, the pair has been changed in the local cable but there can still be problems with main cables and joints insist on a new pair or good repair and quiet line.
The equipment at the exchange adjusts the line speed to give a reliable speed even when this fault is repaired it will take time to come to full speed and the router with latest updates should never be switched off.
 
IIRC bt will not come out to fix a problem which is only a dsl problem - as the line isn't spec'd for dsl as far as they're concerned it's just a voice problem.
That won't be a problem for you as you quite clearly have a voice problem.
Complain to BT that you can hear other people on the line and they 'should' come out to fix that - my bet is in fixing that you'll find that they'll also fix the dsl problem.

In my last house (new estate) they had a dsl problem which they knew about but wouldn't fix until the various building works were complete. 6dB snr isn't necessarily a great problem. I have quite happily had a stable connection with a 5.4dB snr in the past. If you've a lot of attenuation (which could be down to distance or noise) then you can have a lot of problems. Get BT to fix the voice problem and I bet your attenuation will get a lot better.
 
I think people tend to go over the top, with line noise, this that and the other.Bt have their foot on your throttle what they are giving you, who Knows?
I had a 1meg line on Aol adsl, moved to O2 adsl2 and was told in adsl forums expect no more than 2 meg even maybe still 1meg.
I am on the limit noise/distance wise 2.5km? What i ended up with was 2.8meg on day one 3.5meg on day 2 then finally 4meg on day three/current speed.
On the filter bit i once unplugged the filter and phone,then later forgot to put the filter back in and spent two hours on the phone to O2 trying to fix my 0.5meg line :oops:
 
open reach came out

" no mate, my box says everything is ok"

apparently no other noises (typical, there isn't when he was here :-( ), and the fact that sometimes Mrs KU has to dial 3 times before the far end rings is "unexplainable"


apparently we need a "broadband engineer" who can test the line at junctions in the path and the cabinet at the end of the road, I presume testing sync rates on my line at different places to find where the fault is.

bloody typical :?

Steve
 
This thread is interesting, I'm not particularly up on Broadband.

We recently had some problems with our BT phone bill and they promptly cut off our broadband until it got sorted out.

Anyway, this morning it was turned back on, we're with Sky. I took out the 20mb service but in their confirmation letter it says "Thanks for ordering our 20mb package, the best you can receive is 5.5mb"! So I take it there's no bloody point in being on their 20mb service then!

I have checked a few times during the day with speedtest.net and I'm getting a constant 3.5mb. I'm going to pay some attention to the wiring after xmas. This line is only used for broadband. It comes into the house above ground and then about 4 metres of cable to the 'master socket'.

How do I check the quality of the line?
 
kityuser My line is a similar length to yours and my problems of loss of sync were improved greatly by having 'interleaving' turned on(isp will arrange with BT ) this may slow performance in gaming but it improved my line speed and reliability.
Info from router is 5696kbps & 448kbps, attenuation 39db & 12.5db ,noise margin 6-12db &19db
Get the BT broadband engineer to check the line if its no good he will arrange for a new pair.
wizer There are tools on the net to tell you your best expected speed for the line and speed testers that keep previous results .
 
Looks like an intermittent line fault doesn't it. At least there is proof that a fault was there when the line test was done.

Given that, I'm surprised that the Openreach technician didn't change the pair to the exchange, as a matter of course. I'd be surprised if that isn't the solution.

All you can do now is let Openreach go through their procedures. Maintenance is included in your line rental, so stick with it.

Cheers

Dave
 
Deejay":9j6igmhu said:
Looks like an intermittent line fault doesn't it. At least there is proof that a fault was there when the line test was done.

Given that, I'm surprised that the Openreach technician didn't change the pair to the exchange, as a matter of course. I'd be surprised if that isn't the solution.

All you can do now is let Openreach go through their procedures. Maintenance is included in your line rental, so stick with it.

Cheers

Dave

it was cold, wintery showers, open-reach engineer really wasn't in the mood, I could tell.

looks like I got an intermittent fault, over the last 2 days I've observed worst behaviour in the evening, my guess is either as the temp drops i get a short to earth somewhere in the twisted pair, maybe condensation?
OR as the street lights turn on, I know the street lamps can really up the noise in the cabling and drop the SNR.

hopefully BE will request a broadband engineer, then I can chat to somebody who knows the difference between buttocks and elbow.....

steve
 

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