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Aspiring Expert
13,952 Views
Message 1 of 77

Acceptable Noise Margin

As per the title , what is an acceptable noise margin in HH5 stats ?

 

Mine was always running at around 6.3/6.0 but now suddenly it has gone to 6.3/9.8  😞

 

Accordingly my connection speed has dropped too.

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Distinguished Sage
Distinguished Sage
13,948 Views
Message 2 of 77

Re: Acceptable Noise Margin

normal is about 6db so if you have now jumped to 9.8db and dropping connection it appears there is a line noise problem and errors which have resulted in DLM increasing noise margin.  the result of higher noise margin is as you say reduced conenction speed

 

try quiet line test



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Aspiring Expert
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Message 3 of 77

Re: Acceptable Noise Margin

Quiet line test seems normally quiet tbh.

 

Connection had been very stable since last Openreach visit. The increase in noise margin has dropped my connection speed from 32 to 24.

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Sage
13,880 Views
Message 4 of 77

Re: Acceptable Noise Margin

Can you post lines 1-12 from the HH stats page?

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Aspiring Expert
13,870 Views
Message 5 of 77

Re: Acceptable Noise Margin

Looks like this may have been a temporary glitch.

 

Things seem to be returning to normal. Noise margin 6.0/6.7

 

Obviously I'll monitor this and see if things stabilise back to where they were.

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Aspiring Expert
13,818 Views
Message 6 of 77

Re: Acceptable Noise Margin

Oops , spoke too soon. Noise margin back to 8.4 and connection speed dropped again 😞

 

Can anything be done about this ?

 

Why would the noise margin begin fluctuating instead of staying around 6 ?

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Aspiring Expert
13,816 Views
Message 7 of 77

Re: Acceptable Noise Margin

1. Product name:BT Home Hub
2. Serial number:+068543+NQ51128943
3. Firmware version:Software version 4.7.5.1.83.8.204.1.11 (Type A) Last updated 08/07/15
4. Board version:BT Hub 5A
5. DSL uptime:0 days, 02:40:36
6. Data rate:4877 / 26947
7. Maximum data rate:4851 / 30493
8. Noise margin:6.4 / 8.4
9. Line attenuation:33.2 / 28.8
10. Signal attenuation:33.2 / 25.3
11. Data sent/received:4.6 MB / 23.8 MB
12. Broadband username:bthomehub@btbroadband.com
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Distinguished Sage
Distinguished Sage
13,807 Views
Message 8 of 77

Re: Acceptable Noise Margin

Your connection has reset hence the noise margin increase. Is there any noise on quiet line test as there is an underlying problem causing the resets



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Aspiring Expert
13,803 Views
Message 9 of 77

Re: Acceptable Noise Margin

Quiet line test is indeed very quiet 🙂

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Distinguished Guru
13,765 Views
Message 10 of 77

Re: Acceptable Noise Margin

There is a relationship between SNR margin (noise margin) and connection speed. The connection speed is set at sync time (reconnection time) and stays fixed for the duration of the connection up time. If you look in the Troubleshooting > Event Log > WAN section you will be able to see the sync time noise margin that was associated with your current connection speed.

From that initial starting point at sync time the noise margin can vary as the capability of the line varies due to noise fluctuations but the connection speed remains constant.

It's useful to be aware of the sync time noise margin compared to the current level. The sync time noise margin is usually set to a value around a target that the DLM sets for your line. The default sync time target is 6dB, hence you will see that mentioned as the normal level.
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