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[petef]

I was looking at my father's recently installed BT ADSL2+ modem recently. When the modem is powered on the noise on the telephone makes it practically unusable. The rates reported are 270 kbps down and 980 kbps up. The exchange is ¾ mile away and Sam Knows reckons we should get about 6.5 Mbps.

What I've tried, which made no difference.

• Changing ADSL filters on phone and modem (all 3 filters behave the same)
• Changing telephones (both bad)
• Turning off wireless and disconnecting from broadband in the modem settings

I was unable to try the following.

• Replace the router
• Disconnect the extension wiring — there is no master socket, it is all hardwired

Now the telephone extension wiring is far from perfect but would that be bad enough to explain the symptoms? My best guess is the BT Home Hub 4 router but it is not a failure mode I have heard of before.

I may be able to try alternative modems and filters in a couple of weeks time. In the meantime can anyone here give opinions?

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Pete Forman
https://payg-petef.rhcloud.com/

[d2d4j]

Hi Pete

I think you will need to trace out the wiring to find the master incoming by line (usually a black wire with 1 or 2 pairs, but can be more then 2 pairs, but most unusual)

Once you have located the master line, disconnect the extensions and test

It must be old wiring if not nte(5) fitted and black sheep might be best to advice, or another user but I think BT offer a line standardisation for old or wrong wiring

I hope that helps and sorry if I'm wrong

Many thanks

John

[petef]

The socket is an old style fixed plate. The extension wiring is done internally and I did not want to interfere with that, especially as BT may take exception to tampering with the master socket if/when we call them out.

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Pete Forman
https://payg-petef.rhcloud.com/

[Dray]

I think your problems are mainly due to the extension wiring.

[ejs]

It's also possible that if Openreach visit, they will find the fault is with your extension wiring, disconnect it, not install a new master socket, and charge you for the privilege since the fault was with your extension wiring.

I'm not sure it's possible to conclude that the fault is with the extension wiring, ADSL should work reasonably well even with unfiltered extension wiring or even star wiring present, perhaps not at the optimum speed, but it shouldn't cause noise on the telephone line nor cripple the speed that much.

[Black Sheep]

I would concur with ejs, in that star-wiring (multiple extensions) will drag the speed down but wouldn't put audible noise on the line. This is usually down to two things .............. an unfiltered device plugged into a telephone socket, the usual being a set-top box such as SKY's as folk don't realise they need filtering. Or a high-resistance fault somewhere in the network between the Exchange and the socket.

Most ISP's will generally pick up the tab on an engineering visit to 'normalise' the installation. If you haven't got a proper master socket (NTE5), then you have no way of demarcating 'your' wiring from Openreach's wiring ................ so there is no way you can be charged given you haven't the opportunity to prove where the issue lies.

I would suggest you raise a Broadband fault at your earliest opportunity commenting that you do not have an NTE5, and that your master socket is an obsolete one.

[petef]

The source of the noise is definitely the router or DSLAM. I listened on the phone as it powered up and I could definitely hear it kick in. As I said before, disconnecting the WAN and disabling both WiFi frequencies did not help.

What might be the mechanism for generating audible noise? ADSL 2+ upstream starts at 25 kHz but I guesstimate that the noise I hear is at least 5 kHz. Are the sub-harmonics that strong? My best idea is that the attenuation at downstream frequencies is severe and the DSLAM is really pumping out signal on those. Or perhaps I am hearing the modem blasting upstream. Is that reasonable? The upstream rate is what you might expect but downstream is pitiful.

--
Pete Forman
https://payg-petef.rhcloud.com/

[burakkucat]

What might be the mechanism for generating audible noise? ADSL 2+ upstream starts at 25 kHz but I guesstimate that the noise I hear is at least 5 kHz.

You are probably hearing the artefacts from cross-modulation as a result of a HR and semi-conducting joint somewhere within the local loop.