What sets noise margin (SNR)
You're corrected Chris. I didn't mention speed, you did. The info you linked to is OK but it doesn't answer all my questions. I am trying to understand the rules of engagement - that seem to be set by BT. Given BT are an aggressive penny pinching monopoply I trust them as far as a worm can spit. Yes, that's a cynical view, but pragmatic. They want to squeeze as much value from the wires laid across the nation as they can. That's fine. I want to know if you can help counter-act the tinkering they call "IP Profile".
1) what SNR margin figure is *good* for ADSL?
6dB is the minimum value and BT increases it if they decide the line quality is too low to be usable
2) what causes SNR margin to change?
BT automates the SNR margin at the exchange. I don't know how.
2a) Why? i.e. what rules do either apply to decide it needs to change
2b) What does it change to?
BT doubles the margin which results in a logarithmic change of 3dB
3) If the SNR margin is *bad* can I manually change it?
Maybe - using your master socket, disconnect all other phones OR fit filters to them, fit an I-Plate to the master socket, disconnect the bell wire, pray to the God Furnatooo, paint yourself pink and dance naked round the BT cabinet on a full moon.
3a) if not can someone else change it?
A comms engineer might help.
4) what is a "profile"
BT decides how much bandwidth you get for your money by setting the SNR and the Power. They call this a "profile". They may or may not include other variables.
4a) who sets it,
BT
4b) can you get them to "up" it?
Not without crossing their palm with silver
My motivation
==============
I have a box from plusnet that talks to the internet. Inside that box it has values that determine the quality of reception. That quality then determines the ability to connect to the internet and the speed (my first mention of the word) it does so.
Example values from the Thomson router from Plusnet were:
output Power 17.5 dBm 11.5 dBm;
line Attenuation 57.0 dB, 31.0 dB;
snr Margin 6.5 dB, 20.0 dB
I am trying to establish if those are "good" values or not. If not, is there anything I can do to improve them, in particular for stability.
My service from Plusnet is currently experiencing router reboots which results in 100% drop-out roughly 10mins on, 2 mins off. This makes even pure surfing a painful game of snakes and ladders. Forget streaming, downloading, gaming, VOIPing. This explains my attitude to your pre-occupation with speed. I know 99% of the calls are probably from kids moaning about ping rates, iPlayer hiccups or "how dare you give me less than 4MBit/s". You have my sympathies for that.
This is a case of severe disruption of service and sheer un-usability. Unfortunately this started late November. So far I've had the following excuses:
1) it's your phone
2) it's your line (twice)
3) it's the data cap you've applied (twice)
4) it's the router over-heating
Bizarrely, it stops bouncing like Tigger on Sunny Delight during the early morning, from 3am. It lasts till about 11am, then off it goes bouncing all day. Just to add more mystery it worked fine for 2 whole days, 14 and 15th this month before deciding to revert to Tigger-mode on the 16th...
The official trouble-ticket for this is now in BT's hands since 07:00 17th Dec.
I have also managed to get to the ticket info which has the following:
Spoke to SMC Sonya to change to DCN
The next action on your Contact Us Ticket is due on Sunday 20th December at 1:00am. This ticket will remain
open with the BOT - DSL Logged Faults - No Syn until this time.
Translation please!
Sooooooooooooo, anyone like to educate me and/or get this fixed?
Mike
1) what SNR margin figure is *good* for ADSL?
6dB is the minimum value and BT increases it if they decide the line quality is too low to be usable
2) what causes SNR margin to change?
BT automates the SNR margin at the exchange. I don't know how.
2a) Why? i.e. what rules do either apply to decide it needs to change
2b) What does it change to?
BT doubles the margin which results in a logarithmic change of 3dB
3) If the SNR margin is *bad* can I manually change it?
Maybe - using your master socket, disconnect all other phones OR fit filters to them, fit an I-Plate to the master socket, disconnect the bell wire, pray to the God Furnatooo, paint yourself pink and dance naked round the BT cabinet on a full moon.
3a) if not can someone else change it?
A comms engineer might help.
4) what is a "profile"
BT decides how much bandwidth you get for your money by setting the SNR and the Power. They call this a "profile". They may or may not include other variables.
4a) who sets it,
BT
4b) can you get them to "up" it?
Not without crossing their palm with silver
My motivation
==============
I have a box from plusnet that talks to the internet. Inside that box it has values that determine the quality of reception. That quality then determines the ability to connect to the internet and the speed (my first mention of the word) it does so.
Example values from the Thomson router from Plusnet were:
output Power 17.5 dBm 11.5 dBm;
line Attenuation 57.0 dB, 31.0 dB;
snr Margin 6.5 dB, 20.0 dB
I am trying to establish if those are "good" values or not. If not, is there anything I can do to improve them, in particular for stability.
My service from Plusnet is currently experiencing router reboots which results in 100% drop-out roughly 10mins on, 2 mins off. This makes even pure surfing a painful game of snakes and ladders. Forget streaming, downloading, gaming, VOIPing. This explains my attitude to your pre-occupation with speed. I know 99% of the calls are probably from kids moaning about ping rates, iPlayer hiccups or "how dare you give me less than 4MBit/s". You have my sympathies for that.
This is a case of severe disruption of service and sheer un-usability. Unfortunately this started late November. So far I've had the following excuses:
1) it's your phone
2) it's your line (twice)
3) it's the data cap you've applied (twice)
4) it's the router over-heating
Bizarrely, it stops bouncing like Tigger on Sunny Delight during the early morning, from 3am. It lasts till about 11am, then off it goes bouncing all day. Just to add more mystery it worked fine for 2 whole days, 14 and 15th this month before deciding to revert to Tigger-mode on the 16th...
The official trouble-ticket for this is now in BT's hands since 07:00 17th Dec.
I have also managed to get to the ticket info which has the following:
Spoke to SMC Sonya to change to DCN
The next action on your Contact Us Ticket is due on Sunday 20th December at 1:00am. This ticket will remain
open with the BOT - DSL Logged Faults - No Syn until this time.
Translation please!
Sooooooooooooo, anyone like to educate me and/or get this fixed?
Mike
Thanks for the links Asbo-dog. Seems my hunch was right about BT being overly aggressive with their settings (DLM screwing up lines "because they can").
Look at the router stat pics. Any ideas why the DLM would cause this?? FYI from June to Nov my line was fine, if slow (2MBit/s). Then the trouble started and when I looked into it all, noise margin was 6dB. It stayed there for a day or 2 then upped to 9 then about 3 weeks later it jumped to 12 and then 15dB very quickly. Trouble is it's still broken. I noticed the ticket mentions 96% up-time. That's not something to be proud of. Rather like BA boasting their planes stay flying 96% of the time.
Welcome to my world.
Someone please help!
thanks
Mike
ps: how DO you tweak the SNR at your end? I have Router Stat and DLM. They both look pretty but I don't know how to use them
Look at the router stat pics. Any ideas why the DLM would cause this?? FYI from June to Nov my line was fine, if slow (2MBit/s). Then the trouble started and when I looked into it all, noise margin was 6dB. It stayed there for a day or 2 then upped to 9 then about 3 weeks later it jumped to 12 and then 15dB very quickly. Trouble is it's still broken. I noticed the ticket mentions 96% up-time. That's not something to be proud of. Rather like BA boasting their planes stay flying 96% of the time.
Welcome to my world.
Someone please help!
thanks
Mike
ps: how DO you tweak the SNR at your end? I have Router Stat and DLM. They both look pretty but I don't know how to use them
Like the Postcode 
So, no suggestions on the ticket about what to try
I guess you have noticed if the drops coincided with use of the phone.
Just to check all the bases, I'm sorry if you've been asked any of this, or tried it all, I don't have access to anything other than your posts here -
I presume you've had a listen to your phone line - can you hear/have you heard any crackling or other intermittent noise on the line? Dial a 1 to get rid of the dial tone. If you need more time before the NUT (number unobtainable tone) dial the quiet line test 17070 option 2. (Don't use any ringback or other test). Who is your Telephone Line Rental provider?
Also could you give an Outline description of your installation -
1) Have you tested in the "test" socket behind the Master front plate?
2) Whether you have any fixed extension wiring and sockets & how many, do you know roughly how the cables go from one to another;
3) What filters do you have and where is the Modem/Router plugged in?
4) Do you have a corded phone, do you have a cordless phone - if so what type - DECT or Analogue?
5) Is any other POTS (plain old telephone service) equipment (Faxes, Answer phones, Sky boxes or Alarms systems etc) plugged in/connected.
One tip: When you need to swap things around for testing, powerdown your modem/router and wait several minutes before unplugging anything that disconnects it from the line eg. it's cable, the filter, master faceplate etc. Don't do this more than 5 times in an hour, and then leave it alone for the rest of the day. This is to help prevent the exchange DLM from thinking you have a more serious intermittent problem.
Do you have access to another modem/router (and a filter you haven't tried)?
So, no suggestions on the ticket about what to try
I guess you have noticed if the drops coincided with use of the phone.
Just to check all the bases, I'm sorry if you've been asked any of this, or tried it all, I don't have access to anything other than your posts here -
I presume you've had a listen to your phone line - can you hear/have you heard any crackling or other intermittent noise on the line? Dial a 1 to get rid of the dial tone. If you need more time before the NUT (number unobtainable tone) dial the quiet line test 17070 option 2. (Don't use any ringback or other test). Who is your Telephone Line Rental provider?
Also could you give an Outline description of your installation -
1) Have you tested in the "test" socket behind the Master front plate?
2) Whether you have any fixed extension wiring and sockets & how many, do you know roughly how the cables go from one to another;
3) What filters do you have and where is the Modem/Router plugged in?
4) Do you have a corded phone, do you have a cordless phone - if so what type - DECT or Analogue?
5) Is any other POTS (plain old telephone service) equipment (Faxes, Answer phones, Sky boxes or Alarms systems etc) plugged in/connected.
One tip: When you need to swap things around for testing, powerdown your modem/router and wait several minutes before unplugging anything that disconnects it from the line eg. it's cable, the filter, master faceplate etc. Don't do this more than 5 times in an hour, and then leave it alone for the rest of the day. This is to help prevent the exchange DLM from thinking you have a more serious intermittent problem.
Do you have access to another modem/router (and a filter you haven't tried)?
Quote One last point: owing to all the above checks I think I've more than proved it cannot possibly be anything inside the house, so have refused any BT home visit on the logic that - they won't find a problem at this end AND won't turn up when it's not working either so all that will happen is I get nothing fixed and a bill for 175 quid. A nice little earner BT.
how the heck do you think they will test the line from you to the exchange then
If you have an incoming call and let it ring quite a few times, does the broadband seem to stay connected for longer after that?
Edit: When you said the 2nd Thomson gave no improvement did you mean that it gave no better speeds or was it that you were getting just as many disconnections/reboots? And when you say reboots do you mean unprompted complete reboots of the router?
Edit: When you said the 2nd Thomson gave no improvement did you mean that it gave no better speeds or was it that you were getting just as many disconnections/reboots? And when you say reboots do you mean unprompted complete reboots of the router?
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That's sounding like a hardware problem with the router. Is it overheating? It might be worth pointing a fan at it to see if keeping it cooler stops the reboots.