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Intermittent interference on phone line

Community Veteran
Posts: 38,460
Thanks: 1,032
Fixes: 62
Registered: ‎15-06-2007

Intermittent interference on phone line

As I am in the process of switching my phone to PlusNet this isn't yet entirely PlusNet's problem but I would appreciate advice as to whether it would even be worth raising it.
Occasionally I get noise on the line which may only last for a period as short as 15 minutes but during that time a manual broadband resynch drops the upstream rate to as low as 192 kbps. Once the noise has stopped a resynch takes it back up to 448kbps with a noise margin of 20dB.
Watching my router logs I get an occasional resynch, which doesn't happen at any specific time, although it is more usual after dark, with the upstream noise margin dropping to 6dB or 7dB with low synch speeds.
It is fairly certain that something between my property and the exchange is causing interference in the lower frequency bands as the downstream speeds are relatively unaffected but given that it is very intermittent (once or twice a week is the normal frequency although I have run for two weeks without a problem).
The alternative, and perhaps easiest solution, is to get my default noise margin dropped to 12dB (it jumped from 9dB to 15dB because of a rapid series of power cuts) so that the resynchs don't drop my downstream speeds below 3,000 kbps.
10 REPLIES 10
andyb68
Newbie
Posts: 2
Registered: ‎30-07-2007

Re: Intermittent interference on phone line

I have been having the same problem for the last few days, I am running of the Whealtey, Oxfordhsire exchange. I have been dropped to 136Kb for downloads,
Community Veteran
Posts: 38,460
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Registered: ‎15-06-2007

Re: Intermittent interference on phone line

Probably against forum rules to bump my own thread but I would appreciate a response from the comms team
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: Intermittent interference on phone line

Hi Jim,
You mention your upstream speeds dropping.  Do you notice similar issues with downstream synchronisation speeds happening at the same time?
Community Veteran
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Registered: ‎15-06-2007

Re: Intermittent interference on phone line

No the downstream speeds only change by a small amount - well within tolerance
This part log is from before I changed to Vista 64 bit and the logging program wouldn't work
Quote

xDSL linestate up downstream: 3072 kbit/s, upstream: 448 kbit/s; output Power Down: 19.0 dBm, Up: 12.0 dBm;
line Attenuation Down: 50.0 dB, Up: 24.0 dB; snr Margin Down: 15.5 dB, Up: 20.0 dB)
xDSL linestate down
xDSL linestate up (downstream: 3008 kbit/s, upstream: 224 kbit/s; output Power Down: 19.0 dBm, Up: 12.0 dBm;
line Attenuation Down: 50.0 dB, Up: 24.5 dB; snr Margin Down: 15.5 dB, Up: 6.0 dB) 
Just to add these are the current stats following a manual resynch 2 days ago to get the upstream speed up from 192 kbps
Quote
Link Information
Uptime: 2 days, 0:49:49
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,648
Output Power (Up/Down) [dBm]: 12.0 / 19.0
Line Attenuation (Up/Down) [dB]: 24.0 / 50.0
SN Margin (Up/Down) [dB]: 15.0 / 9.0
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: Intermittent interference on phone line

Hmm.
I don't set how changing the target noise margin is going to help things as we don't have any way of setting a target upstream margin, which seems to be where your problem lies.
Have you done the usual filter and mdoem checks?  Something could be dying somewhere.
Community Veteran
Posts: 38,460
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Registered: ‎15-06-2007

Re: Intermittent interference on phone line

Hi James - changing the target noise margin will reduce the downstream sync rate drop if the resynch takes place when the downstream noise margin is lower.
Regarding the tests - This has been covered in two previous fault reports and tests which couldn't find anything wrong.
I think that I am answering my own question - I am going to have to live with it.
For reference these are the two previous questions ID: 21815749 ID: 23129505
pierre_pierre
Grafter
Posts: 19,757
Registered: ‎30-07-2007

Re: Intermittent interference on phone line

Nice to see some one accepting the inevitable and not carry on winging
andyb68
Newbie
Posts: 2
Registered: ‎30-07-2007

Re: Intermittent interference on phone line

Ok, BT turned up today, did some mojo up a pole and all is well with the world, even after they told me the line was fine. Just need to wait three days the get my speed back!
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: Intermittent interference on phone line

Oldjim,
Have you tried the BT automated test when you get the noise on the line. You just ring 151 and follow the instructions. Not sure if you can do the same when on Home Phone though.
Community Veteran
Posts: 38,460
Thanks: 1,032
Fixes: 62
Registered: ‎15-06-2007

Re: Intermittent interference on phone line

Yes I did - no fault found - The noise obviously wasn't severe enough