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Standard User smsmasters
(committed) Mon 07-Mar-16 23:27:47
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Noise on quiet line test (listen to recording)


[link to this post]
 
This evening I noticed my SN margin dropped to 0.2 db with an increase in CRC errors and attainable rate went down to ~20Mbps from ~40Mbps.

I did a quiet line test on 17070 and this is how my line sounds:
http://www.4shared.com/mp3/e3E74CTYba/BT_Quiet_Line_...

Previously my line was devoid of such noises.

Have already reported this as a fault.

Any ideas what could be causing this?

Seems to be related to my sync speed dropping by ~10Mbps previously: http://forums.thinkbroadband.com/fibre/t/4441199-ftt...

EDIT: Also noticed that the SN margin drops whilst the phone line is in use (which did not occur before)

Edited by smsmasters (Tue 08-Mar-16 08:37:46)

Standard User Zarjaz
(eat-sleep-adslguide) Tue 08-Mar-16 15:22:06
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Re: Noise on quiet line test (listen to recording)


[re: smsmasters] [link to this post]
 
Any ideas what could be causing this?

Yes, a poor connection between you and the cabinet somewhere.

Standard User smsmasters
(committed) Wed 09-Mar-16 12:20:00
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Re: Noise on quiet line test (listen to recording)


[re: Zarjaz] [link to this post]
 
I managed to schedule a BT engineer to come in the next few days to do some checks but concerned I may be charged £130.

Anything I should tell the engineer? Perhaps he can move me onto a better port in the FTTC cabinet?

I did some tests:
SN margin drops to nearly 0.5 db from 6db (as reported by the HG612 modem) when:
-Landline is called (without any telephones connected)
-Landine is called (with telephones connected)
-Landline is picked up

Surely this suggests a problem somewhere between the master socket and cabinet somewhere and not on my premises?


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Standard User RobertoS
(elder) Wed 09-Mar-16 13:01:46
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Re: Noise on quiet line test (listen to recording)


[re: smsmasters] [link to this post]
 
Is the noise still there if you turn off your modem/router and take it/their plugs out of the mains socket? Note - removing the power cord from the device instead is a waste of time.

The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. Sync 59504/15641kbps @ 600m. - BQM
Standard User smsmasters
(committed) Wed 09-Mar-16 13:07:35
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Re: Noise on quiet line test (listen to recording)


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
Is the noise still there if you turn off your modem/router and take it/their plugs out of the mains socket? Note - removing the power cord from the device instead is a waste of time.


Yes still there, as it sounds in the recording.

My main concern really is the FTTC side of things, even when there aren't any telephones connected to the master socket, just the RJ11 cable, if I call the landline, the SN margin still drops (as reported by the HG612 modem). Very strange.

Edited by smsmasters (Wed 09-Mar-16 13:09:34)

Standard User Zarjaz
(eat-sleep-adslguide) Wed 09-Mar-16 13:28:26
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Re: Noise on quiet line test (listen to recording)


[re: smsmasters] [link to this post]
 
Bob just asked the best question ... is the sound still present at the NTE with all else, including extension wiring, disconnected. You have answered yes to this, so that's good.

Did you report this as a noisy line fault or for the FTTC part ?

If as a noisy line, then don't be bothering the engineer with the whole SNR dipping thing .... they very likely won't be interested. Show a little interest yourself in the tests they run, ask if they don't mind you watching, if possible ask them to explain the results of the PQ (pair quality) test they run .... what you are looking for is a nice high AC balance, preferably over 60db (though the machine will pass it at 55db or over) and most importantly that both legs should be nice and balanced, ideally less than 3 nanofarad's difference between the two readings. The TDR function on their tester should be used to try and look for an HR ... also a good long listen to the quiet line test if the noise isn't immediately apparent.

If the engineers visit has been raised to look at the FTTC side of things, maybe an SFVA or a BOOST task, then feel free to mention the SNR thing, they should be able to duplicate this with their tester in manual sync mode and watching the error counter and snr whilst they use the phone at the same time.

Standard User smsmasters
(committed) Wed 09-Mar-16 13:33:37
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Re: Noise on quiet line test (listen to recording)


[re: Zarjaz] [link to this post]
 
In reply to a post by Zarjaz:
Bob just asked the best question ... is the sound still present at the NTE with all else, including extension wiring, disconnected. You have answered yes to this, so that's good.

Did you report this as a noisy line fault or for the FTTC part ?

If as a noisy line, then don't be bothering the engineer with the whole SNR dipping thing .... they very likely won't be interested. Show a little interest yourself in the tests they run, ask if they don't mind you watching, if possible ask them to explain the results of the PQ (pair quality) test they run .... what you are looking for is a nice high AC balance, preferably over 60db (though the machine will pass it at 55db or over) and most importantly that both legs should be nice and balanced, ideally less than 3 nanofarad's difference between the two readings. The TDR function on their tester should be used to try and look for an HR ... also a good long listen to the quiet line test if the noise isn't immediately apparent.

If the engineers visit has been raised to look at the FTTC side of things, maybe an SFVA or a BOOST task, then feel free to mention the SNR thing, they should be able to duplicate this with their tester in manual sync mode and watching the error counter and snr whilst they use the phone at the same time.


I reported two faults, initially for the phone line and later for broadband. It seems the BT support guy who rang me earlier scheduled the engineer visit under phone fault, from what I can see in my account. So if it's a phone fault engineer I'll just let him do his thing.

Cheers

Edited by smsmasters (Wed 09-Mar-16 13:36:55)

Standard User Zarjaz
(eat-sleep-adslguide) Wed 09-Mar-16 13:42:57
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Re: Noise on quiet line test (listen to recording)


[re: smsmasters] [link to this post]
 
So if it's a phone fault engineer I'll just let him do his thing.

No, there's a lot of new boys on the park who have had the 'charge and be damned' school of thought drummed in to them.
Show a little interest yourself in the tests they run, ask if they don't mind you watching, if possible ask them to explain the results of the PQ (pair quality) test they run .... what you are looking for is a nice high AC balance, preferably over 60db (though the machine will pass it at 55db or over) and most importantly that both legs should be nice and balanced, ideally less than 3 nanofarad's difference between the two readings. The TDR function on their tester should be used to try and look for an HR ... also a good long listen to the quiet line test if the noise isn't immediately apparent.

Follow that advice.

Good luck.

Standard User smsmasters
(committed) Wed 09-Mar-16 13:48:52
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Re: Noise on quiet line test (listen to recording)


[re: Zarjaz] [link to this post]
 
Will do.

I've been reading about high resistance faults, perhaps this could be why the SN margin drops when my landline is called (even without any telephones connected). This is the first time I've seen this behaviour occur on my line. Anything else which could cause this?

Standard User Zarjaz
(eat-sleep-adslguide) Wed 09-Mar-16 14:06:59
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Re: Noise on quiet line test (listen to recording)


[re: smsmasters] [link to this post]
 
Anything else which could cause this?

A duff filter at the customers end, and very rarely (and not applicable to you as you have FTTC) an issue with the PSTN equipment in the exchange.

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