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ac1
Aspiring Contributor
557 Views
Message 1 of 5

Low noise margin

Hi,

 

I have noticed that over the past few weeks, the downstream noise margin drops to 1.0/1.5 db from time to time, and the connection becomes intermittent. 

 

I changed my router recently from an old BT Voyager router to a Belkin N600, but I don't know if the change in router is causing the drops in noise margin as I don't recall getting the same issue with my old BT router, but I could be wrong.

 

I did the quiet line test and most of the time it was ok and sometimes there would be a crackling sound. I replaced my phone extension cable which connects the router to the phone socket and this has improved the connection speed, however the drops in noise margin still occur.

 

Therefore, I was wondering if the issue could be due to the router I am using, or something else?

 

I followed Keith Beddoe's advice from a previous post and retrained my connection by disconnecting and reconnecting several times to get the noise margin back up to 'normal' levels and the noise margin has risen from 1.0/1.5 db to 3.0/3.5 db, and was also wondering there is anything I can do to elimiinate/minimize the issue or is there nothing I can do, other than retrain my connection every so often?

 

Thanks for your help in advance.

 

Thanks

ac1

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4 REPLIES 4
DavidM
Moderator
Moderator
542 Views
Message 2 of 5

Re: Low noise margin

Hi ac1,

 

Thanks for posting. Can you try running the speed test, including further diagnostics, and post the results. We’ll take a look at this for you. I’m sure we can help.

 

Cheers

 

David

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john46
Distinguished Sage
524 Views
Message 3 of 5

Re: Low noise margin

Hi Welcome to the community forums

Here is a basic guide to getting help from the community members done by CL Keith Please read through the link posted http://forumhelp.dyndns.info/speed/first_steps.html

once you have posted the information asked for then the community members can help you more


Thank You


This is a customer to customer self help forum the only BT presence here are the forum moderators

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ac1
Aspiring Contributor
510 Views
Message 4 of 5

Re: Low noise margin

Hi guys,

 

Thanks for your posts.

 

I've kept a note of my stats over the past few days and this is as follows (As I am using a Belkin N600 router, there aren't much stats available, but I'll provide what I can):

 

With my old phone extension cable:

 

Line stats were:

 

ADSL
Type Interleave Path
Status Show Time
                   Downstream Upstream
 Data Rate (kbps)     2648 829
 Noise Margin (dB)     1.5   6.8
 Attenuation (dB)     55.9 32.1
Output power(dbm) 17.9 12.5

 

After retraining the connection, Line stats were:

 

ADSL
Type Interleave Path
Status Show Time
                        Downstream Upstream
 Data Rate (kbps)          2296   816
 Noise Margin (dB)            3.5    6.6
 Attenuation (dB)            56.9   32.1
 Output power(dbm)       17.8   12.4

 

Speed test results were:

 

1. Best Effort Test: -provides background information.
Download Speed
2.18 Mbps

0 Mbps 2 Mbps
Max Achievable Speed

Download speedachieved during the test was - 2.18 Mbps
For your connection, the acceptable range of speeds is 0.8 Mbps-2 Mbps.
IP Profile for your line is - 2.19 Mbps


2. Upstream Test: -provides background information.
Upload Speed
0.69 Mbps

0 Mbps 0.83 Mbps
Max Achievable Speed

Upload speed achieved during the test was - 0.69Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.83 Mbps

 

After changing the phone extension cable to a newer one on Friday 21/3/14:

 


Line stats on 21/3/14 were:

 

ADSL
Type Interleave Path
Status Show Time
                         Downstream Upstream
 Data Rate (kbps)           3768  902
 Noise Margin (dB)             1.5  6.4
 Attenuation (dB)            54.2 31.0
 Output power(dbm)       18.0 12.8

 

Speed test results on 21/3/14 were:

 

1. Best Effort Test: -provides background information.
Download Speed
3.61 Mbps

0 Mbps 4 Mbps
Max Achievable Speed

Download speedachieved during the test was - 3.61 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 3.32 Mbps


2. Upstream Test: -provides background information.
Upload Speed
0.77 Mbps

0 Mbps 0.83 Mbps
Max Achievable Speed

Upload speed achieved during the test was - 0.77Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.83 Mbps

After retraining the connection on 22/3/14:

 

Line stats on 22/3/14 were:

 

ADSL
Type Interleave Path
Status Show Time
                       Downstream Upstream
 Data Rate (kbps)          3448   888
 Noise Margin (dB)             3.0   5.9
 Attenuation (dB)            55.1  31.0
 Output power(dbm)       17.9 12.7

 

Speed test results on 22/3/14 were:

 

1. Best Effort Test: -provides background information.
Download Speed
3.33 Mbps

0 Mbps 4 Mbps
Max Achievable Speed

Download speedachieved during the test was - 3.33 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 3.04 Mbps


2. Upstream Test: -provides background information.
Upload Speed
0.75 Mbps

0 Mbps 0.83 Mbps
Max Achievable Speed

Upload speed achieved during the test was - 0.75Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.83 Mbps

Stats/Results as at 23/3/14 are:

 

Line stats:

ADSL
Type Interleave Path
Status Show Time
                      Downstream Upstream
 Data Rate (kbps)         3512   919
 Noise Margin (dB)         5.5      5.4
 Attenuation (dB)         54.1   31.0
 Output power(dbm)    17.9   12.7

 

Speed test results are:

 

1. Best Effort Test: -provides background information.
Download Speed
3.42 Mbps

0 Mbps 4 Mbps
Max Achievable Speed

Download speedachieved during the test was - 3.42 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 3.1 Mbps


2. Upstream Test: -provides background information.
Upload Speed
0.78 Mbps

0 Mbps 0.83 Mbps
Max Achievable Speed

Upload speed achieved during the test was - 0.78Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.83 Mbps

 

 

After I changed the phone extension cable, the downstream download speed increased however the downstream noise margin was still the same as it had been before the change 3.0/3.5 dropping to 1.0/1.5 db, although looking at the stats today, the noise margin appears to have risen.

 

I'm wondering, as I only changed the phone extension cable on Friday 21/3/14, should I wait for the 3/5 day period for the training period to pass before looking at the stats again to see if the change is helping to stabilise the noise margin?

 

Thanks in advance for your help.

 

Thanks

ac1 

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imjolly
Distinguished Sage
Distinguished Sage
505 Views
Message 5 of 5

Re: Low noise margin

I would leave the connection and post stats for the next couple of days and mods will see if they need to help you

Personally I would try and avoid phone extension cable and either use a longer rj11 modem cable or rj45 ethernet cable depending where you want the router positioned

Are you using the test socket?


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