Understanding Noise Margin, Line Attenuation & Signal Attenuation

[tom_uk]

---

@imjolly wrote:

are you using the test socket to elimiante any problems caused by your internal wiring?

---

Thinking about it, I'm not sure what internal wiring that would be - unless you mean the internal wiring inside the socket?

On that, I bought a splitter this afternoon and tried installing it into the test socket late this evening, but without success. I got the splitter into the test socket, of course, but even after several minutes the router didn't come back up, the big 'b' just kept flashing red. I note that the splitter describes itself as an ADSL micro-filter - is that not the right item? I had read that there was no difference between ADSL and VDSL splitters/filters.

[pippincp]

Correct, the filters are the same.

[tom_uk]

---

@pippincp wrote:

Correct, the filters are the same.

---

Thanks for the confirmation. I'll try again tomorrow morning.

[imjolly]

there is no difference in the filters and connecting to test socket should give best connection not no connection at all. Are you sure that is the master socket and not and extension using a master socket. Is it the first socket where openreach line enters your home

when you connect to the test socket do any sockets still have a dial tone?

[tom_uk]

---

@imjolly wrote:

Are you sure that is the master socket and not and extension using a master socket. Is it the first socket where openreach line enters your home

---

Yep - from the pole right outside my house, to the eaves, down to the garage wall, into the garage, through the wall into the house midway along the garage, round the understairs cubby, then into the hall where the socket is. On the hall side of that route is that OpenReach socket.

[tom_uk]

Sorted now. I hadn't removed all the bits of the socket. It's a very strange multi-layer thing. The lowest level may well be very old - pre-broadband.

[imjolly]

There is something wrong as the one place your connection should work is in the test socket with a filter

[tom_uk]

Just thought I'd come back with an update on this issue.

Things seems to have improved, as a result of intervention by BT engineers. I kept calling BT helpline and kept getting not very far with them. At one point i was told I'd be sent a new Home Hub which didn't arrive so I rang again (several times) to query where it was. Turned out there was nothing in the record of the earlier call about being sent a new router! But never mind - the assistant I was talking to ran the usual tests and unusually - uniquely, in fact - found an issue with the broadband connection. As a result she raised a Fault (!) and passed it straight to engineering, and I started getting sms messages from them. That was on Tuesday, at a time when the Noise Margin was very much up and down, between just over 3 and almost 0. After a couple of further disconnects the connection has now been up for almost three days - the best duration for almost two months - and interestingly the Noise Margin is now 4. It's much more stable around that figure, as well - the variation seems to be between 3.9 and 4.3 or so, with long periods of no variation at all.

I've also noticed that the Connection Speed value has dropped a bit as well. While these problems were going on it was typically up at around 68 mbps, but since the increase of Noise Margin to 4 the Connection Speed has dropped to just under 64 mbps. I'm happy with losing a bit of speed if I've got a stable connection. (I believe there's a relationship between Noise Margin and Connection speed? - I'd be grateful if someone could point me towards something that would explain that.)

So I've closed the fault; I can re-open it, or raise another one, if the problem starts again.

[imjolly]

Try here http://www.kitz.co.uk/adsl/linestats_explanation.htm.  That is adsl but in principle similar for vdsl