Noise margin change

After reading the news item yesterday I notice that my noise margin changes quite alot, from the normal sort of 15-19 to as low as 1. The thing is that the connection is stable and is always solid 2MB which is what I have. I dont know if its just the Netgear router reporting it wrong.

Is there anything particular about Evenings? As the news item specifically mentioned it. Should I be worried? As if downloads and connection are fine.

I assume you're on a fixed 2mb product, yes ?

Yes fixed 2mb with Pipex.

ADSL uses the same frequencies as AM/MW radio, and interference is worse at night, because AM radio is stronger at night because the signals are bounced around by a layer in the atmosphere which is much weaker during the day.

In which case, as you're dropping as low as 1db, don't think of moving to a Max product, as you start with a target 6db noise margin, which means your line is likely to become very unstable.

It might be worth your while checking your internal wiring to see if there's a reason for such a large drop. If you have an NTE5 master socket, where the bottom part of the face plate is detachable, remove it and plug into the test socket behind. If your margin becomes more stable there, it's probably an issue with your internal wiring.

Last night I did see it drop to 0db. The internal wiring I would have thought is ok as we had BT come in and sort out the section between the PC and the main socket as my dad had screwed it up doing some DIY. I dont know if they changed the wires at all but it was all fitted by BT. Would other sections of the phone line cause this?

From resetting the router this normally brings the DB up quite abit so maybe its the router reporting incorrectly? As I think it may have even gone into minus DB last night as on the Netgear router it reports it as a massive big number.

I would have thought a true low noise margin would cause line instabalities and speed issues, but as I said mines always rock solid and perfect 2Mb speed and the router only occassionally drops connection.

It's always possible that the Netgear number is sloping off, but that tends to be gradual, not recovering during the day. The fact the number drops at night suggests it is an interference (noise) issue. Doing the test as suggested will eliminate your internal wiring, which may be the cause, especially if the ring wire is connected, terminal 3, often orange/white. Bear in mind that, if you had a 'normal' BT voice engineer do the work, it would not necessarily resolve any ADSL issues.

You need to keep the unfiltered wiring as short as possible, because it acts like an aerial for MW radio. Best case scenario is to use a filtered faceplate in the master socket, and plug the ADSL modem directly into that, which may require a long ethernet cable back to the PC(s). Ethernet wiring can be as long as you like, and doesn't have big noise issues. If you can't do that, removing the ring wire (wire #3) on the extension socket wiring at the master socket can pay dividends.

In reply to:

---

Ethernet wiring can be as long as you like, and doesn't have big noise issues.

---

I thought the limit was 100m/segment?

Yes it is, but if your house is so big that it needs more than 100m of wire between the ADSL modem and PC, I think you can afford a leased line