I'm on ADSL2+ Unlimited

In reply to a post by RobertoS:

We need to know which BT product you are on before we can comment on the upstream speed and noise margin.

That seems like ADSL2 possibly 2+ and the upstream seems like it is capped, maybe by loads of errors, strange thing is the downstream isn't affected.

On our BT package (unlimited) our downstream is 6.0dB and upstream has always been 5.90dB.

So that seems to point to possibly getting noise 138KHz or lower, so possibly a noisy switch mode power supply.

Paul

Hunted through the log file and found this when it was all OK

00:39:55, 27 Nov. (374.630000) DSL noise margin: 5.90 dB upstream, 3.10 dB downstream
00:39:54, 27 Nov. (373.620000) DSL line rate: 1157 Kbps upstream, 18733 Kbps downstream

Do you mean the power brick for the Home Hub?

I tried a HH3 in the test socket to discount hardware and internal wiring, and got same results

So think the issue is external, but just wanted advise on my upstream dB is that was too high and what would course it externally

In reply to a post by PaulKirby:

In reply to a post by RobertoS:

We need to know which BT product you are on before we can comment on the upstream speed and noise margin.

That seems like ADSL2 possibly 2+ and the upstream seems like it is capped, maybe by loads of errors, strange thing is the downstream isn't affected.

On our BT package (unlimited) our downstream is 6.0dB and upstream has always been 5.90dB.

So that seems to point to possibly getting noise 138KHz or lower, so possibly a noisy switch mode power supply.

Paul

In reply to a post by Simon888:

Hunted through the log file and found this when it was all OK

00:39:55, 27 Nov. (374.630000) DSL noise margin: 5.90 dB upstream, 3.10 dB downstream
00:39:54, 27 Nov. (373.620000) DSL line rate: 1157 Kbps upstream, 18733 Kbps downstream

The upstream seems more like it, but the downstream is a bit low and may cause issues when you get noise on the line, which BT normally set this to 6.0dB for the downstream noise margin.

Paul

In reply to a post by Simon888:

Do you mean the power brick for the Home Hub?

I tried a HH3 in the test socket to discount hardware and internal wiring, and got same results

So think the issue is external, but just wanted advise on my upstream dB is that was too high and what would course it externally

I was referring to a switch mode power supply in general they can run at 138KHz and where the upstream goes up-to 138KHz I am assuming its a switch mode power supply issues, it could be in a TV, PC, Mains Adapter etc, and it could be internal or external to the property.

Paul

All depends on the attenuation which we don't know and WBC ADSL2+ will use 3dB margins on stable lines

My reading is that a burst of course caused (source unknown - people are guessing at a switch mode PSU with no evidence) the modem to resync and this noise was still present when resyncing hence the lower sync on the upload which used the standard 6dB target margin, then subsequently the noise went away and thus there was lots of spare noise margin again.

In reply to a post by MrSaffron:

All depends on the attenuation which we don't know and WBC ADSL2+ will use 3dB margins on stable lines

My reading is that a burst of course caused (source unknown - people are guessing at a switch mode PSU with no evidence) the modem to resync and this noise was still present when resyncing hence the lower sync on the upload which used the standard 6dB target margin, then subsequently the noise went away and thus there was lots of spare noise margin again.

yeah, I was just assuming its a switch mode power supply due to a lot of them seem to use around 138KHz as their switching frequency, but no, there is no proof this is the case.

As for the 3dB, I was told its normally 6dB and that you can ask for it to be reset if needed, I know I asked BT to reset ours to 3dB which worked fine for ages, well until we had a massive thunder storm that caused so many issues on our line I just asked for it to be set back to 6dB.

And yeah the noise could be gone, no harm in them phoning BT asking for the SNR to be reset back to 6dB.

Paul

At 10.20 this morning, ADSL disconnected.... AGAIN!

Had a look in the log file at the line stats, and WOW the dB is back down. Not to where it was, but much lower

10:20:58, 02 Dec. (79346.020000) DSL noise margin: 8.90 dB upstream, 6.00 dB downstream
10:20:57, 02 Dec. (79345.110000) DSL line rate: 1073 Kbps upstream, 17190 Kbps downstream

Did a quick speed test and YAY all seems to be back to normal.

Maybe BT have had several people moan about speed and done a bit of research and found it happened on a certain date in a certain cabinet, and someone has tinkered.

YAY

I will be monitoring carefully over the next day or so, and if all OK I will cancel the BT Engineer visit for Monday