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Standard User akawtu
(newbie) Mon 31-Dec-12 18:38:02
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Confused about my broadband speed/noise margin


[link to this post]
 
My broadband has been stuck with 15 dB noise margin for at least a couple of months. I don't mind it but I thought I should get around to resolving it.

Before this change to 15 dB it was mostly at 6 dB for a couple of years although occasionally it would drop to 3 dB but it would increase again to 6 dB due to overnight it can drop by ~2 dB.

I posted on the BT forums but I'm still clueless about it.

I did the 17070 option 2 quiet line test and I could hear a faint shhhhhhhhhhhhhhhhhhhhhhhhh sound. The test was performed with a corded telephone. An ADSL filter was plugged into the master socket, the corded phone plugged into the ADSL filter, and the broadband RJ11 cable plugged into the ADSL filter.

So I am told that the noise could be the problem because the quiet line test should be virtually silent.

I dig out a couple of the BT ADSL filters (comes with the HomeHub 3) and plug one into the master socket with only the corded phone plugged into the ADSL filter and the quiet line test is completely silent. Great, it's fixed I think!

However, I also plug the RJ11 and do the quiet line test and I am hearing shhhhhhhhhhhhhhhhhhhhhhhhhh again so after more testing including ADSL filter plugged directly into the test socket the shhhhhhhhhhhhhhhhhhhhhh sound remains when the broadband RJ11 is plugged in. There is no extension wiring.

It was suggested to try an ADSL filter plugged into another ADSL filter and doing so results in the quiet line test being completely silent even with the RJ11 cable connected.

Here is what it looks like with a Home Hub 3:

ADSL Line Status
Connection Information
Line state: Connected
Connection time: 0 days, 00:02:06
Downstream: 6.617 Mbps
Upstream: 1.101 Mbps

ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 15.2 dB / 6.1 dB
Line attenuation (Down/Up): 30.6 dB / 16.4 dB
Output power (Down/Up): 20.4 dBm / 12.2 dBm
FEC Events (Down/Up): 0 / 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 / 7
Error Seconds (Local/Remote): 0 / 0

It was at 10 to 11 Mbps when running with a 6 dB noise margin.
Standard User RobertoS
(sensei) Mon 31-Dec-12 19:16:08
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Re: Confused about my broadband speed/noise margin


[re: akawtu] [link to this post]
 
Sounds like a dodgy Home Hub or it's power supply.

Re the 15dB itself, if your double-filtering has indeed fixed the problem, that is supposed to fall by 3dB each 10-14 days of stability. Great - Not frown!

Alternatively you could try to get BT to do a reset on the line, which would set it to the 6dB default and rerun the 10-day initial period. They might want to monitor it for a few days before doing that, or they might not have a clue what you are talking about.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 54.0/14.9Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User eckiedoo
(regular) Mon 31-Dec-12 21:04:00
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Re: Confused about my broadband speed/noise margin


[re: RobertoS] [link to this post]
 
I haven't checked thoroughly; but about two months back, I read something which suggested that with the typical Phone/BB Filter, the BB side is straight through, ie NO Filtering, whilst the Phone side does have either Audio pass-through filtering or HF (BB) Rejection Filtering.

If that is the case, then theoretically, I would expect there to be virtually no reduction/attenuation to the BB signal as it passes through multiple filters in series, apart from any due to multiple luugs and sockets etc inherent in any equipment.


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Standard User RobertoS
(sensei) Mon 31-Dec-12 21:12:04
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Re: Confused about my broadband speed/noise margin


[re: eckiedoo] [link to this post]
 
You're right, but the filter is bi-directional. Not only does it remove the broadband signal from the phone side, it also prevents non-audio frequencies getting back onto the line from attached devices - i.e. it stops noise feedback from local kit.

Sky boxes sometimes need double filtering, (not as often as in the past), due to the strength of their non-audio feedback being greater than the filter can cope with. I was extrapolating from that, that perhaps there is a fault on the HH or its power unit having a similar effect.
Edit - apostropheitis cured.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 54.0/14.9Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.

Edited by RobertoS (Mon 31-Dec-12 23:00:49)

Standard User eckiedoo
(regular) Mon 31-Dec-12 22:48:41
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Re: Confused about my broadband speed/noise margin


[re: RobertoS] [link to this post]
 
Thanks for the fast reply.

To clarify, what do you mean by "Sky Boxes"?

If it is the typical Sky Satellite Box, are you referring to its phone connection for updates etc, that responds I think tothe CLI rather than the Ring Tone?

Or is it the Sky Modems/Routers etc?
Standard User Zarjaz
(knowledge is power) Mon 31-Dec-12 22:54:13
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Re: Confused about my broadband speed/noise margin


[re: eckiedoo] [link to this post]
 
Right first time, Sky Satellite Boxes.

Standard User eckiedoo
(regular) Tue 01-Jan-13 07:53:20
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Re: Confused about my broadband speed/noise margin


[re: Zarjaz] [link to this post]
 
Again my thanks.

We have an elderly Sky Satellite Box from around 2000.

Fortuitously, it is rarely connected to the phone network as we don't use the additional services; but it is occasuonally plugged in when checking for firmware updates.
Standard User akawtu
(newbie) Tue 01-Jan-13 14:37:14
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Re: Confused about my broadband speed/noise margin


[re: RobertoS] [link to this post]
 
Wow thanks for replying!

I will leave it for the 2 weeks hopefully it'll lower.

Downloading for last 10 hours+:

Data Transmitted/Received (GB): 1.7 / 4.3

Connection Information
Line state: Connected
Connection time: 0 days, 10:27:34
Downstream: 7.273 Mbps
Upstream: 1.101 Mbps

ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.5 Annex A
Latency type: Fast
Noise margin (Down/Up): 14.6 dB / 6.2 dB
Line attenuation (Down/Up): 30.4 dB / 16.4 dB
Output power (Down/Up): 20.4 dBm / 12.3 dBm
FEC Events (Down/Up): 0 / 0
CRC Events (Down/Up): 405 / 12
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): 1425 / 6
Error Seconds (Local/Remote): 148 / 9

Is this ok?
Standard User RobertoS
(sensei) Tue 01-Jan-13 16:28:35
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Re: Confused about my broadband speed/noise margin


[re: akawtu] [link to this post]
 
It looks fine. Error seconds a little higher than I like to see, but probably nothing to worry about.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 54.0/14.9Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User XRaySpeX
(eat-sleep-adslguide) Wed 02-Jan-13 00:25:42
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Re: Confused about my broadband speed/noise margin


[re: akawtu] [link to this post]
 
You should be getting 15 Meg sync speed @ 6dB NM. Even @ 15 dB NM you should be getting more than 12 Meg.

To me your ESs are fine.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC
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