ADSL modem plugged into socket where there's no phone.

[HHGTTG]

Hello very useful community.

Just a quick one. Thoughts come in and out of my mind about all things teccy and was thinking that where  my BT hub is plugged into my supply, from an extension socket (not recommended, I know), does this actually require a microfilter there aa no other equipment, such as another landline phone shares that socket, only the BT Hub.

Something tells me there should be due to both voice and ADSL being there until the Voice component is turned off when changeover comes.

[WSH]

As I understand it, the filter is on the voice-side of the system although I believe it can also stop noise filtering back from a faulty phone into the broadband as well.

If you only have broadband, you don’t need the filter.  If you have DV instead of a traditional landline you don’t need it.

The though occurs though, what if the landline is still active in some form after the move to DV?  Does retaining the filter then help to keep noise out of the broadband?

[HHGTTG]

Thanks. On the two phones in the house, one corded and one DECT cordless naturally I have microfilters fitted. After the changeover to DV as you say, will there still be any extraneous noise other than than DSL which I shall still rely upon, not wishing to bother with FTTP for the near future. 

[Crimliar]

Without posting reams of info the idea is to have filtering between phone and broadband within your home telephone wiring.

Commonly on older wiring, you'll use a microfilter on every used socket - even if not strictly necessary it'll usually have no significant impact on xDSL speed.  The main exception is that if you have a "filtered faceplate" and are running a modem/router on an extension, then the extension needs to wited to the master socket plate and not the filtered faceplate (or the modem router ends up on the wrong side of the filter).

With the basics in place, you can then "suck it and see"!

[HHGTTG]

Thanks. I have the older wiring without a filtered faceplate/master socket.

[imjolly]

simple answer if your broadband drops when you make/receive a phone call you need a filter otherwise ok without

[WSH]

Just to clarify my own point.

I was running my router plugged into the DSL side of a filtered faceplate.  Since DV I have it plugged into a single socket phone only faceplate.

Performance is the same, but I do notice that the noise margin wanders all over the place more than it used to, hence the speculative question.  Personally, I’m beginning to think it is a problem on the line and just coincidence that it coincides with the switch to DV.

[Keith_Beddoe]

@WSH 

The line from the ADSL equipment in the exchange will no longer have an voltage on it. This will make it more susceptible to high resistance connections, so that is likely to be reflected, in varying performance.

Just to double check, you are on ADSL and not FTTC?

[Crimliar]

@WSH so in your specific situation:

If the extension you are connecting to is isolated, it can be wired to the xDSL side connectors of the filtered face plate and that will work fine with no additional filtering.  If it's not isolated (not just running to the single socket you have the modem/router plugged into) then it ideally needs to run from the unfiltered connections on either the faceplate or master socket and filtering at the remote socket may be needed.

That you are running over additional cable will put more noise on the line, how significant that is be dependant on the extension wiring!

[WSH]

Thanks for that @Keith_Beddoe.

That’s an interesting point and would tally with what I’ve seen.

I’m on FTTC.  I’ve just checked and what is going on now is typical of late.  Downstream is operating at 58+ Mb/s (and a throughput test has it downloading at just shy of 55).  58-59 is the “norm” for this line based on many years observations and the same as pre-DV, yet the SH2 says the max attainable is currently 53+ Mb/s with a noise margin of 4.9

It might be just a quirk of the SH2, as I’ve been using my own equipment for several years now, so I’m not familiar with the SH2.  I can’t say I really care so long as it remains stable at 58, I was just curious as to the explanation for the wandering noise margin.

As I say, your explanation tallies with observation so thanks for that.  As an after-thought, would there be any milage in reporting it as a fault?